instituto de ciencia de materiales de aragÓn aragÓn

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INSTITUTO DE CIENCIA DE MATERIALES DE ARAGÓN ARAGÓN MATERIALS SCIENCE INSTITUTE

INSTITUTO DE CIENCIA DE MATERIALES DE ARAGÓN Consejo Superior de Investigaciones Científicas – Universidad de Zaragoza

Sede Campus Plaza San Francisco: Facultad de Ciencias: Pedro Cerbuna 12, 50009 Zaragoza Sede Campus Río Ebro: Edificio Torres Quevedo, María de Luna 3, 50018 Zaragoza

Teléfono: 976 76 12 31

Fax: 976 76 24 53 http://www.unizar.es/icma/

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Fondo de la portada / Background: Microfotografía de la mesofase columnar observada en un cristal líquido "tipo banana". Polarized optical microphotograph for the columnar mesophase observed for a banana-shaped liquid crystal. Imagen de la izquierda / Left figure: Cerámica de lustre de Manises, siglo XV. Cortesía del Museo de Cerámica, Barcelona. Lustre ceramic from Manises, circa XVth century. Courtesy of Museu de Ceràmica, Barcelona, Spain Imagen de la derecha / Right figure: Disposición casi lineal de átomos metálicos (en amarillo) en el primer compuesto con una cadena hexametálica de iridio. Este oligómero 1-D, con aspecto de cobre metálico, es un fragmento molecular de un "hilo metálico" relacionado con cadenas metálicas infinitas de valencia mixta, como las sales de Krogmann. (Tomado de la portada de Angew. Chem. Int. Ed.) The almost linear array of metal atoms (in yellow) in the first hexanuclear iridium-chain. This 1-D oligomer is a molecular piece of a “metal-wire” related to the infinite mixed-valence metal chains, such as the Krogmann salts. Crystalline samples of the Ir complex have a copper-like appearence. (Taken from the cover page of Angew. Chem. Int. Ed.) Editores / Editors: R. Burriel, C. Cativiela, L.A. Angurel, J. Chaboy, F. Lahoz Diseño y elaboración / Design and typing: R. Burriel, C. Cativiela, L.A. Angurel y C. Marco Impresión / Printed by: xxx Número de ejemplares / Number of copies: 1000

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ÍNDICE * ICMA: 2002-2003 * Datos estadísticos del ICMA * Selección de resultados de investigación - Ciencia y Tecnologías Químicas

- Ciencia y Tecnología de Materiales 1.- Estructura del Instituto

1.1 Organigrama 1.2 Dirección 1.3 Junta y Claustro 1.4 Departamentos de Investigación 1.5 Unidades de Apoyo

2.- Actividades

2.1 Líneas de investigación 2.1.1 Ciencia y Tecnologías Químicas 2.1.2 Ciencia y Tecnología de Materiales

2.2 Proyectos de investigación 2.2.1 Financiación europea 2.2.2 Financiación nacional 2.2.3 Financiación de las Comunidades Autónomas 2.2.4 Financiación de la industria

2.3 Divulgación científica 2.3.1 Actividades 2.3.2 Proyectos

3.- Producción científica 3.1 Artículos en revistas periódicas 3.2 Libros y obras colectivas 3.3 Tesis 3.4 Conferencias invitadas 4.- Cooperación científica 4.1 Unidades Asociadas al ICMA 4.2 Convenios con organismos extranjeros 4.3 Estancias de Investigadores en otros centros

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CONTENTS * ICMA: 2002-2003 * Statistical Data * Scientific Highlights

- Chemistry: Science and Technology - Materials Science and Technology

1.- Structure of the Institute

1.1 Organizational Chart 1.2 Administration

1.3 Institute Council and Scientific Board 1.4 Research Departments 1.5 Support Services

2.- Activities

2.1 Research Areas 2.1.1 Chemistry: Science and Technology 2.1.2 Materials Science and Technology

2.2 Research Grants 2.2.1 European Funding 2.2.2 National Funding 2.2.3 Regional Funding 2.2.4 Industrial Funding

2.3 Scientific Dissemination 2.3.1 Activities 2.3.2 Grants

3.- Scientific Productivity 3.1 Journal Articles 3.2 Books and Contributions to Compiled Works 3.3 Ph.D. Theses 3.4 Invited Lectures 4.- Scientific Cooperation 4.1 ICMA Partner Laboratories 4.2 Collaborative Agreements with Foreign Institutions 4.3 Scientific Visits to Other Institutions

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ICMA: 2002-2003

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Presentación

El Instituto de Ciencia de Materiales de Aragón (ICMA) fue creado el 24 de mayo de 1985, por un Acuerdo Específico entre el Consejo Superior de Investigaciones Científicas (CSIC) y la Universidad de Zaragoza (UZ), como Centro Mixto dependiente de las dos instituciones, acogiéndose a uno de los tipos de colaboración establecidos por el Acuerdo Marco entre el Consejo Superior de Investigaciones Científicas y la Universidad de Zaragoza.

El ICMA desarrolla sus tareas de investigación en las áreas de Ciencia y Tecnología de Materiales (MAT) y Ciencia y Tecnologías Químicas (QUI) y engloba a miembros tanto del CSIC como de la UZ, que se encuadran en Departamentos de Investigación, repartidos entre sus dos sedes: la Facultad de Ciencias, sita en el campus Plaza San Francisco, y el Centro Politécnico Superior, ubicado en el campus Río Ebro, ambos en Zaragoza.

Se presenta en esta memoria la actividad del Instituto durante los años 2002 y 2003 en forma bilingüe, castellano e inglés, para facilitar su diseminación entre colegas de la comunidad científica internacional.

Se ha puesto especial énfasis en describir las líneas de investigación en las que trabajan los distintos grupos y se han seleccionado algunos resultados desarrollados en estas líneas durante los dos años.

Los gráficos estadísticos ofrecidos al principio muestran la composición del personal del Instituto y su distribución entre las dos instituciones y las dos áreas científicas a las que pertenecen. Muestran también la evolución de algunos parámetros importantes durante los últimos diez años como son, personal, ingresos externos, tesis y publicaciones. En los últimos años se ha estabilizado el número de miembros permanentes de la UZ y se ha producido un aumento sostenido en el número de los del CSIC. Ha habido una disminución drástica en el número de tesis doctorales fruto del proceso sufrido por el alumnado de los centros universitarios relacionados con el Instituto. La financiación ha crecido notablemente en los últimos años y la producción científica se mantiene en niveles cuantitativos constantes.

Durante estos dos años ha habido las siguientes incorporaciones de personal permanente: Antonio Martín Tello, Ana Carmen Omenat Val y Fernando Luis Vitalla como Científicos Titulares y Concepción Marco Pérez como Auxiliar Administrativa en comisión de servicios. Se ha producido la baja por jubilación de Domingo González Álvarez que fue miembro fundador y director del Instituto durante cuatro años y la de Berta García Landa por excedencia voluntaria. Los siguientes miembros permanentes han tenido una promoción en su posición: Daniel Carmona Gascón, Conrado Rillo Millán, Pedro Algarabel Lafuente y Miguel Angel Ciriano López a Profesores de

Investigación, José Ignacio García Laureiro y Mª Cristina Tejel Altarriba a Investigadores Científicos y Agustín Camón Lasheras a Científico Titular.

El programa nacional de contratación de investigadores postdoctorales Ramón y Cajal ha posibilitado la incorporación de 12 doctores en las dos convocatorias resueltas hasta finales del 2003.

Se ha iniciado la remodelación del edificio A de la Facultad de Ciencias de la UZ que afecta a una gran parte de los Departamentos del área de Materiales.

En cuanto a dotación de infraestructura científica común al Instituto se ha ampliado el servicio de Resonancia Magnética Nuclear con dos espectrómetros AVANCE 400 y se ha obtenido la financiación para una plataforma de medidas físicas PPMS de Quantum Design destinada al servicio de medidas magnéticas.

Ha habido un aumento notable en cuanto a la participación de la Diputación General de Aragón en la dotación de fondos de investigación y ha promovido la estructuración de grupos consolidados, grupos emergentes y grupos de investigación aplicada, proporcionando una financiación básica de funcionamiento.

El período que abarca esta memoria queda enmarcado por la aprobación de las normas reguladoras de los dos organismos patronos del Instituto, el estatuto del CSIC a finales del 2000 y los estatutos de la UZ justo al terminar 2003. A su vez ha empezado un proceso de generación de Institutos propios universitarios en el que miembros del ICMA han tenido una participación importante. Todo esto está exigiendo replantear los modos de colaboración entre Institutos y establecer la necesidad de una adecuación del plan de actuación científica del ICMA y de sus normas de funcionamiento. El Instituto también ha participado en el plan estratégico de la Universidad de Zaragoza con la elaboración del suyo propio.

En mitad del período reseñado en la Memoria se ha producido el relevo de la dirección del Instituto y desde aquí se agradece la constante colaboración del equipo saliente y la disponibilidad del personal del Instituto en las tareas comunes demandadas por las actividades institucionales.

Ramón Burriel, Director del ICMA

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Introduction

The Aragón Materials Science Institute was launched as a Joint Research Center on May 24, 1985, by formal agreement between the Spanish Council for Scientific Research (CSIC) and the University of Zaragoza (UZ). The Institute draws resources from, and responds to, both institu-tions under terms established in the 'CSIC-UZ Framework Agreement' upon which the Institute was founded.

The Institute conducts research in the divisions of Materials Science and Technology (MAT) and Chemistry: Science and Technology (QUI) and includes both CSIC and UZ personnel, organized into research Departments located at two sites -- the Faculty of Sciences at the University's Plaza San Francisco campus and the School of Engineering at the Río Ebro campus, both in Zaragoza.

This biennial report presents the activities of the Institute in 2002 and 2003, in both Spanish and English, so as to facilitate wider dissemination among colleagues in the inter-national scientific community.

Special emphasis has been given to descriptions of the specific research projects pursued by the different groups belonging to the Institute through 2002-2003, and selected results are presented.

The graphics presented at the beginning of the report detail the distribution of Institute personnel between its two parent institutions and between its two divisions -- Chemistry and Materials. They also show the evolution of some important parameters over the last ten years, such as the number of scientists, external funding, number of Ph.D. theses presented and publications. The last few years have seen a levellng off of the number of permanent UZ personnel in the Institute and a steady increase in the number of CSIC scientists; there has been, in addition, a drastic decrease in the number of Ph.D. theses, reflecting a similar trend in the undergraduate student body as it relates to departments associated with the Institute. Funding has increased considerably in the past few years, and scientific productivity has been maintained at a constant quantitative level.

In the two years covered by this report, new permanent personnel entered the Institute -- Antonio Martín Tello, Ana Carmen Omenat Val and Fernando Luis Vitalla as Tenured Scientists and Concepción Marco Pérez as Administrative Assistant on secondment. Founding member and former Director of the Institute, Domingo González Álvarez, retired and Berta García

Landa took voluntary leave of absence. The following Institute members were promoted -- Daniel Carmona Gascón, Conrado Rillo Millán, Pedro Algarabel Lafuente and Miguel Angel Ciriano López to Research Professors, José Ignacio García Laureiro and Mª Cristina Tejel Altarriba to Research Scientists, and Agustín Camón Lasheras to Tenured Scientist.

The national 'Ramón y Cajal' program for hiring postdoctoral fellows made possible the incorporation of 12 new doctoral level scientists by the end of 2003.

Remodeling began on Building A of the Faculty of Sciences, affecting most of the Departments in the Materials division.

Funding for capital equipment for the common support services of the Institute led to expansion the Nuclear Magnetic Resonance service with two ADVANCE 400 spectrometers. In addition, funding has been obtained for a Quantum Design PPMS physical measurements platform for the Magnetic Measurements service.

There has been a substantial increase in research support from the regional government of Aragón, which formally recognized consolidated research groups, emerging groups and applied research groups, providing basic working funding.

The period of this report is bounded by the approval of regulations governing both of the Institute's parent organizations -- the statute of the CSIC at the end of 2000 and the statutes of the UZ at the end of 2003. Moreover, the establishment of University Institutes was initiated during this period, with significant participation by members of ICMA. All of this necessitated a reconsideration of the collaborative relationships among Institutes and a renovation of the scientific program and operating procedures of ICMA. The Institute also contributed its own strategic framework plan to that developed at the same time by the University of Zaragoza.

The Institute underwent a change of administration in the middle of the period covered by this report. We thank the previous administrative team for their ongoing collaboration, and we are grateful to all of the Institute personnel who contribute voluntarily to the realization of the common tasks demanded by institutional activities.

Ramón Burriel, Director of ICMA

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Datos Estadísticos del ICMA ICMA Statistical Data

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PERSONAL PERSONNEL Distribución de personal a 31 de diciembre de 2003 Personnel distribution as of December 31, 2003

Personal Funcionario Permanent Staff

125

Consejo Superior de Investigaciones Científicas Spanish Council for Scientific Research

53

Profesores de Investigación

Research Professors 11

Investigadores Científicos Research Scientists

8

Científicos Titulares 22 Tenured Scientists Personal Administrativo

Administrative Personnel 4

Personal Técnico Technical Personnel

8

Universidad de Zaragoza University of Zaragoza

72

Catedráticos de Universidad

Full Professors 14

Titulares de Universidad Assistant Professors

46

Catedráticos de Escuela Universitaria Professors of College

1

Titulares de Escuela Universitaria College Assistant Professors

11

Personal contratado y becarios Contract Personnel and Students

126

Contratados postdoctorales Postdoctoral Researchers

17

Profesores contratados Non-Tenured Faculty

15

Becarios Ph.D. Students

76

Investigadores contratados Research Fellows

6

Técnicos contratados Technical Engineers

12

11

CSIC

UZ

4172

Materiales

Química

6251

Personal científico permanente

Scientific Staff

Materiales

Química

2516

Materiales

Química

3735

Personal permanente CSIC Personal permanente UZ CSIC Scientific Staff UZ Scientific Staff

Materiales

Química

3541

Materiales

Química

107

Becarios Contratados postdoctorales RyC e I3P

Ph.D. Students Postdoctoral Contracts RyC and I3P

12

0

10

20

30

40

50

60

70

80

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

CSIC

UZ

Evolución del número de científicos permanentes

Evolution of the Number of Staff Scientists

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FINANCIACIÓN FUNDING

Financiación del ICMA, indicando el organismo por la que se ha gestionado

Funding of ICMA, according to administrating entity

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

MaterialesQuímicaTotal

Año

Mill

ones

de

euro

s

Recursos externos generados en las dos áreas del ICMA

External funding generated by the two divisions of the Institute

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Financiación del ICMA (en euros) clasificada por origen y organismo gestor

Funding of ICMA (Euros) clasified by source and managing entity

AÑO 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Gestionado por CSIC Presupuesto ordinario 32.571 34.616 34.616 34.490 40.719 63.341 66.397 62.393 76.442 78.813Nacional 468.008 637.602 550.383 326.085 246.968 708.260 457.260 551.271 695.498 759.994UE 99.552 130.257 111.193 35.418 50.359 30.184 34.608 109.009 148.817 60.436Contratos y convenios 10.746 15.626 26.320 39.191 21.695 90.000 22.353Otros 33.002 16.233 10.476 9.039 19.335 32.874 22.327 166.250 47.948 129.811Dotaciones extraordinarias 106.980 48.195 22.694 42.005 26.259 273.479 448.307 217.446 433.926

Total CSIC 750.859 866.903 706.668 393.237 415.012 887.238 893.262 1.358.925 1.276.151 1.485.333

Gestionado por Universidad de Zaragoza Nacional 368.090 371.546 461.397 594.317 640.396 396.668 678.131 682.823 910.962 1.463.585UE 124.217 31.715 221.052 180.304 281.694 140.086 246.112 157.597 321.566 461.386Contratos y convenios 248.134 297.297 393.453 409.187 20.951 41.630 62.211 81.437 28.896 362.137Otros 33.002 19.178 10.476 14.869 26.817 59.760 105.359 215.864 7.754 32.894Dotaciones extraordinarias 7.813 3.606

Total UZ 773.443 719.736 1.086.378 1.198.677 977.671 641.750 1.091.813 1.137.721 1.269.178 2.320.002

Total ICMA Presupuesto ordinario 32.571 34.616 34.616 34.490 40.719 63.341 66.397 62.393 76.442 78.813Nacional 836.098 1.009.148 1.011.780 920.402 887.364 1.104.928 1.135.391 1.234.094 1.606.460 2.223.579UE 223.769 161.972 332.245 215.722 332.053 170.270 280.720 266.606 470.383 521.822Contratos y convenios 258.880 297.297 393.453 409.187 36.577 67.950 101.402 103.132 118.896 384.490Otros 66.004 35.411 20.952 23.908 46.152 92.634 127.686 382.114 55.702 162.705Dotaciones extraordinarias 106.980 48.195 22.694 49.818 29.865 273.479 448.307 217.446 888.945

TOTAL 1.524.302 1.586.639 1.793.046 1.626.403 1.392.683 1.528.988 1.985.075 2.496.646 2.545.329 3.805.335

% gestionado por CSIC 42,3 54,6 39,4 26,3 29,8 58,0 45,0 54,4 50,1 39,0 % gestionado por UZ 57,7 45,4 60,6 73,7 70,2 42,0 55,0 45,6 49,9 61,0

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Recursos externos correspondientes al área de Ciencia y Tecnologías Químicas (en euros) clasificados por origen y organismo gestor

External funding (Euros) generated by the Chemistry: Science and Technology division, clasified by source and managing entity

AÑO 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Gestionado por CSIC

Nacional 207.830 342.174 236.859 173.212 99.828 89.358 154.093 176.252 197.718 201.085UE 56.808 115.677 107.888 35.418 4.958 Contratos y convenios 8.655 1.154 1.785Otros 12.201 6.076 4.670 1.743 3.312 4.837 6.929 17.079 40.715

TOTAL 276.838 463.927 349.416 210.372 108.098 94.195 154.093 191.836 215.951 243.585

Gestionado por Univ. Zaragoza Nacional 131.622 236.198 217.687 290.589 280.072 166.480 223.577 292.392 480.434 659.630UE 31.421 17.111 19.773 96.000 60.000 60.000Contratos y convenios 6.010 12.573 25.363 24.040 79.311 6.000 8.300Otros 2.945 5.830 7.483 26.887 83.033 49.614 16.500

TOTAL 169.053 256.254 237.460 296.419 300.127 218.730 426.650 421.317 546.434 744.430

TOTAL ÁREA DE CIENCIA Y TECNOLOGÍAS QUÍMICAS Nacional 339.452 578.372 454.545 463.801 379.900 255.839 377.670 468.645 678.152 860.715UE 88.229 132.788 127.661 35.418 4.958 96.000 60.000 60.000Contratos y convenios 6.010 12.573 25.363 24.040 87.965 7.154 10.085Otros 12.201 9.021 4.670 7.573 10.794 31.724 83.033 56.543 17.079 57.215

TOTAL 445.891 720.181 586.876 506.791 408.225 312.925 580.743 613.153 762.385 988.015

% gestionado por CSIC 62,1 64,4 59,5 41,5 26,5 30,1 26,5 31,3 28,3 24,7 % gestionado por UZ 37,9 35,6 40,5 58,5 73,5 69,9 73,5 68,7 71,7 75,3

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Recursos externos correspondientes al área de Ciencia y Tecnología de Materiales (en euros) clasificados por origen y organismo gestor

Project funding (Euros) generated by the Materials Science and Technology division clasified by source and managing entity

AÑO 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Gestionado por CSIC

Nacional 260.178 295.427 313.524 152.873 147.140 618.902 303.167 375.018 497.780 558.909UE 42.744 14.581 3.306 45.400 30.184 34.608 109.009 148.817 60.436Contratos y convenios 10.746 15.626 26.320 39.191 13.040 88.846 20.568Otros 20.801 10.157 5.806 7.296 16.023 28.037 22.327 159.321 30.869 89.096

TOTAL 334.469 320.165 322.635 160.170 224.190 703.443 399.293 656.390 766.312 729.009

Gestionado por Univ. Zaragoza Nacional 236.468 135.348 243.710 303.727 360.325 230.188 454.554 390.431 430.528 803.955UE 92.796 14.605 201.279 180.304 281.694 140.086 150.112 157.597 261.566 401.386Contratos y convenios 242.124 297.297 393.453 409.187 8.378 16.267 38.171 2.126 22.896 353.837Otros 33.002 16.233 10.476 9.039 19.335 32.874 22.327 166.250 7.754 16.394

TOTAL 604.390 463.483 848.918 902.257 669.732 419.415 665.164 716.405 722.744 1.575.572

TOTAL ÁREA DE CIENCIA Y TECNOLOGÍA DE MATERIALES Nacional 496.646 430.775 557.234 456.601 507.465 849.090 757.722 765.449 928.308 1.362.864UE 135.540 29.185 204.585 180.304 327.095 170.270 184.719 266.606 410.383 461.822Contratos y convenios 252.870 297.297 393.453 409.187 24.004 42.587 77.362 15.167 111.742 374.405Otros 53.803 26.390 16.281 16.336 35.358 60.910 44.654 325.572 38.623 105.490

TOTAL 938.859 783.648 1.171.553 1.062.427 893.921 1.122.858 1.064.457 1.372.794 1.489.056 2.304.581

% gestionado por CSIC 35,6 41,1 27,6 14,0 24,1 62,1 36,6 51,7 51,5 31,6 % gestionado por UZ 64,4 58,9 72,4 86,0 75,9 37,9 63,4 48,3 48,.5 68,4

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PRODUCCIÓN CIENTÍFICA SCIENTIFIC PRODUCTIVITY

2002

Artículos publicados en revistas científicas ordenadas por su factor de impacto Number of scientifc papers published in each journal arranged by impact factor (SCI)

F. Impacto

Impact factor

Artículos Articles

Revista Journal

F. Impacto

Impact factor

Artículos Articles

Revista Journal

26,682

1

Science

1,435

1

J. Non-Cryst. Solids

7,671 1 Angew. Chem. Int. Ed. 1,414 1 Polyhedron 7,323 3 Phys. Rev. Lett. 1,359 1 Inorg. Chem. Commun 6,201 3 J. Am. Chem. Soc. 1,335 1 Eur. J. Mineral. 4,614 5 Chem. Eur. J. 1,306 1 Phys. Chem. Miner. 4,207 4 Appl. Phys. Lett. 1,260 1 Can. J. Chem. 4,038 6 Chem. Commun. 1,219 1 Metall. Mater. Trans. A 3,967 1 Chem. Mater. 1,142 2 J. Eur. Ceram. Soc. 3,751 1 Macromolecules 1,140 1 J. Phys. Chem. Solids 3,715 1 Org. Lett. 1,046 14 J. Magn. Magn. Mater. 3,611 3 J. Phys. Chem. B 1,016 2 IEEE T. Magn. 3,327 20 Phys. Rev. B 1,014 1 J. Alloy Comp. 3,217 2 J. Org. Chem. 0,950 1 Comput. Mech. 3,215 20 Organometallics 0,940 2 Surf. Rev. Lett. 3,104 1 Acta Mater. 0,912 3 Physica C 3,023 6 J. Chem. Soc. Dalton 0,892 1 Mater. Lett. 2,991 1 Adv. Synth. Catal. 0,885 1 J. Synchrotron Radiat. 2,950 6 Inorg. Chem. 0,808 1 Int. Appl. Mech. 2,765 2 J. Phys. Chem. A 0,764 1 Cement Concret. Res. 2,683 5 J. Mater. Chem. 0,697 2 Phase Transit. 2,526 6 Eur. J. Inorg. Chem. 0,658 1 Desalination 2,420 5 Tetrahedron 0,613 1 Mater. Sci. Forum 2,360 3 Europhys. Lett. 0,609 5 Physica B 2,357 4 Tetrahedron Lett. 0,604 3 Int. J. Mod. Phys. B 2,281 6 J. Appl. Phys. 0,537 1 Bio-Med. Mater. Eng. 2,231 4 Appl. Phys. A: Mater 0,459 1 J. Eng. Mat-T. Asme 2,203 1 Chem. Phys. 0,414 1 High Pressure Res. 2,195 1 Eur. J. Org. Chem. 0,408 4 Ferroelectrics 2,163 3 Tetrahedron: Asymmetry 0,345 1 Acta Phys. Pol. A 2,138 3 Supercond. Sci. Technol. 0,155 2 Afinidad 2,060 1 New J. Chem. - 2 Abstr. Papers Am. Chem. 2,051 1 Bioorg. Chem. Med. Lett. - 1 Acros. Org. Act. 1,965 1 J. Membrane Sci. - 2 Acta Crystallogr. E 1,915 1 Appl. Catal. A: Gen. - 1 An. Quim. 1,901 5 J. Organomet. Chem. - 1 Appl. Mech. Rev. 1,838 1 Phys. Chem. Chem. Phys. - 1 Ceramic Engineering 1,796 2 J. Am. Ceram. Soc. - 5 CIT 1,775 5 J. Phys. Condens. Mat. - 1 Cryst. Eng. Comm. 1,741 1 Eur. Phys. J. B - 2 Inorg. Synth. 1,691 1 J. Pept. Sci. - 1 Investigación y Ciencia 1,671 2 J. Solid. Stat. Chem. - 1 Prop. Solid Mech. 1,667 1 Solid State Sci. - 1 Rev. TdD 1,597 3 Liq. Cryst. 1,575 1 Chirality 236 1,566 1 Inorg. Chim. Acta 1,529 1 J. Cryst. Growth 1,443

2 Thin Solid Films

18

2003

Artículos publicados en revistas científicas ordenadas por su factor de impacto Number of scientifc papers published in each journal arranged by impact factor (SCI)

F. Impacto

Impact factor

Artículos Papers

Revista Journal

F. Impacto

Impact factor

Artículos Papers

Revista

Journal

8,427

3

Angew. Chem. Int. Ed.

1,693

3

J. Photoch. Photobio.

7,305 2 Adv. Mater. 1,584 6 Polyhedron 7,035 8 Phys. Rev. Lett. 1,581 1 Catal. Lett. 6,516 8 J. Am. Chem. Soc. 1,578 11 Inorg. Chim. Acta 5,951 1 Coord. Chem. Rev. 1,285 1 Metall. Mater. Trans. A 4,614 7 Chem. Eur. J. 1,223 3 IEEE T. Appl. Supercon. 4,374 3 Chem. Mater. 1,192 3 Physica C 4,092 4 Org. Lett. 1,171 1 J. Low Temp. Phys. 4,049 3 Appl. Phys. Lett. 1,158 3 Liq. Cryst. 4,031 1 Chem. Commun. 1,144 1 J. Synchrotron Radiat. 3,783 1 Adv. Synth. Catal. 1,080 2 J. Alloy Comp. 3,679 1 J. Phys. Chem. B 1,070 1 Mat. Sci. Eng. B-Solid. 3,643 1 Acta Crystallogr. B 1,041 1 Nucl. Instrum. Meth. B 3,621 1 Macromolecules 1,026 1 J. Phys. Chem. Solids 3.539 1 Trac-Trend Anal. Chem. 0,983 1 Metrología 3,389 7 Inorg. Chem. 0,958 1 Prog. Org. Coat. 3,375 17 Organometallics 0,956 1 Thermochim. Acta 3,297 2 J. Org. Chem. 0,930 1 Physica E 3,276 1 J. Catal. 0,910 3 J. Magn. Magn. Mater. 3,023 7 J. Chem. Soc. Dalton 0,908 2 Physica B 2,962 15 Phys. Rev. B 0,853 1 Synth. Commun. 2,950 1 J. Chem. Phys. 0,840 1 Transit. Metal. Chem. 2,825 1 Appl. Catal. A: Gen. 0,746 1 Phys. Solid. State 2,820 1 Green Chem. 0,703 2 IEEE T. Instrum. Meas. 2,789 2 Rapid.Commum. Mass Spectron. 0,641 1 Cement Concret. Res. 2,741 1 Synlett 0,518 2 Cr. Chim. 2,733 1 Biopolymers 0,492 1 Indian J. Chem. A 2,641 2 Tetrahedron 0,472 1 Syn. React. Inorg. Mat. 2,640 1 Curr. Op. Sold. Stat. Mat. Sci. 0,440 1 Hyperfine Interact. 2,482 4 Eur. J. Inorg. Chem. 0,319 2 J. Phys. IV 2,340 1 Polymer 0,246 1 Bol. Soc. Esp. Ceram. V 2,326 3 Tetrahedron Lett. 0,208 5 Acta Crystallogr. C 2,304 1 Nanotechnology - 1 Anal. Bional. Chem. 2,264 1 J. Mol. Catal. A.Chem. - 1 Anal. Quim. 2,227 2 Eur. J. Org. Chem. - 1 Adv. Sci. Tech. 2,202 2 Phys. Rev. E - 1 Ceramic Engineering 2,182 1 Bioorg. Chem. Med. Lett. - 2 Comput. Plast. 2,178 9 Tetrahedron: Asymmetry - 1 Corrosión y Protección 2,171 8 J. Appl. Phys. - 1 Ingeniería Naval 2,075 1 Europhys. Lett. - 6 Materiales Compuestos 2,074 1 Synthesis - 1 Org. Biomol. Chem. 2,042 3 J. Organomet. Chem. - 1 Photonics and Nanoestructures 1,885 3 Gold Bull. - 1 Phys. Chem. News 1,849 1 Nucleos. Nucleot. Nucl. - 1 Recent. Res. Devel. Mat. Sci. 1,799 2 Chaos - 1 Rev. Esp. Física 1,757 2 J. Phys. Condens. Mat. - 1 Wind Energy 1,693

1 Photoch. Photobio. Sci.

236

19

Evolución del número de publicaciones entre los años 1994 y 2003 Evolution of the number of articles from 1994 to 2003

0

5

10

15

20

25

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

Evolución del número de tesis doctorales presentadas entre los años 1994 y 2003

Evolution of the number of Ph.D. Theses from 1994 to 2003

21

Selección de Resultados de Investigación

Scientific Highlights

22

Izquierda: Micrografía con microscopía electrónica de barrido de una sección transversal de una barra del eutéctico Al2O3-YAG obtenida por fusión zonal inducida con láser a 350 mm/h. La fase clara es YAG y la fase oscura α-Al2O3. Left: SEM micrograph of a transverse section of Al2O3-YAG eutectic grown at 350 mm/h using a Laser Floating Zone technique. The bright phase is YAG and the dark phase α-Al2O3. Derecha: Disco que contiene una suspensión del compuesto [(C6F5)2Au{µ-Ag(OClO3)}Au(C6F5)2] bajo luz ultravioleta. El borde del disco está enfriado con nitrógeno líquido a una temperatura cercana a 77 K y el centro se encuentra a temperatura ambiente Right: A disc containing a suspension of the complex [(C6F5)2Au{µ-Ag(OClO3)}Au(C6F5)2] (solid) under ultraviolet light. The border of the disc is cooled with liquid nitrogen to a temperature close to 77 K and the centre of the disc is at room temperature.

23

Ciencia y Tecnologías Químicas Chemistry: Science and Technology

24

− Transition – metal allenylidene complexes can become tools for organic synthesis more important than the carbene compounds of type LnM=CR2. M. L. Buil, M. A. Esteruelas, A. M. López, E. Oñate.

− A bicyclic analogue of proline stabilises the βl-turn peptide conformation.

A. M. Gil, E. Buñuel, A. I. Jiménez, C. Cativiela.

− Nucleoside analogues: future of chemotherapeutic agents. P. Merino, T. Tejero, F. L. Merchán, S. Franco, P. Romero, J. A. Matés, V. Mannucci.

− “Greening” the chemistry through catalysis.

J. M. Fraile, J. I. García, J. A. Mayoral.

− C-H activation/functionalization sequences in diiridium complexes. E. Sola, M. V. Jiménez, Y. Yuan, F. J. Lahoz, L. A. Oro.

− Discrete mixed-valence iridium chains.

C. Tejel, M. A. Ciriano, B. E. Villarroya, J. A. López, F. J. Lahoz, L. A. Oro.

− Vapochromic complexes. E. J. Fernández, J. M. López de Luzuriaga, M. Monge, M. E. Olmos, J. Pérez, A. Laguna.

25

TRANSITION – METAL ALLENYLIDENE COMPLEXES CAN BECOME TOOLS FOR

ORGANIC SYNTHESIS MORE IMPORTANT THAN THE CARBENE COMPOUNDS OF TYPE LnM=CR2

M. L. Buil, M. Á. Esteruelas, A. M. López, E. Oñate

The hydroamination of alkynes in the

presence of transition metal complexes is an attractive route to prepare numerous classes of organonitrogen molecules1. Two basic approaches have been employed to effect aminations and involve either alkyne or amine activation routes. Alkyne activation is generally accomplished with late transition-metals, which render π-alkyne intermediates. The coordination of the alkyne to the metallic center enhances its electrophilic character, making the alkyne susceptible of undergoing the direct nucleophilic addition of the amine 2.

The evidence that vinylidene-metal intermediates, LnM=C=CHR, are easily formed from terminal alkynes and transition metals, brings along an alternative alkyne activation route. The reactivity of the vinylidene-metal moiety is dominated by the electrophilicity and nucleophilicity of the Cα and Cβ atoms, respectively 3. As a result, one of the N-H bonds of primary amines adds across the highly polarized Cα-Cβ double bond of the vinylidene to afford "aminocarbene derivatives" 4.

Allenylidene compounds LnM=C=C=CR2, which belong to the series of unsaturated carbene derivatives LnM=C(=C)mCR2 (m>0), has been much less studied than the vinylidene complexes. EHT-MO calculations indicate that the carbon atoms of the unsaturated chain of the allenylidene are alternatively electron-poor and electron-rich, starting from the metal center 5. Hence, electrophilic centers are located at the Cα and the Cγ atoms, while the Cβ atom is a nucleophilic site.

The coordination of the π-acidic carbonyl group to the metallic fragment containing the allenylidene ligand enhances the reactivity associated with the allenylidene spine. Thus, we have recently shown that the allenylidene ligand of the complex [Ru(η5-C5H5)(=C=C=CPh2)(CO)-(PiPr3)]BF4 (1) reacts with propargylamines and diallylamine to afford heterocyclic compounds, which are the result of the addition of the nitrogen atom of the amine to the Cα atom of the allenylidene and one or two C-C couplings.

Similarly to the vinylidene complexes, the Cα-Cβ double bond of the allenylidene ligand of 1 undergoes the addition of one of the N-H bonds of propargylamine, to give the secondary azoniabutadienyl derivative 2 (eq. 1). Treatment of the latter with KOH in methanol produces its deprotonation and the formation of the bicycle complex 3 as a result of a double C-C coupling, the Cα and Cγ atoms of the allenylidene of 1 and the Cβ atom of the allenylidene with the Cβ atom of the propargylamine.

The formation of the bicycle from the unsaturated η1-carbon donor ligand of 2 is a three-elemental-step reaction involving: (i) deprotonation of the nitrogen atom, (ii) propargyl to allene isomerization catalyzed by the solvent (methanol), and (iii) double intramolecular C-C coupling. The three membered ring is a result of a novel intramolecular cyclopropanation, which is induced by the allenic unit and it involves the initial nucleophilic attack of the central carbon of the unsaturated Ru-C3 chain at the central carbon atom of the allenic unit.

The propargyl-allenic isomerization involves

a 1,3-hydrogen shift within the substituent of the amine. To block this process, we have carried out the reaction of 1 with 1,1-diethylpropargylamine, which does not contain hydrogen atoms in α-position with regard to the nitrogen atom. In dichloromethane, the reaction leads to the dihydropyridiniumyl derivative 4 (eq. 2). Its formation involves the selective N,Cγ addition of the amine to the Cα-Cβ double bond of the allenylidene ligand of 1.

In contrast to 1,1-diethylpropargylamine but

in agreement with propargylamine, the N-H bond of N-methylpropargylamine is added to the Cα-Cβ double bond of the allenylidene ligand of 1, to afford the tertiary azoniabutadienyl derivative 5, which was isolated as a mixture of the isomers 5a and 5b (eq. 3). Treatment at –78ºC of tetrahydrofuran solutions of the isomeric mixture with sodium methoxide gives a 1:1 mixture of the dihydronaphtopyrrolyl diastereomers 6a and 6b.

The new polycycle is the result of two carbon-carbon couplings in 5, the Cβ atom of the original C3 chain with the central carbon atom of the propargyl unit and, at the same time, an ortho carbon atom of one of the phenyl groups with the terminal (C(sp)) atom. These couplings can be rationalized as an intramolecular Diels-Alder reaction in an allenyl-amino-diphenyallenyl intermediate, where the Cβ-Cγ double bond and one of the two phenyl groups of the

[Ru]

Ph

N

Ph

HHO-

- H2O

[Ru] N

Ph

Ph

+

[Ru] ≡ [Ru(η5-C5H5)(CO)(PiPr3)]

1

2 3

(1)H2N

[Ru]=C=C=C+ Ph

Ph


1

H2N

Et Et[Ru] N +

H

EtEtPh

Ph 4

(2)

26

diphenylallenyl fragment act as an inner-outer ring diene and the C=CH2 double bond of the another allenyl fragment acts as a dienophile. The formation of two diastereomers in the reaction is the consequence of the chirality of the ruthenium and the two possible approaches of the dienophile to the diene.

Diallylamine, which contains C-C double

bonds instead of a C-C triple bond, reacts in a similar manner to propargylamine and N-methylpropargylamine. The addition of this organic substrate to 1 leads to the tertiary N-allyl-4-azonia-1,3,6-heptatrienyl derivative 7 (eq.4), as a result of the addition of the N-H bond of the amine to the Cα-Cβ double bond of the allenylidene. In the presence of bases, there are marked differences in behavior between the previously described azonia derivatives and 7. In contrast to the general trend, the deprotonation of 7 does not occur at the CH=CPh2 group but at one of the NCH2-carbon atoms. Although the allyl units are inequivalent, the deprotonation of both moieties is equally favored. As a result, the treatment of 7 with sodium methoxide in tetrahydrofuran affords a 1:1 isomeric mixture of the ruthenapyrrolinone complex 8 and the pyrrolinyl compound 9.

The formation of 8 involves the deprotonation

of the allyl group disposed trans to the CH=CPh2 unit, followed by the intramolecular attack of the deprotonated NCH-carbon atom to the carbonyl ligand. Complex 9 is the result of the deprotonation of the allyl group trans disposed to the metallic center and the subsequent intramolecular nucleophilic attack of the deprotonated NCH-carbon atom to the CPh2-carbon atom of the CH=CPh2 moiety. Both the formation of 8 and 9 can be rationalized as dipolar 1,5-electrocyclizations.

The high degree of stereocontrol in the formation of 8 and 9 should be pointed out. As a result of the prochirality of the NCH2 carbon atoms, two pairs of enantiomers of each isomer could be formed during the reaction. However, only one pair of 8 and one pair of 9 are obtained. This suggests that the configuration of the ruthenium atom of 1, and therefore of 7, determines the configuration of the asymmetric NCH-carbon atom of the heterocyles of 8 and 9.

Complex 9 reacts with tetrafluoroboric acid to give the cationic derivative 10 (eq. 5). The latter, which is an isomer of 7 is the result of the addition of the proton of the acid to the Cβ atom of 9. In the solid state, complex 10 is stable at room temperature. However in dichloromethane as solvent, it evolves to afford 11. The process involves the opening of the five-membered hetero-ring, formally as a consequence of the split of the CPh2-CH(vinyl) bond, along with a proton transfer from Cβ to the terminal carbon atom of the vinyl substituent.

Today is rare to find a complete total

synthesis that does not use a transition-metal-based reaction. In this respect, carbene complexes are one of the most useful tools. The reactions shown here indicate that the potentiality of the allenylidene compounds can become greater than that of carbene complexes of type LnM=CR2. The preparation of transition-metal allenylidene derivatives is very easy 6, and the presence of three reactive centers (unsaturated C3 chain) or more (unsaturated chain plus substituents) in the η1-carbon ligand allows one to build, in one or two steps, organic skeletons, which require multistep procedures in conventional organic synthesis. Principal publications M. L. Buil, M. A. Esteruelas, A. M. López, E. Oñate. Organometallics 2003, 22, 162; ibid. Organometallics 2003, 22, 5274.

Acknowledgements We are grateful for financial support from the MCYT of Spain (Projects BQU2002-00606 and PPQ2000-0488-P4-02) M.L.B. thanks the Ministerio de Ciencia y Tecnología (CICYT) of Spain for a Ramón y Cajal project. References 1 I. Bytschkov, S. Doye. Eur. J. Org. Chem. 2003, 935. 2 C. G. Hartung, A. Tillack, H. Trauthwein, M. Beller. J. Org. Chem. 2001, 66, 6339. 3 M. I. Bruce. Chem. Rev. 1991, 91, 197. 4 M. P. Gamasa, J. Gimeno, B. Martín-Vaca, J. Borge, S. García-Granda, E. Pérez-Carreño. Organometallics 1994, 13, 4045. 5 M. A. Esteruelas, A. V. Gómez, A. M. López, J. Modrego, E. Oñate. Organometallics 1997, 16, 5826. 6 J. P. Selegue. Organometallics 1982, 1, 217.

+

7

N Ph

Ph[Ru]

[Ru]

8

N Ph

Ph

9

N Ph

Ph

O

[Ru]S

S

S

R

[Ru] ≡ [Ru(η5-C5H5)(PiPr3)]

OC

OCHN(CH2CH=CH2)

1CH3O-

- CH3OH

+

(4)

9

10

N Ph

Ph

11

N Ph

Ph

r.t.

[Ru]HBF4

[Ru]CH2Cl2

+ +


(5)

[Ru]

Ph

Ph

+N

Ph

CH3

[Ru]

H

NH1

5a 6a

[Ru]

Ph

N

Ph

CH3+

H

5b

CH3N

H

6b

+ +(3)CH3O-

- CH3OH

N

Ph

CH3

[Ru]

H


27

A BICYCLIC ANALOGUE OF PROLINE STABILISES THE βI-TURN PEPTIDE CONFORMATION

A. M. Gil, E. Buñuel, A. I. Jiménez, C. Cativiela

Small and medium-sized peptides are

usually characterised by a high conformational freedom. This flexibility precludes their use as medicinal agents since the various conformers available may interact with multiple receptors and thus lead to undesired side effects. Reduction of the peptide backbone flexibility through the stabilisation of secondary structure elements constitutes a major approach in the design of therapeutically useful peptides as well as in the investigation of structure-activity relationships.

Among the elements of secondary structure usually found in peptides and proteins, β-turns are of enormous significance not only from a structural viewpoint but also regarding biological activity. β-Turns involve four consecutive residues and are classified according to the (φ,ψ) dihedral angles of the central i+1 and i+2 positions. Types I and II β-turns, which are the most widely distributed, are characterised by all trans peptide bonds and generally stabilised by an intramolecular hydrogen bond between the i and i+3 positions.

Because of its cyclic nature, proline (Pro) is the most conformationally constrained of the proteinogenic amino acids, and this property makes it a key residue both in peptide conformation and biology. The N–Cα torsion angle (φ) in proline is intrinsically restricted to near –60° and, accordingly, proline is most frequently found at the i+1 position of types I and II β-turns. In the βI-turn the ψ angle of proline (Cα–CO torsion) lies in the –30° region, whereas the βII-turn is characterised by ψ around 130°. Dipeptides of L-Pro-L-Xaa sequence typically adopt a βI-turn in low-polarity solvents but, in general, this conformation is not retained in the crystalline state, where the βII-turn disposition is preferred because it allows intermolecular hydrogen-bonding of the Xaa NH site 1.

Figure 1: Structure of proline (Pro) and its bicyclic analogue studied in this work (Phb7Pro).

We have evaluated the relative stability of the βI- and βII-turns in model peptides RCO-L-Pro-L-Phe-NHR' when phenylalanine was replaced by different constrained derivatives 2-4. Now, we have undertaken the replacement of the proline residue in this sequence by a bicyclic analogue of norbornane structure. In the proline surrogate considered, that we denote as Phb7Pro (Fig. 1), the flexibility of the pyrrolidine ring has been frozen by connecting the α- and δ-carbons through an ethylene bridge.

Additionally, a phenyl substituent, which can interact with the backbone both electronically and sterically, has been introduced on the β-carbon.

Figure 2: Structure of the dipeptide studied, incorporating the bicyclic analogue of L-proline in position i+1.

The norbornane proline analogue Phb7Pro

was incorporated into the PhCO-Phb7Pro-L-Phe-NHiPr sequence (Fig. 2) 5 following standard methods of peptide synthesis. This dipeptide yielded single crystals that were subjected to X-ray diffraction analysis. The crystalline structure obtained is shown in Fig. 3. The molecule is folded in a β-turn, with an intramolecular hydrogen bond between the benzoyl oxygen and the isopropylamide hydrogen (N...O distance 2.89 Å, N–H...O angle 159°), and the backbone torsion angles correspond to a type I β-turn. This is highly remarkable since the analogous dipeptide tBuCO-L-Pro-L-Phe-NHMe is not able to retain the βI-turn conformation in the solid state, where it has been shown to accommodate a βII-turn disposition 6. It should be emphasised that in the crystal structure of PhCO-Phb7Pro-L-Phe-NHiPr the phenylalanine amide proton is not involved in any intermolecular contact, whereas in the L-Pro-containing dipeptide this middle NH is hydrogen-bonded to a carbonyl group of a neighbouring molecule.

βI-turn

Phb7Pro (φ,ψ) = (–46,–31)

L-Phe

(φ,ψ) = (–73,–12)

Figure 3: X-ray diffraction structure of the PhCO-Phb7Pro-L-Phe-NHiPr dipeptide, showing a βI-turn conformation with an intramolecular i+3 to i hydrogen bond.

This result evidences that Phb7Pro exhibits a

propensity for βI-folding higher than that of proline. Several factors can contribute to it.

28

The three amide bonds in Fig. 3 present a trans disposition with the torsion angles ω close to the standard ±180°. However, the nitrogen atom in the 7-position of the norbornane moiety exhibits a significant distortion from planarity, lying at a distance of 0.38 Å from the plane defined by the three carbon atoms bonded to it. In fact, the pyramidal character of this nitrogen has been highlighted as an intrinsic feature of the tensioned 7-azanorbornane system 7. In the case considered here, this out-of-plane deviation is particularly strong, as denoted by the sum of the valence angles around the nitrogen (339°) in comparison to the value expected for a planar trigonal arrangement (360°).

The marked pyramidal geometry of this tertiary nitrogen confers it a pronounced sp3 character and hampers delocalization of the lone pair to the adjacent carbonyl group. As a consequence, a significant lengthening of the N–CO bond (1.38 Å) is observed with respect to the standard amide value (1.33 Å). At the same time, the higher accessibility of the lone pair allows the nitrogen to act as a weak hydrogen-bond acceptor. Thus, in the crystalline structure shown in Fig. 3, the phenylalanine amide hydrogen points towards the lone pair of the pyramidalised nitrogen (H...N distance 2.59 Å, N...N distance 2.92 Å), giving rise to an N–H...N attractive interaction. Interestingly, an interaction of this type has been proposed to promote the cis-trans isomerization of the amide bond preceding proline by stabilising the lone pair of the pyramidalised proline nitrogen in the transition state 8. It should be noted that ψ values for the bicyclic proline surrogate in the 130° region (corresponding to the i+1 position of a βII-turn) would not allow the establishment of this N–H...N interaction. In fact, a βII-turn disposition for this dipeptide would place the Phb7Pro carbonyl oxygen in the neighbourhood of the pyramidalised nitrogen lone pair, thus introducing a repulsive interaction.

An additional factor that can contribute to the stabilisation of the βI-turn conformation encountered for PhCO-Phb7Pro-L-Phe-NHiPr is the presence of the extra β-phenyl substituent in the bicyclic analogue of proline. In the structure shown in Fig. 3, this exo-oriented phenyl ring lies in close proximity to the phenylalanine amide hydrogen, giving rise to an attractive interaction of the N–H...π type. Amide-aromatic interactions have been frequently cited as stabilising factors in the structure of peptides and proteins 9. Again,

such an interaction would not occur in a βII-turn disposition.

Another remarkable feature in Fig. 3 is the gauche(+) disposition adopted by the phenylalanine side chain (χ1 = 58°). This is the least common of the three staggered rotamers available to this residue, because of steric hindrance between the phenyl ring and both the amino and carbonyl substituents. However, this orientation allows the existence of an additional amide-aromatic interaction between the phenylalanine amide hydrogen and phenyl side chain.

The βI-turn conformation accommodated by the Phb7Pro-containing dipeptide in the crystalline state provides evidence that the extra attractive intramolecular interactions involving the bicyclic proline analogue and the middle amide hydrogen compensate for the intermolecular hydrogen bond that stabilises the βII-turn conformation in the L-Pro-L-Phe sequence. Proline analogues, as the one presented here, that are able to stabilise the βI-turn disposition are extremely helpful in the design of peptide analogues with well-defined conformational features. Principal publication A. M. Gil, E. Buñuel, A. I. Jiménez, C. Cativiela. Tetrahedron Lett. 2003, 44, 5999. Acknowledgements Financial support was provided by MCyT (PPQ2001-1834 and PPQ2002-819). The Centro de Excelencia Bruker-ICMA is gratefully acknowledged for collection and preliminary treatment of the X-ray diffraction data. References 1 M. Marraud, A. Aubry, Biopolymers 1996, 40, 45. 2 A. I. Jiménez, C. Cativiela, A. Aubry, M. Marraud. J. Am. Chem. Soc. 1998, 120, 9452. 3 A. I. Jiménez, C. Cativiela, J. Gómez-Catalán, J. J. Pérez, A. Aubry, M. París, M. Marraud, J. Am. Chem. Soc. 2000, 122, 5811. 4 A. I. Jiménez, C. Cativiela, M. Marraud. Tetrahedron Lett. 2000, 41, 5353. 5A. M. Gil, E. Buñuel, P. López, C. Cativiela. Tetrahedron Asymmetry 2004, 15, 811. 6 A. Aubry, M. T. Cung, M. Marraud. J. Am. Chem. Soc. 1985, 107, 7640. 7 Y. Otani, O. Nagae, Y. Naruse, S. Inagaki, M. Ohno, K. Yamaguchi, G. Yamamoto, M. Uchiyama, T. Ohwada. J. Am. Chem. Soc. 2003, 125, 15191. 8 G. Fischer. Chem. Soc. Rev. 2000, 29, 119. 9 T. Steiner, G. Koellner. J. Mol. Biol. 2001, 305, 535.

29

NUCLEOSIDE ANALOGUES: FUTURE OF CHEMOTHERAPEUTIC AGENTS

P. Merino, T. Tejero, F. L. Merchán, S. Franco, P. Romero, J. A. Matés, V. Mannucci Bioorganic Chemistry Research Group

In the therapy of infections caused by viruses

and also in the treatment of certain neoplastic diseases, nucleoside analogues have emerged as major chemotherapeutic agents. Since the discovery that nucleoside analogues can effectively protect cells from the lethal action of some viruses, including the human immunodeficiency virus (HIV), herpes simplex virus, hepatitis C virus and cytomegalovirus, among others, several reviews have appeared concerning their synthesis, therapeutic applications and mechanism of action. The majority of nucleoside analogues consist of modifications of natural substrates in the heterocyclic base or the sugar moiety. The general structure of a nucleoside analogue is well-defined by three key elements: i) the hydroxymethyl group, which is needed for activation through phosphorylation by kinases, ii) the heterocyclic base, which is needed for the recognition by the enzymes and the complementary strand in the nucleic acid synthesis process, and iii) the spacer, (the furanose ring in natural compounds) which present the two former groups in the adequate disposition. In this respect, it is interesting to speculate that the biological effects exhibited by nucleoside analogues depend importantly on the relative disposition of the hydroxy methyl group and the base moiety.

Y

spacer

HON

XH

Z

n

hydroxymethylgroup

heterocyclicbase

Figure 1. General structure of a nucleoside Due to the high specifity of 5’-

phosphorylating kinases only a few variations are allowed regarding the hydroxymethyl group. There are a vast family of compounds grouped under the name of nucleoside antibiotics that present complex side chains instead of the hydroxymethyl group. Hydrogen bond interactions of heterocyclic bases are fundamental for the biological activity of nucleoside analogues. So, any variation of the base moiety should preserve such intramolecular forces. As a consequence, only minor variations of bases are found in biologically active nucleoside analogues. The most notable of that sort of structural modifications is found in C-nucleosides, in which the typical C-N glycosidic bond has been replaced by a non-hydrolizable C-C bond.

On the other hand, numerous variations are possible for the spacer whilst still retaining

activity. The relative 1’,4’ disposition of the hydroxymethyl group and the heterocyclic base can also be modified in order to obtain the so-called isonucleosides, compounds from both D- and L- enantiomeric series that have shown antiviral activities.

The structural modifications of the spacer backbone also led to active compounds. Replacement of the furanose ring by an acyclic chain, which can adopt a conformation similar to conventional nucleosides, gives rise to the acyclonucleosides, from which acyclovir, gancyclovir and their prodrugs are the best known. The furanose ring can also be replaced by a different carbo or heterocyclic ring. The carbocyclic analogues are also relevant compounds. Pyranosyl nucleoside analogues have also been proposed an alternative to conventional nucleosides in oligonucleotide chains. The corresponding analogues having a four-membered ring (oxetane) instead the conventional furanose ring have also been considered.

Figure 2. Antiviral drugs

The interest in nucleoside analogues in which the furanose ring is replaced by a different heterocyclic ring (heterocyclic nucleosides) has appeared much more recently. It is the aim of the group of Bioorganic Chemistry to study and develop the methodologies for the construction of those novel nucleoside analogues. More complex nucleosides such as polyoxins and nikkomycins are also studied in our group. In particular, the polyoxins are a group of peptidyl nucleoside antibiotics produced in the fermentation broth of Streptomyces cacaoi var asoensis and that have been isolated and characterized by Isono and co-workers about thirthy years ago. In total, about fifteen compounds having closely related structures have been identified and designated with alphabetical letters. Their structure showed the presence of a unique ribofuranosyl α-amino acid nucleoside that constitutes the common skeleton to all of the members of the family. The nucleoside portion that eventually bears different pyrimidine bases is connected through amidic bonds to an open chain polyalkoxy α-amino acid and to an azetidine-2-carboxylic acid. This tripeptide structure is illustrated by the first member of the family, polyoxin A. Some polyoxins however are simply dipeptides

30

incorporating in their structure only two of the above amino acids. This is the case of polyoxin J that in fact by hydrolytic degradation leads to the polyalkoxy α-amino acid 5-O-carbamoyl-polyoxamic acid and the amino acid nucleoside thymine polyoxin C.

R1HNCO2R3

O

HO OH

N

NHR2

O

O

H, CH3, CH2OH, CO2HR2:

OH

Me

NH2

O

XR1:

OH, N

CO2H

R3:

H, OHR4:

H2N O

O

OH

R4

NH2

O

R1:

HR2:

X:

OHR3:

N, CH

Polyoxins Nikkomycins

Figure 3. General structure of Polyoxins

The original interest for polyoxins and the closely related natural products nikkomycins and neopolyoxins as well as their synthetic analogues stemmed from their marked activity against phytopathogenic fungi whereas are non toxic to bacteria, plants, or animals. These biological effects apparently are due to the ability of polyoxins to inhibit the enzyme chitin synthase and therefore to prevent the biosynthesis of chitin, an essential component of the fungal cell wall structure. Hence, the polyoxin complex obtained by fermentative processes proved to be an excellent agricultural fungicide of wide use, particularly for the sheath blight disease of rice plant. More recently, considerable attention to all the above families of peptidyl nucleosides antibiotics, especially nikkomycins and neopolyoxins has been addressed as inhibitors of opportunistic fungal infections by Candida albicans in immuno-compromised hosts, such as AIDS victims and organ transplant patients.

Candida albicans

treated untreated

Figure 4. Differences in the cell wall of “Candida Albicans” upon treatment with polyoxins From natural sources it is only possible to isolate typical furanose-containing compounds whereas

in order to improve the activity novel analogues are needed. Due to the differences found in the biological activities of polyoxins and nikkomycins when measured against the enzyme (chitin synthase) and Candida albicans in culture it is of high interest to prepare new analogues which could be more effective as anticandidal agents. In this regard the Bioorganic Chemistry group of ICMA has also been paid attention to the synthesis of structural analogues of polyoxins and nikkomycins.

Figure 5. Commercial sources of Polyoxins

In our laboratory is an ongoing program aimed at demonstrating the versatility of chiral nitrones and hydroxylamines as building blocks for the efficient construction of biologically interesting nitrogenated compounds. In particular, we are interested in the synthesis of isoxazolidinyl nucleosides, the class of nucleoside analogues in which the furanose ring has been replaced by an isoxazolidine ring. Our experience in organic synthesis allows us to suggest that isoxazolidinyl nuleoside analogues of complex nucleosides can be synthesized by applying our nitrone-based methodology. Thus our goal is to design novel isoxazolidinyl analogues of both conventional nucleosides and complex nucleosides including nucleoside antibiotics such as polyoxins and nikkomycins. Acknowledgements We thank for their support the Ministry of Science and Technology (MCYT, Spain) and FEDER Program (Project CASANDRA, BQU2001-2428) and the Government of Aragon (Project P116-2001). References 1 P. Merino, S. Franco, F. L. Merchán, J. Revuelta, T. Tejero. Tetrahedron Lett. 2002, 43, 459. 2 P. Merino, J. Revuelta, T. Tejero, U. Chiacchio, A. Rescifina, A. Piperno, G. Romeo. Tetrahedron Asymmetry 2002, 13, 167. 3 P. Merino, A. Piperno, A. Rescifina, G. Romeo, R. Romeo, T. Tejero. Tetrahedron 2003, 59, 4733. 4 P. Merino, S. Franco, D. Lafuente, F. L. Merchán, J. Revuelta, T. Tejero. Eur. J. Org. Chem. 2003, 2877. 5 P. Merino, T. Tejero, M. Laguna, E. Cerrada, A. Moreno, J. A. López. Org. Biomol. Chem. 2003, 1, 2336. 6 P. Merino, S. Franco, F. L. Merchán, P. Romero, T. Tejero, S. Uriel. Tetrahedron Asymmetry 2003, 14, 3731.

31

“GREENING” THE CHEMISTRY THROUGH CATALYSIS

J. M. Fraile, J. I. García, J. A. Mayoral

Although Chemistry is perceived as a pollutant activity, many chemists are involved in the development of cleaner products and processes, which allow the sustainability and the economical growth without compromising the environment, in the field known as “green chemistry”. Catalysis is probably one of the most valuable tools for this purpose, because it allows a better use of the starting materials (higher conversion), lower energy consumption and a lower waste generation due to the higher selectivity of the process. The use of heterogeneous catalysis results additionally advantageous because of the easiness of separation, recycle and reuse.

As base of this philosophy, “green chemistry” must be economically attractive for the industry, given that all the objectives have an impact on lowering the costs of production. In fact, several industries are involved in this type of research 1,2, trying for example the substitution of strong mineral acids, such as sulfuric or hydrochloric acids, by solid acids which minimize the corrosion problems, allowing at the same time an easier storage and handling.

One of the main pollution sources in the chemical industry is the generation of by-products, inherent to the use of specific reagents. One clear example is the oxidation reactions. The use of potassium dichromate brings inherent the production of chromium salts and oxides. When epoxides are considered, the most popular oxidants are peracids, such as meta-chloroperbenzoic acid, but the corresponding acid is produced as stoichiometric by-product. Because of that the most suitable oxidants are molecular oxygen and hydrogen peroxide. As oxygen usually requires a sacrificial reductant, such as an aldehyde, hydrogen peroxide remains as one of the most promising alternative, given that the only by-product generated is water. However, a catalyst is necessary in order to activate hydrogen peroxide and the requirements of this catalyst are quite exigent, as it must work in the presence of water. This is not especially difficult in the case of electrophilic alkenes, as the activation of hydrogen peroxide is carried out with a base 3. Within the research line devoted to the development of basic solid catalyst, the use of natural phosphate from Morocco has shown a high potential interest, due to its low cost and high activity in several reactions 4, with the additional advantage of low solvent requirements. However the epoxidation of nucleophilic alkenes requires the activation of hydrogen peroxide with a Lewis acid, a not easy task in the presence of water. In contrast with previous ideas, our group was able to activate diluted (30%) hydrogen peroxide with easily prepared silica-supported titanium catalysts (Figure 1). These catalysts are

highly modular and are prepared by reaction of the silica support with Ti(OiPr)4 as a titanium precursor, under soft conditions. The nature of the support plays an important role, together with the titanium dispersion.

O

OTi

OXOiPr

SILI

CA

O

O

SILI

CA

Ti(OiPr)4

OH

H

H

OH

(X = iPr or H)

O

O

SILI

CA

O

H

H

SiMe2R

O

OTi

OXOiPr

SILI

CATi(OiPr)4

OSiMe2R

Hydrophobic silica

Hydrophilic silica

Figure 1: Synthesis of silica-supported titanium catalysts.

Additional modifications can be introduced on the environment of titanium by substitution of the remaining isopropoxide groups by diols, aminoalcohols and diamines 5. The modification of the Lewis acidity of the titanium centres, as shown by experimental NH3 desorption and theoretical calculations, does not only modify the epoxidation activity, but also the selectivity to epoxide due to changes in the hydrolysis activity and the participation of the radical allylic oxidation mechanism.

O

O

OH

OH

OOH OH

+

[Ti]

[Ti]

[Ti]

[Ti]H2O

H2O [Ti]

H2O2

H2O

2 H2O2

2 H2O

direct epoxidation

radical pathway

hydrolysis

Figure 2: Mechanisms of epoxidation with H2O2.

In spite of all the improvements introduced by the catalyst design, the most important step towards the practical application of this method is the optimization of the reaction conditions 6. The slow addition of hydrogen peroxide drastically reduces the rate of decomposition, and as a consequence the molecular oxygen concentration in the reaction medium. In this way the radical allylic oxidation is minimized (Figure 2) and the epoxide hydrolysis remains as the only problem to be solved.

Methods for the characterization of the titanium sites are currently under development,

32

together with the study of the structure-activity relationships.

The easiness of recovery of heterogeneous catalysts is especially interesting in the case of high cost catalysts, as asymmetric ones. The chiral ligands are usually expensive or even no commercially available, and then the recycle of the catalyst, with the improvement in productivity, represents an important saving in investment. The covalent grafting, which ensures the chiral ligand recovery, is probably the best established immobilization method for asymmetric catalysts. The development of methodologies for grafting of ligands of general application are highly interesting, given that they open the way to a large variety of chiral catalysts. This is the case of pyridinebis(oxazolines), tridentate ligands able to coordinate metals such as ruthenium, rhodium or lanthanides. The introduction of spacers in the position 4 of the pyridine ring (Figure 3) allows the easy grafting on organic 7 and inorganic supports 8. After the preliminary test on the cyclopropanation reaction, other applications are currently under development.

N NNO O

R R

SUPPORT

Figure 3: Immobilization of pyridinebis(oxazoline).

In this type of immobilization, the accessibility of the ligand is crucial for an efficient complexation with the metal precursor. When this complexation is difficult, an important part of the expensive ligand remains useless. Thus, even in the case of a high productivity per metal site, the productivity per chiral ligand is low, a term we called “ligand economy” 9. In this regard, the morphology of the support plays a decisive role. In the case of polymerized chiral ligands, the composition of the monomeric mixture and the polymerization solvent are the most important factors. We demonstrated that dendrimers can act as more efficient cross-linking agents, conferring to the polymer a more open structure which allows a better ligand economy 10.

In spite of the cited advantages, the covalent grafting of chiral ligands requires a (sometimes) hard synthetic work in the modification of the ligand. Moreover, the functionalization of the chiral ligand with a very bulky substituent, as it is the solid support, leads in many cases to a drastic reduction of the enantioselectivity. Trying to prevent this problem, our group has been working in the immobilization of cationic complexes by electrostatic interactions with anionic supports. In such case, the metal carrying the positive charge is strongly hold by the support, but we detected some ligand leaching due to competitive complexation with

reaction products and by-products. This problem is currently be solved by using analogue ligands which bind more strongly the metal centre 11.

Although it is considered that the support-ligand steric interaction is weaker in the case of catalysts immobilized through electrostatic interactions, this is not the case when layered materials, such as clays, are used as supports. The dielectric constant of the reaction solvent modifies the relative position of the complex and the clay surface, and hence the steric interaction between them. Thus it is possible to design chiral ligands specifically to be used under such conditions, taking advantage of this interaction. In a preliminary work this possibility has been demonstrated 12 but further improvements are being currently done.

In conclusion, the application of heterogeneous catalysts to the fine chemicals synthesis allows the development of cleaner processes, through substitution of harmful homogeneous acids and bases, the use of cleaner reagents and the efficient recovery and reuse of the catalyst. In some cases the heterogeneous character even modifies the selectivity of the catalyst, leading to interesting new properties.

Acknowledgements Financial support for this work was provided by the Spanish CICYT (projects MAT99-1176, PPQ2000-0322-P4 and PPQ2002-04012) and the DGA. References 1 C. Cativiela, J. M. Fraile, J. I. García, B. Lázaro, J. A. Mayoral, A. Pallarés. Appl. Catal. A 2002, 224, 153. 2 C. Cativiela, J. M. Fraile, J. I. García, B. Lázaro, J. A. Mayoral, A. Pallarés. Green Chem. 2003, 5, 275. 3 J. M. Fraile, J. I. García, J. A. Mayoral, S. Sebti, R. Tahir. Green Chem. 2001, 3, 271. 4 S. Sebti, A. Solhy, R. Tahir, S. Abdelatif, S. Boulaajaj, J. A. Mayoral, J. I. García, J. M. Fraile, A. Kossir, H. Oumimoun. J. Catal. 2003, 213, 1. 5 J. M. Fraile, J. I. García, J. A. Mayoral, L. Salvatella, E. Vispe, D. R. Brown, G. Fuller. J. Phys. Chem. B 2003, 107, 519. 6 J. M. Fraile, J. I. García, J. A. Mayoral, E. Vispe, Appl. Catal. A 2003, 245, 363. 7 A. Cornejo, J. M. Fraile, J. I. García, E. García-Verdugo, M. J. Gil, G. Legarreta, S. V. Luis, V. Martínez-Merino, J. A. Mayoral. Org. Lett. 2002, 4, 3927. 8 A. Cornejo, J. M. Fraile, J. I. García, M. J. Gil, V. Martínez-Merino, J. A. Mayoral. Molecular Diversity 2003, 6, 93. 9 M. I. Burguete, E. Díez-Barra, J. M. Fraile, J. I. García, E. García-Verdugo, R. González, C. I. Herrerías, S. V. Luis, J. A. Mayoral. Bioorg. Med. Chem. Lett. 2002, 12, 1821. 10 E. Díez-Barra, J. M. Fraile, J. I. García, E. García-Verdugo, C. I. Herrerías, S. V. Luis, J. A. Mayoral, P. Sánchez-Verdú, J. Tolosa. Tetrahedron Asymmetry 2003, 14, 773. 11 J. M. Fraile, J. I. García, M. A. Harmer, C. I. Herrerías, J. A. Mayoral, O. Reiser, H. Werner, J. Mater. Chem. 2002, 12, 3290. 12 A. Cornejo, J. M. Fraile, J. I. García, M. J. Gil, C. I. Herrerías, G. Legarreta, V. Martínez-Merino, J. A. Mayoral. J. Mol. Catal. A 2003, 196, 101.

33

C-H ACTIVATION/FUNCTIONALIZATION SEQUENCES IN DIIRIDIUM COMPLEXES

E. Sola, M. V. Jiménez, Y. Yuan, F. J. Lahoz, L. A. Oro

“What one metal can do, two metals can do better”

Considering our present understanding of the

structure/reactivity relationships in di- and polynuclear metal compounds, this sentence, often found in articles, reviews and monographs, should be better regarded as the formulation of a reasonable expectation rather than as a fact.

Indeed, the chemical literature contains several particular examples describing unusual, sometimes extraordinary, chemical transforma-tions which can be eventually attributed to the presence of two or more metal atoms in close proximity. However, references can also be found describing polymetallic complexes that fail to give reactions easily achievable by related mononuclear species. This indicates that the chemistry of polynuclear compounds should be expected to differ from that of mononuclear relatives, although, not surprisingly, the differen-ces cannot always result into advantages. Due to this, the practical exploitation of this chemistry seems unlikely without a previous effort to further understand the peculiar chemistry of multimetallic sites and the mechanisms of inter-metallic cooperation.

Aimed at this goal, we initiated a systematic reactivity study of simple and NMR accessible dinuclear compounds of iridium such as those shown in Chart 1. Investigation of complex 1 led to the characterization of a mechanisms for intermetallic communication based on the transmission of trans effects 1, which effectively operates in fast and selective catalytic hydrogenation cycles 2. In contrast, the study of complex 2 and related compounds revealed the inadequacy of such open-book dinuclear Ir(I) compounds for simple concerted activations that readily take place at parent mononuclear derivatives.

Chart 1. Dinuclear iridium complexes typically used along this investigation.

Due to our interest in C-H activations of

potential use for small molecule functionaliza-tion, we explored possible strategies to over-come the inertness of these Ir(I) dinuclear compounds toward concerted C-H oxidative additions. The rich chemistry of these complexes provided several successful ways by which their activation capability could be experimentally enhanced. In particular, we did the very counter-intuitive observation that oxidation of the com-

pounds favors the oxidative addition of C-H bonds (Chart 2) 3.

Chart 2: Alkene C-H activations at dinuclear complexes can be promoted by oxidation.

The rationalization of this fact and other com-

plementary results in the frame of the molecular orbital description of such dinuclear Ir(I) compounds concluded that the simplest require-ment to get C-H activating compounds is the breaking of their symmetry, since such operation is enough to liberate an empty orbital from the weak, but highly deactivating, metal-metal interactions existing in these compounds 4.

A straightforward application of this conclu-sion has involved the use of bridging ligands that can asymmetrically coordinate the diiridium moiety. As can be seen in Chart 3, the asym-metric arrangement of such ligands led to complexes promoting C-H activation / insertion sequences of ethylene.

Chart 3. Asymmetric bridging systems promote C-H activation / insertion reaction sequences with ethylene.

The generalization and further development

of this strategy to achieve other reaction sequences in route to catalytic functionalization processes in under current investigation. Principal publication Y. Yuan, M. V. Jiménez, E. Sola, F. J. Lahoz, L. A. Oro. J. Am. Chem. Soc. 2002, 124, 752.

Acknowledgements “Catálisis homogénea por complejos de metales de transición” (BQU2000-1170). References 1 E. Sola, F. Torres, M. V. Jiménez, J. A. López, S. E. Ruíz, F. J. Lahoz, A. Elduque, L. A. Oro. J. Am. Chem. Soc. 2001, 123, 11925. 2 F. Torres, E. Sola, A. Elduque, A. P. Martínez, F. J. Lahoz, L. A. Oro. Chem. Eur. J. 2000, 6, 2120. 3 M. V. Jiménez, E. Sola, J. Caballero, F. J. Lahoz, L. A. Oro. C. Angew. Chem. Int. Ed. 2002, 41, 1208. 4 L. A. Oro, E. Sola in Recent Advances in Hydride Chemistry, M. Peruzzini, R. Poli (Eds.), Elsevier, 2001, p. 299.

34

DISCRETE MIXED-VALENCE IRIDIUM CHAINS

C. Tejel, M. A. Ciriano, B. E. Villarroya, J. A. López, F. J. Lahoz, L. A. Oro

Compounds containing discrete chains of metal-bonded atoms are highly interesting not only from a theoretical point of view, but also because of their potential applications, particularly as candidates for nanoscale electronic devices. Reproducible and well-defined syntheses for these compounds include ligand-assisted reactions of metal compounds with conjugated polyenes 1 and with polydentate ligands, such as oligo-α-pyridylamino ligands 2. In these cases, the number of available coordination sites of the ligand determines the length of the metallic chain.

Our approach to the synthesis of discrete metal-chains of iridium, which are mostly unknown 3, is different from the above described systems. It involves the oxidation of dinuclear complexes of d8 square-planar metal centers to form metal-metal bonds between two dinuclear units, which leads to a spontaneous linear condensation. This methodology has, in principle, no other limitations on the growing of the metallic chain length than the thermodynamic stability of the products, provided that the steric encumbrance between the links is kept at minimal.

We have found that the binuclear complex [Ir2(µ-Opy)2(CO)4] (Opy = 2-pyridonate) is an appropriate precursor for discrete iridium chains. Thus, oxidation of [Ir2(µ-Opy)2(CO)4] with diiodine gave the unsymmetrical tetrametallic chain (HT,HH)-[Ir4(µ-Opy)4(I)2(CO)8][3] formed by a linear stack of HT-[Ir2(µ-Opy)2(I)(CO)4] and HH-[Ir2(µ-Opy)2(I)(CO)4] units with an fractional averaged oxidation state (+1.50) for the iridium atoms, as shown in Chart 1.

IrIr

CO

OCCO

OC

N OO N

Ir Ir

OC

OC

NNO

COCO

OII

(HT,HH)-[Ir(+1.5)4] Chart 1. Schematic representation of (HT,HH)-[Ir4(µ-Opy)4(I)2(CO)8]. The Opy ligands are represented as N-C-O for clarity.

The complex (HT,HH)-[Ir4(µ-Opy)4(CO)8] was

found to evolve to (HH,HH)-[Ir4(µ-Opy)4(CO)8] on heating, which shows the HH,HH configuration systematically found for the related tetranuclear platinum chains. What is remarkable here is the demonstration that, contrary to previous speculations, binuclear complexes with HT configurations are able to engage in tetrametallic chains. Moreover, with this experimental evidence, one can imagine the growing of unidimensional metallic chains through HT linkers, since they do not show steric hindrance along the direction of the metal-metal bond, allowing the entrance of new dinuclear units in

this axis. In fact, we were able to add a new HH link to the tetrametallic chain (HT,HH)-[Ir4(µ-Opy)4(CO)8] to form the hexametallic compound (HH,HT,HH)-[Ir6(µ-Opy)6(I)2(CO)12] by careful oxidation of [Ir2(µ-Opy)2(CO)4] with diiodine. The crystal structure of the new complex (Figure 1) revealed the almost linear array of the metals in which two HH-[Ir2(µ-Opy)2(I)(CO)4] units sandwich an HT-[Ir2(µ-Opy)2(CO)4] complex.

Figure 1. The almost linear array of metal atoms (in yellow) in the first hexanuclear iridium-chain. This 1-D oligomer is a molecular piece of a “metal-wire” related to the infinite mixed-valence metal chains, such as the Krogmann salts. Crystalline samples of the Ir complex have a copper-like appearence. (Taken from the Page Cover of Angew. Chem. Int. Ed.)

Noteworthy is also the fractional oxidation

state (+1.33) for the iridium atoms in the hexanuclear compound, which provides a new link in the electronic sequence connecting dinuclear Ir(I) and Ir(II) compounds:

{Ir(+1)}2 {Ir(+1.33)}6 {Ir(+1.5)}4 {Ir(+2)}2

Principal publication C. Tejel, M. A. Ciriano, B. E. Villarroya, J. A. López, F. J. Lahoz, L. A. Oro. Angew. Chem. Int. Ed. 2003, 42, 529.

Acknowledgements “Síntesis, estructura y reactividad de complejos mono- y poli-metálicos con posibles propiedades catalíticas o conducturas” (BQU2002-00074). References 1 T. Murahashi, T. Nagai, Y. Mino, E. Mochizuki, Y. Kai, H. Kurosawa. J. Am. Chem. Soc. 2001, 123, 6927. 2 R. Clérac, F. A. Cotton, T. B. Dunbar, C. A. Murillo, X. P. Wang. J. Am. Chem. Soc. 2000, 122, 2272. 3 C. Tejel, M. A. Ciriano, B. E. Villarroya, R. Gelpi, J. A. López, F. J. Lahoz, L. A. Oro. Angew. Chem. Int. Ed. 2001, 40, 4048.

35

VAPOCHROMIC COMPLEXES

E. J. Fernández, J. M. López de Luzuriaga, M. Monge, M. E. Olmos, J. Pérez, A. Laguna

Closed-shell interactions occur mainly for some heavy late transition metals and main-group elements. In fact, these are dispersion forces reinforced by relativistic effects and by ionic components, of which the former are maximized in heteronuclear interactions. Heteronuclear compounds containing gold(I) and group-11, -12, and -13 metals display d10-d10 or d10-s2 closed-shell interactions of intermediate strength relative to the homonuclear metal-metal interactions. The number of examples of gold(I)-gold(I) contacts is large, but representatives of heteronuclear gold(I)-metal contacts are still scarce. There are two general types of derivatives displaying short gold-metal distances -those with bridging ligands and those that are unbridged, of which the latter are always the more indicative of the presence of a real bond. Derivatives featuring unsupported gold-metal bonds have been obtained mainly through reactions between basic gold(I) complexes and acid complexes, and also by encapsulation of metal centers in metallocryptands. Most derivatives with supported gold-metal bonds have been synthesized by use of C-donor ligands or ambidentate ligands. The gold-metal contacts dramatically affect the conformations and the aggregation of the molecules, and also their optical properties. Some of these derivatives are, in fact, intensely luminescent 1.

The picture shows a disc that contains a suspension of the complex [(C6F5)2Au{µ-Ag(OClO3)}Au(C6F5)2] (solid) under ultraviolet light. The border of the disc is cooled with liquid nitrogen to a temperature close to 77 K and the centre of the disc is at room temperature. The luminescence and the colour of the complex

changes from red (near 77 K), through orange and yellow, to green (room temperature) 2. The complex {Tl[Au(C6Cl5)2]}n, displays a vapochromic behavior with reversible color changes when the solid is exposed to a variety of organic vapors. Acetone, acetonitrile, triethyl-amine, acetylacetone, tetrahydrothiophene (THT), 2-fluoropyridine, tetrahydrofuran (THF), and pyridine vapors (see Figure 2) have been used. The color changes back to that of the starting material upon heating to 100 °C over a period that requires from a few seconds for acetone to 10 min for pyridine. In all cases, the process is found to be completely reversible with no detectable degradation of the starting material after 10 exposure/heating cycles. The exchange of color is even deeper under UV light, and the substances display a strong luminescence under these conditions.

Figure 2. Powder samples of {Tl[Au(C6Cl5)2]}n, deposited on filter paper and exposed to selected organic vapors: (1) 2-flouropyridine, (2) THF, (3) acetone, (4) acetylacetone, (5) acetonitrile, (6) pyridine, (7) triethylamine, (8) THT. Principal publication E. J. Fernández, J. M. López de Luzuriaga, M. Monge, M. E. Olmos. J. Pérez, A. Laguna, A. A. Mohamed, J. P. Fackler. J. Am. Chem. Soc. 2003, 125, 2022.

Acknowledgements This work was supported by the Dirección General de Investigación (BQU2001-2409). References 1 M. Bardají, A. Laguna. Eur. J. Inorg. Chem. 2003, 3069. 2 E. J. Fernández, M. C. Gimeno, A. Laguna, J. M. López de Luzuriaga, M. Monge, P. Pyykkö, D. Sundholm. J. Am. Chem. Soc. 2000, 122, 7287.

37

Ciencia y Tecnología de Materiales

Materials Science and Technology

38

− Observation of discrete breathers in josephson arrays. J. J. Mazo.

− Lustre pottery: the secret of early nanomaterials revealed by transmission

electron microscopy. A. Larrea, J. Pérez-Arantegui.

− Ceramics for high temperature structural applications.

J. I. Peña, A. Larrea, R. I. Merino, I. de Francisco, P. B. Oliete, V. M. Orera.

− Hyscore spectroscopy of the cytochrome b559 of photosystem ll reaction centre. P. J. Alonso, J. I. Martínez.

− Enhanced anisotropy of nanosized Co clusters: effects from surface and inter-

particle interactions. F. Luis, J. M. Torres, L. M. García, J. Stankiewicz, J. Bartolomé, F. Petroff.

− A thiazyl-based organic ferromagnet: magnetism and spin-density distribution by

polarised neutron diffraction experiments and ab initio calculations. J. Campo, F. Palacio, J. Luzón, G. J. McIntyre, A. Alberola, J. M. Rawson, C. Paulsen, R. D. Farley.

− Towards the magnetic refrigeration: the magnetocaloric effect. A new method of

characterization with an adiabatic system. R. Burriel, E. Palacios, L. Tocado.

− Synchrotron X-ray resonant scattering in metallic oxides: charge and orbital

ordering. J. García, G. Subías, J. Blasco, M. G. Proietti, M. C. Sánchez, J. Herrero-Martin.

− New opportunities in trace elements structural characterization: high-energy X-

ray absorption near-edge structure spectroscopy. J. Chaboy.

− Pressure-induced three-dimensional ferromagnetic correlations in the giant

magnetocaloric compound Gd5Ge4. C. Magen, L. Morellon, P. A. Algarabel, M. R. Ibarra.

− Superconducting properties of metal/MgB2 composite wires.

E. Martínez, L. A. Angurel, A. Millán, R. Navarro.

− Photo-induced chirality on achiral side chain liquid crystalline polymethacrylates L. Oriol, M. Piñol, R. M. Tejedor, J. L. Serrano, R. Alcalá, F. J. Rodríguez, B. Villacampa

− Chiral helical induction through H-bonding in supramoelcular polymers.

J. Barberá, L. Puig, J. L. Serrano, T. Sierra.

− Novel NLO-phores with proaromatic donor and acceptor groups. R. Andreu, J. Garín, J. Orduna, R. Alcalá, B. Villacampa.

− The cryogenic current comparator, design tools for an ultimate precision

instrument. J. Sesé, A. Camón, C. Rillo.

39

OBSERVATION OF DISCRETE BREATHERS IN JOSEPHSON ARRAYS

J. J. Mazo

Under the exotic name of discrete breathers

or intrinsic localized modes we refer to the dynamical phenomenon of energy localization by nonlinearity and discreteness in perfect -disorder free- lattices. Our group at ICMA has been pioneering in the theoretical study of such modes. We have also carried out the theoretical prediction and experimental detection of discrete breathers in Josephson arrays, a type of superconducting solid-state devices. This work is one of the first and, to our opinion, one of the clearest observations of discrete breathers in any real system.

Before the discovering of discrete breathers,

the phenomenon of energy localization in physical lattices was associated with the existence of defects or disorder in the lattice. It was thought that any initially localized state would radiate energy and delocalize emitting plane waves or phonons, the linear vibrational modes of the lattice. However, an intense theoretical and computational work starting in the late 1980s showed the existence of long-living localized modes in discrete and non-linear lattices without disorder. Such modes correspond to – usually periodic – localized vibrations or rotations in the lattices. Intrinsic localized modes exist both for the case of Hamiltonian lattices (energy is conserved) or dissipative and biased ones (where external bias balances the losses due to the intrinsic dissipation). It is also important to say that, contrary to other nonlinear excitations, discrete breathers exist in one-, two- or three-dimensional systems 1.

Figure 1 shows a numerical simulation of a

localized vibrational mode in a Frenkel-Kontorova chain. This system is formed by a chain of nonlinear pendula joined by harmonic springs and subjected to dissipation and a periodic external force; see the small amplitude oscillation of particles in the ends. As it can be seen, the breather solution corresponds to a highly localized vibration of the chain. The particles in the core of the breather describe large amplitude oscillations meanwhile other particles librate with small amplitude under the effect of the external force. From the point of view of the theory of dynamical systems, the solution is an attracting limit cycle, and it is structurally stable and robust under thermal fluctuations.

Figure 1 shows an example of a mode with

localized oscillation or oscillobreather. However, for the case of arrays made of interacting rotors it is possible to have also localized rotations or rotobreathers.

2550

75100

960

970

980

990

1000

Figure 1: One discrete breather (oscillobreather) After some years of intense theoretical and numerical work; recently, most of the efforts in this field have been focused on the experimental detection of discrete breathers in real physical systems. In fact, up to the date they have been observed in solid state mixed-valence transition metal complexes, quasi-1D antiferromagnetic chains, superconducting arrays made of Josephson-junctions, micromechanical oscillators, optical waveguide systems and 2D photonic structures 1.

Our team of the department of Theory and Simulation of Complex Systems at ICMA has played a key role in the achievement of the experimental observation of discrete breathers in Josephson arrays.

In the work of 1996 2 it was proposed a particular Josephson-junction configuration, the ladder as an ideal experimental system to study the phenomenon of intrinsic localization. There, and in following works, the theoretical basis was established and the existence of discrete breathers in such arrays predicted. Based on such theoretical studies, the experimental effort to excite and detect localized solutions was carried out independently by the group of Terry Orlando at MIT 3 -in close collaboration with the author, Visiting Scholar at MIT at the time-, and the group of Alexey Ustinov in Erlangen 4 -also linked to our group through a common European project-. The experiments were successfully carried out in both laboratories. A nice brief presentation of both works can be found in 5 and a longer, still popularized one in 6. For more authorized reviews, see P2 and 7.

Figure 2 shows one of the superconducting Josephson ladders fabricated to observe rotobreather states. The junctions are made by Niobium superconducting islands connected by thin Aluminium Oxide insulating barriers. The ladder consists on two rows with 9 Niobium islands each one, connected through a total of 25 Josephson-junctions: 9 vertical and 16 horizontal (8 in the top row and 8 in the bottom one).

40

Figure 2: The Josephson ladder (Josephson junctions are sketched in red at the bottom right panel)

Each junction in the ladder can be modelled

by a nonlinear rotor characterized by a phase, an angular variable. The localized state we are looking for is a rotobreathers: a few of the junctions are in a resistive state (which corresponds to a rotation of the phase) and the others in a superconducting one (these phases do not rotate). Figure 3 illustrates some of the many different breather states that were observed in Josephson ladders. There, crosses have been used to denote resistive (rotating) junctions and shorts for superconducting ones. Some of them are up-down symmetric, others not; some correspond to one-site solutions, others to m-site ones. Figure 4 shows one of the current-voltage curves measured in the ladder that allowed detecting the discrete breather solutions.

single-site

multi-site

multi-breathers

single-site

multi-site

multi-breathers

Figure 3: Zoo of breather excitations

0,0

0,5

1,0

1,5

2,0

2,5

3,0

-1 0 1 2 3

Breather state

V4 , V5, V6V4T , V6T

V4 , V5Multi-sitebreather states

Zero voltage state

Resistive branch

V4 , V5 , V6

T = 5.2 K

InitialcurrentV4 , V6

V5

V5T

V4T

V4 , V5 , V6 , V4T , V5T

Tot

al a

pplie

d cu

rren

t (m

A)

Junction Voltage (mV)

Figure 4: The experimental detection After observation in the ladder, the new

challenge of the field is the experimental detection of a discrete breather in a two-dimensional array. Recently, we have numerically found the existence of such states, see figure 5 for a simulation, and established the experimental conditions for the excitation and detection of discrete breathers in a two-dimensional array P1. Recent experiments, not yet published, performed by Ustinov’s group valid this scenario.

Figure 5: Rotobreather in a 2D Josephson array

Principal publication P1 J. J. Mazo. Phys. Rev. Lett. 2002, 89, 234101. P2 J. J. Mazo, T. P. Orlando. Chaos 2003, 13, 733.

Acknowledgements Financial support by DGES (PB98-1592), EU (HPRN-CT-1999-00163) and MCyT (BFM2002-00113). References 1 D. K. Campbell et al, Physics Today 2004, 57, 43. 2 L. M. Floría, J. L. Marín, P. J. Martínez, F. Falo, S. Aubry. Europhys. Lett. 1996, 36, 539. 3 E. Trías, J. J. Mazo, T. P. Orlando. Phys. Rev. Lett. 2000, 84, 741. 4 P. Binder et al. Phys. Rev. Lett. 2000, 84, 745. 5 L. M. Floría. Physics World 2000, 13 (4), 23. 6 L. M. Floría, J. L. Marín, J. J. Mazo. Investigación y Ciencia, Junio 2002. 7 J. J. Mazo in “Energy localization and transfer”. Advances Series in Nonlinear Dynamics, World Scientific, 2004, vol 22. 193.

41

LUSTRE POTTERY: THE SECRET OF EARLY NANOMATERIALS REVEALED BY TRANSMISSION ELECTRON MICROSCOPY

A. Larrea, J. Pérez-Arantegui

Lustre is a type of ceramic decoration, which results in a beautiful metallic shine and coloured iridescence on the surface of the ceramic object. Among the different ceramic techniques often termed as ‘lustre’, the ‘reduced-pigment lustre’ is made by applying some pigments (usually silver and copper compounds) mixed with clay or ochre to the surface of an already-fired glaze. Then the ceramic piece is re-fired to a low temperature in a reducing atmosphere. When the piece is cool and out the kiln, the surface is cleaned by rubbing to remove the clay that is on the design, and lustre appears with metallic sheen and different colours. Almost all the lustre made before 1800 belongs to this family and it includes all Islamic, Spanish and Italian lustre ware.

The earliest lustre was probably made in Iraq in the IXth century AD on tin-glazed ceramics. Lustre technology spread from the Middle East to Persia, Egypt and Spain, through Islamic cultural exchanges. In the Muslim Spain, the first examples date back to the 12th-13th c. AD, and they were followed by a very large and splendid Hispano-Moresque production during the 14th and 15th centuries in the area of Valencia and continued in the following centuries (Figure 1). From Spain, lustre pottery was introduced in the Italian peninsula where the famous ‘majolica’ was decorated by this technique since the 15th and 16th centuries.

Figure 1: Lustre ceramic from Manises, circa XVth century. Courtesy of Museu de Ceràmica, Barcelona, Spain.

Therefore, lustre pottery has been known for more than a thousand years but it has always been perceived as enigmatic. This special consideration becomes from the secrecy of its

very difficult production technology, kept zealously during centuries by the potters: “many make them (the lustre pottery) on the floors of houses which are locked and under close guard, for they look on the manner of making the kiln as an important secret and say that in this consists the whole art” (Piccolpasso, 1557) 1. Although an important amount of information is now available, the theory of this technology is not completely understood and the practice remains uncertain because of the number of variables.

The production of lustre was seldom described in detail before the late 19th century. However no written records exist for the first four centuries, therefore there is a risk of interpreting the ancient technology in terms of current techniques. This is why an extensive study of Medieval lustre pottery is carried out in order to know and to understand the pigments used, the way of production, the microstructure of the decoration and its optical behaviour and appearance 2.

The knowledge of some of the compounds used as pigments for lustre, the reducing atmosphere currently used and the resulting metallic aspect helped to suppose that lustre was caused by a metallic film created during firing on the glaze surface, but at present only a few attempts had been published to verify the chemical and structural composition of lustre. These previous studies concluded that silver and copper were the main components of lustre. But many questions about metallic and crystalline character of these components and its complete microstructure remained still unanswered. Therefore an especial analytical approach, the Transmission Electron Microscopy (TEM), was needed to resolve the composition and microstructure of lustre. In order to study the complete in-depth lustre microstructure, a cross section was preferred for observing the samples under TEM. The preparation method used for preparing the thin cross-section specimens was first developed by Abrahams and Buiocchi for studying semiconductor epitaxial structures 3.

Two different types of samples were selected for studying lustre decoration, they were chosen because they belonged to the extremes of colour range appeared on lustre pottery. The first sample (A) is a fragment decorated with red-brown copper-like lustre from Paterna (Spain), 14th century AD, and the second one (B) is part of a Syrian ceramic, 12th century AD, with a green-olive yellowish lustre. In both cases, samples belonged to ceramics decorated with lustre designs on white tin-glazes.

In TEM, sample A appeared with a homogeneous surface microstructure formed by small quasi-spherical clusters, arranged in two

42

different sizes and embedded in an amorphous matrix (the glaze) (Figure 2). The total thickness of this structure was between 200 and 500 nm. A first outer layer was formed by the biggest clusters, which had a diameter of about 50 nm. Diameter of the other smaller inner clusters was between 10 and 20 nm.

Figure 2: TEM image of a red-brown, copper-like lustre. The inset corresponds to the CBED pattern of a copper particle.

About the composition of these clusters, TEM-EDS analyses indicated that the nanoclusters were particles of pure copper. Convergent-beam electron diffraction (CBED) in 50 nm diameter particles proved that they were crystals of metallic copper; inset in Figure 2 shows the face-centred cubic arrangement pattern, with a cell parameter of 1.80 Å corresponding to metallic copper.

Sample B showed a slightly different microstructure in TEM. Also in this case a nanostructure formed by small clusters appeared in the surface of the glaze (Figure 3). Nanoclusters were embedded in the matrix covering a thickness about 1 µm. Clusters seemed to be classified in three ranges of size; the outer layer was constituted by clusters of diameter between 7 and 10 nm; these first clusters were continued by a layer of very small particles of about 4 nm of diameter and the most inner clusters were the biggest with a diameter of 15-20 nm.

TEM-EDS analyses in the nanoparticles indicated that they were composed by silver, but in this case the smaller size of particles did not allow us to avoid the presence of glaze components by means only of the micro-analytical results. In this second sample, the electron diffraction was also key in resolving the nanoparticle nature. SAD patterns (inset of figure 3) of these particles showing its diffraction rings proved that nanoparticles were crystals of metallic silver.

Figure 3: TEM image of a green-olive, yellowish lustre. The inset corresponds to the SAD pattern of silver particles.

Summarising, lustre is the first nanostructured metallic thin film made by person, as revealed by Transmission Electron Microscopy. Considering cultural heritage of this type of decoration, this is a remarkable point in the History of the Technology, because nanocrystal films were produced empirically since the medieval period and this means a high level of technological knowledge of materials science to obtain and to reproduce lustre layers.

Principal publications J. Pérez-Arantegui, A. Larrea. Trends in Analytical Chemistry 2003, 22, 327. J. Pérez-Arantegui, J. Molera, A. Larrea, T. Pradell, M. Vendrell-Saz, I. Borgia, B. G. Brunetti, F. Cariati, P. Fermo, M. Mellini, A. Sgamellotti, C. Viti. J. Am. Ceram. Soc. 2001, 84, 442. Acknowledgements This study was supported by P047-2000 research project of the CONSID-DGA (Aragonese Government), Spain. References 1 C. Piccolpasso. I Tre Libri dell’Arte del Vasaio, 1557; Edizioni all’Insegna del Giglio: Firenze, 1976. 2 J. Molera, M. Mesquida, T. Pradell, J. Pérez-Arantegui, M. Vendrell-Saz. Archaeometry 2001, 43, 455. 3 M. S. Abrahams, C. J. Buiocchi. J. Applied Physics 1974, 45, 3315.

43

CERAMICS FOR HIGH TEMPERATURE STRUCTURAL APPLICATIONS

J. I. Peña, A. Larrea, R. I. Merino, I. de Francisco, P. B. Oliete, V. M. Orera

Excellent chemical stability in oxidizing atmospheres makes ceramic oxides suitable for high temperature structural applications. However, the poor creep resistance and the presence of low melting point intergranular phases in conventional ceramics deteriorates the mechanical behaviour of conventional oxide ceramics above 1000 ºC. This limitations can be successfully eliminated in the Al2O3 based eutectic ceramics grown from melt. This is the case for the Al2O3-ZrO2(Y2O3) and Al2O3-YAG systems we have grown using laser assisted directional solidification. The systems consist of YSZ or YAG phases, in the form of rods or small platelets of micron or nanometer size dispersed into the continuous sapphire phase. Combination of the outstanding creep behaviour of Al2O3 along its c-axis, together with the huge amount of clean and strong grain boundaries characteristic of the eutectic solids results in a new set of ceramic oxides with excellent creep behaviour and a good retention of their mechanical properties up to temperatures above 1700 ºC even in corrosive environments 1-3.

Directionally-solidified eutectic rods or plates

have been produced by the laser-heated floating zone method using either CO2 or diode stack lasers 4,5. The mechanical properties tests were done at the E.T.S. de Ingenieros de Caminos in Madrid (Prof. J. Llorca group). Flexural strength was measured using a three-point bend test. The fracture toughness was determined by the notch technique and also by the indentation fracture method using a Vickers indentor.

Several strategies have been used to improve the mechanical properties of the composites. On the one side we modified the characteristic size and shape of the microstructure by changing the growth parameters 6. Additionally, we also changed the yttria content in the Al2O3-ZrO2 composites. The presence of the different ZrO2 phases, cubic, tetragonal or monoclinic, was quantified using Raman and XRD techniques 7. By far the best mechanical properties were achieved for the samples with the finest interpenetrating microstructure in both compounds (Fig. 1 and 2) and about 1 mol % Y2O3, which corresponds to the tetragonal ZrO2 phase in the Al2O3-YSZ composites.

Multiphase composites may develop

thermoelastic residual stresses due to the differences between the thermal expansion coefficients of the component phases. Residual stresses play an important role in the fracture mechanisms. We have studied these residual stresses using piezo-spectroscopic and Raman techniques 7,8. Residual stresses in the Al2O3-YAG eutectics are very small (σh = -0.1 GPa) owing to the light mismatch in thermal expansion

Figure 1: SEM micrograph of Al2O3-ZrO2(Y2O3) eutectic grown at 10 mm/h. Bright phase is c-ZrO2 and dark phase α-Al2O3. Scale bar = 20 µm.

Figure 2: SEM micrograph of transverse section of Al2O3-YAG eutectic grown at 350 mm/h. Bright phase is YAG and dark phase α-Al2O3. coefficients. On the contrary large tensile residual stresses in the sapphire phase develop in the Al2O3-ZrO2 eutectic when the yttria content is low and the zirconia is in the monoclinic phase. These large residual stresses produce microcracking and a severe deterioration of the mechanical properties of the composite. On the contrary, compression residual stresses (σh = -0.35 GPa) are established in the alumina phase when the zirconia is either in the tetragonal or cubic phase. In this case the eutectic shows an excellent mechanical behaviour.

44

In Figure 3 we plot the flexural strength measured in air in rods of about 1 mm diameter showing a fine microstructure (< 1µm) at RT and 1800 K compared with those measured for the best SiC and Si3N4 composites. Our materials are much stronger than any other ceramic composite reported up to date and their mechanical properties retention at high temperatures in air is outstanding.

The Vickers hardness is also high Hv = 16 ±

0.4 GPa in both compounds.[9] The high strength of the samples is accompanied by a high toughness. In fact, the fracture toughness measured by the notch technique in Al2O3-YSZ is 7.8 MPa.m1/2 at RT 1.

It is interesting to point out here that the

Vickers hardness, fracture toughness and residual stresses measured in directionally solidified eutectic plates at ambient temperature coincide with the values obtained in rods of the same composition and microstructure. Consequently an excellent mechanical behaviour at high temperature is anticipated. These directionally solidified eutectic surfaces can be used in wear, impact or thermal resistant coatings, thermal barrier coatings or anticorrosion barriers.

Figure 3: Flexural strength of several materials measured

by the three points technique in air at different temperatures. Black squares, Al2O3-YSZ (3 mol%) eutectic with interpenetrating microstructure. Red circles, Al2O3-YAG grown at 750 mm/h.

Summarising, using the laser assisted

directional solidification technique and optimized conditions we have prepared some eutectic composites with exceptional mechanical properties. With the experimental equipments available in our laboratory can be prepare materials in the form of thin rods of less than 2

mm diameter or solidified plates up to 500 µm thick.

Principal publication R. I. Merino, J. I. Peña, N. R. Harlan, G. F. de la Fuente, A. Larrea, J. A. Pardo, V. M. Orera, J. Y. Pastor, P. Poza, J. Llorca. “Ceramic Engineering & Science Proceedings”. Ed. by Hua-Tay Lin and Mrityunjay Singh, The American Ceramic Society, OH. 2002, vol. 23, 663. Acknowledgements The flexural strength and fracture measurements have been done by J. Y. Pastor and J. Llorca in the Universidad Politécnica de Madrid. We acknowledge finantial support from the Spanish Ministry of Science and Technology through projects MAT2000-1533-C03-02 and MAT2000-1495. References 1 J. Y. Pastor, P. Poza, J. Llorca, J. I. Peña, R. I. Merino, V. M. Orera. Mater. Sci. Eng, 2001, A308, 241. 2 A. Sayir, S. C. Farmer. Acta mater. 2000, 48, 4691. 3 N. Bahlawane, T. Watanabe, Y. Waku, A. Mitani, N. Nakagawa. J. Am. Ceram. Soc. 2000, 83, 3077. 4 J. I. Peña, R. I. Merino, G. F. de la Fuente, V. M. Orera. Adv. Mater. 1996, 8, 909. 5 A. Larrea, G. F. de la Fuente, R. I. Merino, V. M. Orera. J. Eur. Ceram. Soc. 2002, 22, 191. 6 J. I. Peña, R. I. Merino, N. R. Harlan, A. Larrea, G. F. de la Fuente, V. M. Orera. J. Eur. Ceram. Soc. 2002, 22, 2595. 7 N. R. Harlan, R. I. Merino, J. I. Peña, A. Larrea, V. M. Orera, C. González, P. Poza, J. Llorca. J. Am. Ceram. Soc. 2002, 85, 2025. 8 V. M. Orera, R. Cemborain, R. I. Merino, J. I. Peña, A. Larrea. Acta mater. 2002, 50, 4677. 9 A. Larrea, V. M. Orera, R. I. Merino, J. I. Peña. J. Eur. Ceram. Soc. (in the press).

45

HYSCORE SPECTROSCOPY OF THE CYTOCHROME b559 OF PHOTOSYSTEM II

REACTION CENTRE

P. J. Alonso, J. I. Martínez

Cytochromes are electron transfer heme proteins that are involved in many biochemical processes and exhibit a large variety of redox potential. These characteristics allow them to act as electron carriers in different metabolic reactions and other processes in living organisms. The relationship between the electronic structure of the heme group (the final acceptor of the first donor in the redox reaction of cytochromes) and the reaction mechanism is not well understood in most cases.

As the ferric state of the cytochromes is paramagnetic, Electron Paramagnetic Reso-nance (EPR) techniques have been used to characterize this kind of proteins 1. Continuous wave (cw-EPR) spectroscopy gives useful information about the unpaired electronic distribution in the heme centers 1. Nevertheless, no information about the hyperfine and quadrupolar interactions with the neighboring nuclei can be obtained with this conventional technique because of its lack of resolution. With the aim of overcome this limitation ENDOR and, more scarcely, electron spin echo modulation (ESEEM) techniques have been applied to study different heminic systems, both in hemeproteins and heme model systems 2-3.

It has to be taken into account that in hemoproteins the Fe3+ paramagnetic entity is surrounded by many magnetic nuclei (five or six nitrogen and several protons) interacting with the unpaired electron. Selective isotopic substitution would lead to a direct assignment of the signal to particular nuclei but in the practice this is not always achievable when working with biological materials. In this case the use of model systems can be helpful. Moreover, protein samples are orientationally disordered systems in most cases. Thus, the corresponding ENDOR as well as one-dimensional (1D) ESEEM spectra strongly overlap and thus are difficult to disentangle.

On the other hand, the two-dimensional (2D) ESEEM HYSCORE spectroscopy introduced some years ago has proved to be useful to study weak hyperfine interaction with many nuclei in orientationally disordered systems 4. Nonetheless, this potential has not yet been exploited to study heme systems.

We have examine the ferric state of cytochrome (Cyt) b559 from spinach by means of the HYSCORE technique. Cyt b559 is an hemeprotein constituent of the photosystem II (PSII) reaction center (RC), which is bound to the D1 and D2 polypeptides of the PSII RC. We have studied Cyt b559 in D1-D2-Cyt b559 reaction center complexes, which are the minimum PSII complexes that are able to perform efficient light induced primary charge separation. This hemeprotein consists of two small polypeptides,

the α and β subunits. Two histidine residues placed axially respect to the phorphyrin ring with the hydrophobic domain of each polypeptide act as ligands of the heme iron.

Cyt b559 was characterized by cw-EPR spectroscopy a few years ago 5. Its spectra are typical of a low spin heme iron and can be described with an fictitious spin S = ½ and an orthorrombic g-tensor with the following principal values: gx ≈ 1.5, gy ≈ 2.3, gz ≈ 3.0. Slight modifications of the gz-value depending on the preparation and purification have been described. More recent studies relate these minor modifications in the cw-EPR spectra with changes between different redox forms of Cyt b559 5. More recent studies performed in our laboratory point out that the conditions of the detergent used to stabilize the PSII RC sample is the driving force that induces the observed changes in the cw-EPR spectra 6.

With those antecedents a HYSCORE study of Cyt b559 was undertaken. In this case, it is not possible to work with selectively labeled Cyt b559. Thus we have also studied heme model compounds that have similar cw-EPR and HYSCORE spectra. In these model compounds two imidazol axial ligands mimic the histidine residues. By selective isotopic substitution of iron bond nitrogen atoms in these simpler systems a direct assignment of the HYSCORE signals was done. Because of the similarity of the spectra this assignment can be extended to the Cyt b559.

The high anisotropy of the cw-EPR spectra allows making orientation selection HYSCORE spectra. Different spectra for magnetic field values corresponding to the principal values of the g-tensor were measured.

ν2 (MHz)

ν 1(M

Hz)

-15 -10 -5 0 5 10 15

24

68

1012

14

N-HemN-Im

ν2 (MHz)

ν 1(M

Hz)

-15 -10 -5 0 5 10 15

24

68

1012

14

N-HemN-Im

Figura 1: HYSCORE spectrum of a 14N natural abundance model compound measured at 10 K with an static magnetic field of 234 mT (gz-spectrum) the separation between the two fisrt pulse was τ = 96 ns. The dq-dq correlation due to N-Im and N-Hem are indicated.

As an example, the HYSCORE spectrum

measured with a magnetic field corresponding to gz (234 mT) in the model compound with a natural content of 14N is given is figure 1. By

46

comparison with the HYSCORE spectra of 15N selectively labeled in the porphyrin ring, in the imidazol moiety or in both, the assignation of the observed signal to each type of nitrogen atoms was done

The HYSCORE spectra allow obtaining the corresponding nuclear splitting of both types of nitrogen atoms and then, the principal values of the hyperfine and quadrupolar coupling tensor and the orientation of their principal axes respect to the g-tensor.

As all the heme nitrogen atoms are equivalent in the gz spectra it is followed that the z-principal axis of the g-tensor is normal to the heme plane. Consequently, the orientation of the g-tensor principal axes respect to the molecule is determine by the angle, Θ, that the X-axis makes with a Fe-N-Hem bond direction. From the quadrupolar tensor of the N-Hem atoms is estimated that 20° < Θ < 38°. This is illustrated in figure 2.a where the orientation of the g-tensor X-principal axis in the porphyrine plane is indicated

X

N

NN

NFe

a)

N

FeNN

N

x´

yÍMIDAZOL

PLANE

b)

X

N

NN

NFe

a)

X

N

NN

NFe

a)

N

FeNN

N

x´

yÍMIDAZOL

PLANE

b)

N

FeNN

N

x´

yÍMIDAZOL

PLANE

b)

Figura 2: (a) Orientation of the g-tensor X-principal axis in the porphyrine plane; dashed lines indicate a range for possible orientation and the continuous arrowed line shows the mean orientation. (b) The thick line indicates the orientation of the imidazol plane; the range of possible oreintations is in between the dashed lines.

From the analysis of the quadrupolar tensor

for N-Im atoms the orientation of the imidazol plane is obtained. It is depicted in figure 2.b. Furthermore the g-tensor principal values strongly suggest that both imidazol plane are parallel.

An analysis of the g-tensor using the Taylor´s model 1 indicates that the unpaired electron density is mainly in a dy´z like-orbital which is normal to the heme ring and to the imidazol plane. It is also illustrated in figure 2.b.

As far as the hyperfine interaction with the nitrogen atoms is concerned the obtained results indicate that this interaction is mainly isotropic and the unpaired electronic orbital have a strong non-bonding character.

The strong similarity between the spectra of the model compound and Cyt b559 lead to extent these conclusions to the cytochrome. In particular the structure of the heminic center in

this protein should be the same as the one depicted in figure 2. It is worth of noting that in spite of the observed principal g-values modification no differences are found in the interaction parameters when detergent conditions used to stabilize Cyt b559 samples change.

As it has been commented above, the hyperfine data indicate that the unpaired electron is localized in confined iron orbital with a negligible mixture of p-orbitals. This makes very unlikely that any substrate or reactive can be located close enough to the orbital occupied by the exchangeable electron for a direct one-step electron exchange. The transfer mechanism could be better understood if it were a multistage complex process where the metal in the heme group acts as a final electron reservoir. So, the g-tensor principal values would mainly depend on the metal electronic structure and near environment whereas measured redox potential would rather be related with the accessibility of mediators and the actual reaction process in the experiment. Such processes will depend in a complex way on the whole protein conformation. That would explain that there is not a direct relationship between the cw-EPR signal and redox potential as it was assumed before 5.

Finally we want to point out that this assertion could be considered as a more general conclusion being extended to other cytochromes. Anyway, this work proves the strong potentiality of the HYSCORE spectroscopy to obtain relevant information about the structure and function of metalloproteins.

Principal publication I. García-Rubio, J. I. Martínez, R. Picorel, I. Yruela, P.J. Alonso. J. Am. Chem. Soc. 2003, 125, 15846.

Acknowledgements This work was supported by the CONSI+D (DGA, local government of Aragón) under contract P111/2001. References 1 C. P. S. Taylor. Biochem. Biophys. Acta 1977, 491, 137. 2 N. D. Chasteen, P. A. Snetsinger. In Physical Methods in Bioinorganic Chemistry. Spectroscopy and Magnetism. L. Que Editor University Science Books. Sausalito (CA, USA) 2000. ch 4. 3 F. A. Walker. Inorg. Chem. 2003, 42, 4526. 4 J. J. Shane, P. Höfer, E. J. Reijerse, E. de Boer. J. Magn. Reson. 1992, 99, 596. 5 D. M. Stewart, G. w. Brudvig. Biochem. Biophys. Acta 1998, 1367, 63. 6 I. Yruela, I. García-Rubio, M. Roncel, J. I. Martínez, V. M. Ramiro, J. M. Ortega, P. J. Alonso, R. Picorel. Photochem. Photobiol. Sci. 2003, 2, 437.

47

ENHANCED ANISOTROPY OF NANOSIZED CoCLUSTERS: EFFECTS FROM SURFACE

AND INTER-PARTICLE INTERACTIONS

F. Luis, J. M. Torres, L. M. García, J. Stankiewicz, J. Bartolomé, F. Petroff Clusters of magnetic materials, like Fe, Co, and Ni, have technological interest for application in future high-density information storage devices. In addition, they enable us to investigate how the magnetic properties evolve as the material’s size changes from the macroscopic towards the atomic limits.

Figure 1. Transmission electron microscopy (TEM) of a cross section of a multilayer showing the quasi-ordered arrangement of Co nanospheres (black dots). The magnetic anisotropy of nanometer-sized metallic clusters determines the stability of their magnetic moments against thermal fluctuations. Therefore, this magnitude plays a crucial role for applications, since, in fact, it limits the minimum size that a particle must have to store information. The continuous interest in increasing the density of recording media has motivated a very intense research activity devoted towards understanding the physical origin of the magnetic anisotropy and finding new methods to enhance it 1. In our work, we have experimentally studied how the activation energy U that is required to flip the magnetic moment of a Co nanosphere depends on its size and on the interaction with neighboring clusters in dense arrays. Clusters containing between 25 and 4000 Co atoms are formed by aggregation of Co atoms deposited by rf sputtering on a flat alumina (Al2O3) surface. The average size of the clusters can be controlled by increasing the net amount of Co deposited per layer. The clusters are nearly spherical and show the atomic packing characteristic of the fcc crystallographic phase. They are protected against subsequent oxidation by a layer of alumina. Multilayers prepared by piling up a number of these Co/Al2O3 bilayers show a quasi-ordered spatial arrangangement

that, for nearest neighbors, resembles that of a hexagonal close-packed structure (see Fig. 1) 2. The effective activation energy U for clusters of average diameter ⟨D⟩ has been estimated from a scaling analysis 3 of the out-of-phase component of the ac magnetic susceptibility. From this value, we estimate the effective anisotropy Keff = U/V, where V = (π/6)⟨D⟩3 is the average particle’s volume. Our results, shown in Fig. 2, show that Keff of Co nanospheres is larger than the anisotropy constant of bulk fcc Co and that it strongly depends on the cluster’s size.

Figure 2. Size dependence of the effective anisotropy of Co nanospheres. The solid (red) line is a least squares fit to equation Keff = Kbulk + Ks/D, where Kbulk is the anisotropy of bulk fcc Co (horizontal line) and Ks = 0.33 mJ/m2 is the surface anisotropy constant. The observed enhancement is approximately proportional to the fraction of atoms located at the surface of the clusters. We associate this effect with the low symmetry of the surface atomic sites that might lead to a reduced quenching of the orbital magnetic moments, thus also increasing the spin-orbit interaction energy that is at the origin of the magnetic anisotropy 4. The strong pinning of the surface spins therefore dominates the magnetization switching time for the whole cluster. For applications, it is also crucial to know how magnetic dipolar interactions modify the superparamagnetic relaxation rate. The importance of this effect is evident in high density recording media. Unfortunately, experiments performed until now give different and even contradictory results 5,6. It is usually very complicated to disentangle the influence of the dipole-dipole interactions from other effects, such as size-dependent anisotropy, cluster

Bulk fcc

48

aggregation, direct exchange interactions, etc. Theoretical models are also not free from contradictions, predicting that the reversal of magnetic moments becomes either faster or slower as the dipolar interactions are switched on. In order to solve this long debated and complicated puzzle, experiments performed on simple systems are therefore highly desirable. By varying the number N of layers while keeping the average cluster’s size constant, we have been able to study how the dipolar interactions between the clusters modify the average activation energy. As Figure 3 shows, the blocking temperature TB increases very rapidly for N ≤ 5 and then it saturates to a nearly constant value. By contrast, experiments performed on a multilayer with N = 20 but larger separation between layers show exactly the same TB value as that of a single layer.

Figure 3. a) Variation of the blocking temperature with the number of layers; dots, separation between adjacent layers 3 nm; triangles, separation between layers 10 nm. b) Dots, same data as in a) plotted as a function of the average number of nearest neighbor clusters located in adjcent layers; crosses, average activation energy estimated as the slope of the Arrhenius law frequency-dependence of the ac susceptibility blocking temperatures. These results neatly show that the magnetization switching becomes slower with increasing the interactions’ strength. In addition, the rapid saturation as a function of N suggests that the main contribution comes from the interaction with the first shell of neighbors. Indeed, if we plot the same data as a function of the average number N⊥ of neighbors that a cluster has in the two nearest layers, we find that both TB and U are simply proportional to it (Fig 3, panel b). For the first time, profitting from the very high quality of the samples, we have been able to directly compare the experimental results to theoretical predictions with almost no free parameters. The calculated results (solid lines in Fig. 3) account very well for the observed increase of TB and for the dominant role of nearest neighbors. Our results can be summarized in a very simple expression, which relates the activation energy of small clusters to their size and to the number Nnn of nearest neighbor spins, as follows

U = KsS + A Nnn where Ks is a surface anisotropy constant, S = π2D is the surface area of the nanosphere and A is a parameter that depends on the spatial arrangement of clusters in the array. The crucial role played by the atoms located at the cluster’s surface might be employed to modify, read enhance, the magnetic anisotropy by simply changing the properties of the interface with the embedding matrix. In addition, our study shows that interparticle intreractions estabilizes the particle’s magnetization in zero magnetic field. By contrast, the switching speed of the magnetic moment by an external field, as when a bit is stored, is nearly unaffected by interactions. Principal publications F. Luis, J. M. Torres, L. M. García, J. Bartolomé, J. Stankiewicz, F. Petroff, F. Fettar, J. L. Maurice, A. Vaurès. Phys. Rev. B 2002, 65, 094409 F. Luis, F. Petroff, L. M. García, J. Bartolomé, J. Carrey, A. Vaurès. Phys. Rev. Lett. 2002, 88, 217205; ibid 2003, 90, 059706 Acknowledgements This research has been partly funded by Spanish (grant MAT 99/1142) and the European ESPRIT (contract MASSDOTS). References 1 R. L. White. J. Mag. Mag. Mater. 2000, 209, 1; D. Weller, A. Moser. IEEE Trans. Mag. 1999, 35, 4423. 2 D. Babonneau, F. Petroff, J. L. Maurice, F. Fettar, A. Vaurès. Appl. Phys. Lett. 2000, 76, 2892. 3 M. I. Shliomis, V. I. Stepanov. Adv. Chem. Phys.1994, 87, 1; F. Luis, J. Bartolomé, J. Tejada, E. Martínez. J. Mag. Mag. Mater. 1996, 157-158, 266. 4 P. Bruno. Phys. Rev. B 1989, 39, R865. 5 J. L. Dormann, L. Bessais, D. Fiorani. J. Phys. C 1988, 21, 2015; W. Luo, S. R. Nagel, T. F. Rosenbaum, R. E. Rosensweig. Phys. Rev. Lett. 1991, 67, 2721; J. L. Dormann, F. D'Orazio, F. Lucari, E. Tronc, P. Prenté, J. Jolivet, D. Fiorani, R. Cherkaoui, M. Noguès. Phys. Rev. B 1996, 53, 14291. 6 S. Mörup, E. Tronc. Phys. Rev. Lett. 1994, 72, 3278; S. Mörup, F. Bödker, P. V. Hendriksen, S. Linderoth. Phys. Rev. B 1995, 52, 287.

49

A THIAZYL-BASED ORGANIC FERROMAGNET: MAGNETISM AND SPIN-DENSITY

DISTRIBUTION BY POLARISED NEUTRON. DRIFFRACTION EXPERIMENTS AND AB INITIO CALCULATIONS

J. Campo, F. Palacio, J. Luzón, G. J. McIntyre, A. Alberola, J. M. Rawson, C. Paulsen, R. D.

Farley

In 1928 Heisenberg proposed 1 that bulk ferromagnetic order would only ever be achieved in systems containing heavy atoms, i.e. metals, their oxides and related derivatives. Indeed it was not until 1991 that the first organic ferromagnet was reported; the β-polymorph of the radical p-NPNN was shown to order below 0.6K 2. Since then a number of other organic radicals have been found to undergo bulk ferromagnetic order, although they almost invariably order below 1K. The nitroxide-based diradical DOTMDAA is the sole exception, ordering at 1.6K 3. We have previously shown that the thiazyl radical p-NCC6F4CNSSN• orders as a canted antiferromagnet at 36K under ambient pressure 4, the highest reported magnetic ordering temperature for an organic radical. By replacing the CN group by Br a paramagnetic system possessing very weak antiferromagnetic interactions is obtained 5. We have recently reported that if the CN group is substituted by NO2 to give the p-O2N·C6F4CNSSN• radical, ferromagnetic ordering is observed below Tc = 1.3 K 6. This is the first S-based organic radical, entirely metal-free, to undergo ferromagnetic ordering and only the second organic radical to order as a ferromagnet above 1K.

These different magnetic behaviors are due to the change in the molecular packing (see Fig. 1 for the p-O2N·C6F4CNSSN•, and consequently a substantial modification of the magnetic interaction pathways. Knowledge of the spin-density distribution in the dithiadiazolyl radical ring allows us a better understanding of the rich magnetism of DTDA derivatives and hence helps in the design of new organic ferromagnets based on the DTDA ring with higher TC.

Figure 1. Crystal structure of p-NO2.C6F4CNSSN•

Here we report on the magnetism of the p-

O2N·C6F4CNSSN• radical and on the study of its spin-density distribution using polarized-neutron diffraction and ab initio calculations techniques.

Low temperature ac susceptibility measurements on a single crystal of p-O2N·C6F4CNSSN• were made between 0.6 and 2.5K on a SQUID magnetometer in a field of 2G. The crystal, when oriented both perpendicular and parallel to the [001] axis, showed an abrupt increase in the out-of-phase susceptibility below 1.4 K, reaching a maximum at 1.3K, consistent with the onset of bulk ferromagnetic order at Tc = 1.32±0.02K [Fig. 2]. Little anisotropy in M vs H or χ vs T data was observed. The difference in the data is attributed to demagnetising effects arising from the sample geometry.

0

5

10

15

20

25

30

35

0 1 2 3 4 5 6

[001] axis(001) axis

χ' (e

mu/

mol

)

T (K)

Figure 2. Single-crystal ac susceptibility of the p- O2N·C6F4CNSSN• radical in an applied field of 2 G and at 1.11 Hz.

The polarized-neutron diffraction experiment was performed on the D3 lifting-counter diffractometer at the ILL at 1.5 K in an applied field of 9 T. A multipolar model of the spin density (Fig.3) was fitted to the measured flipping ratios. Almost all the spin density is localized in the nitrogen and sulfur p orbitals perpendicular to the DTDA ring (0.281µB and 0.247µB, respectively). These orbitals generate the Single Occupied Molecular Orbital (SOMO). Some negative density is observed between the sulfur and nitrogen atoms that can be due to covalence and polarization effects. In addition, a

50

small negative density is observed (-0.055µB) on the carbon site of the DTDA ring due to polarization effects. The spin density over the rest of the radical is below the limits of the experimental accuracy 7.

Figure 3. Spin-density reconstruction of the p-O2N·C6F4CNSSN• radical projected along the perpendicular to the CNSSN mean plane.

To support the experimental modeling, ab

initio calculations were performed at the generalized gradient approximation level, using several exchange-correlation functionals (PW91, BLYP,VWM) with a double numerical basis set including functions and numerical integrations, as implemented in the Dmol3 software based on density functional theory. Both periodic (crystal) and molecular calculations were made.

The ab initio calculations (Fig 4 and Table I) confirm the experimental results and, in particular, they show that the negative spin density in the plane of the DTDA ring is not a spurious effect of the multipolar model used. Such a negative spin density plays an important role in the ferromagnetic behavior of the O2N·C6F4CNSSN• radical. The spin populations in the rest of the molecule were also obtained. In the carbon atoms negative and positive low spin density populations alternate due to polarization effects. Only a weak indication of the latter was observed experimentally, which emphasizes the importance of combining experiment and ab initio calculations in this kind of studies.

Table I. Ab initio and experimental spin-density populations in the p-O2N·C6F4CNSSN• radical

µB BLYP molec.

PW91 molec.

VWM molec.

BLYP crystal

This experim.

N2 0.226 0.220 0.225 0.214 0.247

S1 0.308 0.312 0.310 0.317 0.281

C5 0.065 -0.061 -0.062 -0.061 -0.055

C1 -0.003 -0.003 -0.003 -0.003

C2 0.001 0.001 0.001 0.002

C3 -0.004 -0.004 -0.004 -0.004

C4 0.005 0.002 0.002 0.004

F2 0.000 0.000 0.000 0.001

Figure 4. Spin density distribution of the p-O2N·C6F4CNSSN• radical calculated with the Dmol3 package (BLYP functional, molecular calculation). The red surface is the contour of 0.0002 µB/Å3 and the blue one is the contour of –0.0002 µB/Å3. Principal publication A. Alberola, R. J. Less, C. M. Pask, J. M. Rawson, F. Palacio, P. Oliete, C. Paulsen, A. Yamaguchi, R. D. Farley. Angew. Chem. Int. Ed. 2003, 42, 4782. J. Luzón, J. Campo, F. Palacio, G. J. McIntyre, A. E. Goeta, C. M. Pask, J. M. Rawson. Polyhedron 2003, 22, 2301. Acknowledgements We would like to thank the E.P.S.R.C., the C.I.C.Y.T. (grant MAT2001-3507-C02-02) for financial support, and the European Science Foundation programme “Molecular Magnets” for partial support to the collaborative activities. One of us, JL, thanks the ILL for a PhD research fellowship. References 1 W. Heisenberg. Z. Phys. 1928, 49, 619. 2 H. Tamura. Chem. Phys. Lett. 1991, 186, 401. 3 R. Chiarelli, M. A. Novak, A. Rassat, J. L. Tholance. Nature 1993, 363, 147. 4 F. Palacio, G. Antorrena, M. Castro, R. Burriel, J. M. Rawson, J. N. B. Smith, N. Bricklebank, J. Novoa, C. Ritter. Phys. Rev. Lett. 1997, 79, 2336. 5 G. Antorrena, J. E. Davies, M. Hartley, F. Palacio, J. M. Rawson, J. N. B. Smith, A. Steiner. J. Chem. Soc., Chem. Commun. 1999, 1393. 6 A. Alberola, R. J. Less, C. M. Pask, J. M. Rawson, F. Palacio, P. Oliete, C. Paulsen, A. Yamaguchi, R. D. Farley. Angew. Chem. Int. Ed. 2003, 42, 4782. 7 J. Luzón, J. Campo, F. Palacio, G. J. McIntyre, A. E. Goeta, C. M. Pask, J. M. Rawson. Polyhedron 2003, 22, 2301.

51

TOWARDS THE MAGNETIC REFRIGERATION: THE MAGNETOCALORIC EFFECT.

A NEW METHOD OF CHARACTERIZATION WITH AN ADIABATIC SYSTEM

R. Burriel, E. Palacios, L. Tocado

The Kyoto protocol establishes a gradual

reduction of gas emissions to control the greenhouse effect and the destruction of the ozone layer. The conventional refrigeration systems are based on the cyclic compression and expansion of some fluid with the subsequent gas-liquid transitions. The heat transferred from the cool source to the hot one is basically the latent heat of vaporization. The typical fluids used for this purpose are highly contaminant in the sense of the Kyoto protocol. They are confined to closed circuits, but sooner or later they leak to the atmosphere. Therefore some alternatives are being searched. One of the most promising methods is based on the magnetocaloric effect (MCE). The exchange fluid does not need to have a phase transition and can be an innocuous liquid like just water or a solution of water - alcohol.

The MCE is the heating or cooling of a sample when a magnetic field H is applied or removed. The reduction of magnetic entropy provoked by the field implies an increase of lattice vibrations in an adiabatic process and, consequently, a raise of temperature. It is tied to the alignment of the magnetic moments, decreasing the number of thermally accessible Zeeman states, which is 2J+1 for H = 0, being J the quantum angular momentum for the magnetic atom. The inverse process, known as adiabatic demagnetization, consists on removing the magnetic field acting on a paramagnetic salt, which has been precooled in an external field down to liquid helium temperatures or lower.

At higher temperatures, the alignment of the spins needs more and more intense fields to compensate for the thermal excitations. This problem can be solved by choosing a ferromagnetic substance near the Curie point TC, where the susceptibility increases sharply.

Figure 1 shows the typical temperature dependence of the entropy for a ferromagnetic material near TC at zero field and in an applied

field H. One of the most efficient processes working continuously is the Ericsson cycle, ABCDA, formed by two isothermal and two isofield lines. The most relevant quantities describing the main features of the material as a refrigerant are the isothermal entropy change ∆ST and the adiabatic temperature increment ∆TS when a field H is applied. A suitable substance for magnetic refrigeration should have the highest possible values of these magnitudes in the range of the working temperatures.

The characterization of a given material can be done with magnetization and field dependent heat capacity measurements (Cp,H). The entropy can be obtained from the integrals

∫ ⎟⎠⎞

⎜⎝⎛

∂∂

=∆H

HpT dH

THTMS

0 ,

),( or

( )∫=T

Hp dTT

TCHTS

0

,),(

then, ∆ST = S(T,0) - S(T,H) and [ ]SHS STSTT 0)()( −=∆ being T(S)H the inverse function of S(T,H) for a constant H.

The easiest experimental measurement is the magnetization, but this method allows having only ∆ST and not ∆TS, for which one would need the heat capacity at every field

∫ ⎟⎠

⎞⎜⎝

⎛∂

∂−=∆

H

HpHpS dH

THTM

CTT

0 ,,

),(

Moreover, the first integral is based on the

Maxwell relation TH H

STM

⎟⎠

⎞⎜⎝

⎛∂∂

=⎟⎠

⎞⎜⎝

⎛∂∂ that is not

valid in a first-order transition. These constrains make doubtful the results based on magnetization data. Therefore, the heat capacity is the main experimental characterization technique of MCE materials. In any case, near first-order transitions even the heat capacity is not as precise as in other conditions, because the relaxation time becomes very large. Another drawback of the Cp method is that it requires measurements virtually from 0 K for each field in order to avoid cumulative errors in the entropy integrals which arise when Cp,H is different from Cp,0 at low temperatures, far from the interesting range.

An alternative possibility is a direct measurement of ∆TS. In combination with heat capacity at zero field it allows to determine the isofield curves in an S/T diagram because T(S)H = T(S)H=0 + ∆TS, and T(S)H=0 is obtained from Cp,0 data. The usual experimental procedure is to apply a pulsed field or to plunge the sample into a strong static field. The procedure takes few

52

seconds so that the heat gain or loss of the sample can be neglected. This method has the experimental problem of lack of adiabaticity and the dissipated heat by induced currents for a conducting sample in a fast variable field. Dan’kov et al. 1 have estimated the accuracy to be not better than 8 % in ∆TS with this method.

We have developed a new method 2 based on a modified adiabatic calorimeter primarily designed to measure heat capacity by the heat pulse method. For the measurement of ∆TS the sample is maintained in adiabatic conditions while a field is applied quasi-statically. The process takes several minutes. Figure 2 shows the thermal evolution of Tb5Si2Ge2 when the field is increased from 0 to 5 T in steps of 1 T. In a

constant field, the thermal drift due to small errors of adiabaticity is typically lower than 0.2 K/hour. It can be corrected observing the slope of T(t) at constant field so that the accuracy in ∆TS is about 0.02 K, better than 1% in the interesting MCE ranges.

Materials suitable for magnetic cooling should have a large angular and magnetic moment and Tc near the working temperature, most frequently room temperature. They must also be good thermal conductors in order to give a fast heat exchange.

The first prototypes of magnetic refrigeration machines used pure Gd metal, which has Tc = 294 K and applied fields of 7 T. The application of the MCE for refrigeration has been considered as a competitive and alternative method since the discovery of the so called giant magnetocaloric effect (GMCE) in Gd5Si2-xGe2+x 3. For compositions near x = 0 this alloy undergoes a first-order transition from a paramagnetic monoclinic phase to a ferromagnetic orthorhombic one at 276 K. The transition can be induced at slightly higher temperatures by the application of an external field. The entropy change is due to the alignment of the magnetic moments and a large volume contraction in the ferromagnetic phase. As a result, the entropy change is about twice larger than in pure Gd metal. Moreover, the transition temperature can be tailored between 130 K and 280 K by choosing the composition x, what allows adjusting the working temperature and a good regeneration process, expanding the difference between the hot and cold sources.

The use GMCE compounds allows working with moderate fields, attainable by conventional electromagnets, and making the procedure competitive with respect to the gas compression-expansion cycles. Additionally, the GMCE based refrigeration is about 20 % more efficient than the conventional procedure, which implies some energy saving. Moreover, the mechanical design is simpler, using a low pressure innocuous fluid as a heat exchanger.

Since the report on Gd5Si2-xGe2+x many other compounds are being studied that could be suitable for working in other temperature ranges. In the family R5Si4 where R is a rare earth atom, the gradual substitution of Tb for Gd decreases the transition temperature, whereas the substitution of Si by Ge increases ∆ST.

The RNi2 and RAl2 compounds have proved to be good magnetic refrigerants in the low temperature range, 10 K to 100 K.

Mn3GaC has the perovskite structure with a first-order transition at T0 = 160 K from an antiferromagnetic phase in the low temperature region to a ferromagnetic one. The transition can be induced below T0 by an external field. Direct measurements of the MCE (Figure 3) have shown high negative ∆TS, independent of the field intensity above a threshold value 4. The threshold field increases with decreasing temperature below T0 but the MCE is constant in a wide temperature range.

Other interesting families are MnAs, MnFeP1-xAsx, Fe0.49Rh0.51 and the Heusler alloys Ni2+xMn1-yGa1-x+y (x,y <<1) which have magnetic form memory effects.

Acknowledgements Financial support from the Spanish Ministerio de Ciencia y Tecnología, Project MAT2001-3507-C02-02. References 1 S. Yu Dan’kov, A. M. Tishin, V. K. Pecharsky, K. A. Geschneidner Jr. Rev. Sci. Instr. 1997, 68, 2432. 2 L. Tocado, E. Palacios, R. Burriel. 6th Mediterranean Conference on Calorimetry and Thermal Analysis MEDICTA 2003, Oporto (Portugal), August 2003, 135. 3 V. K. Pecharsky, K. A. Geschneidner Jr. Phys. Rev. Lett. 1997, 78, 4494. 4 R. Burriel, L. Tocado, E. Palacios, H. Wada. Joint European Magnetic Symposia JEMS’04, Dresden (Germany), 2004.

130 140 150 160 170

-1

0

1

Figure 3. Adiabatic temperature increment in Mn3GaC, for several positive and negative field increments.

∆TS (

K)

T(K)

0 to 1T 1T to 0 0 to 3T 3T to 0 0 to 5T 5T to 0

0 500 1000

104

105

106

107

Figure 2. Adiabatic temperature change in Tb5Si2Ge2

3 T

5 T

4 T

2 T

1 T

H = 0

∆ TS

time(s)

T(K)

53

SYNCHROTRON X-RAY RESONANT SCATTERING IN METALLIC OXIDES: CHARGE AND ORBITAL ORDERING

J. García, G. Subías, J. Blasco, M. G. Proietti, M. C. Sánchez, J. Herrero-Martin

Mixed-valence transition-metal (TM) oxides exhibit many interesting properties such as superconductivity, colossal magnetoresistance and metal-insulator phase transitions. Generally, the description of the electronic state of these compounds is made on the basis of the ionic model proposed by Goodenough and it implies the spatial or temporal charge localization on the transition-metal atoms. Following this framework, the low temperature insulating phases of these oxides have generally been described as a periodic ordering of distinct ionic states in the lattice. This phenomenology, so-called charge ordering (CO), has become nowadays a main topic in the description of TM oxides, such as manganese perovskites. Intimately related to the charge ordering, it has also been proposed the concept of orbital ordering (OO), as the orientational ordering of the d-orbitals of the transition-metal atoms in the lattice. The two archetype examples of charge and orbital ordering are Fe3O4 (magnetite) and LaMnO3 (the mother compound of magnetoresistive manganites), respectively. The characterization of the charge-orbital-ordering (COO) phenomena is a hard and controversial task up to now. Generally, the observation of different crystallographic sites by either x-ray or neutron diffraction techniques has been considered as a proof of charge ordering. A direct way to demonstrate the onset of a long-range periodic charge arrangement is the observation of superlattice reflections by the recently developed X-ray Resonant Scattering technique in modern synchrotron radiation facilities. The appearance of a resonance at the transition-metal K absorption edge is due to the out-of-phase interference of identical (or almost) crystallographic sites because of the difference in the atomic anomalous scattering factors f. The anomalous part of the scattering factor, f'(E) + if"(E), is related to the x-ray absorption coefficient µ. For dipolar transition, resonant reflections can then originate by either the different energies of s-p excitations for atoms with different valence states (CO reflections) or by the directional splitting of the p-unoccupied states in an anisotropic local environment (Anisotropic Tensor of Susceptibility, ATS, reflections, often associated to OO reflections). In the course of our research, we have investigated the COO phenomena carrying out X-ray Resonant Scattering experiments in two relevant systems. The first one includes Fe3O4 and related spinel ferrites. The second one is Nd0.5Sr0.5MnO3 as example for half-doped manganites. Both systems showed a metal-insulator phase transition with decreasing the temperature, the low temperature phase being described as a COO phase. We have shown that the observed resonant reflections in the two

systems can be easily explained only considering the anisotropy of the local geometrical structure around the excited TM atom. Magnetite was the first material where a CO transition was proposed to explain the insulator behaviour below TV ∼ 120 K (Verwey transition). It crystallizes in the spinel cubic structure (space group Fd-3m) at room temperature. The formula unit can be written as Fe3+[Fe2+,Fe3+]O4 where the bracket indicates atoms located at the octahedral sites while cations outside the bracket are at the tetragonal sites. According to this formula, 2+ and 3+ Fe ions are dynamically disordered at the same crystallographic site. This dynamical transformation of Fe2+ into Fe3+ implies the motion of the electron to be responsible for the metallic conductivity. Then, the insulator behaviour was explained in terms of localization of the mobile electron at the octahedral sites, giving rise to a long range spatial CO pattern (Verwey model). Spinel ferrites are obtained from Fe3O4 by partial substitution of the Fe ions by other divalent cations. In particular, Co2+ locates at the octahedral site in CoFe2O4 whereas Mn2+ occupies the tetrahedral site in MnFe2O4. X-ray resonant scattering experiments were carried out on Fe3O4

1,2, MnFe2O4 and CoFe2O4 single crystals, grown by floating zone method in our laboratory, at the beam-line D2AM at the ESRF (Grenoble, France). Symmetry forbidden (002) and (006) reflections were measured at room temperature, below TV and in the case of magnetite, above the Néel temperature (TN) in order to check any effect associated to the onset of the ferrimagnetism. The azimuthal angle (rotation around the scattering vector Q=k'-k) dependence and polarization analysis (σ-σ’ and σ-π’ components for σ–polarised incident bem) of the scattered intensity were also analysed. Figure 1 compares the energy dependence of the diffracted intensity of (002) and (006) reflections at the Fe K-edge at room temperature for the three spinel ferrites. The spectra shows three main features whose origin we have determined experimentally: a pre-edge resonance (dipole-quadrupole transitions at the tetrahedral Fe ion), a main resonance at the absorption K-edge and an energy extended modulation (dipole transitions at the pseudo-octahedral metal ion). The dipolar part of the spectra has been analysed using a tensorial formalism for the anomalous scattering factor. In the local frame of the pseudo-octahedron, trigonal-distorted, the scattering tensor is diagonal with two main components, parallel and perpendicular to the trigonal axis. This analysis reproduces well the energy, azimuthal and polarization dependences. Moreover, the energy-dependent spectra at temperatures

54

below TV or above TN in magnetite are identical to the room temperature one.

Figure 1. Energy dependence spectra of (002) [closed symbols] and (006) [open symbols] reflections. Solid lines are the respective fluorescence spectra. Lines are a guide for the eye and asterisks mark spurious Renninger reflections. All these results show: First, the atomic scattering factor is identical among the different octahedral atoms in magnetite pointing out to the lack of charge localization (temporal or spatial) in the sense of bimodal CO of ionic states. Secondly, the anisotropy of the anomalous scattering factor is mainly originated by the anisotropy of the local geometrical symmetry of the octahedral atom instead of a supposed 3d orbital ordering. In the case of half-doped manganites, several x-ray resonant scattering studies have claimed on the observation of real COO phases. However, neither our previous XANES (X-ray Absorption Near Edge Structure) measurements on these manganites nor a proper re-examination of the x-ray resonant scattering data reported in the literature 3,4 supported this electronic localization at atomic scale. We have recently performed a X-ray resonant scattering experiment at the beam line ID20 at the ESRF (Grenoble, France) at the Mn K-edge in a Nd0.5Sr0.5MnO3 single-crystal 5, also grown by floating zone method in our laboratory. The low temperature phase of this compound has also been described as a COO phase within a checkerboard pattern of Mn3+ (Jahn-Teller ion) and Mn4+ ions according to the antiferromagnetic CE-type phase below TN ~170 K. We observe dipole resonance at the Mn K-edge for the low temperature superlattice (300) and (030) [assigned to CO] and forbidden (05/20) [assigned to OO] reflections. The energy, azimuthal angle and polarization dependences of these reflections have nicely been analysed using a semi-empirical structural model for the tensorial atomic scattering factors: Two non-equivalent crystallographic octahedral sites are found for the Mn atoms below TN, (1) tetragonal-distorted [described with two components in the diagonal, f1par and f1perp to the tetragonal axis]

and (2) nearly-regular [the three components in the diagonal are identical, f2]. Figure 2 compares the x-ray scattering data to the best-fit semi-empirical model, obtained for δanis = f1par- f1perp = 1.6 eV and δchem = f1- f2 = 0.7 eV, for both the supposed “CO” and “OO” reflections. Although the experiment probe the existence of two kinds of Mn atoms, we demonstrate that they cannot be identified as (1) Mn3+ and (2) Mn4+ ions with a δchem = f1- f2 = 4.5 eV determined from XANES spectroscopy. Then, the “CO” reflections are naturally explained by the different local geometry of the two Mn sites and the “OO” reflections as due to the anisotropy of the tetragonal local distortion at one of the Mn sites without including any ordering of the Mn d-orbitals, i.e. Jahn-Teller effect.

Figure 2. Energy dependence spectra of (030) and (05/20) reflections at the Mn K-edge at T=60 K (symbols) compared to the best-fit structural model (lines) at maximum and minimum azimuthal ϕ angles. Summarizing, we conclude that no charge localization occurs on the transition-metal atoms in either magnetite or the half-doped NdSr-manganite. This result might force the scientific community to change the atomic concept of electronic localization in mixed-valence TM oxides 6. Acknowledgements This work was partially supported by the CICyT MAT-02-0121 project and DGA. References and Principal publications 1 J. García, G. Subias, M. G. Proietti, H. Renevier, Y. Joly, J. L. Hodeau, M. C. Sánchez, J. F. Bérar. Phys. Rev. Lett. 2000, 85, 578. 2 J. García, G. Subias, M. G. Proietti, J. Blasco, H. Renevier, J. L. Hodeau, Y. Joly. Phys. Rev. B 2001, 63, 054110. 3 J. García, M. C. Sánchez, J. Blasco, G. Subías, M. G. Proietti. J. Phys. Condens. Matter 2001, 13, 3243; J. García, M. C. Sánchez, G. Subías, J. Blasco. J. Phys. Condens. Matter 2001,13, 3229. 4 J. García, G. Subías, Phys. Rev. B 2003, 68, 12701. 5 J. Herrero-Martin, J. García, G. Subías, J. Blasco, M. C. Sánchez. Phys. Rev. B 2004, 70, Art nº 024408. 6 J. García, G. Subías. J. Phys. Condens. Matter 2004, 16, R145.

55

NEW OPPORTUNITIES IN TRACE ELEMENTS STRUCTURAL CHARACTERIZATION: HIGH-ENERGY X-RAY ABSORPTION NEAR-EDGE STRUCTURE SPECTROSCOPY.

J. Chaboy

Modern synchrotron radiation facilities provide indispensable tools for research in a large number of different fields of science like Physics, Chemistry, Biology, as well as in Materials-, Geo- and Environmental Sciences. One of the outstanding techniques associated to synchrotron radiation sources is x-ray absorption spectroscopy (XAS). XAS spectroscopy has been demonstrated to be essential to progress in many scientific fields as it provides, by taking advantage of its highly-flexible experimental capabilities, the knowledge of the local atomic structure of a selected atomic species in the material under study. Over the last years we have seen the development of the so called third generation sources. One of the main challenges within the new facilities connected to XAS is the extension of the available high-energy range. Indeed, the use of XAS as a dedicated tool to determine local structural environments has previously been confined to absorption edges below 30 keV. Recent works have demonstrated that it is possible to measure XAS spectra with sufficiently high signal to noise ratios in the energy range 30 to 90 keV 1. Despite the above advantages there are still only few works dealing with high-energy XAS and most of them still deal with qualitative and fingerprint analyses. The main reason for this lack of experimental work seems to be linked to the assumption that the finite lifetime of the core-hole smears out dramatically the spectral features so as to avoid structural determination, and that this effect becomes more serious for K-absorption edges of heavier elements 2. In this work we present the first quantitative analysis made on the x-ray absorption near-edge structure (XANES) region at the Nd K-edge in natural minerals containing Nd in trace concentrations. Among the rock forming minerals, aluminosilicate garnets (X3Y2Si3O12, X=Fe2+, Mn2+, Mg, Ca) are intensly studied both due to the complexity of their crystal chemistry and to theirstability over a wide range of physico-chemical parameters 3. Garnets in lower crustal mafic and ultramafic rocks usually contain rare-earth elements (REE) in trace concentrations. The diffusion coefficients of REE between garnets and the coexisting phases are used to interpret the crystallization and metamorphic history of crustal rocks. An understanding of REE diffusion in garnets cannot be obtained without a characterization of their structural behavior. Despite their geochemical importance, a direct crystal chemistry characterization of REE at trace levels in natural garnets is not available in literature because of the difficulty of obtaining structural information on elements present in so low

concentration by means of conventional diffraction methods. The goal of this work is twofold. On the one hand we provided an exact structural determination about which is the position that Nd enters in the complicated mineral framework. On the other hand we demonstrate the capability of the XANES technique to solve different structural environments, being this capability not affected by the damping and broadening of the signal due to the short lifetime of the excited atomic state. We have studied the local environment of Nd at trace levels in a series of natural garnets belonging to the pyrope-grossular solid-solution and containing different Nd concentrations (176-1029 ppm). The samples are melanite garnets occurring in carbonatitic rocks and labelled A204, V19 and 89/35. Samples exhibit different Nd concentration, as determined by ionic microprobe analysis, being 1029, 344 and 176 ppm for A204, V19 and 89/35 respectively. The chemical compositions of the A204, V19 and 89/35 samples are respectively: X:(Ca2.91Mg0.04Mn0.02Na0.03)Y:(Mg0.10Ti0.89Zr0.04Al0.28Fe3+

0.69) Z:(Si2.34Fe3+0.66)O12

(Ca2.89Mg0.05Mn0.02Na0.04)(Mg0.08Ti0.83Zr0.03Al0.20Fe3+

0.86)(Si2.47Fe3+0.53)O12

(Ca2.97Mg0.03Mn0.03Na0.01)(Mg0.09Ti0.49Zr0.02Al0.26 Fe3+

1.14)(Si2.66Fe3+0.34)O12

with trace concentrations of Ce of 755, 257 and 159 ppm, respectively. XAS measurements at the commonly used Nd L3-edge (~6208 eV) are unattainable in these samples, due to the presence of interfering fluorescence lines from the matrix and by the presence of the Ce L2-edge (6164 eV) close to the Nd L3-edge, with a Ce concentration similar to that of Nd. These problems can be overcome by use of the Nd K-edge (~ 43570 eV), since at this energy there are no problems of overlapping of absorption edges and fluorescence lines. This problem illustrate the significant interest of XAS into the possibility of working at high energy. The Nd K-edge spectra were collected at 77 K in transmission mode on the reference compound Nd(OH)3, and in fluorescence mode on powdered samples of the three natural garnets at the ESRF GILDA BM8 CRG beamline. The energy resolution was about 5.4 eV at 43.5 keV. Figure 1 reports the raw Nd K-edge XAS spectra for the three garnets under study. The XAS oscillations are clearly visible above the edge. Therefore, the Nd K-edge XANES spectra can be used to perform a quantitative determination of the local environment of trace Nd in these garnets. The comparison of the XANES region indicates also that the structural

56

environment of Nd is the same for the three garnets.

Figure 1. Detailed comparison of the Nd K-edge XANES region for the 3 garnets under study. The computation of the Nd K-edge absorption cross-section was carried out using the multiple-scattering CONTINUUM according to standard FMS methods 4. The Coulomb part of each atomic potential was generated using charge densities for neutral atoms. The atomic orbitals were chosen to be neutral for the ground state potential, whereas we follow the Z+1 rule to build the excited state potential. Finally, an appropriate exchange and correlation (ECP) potential was added to the Coulomb part of the input potential. Initially, we have considered two different possibilities for the position that trace Nd enters in the X3Y2Si3O12 garnet structure. Hence, we have built-up two class of clusters assuming that Nd enters the dodecahedral X-site and the octahedral Y-site, respectively. The calculations performed by using a real Hedin-Lundqvist ECP spectra reproduce all the features present in the experimental spectra, their relative intensity and their relative energy separation. After taking into account the effect of the core-hole lifetime (17.3 eV) and the experimental resolution, the agreement between the computation and the experimental XANES is remarkable. Figure 2 shows the comparison between the Nd K-edge XANES spectrum of the garnet with a Nd content 1029 ppm (A204) and the theoretical computations performed by assuming that Nd enters the octahedral and dodecahedral sites. It should be noted that the energy scale of each computation is referred to its own muffin-tin potential so that calculation provides an unique energy scale to align both X- and Y-site theoretical spectra. The results of the computation strongly suggest that trace Nd enters the dodecahedral X-site. The same comparison made after convolution of the theoretical spectra with the full core-hole width

not only validates this result, but also shows convincely that the structural determination is not affected by the damping and broadening of the signal due to the short lifetime of the excited atomic state.

Figure 2. Comparison between the experimental Nd K-edge XANES signal of A204 and those calculated on the basis of the FMS theory assuming Nd in the dodecahedral (X-site) or in the octahedral (Y-site) sites after taking into account the full Nd K-edge core-hole width.

Summarising, the study of the high-energy K-edge x-ray absorption of Nd occurring in trace concentrations in natural garnets demonstrates that Nd enters a structural garnet site and does not occupy matrix defects. Indeed, Nd enters the dodecahedral X-site of the X3Y2Si3O12 garnet structure and does not substitute Al at the octahedral Y-site. Therefore we provide a direct crystal chemistry characterization of rare-earths elements at trace levels in natural garnets not available in literature. Moreover, the capability of high-energy XANES as powerful structural tool providing structural details unattainable by using standard methods has been demonstrated.

Principal publication J. Chaboy, E. Cotallo, S. Quartieri, F. Boscherini. J. Synchrotron Rad. 2002, 9, 86

Acknowledgements This work was partially supported by the Aragón DGA (P0004/2001), Spanish DGICYT (MAT99-0667-C04-04) grants. References 1 M. Braglia, G. Dai, S. Mosso, S. Pascarelli, F. Boscherini, C. Lamberti. J. Appl. Phys. 1998, 83, 5065. 2 D. G. Stearns. Philos. Mag. B 1984, 49, 541. 3 W. van Westrenen, J. Blundy, B. Wood. Amer. Mineral. 1999, 84, 838. 4 J. Chaboy, S. Quartieri. Phys. Rev. B 1995, 52, 6349. 5 S. Quartieri, J. Chaboy, G. Antonioli, C. A. Geiger. Phys. Chem. Minerals 1999, 27, 88.

57

PRESSURE-INDUCED THREE-DIMENSIONAL FERROMAGNETIC CORRELATIONS IN THE GIANT MAGNETOCALORIC COMPOUND Gd5Ge4

C. Magén, L. Morellón, P. A. Algarabel, M. R. Ibarra

Gd5(SixGe1-x)4 is a unique class of materials where many interesting properties and intriguing behavior have been recently discovered 1. The unprecedented giant magnetocaloric effect 2, strong magnetoelastic effects 3,4, and giant magnetoresistance 5,6 can be highlighted as the most relevant. This phenomenology has been associated with the intrinsically layered crystallographic structure combined with a magnetic-martensitic first-order phase transformation 7. The coupled magnetic-crystallographic transition can be induced reversibly by the change of external parameters such as temperature or external magnetic field 1,4. Therefore, these alloys are attractive for their potential applications in magnetic refrigeration and/or as magnetostrictive/magnetoresistive transducers.

Three extended solid solution regions exist in the temperature-composition (T–x) phase diagram 8,9: the Si-rich solid solution, 0.575≤x≤1, has the orthorhombic Gd5Si4-type structure [O(I)]; the intermediate phase 0.4<x≤0.503 has a room temperature monoclinic (M) structure; and the Ge-rich region, 0<x≤0.3 crystallizes in the Gd5Ge4-type structure [O(II)]. All three structures are composed of identical two-dimensional (2D) sub-nanometer-thick layers (slabs) interconnected via partially covalent inter-slab X–X bonds (X = Si, Ge). In the O(I) structure, all the slabs are interconnected by X–X bonds; half of these bonds are broken in the M structure and none remain in the O(II) structure. The magnetic-crystallographic transition involves breaking/reforming specific covalent X–X bonds 7 and the low-temperature ground state for all compositions 0<x≤1 is always ferromagnetic (FM) with all the slabs being interconnected, i.e. with the O(I) structure. The M structure is always paramagnetic (PM) whereas the O(II) can support either PM or antiferromagnetism (AFM) 4,9. The magnetic behavior of the R5(SixGe1-x)4 compounds can be understood qualitatively in terms of competition between intralayer (within the 2D slabs, conventional indirect 4f-4f RKKY) and interlayer exchange interactions (between slabs, direct Gd-Si/Ge-Gd superexchange propagated via the X-X bonds) 1,10.

In sharp contrast with the magnetic behavior of the Ge-rich compounds no FM phase is observed in Gd5Ge4 in zero magnetic field and down to the lowest measured temperature 11,12. Gd5Ge4 orders antiferromagnetically at ∼ 130 K, this system presenting a very complex magnetic field-temperature (H–T) phase diagram and an interesting magnetoelastic behavior 13. A fully irreversible field-induced O(II) (AFM) → O(I) (FM) transformation takes place below ≈ 10 K, this becoming fully reversible above ≈ 20 K. Between ≈ 10 K and ≈ 20 K the field-induced transition is partially reversible and a spatially

phase-segregated O(II) + O(I) state is found at low temperatures.

The aim of this work is to investigate the possibility to induce three-dimensional (3D) ferromagnetic correlations in Gd5Ge4 upon application of an external hydrostatic pressure.

In Fig. 1 we display the linear thermal expansion (LTE) of Gd5Ge4 at different values of the applied hydrostatic pressure. Upon application of pressure, a distinct anomaly develops in the LTE curve and a clear jump is detected at higher pressure values. According to our investigation of the magnetoelastic behavior of this compound 13, this anomaly signals the existence of a pressure-induced low-temperature O(I)–FM phase, the amount of this phase being reflected in the magnitude of the jump.

FIG. 1. Linear Thermal Expansion as a function of temperature under selected values of the applied hydrostatic pressure. In the inset the relative change in volume of the sample at selected temperatures is displayed.

In order to correlate the structural behavior

with the magnetic properties we have carried out a systematic study of the magnetism of Gd5Ge4 as a function of temperature, applied magnetic field and applied hydrostatic pressure. In Fig. 2 we display the temperature dependence of the magnetization in an applied field of 500 Oe at selected values of the applied hydrostatic pressure: 0, 1.3, and 8 kbar. As expected 11-13, at ambient pressure no FM state is detected down to 5 K (open circles) but application and removal of 50 kOe at 5 K induces a FM state that remains up to ≈ 14 K (open squares). As is clearly seen in Fig. 3, an applied hydrostatic pressure of 1.3 kbar is sufficient to induce a FM signal at ≈ 35 K (heating), the value of which at 5 K is much lower than that obtained when applying and removing 5 T at ambient pressure. Therefore, from this and the results in Fig. 1, we can interpret this data supposing that the sample volume at 1.3 kbar is spatially phase segregated into O(II)–AFM and O(I)–FM regions, i.e. 1.3 kbar is sufficient to enhance the interlayer interactions favoring 3D FM correlations. As far as we know, this is the first time phase-separation phenomena have been observed in a

-4.0

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0 25 50 75 100 125 150

Line

ar T

herm

al E

xpan

sion

(10-3

)

Temperature (K)

1 kbar

2.6 kbar

5.9 kbar

10.9 kbar8.1 kbar

0.9750.9800.9850.9900.9951.000

0 2 4 6 8 10 12 14∆

V/V

P (kbar)

20 K

100 K295 K

58

pure 4f localized-moment system upon application of hydrostatic pressure. If we apply and remove isothermally a magnetic field of 50 kOe at 5 K and 1.3 kbar, a full FM signal is recovered (solid squares). Should this physical picture be correct, a higher pressure should increase the relative volume of the O(I)–FM regions. This is indeed the case since the FM signal at 8 kbar is almost maximum. We therefore propose that a hydrostatic pressure of 8 kbar is able to induce a O(I)–FM ground state in the majority of the sample with a TC ≅ 65 K (heating).

0

5

10

15

20

0 25 50 75 100 125 150 175

Mag

netiz

atio

n (e

mu/

g)

Temperature (K)

8 kbar

0 kbar

1.3 kbar

after applying and removing 50 kOe at 5 K

Hdc

= 500 Oe

TN

TC

FIG. 2. Magnetization in an applied field of 500 Oe as a function of temperature under selected values of the applied hydrostatic pressure. Black arrows indicate the direction of temperature change.

The relative percentage of the pressure-

induced O(I)–FM phase can be estimated from magnetization measurements. The final values are displayed in Fig. 3 (solid circles) together with the results obtained from the LTE data, see Fig. 1, assuming that the jump in the LTE at 10.9 kbar corresponds to a 100% of O(I)-FM transformed phase at low temperatures. As can be seen the results are in very good agreement, this being a strong evidence of the physical picture presented to interpret the LTE and magnetization results as a function of pressure. From the results in Fig. 3 we can be quite confident that at pressures above ≈ 10 Kbar the entire volume of the sample at low temperatures below TC (10 Kbar) ≅ 53 K is FM crystallizing in the O(I) structure.

In conclusion, we have explored the possibility to induce 3D ferromagnetic correlations in the giant magnetocaloric alloy Gd5Ge4 by means of LTE and magnetic measurements at different applied pressures. As a main result, application of hydrostatic pressure induces a spatially phase-segregated ground state where O(I)–FM and O(II)–AFM regions coexist within the sample volume. It has been predicted that at pressures of over 10 kbar, the low-temperature O(I)–FM ground state is stabilized in the entire sample volume.

0

20

40

60

80

100

0 2 4 6 8 10 12

Pres

sure

-indu

ced

O(I

)–FM

pha

se (%

)

Pressure (kbar)FIG. 3. Percentage of pressure-induced O(II)-FM phase as estimated from LTE results (open circles) and magnetization measurements (solid circles). The line is a guide for the eye.

We propose a physical picture where the

effect of pressure is to reduce the interatomic distances, thus enhancing the interlayer interactions in this naturally nanolayered material. This should favor the formation of specific covalent bonds, inducing a first-order pressure-induced magnetic-crystallographic transformation from an O(II)–AFM to an O(I)–FM structure. Main publication C. Magén, Z. Arnold, L. Morellón, Y. Skorokhod, P. A. Algarabel, M. R. Ibarra, J. Kamarad. Phys. Rev. Lett. 2003, 91, 207202.

Acknowledgements The finantial support of Grant No. MAT2000-1756 is acknowledged. References 1 V. K. Pecharsky, K. A. Gschneidner, Jr. Adv. Mater. 2001,13, 683. 2 V. K. Pecharsky, K. A. Gschneidner, Jr. Phys. Rev. Lett. 1997,78; Appl. Phys. Lett. 1997, 70, 3299; J. Magn. Magn. Mater. 1997, 167, L179. 3 L. Morellón et al. Phys. Rev. B 1998, 58, R14721. 4 L. Morellón et al. Phys. Rev. B 2000, 62, 1022. 5 L. Morellón et al. Appl. Phys. Lett. 1998, 73, 3462; J. Magn. Magn. Mater. 2001, 237, 119. 6 E. M. Levin, V. K. Pecharsky, K. A. Gschneidner, Jr. Phys. Rev. B 1999, 60, 7993. 7 W. Choe et al. Phys. Rev. Lett. 2000, 84, 4617. 8 V. K. Pecharsky, K. A. Gschneidner, Jr. J. Alloys Comp. 1997, 260, 98. 9 A. O. Pecharsky et al. J. Alloy Comp. 2002, 338, 126. 10 E. M. Levin, V. K. Pecharsky, K. A. Gschneidner Jr. Phys. Rev. B 2000, 62, R14625. 11 E. M. Levin, K. A. Gschneidner, Jr., V. K. Pecharsky. Phys. Rev. B 2001, 65, 214427. 12 E. M. Levin et al. Phys. Rev. B 2001, 64, 235103. 13 C. Magén et al. J. Phys. Condensed Matter 2003,15, 2389.

59

SUPERCONDUCTING PROPERTIES OF METAL/MgB2 COMPOSITE WIRES

E. Martínez, L. A. Angurel, A. Millán, R. Navarro

The development of materials with the new MgB2 superconductor 1, which has critical temperatures of Tc=39 K, has opened great expectations. This is because it is a suitable candidate for large-scale electrical applications such us magnets for Magnetic Resonance Imaging, transformers, motors, generators… operating in the range of 20-30 K, easily reachable with cryocoolers.

A key support of this interest arose from the conformation of long metal/MgB2 composite wires and tapes with high critical currents densities (Jc=109-1010 A/m2) using well-known powder-in-tube (PIT) methods. Because its potential scalability and production flexibility, these technologies are attractive and inexpensive for long-wire fabrication.

Jc, which is the maximum current per unit area that the superconductor wire can carry without energy losses, is one of the most important parameters for the characterisation of such conductors. Jc decreases under applied magnetic fields, B, reducing to zero at a value called irreversibility field, Birr.

Currently, MgB2 materials have relatively low Birr values (4-6 T at 20 K), hence special efforts are being made to improve the superconducting behaviour under high fields. Some groups have reported improvements of the Jc(B) dependence by neutron irradiation of the samples 2, by using ball-milled powders 3 and by doping with nano-particles (10-30 nm) such as SiC 4 and diamond5.

In the PIT technique, mixtures of unreacted Mg and B powders, the so called in situ reaction approach; or pre-reacted MgB2 powders, ex situ reaction technique, are packed inside metal tubes (in our case, typically of 4.0 mm outer diameter and 2.5 or 3.0 mm inner ones). Subsequently the tubes are cold drawn in round dyes down to 1.2 mm of diameter in 0.1 mm reduction steps. The final wires have core diameters of 0.6 or 0.8 mm, depending on the initial inner diameter of the tubes. Finally the wires are annealed in argon, to prevent oxidation, in order to react (in situ) or sinter (ex situ) the core precursors.

The selection of adequate sheaths for these composites, giving thermal, electrical and mechanical stability, constitutes nowadays an open issue to be addressed prior to reach technologically useful metal/MgB2 conductors. Different metal sheaths have already been used: Fe, Cu, Ni, Ag, Cu-Ni alloys and stainless steel (SS), as well as different metal combinations such as: (from outside to inside) Cu/Ta and SS/Cu/Fe (for a review see for instance 6). Up to now, the highest Jc(B,T) values are obtained with hard metal sheaths that do not react with Mg or MgB2, such as steel and iron, but these wires, as consequence of a poor thermal stability, easily transit to normal state (quench)

at Jc > 109 A/m2. Moreover, silver sheathed wires present very poor results compared with copper or nickel sheathed wires and therefore have been disregarded.

Here, we report on the superconducting properties of Cu- and Ni-sheathed MgB2 mono-filament wires fabricated in the ICMA by the PIT technique using the in situ and ex situ procedures, respectively. Both are interesting sheath candidates due to their properties of ductility, soldability and good thermal conductivity.

Figure 1: Longitudinal SEM images of (a) ex situ Ni/MgB2 wire annealed at 850 ˚C during 0.5 h; and (b) in situ Cu/MgB2 annealed at 700 ˚C during 0.5 h. The circle in b) indicates the main phase containing MgB2.

A typical SEM longitudinal cross-section of Ni/MgB2 and Cu/MgB2 composite wires after annealing is shown in Figure 1. In both cases the superconducting cores have irregular shape. This is partially produced during mechanical conformation because the lower hardness of the sheath with respect to the precursors (particularly, boron and MgB2), but it would be also due to the reactivity of the precursors from the core with the inner sheath wall during the heat treatment.

A reaction layer adjacent to the superconducting core, with darker contrast and 20 to 30 µm thickness, is observed for both wires. EDX and X-Ray analyses have indicated that this layer corresponds to MgNi2 and MgCu2 while the rest of the sheath remains pure nickel

60

and copper, respectively. Nevertheless, the ex situ Ni/MgB2 wires presents more homogeneous microstructures than the Cu-sheathed ones, which also show MgCu2 grains homogeneously dispersed inside the core, with sizes typically ranging from 20 to 80 µm.

107

108

109

1010

0 1 2 3 4 5

x=0.2, 700ºC, 18minx=0, 700ºC, 30minx=0.2, 700ºC, 18min, q

J C,M

(A

/m2 )

B (T)

5 K20 K

Cu/MgB2

in situ

(a)

107

108

109

1010

0 1 2 3 4 5

MgB2

MgB1.8

(SiC)0.1

J C,M

(A

/m2 )

B(T)

5 K

20 K30 K(b)

Ni-sheatedex situ

Figure 2. Magnetic field dependence of the critical current density, Jc,M(B), estimated from the M-B hysteresis loops at different temperatures for the Cu- (a) and Ni-sheathed wires (b) annealed at 850 ºC during 0.5 h. ‘q’ in (a) means quenched at room temperature.

The field dependences of the critical current density estimated form the magnetization hysteresis curves, Jc,M(B), are shown in Fig. 2. Note that for these wires, Jc values of 109 A/m2 would correspond to currents of 500-600 A.

Ni-sheathed wires show a superconducting behaviour better than Cu ones, having higher Jc values and less sharp Jc(B) decays. This way, Jc,M decreases down to 108 A/m2 for magnetic fields of 3 and 2 T at 20 K, for the Ni- and Cu-sheathed wires, respectively.

For the same sheath material, the annealing conditions only affect the Jc values but not their field dependence, indicating that these parameters, for the used range here, do not change the pinning mechanisms. For the Cu-sheathed wires, it has been observed that an excess of Mg over the stoichiometric proportions (x in fig. 2-a, given in atom.%) results in an improvement of Jc by the increase of the amount of superconducting phases

From our results (Fig. 2-b), it is clear that doping with SiC nano-particles (20 nm average size) is also effective in improving the Jc(B) decays when using the ex situ procedure instead

of the in situ reaction originally used in [4], obtaining Jc,M>108 A/m2 for B<3.7 T at 20 K. The superconducting behaviour of Ni-sheathed wires shows that nickel may be a valuable alternative to iron for practical applications. Nevertheless, non-magnetic Ni based alloy would be preferable. Moreover, it has to be noted that Ni would not be suitable with in situ procedures because of the important reactivity of Mg and Ni. Therefore, doping would require either the ex situ method or the use of diffusion barriers between the core and the Ni sheath. The lower performance of Cu/MgB2 wires would be due to the in situ reaction it-self and to the reactivity between the Cu sheath and the Mg precursors together with the insufficient hardness of copper. Nevertheless, main advantages of these MgB2/Cu wires are certainly related to the good thermal stability given by the high thermal conductivity of the sheath. This allows carrying out transport measurements up to high currents (500-700 A at 15-20 K) without quenching, even without surrounding cryogenic liquid or gas to thermalise the sample, which is very unlikely on wires with others sheaths such as iron, stainless steel, nickel, etc. Our future efforts are focused in the search of conductors thermally stable and with high performance at fields between 5 to 10 T, both necessary for technical applications.

Principal publications E. Martínez, L. A. Angurel, R. Navarro. Supercond. Sci. Technol. 2002, 15, 1043 E. Martínez, A. Millán, R. Navarro. European Conference of Applied Superconductivity, EUCAS, 2003.

Acknowledgements The financial support of the Spanish CICYT projects MAT-1999-1028 and MAT-2002-04121-C03-02 is acknowledged. References 1 J. Nagamatsu, N. Nakagawa, T. Murakanaka, Y. Zenitani. Nature 2001, 410, 063. 2 M. Eisterer, B. A. Glowacki, H. W. Weber, L. R. Greenwood, M. Majoros. Supercond. Sci. Technol. 2002, 15, 1088. 3 R. Flükiger, P. Lezza, C. Beneduce, N. Musolino, H. L. Suo. Supercond. Sci. Technol. 2003, 16, 264. 4 S. H. Zhou, A. V. Pan, M. J. Qin, H. K. Liu, S. X. Dou. Physica C 2003, 387, 321. 5 C. H. Cheng, H. Zhang, Y. Zhao, Y. Feng, X. F. Rui, P. Munroe, H. M. Zeng, N. Koshizuka, M. Murakami. Supercond. Sci. Technol. 2003,16, 1182. 6 R. Flükiger, H. L. Suo, N. Musolino, C. Beneduce, P. Toulemonde, P. Lezza. Physica C 2003, 385, 286.

61

PHOTO-INDUCED CHIRALITY ON ACHIRAL SIDE CHAIN LIQUID CRYSTALLINE

POLYMETHACRYLATES

L. Oriol, M. Piñol, R. M. Tejedor, J. L. Serrano, R. Alcalá, F. J. Rodríguez, B. Villacampa

Azobenzene side-chain liquid crystalline polymers (azo-SCLCPs) have received considerable attention as promising materials in the field of photonics, i.e. holographic storage, optical switching, or as light-driven aligning layers of liquid crystals1. All these applications derive from the possibility of changing the orientation of the azobenzene chromophores through the photoinduced trans-cis-trans isomerization of azobenzene units. The irradiation is usually carried out with linearly polarized light giving rise to a reorientation of the azo chromophores perpendicular to the laser polarization direction. Furthermore, in the case of azo-SCLCPs, annealing in the dark at mesophase temperatures leads to an increasing of the birefringence (thermotropic effect). Nevertheless, the heating above the isotropization temperature as well as irradiation with circular polarized light erases the written information.

On the other hand, helical arrangements on macromolecules are recently object of intense research because of the scientific curiosity on nature-imitating macromolecules and their predicted technological applications2,3. In this sense, the control of heliticity arises as an aspect of crucial importance on the development of helical polymeric devices. Chiroptical properties on azopolymers have been usually induced by introduction of stereogenic centers on the macromolecular structure4,5. For these polymers, the prevailing chiral geometry of the chromophores along the macromolecular backbone determines the extent and handedness of the resulting supramolecular helicity. However, Nikolova et al. 6 have recently described the photoinduction of large circular anisotropy in films of an achiral mesogenic azopolyester on illumination with circularly polarized light (CPL) or amorphous polymers but illuminated with elliptically polarized light (EPL)7-

10. Furthermore, a reversible chiroptical switching has been described for these azopolymers11, which suppose a control of the photoinduced enantiomeric supramolecular structure in the material. Unusual effects are recently described on these materials as the switch of the sense of circular anisotropy during irradiation12, or the photofabrication of superhelix-like patterns using a conventional holographic optical set-up13.

We have synthesized different series of

polymers having a cianoazobenzene derivative as photoaddressable group for optical applications, such as holographic storage 14 or non linear optics15 . Some of these materials are gathered in Figure 1.

O-(CH2)n-O NN CN

CO

n= 2 PC2; n= 6 PC6; n= 10 PC10

O-(CH2)2-O NN CN

CO

O-(CH2)6-O NN OCH3

CO

0.5

0.5PC2/POMe-50

O-(CH2)6-O NN CN

CO

O-(CH2)6-OCO

0.1

0.9PC6/PBp-10

CN

Figure 1

In order to study in deep the relationship

between molecular structure, Tg and azo-content on the photoinduction of chirality, thin films of polymers shown in Figure 1 have been irradiated with circular polarized light and the chirooptical properties were examined by circular dichroism and polarimetry. The films were previously annealed at the mesophase temperature.

The CD spectra of these films are gathered in

Figure 2.

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00

2000

200 300 400 500 600Wavelength nm

Ellip

ticity

mde

g

PC2PC6PC10PC2/POMe-50PC6/PBf-10

62

Several conclusions can be drawn from these results. Firstly, there is an important effect of the length of the flexible spacer on the chiroptical properties. The hexamethylenic spacer provides an adequate flexibility to the polymer and a relatively high Tg, giving rise to a huge ellipticity. Secondly, the incorporation of a low percentage of azo groups on mesogenic copolymers can induce the organization of the non-photoaddressable, mesogenic side groups in a supramolecular chiral structure. Furthermore, the photoinduced supramolecular helix could be easily switched by irradiating with circular polarized light with opposite handness.

The proposed model for explaining this optical

behavior considers the polymeric films consisting of many layers. The presence of an optical axis in the first layer (intrinsically present on the liquid crystalline domains or induced by linear polarized light in amorphous materials) determines that CPL passing through the first layer is transmitted to the second layer as EPL. Consequently, molecules of the second layer reorient perpendicular to the long axis of the polarization ellipse and changes the azimuth of the polarization transmitted to the next layer. The overall effect is the formation of a supramolecular helical structure in which a cooperative effect is produced between light and mesogens in which a rotation of light is induced by mesogens as well as the light induced a rotation of mesogens.

Acknowledgements. The support from the CICYT under Project MAT2002-04118-C02 is gratefully acknowledged.

References 1 A. Natansohn, P. Rochon. Chem. Rev. 2002, 102, 4139. 2 M. Masuda, P. Jonkheijm, R. P. Sijbesma, E. W. Meijer. J. Am. Chem. Soc. 2003, 125, 15965. 3 J. H. K. K. Hirschberg, L. Brunsveld, A. Ramzi, J. A. J. M. Vekemans, R. P. Sijbesma, E. W. Meijer. Nature, 2000, 407, 167. 4 E. Yahima, J. Noguchi, Y. Okamoto. Macromolecules 1995, 28, 8368. 5 L. Angiolini, D. Caretii, L. Giorgini, E. Salatelli. Macromol. Chem. Phys 2000, 201, 533. 6 L. Nikolova, T. Todorov, M. Ivanov, F. Andruzzi, S. Hvilsted, P. S. Ramanujam. Opt. Mater. 1997, 8, 255. 7 L. Nikolova, L. Nedelchev, T. Todorov, T. Petrova, N. Tomova, Y. Dragostinova. App. Phys. Lett. 2000, 77, 657. 8 M. Ivanov, I. Naydenova, T. Todorov, L. Nikolova, T. Petrova, N. Tomova, V. Dragostinova. J. Mod. Opt. 2000, 47, 861. 9 L. Nedelchev, L. Nikolova, T. Todorov, T. Petrova, N. Tomova, V. Dragostinova, P. S. Ramanujam, S. Hvilsted. J. Opt. A: Pure Appl. Opt. 2001, 3, 304. 10 M. J. Kim, B. G. Shin, J. J. Kim, D. Y. Kim. J. Am. Chem. Soc. 2002, 124, 3504. 11 G. Iftime, F. Lagugné-Labarthet, A. Natansohn, P. Rochon. J. Am. Chem. Soc. 2002, 122, 12646. 12 D. K. Hore, A. Natansohn, P. J. Rochon. J. Phys. Chem. B 2003, 107, 2506. 13 M. J. Kim, J. Kumar, D. Y. Kim. Adv. Mater. 2003, 15, 2005.

14 C. Sánchez, R. Cases, R. Alcalá, A. López, M. Quintanilla, L. Oriol, M. Millaruelo. J. Appl. Phys. 2001, 89, 5299. 15 F. Rodríguez, J. Sánchez, B. Villacampa, R. Alcalá, R. Cases, M. Millaruelo, L. Oriol. Polymer 2004, 45, 2341.

63

CHIRAL HELICAL INDUCTION THROUGH H-BONDING IN SUPRAMOELCULAR POLYMERS

J. Barberá, L. Puig, J. L. Serrano, T. Sierra

The significant role of helical organizations in nature (i.e. α-helical proteins, nucleic acids, Tobacco Mosaic Virus) has stimulated the curiosity of researchers in materials chemistry. Many interesting examples aimed at building and controlling supramolecular chiral architectures based on helical superstructures have been reported 1,2. Indeed, interesting linear optical 3 and nonlinear optical properties 4, electrooptical behavior 5,6, energy transfer 7, etc. have been found in synthetic helical superstructures, which are often prepared according to the principles of supramolecular chemistry 8. We have developed an efficient strategy based on two types of non-covalent intermolecular interaction, i.e. π-π interactions and H-bonding, which have enabled the construction of a number of supramolecular liquid crystalline assemblies 9. Our approach consists on merging mesomorphic arrangements based on molecular stacking, promoted by π-π interactions of simple molecules, and the possibility of anchoring the structure of the mesophase using H-bonding interactions with a second type of molecule. In this way we should be able to build up stable helical polymeric assemblies in which chirality can be induced via a stereogenic center and transferred to the mesophase through hydrogen-bonding. The final supramolecular organization must be endowed of a one-dimensional helical arrangement along the column 10. For this purpose, we have chosen molecular units that are capable of organizing into columnar mesophases, by virtue of a disk-like promesogenic structure, and can also participate in intermolecular hydrogen-bonding interactions. We therefore decided to employ 2,4,6-triarylamino-1,3,5-triazines (figure 1a). It is also necessary to introduce chirality into the system and for this purpose we have selected R-3-methyladipic acid as a chiral clip (figure 1b). It was envisaged that this diacid would not only fix the supramolecular organization by building a polymeric-like structure but would also be able to imprint its chiral character onto the resulting self-assembled structure.

Figure 1. a) Molecular structure of the triazine derivative (peripheral tails are omitted for the sake of clarity) b) Molecular structure of (R)-3-methyladipic acid. c and d) Idealized cartoon representation of the structure for two supramolecular materials prepared with different proportions of (R)-3-methyladipic acid. The use of techniques such as x-ray diffraction and circular dichroism in the mesophase allow to confirm the success of the design. A reflection maximum corresponding to a periodic distance within the column appears in the x-ray diffraction patters of these supramolecular materials, especially those containing A regular stacking within the columns is, indeed, induced by the presence of R-3-methyladipic acid molecules fixing distances between disks by means of hydrogen bonding. Moreover, additional experiments with adipic acid have led to the conclusion that the methyl group in the stereogenic center of the R-(3)-methyladipic acid performs a twofold role in the supramolecular organization. Firstly, it must provide the acid a bent conformation that favors the possibility of interdisk association along the column, which helps to keep the columnar arrangement (figures 1b and 1c). Secondly, it is responsible of the transfer of chirality to a helical superstructure within the column, which is detected by circular dichroism experiments (figure 2). CD spectra recorded in the mesophase demonstrate that there is a formal optical activity due to a helical superstructure biased towards a chiral sense that is determined by the configuration of the stereogenic center. This optical activity disappears when the material reaches its transition temperature to the isotropic state.

Tri-2OC10/MeAdip [1:1] Tri-2OC10/MeAdip [2:1]

N

N

N

N

N

NH H

N

N

N

NHH

H

N

NH

*H OC

O

O

HOCH3

Tri-2OC10

MeAdip

a)b)

c) d)

64

Figure 2. CD spectral comparison of Tri-2OC10/MeAdip[2:1] in the isotropic liquid (80°C), in solution (10 mm cell, 2.5 x 10-5 M in hexanes) and in the mesphase, both in the freshly formed mesophase and after 24 h. The Uv spectrum in the region under study in the mesophase is shown below the corresponding CD spectrum. Acknowledgements Financial support was provided by MCyT (MAT2003-07806-C02-01) and DGA. References 1 N. Tamaoki. Adv. Mater. 2001, 13, 1135. 2 a) J. J. L. M. Cornelissen, A. E. Rowan, R. J. M. Nolte, N. A. J. M. Sommerdijk. Chem. Rev. 2001, 101, 4039. b) T. Nakano, Y. Okamoto. Chem. Rev. 2001, 101, 4013. 3 J. Lub, P. van de Witte, C. Doornkamp, J. P. A. Vogels, R. T. Wegh. Adv. Mater. 2003, 15, 1420. 4 a) T. Verbiest, S. van Elshocht, M. Kauranen, L. Hellemans, J. Snauwaert, C. Nuckolls, T. J. Katz, A. Persoons, Science, 1998, 282, 913. b) T. Verbiest, S. Sioncke, A. Persoons, L. Vyklicky, T. J. Katz. Angew. Chem. Int. Ed. 2002, 41, 3882. 5 C, Nuckolls, R. Shao, W,. G. Jang, D. M. Walba, T. J. Katz. Chem. Mater. 2002, 14, 773. 6 a) R. Iglesias, J. L. Serrano, T. Sierra, M. R. de la Fuente, B. Palacios, M. A. Pérez-Jubindo, J. T. Vázquez. J. Am. Chem. Soc. 1998, 120, 2908. b) J. L. Serrano, T. Sierra. Chem. Eur. J. 2000, 6, 759. 7 F. J. M. Hoeben, L. M. Herz, C. Daniel, P. Jonkheijm, A. P. H. J. Schenning, C. Silva, S. C. J. Meskers, D. Beljonne, R. T. Phillips, R. H. Friend, E. W. Meijer. Angew. Chem., Int. Ed. 1983, 22, 565. 8 J. M. Lehn. Principles of Supramolecular Chemistry 9 a) U. Beginn. Prog. Polym. Sci. 2003, 28, 1049. b) T. Kato, N. Mizoshita, K. Kanie. Macromol. Rapid. Commun. 2001, 22, 797. c) C. M. Paleos, D. Tsiourvas. Angew. Chem. Int. Ed. 1995, 34, 1696. 10 J. D. Hartgerink, E. R. Zubarev, S. I. Stupp. Curr. Opin. Solid. State Mater. Sci. 2001, 5, 355.

250 300 350 400 450λ (nm)

mesophase (25�C) after 24 h

2.5x10-5 in hexanesisotropic state (80�C)mesophase (25�C)

Inte

nsity

/ m

deg

Abs

.

-5

0

5

10

0,8-

0

Tri-2OC10/Adip [2:1]

65

NOVEL NLO-PHORES WITH PROAROMATIC DONOR AND ACCEPTOR GROUPS

R. Andreu, J. Garín, J. Orduna, R. Alcalá, B. Villacampa

Donor (D)–acceptor (A) substituted organic molecules with large second-order nonlinear optical (NLO) properties constitute a topic of burgeoning interest due to their possible applications in areas such as frequency doubling and photorefractive polymers, among others. These molecules can show large first molecular hyperpolarizabilities (β), related to an electronic intramolecular charge transfer excitation between the ground and excited states of the molecule, and it has long been recognized that D-π-A NLO-phores with dominantly aromatic ground state do not favor electronic polarization in an applied field, as a result of the decreased resonance energy upon charge transfer. This led Marder et al. to design D-π-A systems in which the loss of aromaticity in one end (D) on charge separation was offset by a gain in aromaticity in the opposite end (A) 1. Given the success of this approach to obtain NLO-phores with high β values, a great deal of effort has been devoted to the study of derivatives bearing proaromatic acceptors.

In this work we report the first systematic experimental and theoretical study of the second-order NLO properties of merocyanines incorporating both a proaromatic donor and a proaromatic acceptor.

The target merocyanines incorporating an acyclic spacer (3, 5a and 5b) were prepared by reaction of 1 with dithiolium salt 2 or aldehydes 4a and 4b, respectively (Scheme 1).

Since the instability of some push-pull polyenes is a well-known issue, we reasoned that incorporation of a partially rigidified spacer could increase the stability of the desired NLO-phores. In fact, reaction of compound 6 with 4a and 4c afforded 9a and 9c, with four and six double bonds in the spacer, respectively. Moreover, compound 8, directly analogous to 5b, was prepared (by reaction of 6 with salt 7) with a view to study the effect of the introduction of the cyclohexene moiety on the linear and nonlinear optical properties of these NLO-phores.

Relevant electrochemical and optical characterization data are gathered in Table 1. Cyclovoltammetric data indicate that oxidation of the dithiafulvene moiety and reduction of the thiobarbituric unit (both chemically irreversible processes) become increasingly easier on lengthening the π-spacer, indicating a smaller contribution of the charge-separated form to the ground state of the longer derivatives.

The second-order NLO properties of the NLO-phores were determined by EFISH. The measured µβ0 values, determined using the two-level model, range from – 9×10-48 esu for 3 to 1350×10-48 esu for 9c.

SS

SMe2

I

NN

O

OS

Et

Et SSMe

Me O

MeMe

Me

NN

O

OS

Et

Et

SS

SMeMe

Me

BF4

7

6

MeMe NN

O

OS

Et

Et

SSMe

Me

MeMe NN

O

OS

Et

Et

SS

Me

Me

NN

O

OS

Et

Et

SS

8

SSMe

Me NN

O

OS

Et

Et

NaOEt, EtOH ∆

n

4a, 4b, (4c)

EtOH, ∆n

1

3

5a, 5b

n

NEt3, pyridine ∆

4a, 4cpiperidine (cat.)

toluene ∆

9a, 9ca: n = 1; b: n = 2; c: n = 3

Scheme 1. Synthetic approach

Table 1. Redox Potentials (V), Absorption Spectra (nm) and µβ (10–48 esu) for CH2Cl2 Solutions

compound Eoxa Ered

a λmax µβb µβ0c

3 1.55 –1.48 403 –12 –9

5a 1.16 –1.00 558 100 60

5b 0.87 –0.85 642 1100 525

8 0.81 –0.96 630 440 221

9a 0.65 –0.81 638 2315 1135

9c 0.48 –0.77 638 2746 1350

a vs Ag/AgCl, glassy carbon working electrode, 0.1 M TBAPF6, 0.1 V s-1 b Measured at 1907 nm c Calculated using the two-level model.

Inspection of Table 1 reveals that, for the

same type of spacer, µβ0 values increase with the conjugation path, and that introduction of the isophorone-derived bridge gives rise to a decrease of µβ0 when compared to an acyclic spacer of the same conjugation length (5b and 8). It should be noted that µβ0 for 9c is about four times larger than for DANS (4,-dimethylamino-4’-nitrostilbene), a common benchmark for second-order NLO-phores.

66

Moreover, compound 3 is the only one to show a small but negative value.

Ab initio and DFT calculations have been carried out on model compounds 10 (Figure 1) in order to disclose the role of the proaromaticity of the end groups on the properties of these NLO-phores.

SS

NN

O

OS

H

Hn

10

a: n = 0b: n = 1c: n = 2d: n = 3

Figure 1. Theoretically studied compounds. The most relevant results of the calculations

are gathered in Table 2.

Table 2. Calculated BLA (Å), Charge on the Dithiole Ring (e) and µβ0 (10–48 esu) for Model Compounds 10.

compound BLAa chargeb µβ0 (calc)b

10a –– +0.344 –62

10b –0.029 +0.207 2

10c –0.040 +0.129 437

10d –0.043 +0.086 1363

a B3P86/6-31G* b HF/6-31G*//B3P86/6-31G*

It can be seen that lengthening the π-spacer

results in an increase of ⏐BLA⏐, together with a decrease of the charge on the dithiole ring. This implies that the gain in aromaticity at the end groups and the contribution of the zwitterionic limiting form to the ground state of these molecules are more important for the shorter derivatives. This is confirmed by the small negative µβ0 value displayed by compound 3, implying that µg > µe (where g and e refer to the ground and excited states, respectively). Its very weak solvatochromism also suggests that this molecule is close to the cyanine limit and that, therefore, lies in region C, according to Marder’s classification.

Although CPHF calculations correctly reproduce the observed trend in the µβ0 values of these NLO-phores, a more intuitive picture of their NLO properties comes from the two-level model. In this simplified treatment β ∝ ∆µ×fge/E3, where ∆µ = µe–µg, and fge and E are the oscillator strength and the energy of the intramolecular charge transfer transition, respectively. On passing from 10a to 10d, TD-DFT calculations show an increase in fge and a decrease in E but, more important, predict a smooth increase in µg and a steeper increase in µe. Therefore, ∆µ rapidly increases along this series and, being negative for 10a, an inversion in the sign of ∆µ is calculated to occur near 10b (Figure 2).

0

5

10

15

20

25

0 1 2 3

µg

µe

Dip

ole

mom

ent (

D)

n Figure 2. Calculated µg and µe values for 10.

This explains the low µβ values calculated

for some dithiole-π-acceptor NLO-phores incorporating two C=C bonds (n = 1) in the spacer, a fact that cannot be attributed to a poor electron-donating ability of the 1,3-dithiole unit. A comparison of the optical properties of the 1,3-dithiole NLO-phores herein reported with those of the TTF-thiobarbituric series reveals that: a) lengthening the π spacer in the former series results in a bathochromic shift, in sharp contrast to the unusual hypsochromic shift observed with the TTF derivatives 2, and b) the 4,5-dimethyl-1,3-dithiole unit is a more efficient donor than the TTF moiety for a given number of conjugated atoms.

To sum up, the proaromatic character of the 1,3-dithiole group gives rise to high µβ values, provided long spacers are used; lengthening the polyenic chain results in large photoinduced changes in the dipole moment and enhanced hyperpolarizabilities. The negative µβ value for the shortest derivative demonstrates the importance of the zwitterionic form in the description of its ground state. Experimental and theoretical results demonstrate that the 1,3-dithiole moiety is a more efficient π electron-donor than TTF in dipolar D–π–A NLO-phores.

Principal publication R. Andreu, J. Garín, J. Orduna, R. Alcalá, B. Villacampa. Org. Lett. 2003, 5, 3143.

Acknowledgements MCyT-FEDER (BQU2002-00219) and Gobierno de Aragón-Fondo Social Europeo (P009-2001 and E39).

References 1 S. R. Marder, B. Kippelen, A. K. Y. Jen, N. Peyghambarian. Nature 1997, 388, 845. 2 M. González, J. L. Segura, C. Seoane, N. Martín, J. Garín, J. Orduna, R. Alcalá, B. Villacampa, V. Hernández, J. T. López Navarrete. J. Org. Chem. 2001, 66, 8872.

67

THE CRYOGENIC CURRENT COMPARATOR, DESIGN TOOLS FOR AN ULTIMATE PRECISION INSTRUMENT

J. Sesé, A. Camón, C. Rillo

The Cryogenic Current Comparator (CCC)

takes advantage of the ideal properties of superconductors to perform ultimate precision measurements in electrical metrology. On one hand the Meissner effect provides a perfect magnetic shielding (see fig. 1). On the other hand the Josephson effects provide with a very sensitive device, the SQUID, for the measurement of currents in the pA range.

Figure 1: Simulation used finite element software that shows how a superconducting enclosure provides a perfect shield for the magnetic field created by a current circulating in the overlapping tube.

The CCC (see fig. 2) allows controlling the

ratio of two currents I1/I2=N2/N1 (where N1 and N2 are integer numbers) with high precision. Resistance bridges based on the CCC are the state of the art to perform dc resistance comparisons at metrological level. They are at present widely used to transfer the value of the quantum Hall resistance standard to very stable resistors 1. More recently, its use for the accurate amplification of quantized currents, in the pA range, produced by Single Electron Tunneling devices, towards the realization of a quantum current standard, is being investigated 2-4.

First designs were introduced in the 1970s 2

and it has later been used in national metrology laboratories around the world. Its application for the current standard needs to take the instrument to its limits. Yet, formal guidelines and analytical tools for the design and of CCCs were not developed. Therefore the goal at ICMA was to develop these tools.

Figure 2: General view of a CCC

Figure 3 shows the model that takes into account all shielding effects produced by

superconductors. Hence the self-inductances are effective values different from their nominal values.

Figure 3: Schematic representation of a CCC coupled to a SQUID through a superconducting flux transformer.

Based on this model, analytical tools have

been developed that permit the design of an optimum CCC. These tools have been checked with the realization of experiments finding a good agreement (see fig. 3), even more they have allowed to discard previous theoretical work found in the literature 6.

Figure 3: Sensitivity data (circles) obtained from [6], for

CCCs with tape pick-up coils. The data (filled squares) and the numerical calculation (dashed line) for coil #2 are shown together with the result, using superconducting tape (filled triangle) instead of wire.

Principal publications C. Rillo, J. Sesé, E. Bartolomé, A. Camón, J. Flokstra, G. Rietveld. Metrologia 2003, 40, 51. J. Sesé, E. Bartolomé, A. Camón, J. Flokstra, G. Rietveld, C. Rillo. IEEE T. Instrum. Meas. 2003, 52, 612. Acknowledgements Work supported by projects CICYT MAT98-0668 and STW (The Netherlands). References 1 B. Jeckelmann, B. Jeanneret. Rep. Prog. Phys. 2001, 64, 1603. 2 A. Hartland. Conf. Electrom. Meas. BEMC, 1993, 18, 1. 3 Y. de Wilde, F. Gay, F. Piquemal, G. Geneves. IEEE T. Instrum. Meas. 2001, 50, 231. 4 E. Bartolomé. Ph. D. Thesis, University of Twente, The Netherlands, 2002. 5 I. K. Harvey. Rev. Sci. Instrum. 1972, 43, 1626. 6 E. T. Frantsuz. Metrologia 1998, 35, 847.

69

1.- Estructura del Instituto Structure of the Institute

71

1.1.- Organigrama Organizational Chart

DEPARTAMENTOS DE INVESTIGACIÓN

ÁREA QUÍMICAS

Espectroscopia de Sólidos

Física del Estado Sólido a Bajas Temperaturas

Magnetismo de Sólidos

Materiales de Interés

Tecnológico

Nuevos Materiales Orgánicos

Teoría y simulación de sistemas complejos

DIRECTOR

CLAUSTO CIENTIFICO

JUNTA INSTITUTO

GERENCIA

VICEDIRECTOR ÁREA QUÍMICAS

VICEDIRECTOR ÁREA MATERIALES

SERVICIOS

DEPARTAMENTOS DE INVESTIGACIÓN ÁREA MATERIALES

Química de los Compuestos

Organometálicos

Química de la Coordinación y Catálisis Homogénea

Química Orgánica

Oficina técnica

RMN

Espectrometría de masas

Análisis térmico

Microanálisis

Servicios Económicos

Administrativos

72

1.2.- Dirección

Administration - Año 2002 / Year 2002:

∗ Director / Director: Gascón Alonso, Pablo Javier ∗ Vicedirectores / Deputy Directors: Carmona Gascón, Daniel

Lázaro Osoro, Francisco ∗ Gerente / Administrator: Miguel Pardo, Mª Elisa de

- Año 2003 / Year 2003:

∗ Director / Director: Burriel Lahoz, Ramón ∗ Vicedirectores / Deputy Directors: Cativiela Marín, Carlos Angurel Lambán, Luis Alberto ∗ Gerente / Administrator: Miguel Pardo, Mª Elisa de

1.3.- Junta

Institute Council * Presidente / President: Burriel Lahoz, Ramón * Secretaria / Secretary: Miguel Pardo, Mª Elisa de * Vocales / Council Members: Cativiela Marín, Carlos Angurel Lambán, Luis Alberto Falvello, Lawrence Rocco (Jefe Dpto.) Tejel Altarriba, Mª Cristina (Jefe Dpto.) Tejero López, Tomás (Jefe Dpto.) Orera Clemente, Víctor (Jefe Dpto.) Rillo Millán, Conrado (Jefe Dpto.) Algarabel Lafuente, Pedro A. (Jefe Dpto.) Fuente Leis, Germán Francisco de la (Jefe Dpto.) Ros Latienda, Blanca (Jefe Dpto.) Falo Forniés, Fernando (Jefe Dpto.) Estepa Millán, Luis Carlos (Rpte. Personal Técnico Tit.) Jiménez Sanz, Ana (Rpte. Bec. y Pers. Doc. no Perm.) Serrate Donoso, David (Rpte. Bec. y Pers. Doc. no Perm.) Martínez Martínez, Jesús I. (Rpte. Pers. Cient. UZ)

73

1.4.- Claustro Científico Scientific Board

∗ Presidente / President: Burriel Lahoz, Ramón ∗ Secretaria / Secretary: Miguel Pardo, Mª Elisa de

Alcalá Aranda, Rafael Algarabel Lafuente, Pedro A. Alonso Gascón, Pablo Javier Andreu Solano, Raquel Angurel Lambán, Luis A. Ara Laplana, Irene V. Arnaudas Pontaque, José I. Arrate Martínez, Mónica Artigas Álava, Miguel Badía Majós, Antonio Barberá Gracia, Joaquín Bardají Luna, Manuel Bartolomé Sanjoaquín, Juan Bartolomé Usieto, Fernando Baselga Arino, Santiago Blasco Carral, Javier Buil Juan, Mª Luisa Burriel Lahoz, Ramón Camón Lasheras, Agustín Campo Ruíz, José Javier Carmona Gascón, Daniel Casado Lacabra, Miguel Ángel Casas del Pozo, José Mª Cases Andreu, Rafael Castejón Herrer, Luis Castro Corella, Miguel Cativiela Marín, Carlos Cerrada Lamuela, Elena Chaboy Nalda, Jesús Ciria Cosculluela, José C. Ciria Remacha, Miguel Ciriano López, Miguel Ángel Contel Fernández, María Crespo Zaragoza, Olga Díaz de Villegas Soláns, Mª Dolores Díez Moñux, Juan Carlos Elduque Palomo, Ana Isabel Esteban Pérez, Montserrat Esteruelas Rodrigo, Miguel Ángel Falo Forniés, Fernando Falvello, Lawrence R. Fernández Álvarez, Francisco J. Fernández Novoa, Julio F. Ferrer Cerra, Joaquina Floría Peralta, Mario Forniés Gracia, Juan Fortuño Turmo, Consuelo Fraile Dolado, José María Franco Ontaneda, Santiago Fuente del Rey, César de la Fuente Leis, Germán de la Gálvez Lafuente, José Antonio García Clemente, Mª Pilar García Landa, Berta García Laureiro, José Ignacio García Palacios, José Luis García Ruíz, Joaquín García Vinuesa, Luis Miguel Garín Tercero, Javier

Giménez Soro, Raquel Gimeno Floría, Mª Concepción Ibarra García, Ricardo Jiménez Rupérez, Mª Victoria Jiménez Sanz, Ana Isabel Jiménez Villar, Josefina Laguna Castrillo, Antonio Laguna Castrillo, Mariano Laguna Gómez, Mª Ángeles Lahoz Díaz, Fernando José Lamata Cristóbal, Mª Pilar Larrea Arbáizar, Ángel Larrodé Pellicer, Emilio Lázaro Osoro, Francisco José Lera García, Francisco López Calvo, José Antonio López de Lama, Ana Margarita López Ram de Viú, Mª Pilar Luis Vitalla, Fernando Lydon, Donocadh Patrick Marcos Martínez, Mercedes Marquina García, Clara Isabel Martín Casado, Marta Martín Moreno, Luis Martín Tello, Antonio Jesús Martínez Buenaga, Francisco Martínez Fernández, Elena Martínez Martínez, Jesús Ignacio Martínez Ovejas, Pedro Mayoral Murillo, José Antonio Mazo Torres, Juan José Melero Estela, Julio Menjón Ruíz, Babil Merchán Álvarez, Francisco L. Merino Filella, Pedro Merino Rubio, Rosa Isabel Millán Escolano, Ángel Miravete de Marco, Antonio Modrego Pérez, Francisco Javier Mora Alfonso, Mario Moral Gámiz, Agustín del Morellón Alquézar, Luis Morón Lafuente, Mª Carmen Navarro Gómez, Fernando Navarro Linares, Rafael Navarro Martín, Rafael Oliete Terraz, Patricia Beatríz Oliván Escó, Montserrat Omenat Val, Ana Carmen Oñate Rodríguez, Enrique Orduna Catalán, Jesús Orera Clemente, Víctor Manuel Oriol Langa, Luis Oro Giral, Luis Antonio Palacio Parada, Fernando Palacios Latasa, Elías Peña Torre, José Ignacio Pérez Torrente, Jesús J. Piñol Lacambra, Milagros

74

Pires Ezquerra, Elisabet Proietti, Maria Grazia Puértolas Ráfales, José Antonio Rillo Millán, Conrado Rojo Martínez, José Antonio Romero Soria, Pilar Ros Latienda, Blanca Royo Cantabrana, Eva Rubín Llera, Javier Rueff, Jean Michel Salvatella Ibáñez, Luis Sánchez Sierra, Mª Concepción Sanjuán Álvarez, Mª Luisa Savirón Sánchez, María Serrano Ostáriz, José Luis Sicilia Martínez, Violeta Sierra Travieso, Teresa Sola Larraya, Eduardo Sotelo Mieg, Andrés Emilio Stankiewicz, Jolanta Tahir, Rachid Tejel Altarriba, Mª Cristina Tejero López, Tomás Teresa Nogueras, José Mª de Tomás Lisbona, Milagros Uriel Rubio, Santiago Urriolabeitia Arrondo, Esteban Pablo Usón Finkenzeller, Miguel Ángel Viguri Rojo, Fernando Villacampa Naverac, Belén Villacampa Pérez, Mª Dolores Villarroya Aparicio, Beatríz Eva

75

1.4.- Departamentos de Investigación

Research Departments Ciencia y Tecnologías Químicas Chemistry: Science and Technology Química de los Compuestos Organometálicos Organometallic Chemistry ● Personal científico permanente / Scientific staff

− Ara Laplana, Irene V. Prof. Titular − Casas del Pozo, José Mª Prof. Titular − Falvello, Lawrence Rocco Prof. Asociado Permanente (Categoria Catedrático) − Forniés Gracia, Juan Catedrático − Fortuño Turmo, Consuelo Prof. Titular Esc. Univ. − Gimeno Floría, Mª Concepción Investigador Científico − Jiménez Villar, Josefina Prof. Titular Esc. Univ. − Laguna Castrillo, Mariano Prof. de Investigación − Laguna Castrillo, Antonio Catedrático − Martín Tello, Antonio Jesús Científico Titular − Martínez Buenaga, Francisco Prof. Titular − Menjón Ruiz, Babil Científico Titular − Navarro Martín, Rafael Catedrático − Sicilia Martínez, Violeta Prof. Titular Esc. Univ. − Tomás Lisbona, Milagros Investigador Científico − Urriolabeitia Arrondo, Esteban Científico Titular − Usón Finkenzeller, Miguel A. Prof. Titular − Villacampa Pérez, Mª Dolores Prof. Titular

● Personal científico contratado y becarios / Contract scientists and Ph.D. students

− Bielsa Sebio, Raquel Becario − Cerrada Lamuela, Elena Prof. Asociado − Contel Fernández, María Investigador Contratado − Crespo Zaragoza, Olga Prof. Asociado − Chacuche, Naima Becario − Diosdado Cabrera, Beatriz Becario − Escorihuela Vitales, Inmaculada Becario − García Monforte, María Ángeles Becario − Jones, Lathe Becario − Lardiés Miazza, Nora Becario − Larraz Duaso, Carmen Becario − Luquín Martínez, Mª Asunción Becario − Martín Julián, Francisco Becario − Sanz Calvo, Sergio Becario − Soler García, Tatiana Becario

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Química de la Coordinación y Catálisis Homogénea Coordination Chemistry and Homogeneous Catalysis ● Personal científico permanente / Scientific staff

− Carmona Gascón, Daniel Prof. de Investigación − Ciriano López, Miguel Ángel Prof. de Investigación − Elduque Palomo, Ana Isabel Prof. Titular − Esteban Pérez, Montserrat Catedrática Esc. Univer. − Esteruelas Rodrigo, Miguel A. Catedrático − Ferrer Cerra, Joaquina Prof. Titular Esc. Univ. − García Clemente, Mª Pilar Prof. Titular − Jiménez Rupérez, Mª Victoria Científico Titular − Lahoz Díaz, Fernando José Investigador Científico − Lamata Cristóbal, Mª Pilar Prof. Titular Esc. Univ. − López Calvo, José Antonio Prof. Titular − López de Lama, Ana Margarita Prof. Titular Esc. Univ. − Modrego Pérez, Francisco J. Prof. Titular − Oro Giral, Luis Antonio Catedrático − Pérez Torrente, Jesús J. Prof. Titular − Sola Larraya, Eduardo Científico Titular − Tejel Altarriba, Mª Cristina Investigador Científico − Viguri Rojo, Fernando Prof. Titular Esc. Univ. − Villarroya Aparicio, Beatríz Eva Prof. Titular


− Acosta Martínez, Ana Becario − Asensio Fletas, Adriana Becario − Barrio Sena, Mª Pilar Becario − Bolaño García, Tamara Becario − Buil Juan, Mª Luisa Contr. "Ramón y Cajal" − Camerano Chirón, José A. Becario − Casado Lacabra, Miguel Á. Contr. "Ramón y Cajal" − Castarlenas Chela, Ricardo Contratado "I3P" Doctor − Eguillor Armendáriz, Beatríz Becario − Fabra Caro, María José Becario − Fernández Álvarez, Frco. J. Investigador Contratado − García Camprubí, Alba Becario − García Villalta, Néstor Becario − González Marín, Ana Isabel Investigador Contratado − Hernández Rojas, Yohar Becario − Jiménez Franco, Sonia Becario − Martín Casado, Marta Contr. "Ramón y Cajal" − Mateo Pérez, A. Concepción Becario − Oliván Esco, Montserrat Contr. "Ramón y Cajal" − Oñate Rodríguez, Enrique Prof. Asociado − Rodríguez Martínez, Ricardo Becario − Royo Cantabrana, Eva Prof. Asociado − Tajada Serrano, Mª Ángeles Investigador Contratado − Tejero Artigas, Santiago Becario − Todorova Dobrinovitch, Isabel Becario − Torres Blasco, Olga Becario

● Personal Técnico / Technical personnel

− Martín Albina, Mª Luisa Contratado "I3P" Técnico − Plou Lafuente, Pablo Técnico Superior

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Química Orgánica Organic Chemistry ● Personal científico permanente / Scientific staff

− Cativiela Marín, Carlos Catedrático − Díaz de Villegas Soláns, Mª Dolores Investigador Científico − Fraile Dolado, José María Científico Titular − Franco Ontaneda, Santiago Prof. Titular − Gálvez Lafuente, José Antonio Prof. Titular − García Laureiro, José Ignacio Investigador Científico − López Ram de Viu, Mª Pilar Prof. Titular − Mayoral Murillo, José Antonio Prof. Titular − Merchán Alvarez, Francisco L. Prof. Titular − Merino Filella, Pedro Prof. Titular − Pires Ezquerra, Elisabet Prof. Titular Esc. Univ. − Salvatella Ibáñez, Luis Prof. Titular − Tejero López, Tomás Prof. Titular


− Aguirre Ardanaz, Daniel Becario − Alias Niño, Miriam Prof. Asociado − Badorrey Miguel, Ramón Ángel Prof. Ayudante − Ballano Ballano, Gema Becario − Casabona Agudo, Diego Becario − Díez Gracia, Roberto Becario − Etayo Pérez, Pablo Becario − Gil Ferrás, Ana Becario − Herrerías Larripa, Clara Prof. Ayudante − Jiménez Sanz, Ana Isabel Contr. “Ramón y Cajal” − Lafuente Aranda, Gustavo Contratado − Lasa Ventura, Marta Becario − Matés Valdivieso, Juan Antonio Becario − Royo Gracia, Soledad Becario − Solanas Díaz, Mª Concepción Becario − Vanni, Mannucci Becario − Villalba Bayo, Isabel Investigador Contratado

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Ciencia y Tecnología de Materiales Materials Science and Technology Espectroscopía de Sólidos Spectroscopy of Solids ● Personal científico permanente / Scientific staff

− Alcalá Aranda, Rafael Catedrático − Alonso Gascón, Pablo Javier Prof. de Investigación − Cases Andreu, Rafael Prof. Titular − Martínez Martínez, Jesús Ignacio Prof. Titular − Merino Rubio, Rosa Isabel Científico Titular − Orera Clemente, Víctor Manuel Prof. de Investigación − Sanjuán Álvarez, Mª Luisa Científico Titular - Villacampa Naverac, Belén Prof. Titular


− Alonso Gutiérrez, Pablo Becario − Laguna Bercero, Miguel Ángel Becario − Rodríguez Martínez, F. Javier Becario − Sánchez Somolinos, Carlos Contratado "I3P" Doctor

● Personal técnico / Technical personnel

− Gotor Montañés, Rubén Técnico Contratado − Laguna Gómez, María Ángeles Técnico Superior

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Física del Estado Sólido a Bajas Temperaturas Low Temperature Solid State Physics ● Personal científico permanente / Scientific staff

− Artigas Alava, Miguel Prof. Titular − Bartolomé Usieto, Fernando Científico Titular − Bartolomé Sanjoaquín, Juan Prof. de Investigación − Blasco Carral, Javier Científico Titular − Burriel Lahoz, Ramón Prof. de Investigación − Camón Lasheras, Agustín Científico Titular − Castro Corella, Miguel Prof. Titular − Chaboy Nalda, Jesús Científico Titular − Fernández Novoa, Julio F. Científico Titular − García Ruíz, Joaquín Prof. de Investigación − García Vinuesa, Luis Miguel Prof. Titular − Proietti Cecconi, Mª Grazia Prof. Titular − Luis Vitalla, Fernando Científico Titular − Morón Lafuente, Mª Carmen Científico Titular − Palacio Parada, Fernando Prof. de Investigación − Palacios Latasa, Elías Prof. Titular − Rillo Millán, Conrado Prof. de investigación − Rubín Llera, Javier Prof. Titular


− Campo Ruiz, José Javier Contr. "Ramón y Cajal" − Herrero Martín, Javier Becario − Herrero Albillos, Julia Becario − Laguna Marco, Mª Ángeles Becario − López Ruiz, Román Becario − Millán Escolano, Ángel Científico Titular (c.s.) − Piquer Oliet, Cristina Cont. "Ramón y Cajal" − Plugaru, Neculai Investigador Contratado − Rodríguez Velamazán, José Alberto Becario − Stankiewicz Ciepielewska, Jolanta Contr. "Ramón y Cajal" − Subías Peruga, Gloria Contr. "Ramón y Cajal" − Tocado Martínez, Leticia Becario


− Gil Andaluz, Miguel Ángel Técnico Contratado − Sánchez Sierra, Mª Concepción Técnico Superior

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Magnetismo de Sólidos Magnetism of Solids ● Personal científico permanente / Scientific staff

− Algarabel Lafuente, Pedro A. Prof. de Investigación − Arnaudas Pontaque, José Ignacio Prof. Titular − Fuente del Rey, César de la Prof. Titular − Ibarra García, M. Ricardo Catedrático − Marquina García, Clara Isabel Científico Titular − Moral Gámiz, Agustín del Catedrático − Morellón Alquézar, Luis Prof. Titular − Teresa Nogueras, José María de Científico Titular


− Benito Ruiz, Luis Pablo Becario − Ciria Remacha, Miguel Contr. "Ramón y Cajal" − Mágen Domínguez, César Becario − Serrate Donoso, David Becario − Sikora, Marcin Andrzej Contratado − Zajac, Dariusz Andrzej Contratado


− Martín Sacristán, Carlos Técnico Superior

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Materiales de Interés Tecnológico Technological Materials ● Personal científico permanente / Scientific staff

− Angurel Lambán, Luis Alberto Prof. Titular − Díez Moñux, Juan Carlos Prof. Titular − Fuente Leis, Germán de la Investigador Científico − Larrea Arbáizar, Angel Científico Titular − Lázaro Osoro, Francisco José Prof. Titular − Lera García, Francisco Prof. Titular − Miravete de Marco, Antonio Catedrático − Navarro Linares, Rafael Catedrático − Peña Torre, José Ignacio Prof. Titular − Puértolas Ráfales, José Antonio Catedrático − Rojo Martínez, José Antonio Prof. Titular


− Carrera Alegre, Marco Antonio Contratado − Caudevilla Portero, Hortensia Prof. Asociado − Cuartero Salafranca, Jesús Prof. Asociado − Francisco García, Isabel de Becario − Gimeno Bellver, Fernando José Becario − Guzmán de Villoria L., Roberto Becario − Korrany Hassan, Mohamed Becario − Lahoz Espinosa, Ruth Contratado − Lennikov, Vassili Becario − López Gascón, Clara Isabel Becario − Martínez Fernández, Elena Contratado ”I3P” Doctor − Mora Alfonso, Mario Prof. Asociado − Oliete Terraz, Patricia Beatriz Prof. Asociado − Ranz Angulo, David Becario − Sotelo Mieg, Andrés Emilio Prof. Asociado − Vargas Silva, Gustavo Adolfo Becario


− García Garcés, Miguel Prof. Asociado − Gómez García, José Antonio Contratado

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Nuevos Materiales Orgánicos New Organic Materials ● Personal científico permanente / Scientific staff

− Andreu Solano, Raquel Prof. Titular − Barberá Gracia, Joaquín Prof. Titular − Garín Tercero, Javier Prof. Titular − Marcos Martínez, Mercedes Investigador Científico − Navarro Gómez, Fernando Prof. Titular Esc. Univ. − Omenat Val, Ana Carmen Científico Titular − Orduna Catalán, Jesús Científico Titular − Oriol Langa, Luis Prof. Titular − Piñol Lacambra, Milagros Prof. Titular Esc. Univ. − Ros Latienda, Blanca Prof. Titular − Serrano Ostáriz, José Luis Catedrático − Sierra Travieso, Teresa Científico Titular


− Carrasquer Lozano, Laura Becario − Cavero Menéndez, Emma Becario − Forcén Jiménez, María Patricia Becario − Giménez Soro, Raquel Prof. Ayudante − Gimeno Gomaz, Nélida Becario − López Herranz, Carolina Becario − Martín Rapún, Rafael Becario − McKenna, Mark Becario − Piñol Lacambra, Rafael Becario − Puig Fernández, Laura Becario − Silvino Chinelatto, Luiz Becario − Tejedor Bielsa, Rosa Prof. Asociado − Uriel Rubio, Santiago Prof. Asociado − Viñuales Martínez, Ana Isabel Becario

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Teoría y Simulación de Sistemas Complejos Theory and Simulation of Complex Systems ● Personal científico permanente / Scientific staff

− Badía Majós, Antonio Prof. Titular − Falo Forniés, Fernando Prof. Titular − Floría Peralta, Mario Prof. Titular − Martín Moreno, Luis Prof. Titular − Martínez Ovejas, Pedro Prof. Titular Esc. Univ. − Mazo Torres, Juan José Prof. Titular


− Cuesta López, Santiago Becario − García Palacios, José Luis Contr. "Ramón y Cajal" − Gómez Gardeñes, Jesús Becario − López-Tejeira Sagüés, Fernando Contratado − Zueco Láinez, David Becario

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1.5.- Unidades de Apoyo Support Services

Administración y Gerencia Secretary and Administrator

− Arasanz Lanau, Mª Concepción Administrativo − Elías Martínez, Mª Isabel Auxiliar Administrativo − Marco Pérez, Concepción Auxiliar Administrativo − Miguel Pardo, Mª Elisa de Técnico de Gestión

Personal Técnico Technical Personnel ● Servicios generales Technical services

− Estepa Millán, Luis Carlos Titulado Técnico Especializado − García Casanova, Rosa Titulado Técnico Especializado − Nieto Méndez, Yolanda Contratado "I3P" Técnico − Romero Soria, Mª Pilar Titulado Superior

● Apoyo a departamentos Departmental support staff

− Bernad Pérez, Ana Lidia Ayudante de Investigación − Francisco Tomás, Carmen de Ayudante de Investigación − Martínez Ruiz, Marisol Ayudante de Investigación − Mayoral Asensio, Isabel Titulado Técnico Especializado − Sauras Fernández, Francisco Ayudante de Investigación

Servicios Generales Technical Services

• Oficina técnica / Technical office • Espectrometría de masas / Mass spectrometry • Resonancia magnética nuclear / Nuclear magnetic resonance • Análisis térmico / Thermal analysis

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OFICINA TÉCNICA / TECHNICAL OFFICE

Diseño y fabricación de equipos científicos e infraestructura para la investigación Design and fabrication of research equipment and infrastructure for research

Máquina de desgaste para UHPM

Wearing machine for UHPM Palabras clave: Infraestructura para investigación, diseño y construcción de prototipos, modificación y mejora de sistemas, adquisición de equipamiento. Descripción: Infraestructura general de laboratorios de materiales. Hornos. Cámaras de tratamiento de materiales. Sistemas de movimiento. Prensado isostático y axial. Útiles para la investigación. Adquisición de láseres industriales y sus sistemas complementarios. Apoyo y participación en los proyectos de carácter técnico y aplicado del ICMA. Persona de contacto: Responsable del Servicio: Carlos Estepa ([email protected]).

Ubicación: Centro Politécnico Superior. Edificio Torres Quevedo. María de Luna, 3. 50018 Zaragoza. Tel.: 976 762523.

Conjunto óptico para división de haz láser

Optical bench for laser beam splitting

Keywords: Research infrastructure, prototype design and construction, systems improvement, new equipment support. Description: General infrastructure for materials laboratories. Furnaces. Materials processing chambers. Translational systems. Isostatic and axial presses. Research equipment. Support for industrial laser and complementary systems acquisitions. Support for technical projects at ICMA. Contact person: Head Engineer: Carlos Estepa ([email protected])

Address: Centro Politécnico Superior. Edificio Torres Quevedo. María de Luna, 3. 50018 Zaragoza. Tel.: 976 762523.

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ESPECTROMETRÍA DE MASAS / MASS SPECTROMETRY

Palabras clave: Espectrometría de Masas. Descripción del equipo: Autoespec VG (Actualmente Waters) Técnicas e instrumentación disponibles: Analizador magnético trisector EBE, de alta resolución. Sistemas de Introducción directa de muestras y cromatografía de gases. Sistemas de Ionización: EI+ , CI+, CI-, FAB+, FAB-. Personas de contacto: Jefe del Servicio: Dr. Mariano Laguna ([email protected]). Responsable del Servicio: Dr. Jesús Orduna ([email protected]). Titulado Técnico: Rosa M. García ([email protected]). Ubicación: Facultad de Ciencias, Edificio A, Pedro Cerbuna, 12. 50009 Zaragoza. Tel.: 976 761181/1194/3313).

Keywords: Mass spectrometry. Equipment: VG Autospec (Waters). Available techniques: EBE trisector high resolution analyzer. Autosampler and gas chromatography. Ionization systems: EI+ , CI+, CI-, FAB+, FAB-. Contacts: Head of the Service: Dr. Mariano Laguna ([email protected]). Scientist in charge: Dr. Jesús Orduna ([email protected]). Technical personnel: Rosa M. García ([email protected]).

Address: Facultad de Ciencias, Edificio A, Pedro Cerbuna, 12. 50009 Zaragoza. Tel.: 976 761181/1194/3313.

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ESPECTROSCOPIA DE RESONANCIA MAGNÉTICA NUCLEAR NUCLEAR MAGNETIC RESONANCE

Palabras clave: RMN Descripción: La configuración de los equipos está enfocada principalmente a la resolución de problemas de determinación estructural y estudio de procesos dinámicos, todo ello en solución. No obstante, se dispone de un accesorio de sólidos que permite abordar estudios de CPMAS. Los usuarios pueden acceder a las prestaciones del Servicio en dos modos de utilización distintos pero complementarios entre sí: en autoservicio o realización de experimentos por parte del personal del Servicio. Técnicas e instrumentación disponibles: En la actualidad el servicio dispone de un total de cuatro instrumentos de RMN:

o 2 AVANCE-400. o Bruker: ARX-300 o Varian: Unity 300

Se dispone de sondas de detección directa (BBO) e inversa (BBI), controlador para la realización de experimentos a temperatura variable entre -130 ºC y 200 ºC, cambiador automático de muestras utilizado para la adquisición de espectros de 1H ,13C, 31P y 19F. Personas de contacto: Jefe del Servicio: Dr. Esteban Urriolabeitia ([email protected]). Responsable del Servicio: Dra. Pilar Romero ([email protected]). Técnico contratada: Yolanda Nieto ([email protected]) Ubicación: Facultad de Ciencias, Edificio A, Pedro Cerbuna, 12. 50009 Zaragoza. Tel.: 976 762532/2778.

Keywords: NMR Equipment: The configuration of the equipment is directed to the resolution of structural problems and the study of dynamic processes in solution. In addition, CPMASS studies can be carried out using the solid-state accessory. Users can acquire data by themselves or through the services of the staff technicians. Available techniques: Four NMR instruments are available:

o 2 AVANCE-400. o Bruker: ARX-300 o Varian: Unity 300

Direct detection probes (BBO) and inverse detection probes (BBI) are currently used. A variable temperature accessory (-130 to 200 ºC.) is also available. An autosampler is used for acquisition of 1H , 13C, 31P, and 19F spectra. Contact persons: Head of the Service: Dr. Esteban Urriolabeitia ([email protected]). Scientist in charge: Dra. Pilar Romero ([email protected]). Technical personnel: Yolanda Nieto ([email protected]).

Address: Facultad de Ciencias, Edificio A, Pedro Cerbuna, 12. 50009 Zaragoza. Tel.: 976 762532/2778.

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ANÁLISIS TÉRMICO DIFERENCIAL / DIFFERENTIAL THERMAL ANALYSIS

Palabras clave: Análisis térmico diferencial, calorimetría, termogravimetría. Descripción del equipo: Calorímetros diferenciales de barrido Perkin-Elmer DSC-7 y Thermal Análisis TA2910. Termobalanza TA2960. Técnicas y/o instrumentación disponibles: Calorimetría diferencial de barrido (DSC) desde 120 K hasta 1000 K. Termogravimetría (TG) desde 300 K hasta 1500 K. Masa de muestra entre 5 mg y 100 mg. Personas de contacto: Prof. José Luis Serrano ([email protected]). Prof. Ramón Burriel ([email protected]). Ubicación: Facultad de Ciencias, Edificio D, Pedro Cerbuna, 12. 50009 Zaragoza. Tel.: 976 761209/1223.

Keywords: Differential thermal analysis, calorimetry, thermogravimetry. Equipment: Differential scanning calorimeters Perkin-Elmer DSC-7 and Thermal Analysis TA2910. Thermobalance TA2960. Available techniques: Differential scanning calorimetry (DSC) from 120 K to 1000 K. Thermogravimetry (TG) from 300 K to 1500 K. Sample mass between 5 mg and 100 mg. Contacts: Prof. José Luis Serrano ([email protected]). Prof. Ramón Burriel ([email protected]). Address: Facultad de Ciencias, Edificio D, Pedro Cerbuna, 12. 50009 Zaragoza. Tel.: 976 761209/12.

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2.- Actividades

Activities

91

2.1.- Líneas de Investigación Research Areas

93

2.1.1.- Ciencia y Tecnologías Químicas Chemistry: Science and Technology

95

Arquitectura molecular con compuestos organometálicos. El desarrollo de los métodos sintéticos nos permite conocer las posibilidades de preparación de compuestos de magnitud molecular controlada mediante el uso de diversas estrategias: 1) Empleo de ligandos polifuncionales con varios átomos dadores que permitan la polimerización. El grupo emplea entre otros: sacarinatos, cianuratos, alquiniluros, cianuros, alquinotiolatos, fosfinoalquinos, ligandos "pincer", ditiolatos, fosfino- y amino-carboranos y sus derivados, ferrocenil-derivados, ditiolenos, fosfuros e iluros. 2) Incremento de la magnitud molecular del compuesto por interacciones metal-metal solas o favorecidas por ligandos puente. En este apartado se explotan metalofilias e interacciones dador-aceptor entre centros metálicos de configuración de capa completa en las que el grupo ha sido pionero tanto en su descubrimiento como en su desarrollo. 3) Arquitectura molecular mediante empleo de interacciones débiles, preferentemente puentes de hidrógeno. La utilización de este tipo de interacciones no covalentes en química supramolecular es una zona del máximo interés y permite llevar a cabo la construcción de moléculas de gran tamaño en donde las interacciones débiles permiten la transferencia de determinado tipo de propiedades. 4) Desarrollo de "tectones" útiles en procesos de autorreconocimiento y capaces por sí solos o con ayuda de otras especies, de participar en procesos de crecimiento de la molécula en una, dos o tres dimensiones.

Organometallic molecular architecture Developments in synthetic methodology have opened new routes for controlling molecular size and shape through diverse preparative strategies: 1) The use of polyfunctional ligands, entities with numerous functional groups susceptible to controlled ligand reactivity leading, for example, to polymerization. Among the polyfunctional ligands currently in use are saccharinate, cyanurate, alkynylylides, cyanides, alkynylthiolates, phosphinoalkynes, pincer ligands, dithiolates, phosphino- and aminocarboranes, ferrocenyl derivatives, dithiolenes, phosphides, and ylides. 2) Molecular size enhancement through metal-metal interactions, both unsupported and bridged. This line of work also employs metallophiles and donor-acceptor interactions between closed-shell metal centers, areas in which this members of this group made pioneering discoveries and have led continued development. 3) Supermolecular architecture using weak interactions, principally hydrogen bonds. The use of non-covalent contacts in supramolecular chemistry is currently an area of increasing interest and activity, because of the possibilities that exist for creating aggregates in which intermolecular interactions permit communication of magnetic and/or electronic properties. 4) Development of tectons, which are useful in self-recognition processes and able to participate in recognition-based growth of aggregate structures in one, two, or three dimensions.

Publicaciones: J. P. H. Charmant, J. Forniés, J. Gómez, E. Lalinde, R. I. Merino, M. T. Moreno, A. G. Orpen. Synthesis and Electrical and Optical Propierties of [PtTl2-xLix(C6F5)2(C≡CPh)2] (x = 0, 1). Organometallics 2003, 22, 652-656. D. Abizanda, O. Crespo, M. C. Gimeno, J. Jiménez, A. Laguna. Synthesis and structure of new carborane-substituted cyclotriphosphazenes. Chem. Eur. J. 2003, 9, 3510-3519. P. Alvarez, E. Lastra, J. Gimeno, M. Bassetti, L. R. Falvello. Formation of a Cyclobutanediyl Ring: Intramolecular [2+2] Cycloaddition of Allyl and Vinylidene C=C Bonds under Mild Conditions. J. Am. Chem. Soc. 2003, 125, 2386-2387. Proyectos: Complejos de oro y plata. Preparación, estructura y potenciales aplicaciones (BQU2001-2409-C02-01). Compuestos organometálicos de metales de transición. Aproximaciones sintéticas a especies de interés científico por su novedad estructural o de enlace o por sus propiedades (BQU2002-3997-C02-01). Síntesis, caracterización y reactividad de complejos de paladio y platino con fosfoiluros y ligandos relacionados. Procesos de activación C-H, C-P y C-C (BQU2002-00510). Diseño, síntesis y estudio de compuestos de coordianción con ligandos polifuncionales; Cristalografía estructural no rutinaria; Informática cristalográfica (BQU2002-00554). Miembros del ICMA que participan en esta línea: J. Forniés, A. Laguna, L. R. Falvello, M. Laguna, R. Navarro, M. Tomás, M. C. Gimeno, F. Martínez, M. A. Usón, M. D. Villacampa, B. Menjón, J. M. Casas, I. Ara, E. Urriolabeitia, A. Martín, C. Fortuño, M. V. Sicilia, J. Jiménez, M. Contel, O. Crespo, E. Cerrada, N. Chaouche, B. E. Diosdado, I. Escorihuela, M. A. García, C. Larraz, L. Jones, L. F. Martín, M. T. Soler.

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Aproximaciones sintéticas y determinación estructural de compuestos de metales de transición con propiedades de interés.

Uso de técnicas novedosas tales como la electrocristalización, la electropolimerización, la cristalización progresiva y otros métodos sintéticos avanzados para preparar y aislar compuestos no favorecidos en la síntesis tradicional. De esta manera, se pretende obtener materiales moleculares, compuestos bioinorgánicos, y otras sustancias con propiedades de interés. Entre los compuestos estudiados en esta línea figuran, entre otros, agentes anti-tumorales, materiales moleculares cuyas moléculas fundamentales cambian de forma en estado sólido y polímeros novedosos. Como ejemplo de las técnicas novedosas empleadas en esta línea sirve la electrocristalización que usa corriente eléctrica para producir la cristalización de moléculas con grupos laterales polimerizables. Esta línea incluye la determinación estructural de los nuevos compuestos sintetizados, utilizando las técnicas necesarias, sean rutinarias o no, difracción de monocristal u otras técnicas. Esta linea engloba el amplio esfuerzo de este grupo en el desarrollo y uso de técnicas neutrónicas. Este grupo está involucrado en la ampliación de un difractómetro de neutrones de monocristal (Argonne National Laboratory) y en el Equipo de Diseño de un nuevo difractómetro (SNS - Oak Ridge National Laboratory) que permitirá el análisis por difracción de neutrones, empleando muestras pequeñas, lo cual abrirá nuevos horizontes en el uso de neutrones en la química organometálica.

Synthetic approaches to, and structural properties of, transition metal complexes with novel properties This line of investigation involves the development and use of novel techniques -electrocrystallization, electropolymerization, progressive crystallization- and other advanced synthetic methods. The target products include molecular materials, bioinorganic complexes, and other substances with potentially useful properties. Products obtained to date include a potential anti-tumor agent and a molecular material whose component molecule changes shape dynamically, reversibly, and non-destructively in the crystalline state. Among the techniques used to prepare new products is the electrocrystallization of molecules with polymerizable side chains. This line of research also encompasses structure determination of the new products, whether by routine or non-routine techniques involving single-crystal diffraction or another appropriate technique. This line also involves substantial effort in neutron techniques. One member of this department is involved in instrument improvement at Argonne National Laboratory and is a member of the Instrument Development Team for the Single Crystal Diffractometer at the Spallation Neutron Source (SNS) being built at Oak Ridge National Laboratory. It is expected that the new instrument at SNS will permit the use of smaller samples than presently needed for neutron analysis, thus opening new horizons for the use of neutron diffraction in inorganic chemistry.

Publicaciones: E. Alonso, J. Forniés, C. Fortuño, A. Martín, A. G. Orpen. Synthesis of Neutral and Anionic Tetranuclear Clusters [Pt4(µ2-PPh2)3{µ3-PPh(1,2-η2-Ph)-η3P}(C6F5)4L] and [NBu4][(µ2-PPh2)3{µ3-PPh(1,2-η2-Ph)-η3P}(C6F5)5] Containing Five Coordinate P Atoms and two Pt-Pt Bonds. Organometallics 2003, 22, 2723-2728. E. J. Fernández, J. M. López-de-Luzuriaga, M. Monge, M. E. Olmos. J. Pérez, A. Laguna, A. A. Mohamed, J. P. Fackler. {Tl[Au(C6Cl5)2]}n: A Vapochromic Complex. J. Am. Chem. Soc. 2003, 125, 2022-2023. I. Ara, J. Forniés, M. A. García-Monforte, B. Menjón, R. M. Sanz-Carrillo, M. Tomás, A. C. Tsipis. Synthesis and Characterisation of New Five-Coordinated Platinum Nitrosyl Derivatives: Density Functional Theory Study of Their Electronic Structure. Chem. Eur. J. 2003, 9, 4094-4105. I. P. Aleksandrova, J. Bartolomé, L. R. Falvello, J. M. Torres, A. A. Sukhovskii. Effect of Impurities on the Successive Phase Transitions in (Cs1-xRbx)2ZnI4 Compounds. J. Phys. Condens. Matt. 2002, 14, 13623-13634. Proyectos: Complejos de oro y plata. Preparación, estructura y potenciales aplicaciones (BQU2001-2409-C02-01). Compuestos organometálicos de metales de transición. Aproximaciones sintéticas a especies de interés científico por su novedad estructural o de enlace o por sus propiedades (BQU2002-3997-C02-01). Síntesis, caracterización y reactividad de complejos de paladio y platino con fosfoiluros y ligandos relacionados. Procesos de activación C-H, C-Py C-C (BQU2002-00510). Diseño, síntesis y estudio de compuestos de coordianción con ligandos polifuncionales; Cristalografía estructural no rutinaria; Informática cristalográfica (BQU2002-00554). Miembros del ICMA que participan en esta línea: J. Forniés, A. Laguna, L. R. Falvello, M. Laguna, M. Tomás, M. C. Gimeno, F. Martínez, M. A. Usón, M. D. Villacampa, B. Menjón, J. M. Casas, I. Ara, A. Martín, C. Fortuño, M. V. Sicilia, J. Jiménez, M. Contel, O. Crespo, E. Cerrada, N. Chaouche, B. E. Diosdado, N. Lardiés, L. Jones, M. A. Luquín.

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Propiedades ópticas, eléctricas y magnéticas a través de procesos de autorreconocimiento Estamos interesados en la preparación de nuevos compuestos homo- y heteropolinucleares que presenten propiedades ópticas, eléctricas o magnéticas de interés. Para ello estamos utilizando diferentes métodos sintéticos, entre los que destacan las reacciones entre complejos o fragmentos con comportamiento ácido de Lewis con otros de comportamiento básico. Esta aproximación nos está permitiendo obtener, por ejemplo, un importante número y variedad de complejos polinucleares con enlaces, u otro tipo de interacciones débiles, entre diferentes centros metálicos o con puentes de hidrógeno. Algunos de los compuestos preparados presentan propiedades luminiscentes y es posible modificar la frecuencia de emisión al variar el entorno de coordinación o la distancia entre los centros metálicos. Otros derivados, por ejemplo, los obtenidos por interacción entre dadores y aceptores de densidad electrónica o los que contienen cadenas de centros metálicos, presentan interesantes propiedades semiconductoras y de óptica no lineal. Estamos estudiando también las interacciones magnéticas que se presentan a través de interacciones intermoleculares débiles.

Developing electronic, optical, and magnetic properties through self-recognition We are interested in preparing new homo- or heteropolynuclear compounds with useful electronic, optical, or magnetic properties. To this end we are employing diverse synthetic processes, such as Lewis acid-base reactions between different complexes or molecular fragments. Our approach has led to the obtention of a growing number and variety of polynuclear complexes with metal-metal bonds, with weak inter-metal interactions, or with hydrogen bonds. Some of the compounds obtained so far are luminescent, and the emission frequency can be modified by varying the coordination environment of the metal or the metal-metal distance. Other products, some formed by interaction of electron donors and acceptors and others which contain chains of metal atoms, display non-linear optical and semiconductor properties. In this line of research we are also studying magnetic interactions mediated by weak intermolecular contacts.

Publicaciones: M. Bardají, P. Uznanski, C. Amiens, B. Chaudret, A. Laguna. Aurophilic complexes as gold atom sources in organic media. Chem. Commun. 2002, 598-599. E. Alonso, J. Forniés, C. Fortuño, A. Martín. A. G. Orpen. Reactivity of [NBu4][(C6F5)2M(µ-PPh2)2M'(acac-O,O')] (M, M' = Pt, Pd) towards silver centers. Synthesis of polynuclear complexes containing M-Ag bonds (M = Pd, Pt). Organometallics 2003, 22, 5011-5019. M. Bardají, A. Laguna, M. R. Pérez, P.G. Jones. Unexpected ring-opening reaction to a new cyanamide-thiolate ligand stabilized as a dinuclear gold complex. Organometallics 2002, 21, 1877-1881. L. R. Falvello, E. M. Miqueleiz, M. Tomás. Effect of Supramolecular Aggregation on Coordination in Cobalt (II) Complexes of 2-Imidazolidone. Indian J. Chem. A 2003, 42A, 2307-2315. Proyectos: Complejos de oro y plata. Preparación, estructura y potenciales aplicaciones (BQU2001-2409-C02-01). Compuestos organometálicos de metales de transición. Aproximaciones sintéticas a especies de interés científico por su novedad estructural o de enlace o por sus propiedades (BQU2002-3997-C02-01). Síntesis, caracterización y reactividad de complejos de paladio y platino con fosfoiluros y ligandos relacionados. Procesos de activación C-H, C-Py C-C (BQU2002-00510). Diseño, síntesis y estudio de compuestos de coordianción con ligandos polifuncionales; Cristalografía estructural no rutinaria; Informática cristalográfica (BQU2002-00554). Miembros del ICMA que participan en esta línea: J. Forniés, A. Laguna, L. R. Falvello, M. Laguna, R. Navarro, M. Tomás, M. C. Gimeno, F. Martínez, M. A. Usón, M. D. Villacampa, B. Menjón, J. M. Casas, I. Ara, E. Urriolabeitia, A. Martín, C. Fortuño, M. V. Sicilia, J. Jiménez, M. Contel, O. Crespo, E. Cerrada, I. Escorihuela, M. A. García, C. Larraz, L. Jones, L. F. Martín, M. T. Soler.

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Procesos estequiométricos y catalíticos de formación de enlaces carbono-carbono y carbono-heteroátomo por mediación de compuestos de coordinación. Comprende el estudio de reacciones de formación de enlaces C-X, donde X puede ser un átomo de carbono u otro elemento como oxígeno o nitrógeno, realizadas por la presencia de compuestos de coordinación. Comprende tanto procesos estequiométricos, esto es, reacciones que se realizan de esta determinada manera por el papel que juega el metal de transición coordinado o no con los reactivos, como procesos en los que los compuestos de coordinación actúan de catalizadores para una síntesis orgánica dirigida tanto en procesos homogéneos como heterogéneos. Para este fin se utilizan compuestos de paladio(II), platino(II), oro(l) y oro(llI) y los procesos a estudiar son reacciones de acoplamiento C-C del tipo de Heck, Suzuki o Stille, así como reacciones de hidratación e hidroaminación de alquinos. Se presta especial atención al estudio de los mecanismos por los que evolucionan, y al aislamiento de posibles intermedios de reacción; estamos extendiendo estos estudios a determinados procesos de síntesis asimétrica.

Stoichiometric and catalytic carbon-carbon and carbon-heteroatom bond formation reactions mediated by coordination complexes This line of research consists of the study of C-X bond formation reactions, in which X can be carbon or another element such as oxygen or nitrogen, in the presence of coordination compounds. Included are stoichiometric processes -- reactions in which the transition metal plays a role in determining the reaction pathway, whether or not the reactants are bonded to the metal -- as well as specific organic reactions in which coordination compounds act as homogeneous or heterogeneous catalysts. Compounds of palladium(II), platinum(II), gold(I), and gold(III) are used in studies of C-C coupling reactions (Heck-, Suzuki-, or Stille-type), as well as in studies of alkyne hydration or hydroamination reactions. Special emphasis is given to the study of the reaction mechanisms and the isolation of possible reaction intermediates. This line of research is presently being expanded to encompass the study of selected asymmetric syntheses.

Publicaciones L. R. Falvello, M. E. Margalejo, R. Navarro, R. Llusar, E. P. Urriolabeitia. Stabilized bis-ylides as a source of Carbene ligands in Palladium(II) and Platinum(II) complexes. Organometallics 2003, 22, 1132-1144. C. Gracia, G. Marco, R. Navarro, P. Romero, T. Soler, E. P. Urriolabeitia. C-P and C-H bond activaions and C-C coupling in Bis-Phosphonium salts induced by Pt(II) complexes. Organometallics 2003, 22, 4910-4921. P. Merino, T. Tejero, M. Laguna, E. Cerrada, A. Moreno, J. A. Lopez. An investigation of the 1,3-dipolar cycloaddition reactions of N-benzyl-C-(2-pyridyl) nitrone. Direct entry to isoxazolidinyl C-nucleosides. Org. Biomol. Chem. 2003, 1, 2336-2342. M. Contel, C. Izuel, M. Laguna, P. R. Villuendas, P. J. Alonso, R. H. Fish. Fluorous biphasic catalysis: Synthesis and characterization of Copper(I) and Copper(II) fluoroponytailed 1,4,7-Rf-TACN and 2,2’-Rf-Bipyridine complexes, and demonstration of their catalytic activity in the oxidation of hydrocarbons, olefins, and alcohols, including mechanistic implications. Chem. Eur. J. 2003, 9, 4168-4178. R. Casado, M. Contel, M. Laguna, M. P. Romero, S. Sanz. Organometallic Gold(III) compounds as catalysts for the addition of water and methanol to terminal alkynes. J. Am. Chem. Soc. 2003, 125, 11925-11935. Proyectos: Síntesis, caracterización y reactividad de complejos de paladio y platino con fosfoiluros y ligandos relacionados. Procesos de activación C-H, C-P y C-C (BQU2002-00510). Miembros del ICMA que participan en esta línea: M. Laguna, R. Navarro, M. E. Urriolabeitia, M. Contel, E. Cerrada, N. Lardiés, L. Jones, M. A. Luquín.

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Diseño y síntesis de catalizadores. Estudios mecanísticos. La investigación en esta línea persigue la concepción y síntesis de nuevos complejos de metales de transición con características adecuadas para actuar como catalizadores homogéneos. Este tipo de complejos son, por lo general, especies coordinativamente insaturadas o lábiles, esto es, que poseen o pueden generar con facilidad vacantes de coordinación, y contienen ligandos que les confieren adecuadas prestaciones electrónicas, estéricas o de estabilidad. Los nuevos complejos son sometidos a estudios sistemáticos sobre su comportamiento en disolución y su reactividad frente a pequeñas moléculas y sustratos generalmente involucrados en transformaciones catalíticas, con atención preferente sobre los aspectos mecanísticos que puedan repercutir en la cinética o la selectividad de las transformaciones. Esta información permite identificar las aplicaciones catalíticas idóneas de estos complejos o diseñar nuevos procesos catalíticos. Estas aplicaciones y procesos se someten a una caracterización mecanística que proporcione las claves para la optimización de los procesos y el re-diseño de catalizadores más activos y selectivos. La metodología de esta línea está basada fundamentalmente en el uso de técnicas sintéticas y espectroscópicas, estas últimas fundamentalmente encaminadas a la realización de estudios cinéticos y la detección de especies reactivas e intermedios catalíticos.

Catalysis design and synthesis. Mechanistic studies. This research line is aimed at the design and synthesis of new transition metal complexes with potential application as homogeneous catalysts. In general, these compounds are unsaturated or labile species, therefore featuring coordination vacancies or a facile access to them, and contain ancillary ligands conferring adequate electronic, steric or stability properties. The solution behavior of the compounds and their reactivity towards small molecules and substrates commonly involved in catalytic transformations are systematically investigated, with emphasis on those mechanistic aspects likely to affect the rate and selectivity of the reactions. This information allows to recognize successful catalytic applications of the new complexes and can enlighten the development of new processes. Such applications and processes are subjected to a mechanistic characterization providing key information for process optimization and catalyst re-design. This line uses a research methodology based on synthetic and spectroscopic techniques, the latter being mainly focused on kinetic studies and the detection of reactive species and catalytic intermediates.

Publicaciones: M. Martín, E. Sola, O. Torres, P. Plou, L. A. Oro. Versatility of cyclooctadiene ligands in Iridium chemistry and catalysis. Organometallics 2003, 22, 5406-5417. M. V. Jiménez, E. Sola, J. Caballero, F. J. Lahoz, L. A. Oro. Alkene C-H activations at dinuclear complexes promoted by oxidation. Angew. Chem. Int. Ed. 2002, 41, 1208-1211. Y. Yuan, M. V. Jiménez, E. Sola, F. J. Lahoz, L. A. Oro. Sequential C-H activation and dinuclear insertion of ethylene promoted by a Diiridium complex. J. Am. Chem. Soc. 2002, 124, 752-753. Proyectos: Desarrollo de aplicaciones catalíticas homogéneas promovidas por complejos de metales de transición (BQU2003-05412-C02-01). Desarrollo de aplicaciones catalíticas homogéneas promovidas por complejos de metales de transición (BQU2003-05412-C02-02). Catálisis homogénea por complejos organometálicos de metales de transición (BQU2000-1170). Integral training and research in homogeneous catalysis by organometallic compounds (HPMT-CT-2000-00200). Miembros del ICMA que participan en esta línea: L. A. Oro, E. Sola, J. J. Pérez-Torrente, V. Jiménez, J. A. López, F. J. Lahoz, A. I. Elduque, M. Martín, J. Navarrro, A. Acosta, S. Tejero, O. Torres, P. Plou.

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Complejos polinucleares homo y heterometalicos. Los compuestos polimetálicos, que incluyen a los complejos dinucleares, polinucleares y clusters, gozan de una posición intermedia entre los complejos mononucleares y las superficies metálicas. La presencia de, al menos, dos átomos metálicos en una misma molécula permite la interacción de sustratos orgánicos con un centro metálico (single site) en presencia de otro próximo, que puede reactivarlo, o simultáneamente con dos o varios centros metálicos (multisite) facilitando la activación y transformación del sustrato en productos. En esta dirección, estudiamos la reactividad asociada a más de un centro metálico buscando actuaciones sinérgicas de los metales y preparamos clusters metálicos como modelos moleculares de superficies metálicas. Alternativamente, se sintetizan dendrímeros funcionalizados en la superficie que pueden actuar como soportes para la incorporación de metales activos en reacciones catalíticas, que son fácilmente separables de los productos de reacción. Una dirección relevante en la síntesis de complejos polinucleares es nuestra orientación hacia la preparación de compuestos con una determinada estructura. En particular, estamos interesados en la preparación de oligómeros metálicos unidimensionales y cadenas metálicas (“metal-wires”) mediante la formación de enlaces metal-metal, susceptibles de presentar propiedades conductoras.

Homo and heterometallic polynuclear complexes. The polymetallic compounds, including dinuclear, polynuclear complexes and metal clusters, benefit an intermediate position between the mononuclear complexes and the metal surfaces. The presence of two metal atoms in a molecule allows the interaction of organic substrates with either a metal centre (single site) in the nearby of another close metal, which can reactivate it, or with two or more metal centres (multisite). In this way the activation and transformation of the substrate into products can be facilitated. With this aim, we are studying the reactivity associated to more than one metal centre looking for a synergism of the metals, and we prepare metal clusters as molecular models of metallic surfaces. Alternatively, we are synthesising surface-functionalized dendrimers to act as soluble supports for complex metal fragments active in catalytic reactions, which can be easily separated from the products. A relevant direction in the syntheses of polynuclear complexes is our orientation to prepare compounds with special structures. In particular, we are interested in the preparation of 1D metal oligomers and metal chains (metal wires) through the formation of metal-metal bonds, which could show electrical conductivity.

Publicaciones: C. Tejel, M. A. Ciriano, M. Bordonaba, J. A. López, F. J. Lahoz, L. A. Oro. Structural and dynamic studies on amido bridged Rhodium and Iridium complexes. Chem. Eur. J. 2002, 8, 3128-3138. C. Tejel, M. A. Ciriano, B. E. Villarroya, J. A. López, F. J. Lahoz, L. A. Oro. A hexanuclear Iridium chain. Angew. Chem. Int. Ed. 2003, 42, 529-532. M. A. Casado, J. J. Pérez-Torrente, M. A. Ciriano, I. T. Dobrinovitch, F. J. Lahoz, L. A. Oro. Stereoselective oxidative-additions of iodoalkanes and activated alkynes to a sulfido-bridged heterotrinuclear early-late (TiIr2) complex. Inorg. Chem. 2003, 42, 3956-3964. Proyectos: Nuevos clusters y cadenas metálicas basadas en rodio e iridio y reactividad binuclear (PB98-0641). Síntesis, estructura y reactividad de complejos mono- y poli-metálicos con posibles aplicaciones catalíticas o conductoras (BQU2002-0074). Miembros del ICMA que participan en esta línea: M. A. Ciriano, C. Tejel, B. E. Villarroya, M. A. Casado, J. A. Camerano, S. Jiménez.

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Catalizadores organometálicos enantioselectivos. Muchos de los constituyentes de los seres vivos son ópticamente activos. En consecuencia, los receptores biológicos habitualmente diferencian entre los dos enantiómeros de una molécula con actividad biológica. Esta característica hace que la demanda de compuestos quirales con elevada pureza enantiomérica esté creciendo de manera espectacular durante los últimos años. La forma más eficaz, sin ninguna duda, de llevar a cabo las síntesis de productos enantioselectivamente es la catálisis. Mediante el empleo de un auxiliar quiral, con una sola molécula de un catalizador se puede obtener un número elevado de moléculas del producto quiral deseado. En la línea de investigación “Catalizadores Organometálicos Enantioselectivos” se aborda la preparación de compuestos organometálicos quirales de metales del grupo del platino y el estudio de su actividad como catalizadores en procesos catalíticos en fase homogénea de transferencia de hidrógeno, Diels-Alder, adiciones de Michael y cicloadiciones 1,3-dipolares de alquenos a nitronas. Como objetivo principal figura el estudio de los ciclos catalíticos implicados. Para ello, se intenta detectar y caracterizar los intermedios organometálicos que participan en los mismos. Su caracterización permite proponer los caminos de reacción que operan, optimizar los sistemas catalíticos y proponer el origen de la selectividad, en particular la enantioselectividad, de los mismos.

Organometallic enantioselective catalysts. Most of the constituents of live beings are optically active. Thus, the biological receptors usually distinguish between the two enantiomers of a biologically active molecule. This fact causes that the industrial demand of chiral compounds with high enantiomeric purity is growing in a spectacular way during the last years. The most efficient way, without any doubt, to carry out the enantioselective synthesis of products is Catalysis. Using a chiral auxiliary, just with only one catalyst molecule, it is possible to obtain a great number of molecules of the needed chiral compound. In the research line “Organometallic Enantioselective Catalysts” we attempt the preparation of quiral organometallic compounds based on platinum group metals and the study of their catalytic activity in homogeneous processes such as hydrogen transfer reactions, Diels-Alder, Michael additions and 1,3-dipolar cycloadditions of alkenes to nitrones. The main objective is the study of the catalytic cycles attempting the detection and characterisation of the involved organometallic intermediates. From their characterisation it is possible to propose the catalytic reaction paths, to optimise the catalytic systems, to explain the observed selectivities and to propose the origin of the enantioselectivity.

Publicaciones: D. Carmona, F. J. Lahoz, S. Elipe, L. A. Oro, M. P. Lamata, F. Viguri, F. Sánchez, S. Martínez, C. Cativiela, M. P. López Ram-de-Víu. Synthesis, characterization, properties, and asymmetric catalytic Diels-Alder of chiral-at-metal phosphinooxazoline-Rhodium(III) and-Iridium(III) complexes. Organometallics 2002, 21, 5100-5114. D. Carmona, M. P. Lamata, F. Viguri, I. T. Dobrinovich, F. J. Lahoz, L. A. Oro. On the sense of the enantioselection in hydrogen transfer reactions from 2-propanol to ketones. Adv. Synth. Catal. 2002, 344, 499-502. D. Carmona, M. P. Lamata, L. A. Oro. Half-sandwich complexes with chiral ligands and their use as enantioselective catalysts. Eur. J. Inorg. Chem. 2002, 2239-2251. Proyectos: Síntesis y caracterización de organocomplejos quirales en el metal: aplicaciones en catálisis enantioselectiva (BQU-2000-0907). Catálisis enantioselectiva por compuestos organometálicos (BQU-2003-01096). Miembros del ICMA que participan en esta línea: D. Carmona, M. P. Lamata, F. Viguri, J. Ferrer, M. Esteban .

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Relación estructura-actividad en complejos metálicos polinucleares. Esta área de investigación persigue el establecimiento de una relación entre la estructura -molecular y electrónica-, de nuevos compuestos de coordinación, generalmente polinucleares, y su reactividad química o, en su caso, actividad catalítica. Se pretende el diseño racional, a partir de los estudios de naturaleza estructural, de nuevos complejos multimetálicos con potencial reactividad relevante en el entorno de la catálisis homogénea, explotando el uso de ligandos puente polidentados. Se trata de aportar información estructural para la comprensión de los mecanismos por los que se producen determinados procesos reactivos o catalíticos, de acotar el procedimiento por el que se verifican los efectos cooperativos entre centros metálicos, así como de extender a la química polinuclear la aplicación de aquellos efectos electrónicos básicos de utilidad en química mononuclear. Esta información se obtiene a partir de estudios de estructura molecular y electrónica, conjugando medidas experimentales de difracción, con cálculos teóricos de química computacional de distintos grados de precisión. Adicionalmente, esta línea de trabajo dedica especial atención al estudio de los empaquetamientos cristalinos, información ésta de vital importancia en la identificación de interacciones débiles de no-enlace, básicas, a su vez, en procesos de reconocimiento molecular y de aplicación en química supramolecuar y en ingeniería cristalina.

Structure-activity relationship in polynuclear metal complexes. This research area aspires to the establishment of a relationship between the molecular and electronic structure of new coordination,- generally polynuclear,- complexes and their chemical reactivity and, in some cases, their catalytic activity. Exploiting the use of bridging polydentate ligands, our approach aims the rational design –based on the structural knowledge- of multimetallic complexes with potential reactivity in the field of homogeneous catalysis. We search for structural information to understand particular reactive or catalytic processes, to establish the mechanism by which the cooperative synergetic effects take place among metals, and to extend to polynuclear chemistry the application of basic electronic effects of general use in mononuclear chemistry. This information is obtained from molecular and electronic structural studies, putting together experimental diffraction measurements with computational theoretical calculations carried out at different precision levels. Additionally, this project also searches with special interest the identification of non-bonding weak interatomic interactions, basic information in the understanding of intermolecular auto-assembling, and with great application in supramolecular chemistry and crystal engineering.

Publicaciones: A. P. Martínez, M. P. García, F. J. Lahoz, L. A. Oro. The unexpected synthesis of rhodium(I) complexes with the 1-(2´-pyridyl)-3-oxo-1-propenoxide anionic ligand. Inorg. Chem. Commun. 2002, 5, 254-258. A. P. Martínez, M. P. García, F. J. Lahoz, L. A. Oro. The rhodium and iridium co-ordination chemistry of the hemilabile hybrid ligand 1-pyridil-3-dimethylamino-2-propen-1-one. Inorg. Chim. Acta 2003, 347, 86-98. M. A. F. Hernández-Gruel, J. J. Pérez-Torrente, M. A. Ciriano, A. B. Rivas, F. J. Lahoz, I. T. Dobrinovitch, L. A. Oro. Synthesis, reactivity and catalytic activity of triangular ZrM2 (M=Rh, Ir) early-late heterobimetallic complexes. Organometallics 2003, 22, 1237-1249. Proyectos: Complejos organometálicos polinucleares de rodio e iridio. Síntesis, estructura y reactividad (PB98-1598). Relación estructura/reactividad en complejos polinucleares de rodio e iridio (BQU2002-01729). Miembros del ICMA que participan en esta línea: F. J. Lahoz, M. P. García, F. J. Modrego, J. A. López, I. T. Dobrinovitch, A. P. Martínez, A. Balana.

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Diseño de nuevas reacciones promovidas por complejos de metales de transición. Aplicaciones en catálisis homogénea. Usando como plantillas complejos de coordinación de metales de transición se pretende, a través de sucesivas reacciones de acoplamiento carbono-carbono y carbono-heteroátomo, la síntesis de moléculas orgánicas funcionalizadas a partir de hidrocarburos básicos. Esta línea se centra principalmente en la preparación de nuevos compuestos polihidruro y en el estudio de su reactividad frente a moléculas orgánicas insaturadas (alquinos, olefinas, cetonas, …), en la preparación de compuestos con ligandos carbono, en la síntesis de complejos con una función hemilábil, y en reacciones de ciclohidroaminación Se buscan nuevos catalizadores homogéneos para reacciones conocidas como por ejemplo, polimerización de α-olefinas, oligomerización y polimerización de alquinos, dehalogenación de compuestos orgánicos, hidroaminación de alquinos y olefinas, etc.

Design of new reactions promoted by transition metal complexes. Applications in homogeneous catalysis. Using as a template coordination complexes of transition metals (M) we intend, following successive reactions of carbon-carbon and carbon-heteroatom coupling reactions, the synthesis of functionalized organic molecules starting from basic hydrocarbons. This research line is focused mainly in the preparation of new polyhydride complexes and the study of their reactivity towards unsaturated organic molecules (alkynes, olefines, ketones, …), in the preparation of compounds with carbene ligands, in the synthesis of complexes containing an hemilabil function, and in cyclohydroamination reactions. We are looking for new homogeneous catalysts for known reactions such as α-olefin polymerization, oligomerization and polymerization of alkynes, dehalogenation of organic compounds, hydroamination of alkynes and olefins, etc.

Publicaciones: M. A. Esteruelas, A. I. González, A. M. López, E. Oñate. An Osmium-carbene complex with Fischer-Schrock ambivalent behaviour. Organometallics 2003, 22, 414-425. M. L. Buil, M. A. Esteruelas, A. M. López, E. Oñate. C-N and C-C coupling reactions: Preparation of new n-heterocyclic Ruthenium derivatives. Organometallics 2003, 22, 162-171. M. A. Esteruelas, A. M. López, L. Méndez, M. Oliván y E. Oñate. Preparation, structure, and ethylene polymerization behavior of bis(imino)pyridyl Chromium(III) complexes. Organometallics 2003, 22, 395-406. Proyectos: Reacciones estequiométricas y catalíticas de acoplamiento carbono-carbono y carbono-heteroátomo promovidas por complejos de metales de transición (BQU2002-00606). Nuevos catalizadores homogéneos para la hidrogenación de dobles enlaces de polímeros o copolímeros de dienos conjugados (PPQ2000-0488-P4-02). Nuevos catalizadores para la polimerización de α-olefinas (Repsol Petróleo, S. A.) Miembros del ICMA que participan en esta línea: M. A. Esteruelas, A. M. López de Lama, M. L. Buil, M. Oliván, E. Oñate, E. Royo, F. J. Fernández, A. Asensio, T. Bolaño, B. Eguidor, A. I. González, Y. Hernández, A. C. Mateo.

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Aminoácidos y péptidos El primer objetivo del grupo de investigación consiste en desarrollar nuevas metodologías para la síntesis diastereoselectiva de aminoácidos y otros productos de interés biológico en forma enantiopura con buenos rendimientos y selectividades y usando productos de partida sencillos y económicos. Para ello, se estudian diferentes tipos de reacciones como adición de nucleófilos sobre iminas quirales, alquilación de enolatos y reacciones de cicloadición. Estas metodologías han permitido la síntesis de numerosas familias de compuestos de interés biológico en forma enantioméricamente pura. El segundo objetivo consiste en aplicar las estrategias necesarias para desarrollar la síntesis en forma enantiopura de diferentes tipos de aminoácidos conformacionalmente restringidos cuidadosamente seleccionados para ser incorporados en péptidos modelo con el propósito de conocer sus tendencias conformacionales y correlacionar así la restricción impuesta al aminoácido con el tipo de estructura adoptada por el péptido. En la actualidad, la atención está centrada en análogos restringidos de fenilalanina pero está previsto ampliar el estudio a derivados de prolina y otros aminoácidos relacionados. Ya que es necesario disponer de ambos enantiómeros del aminoácido y en cantidades significativas, se recurre a la utilización de procedimientos de resolución, fundamentalmente HPLC en fases estacionarias quirales, sobre precursores racémicos de los aminoácidos necesarios. Finalmente, se contempla la incorporación de alguno de estos aminoácidos restringidos en un péptido de interés biológico.

Amino acids and peptides The research group is first devoted to the development of new methodologies to the diastereoselective synthesis of amino acids and other products of biological interest in enantiomerically pure form with high yields and selectivities and starting from easily available materials. To this aim, different reactions such as nucleophilic addition on chiral imines, diastereolective alkylation of enolates and cycloaddition reaction are used. These methodologies have allowed the synthesis of several families of biologically interesting compounds in enantiomerically pure form. Next, the appropriate methodologies are applied to the synthesis, in enantiomerically pure form of selected conformationally restricted amino acids. These constrained amino acids are incorporated into model peptides to determine their conformational tendencies and thus establish a correlation between the restriction introduced on the amino acid and the structure accommodated by the peptide. This study is presently directed to the constrained phenylalanine analogues and will continue with proline derivatives and other related constrained amino acids. Since for this purpose significant amounts of both enantiomers of the amino acid are required, the synthesis is performed by resolution of a racemic precursor using mainly HPLC on chiral stationary phases. Finally, the incorporation of some of these restricted amino acids into a biologically active peptide will be considered.

Publicaciones: A. M. Gil, E. Buñuel, A. I. Jiménez, C. Cativiela. Stabilisation of the type I β-turn conformation by a bicyclic analogue of proline. Tetrahedron Lett. 2003, 44, 5999-6002. C. Peggion, F. Formaggio, M. Crisma, C. Toniolo, A. I. Jiménez, C. Cativiela, B. Kaptein, Q. B. Broxterman, M. Saviano, E. Benedetti. Folding of peptides characterized by c3Val, a highly constrained analogue of valine. Biopolymers 2003, 68, 178-191. R. Badorrey, C. Cativiela, M. D. Díaz-de-Villegas, J. A. Gálvez. Highly convergent stereoselective synthesis of chiral key intermediates in the synthesis of Palinavir from imines derived from L-glyceraldehyde. Tetrahedron 2002, 58, 341-354. A. Avenoza, M. París, J. M. Peregrina, M. Alías, M. P. López, J. I. García, C. Cativiela. Aspartame analogues containing 1-amino-2-phenylcyclopropanecarboxylic acids (c6Phe). Tetrahedron 2002, 58, 4899-4905. Proyectos: Nuevos aminoácidos en forma enantiomericamente pura. Diseño, síntesis e incorporación en péptidos con interés estructural, industrial y/o biológico (PPQ2001-1834). Miembros del ICMA que participan en esta línea: C. Cativiela, M. D. Díaz de Villegas, J. A. Gálvez, M. P. López, A. I. Jiménez, R. Badorrey, M. Alías, A. M. Gil, M. Lasa, R. Díez, S. Royo, G. Ballano, D. Aguirre, D. Casabona, P. Etayo.

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Catálisis heterogénea en síntesis orgánicas selectivas-procesos orgánicos sostenibles. El grupo de investigación está interesado especialmente en el desarrollo de procesos orgánicos “verdes” mediante la búsqueda de reacciones más eficientes (más selectivas y con menor gasto energético) y más respetuosas con el medio ambiente, utilizando reactivos y catalizadores menos peligrosos. Nuestro grupo ha preparado varios tipos de catalizadores sólidos basados en arcillas, sílices, óxidos mixtos, fosfatos y resinas orgánicas, con propiedades ácidas o básicas. Estos catalizadores pueden aplicarse eficientemente a diferentes reacciones de formación de enlaces C–C y oxidación, como la epoxidación de alquenos con H2O2. En la mayoría de los casos, estos sólidos presentan una elevada actividad catalítica, con una excelente selectividad, y compiten ventajosamente con los catalizadores tradicionales en disolución. En algunos casos, inducen nuevas reacciones y permiten trabajar en condiciones “verdes”, como en ausencia de disolvente o con activación por microondas. La inmovilización de catalizadores quirales para su uso en síntesis enantioselectiva ha permitido obtener catalizadores, que conjugan una alta enantioselectividad con una reutilización fácil y eficiente. La eficiencia del catalizador depende esencialmente de la naturaleza del soporte y la estrategia de inmovilización. La comprensión de la influencia de estos factores está basada en el mecanismo de reacción. En los últimos años, se ha ampliado el campo de investigación en Química Sostenible, con el estudio de reacciones en líquidos iónicos, disolventes interesantes y no volátiles, con un nulo impacto en la atmósfera.

Heterogeneous catalysis in selective organic syntheses-sustainable organic processes. The research group is mainly concerned in the development of green organic processes, by searching for more efficient (more selective and less energy-requiring) and more environment-respectful reactions, using less hazardous reactants and catalysts. Several kinds of solid catalysts based on clays, silica, mixed oxides, phosphates and organic resins with acid or basic properties have been prepared by our group. These catalysts can be efficiently applied to different C–C bond forming and oxidation reactions, such as alkene epoxidation with H2O2. In most cases, these solids present a high catalytic activity, with an excellent selectivity, and advantageously compete with usual catalysts in solution. In some cases, they promote new reactions and allow to work in green conditions, such as no-solvent reactions or microwave activation. The immobilization of chiral catalysts for their use in enantioselective Synthesis allowed to obtain excellent catalysts, conjugating a high enantioselectivity with a ready efficient reuse. Catalyst performance strongly depends on the nature of the support and the immobilization strategy, the understanding of the influence of these factors being based on the reaction mechanism. In the last years, our research field in Green Chemistry has been enlarged, with the study of reactions in ionic liquids, interesting and non-volatile neotheric solvents with negligible impact on the atmosphere.

Publicaciones: A. Cornejo, J. M. Fraile, J. I. García, M. J. Gil, G. Legarreta, S. V. Luis, V. Martínez-Merino, J. A. Mayoral. The first immobilization of pyridine-bis(oxazoline) chiral ligands. Org. Lett. 2002, 4, 3927-3930. J. M. Fraile, J. I. García, J. A. Mayoral, L. Salvatella, E. Vispe, D. R. Brown, G. Fuller. Experimental and theoretical studies on structure-reactivity relationships of titanium-modified silicas in hydrogen peroxide-promoted oxidation of cyclohexene. J. Phys. Chem. B 2003, 107, 519-526. C. Cativiela, J. M. Fraile, J. I. García, B. Lázaro, J. A. Mayoral, A. Pallarés. Heterogeneous catalysis in the synthesis and reactivity of allantoin. Green Chem. 2003, 5, 275-277. Proyectos: Síntesis de hidantoínas racémicas 5-sustituidas precursoras de aminoácidos ópticamente puros por vía enzimática (PPQ2000-0322-P4-02). Desarrollo de nuevos catalizadores enantioselectivos inmovilizados estables y reutilizables, basados en ligandos procedentes de aminoalcoholes (PPQ2002-04012-C03-01). Miembros del ICMA que participan en esta línea: J. A. Mayoral, J. I. García, J. M. Fraile, L. Salvatella, E. Pires, C. Herrerías, E. Vispe, G. Lafuente, I. Villalba, I. Pérez-Grijalbo, R. Tahir.

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Química bioorgánica El desarrollo de nuevas metodologías de producción a escala de laboratorio de compuestos biológicamente activos que permitan resolver problemas de interés biomédico es un objetivo preferente dentro de la Química. La preparación eficiente y selectiva, mediante procesos de Síntesis Química, de diversas biomoléculas como nucleósidos, carbohidratos y aminoácidos, así como estructuras moleculares análogas, es fundamental para alcanzar la diversidad funcional necesaria para la realización de estudios suficientemente amplios que lleven a resultados fiables. La síntesis química de las moléculas objetivo, se hace a través del estudio de reacciones químicas sobre grupos funcionales que permitan elaboraciones posteriores. Los procesos de adición nucleófila a sistemas insaturados de tipo C=X, entre los que se pueden incluir aldehídos, cetonas, nitronas, hidrazonas e iminas adquieren gran importancia dada su reactividad y los productos finales que proporcionan. El estudio de dichas reacciones químicas implica también la utilización y puesta a punto de nuevos métodos de síntesis que, además de aumentar la eficiencia de los procesos, contribuyen al empleo de condiciones no contaminantes y que pueden incluirse dentro de la denominada Química Verde. Entre estos métodos cabe destacar procesos de síntesis en fase sólida, química combinatoria, empleo de catalizadores, disolventes iónicos, etc. Entre las actividades biológicas perseguidas mediante los procesos de síntesis propuestos se encuentran actividades antivirales, antitumorales y antibióticas, principalmente. No obstante, el tipo de compuestos que se preparan permite ampliar la búsqueda a otras actividades relacionadas con la terapeútica de enfermedades autoinmunes (artritis reumatoide, Chron, etc.) o metabólicas (diabetes, etc).

Bioorganic chemistry The development of new methodologies at a lab scale leading to biologically active compounds with the aim of resolving biomedic problems is a preferential objective within Chemistry. The efficient and selective preparation, through synthetic chemistry processes, of several biomolecules, including nucleosides, carbo-hydrates and aminoacids, as well as, structural analogues, must be pursued in order to raise the functional diversity needed for carrying out reliable studies. The chemical synthesis of the target molecules should be done through the study of the corresponding chemical reactions on functional groups allowing further chemical manipulations. Nucleophilic addition reactions to unsaturated systems of type C=X, such as, aldehydes, ketones, nitrones, hydrazones and imines are important processes because of their reactivity and the final products obtained after treatment. The study of those reactions also needs of new synthetic methods that, in addition to increase the efficiency of the processes, will contribute to the use of clean conditions to be included into the so-called Green Chemistry. Solid-phase synthesis, combinatorial chemistry, catalysis, use of ionic solvents, etc. are examples of those methods. Among the biological activities pursued by the proposed synthetic methods are those leading to antivirals, antineoplastic and antibiotic agents. Nevertheless, the synthesized sort of compounds allows the search for another interesting activities like those related with autoimmune diseases (rheumatoid arthritis, Chron, etc.) or metabolic dysfunctions (diabetes, etc.).

Publicaciones: P. Merino, J. Revuelta, T. Tejero, U. Chiacchio, A. Rescifina, G. Romeo. A DFT study on the 1,3-dipolar cycloaddition reactions of C-(methoxycarbonyl)-N-methyl nitrone with methyl acrylate and vinyl acetate. Tetrahedron 2003, 53, 3581-3592. P. Merino, S. Franco, D. Lafuente, F. Merchan, J. Revuelta, T. Tejero. Stereoselective synthesis of (-)-Deacetylanisomycin. Eur. J. Org. Chem. 2003, 2877-2881.

P. Merino. Heterocyclic Nucleosides. Chemical synthesis and biological properties. Curr. Med. Chem. 2002, 1, 389-411. Proyectos: Síntesis asimétrica de análogos de nucleósidos (BQU2001-2428). Síntesis de agroquímicos modernos de especialidad para incidir en algunos parámetros de calidad de exportación en los frutos (PROFIT-040000-2001-53). Miembros del ICMA que participan en esta línea: P. Merino, T. Tejero, S. Franco, F. L. Merchán, J. A. Matés, V. Mannucci, J. I. Delso, P. Romero

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2.1.2.- Ciencia y Tecnología de Materiales

Materials Science and Technology

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Propiedades ópticas lineales y no lineales de moléculas y polímeros orgánicos. Una de nuestras líneas de investigación es el estudio de las propiedades ópticas de polímeros, tanto cristales líquidos (CLs) como amorfos para aplicaciones ópticas, fundamentalmente en el campo del almacenamiento óptico de información. Uno de los objetivos es obtener películas de polímeros con buenas características ópticas y cuyas propiedades puedan modificarse ópticamente de forma controlada. En particular, la presencia de grupos azobenceno, cuya orientación es foto controlable, permite acceder a dispositivos para almacenamiento digital y holográfico de información. Un aumento espectacular de la capacidad de almacenamiento se espera de la holografía de volumen. La necesidad de disponer de películas gruesas ha forzado el diseño de nuevos materiales de partida. En particular, se ha propuesto la utilización de polímeros bloque, en los que las unidades fotocrómicas estén agrupadas en dominios (de escala nanoscópica) separados unos de otros; esto permite conservar la capacidad auto organizativa de los CLs evitando los problemas de dispersión de luz y de absorción asociada a elevadas concentraciones de azobenzeno. La búsqueda de materiales para aplicaciones ópticas no lineales exige la caracterización de las unidades básicas responsables de la respuesta no lineal (los cromóforos) y la profundización en el estudio de las relaciones estructura molecular-no linealidad. En este campo, unos materiales muy atractivos son los polímeros a los que se incorporan moléculas no lineales. El estudio de su respuesta no lineal en función de la composición y procesado completa esta línea de investigación.

Optical Properties of organic molecules and polymers. We are working on the study of optical properties of liquid crystalline and amorphous polymers for optical applications, mainly in the field of optical storage. One of the aims is to obtain polymeric films with good performances which optical properties can be modified with light. In particular, the incorporation of azobenzene groups and the photo control of their orientation allow us to design optical devices for digital and holographic storage. An enhancement of the storage capacity is expected using volume holography techniques. New materials must be designed in order to prepare the required thick films. In particular the use of block polymers has been proposed. In these systems, the photo chromic units are grouped (nanoscopic scale); the self-organizing ability of LC polymers is guaranteed but the scattering and absorption effects decrease. The search of materials for non-linear optical applications requires the characterization of non-linear chromophores and the deep study of the molecular structure-non linearity relationships. In this field, the most interesting bulk organic materials are polymers with non-linear moieties. The study of their non-linear response as a function of the composition and processing conditions is other of our research lines.

Publicaciones C. Sánchez, R. Alcalá, S. Hvilsted, P. S. Ramanujam. Effect of heat and film thickness on a photoinduced phase transition in azobenzene liquid crystalline polyesters. J. App. Phys 2003, 93, 4454-4460.

J. L. Díaz, B. Villacampa, F. López-Calahorra, D. Velasco. Synthesis of polyconjugated Carbazolyl-Oxazolones by a tandem hydrozirconation-Erlenmeyer reaction. Study of their hyperpolarizability values. Tetrahedron Lett. 2002, 43, 4333-4337. R. Andreu, J. Garín, J. Orduna, R. Alcalá, B. Villacampa. Novel NLO-phores whit proaromatic Donor and Acceptor groups. Org. Lett. 2003, 5, 3143-3146.

Proyectos Polímeros funcionales para aplicaciones en óptica lineal y óptica no lineal. Proyecto coordinado con el dpto. de Química Orgánica. CICYT (MAT2002-04118-C02-01). Miembros del ICMA que participan en esta línea: R. Alcalá, R. Cases, B. Villacampa.

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Propiedades eléctricas, magnéticas y ópticas de materiales compuestos cerámicos crecidos a partir del fundido Además de sus excelentes propiedades mecánicas, los materiales compuestos cerámicos crecidos a partir del fundido (MGC), también presentan interesantes características funcionales. Hemos investigado algunas de estas posibles aplicaciones funcionales de los materiales cerámicos de composición eutéctica. Por ejemplo, hemos producido láminas delgadas de YBa2Cu3O7-δ y La1-xCaxMnO3-δ con texturas organizadas usando como plantillas superficies escogidas de materiales compuestos de óxidos con estructuras fibrosas o laminares ordenadas. Compuestos laminares de conductores iónicos y aislantes presentan una inusual conducción iónica anisótropa. Hemos producido mazos de fibras ópticas monocristalinas monomodo con densidades de hasta 40000 pixels/mm2 en materiales compuestos de óxidos-fluoruros. CERMETS monolíticos obtenidos de precursores MGC presentan conducción mixta iónica-electrónica. Se está investigando la utilización de algunos de estos CERMETS en ánodos para pilas de combustible. Cuando el tamaño de la fase es comparable al de la longitud de onda emitida la probabilidad de la transición de la misma depende del tamaño característico de la microestructura. Hemos explorado otras aplicaciones tales como las de materiales compuestos ferromagnético-aislante o monocristales con hasta un 50% de poro o fibras monocristalinas de hasta 20 mm de longitud y 1 µm de sección. Como valor añadido a las investigaciones, mencionemos que la mejora en las técnicas de procesado de superficies mediante láser, ha propiciado la contratación de proyectos de desarrollo tecnológico.

Electrical, magnetic and optical properties of melt growth ceramic composites In addition to their excellent mechanical properties, melt growth ceramic composites (MGC) also exhibit interesting functional characteristics. We have explored some of such functional applications of eutectic ceramic composites. For example, we produced patterned YBa2Cu3O7-δ and La1-xCaxMnO3-δ thin films grown on selected surfaces of lamellar or fibrous ordered oxide based composites. Mixed ionic conducting and insulating MGC´s with the lamellar structure presents highly anisotropic ionic conduction. Bunch of single-crystalline single-mode optical fibers with a density up to 40.000 pixels/mm2 were produced in oxide-fluoride composites. Monolithic CERMETS obtained from MGC precursors presented mixed ionic-electronic conductivity. Some of these porous CERMETS can be used as solid oxide fuel cell (SOFC´s) anodes. When the size of the phases is comparable to the emission wavelength their lifetime depends on the microstructure size. Other applications include highly electrically resistive ferromagnetic-insulating composites or 50% volume porous crystals or the production of single crystal fibers up to 20 mm long 1 µm diameter for the first time. As an added value to the proposed investigation, the acquired knowledge of laser-processing procedures has given rise to projects of technological development.

Publicaciones R. I. Merino, J. A. Pardo, J. I. Peña, V. M. Orera. Microstructure size dependence of the 1.520 mm Er3+ luminescence lifetime in Al2O3-ZrO2 eutectic melt growth composites. Appl. Phys. Lett. 2002, 80, 589-591. R. I. Merino, J. I. Peña, A. Larrea, G. F. de la Fuente, V. M. Orera. Melt grown composite ceramics obtained by directional solidification: structural and functional applications. Recent Res. Devel. Mat. Sci. 2003, 4, 1-24. R. I. Merino, J. I. Peña, M. A. Laguna-Bercero, A. Larrea, V. M. Orera. Directionally solidified calcia stabilised zirconia-nickel oxide plates in anode supported solid oxide fuel cells. J. Eur. Ceram. Soc. 2004, 24, 1349-1353. Proyectos Fabricación de materiales funcionales laminares mediante fusión por zonas asistida por láser. (MAT2000-1495). Advanced Ultra-Thin Ceramic Membranes for Efficient Industrial Processes (CERMOX). (CEE GRD-2000-25403). Miembros del ICMA que participan en esta línea: R. I. Merino, J. I. Peña, A. Larrea, M. A. Laguna, V. M. Orera.

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Espectroscopía Raman de materiales de interés tecnológico Se han estudiado mediante Espectroscopía Raman tres tipos de materiales:

− Conductores iónicos para dispositivos electroquímicos tales como baterías de litio y pilas de combustible. Entre otros: perovskitas conductoras de litio de tipo La(2-x)/3LixTiO3 y La0.5(Li,Na)0.5TiO3; bronces protonados HxNa1.2-xNb1.2W0.8O6; óxidos mixtos Zr1-xCexO2. Aspectos estudiados: influencia de tratamientos térmicos en la estructura; orden local; movilidad del litio; inestabilidad AFE; identificación de fases en muestras procesadas mediante láser.

− Nanotubos de Carbono: propiedades físicas básicas, atribución de bandas fonónicas en relación con las relaciones de dispersión del grafito; caracterización de muestras sometidas a diferentes tratamientos con vistas a su utilización como materiales de electrodo en supercondensadores.

− Semiconductores de tipo Zn1-xMnxGa2Se4. Estudio de propiedades físicas a través de su espectro vibracional.

Raman spectroscopy of materials of tecnological interest We have studied with Raman spectroscopy three kinds of materials:

− Ionic conductors for electrochemical devices such as lithium batteries and fuel cells. Among others: lithium-conducting perovskites of type La(2-x)/3LixTiO3 and La0.5(Li,Na)0.5TiO3; protonated bronzes HxNa1.2-xNb1.2W0.8O6; mixed oxides Zr1-xCexO2. Aspects studied are the influence of thermal treatments in the structure, local order, lithium mobility, antiferroelectric instability, and phase identification in laser-processed samples.

− Carbon nanotubes: physical properties, attribution of phononic bands in relation with dispersion relations of graphite; characterisation of samples submitted to different treatments in view of their use as electrode materials in ultracapacitors.

− Semiconductors of type Zn1-xMnxGa2Se4. Study of physical properties through measurement of their vibrational spectrum.

Publicaciones: M. A. Laguna, M. L. Sanjuán, A. Várez, J. Sanz. Lithium dynamics and disorder effects in the Raman spectrum of La(2-x)/3LixTiO3. Phys. Rev. B 2002, 66, 054301-7. M. L. Sanjuán, M. C. Morón. Raman study of Zn1-xMnxGa2Se4 diluted magnetic semiconductors: disorder and resonance effects. Physica B 2002, 316-317C, 565-567. A. Várez, J. Ibarra, A. Rivera, C. León, J. Santamaría, M. A. Laguna, M. L. Sanjuán, J. Sanz. Influence of quenching treatment on structure and conductivity of the Li3xLa2/3-xTiO3 series. Chem. Mater. 2003, 15, 225-232. Proyecto: Materiales conductores iónicos para dispositivos electroquímicos de producción y almacenamiento de energía. MAT2001-3713-C04-02. Miembros del ICMA que participan en esta línea: M. L. Sanjuán, M. A. Laguna, P. Alonso-Gutiérrez.

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Estudio de centros activos radicalarios y metálicos en proteínas redox mediante técnicas avanzadas de EPR Esta línea de investigación se desarrolla en colaboración, cada vez más intensa, con el grupo del Prof. Picorel, de la Estación Experimental de Aula Dei (CSIC), y con el grupo del Prof. Gómez-Moreno del departamento de Bioquímica y Biología Molecular y Celular de la Universidad de Zaragoza. El estudio de la estructura electrónica de estos centros activos en proteínas redox es de gran interés para determinar la relación estructura-función de estos sistemas, los cuáles están involucrados en diversas funciones en los organismos vivos.

Mediante técnicas avanzadas de espectroscopía EPR, especialmente 2D-ESEEM, es posible obtener una información detallada de dicha estructura electrónica; la espectroscopía HYSCORE es una herramienta insustituible a la hora de obtener valores de los tensores de acoplamiento hiperfino y cuadrupolar con los núcleos magnéticos vecinos a la entidad magnética. La información experimental en metaloproteínas se contrasta con la obtenida en compuestos modelo donde, mediante substitución isotópica selectiva, es posible llevar a cabo una asignación directa de las transiciones observadas a núcleos específicos.

La información experimental así obtenida se combina con la suministrada mediante cálculos DFT acerca de la distribución de espín. De esta forma y mediante el estudio de mutantes en los que se sustituyen residuos del entorno del centro activo se obtiene información acerca de la relación estructura-función.

Study of radical and metallic active centers in redox proteins using advanced EPR techniques This research line is developed in cooperation with the prf. Picorel´s team (Estación Experimental de Aula Dei, CSIC) and with prf. Gómez-Moreno´s group (Biochemistry and molecular and cellular biology department of the University of Zaragoza). The study of the electronic structure of these active centers in redox proteins is of great interests in order to determine the structure - function relationship in these systems, which are involved in diverse function of alive organisms.

By advanced EPR spectroscopic techniques, mainly 2D-ESEEM, it is possible to get detailed information about this electronic structure: HYSCORE spectroscopy is an irreplaceable tool for obtaining the hyperfine and quadrupolar coupling tensors with the nuclei near to the magnetic entity. The experimental information on the proteins is compared with that obtain in model compounds where, using selective isotopic substitution, it is possible to assigns the observed transition to specific nuclei.

This experimental information is combined with that about the spin distribution provided by DFT calculation. In this way and by the study of mutants, in which a substitution of residues near to the active center takes place, information about the structure – function is achieved.

Publicaciones: J. I. García, M. Medina, J. Sancho, P. J. Alonso, C. Gómez-Moreno, J. A. Mayoral, J. I. Martínez. A theoretical analysis of the electron spin density distribution of the flavin semiquinone isoalloxazine ring within the protein environment. J. Phys. Chem. A 2002, 106, 4729-4735. I. Yruela, I. García-Rubio, M. Roncel, J. I. Martínez, V. M. Ramiro, J. M. Ortega, P. J. Alonso, R. Picorel. Detergent effect on cytochrome b559 Electron paramagnetic resonance signals in the photosystem II reaction center. Photoch. Photobio. Sci. 2003, 2, 437-442. I. García-Rubio, J. I. Martínez, R. Picorel, I. Yruela, P. J. Alonso. HYSCORE spectroscopy in the cytochrome b559 of photosystem II reaction centre. J. Am. Chem. Soc. 2003, 125, 15846-15854. Proyectos: Estudio, mediante técnicas de resonancia paramagnética electrónica en onda continua y en el dominio temporal, de citocromos de la cadena de transporte electrónico fotosintético (CONSI+D, DGA P111/2001). Versatilidad del anillo de isoaloxazina como centro redox. Implicaciones en procesos de transferencia de electrones entre proteínas (MCYT BQU2001-2520/). Mecanismos moleculares de toxicidad y tolerancia inducidos por cobre en el aparato fotosintético de plantas superiores. Un estudio en suspensiones de células fotosintéticas de soja como organismo modelo (CONSI+D, DGA P015/2001). Miembros del ICMA que participan en esta línea: P. J. Alonso, J. Martínez.

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Óxidos de metales de transición: Síntesis, caracterización y técnicas de radiación de sincrotrón. La actividad realizada en el estudio de óxidos de metales de transición se puede resumir en los siguientes puntos: i) Síntesis, caracterización estructural y magnética de óxidos mixtos de Mn conocidos como manganitas. En concreto se estudió el efecto del desorden en el material magnetorresistivo La2/3Sr1/3MnO3, donde se observó un desacoplo de las transiciones magnética y eléctrica que ha sido caracterizado y explicado. Se estudió la serie LaMn1-xMgxO3 donde se ha establecido la existencia de un orden de largo alcance entre el Mn y el Mg. Las propiedades magnéticas se explican por el cambio de valencia del Mn y el efecto de la dilución ii) Preparación, caracterización estructural y magnética de óxidos usados en los puntos iii) y iv) junto con materiales conocidos como "perovskitas dobles". Este estudio se realiza en colaboración con el departamento de magnetismo del ICMA y se centra en compuestos tipo A2MM'O6 (A=alcalino-térreo; M=Fe, Cr; M'=Mo, Re) de gran interés por sus aplicaciones en espintrónica. Hemos optimizados los métodos sintéticos obteniéndo materiales con buena respuesta a campos magnéticos bajos y compuestos con los altos campos coercitivos (óxidos de Re). iii) Uso de radiación de sincrotrón en el ESRF. En concreto, a) experimentos de espectroscopia de absorción de rayos X en cristales crecidos en nuestro laboratorio de La1.5Sr0.5MnO4. b) Experimentos de difracción anómala o resonante en el Fe3O4. c) Experimentos de dispersión de neutrones en el ILL. iv) Entre todos los trabajos, quisiéramos resaltar: a) El estudio realizado sobre la transición de fase en el LaMnO3 (compuesto base de las manganitas magnetorresistivas) ha clarificado el papel de la distorsión Jahn-Teller en las propiedades de estos materiales. b) La investigación del ordernamiento de carga en la magnetita (transición de Verwey) y en las manganitas ha permitido establecer la ausencia de ordenamiento iónico en estos materiales.

Transition metal oxides: Sintesis, characterization and synchrotron radiation techniques. The activity carried out in the study of transition metal oxides can be summarized as follows: i)Synthesis, structural and magnetic characterization of the mixed oxides of Mn, the so-called manganites. In particular, we studied the effects of disorder in the properties of La2/3Sr1/3MnO3. We found that magnetic and electrical transitions were non-coupled in some compounds. Such a behaviour was characterized and explained. We also studied the LaMn1-xMgxO3 series. A long range Mn/Mg ordering was found. The magnetic properties along the series were accounted for by the continuous change of the Mn valence and the dilution effect by a non-magnetic ion. ii) Synthesis, structural and magnetic characterization of the oxides used in the points iii) and iv) together with materials denoted as “double perovskites”. This study is performed in collaboration with the department of magnetism in the ICMA. It is focused in the A2MM'O6 compounds (A=Ba, Sr, Ca; M=Fe, Cr; M'=Mo, Re) that are very promising for spintronic applications. We have improved synthetic routes to otain materials with a good response to low magnetic fields. In addition, we have found new samples showing either new transitions or new properties such as large coercive fields (Re based oxides). iii) Syncrotron radiation experiments at the ESRF in Grenoble. a) X-ray absorption spectroscopy studies in single crystals of La1.5Sr0.5MnO4 grown in our laboratory. b) Resonant scattering experiments in magnetite. c) Neutron diffraction experiments at the ILL. iv) Among our scientific results, the most stricking points are: a) the study of the phase transition at high temperature of LaMnO3 (mother compund for magnetoresistive manganites) has clarified role of Jahn-Teller distortion in the properties of these materials. b) The research on the charge ordering in magnetite (Verwey transition) and manganites has allowed us to establish the lack of ionic ordering in these materials in opposite to the previous believings.

Publicaciones: M. C. Sánchez, G. Subías, J. García, J. Blasco. The cooperative Jahn-Teller phase transition in LaMnO3 studied by x-ray absorption spectroscopy. Phys. Rev. Lett. 2003, 90, 045503. J. Blasco, J. García, J. Stankiewicz. Effects of Ga doping in La2/3Sr1/3MnO3. Phys. Rev. B 2003, 68, 054421. J. Blasco, C. Ritter, L. Morellón, P. A. Algarabel, J. M. de Teresa, D. Serrate, J. García, M. R. Ibarra. Structural, magnetic and transport properties of Sr2Fe1-xCrxMoO6. Solid State Sciences 2002, 4, 651-660. Proyectos: Estudio de óxidos de valencia mixta y nanoestructuras de semiconductores: Síntesis, caracterización y aplicación de las espectroscopias de rayos X (MAT2002-01221). Síntesis y crecimiento cristalino de materiales magnetorresistivos. Estudio mágnetico, eléctrico, estructural y electrónico (MAT99-0847). Miembros del ICMA que participan en esta línea: J. García, J. Blasco, G. Subías, M. C. Sánchez, M. G. Proietti, J. Herrero.

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Desarrollo de la espectroscopía de absorción de rayos-x y nuevas técnicas emergentes basadas en la radiación de sincrotrón Esta línea de investigación está encaminada al desarrollo de la espectroscopía de absorción de rayos-x y técnicas asociadas como herramientas de caracterización de materiales. Para ello, nuestra actividad se centra por un lado en la demostración de la viabilidad de la técnica XANES como sonda estructural. Para ello, se realizan cálculos desde primeros principios de espectros de absorción de rayos-x sin la intervención de ningún parámetro libre o proceso de refino. Por otra parte, intentamos establecer los límites de aplicabilidad del dicroísmo magnético circular en la absorción de rayos-x circular (XMCD) como herramienta de caracterización magnética de materiales. En particular, nuestra investigación se centra en la aplicación de esta técnica al estudio del magnetismo de materiales intermetálicos de tierra-rara y metal de transición. Nuestro objetivo último consiste en obtener la caracterización magnética de los estados 5d y 4f del metal lantánido como paso previo a la modelización de la interacción magnética entre la tierra rara y el metal de transición.

Development of x-ray absorption spectroscopy and new synchrotron radiation related techniques. This research line is devoted to the development of x-ray absorption spectroscopy and its related techniques as tools for materials characterization. Our activity is focussed, on the one hand, into demonstrating the capability of XANES as a structural tool. To this aim we perform ab-initio calculations of x-ray absorption spectra without using any free parameter or fitting procedure. On the other hand, we try to determine which are the limits of x-ray magnetic circular dichroism (XMCD) to be used as a materials characterization tool. In particular our XMCD research is focussed into the study of magnetism in rare-earth transition metal intermetallic materials. Our aim to get the magnetic characterization of both the 5d and 4f states of the lanthanide metal as the first step to modelize the magnetic interaction between the rare-earth and the transition metal.

Publicaciones: J. Chaboy, E. Cotallo, S. Quartieri, F. Boscherini. New opportunities in trace elements structural characterization: High-energy X-ray absorption near-edge structure spectroscopy. J. Syncrotron Radiat. 2002, 9, 86-89. J. Chaboy, C. Piquer. Modification of the magnetic properties of the R2Fe14B series (R= rare-earth) driven by hydrogen absorption. Phys. Rev. B 2002, 66, 104433. J. Chaboy, C. Piquer, N. Plugaru, H. Maruyama, N. Kawamura, M. Suzuki. Relationship between hydriding and Nd magnetic moment in Nd2Fe14B. J. Appl. Phys. 2003, 93, 475. Proyectos: Materiales Magnéticos avanzados: síntesis, caracterización y aplicaciones (MAT99-0667-C04-04). Desarrollo de nuevos materiales magnéticos de alto interés tecnológico: nuevas rutas de síntesis y de caracterización microscópica (DGA-P004/2001). Caracterización y aplicaciones de nuevos materiales nanoestructurados magnéticos (MAT2002-04178-C04-03). Magnetismo y Radiación de Sincrotrón, Acuerdo de cooperación CICYT-INFN, CICYT. Miembros del ICMA que participan en esta línea: J. Chaboy, M. A. Laguna, C. Piquer

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Nanoestructuras de semiconductores y técnicas espectroscópicas con radiación de sincrotrón El objetivo de esta línea de investigación es la caracterización mediante espectroscopía de absorción de rayos-X (EXAFS, XANES) y difracción anómala de rayos-X (DAFS), de hilos y puntos cuánticos (QWrs, QDs) autoorganizados de semiconductores III-V. Estos materiales, que presentan nuevas propiedades asociadas a los efectos cuánticos de confinamiento de los portadores, constituyen la base de los nuevos dispositivos electrónicos y optelectrónicos y de la tecnología de las telecomunicaciones. El conocimiento detallado de su estructura local, es decir el estado de tensión, las propiedades elásticas, la composición, es de fundamental importancia para la comprensión y la mejora de sus propiedades físicas. Se realizan medidas de difracción anómala y absorción en incidencia rasante (GIDAFS, GIXAFS), de hilos cuánticos de InAs crecidos de forma autoorganizada por epitaxia de haces moleculares (MBE) en sustratros de InP(001). Se estudian también puntos cuánticos de GaN/AlN crecidos mediante técnica Stranski-Krastanov modificada, sobre sustratos de SiC. El objetivo es obtener un mapa el estado de tensión y la composición de las nanoestructuras. Esta línea de investigación se está desarrollando en colaboración con el laboratorio SP2M del CEA (Commissariat à l'Energie Atomique) de Grenoble y es objeto de una acción integrada hispano francesa (MCYT). Las muestras se fabrican en el laboratorio MBE del CEA de Grenoble y en el Instituto de Microelectrónica de Madrid. Los últimos resultados obtenidos en los QWrs de InAs han sido objeto del ESRF Highlights 2003 y están en via de publicación en el Physical Review Letters.

Synchrotron radiation spectroscopy of semiconductor nanostructures. The aim of this research activity is to characterize, by means of X-ray absorption spectroscopy (EXAFS, XANES) and Anomalous Diffraction X-ray spectroscopy (DAFS), self-assembled semiconductor Quantum Dots (QDs) and Quantum Wires (QWrs). These materials provide new physical properties related to the carriers confinement at a quantum size scale and they are the base of the novel electronic and optoelectronic devices for telecommunications. A detailed knowledge of their local structural properties, i.e. lattice strain, elastic properties, size, composition etc., is of major importance to better understand and improve their physical properties. We carry out X-ray anomalous diffraction and absorption, in the grazing angle geometry (GIDAFS; GIXAFS), of auto-organized InAs QWrs grown by Molecular Beam epitaxy (MBE) onto InP(001) substrates. We also study GaN/AlN QDs, grown by MBE modified Stranski-Krastanow technique, onto SiC substrates. Our goal is to obtain a map of the nanostructures strain and composition. This research activity is being developed in collaboration with the SP2M group of CEA (Commissariat à l'Energie Atomique) of Grenoble and is supported by a French-Spanish agreement (MCYT). The samples are grown in the MBE laboratories of CEA in Grenoble and of the Instituto de Microelectrónica in Madrid. The last results obtained on the InAs Qwrs have already appeared as EFSR Highlights 2003 and are in press on Physical Review Letters.

Publicaciones: S. Grenier, M. G. Proietti, H. Renevier, L. González, J. M. García, J. García. Grazing incidence diffraction anomalous fine structure of InAs/InP(001) self-assembled quantum wires. Europhys. Lett. 2002, 57, 499. H. Renevier, S. Grenier, S. Arnaud, J. F. Bérar, B. Caillot, J. L. Hodeau, A. Letoublon, M. G. Proietti, B. Ravel. Diffraction anomalous fine-structure spectroscopy at beamline BM2 at the european Synchrotron radiation facility. J. Syncrotron Radiat. 2003, 10, 435. H. Renevier, M.G. Proietti, S. Grenier, G. Ciatto, L. González, J. M. García, J. M. Gérard, J. García. Glancing angle EXAFS of encapsulated self- assembled InAs/InP quantum wire and InAs/GaAs Quantum Dots. Mat. Sci. Eng. 2003, 101, 174. Proyectos: Estudio de óxidos de valencia mixta y nanoestructuras de semiconductores: Síntesis, caracterización y aplicación de las espectroscopias de rayos X (MAT2002-01221). Síntesis y crecimiento cristalino de materiales magnetorresistivos. Estudio mágnetico, eléctrico, estructural y electrónico (MAT99-0847). Acción integrada hispano-francesa (HF- 2002-0078). Miembros del ICMA que participan en esta línea: M. G. Proietti, J. García.

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Efectos de tamaño en nanoimanes Estudiamos la variación de propiedades físicas de nanomoléculas, partículas o hilos, que contienen entre unos pocos átomos y muchos miles, auto-organizados en retículas de 2- y 3-dimensiones, utilizando nuevas técnicas experimentales desarrolladas ex-profeso para este estudio. Una de las propiedades de mayor interés tecnológico es la anisotropía magnética, puesto que determina la estabilidad de la imanación frente a las fluctuaciones térmicas y, por tanto, si el nanoimán puede actuar o no como unidad de información. Hemos encontrado que la K de nanopartículas de Co aumenta enormemente al disminuir su tamaño. Combinando medidas magnéticas y de dicroismo con radiación de sincrotrón, hemos mostrado que este fenómeno se debe a la no compensación del momento orbital L de los átomos situados en la superficie de las nanopartículas. Además K y L dependen de las propiedades electrónicas (conductor, aislante) de la matríz en la que están embebidas las partículas, abriendo así una vía para aumentar su anisotropía y, por tanto, la densidad de información que estos materiales pueden almacenar. Estudiando multicapas auto-organizadas de estas nanopartículas, hemos encontrado también que la inversión de los momentos magnéticos se ralentiza a medida que aumenta la interacción dipolar magnética con partículas vecinas. Hemos también propuesto un sencillo modelo que da cuenta de los resultados cuantitativamente. Hemos medido los ciclos de histéresis magnética de nanohilos de Fe con diámetro entre 12 y 50 nm a diferentes temperaturas (desde 300 mK) y velocidades de barrido del campo magnético. Para realizar estas medidas utilizamos un sensor micro-Hall, desarrollado en nuestro laboratorio, cuya sensibilidad es ya cuatro órdenes de magnitud mejor que la de un magnetómetro comercial SQUID. Finalmente, hemos contribuido también a investigar el primer cristal de moléculas-imán que se ordena a largo alcance debido a las interacciones dipolares entre moléculas.

Size effects in nanomagnets We study fundamental parameters of nanomagnets containing from a few atoms to a few thousand atoms, self-organized in 2-D and 3-D lattices, often using experimental techniques developed by us to optimise the experiments. The magnetic anisotropy K is one of the magnitudes with highest technological interest, since it determines the stability of the particle magnetic moment against thermal fluctuations, thus also its application in magnetic recording. We have found that K of Co nanoparticles increases enormously as the particle size decreases. By combining magnetic measurements and magnetic dichroism with synchrotron radiation, we have shown this phenomenon to be directly linked to the presence of uncompensated orbital moments L at the particle’s surface. A very interesting discovery is that K and L depend on the electronic properties (insulating or metallic) of the matrix that surrounds the particles, which opens the possibility to tailor their anisotropy, thus also increasing the density of information they are able to store. By studying self-organized arrays of these nanoparticles, we have also found that dipolar interactions with neighboring particles slow down the magnetic relaxation process. We have also proposed a simple theoretical model that quantitatively accounts for these results. We have also measured the magnetic hysteresis loops of magnetic nanowires (between 12 and 50 nm wide) as a function of temperature (from 300 mK) and field sweeping rate. This is done with a micro-Hall magnetometer developed in our laboratory that already has a sensitivity four orders of magnitude better than a commercial SQUID magnetometer. Finally, we have also contributed to the discovery of the first crystal of single-molecule magnets that shows a transition to long-range magnetic order induced solely by the weak dipolar interactions between molecular spins.

Publicaciones: F. Luis, J. M Torres, L. M. García, J. Bartolomé, J. Stankiewicz, F. Petroff, F. Fettar, J. L Maurice, A.Vaurès. Enhancement of the anisotropy of nanometer-sized Co clusters. Phys. Rev. B 2002, 65, 094409. F. Luis, F. Petroff, J. M. Torres, L. M. García, J. Bartolomé, J. Carrey, A. Vaurès. Magnetic relaxation of interacting Co clusters: cross-over from two- to three-dimensional lattices. Phys. Rev. Lett. 2002, 88, 217205; Phys. Rev. Lett. 2002, 90, 059706. A. Morelló, F. L. Mettes, F. Luis, J. F. Fernández, J. Krzystek, G. Aromí, G. Christou, L. J. de Jongh. Long-range ferromagnetic dipolar ordering of high-spin molecular clusters. Phys. Rev. Lett. 2003, 90, 017206. Proyectos: “Imanes Macroscópicos y Nanométricos” de Ministerio de Ciencia y Tecnología (MAT2002-166). Grupo Consolidado IMANA (Departamento de Ciencia, Tecnología y Universidad DGA). Miembros del ICMA que participan en esta línea: J. Bartolomé, F. Luis, L. M. García, F. Bartolomé, J. Stankiewicz, A. Camón, R. López

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Propiedades magnéticas y de transporte eléctrico de intermetalicos de tierra rara y metal de transición Las fases intermetálicas magnéticas de tipo R2Fe14B, R2Fe17 y RFe12-xMx, donde R es una tierra rara y M – metal de transición, son de gran interés tanto para el estudio básico como para la investigación aplicada de imanes permanentes. Hemos estudiado los efectos de introducción de átomos ligeros tales como H, C y N sobre propiedades estructurales y magnéticas de compuestos R2Fe17 y R2Fe14B. Igualmente ha sido investigado el efecto de sustitución parcial de R por un ion nomagnético en Nd2Fe14B. El rol de los estados 5d en intermetálicos RFe11.3W0.7 ha sido determinado mediante espectroscopia Mössbauer y medidas magnéticas. Este estudio ha sido apoyado por cálculo de bandas que aportan los valores esperados de momentos magnéticos y campos hiperfinos en compuestos medidos. Hemos sintetizado y caracterizado estructuralmente y magnéticamente nuevos materials de tipo Rm+nT5m+3nB2n que son imanes permanents con propiedades interesantes. Finalmente, a través de medidas experimentales de la conductividad eléctrica, del efecto Hall y de la imanación, hemos estudiado la interrelación entre transporte electrónico y magnetismo en varios compuestos intermetálicos.

Magnetic and electrical transport properties of rare earth and transition metal intermetallic compounds Intermetallic magnetic phases of type R2Fe14B, R2Fe17 and RFe12-xMx, where R is a rare earth element and M – transition metal atom, are of great interest for basic research as well as for applications as permanent magnets. The effects of interstitials such as H, C and N on structural and magnetic proerties of R2Fe17 and R2Fe14B have been studied. We have also investigated partial substitution of R by nonmagnetic ion in Nd2Fe14B. The role of 5d states in RFe11.3W0.7 intermetallic compounds has been determined by Mössbauer spectroscopy and magnetic measurements. This study has been backed by band calculations which yield values of magnetic moments and hyperfine fields for the alloys studied. We have synthesized and performed structural and magnetic characterization of new materials of type Rm+nT5m+3nB2n, which are attractive as permanent magnets. Finally, electrical conductivity, Hall effect and magnetization measurements enabled us to establish some of reciprocal effects between electronic transport and magnetic state of various intermetallic alloys.

Publicaciones J. Bartolomé, S. Mukherjee, C. Rillo, N. Plugaru, C. Piquer. Magnetic relaxation phenomena in R2Fe17 (R=Y, Dy, Er y Ho) and C and H derivatives. J. Alloy. Compd. 2003, 356-357 C, 208-210. J. Stankiewicz, J. Bartolomé. Magnetic scattering in RMn12-xFex alloys. Phys. Rev. B 2003, 67, 092409.

N. Plugaru, J. Rubín, J. Bartolomé, C.Piquer, M. Artigas. Magnetic properties of RFe11.3W0.7 (R= Dy, Ho, Er and Lu): On the R-Fe exchange inmteraction in the R(Fe,T)12 class of compounds. Phys. Rev. B 2002, 65, 134419. Proyectos: Imanes macroscópicos y nanométricos (MAT2002-166). Motores con imanes permanentes: Optimización dinámica, evaluación de la corrosión de los imanes y nuevos procesos de preparación de materiales para imanes permanentes (MAT2000-0107-P4-02). Estudio de los efectos de la corrosión en imanes permanentes y de las pérdidas ac en cintas e hilos superconductores, mediante la aplicación de campos magnéticos alternos de intensidad media (0,1 T) (DGA PO18/2001). Grupo Consolidado IMANA (Departamento de Ciencia, Tecnología y Universidad DGA). Miembros del ICMA que participan en esta línea: J. Bartolomé, J. Stankiewicz, J. Rubín, A. Camón, N. Plugaru, C. Piquer

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Metrología cuántica Nuestro grupo mantiene una gran tradición en el desarrollo de instrumentación no comercial para su uso en Metrología Cuántica eléctrica. El TPYCEA (Madrid) es el usuario de esta instrumentación que da servicio a la industria española. Durante esta etapa hemos proporcionado al TPYCEA nuevas heteroestructuras de AsGa/AsGaAl caracterizadas a bajas temperaturas (0,3K) y campos intensos (12T) para su uso como patrón primario de resistencia basado en el efecto Hall cuántico. Asimismo hemos optimizado la instrumentación del puente de resistencias basado en el Comparador Criogénico de Corriente: por un lado, se ha diseñado y adquirido un dewar de He de bajo consumo para aumentar el tiempo de autonomía a una semana, por otro lado, se han automatizado las medidas mediante el desarrollo de programas basados en Labview. Un fruto de nuestra colaboración con la universidad de Twente y el laboratorio de metrología nacional holandés (Nmi) ha sido la implementación de un CCC con una relación lo suficientemente elevada (1:30000) como para amplificar la corriente de un dispositivo de ¨Single Electron Tunneling¨. Este sistema ha sido un paso necesario para el desarrollo futuro de un patrón cuántico de corriente.

Quantum metrology Our group has traditionally worked on the development of non-commercial instrumentation for electrical Quantum Metrology. TPYCEA (Madrid) is the user of this instrumentation that provides with a service to the Spanish industry. We have supplied TPYCEA with characterized AsGa/AsGaAl heteroestructures at 0.3K up to 12T; they will be used as primary resistance standard based on the quantum Hall effect. Even more we have optimised the instrumentation of the resistance bridge based on the Cryogenic Current Comparator: on one hand a low consumption cryostat has been designed and purchased, on the other hand labview programs have been developed to automatize the measurements. An achievement of our collaboration with the university of Twente and the national metrology laboratory in The Netherlands (Nmi) has been the implementation of a CCC with a sufficient relation (1:30000) for the amplification the current of a Single electron Tunneling device. This system has been a necessary step towards the development of a quantum current standard.

Publicaciones G. Rietveld, E. Bartolomé, J. Sesé, P. de la Court, J. Flokstra, C. Rillo, A. Camón. 1:30.000 cryogenic current comparator with optimum squid readout. IEEE T. Instrum. Meas. 2003, 52, 621-625. C. Rillo, J. Sesé, E. Bartolomé, J. Flokstra, A. Camón, G. Rietveld. On the sensitivity of cryogenic current comparators: theory and experiments. Metrologia 2003 40, 51-56. J. Sesé, E. Bartolomé, A. Camón, J. Flokstra, G. Rietveld, C. Rillo. Simplified calculus for the design of a cryogenic current comparator. IEEE T. Instrum. Meas. 2003, 52, 612-616. Proyectos: Optimización y automatización de dos comparadores criogénicos de corriente (OTRI2003/366).

Miembros del ICMA que participan en esta línea: C. Rillo, A. Camón, J. Sesé.

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Simulaciones de sistemas magnéticos Clusters magnéticos, como Fe8 y Mn12, que constituyen los núcleos de moléculas organometálicas, se comportan a bajas temperaturas como grandes espines da magnitud dada. En cristales, a baja temperatura, la relajación magnética sólo puede ocurrir por medio del efecto túnel. Surge la pregunta de si puede haber relajación hasta llegar al orden magnético. La respuesta es afirmativa, aunque a tasas de relajación que disminuyen como la potencia cúbica de la fracción de la desviación típica de los campos dipolares cubierta por la ventana abierta al efecto túnel. Además, se ha elaborado una teoría para la relajación anómala, que estaba sin explicar. Se predice que la relajación: (a) está controlada por el protocolo de enfriamiento previo a la relajación; (b) está dirigida por la entropía (no por la energía); (c) Evoluciona como la potencia p del tiempo, siendo p=1/2, para Fe8, pero no así en general; (d) la relajación cesa una vez que todos los espines se han invertido por lo menos una vez, mucho antes de alcanzar el equilibrio térmico.

Simulations of magnetic systems Magnetic clusters, such as Fe8 and Mn12, that make up the core of large organometallic molecules, behave at low temperatures as large single spins. In crystals, their magnetic relaxation can only take place through magnetic quantum tunneling, at very small temperatures. The question arises whether crystals of such tunneling dipoles can relax all the way into a magnetically ordered state. We have found that this does indeed apeen, albeit at a rate that vanishes as the cube of the fraction of the root mean square of the dipolar fields that is covered by the tunneling window. In addition, a theory for the previously unexplained anomalous relaxation of Fe8 has been developed. It predicts the relaxation: (a) is controlled by the cooling protocol; (b) is entropy (not energy) driven; (c) evolves a the p–th power of time, where p=1/2 for Fe8, but not so in general; (d) the relaxation stops when all spins in the system have flipped at least once, long before equilibrium ensues.

Publicaciones J. F. Fernández. Dipolar ordering of molecular magnetic clusters. Phys. Rev. B 2002, 66, 064423 . J. F. Fernández. Simulation of quantum tunneling in an open system. Modeling of Complex Systems: Seventh Granada Lectures, edited by J. Marro and P. Garrido (American Institute of Physics, N.Y., 2003) pp. 242-250. J. F. Fernández, J. J. Alonso. Magnetization of single molecule magnets. Phys. Rev. Lett. 2003 91, 047702. Proyectos: Relajación magnética cuántica y diagrama de fases de sistemas de moléculas imán. (BFM2003-03919-C02-01) Miembros del ICMA que participan en esta línea: J. F. Fernández

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Materiales moleculares magnéticos Esta línea se centra en el estudio del comportamiento físico de materiales magnéticos constituídos por moléculas magnéticas o que contengan un sustrato molecular o polimérico que contribuya a configurar las propiedades del material. De forma primordial interesa el estudio de materiales constituídos por radicales libres, los formados por moléculas de alto espín y el de materiales con propiedades multifuncionales, ópticas, magnéticas y eléctricas, tales que permitan comportamientos opto-magnético, magneto-resistivo, etc. Entre los materiales que se vienen estudiando caben destacar compuestos radicalarios basados en azufre, en cuyo estudio este grupo es pionero, complejos radicalarios con metales de transición, compuestos de coordinación con equilibrio alto espín-bajo espín y líquidos orgánicos paramagnéticos. El grupo utiliza, de manera habitual, una gran variedad de técnicas: térmicas, estructurales, magnéticas, grandes instalaciones para experimentos basados en dispersión de neutrones o implantación de muones, técnicas de presión, opto-magnética, etc. Cuando el alto grado de innovación, o la novedad, de una técnica hacen que no existan instrumentos comerciales, éstos se desarrollan en el propio grupo. Los objetivos concretos son los siguientes:

− Búsqueda de nuevos imanes orgánicos con temperaturas en la región del nitrógeno líquido o superiores, donde los radicales basados en azufre reciben un interes prioritario.

− Identificación de materiales moleculares susceptibles de modificar su ordenamiento magnético mediante foto-excitación.

− Orden magnético en moléculas de alto espín. − Estudio y caracterización de materiales

moleculares multifuncionales, en particular imanes quirales.

− Preparación, estudio y desarrollo de nanocomposites magnéticos poliméricos de interés aplicado.

Magnetic molecular materials This research line is centered on the study of the physical behavior of magnetic materials formed by either molecules or a polymeric substrate which in either case contributes to the material properties. Of primary interest is the study of materials formed by free radicals, high spin molecules and materials with multifunctional properties, e.g. optic, magnetic and electric, thus presenting behavior such as opto-magnetic, magneto-resistive and other. Materials currently investigated include sulfur-based free radical compounds, in which study the group is a recognized pioneer, organic radical-based transition-metal compounds, transition compounds with high spin-low spin equilibrium and paramagnetic organic liquids. The research is carried on using a rather large variety of physical techniques. The list includes thermal, structural and magnetic techniques, the use of large facilities for neutron scattering and muon implantation experiments, and pressure, photomagnetic and magneto-optic techniques. The Group also develops its own technical equipment when it is not commercially available due to its novelty or innovation degree. The following are specific goals:

− Search of new organic, metal-free, magnets with ordering temperatures in the region of liquid nitrogen and above, where S-based organic radicals receive prioritary interest.

− Characterization of molecular materials that modify their magnetic ordering under photo-excitation.

− Magnetic ordering in high spin molecules. − Study and characterization of multifunctional

molecular materials, particularly quiral magnets. − Preparation, study and development of polymer

magnetic nanocomposites of applied interest.

Publicaciones A. Alberola, R. J. Less, C. M. Pask, J. M. Rawson, F. Palacio, P. Oliete, C. Paulsen, A. Yamaguchi, R. D. Farley. A thiazyl-based organic ferromagnet. Angew. Chem. Int. Ed. 2003, 42, 4782-4785. N. Moliner, L. Salmon, L. Capes, M. C. Muñoz, J. F. Létard, A. Bousseksou, J. P. Tuchagues, J. J. McGarvey, A. C. Dennis, M. Castro, R. Burriel, J. A. Real. Thermal and optical switching of molecular spin states in the FeL[H2B(pz)2]2 spin crossover system (L=bpy, phen). J. Phys. Chem. B 2002, 106, 4276-7283. J. Campo, J. Luzón, F. Palacio, A. Millán, G. J. McIntyre. Superexchange interaction enhanced through spin delocalization in Rb

2FeBr

5.H

2O as studied by polarized neutron diffraction. Polyhedron 2003, 22, 2297-2299.

I. Gilbert, A. Millan, F. Palacio, A. Falqui, E. Snoeck, V. Serin. Magnetic properties of maghemite nanoparticles in a polyvinylpyridine matrix. Polyhedron 2003, 22, 2457-2461. Proyectos: Molecular magnetism: from materials towards devices (TMR Network ERBFMRXCT980181). Materiales moleculares magnéticos. Comportamiento magnético de materiales moleculares y poliméricos. CICYT, (MAT2000-1388-C03-03). Materiales magnéticos funcionales: materiales moleculares y materiales intermetálicos. (MAT2001-3507-C02-02). Síntesis y propiedades físicas de nanoimanes unimoleculares obtenidos mediante nuevos métodos de síntesis (Proyecto CTP2002/REDES). Nanoimanes moleculares (MAT2002-00433). Miembros del ICMA que participan en esta línea: R. Burriel, J. Campo, M. Castro, J. L. Luzón, A. Millán, M. C. Morón, F. Palacio, A. Rodríguez, A. Urtizberea.

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Propiedades térmicas de materiales La respuesta de materiales al suministro de calor se manifiesta, por una parte, en magnitudes estáticas que dan cuenta del almacenamiento de esa energía y se describen con variables termodinámicas como el calor específico. Por otra parte, su propagación viene caracterizada por la conductividad térmica. Hemos desarrollado técnicas especiales de calorimetría para el estudio de materiales: calorimetría con fotoexcitación, con campo magnético y en función de la orientación cristalina, efecto magnetocalórico en condiciones adiabáticas, microcalorimetría de modulación y de relajación. Los trabajos se centran en efectos termodinámicos y transiciones de fase en materiales moleculares magnéticos, materiales intermetálicos, imanes duros, aislantes magnéticos y cerámicas. Se estudian también transiciones estructurales, procesos de orden-desorden y su relación con la estructura cristalina. La conductividad térmica se estudia en cerámicas superconductoras de alta temperatura y materiales de interés tecnológico. Entre los objetivos, se pretende determinar termodinámicamente los procesos de ordenamiento y transiciones en materiales magnéticos. Esto permite deducir las interacciones y predecir su aptitud para desarrollos tecnológicos. También se obtiene la caracterización energética de materiales en los que se pueden sintonizar varias funciones interactuantes: magnética, eléctrica, óptica, estructural y térmica. En concreto, se aplica a problemas de:

- Refrigeración magnética a temperatura ambiente.

- Activación óptica de estados magnéticos. - Marcadores térmicos de estados biestables. - Inducción de orden mediante luz, presión o

campo magnético.

Thermal properties of materials The behaviour of materials upon the application of heat is given by static magnitudes that take into account the energy storage and are described by thermodynamic variables like the specific heat. On the other side, the heat propagation is characterised by the thermal conductivity. We developed special calorimetric techniques for the study of materials: calorimetry under photo-excitation, in the presence of applied magnetic fields and with varying crystal orientation, magnetocaloric effect in adiabatic conditions, modulation and relaxation microcalorimetry. Of primary interest are thermodynamic effects and phase transitions in molecular magnetic materials, intermetallic materials, hard magnets, magnetic insulators and ceramic materials. Structural phase transitions, order-disorder processes and their relation with the crystal structure are also investigated. Thermal conductivity is studied in high Tc superconducting ceramics and other materials of strong technological interest. Among the goals we try to obtain the thermodynamic determination of ordering processes and transitions in magnetic materials. It allows the deduction of the interactions and their suitability for technical developments. Also the energetic characterization of materials where several interacting functions can be tuned: magnetic, electric, optic, structural and thermal. In particular they include:

- Magnetic refrigeration at room temperature. - Photo-activation of magnetic states. - Thermal indicators of bi-stable states. - Ordering induction with light, pressure, or

magnetic field.

Publicaciones N. Moliner, L. Salmon, L. Capes, M. C. Muñoz, J. F. Létard, A. Bousseksou, J. P. Tuchagues, J. J. McGarvey, A. C. Dennis, M. Castro, R. Burriel, J. A. Real. Thermal and optical switching of molecular spin states in the FeL[H2B(pz)2]2 spin crossover system (L=bpy, phen). J. Phys. Chem. B 2002, 106, 4276-7283. M. C. Gallardo, R. Burriel, F. J. Romero, F. J. Gutiérrez, E. K. H. Salje. Low-temperature calorimetric study of SrTiO3. J. Phys. Condens. Mat. 2002 14, 1881-1886. R. Burriel, E. Palacios, J. J. Melero, P. Ferloni. Orientational phase transition of (CH3)4NCIO4 in two and three dimensions. Ferroelectrics 2002, 270, 393-398. Proyectos: Materiales magnéticos funcionales: materiales moleculares y materiales intermetálicos. (MCYT MAT2001-3507-C02-02). Phonon spectra, thermodynamic stability and phase transitions in perovskite-like crystals. (INTAS, RFBR-97-10177). Caracterización del proceso de polimerización de pastas resistivas mediante calorimetria diferencial de barrido y correlación con medidas eléctricas. (OTRI 2002-0297 con la empresa ACP S.A.)

Miembros del ICMA que participan en esta línea: R. Burriel, M. Castro, F. Palacio, E. Palacios, A. Rodríguez, L. Tocado.

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Estudio de sistemas de alto interés en magnetoelectrónica Una línea de investigación central dentro del área de los materiales magnetoelectrónicos es la de los sistemas magnetorresistivos, de aplicación en lectura de información almacenada magnéticamente, en sensores de campo magnético, en memorias no volátiles, en potenciómetros de no contacto, etc. A continuación, enumeramos los sistemas magnetorresistivos más interesantes que estamos estudiando: - Óxidos de manganeso que presentan magnetorresistencia colosal: nuestro estudio se focaliza en la investigación de la relevancia de la segregación de fases nanoscópica y microscópica en el fenómeno de magnetorresistencia colosal. - Dobles perovsquitas de alta temperatura de Curie y polarización de espín: intentamos obtener compuestos que muestren una elevada magnetorresistencia a bajo campo hasta 200ºC (temperatura máxima de trabajo de los dispositivos en los que se pretenden aplicar) y comprender los mecanismos que determinan la temperatura de Curie, la magnetorresistencia y los fenómenos magnetoestructurales. - Uniones túnel magnéticas: investigamos los parámetros que controlan la magnetorresistencia túnel en este tipo de dispositivos. - Partículas magnéticas nanométricas encapsuladas en materiales orgánicos y otras matrices: queremos conseguir el encapsulado efectivo de partículas nanométricas magnéticas en diferentes matrices para estudiar su respuesta magnetorresistiva y su comportamiento magnético. - Composites de partículas magnéticas y polímeros: fabricamos composites de fácil procesabilidad y compatibles con la tecnología actual en la industria de los potenciómetros buscando efectos de elevada magnetorresistencia a bajo campo hasta 200ºC.

Study of systems of high interest in magnetoelectronics A central research line in the area of the magnetoelectronic materials is that of magnetoresistive systems, of wide application in the reading of information stored magnetically, in magnetic sensors, in non-volatile memories, in contact-less potentiometers, etc. In the following, we cite the most interesting magnetoresistive systems currently studied by us: - Manganese oxides showing colossal magnetoresistance: our study focuses on the relevance of the nanoscopic and microscopic phase segregation to the colossal magentoresistance phenomena. - Double perovskites with high Curie temperature and spin polarization: we are trying to obtain compounds exhibiting high magnetoresistance ratios at low magnetic fields up to 200ºC (maximum working temperature of the devices where they will be used) and understand the mechanisms that determine the Curie temperature, the magnetoresistance and the magnetostructural phenomena. - Magnetic tunnel junctions: we investigate the parameters that control the tunnel magnetoresistance in this type of devices. - Magnetic particles encapsulated in organic materials and other matrices: we want to obtain the effective encapsulation of nanometric magnetic particles in different matrices in order to study the magnetoresistive response and their magnetic behaviour. - Composites of magnetic particles and polymers: we obtain composites easy to process and compatible with the current technology in the industry of potentiometers that show high magnetoresistance ratios at low magnetic fields up to 200ºC as well as understand the mechanisms controlling the magnetotransport.

Publicaciones: J. M. de Teresa, M. R. Ibarra, P. A. Algarabel, L. Morellón, B. García-Landa, C. Ritter, A. Maignan, C. Martin, B. Raveau, A. Kurbakov, V. Trounov. Magnetic versus orbital polarons in colossal magnetoresistance manganites. Phys. Rev. B Rapid Communications 2002, 65, 100403. D. Serrate, J. M. de Teresa, J. Blasco, M. R. Ibarra, L. Morellón, C. Ritter. Large low-field magnetoresistance and TC in polycrystalline (Ba0.8Sr0.2)2-xLaxFeMoO6 double perovskites. Appl. Phys. Lett. 2002, 80, 4573. C. Martínez-Boubeta, J. M. de Teresa, J. L. Costa-Kramers, A. Cebollada, J. A. Anguita, F. Briones, D. Serrate, J. I. Arnaudas, M. R. Ibarra. Magnetic coupling in epitaxial in TM/MgO/Fe(001) (TM=FeCo, Fe/Co, Fe) macroscopic and microscopic trilayers. J. Appl. Phys. 2003, 94, 4006. Proyectos: Advanced magnetic oxides for responsive engineering (G5RD-CT-2000-00138). Estudio de sistemas magnetorresistivos de alto interés en magnetoelectrónica (MAT2002-04657). Heteroestructuras híbridas con aplicaciones en magnetoelectrónica (MAT-2000-101290-C03-01). Materiales masivos con relevantes propiedades magnetoelectrónicas: intermetálicos y óxidos laminares (MAT-2000-1756). Spin, charge and orbital ordering in complex transition metal oxides: an integrated synthesis and measurement approach (SCOOTMO) (HPRN-CT 2002 00293). Miembros del ICMA que participan en esta línea: M. R. Ibarra, P. A. Algarabel, C. I. Marquina, L. Morellón, J. M. de Teresa, D. Serrate, C. Magén.

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Intermetálicos con propiedades magnéticas relevantes El objetivo de la presente línea de investigación es el estudio de materiales masivos con relevantes propiedades físicas que hagan posible su uso tecnológico. La actividad realizada en este campo se centra fundamentalmente en dos familias de compuestos: TR5(SixGe1-x)4 (TR= Tierra Rara) y Ni2+xMn1+yGa1+z. Ambas series de compuestos presentan transiciones magnéticas y estructurales cuyas temperaturas pueden controlarse a partir de las composiciones relativas de los elementos constituyentes. Cuando las temperaturas de las transiciones magnética y estructural coinciden (transición magneto-estructural de primer orden) es posible, mediante la aplicación de campos magnéticos relativamente débiles, inducir la transición maximizándose en dicho rango de temperaturas propiedades altamente interesantes para una posible aplicación tecnológica de dichos compuestos. Entre dichas propiedades es de destacar la aparición de magnetoestricción, magnetorresistencia y efecto magnetocalórico gigantes. La investigación realizada en nuestro departamento comprende desde la preparación de los intermetálicos mediante fusión en horno de arco hasta su completa caracterización magnética y estructural mediante técnicas macroscópicas (medidas de imanación y susceptibilidad ac, dilatación térmica, resistividad, magnetoestricción y magnetoresistencia) y microscópicas (difracción de rayos X, difracción de neutrones y espectroscopía de muones)

Study of systems of high interest in magnetoelectronics The aim of the research line about the present subject is to study bulk materials with relevant physical properties for technological applications. The research in this field is mainly focused on two series of compounds: RE5(SixGe1-x)4 (RE= Rare Earth) and Ni2+xMn1+yGa1+z. Both series present magnetic and structural transitions at temperatures that can be controlled through the relative composition of the constituent elements. When the transition temperatures of both transformations coincide (first-order magnetostructural transition), it is possible to induce such a transition by applying moderate magnetic fields. By doing so, it is possible to maximize relevant magnetic properties (magnetostriction, magnetoresistance and magnetocaloric effect) for potential technological applications in the selected temperature range. The research performed in our department includes the preparation of the intermetallic samples using an arc furnace, and their complete magnetic and structural characterization by using both macroscopic (magnetization and ac susceptibility, thermal expansion, resistivity, magnetostriction, and magnetoresistance) and microscopic (X-ray and neutron diffraction, and muon spin spectroscopy) techniques.

Publicaciones: C. Ritter, L. Morellón, P. A. Algarabel, C. Magén, M. R. Ibarra. Magnetic and structural phase diagram of Tb5(SixGe1-x)4. Phys. Rev. B 2002, 65, 094405. F. Albertini, L. Pareti, A. Paoluzi, L. Morellón, P. A. Algarabel, M. R. Ibarra, L. Righi. Composition and temperature dependence of the magnetocrystalline anisotropy in Ni2+xMn1+yGa1+z (x+y+z=0) Heusler alloys. Appl. Phys. Lett. 2002, 81, 4032. C. Magén, Z. Arnold, L. Morellón, Y. Skorokhod, P. A. Algarabel, M. R. Ibarra, J. Kamarad. Pressure-induced three-dimensional ferromagnetic correlations in the giant magnetocaloric compound Gd5Ge4. Phys. Rev. Lett. 2003, 91, 2072002. Proyectos: Materiales masivos con relevantes propiedades magnetoelectrónicas: intermetálicos y óxidos laminares (MAT-2000-1756). Miembros del ICMA que participan en esta línea: M. R. Ibarra, P. A. Algarabel, C. I. Marquina, L. Morellón, J. M. de Teresa, D. Serrate, C. Magén.

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Propiedades magnéticas y magnetoelásticas de materiales nanoestructurados. El objetivo de esta línea de investigación es la preparación y estudio de nuevos materiales estructurados, bien en capas delgadas o multicapas, bien como granulares con dimensiones características nanométricas, y cuyas propiedades pueden ser muy diferentes de las observadas en materiales masivos: presencia de anisotropía perpendicular al reducirse el espesor de la capa de un metal magnético 3d o, en el caso de superredes de Tierras Raras y películas epitaxiales, fases magnéticas diferentes de las que existen en los materiales masivos correspondientes y de cambios en la anisotropía magnética. Nuestras medidas de la tensión magnetoelástica en función de la temperatura (300 K- 10 K) realizadas mediante el uso del método “cantilever” indican que la deformación interna es responsable de una contribución adicional a la energía ME. Por ejemplo, en el caso del níquel, el resultado es un incremento en el valor de la coeficiente ME al aumentar la deformación interna. Medidas realizadas en nuestro laboratorio de microscopia de fuerza magnética muestran una fuerte variación, con el espesor de níquel, de la forma y tamaño de los dominios magnéticos, debido a la fuerte variación de la intensidad de la anisotropía perpendicular. Esto se refleja tanto en el proceso de imanación medido mediante magnetometría de muestra vibrante como en el signo y valor de las isotermas de tensión ME.

Magnetic and magnetoelastic properties of nanostructured materials. The aim of this research is the preparation and magnetic characterization of new RE-based materials, structured as thin films, multilayers and granular systems, of nanometric characteristic size, whose properties can be very different from those observed in massive materials: perpendicular magnetic anisotropy in 3d magnetic metals or, for Rare Earth superlattices and thin films, the different found magnetic phases and substantially influences the magnetic anisotropy. Our measurements of the ME stress as a function of the temperature (300 K- 10 K), performed by the cantilever technique, indicate that the internal strain is responsible of an additional contribution to the ME energy. For example for Ni thin films, the issue is that the ME stress coefficient increases as the internal strain increases. Masurements of the magnetic domains performed in our laboratory by magnetic force microscopy show a strong variation of the shape and size of the magnetic domains with the Ni thickness due to the variation of the anisotropy energy. This is also reflected in the magnetization process studied by vibrating sample magnetometry and in the sign and value of the ME stress isotherms measured to determine the magnetoelastic stress.

Publicaciones: M. Ciria, J. I. Arnaudas, L. Benito, C. de la Fuente, A. del Moral, J. K. Ha, R. C. O´Handley. Magnetoelastic effects in thin films with weak out-of-plane anisotropy. Phys. Rev. B 2003, 67, 024429. J. I. Arnaudas, C. de la Fuente, M. Ciria, L. Benito, C. Dufour, K. Dumesnil, A. del Moral. Magnetoelastic stresses in epitaxial (110) Terfenol-D thin films. J. Magn. Magn. Mater. 2002, 240, 389-391. L. Benito, C. de la Fuente, M. Ciria, J. I. Arnaudas, A. del Moral, C. Dufour, K. Dumesnil. Magnetoelasticity of single-crystal (110) SmFe2 thin-film. J. Magn. Magn. Mater. 2002, 242, 1450-1452. Proyectos: Heteroestructuras híbridas con aplicaciones en magnetoelectrónica. (MAT2000-1290-C03-01). Anisotropía magnética y magnetoelasticidad en capas finas de metales de transición. (HF02-167). Magnetismo y magnetoelasticidad en láminas delgadas y en sistemas masivos fuertemente correlacionados. (MAT2003-00893). Miembros del ICMA que participan en esta línea: A. del Moral, J. I. Arnaudas, C. de la Fuente, M. Ciria, L. Benito.

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Compuestos cerámicos de altas prestaciones mecánicas fabricados mediante fusión asistida por láser Los materiales cerámicos de alta resistencia mecánica y tenacidad son de interés en aplicaciones estructurales debido a su ligereza y estabilidad a alta temperatura en atmósferas oxidantes. Estos atributos son especialmente importantes en las turbinas de gas ya que su uso aumenta la eficiencia de la combustión lo que se traduce en un menor consumo y una reducción en emisiones contaminantes. También se aplican en abrasivos, superficies resistentes al desgaste, como refuerzo en materiales compuestos, etc. En esta línea investigamos sobre nuevos compuestos cerámicos que puedan superar las habituales limitaciones de las cerámicas que trabajan a alta temperatura, mejorando su resistencia mecánica, tenacidad y fatiga. Entre los materiales explorados destacan los óxidos eutécticos obtenidos a partir de la solidificación de sus fundidos. El control de la microestructura mediante el procesado nos ha permitido alcanzar valores de resistencia a flexión de hasta 2,3 GPa en el caso de barras eutécticas del sistema Al2O3/Y2O3 (Tm = 1826 ºC), reteniendo dicha resistencia hasta por encima de 1500ºC. También fabricamos laminados cerámicos mediante técnicas de procesamiento cerámico combinadas con tratamientos asistidos por láser para ser aplicados como recubrimientos de substratos metálicos. Utilizamos la fusión superficial por láser de recubrimientos cerámicos fabricados mediante proyección térmica para sellarlos contra la penetración de agentes corrosivos durante el servicio y mejorar la adherencia entre el substrato y el recubrimiento. Las técnicas de caracterización de estos materiales incluyen la microscopía óptica, electrónica, difracción de rayos X, técnicas espectroscópicas (Piezoespectroscopia, Raman) e indentación disponibles en nuestro Instituto mientras que los tests mecánicos se realizan en la Universidad Politécnica de Madrid y la Universidad de Sevilla.

High mechanical performance ceramic composites fabricated by laser assisted solidification Ceramics with high resistance and toughness are of interest for structural applications because of their light weight and high temperature thermodynamic stability even in an oxidant atmosphere. These attributes are of particular importance in gas turbine engines because of the increase in the combustion efficiency and reduction in contaminant emissions. They are also applied as abrasives, wear resistance surfaces, reinforcing fibres, etc. The objective of this line is the development of new ceramic compounds overcoming the current performance limitations for high temperature ceramics, e.g. strength, creep, toughness and fatigue. Among the materials we have explored it is worth mentioning the eutectic oxides obtained from the melt. Tayloring the microstructure by means of the processing conditions allows us to reach strength values of 2.3 GPa for the bars in the eutectic system Al2O3/Y2O3 (Tm = 1826 ºC) retaining this strength up to above 1500 ºC. Layered ceramic composites are produced by ceramic and laser processing to be applied as ceramic coatings on metal substrates. Laser glazing of plasma-sprayed ceramic coatings is another subject of our interest, arising from needs to seal coatings against penetration by corrosive agents during operation and to improve coating-substrate adherence. The characterization procedures involve optical and electronic microscopy, X-ray diffraction, spectroscopic techniques (piezospectroscopy, Raman) and indentation available in our Institute. Mechanical tests are performed in the Universidad Politécnica de Madrid and the Universidad de Sevilla.

Publicaciones N. R. Harlan, R. I. Merino, J. I. Peña, A. Larrea, V. M. Orera, C. González, P. Poza, J. Llorca. Phase Distribution and Residual Stresses in Melt Grown Al2O3-ZrO2 (Y2O3) Eutectics. J. Am. Ceram. Soc. 2002, 85, 2025- 2032. V. M. Orera, R. Cemborain, R. I. Merino, J. I. Peña, A. Larrea. Piezo-Spectroscopy at low Temperatures: Residual Stresses in Al2O3- ZrO2 (Y2O3) Eutectic Measured from 77 to 350 K. Acta Mater. 2002, 50, 4677- 4686. A. Larrea, G. F. de la Fuente, R. I. Merino, V. M. Orera. ZrO2 - Al2O3 eutectic plates produced by laser zone melting. J. Eur. Ceram. Soc. 2002, 22, 191-198. Proyectos Procesado por láser de cerámicos estructurales avanzados. (P3)( MAT2000-1533-C03-02). Miembros del ICMA que participan en esta línea: J. I. Peña, A. Larrea, R. I. Merino, V. M. Orera, G. F. de la Fuente, C. Diez, I. de Francisco, P. B. Oliete.

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Aplicaciones del láser en la transformación y modificación de materiales. El objetivo fundamental del grupo es utilizar las ventajas que ofrece la tecnología láser para desarrollar métodos de procesado por láser que incidan positivamente en el sector de la transformación y modificación de materiales. El conocimiento de los avances en tecnología láser, así como de las propiedades químicas y físicas de materiales de interés industrial, han permitido centrar los esfuerzos del grupo en varias líneas de investigación. Estas líneas se basan, a su vez, en la utilización del láser en modo contínuo, para realizar operaciones de calentamiento y fusión, o en modo pulsante, para realizar trabajos de ablación. En régimen continuo, el grupo estudia la utilización de compuestos precursores organometálicos o de coordinación, para realizar pirólisis y síntesis vía combustión. También se estudia el corte de materiales mediante fusión y expulsión del fundido por gas a presión. Finalmente, se utiliza el láser en configuraciones que permiten fundir y solidificar direccionalmente, para estudiar reacciones novedosas en estado líquido a temperaturas extremas, o bien para obtener nuevos recubrimientos basados en materiales con elevado punto de fusión. En régimen pulsante, el grupo estudia la aplicación de diversos procesos de ablación con objeto de, por una parte, producir mecanizado y corte de metales y cerámicas con mínimo daño y máxima flexibilidad. Por otra, producir materiales nanoparticulados, estudiando la interacción láser-precursor (o, en su caso, preforma) y su efecto sobre la morfología, microestructura y propiedades de los productos obtenidos. Finalmente, se estudian procesos de ablación para la descontaminación de superficies de todo tipo, especialmente metálicas e inorgánicas (pétreas, cerámicas), con el objeto de realizar desarrollos de técnicas de alto rendimiento para la conservación de objetos y edificaciones que forman parte del patrimonio histórico-artístico y cultural europeo.

Laser applications in the transformation and modification of materials. The aim of this research group is to use the advantages posed by laser technology to develop laser processing methods which will have a positive influence on the materials transformation and modification discipline. Knowledge on laser technology advances, as well as on the chemical and physical properties of industrial materials, has allowed the group to centre its efforts around several research themes. These themes are based on the use of the laser in cw mode, to perform heating and melting, or in pulsed mode, to carry out ablation work. In cw mode, the group studies the use of organometallic and coordination complexes to study pirolysis and synthesis via combustion. Cutting of materials is also studied via melting and expulsion of the melt under pressure. Finally, the laser is used under cw mode to achieve melting and directional solidification in systems which provide novel reactions in liquid phase at extreme temperatures. Alternatively, this method may be used to obtain new coatings based on high melting point materials. In pulsed mode, the group studies the application of several ablation techniques with two objectives. On the one hand, to achieve machining and cutting of metals and ceramics with a minimal heat affected zone (HAZ) under the most flexible conditions. On the other hand, to produce nanoparticles, studying the laser-precursor (or preform) material interaction and its effect on final morphology, microstructure and properties of the obtained materials. Finally, ablation processes for surface (all types, specially stone and ceramics) decontamination are also studied within the group, in order to apply the technology to the development of high yield laser methodology applicable to the conservation of cultural heritage.

Publicaciones E. Tejada-Rosales, S. Ondoño-Castillo, C. Diez, G. F. de la Fuente, N. Casañ-Pastor. Annealing of electrophoretic YBa2Cu3O7 coatings on polycrystalline substrates by zonal laser fusion. Bol. Soc. Esp. Ceram. V 2002. 41, 185-189. T. Seeger, G. F. de la Fuente, W. K. Maser, A. M. Benito, M. A. Callejas, M. T. Martínez. Evolution of multiwall carbon-nanotube/SiO2 composites via laser treatment. Nanotechnology 2003, 14, 184-187. Proyectos Aplicación de métodos numéricos sin malla a la simulación de procesos de recubrimiento por láser (DPI2002-01986). Vanguardia, tradición y nuevos desarrollos tecnológicos en la cerámica tradicional aragonesa (02/COOPERA/ES1368). Miembros del ICMA que participan en esta línea: G. F. de la Fuente, C. I. López, R. Lahoz, V. Lennikov, L. C. Estepa, L. A. Angurel, M. Laguna, M. de Val.

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Fabricación de materiales superconducores de alta temperatura con técnicas de fusión zonal inducida con láser en configuraciones de interés tecnológico. Se han desarrollado materiales masivos de superconductores de la familia Bi2Sr2CaCu2O8 para aplicaciones eléctricas de potencia. En particular se ha trabajado en dos aplicaciones: barras de alimentación híbridas y limitadores de corriente resistivos. En el caso de las barras de alimentación híbridas se han fabricado materiales para desarrollar prototipos para el proyecto DESY. Desde el punto de vista fundamental se ha demostrado la viabilidad de utilizar métodos basados en algoritmos SIMPLEX para optimizar los parámetros de fabricación. Se ha establecido la fuerte correlación que existe entre la segregación radial de fases que se produce durante el proceso de fusión y las propiedades superconductoras de estos materiales. La segunda aplicación se basa en el hecho de que la limitación de grandes intensidades de corriente es una de las aplicaciones de los materiales superconductores y con un mercado definido y lleno de futuro. Pretendemos demostrar que esta tecnología de fusión zonal es válida para obtener materiales de altas prestaciones en configuraciones que les permitan ser utilizados como limitadores de corriente resistivos, bien sea en configuraciones planas (en forma de meandro) o sobre soportes cilíndricos (caminos helicoidales). Estas nuevas disposiciones son adecuadas para obtener grandes longitudes y poder desarrollar limitadores de corriente. De forma simultánea, se está desarrollando una tecnología para depositar capas gruesas de superconductores sobre soportes metálicos o cerámicos por la técnica de la cuchilla enrasadora o por inmersión. Uno de los problemas de los materiales superconductores de alta temperatura para el desarrollo de limitadores de corriente en la generación de puntos calientes, que está asociado intrínsecamente con su carácter cerámico y su baja conductividad térmica. Para poder superar estos problemas se ha desarrollado una técnica de electrodeposición para fabricar recubrimientos metálicos.

Fabrication of high temperature superconductors materials in technological configurations using Laser Floating Zone techniques. We have developed bulk Bi2Sr2CaCu2O8 superconducting materials to be used in large scale electric applications. In particular we have worked in two different applications: hybrid current leads and resistive fault current limiters. Thin rods have been used to develop hybrid current leads prototypes for the DESY project. Basic studies have been performed to demonstrate the possibility of using SIMPLEX algorithms to optimise the fabrication parameters of these materials. It has been found that there is a strong correlation between the radial phase segregation that are induced during the solidification process and the superconducting properties of these materials. The second application is based in the fact that the fault current limitation for high currents is one of the main application of these superconducting materials with a promising future. We will try to demonstrate that these laser melting techniques can be used to obtain materials with high properties and with geometries that can be used for resistive fault current limiters. Two configurations are being developed: planar with a meander configuration and cylindrical with helicoidal configurations. These geometries allow to obtaining materials with high lengths, a fact that is important to obtain safe resistive fault current limiters. At the same time we are applying this technology to obtain superconducting thick films on metallic and ceramic substrates using a tape casting or a dip coating technology. One of the main problems of using high temperature superconductors in fault currents limiters is the hot spot generation, which is associated to the ceramic nature of these materials and their low thermal conductivity. In order to overcome this problem, we have developed an electrodeposition technique that allows to obtain metallic coatings on these ceramic materials.

Publicaciones: E. Natividad, M. Castro, R. Burriel, L. A. Angurel, J. C. Díez, R. Navarro. Correlation of normal and superconducting state properties on textured Bi-2212 ceramic thin rods. Supercond. Sci. Technol. 2002, 15, 1022-1029. E. Natividad, J. C. Díez, L. A. Agurel, J. M. Andrés, A. C. Ferrando, M. C. Mayoral. Radial changes in the microstructure of LFZ-textured Bi-2212 thin rods induced by stoichiometry modifications. Physica C, 2003, 383, 379-387. M. Mora, J. C. Diez, C. I. López-Gascón, E. Martínez, G. F. de la Fuente. Laser textured Bi-2212 in planar geometries. IEEE T. Appl. Supercon. 2003, 13, 3188-3291. Proyectos: Fabricación de materiales superconductores para aplicaciones eléctricas de potencia y análisis de los procesos de degradación en servicio. (MAT2002-04121-C03-02). European network for power application of superconductivity SCENET 2. (EU GCT-201-43047). Miembros del ICMA que participan en esta línea: R. Navarro, G. F. de la Fuente, L. A. Angurel, J. C. Díez, F. Lera, E. Martínez, M. Mora, A. Sotelo, E. Natividad, F. Gimeno

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Fabricación y caracterización de hilos y cintas de MgB2. El descubrimiento de superconductividad a temperaturas por debajo de 40 K en MgB2 a principios del año 2001, abrió un campo nuevo de materiales superconductores con temperaturas críticas situadas entre los superconductores clásicos y los superconductores de alta temperatura (SAT) para su uso en aplicaciones a 20-25 K, fácilmente alcanzables con criogeneradores. La novedad del material, el bajo coste de los elementos que lo forman, su baja anisotropía y las prestaciones alcanzadas hasta el momento, dan un elevado interés científico y técnico a su estudio. El grupo de Superconductividad Aplicada del ICMA está trabajando actualmente en el desarrollo, optimización y análisis de hilos y cintas de materiales compuestos metal/MgB2 con técnicas de polvo en tubo (PET), usando diferentes forros metálicos tales como Cu y Ni. La tecnología PET, ampliamente investigada a escala de laboratorio y completamente desarrollada a escala industrial en estos últimos años para la fabricación de cintas Ag/PbBi-2223, se ha empleado con éxito en la fabricación de hilos compuestos metal/MgB2. En esta técnica, polvo de MgB2 reaccionado o mezclas de Mg+2B sin reaccionar, se empaquetan en el interior de un tubo metálico, que posteriormente se trefila para conseguir hilos o/y se lamina para la fabricación de cintas. Finalmente, es necesario un tratamiento térmico en ausencia de oxígeno para sinterizar o reaccionar el polvo precursor. Obviamente, la elección del tubo metálico es esencial, ya que éste debe conferir estabilidad mecánica, térmica y eléctrica al superconductor sin deteriorar sus propiedades. La investigación se centra actualmente en conseguir mejorar las prestaciones de estos materiales fundamentalmente en dos aspectos: aumento del anclaje de flujo que permita ampliar su rango de aplicación a campos más elevados, así como en la mejora de su estabilidad térmica y mecánica.

Fabrication y caracterization of MgB2 wires and tapes. The recent discovery of superconductivity on MgB2 at temperatures below 40 K in 2001, has opened a new field of superconducting materials with critical temperatures comprised between the existing low temperature (LTS) and high temperature superconductors (HTS), for their use in applications at 20-25 K, easily reachable with cryocoolers. The material novelty, the low cost of the rough materials, its low anisotropy and the promising performances already achieved, have aroused considerable interest in its study from a scientific and technological point of view. The Applied Superconductivity Group at the ICMA is currently working on the development, optimisation and analysis of composite metal/MgB2 wires and tapes using the Powder in Tube (PIT) method, using different metallic sheath, such as Cu and Ni. PIT technology, widely searched at laboratory scale and fully developed at industrial scale in recent years for the fabrication of Ag/PbBi-2223 tapes, has been proven to be useful in the conformation of MgB2 composites. In this technique, fully reacted powders of MgB2 or unreacted Mg+2B powders are packed inside metallic tubes, which are subsequently drawn to wires or/and rolled to tapes. Finally, an additional heat treatment in the absence of oxygen is used to sinter or react the precursor powders. It is clear that the choice of the metallic sheath is crucial as it should be able to provide mechanical, thermal and electrical stability to the superconductor without deteriorating their properties. The research is currently focused on the improvement of these materials in two main aspects: to increase the magnetic flux pinning, in order to enlarge the useful field range of this material; and to improve the thermal and mechanical stability.

Publicaciones: E. Martínez, L. A. Angurel, R. Navarro. Study of Ag and Cu/MgB2 powder-in-tube composite wires fabricated by in situ reaction at low temperatures. Supercond. Sci. Technol. 2002, 15, 1043-1047. E. Martínez, L. A. Angurel, R. Navarro, A. Millán, C. Rillo, M. Artigas. Study of MgB2 powders and Cu/MgB2 powder-in- tube composite wires with Zn addition. IEEE T. Appl. Supercon. 2003, 13, 3210-3213. Proyectos: Fabricación y caracterización de cintas compuestas de BSCCO y plata para aplicaciones eléctricas de potencia. (MAT99-1028). Fabricación de materiales superconductores para aplicaciones eléctricas de potencia y análisis de los procesos de degradación en servicio. (MAT2002-04121-C03-02). Miembros del ICMA que participan en esta línea: R. Navarro, E. Martínez, L. A. Angurel, A. Millán.

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Especiación del hierro biológico La investigación se centra en la monitorización por métodos no convencionales, en particular mediante detección magnética, de los cambios producidos en la especiación del hierro en medios biológicos. La presencia del hierro, en forma de pequeños agregados inorgánicos, en algunos tejidos, especialmente en individuos con sobrecarga de hierro y fundamentalmente en sus especies de almacenamiento, ofrece un comportamiento magnético detectable mediante las técnicas modernas de alta sensibilidad. Este comportamiento es correlacionable con su estructura a escala nanoscópica y permite obtener nuevos datos acerca del metabolismo del hierro. El estudio de ejemplos de fármacos antianémicos, con los mismos criterios, permite asimismo conocerlos mejor y complementar los conocimientos existentes en cuanto a su eficacia. El trabajo se realiza sobre modelos con ratas, mediante administración de fármacos y caracterización post mortem de los tejidos correspondientes. La determinación del contenido de hierro en cada individuo se realiza por métodos convencionales y su especiación, objetivo fundamental del proyecto, se acomete a partir de caracterización magnética, tanto estática como dinámica, mediante técnica SQUID y de microscopia electrónica de transmisión. Los resultados obtenidos deben ser de gran utilidad tanto en farmacología como en el conocimiento más profundo de patologías relacionadas con el metabolismo del hierro.

Speciation of biological iron The research is focused on monitoring, by non conventional methods, in particular by magnetic detection, the changes of the iron speciation in biological media. The presence of iron, as very small inorganic clusters in some tissues, especially in individuals with iron overload and primarily in the iron storage organs, give rise to a magnetic behaviour which is detectable by high sensitivity modern techniques. This behaviour is correlatable with its structure at nanoscopic scale and allows the obtention of new data on the iron metabolism. The study of examples of antianaemic drugs, with the same criteria, allows in addition their better understanding, improving the knowledge about their efficiency. The work takes place with rat models, by means administering drugs and by characterising post mortem the corresponding tissues. The determination of the iron content in each individual is carried out by conventional methods and its speciation, central objective of the project, is assessed by magnetic characterisation, either statical and dynamical, by SQUID techniques and transmission electron microscopy. The obtained results should be of much interest either in pharmacology and in the deeper understanding of pathologies related with the iron metabolism.

Publicaciones F. J. Lázaro, A. Larrea, A. R. Abadía, M. S. Romero. Magnetic study of iron sorbitol. J. Magn. Magn. Mater. 2002, 250, 256-259. F. J. Lázaro, A. Larrea, A. R. Abadía. Magnetostructural study of iron dextran. J. Magn. Magn. Mater. 2003, 257, 346-354. Proyectos Métodos de análisis de tipo magnético para la determinación de formas submicrométricas de presencia de hierro en régimen diluido, y su aplicación a la caracterización de tamices moleculares, fármacos y sistemas biológicos (PB1998-1606). Especiación del hierro biológico (DGA, Grupo emergente). Miembros del ICMA que participan en esta línea: F. J. Lázaro, A. Larrea

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Aplicaciones de la aleación de memoria de forma NiTi en Medicina. De entre las diferentes aleaciones de memoria de forma, la aleación equiatómica de níquel-titanio presenta notables características tanto desde le punto de vista de la transformación austenita- martensita como de las propiedades termo-mecánicas que de ella se derivan: memoria de forma de un camino, de dos caminos, superelasticidad y anelasticidad. La combinación de estas propiedades junto a su biocompatibilidad ha permitido su aplicación tanto al campo de la industria como al de la medicina. En el aspecto básico del material, la investigación se centra en los métodos de entrenamiento para obtener memoria de forma de dos caminos con la mayor eficacia, en la influencia sobre las temperaturas de transformación y en el envejecimiento por fatiga térmica. El grupo también investiga en la modelización del material mediante ecuaciones constitutivas que den cuenta de los fenómenos termomecánicos, como primer paso en el diseño de dispositivos. Las aplicaciones en las que se trabaja son stents para colon, ferulajes para articulaciones y anclajes óseos. Los prototipos se han fabricado mediante tecnología de corte por láser, deformaciones en fase martensita y tratamientos térmicos para la fijación de formas. Otra línea más reciente es la modificación superficial del NiTi mediante implantación iónica para mejorar su biocompatibilidad. Se utilizan técnicas de corrosión en continua y espectroscopia de impedancias.

Development of medical devices based on NiTi shape memory alloy. Amongt the shape memory alloy (SMA) binary NiTi alloys present noticeable transformation characterisitics, mechanical properties and biocompatibility behavior. Applications of these alloys have become widespread for different devices for use in industry and medicine. More of these applications are based on the one-way memory effect, superelasticity, and anelasticity. The research trie to depth in the knowledge of the thermal-mechanical behavior, in particular the training methods to achieve two-way shape memory deformation ( TWSME), its dependence on the initial strain, the influence on thermal parameters of the austenite-martensite transition ans its stability. The group also research in the field of modelling the material by means of constitutive equations in order to design NiTi devices using finite elements simulations. By other hand, we used cutting laser beam technology, as method to obtain initial structures and on the thermal-mechanical treatments to develop work configurations. The applications in medicine of the former know-how are stents for colon, splints for finger joint and suture anchors.

Publicaciones R. Lahoz, L. Gracia-Villa, J. A. Puértolas. Training of the two-way shape memory effect by bending in NiTi Alloys. J. Engineering Materials an. 2002, 124, 397-401. Proyectos Diseño y fabricación de stents metálicos con NiTi. (FD97-2069-C02-02). Miembros del ICMA que participan en esta línea: J. A. Puértolas.

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Mejora del polietileno de ultra alto peso molecular (PEUAPM) utilizado en prótesis articulares. El PEUAPM es el material débil del par metal-polímero o cerámica-polímero en las actuales prótesis de cadera y rodilla. El método de disminuir el desgaste y alargar la vida ¨in vivo¨ de la prótesis es la reticulación de las cadenas por irradiación. Sin embargo, se ha observado que la radiación gamma produce a largo plazo una fragilización del material en zonas sub-superficiales que pudiera estar relacionada con los fallos prematuros del material. Este proceso aparece asociado a una degradación oxidativa como consecuencia de los radicales que se producen durante la escisión de las cadenas en presencia de oxígeno. La alternativa actual pasa por una irradiación con electrones, junto a pre o post procesos térmicos La investigación del grupo se centra en el estudio de la microestrucutura mediante TEM para conocer la influencia de los procesos en la distribución lamelar y cristalinidad del material, y como se manifiestan estos cambios en la fractografía de muestras ensayadas a tracción. Se han analizado polietilenos de prótesis irradiadas con gamma y un envejecimiento natural de más cinco años y de polietilenos obtenidos a partir de prótesis retiradas. También se ha evaluado desde un punto de vista microscópico los procesos de envejecimiento acelerado térmicamente para reproducir el envejecimiento natural. Si bien la reticulación mediante electrones mejora el desgaste en cadera, no parece claro este avance en rodilla debido a que la fatiga juega un papel determinante. Por esta razón, se ha estudiado la resistencia a fatiga de polietilenos irradiados a diferentes dosis con y sin el tratamiento térmico posterior.

Improvement of ultra high molecular weigh polyethylene used in total joint replacements. The most widely accepted configuration of total joint replacement is based on metallic or ceramic components articulating against UHMWPE. During the last decades, gamma irrradiaition in air has been the most widespread sterilization for crsoolinking the polymer and in consequence to obtain an improvement in the wear. However, in the long term there are defects due to oxidation caused by remaining free radicals after irradiaition, so new crosslinking patways have been analysed Electron beam irradiation with prior or further thermal treatments is the new sterilization and crosslinking alternative. The research of the group is focused on the in fluence of these processes on the microstructure, such as the lamellar distribution, with the use of TEM, and the fracture surface behaviour after uniaxial tenile tension by SEM. We have compared samples from protheses with shelf storage time longer than five years with sampled from retired protheses after failure, for testing the presence of the oxidation defects. Therefore, we have assesed from a microstrural aspect, if the ASTM protocols for accelerated thermal aging after gamma irradiaition in air, matching the natural aging. Althoug the electron beam irradiaition is followed by significant improvement in UHMWPE wear resistance, the behaviour in the joint knee replacement is less evident, due to the high contribution of other wear modes as the fatigue wear. We have studied the fatigue resistance of UHMWPE after electron beam irradiation at different doses with or without a remelting process as a further thermal treatment.

Publicaciones J. A. Puértolas, A. Larrea, E. Gómez-Barrena. Fracture behaviour of UHMWPE in non-implanted, shelf-aged knee prostheses after gamma irradiation in air. Biomaterials 2002, 22, 2107-2114. Proyectos Mejora del polietileno de interposición en prótesis totales articulares y evaluación de mecanismos de fallo. (MAT2000-1278). Miembros del ICMA que participan en esta línea: J. A. Puértolas.

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Propiedades mecánicas de materiales compuestos polimero-nanotubos de carbono obtenidos mediante diferentes procesos El modulo de Young axial de los nanotubos de carbono se ha estimado en 1 TPa y su resistencia a tracción en 200 GPa. Estas estructuras son aproximadamente 100 veces más resistentes que el acero y seis veces menos densas. Son estables térmicamente hasta 2800ºC en vacío y sus conductividades térmica y eléctrica son varias veces más altas que el cobre. Por lo tanto, los nanotubos de carbono parecen ser materiales ideales como refuerzo de polímeros por sus propiedades físicas, mecánicas, eléctricas y térmicas, superiores a las fibras actuales. Esta nueva generación de materiales tiene numerosas aplicaciones potenciales, tales como músculos artificiales, componentes ultraligeros para aeronáutica y espacio... Sin embargo, aún existen barreras tales como la dispersión, la adhesión nanotubo-matríz, alineamiento y la optimización del sistema nanotubo-polímero. Estamos trabajando en la purificación de estos materiales, eliminando los catalizadores metálicos, nanopartículas de grafito o carbón desordenado así como en la mejora de la dispersión mediante técnicas ultrasónicas. También estamos trabajando en la mejora de la adhesión entre los nanotubos de carbono y la matríz polimérica para generar una correcta tensión de transmisión entre ambos sistemas, mediante técnicas de plasma. Finalmente, los nanotubos de carbono deben estar alineados para optimizar las propiedades de estos sistemas reforzantes, línea en la que tambien estamos trabajando mediante la aplicación de campos magnéticos.

Mechanical properties of carbon nanotube polymer-matrix composite materials obtained by different processes The Young modulus of carbon nanotubes in the axial direction has been estimated in 1 TPa and its tensile strength in 200 GPa. These structures are about one hundred stronger than steel and their density is about six times lower. Carbon nanotubes are thermally stable up to 2800 ºC in vacuum conditions and their thermal and electrical conductivities are several times higher than copper. Therefore, carbon nanotubes seem to be the right material for reinforcing polymeric matrices since they exhibit superior physical, mechanical, electrical and thermal properties than fibres used nowadays. This new generation of nanocomposites would be ideal for a large variety of applications such as artificial muscles, ultra-light space and aeronautic structural components. However, there are still a number of barriers to overcome for these materials to be used as reinforced systems in composite materials. They are related to dispersion, adhesion, alignment and optimisation of the nanocomposite structures formed by the carbon nanotubes and the polymer where they are embedded. We are working in the purification and dispersion of the nanotubes into the matrix by means of ultrasound techniques. Also, the strong adhesion between the carbon nanotubes and the polymeric matrix, is another goal we are achieving by means of plasma procedures. Finally, the carbon nanotubes must be aligned to optimise the properties of these reinforcing systems, we are applying magnetic field techniques to orient the nanotubes in the right directions.

Publicaciones P. Laborde-Lahoz, W. Maser, T. Martínez, A. Benito, T. Seeger, P. Cano, R. Guzman de Villoria, A. Miravete. Mechanical characterization of carbon nanotube composite materials. Mechanics of Advanced Materials and Structures. TNT weekly, TNTW Issue 2003, 12.

Proyectos Low cost compact solar heaters made of plastic materials and composites (COMPACT) (EU CRAFT-1999-72476). Low risk and totally recyclable structural buildings (SAFEFLOOR) (EU EVK5-CT-2000-00552). Miembros del ICMA que participan en esta línea: A. Miravete, R. Guzmán, N. Tolosana

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Modelizacion numérica de nuevos materiales compuestos de matríz orgánica incluyendo preformas textiles trenzadas La utilización de materiales compuestos ha aumentado rápidamente en los últimos tiempos. Muchos sectores han considerado esta opción, como la óptima debido a sus excelentes prestaciones, elevadas rigidez y resistencia, alta absorción de energía especifica, resistencia a la fatiga y a la corrosión. La inclusión de preformas trenzadas en 2D y 3D permite la generación de complejas geometrías con una arquitectura de hilo tridimensional, específicamente trazada para satisfacer exigentes criterios de comportamiento, más elevados que para metales y materiales compuestos laminados. Esta línea de investigación está centrada en el desarrollo de tecnologías eficientes en coste para llevar a cabo componentes de geometría compleja y altas prestaciones. Para ello, es necesario llevar a cabo un proceso de caracterización mecánica completa y un programa de optimización con objeto de realizar una evaluación completa de esta tecnología. Una caracterización mecánica completa a unos niveles meso- y macro-mecánicos constituye un importante criterio a considerar en la evaluación de la tecnología. A partir de ahí, es posible identificar nuevas aplicaciones, determinar cual es el mejor material y la mejor configuración de la preforma. La caracterización se lleva a cabo siguiendo tres diferentes metodologías:

− Un programa de ensayos. − Modelos de EF meso-mecánicos. − Un modelo analítico de material.

Numerical modelling of new composite materials including braided textile preforms The utilization of composite materials has grown rapidly in the last years. Many sectors have considered them the best choice in many cases due to their outstanding performance, combining high stiffness and strength at low density, high-specific energy absorption, excellent fatigue performance and high corrosion resistance. Moreover, advanced composites reinforced with 2D and 3D braided fabrics allows complex textile preforms to be produced with a 3D yarn architecture, specifically designed to satisfy high design-requirements with performances clearly superior to that of conventional metals or composites. This line is focused on the development of cost-effective braiding technologies for complex shaped high-performance composite products, including design, process and simulation analyses. For this, a complete mechanical characterization and optimisation program was essential in order to perform a scope evaluation of the braiding technology. A complete mechanical characterization in meso and macro mechanical levels will finally constitute an important criterion to be considered in the technological evaluation. Through this, is possible to detect new applications, determine the best material and preform configuration. The braided composites characterization has been carried out by means of three different methodologies:

− An experimental testing program. − Meso-mechanic FE models. − An analytic material model.

Publicaciones A. Miravete, M. A. Jiménez . Application of the finite element method to prediction of onset of delamination growth. Appli. Mech. Rev. 2002, 55- 2, 89-106.

D. Revuelta, A. Miravete. Fatigue damage on composite materials. Int. Appli. Mech. 2002, 38, 121-134. Proyectos Development of a cost-effective 3-D braiding manufacturing process for complex shaped high-performance composite products (COBRAID) (EU G1RD-CT00-00380).

Technologies for carbon fibre reinforced modular automotive body structures (TECABS) (EU G3RD-CT-2000-00102). Miembros del ICMA que participan en esta línea: A. Miravete, J. Cuartero, L. Castejón.

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Materiales dendrímeros funcionales Los dendrímeros son, en general, polímeros globulares, altamente ramificados, de forma tridimensional, tamaño y peso molecular bien definidos que se construyen por procedimientos iterativos o por pasos. La modificación estructural de dendrímeros con unidades anisótropas (mesógenas o promesógenas) da lugar a materiales polímeros con propiedades de cristal líquido, en los que la relación estructura-actividad mesógena puede establecerse de un modo excepcionalmente racional. En estos materiales, las diversas unidades submoleculares se ven forzadas a situarse en posiciones determinadas, provocando importantes modificaciones estéricas, con el fin de conseguir las estructuras más estables. De este modo, los dendrímeros muestran una gran variedad de geometrías macromoleculares que proporcionan organizaciones originales en algunos casos y/o propiedades nuevas y de gran interés en otros. Nuestro grupo trabaja en la síntesis y caracterización de dendrímeros cristal líquido, utilizando gran variedad de estructuras tanto en las unidades (pro)mesógenas como en la porción dendrímera. La caracterización de los dendrímeros se realiza por microscopía óptica, DSC, TGA-DTA, GPC y difracción de rayos X. Asimismo, los materiales dendriméricos se procesan y caracterizan, en ocasiones, como películas delgadas. El estudio completo de los materiales preparados nos permite establecer modelos que explican la relación estructura-propiedades de los mismos. Recientemente, nuestro grupo ha comenzado a investigar en una nueva línea dedicada a la preparación de nanopartículas metálicas encapsuladas en matrices dendriméricas, con el fin de estudiar, entre otras, sus propiedades magnéticas.

Functional dendrimer materials Dendrimers are, in general, globular polymers, highly branched, tridimensional-shaped, with web-defined size and molecular weight, which are built by iterative procedures. The structural modification of dendrimers with anisotropic units (mesogenic or promesogenic) gives rise to polymer materials, in which the structure-mesogenic activity relationship can be satisfactorily rationalised. In these covalent materials, the molecules are forced to adopt very constrained and regular structures and consequently, the different molecular parts tend to adopt the most favourable positions in order to obtain the most stable structure. In this way, dendrimers show a wide variety of macromolecular structures that give rise to original organisations in some cases and/or new and interesting properties in other. Our group is involved in the synthesis and characterisation of liquid crystal dendrimers, using a variety of structures both for the (pro)mesogenic units and for the dendrimer moiety itself. The characterisation of the dendrimers is carried out by a number of techniques, such as optical microscopy, DSC, TGA-DTA, GPC and X-ray diffraction. Moreover, in some cases, the dendrimeric materials are processed and characterised as samples consisting in thin films. The study of the materials allows us to establish models to explain their structure-properties relationship. Recently, our group has started a new research line: the preparation of dendrimer-encapsulated metal nanoparticles, in order to study their magnetic properties.

Publicaciones B. Donnio, J. Barberá, R. Giménez, D. Guillon, M. Marcos, J. L. Serrano. Controlled molecular conformation and morphology in poly(amidoamine) (PAMAM) and poly(propyleneimine)(DAB) dendrimers. Macromolecules 2002, 35, 370-381. J. M. Rueff, J. Barberá, B. Donnio, D. Guillon, M. Marcos, J. L. Serrano. Lamellar to columnar mesophase evolution in a series of PAMAM liquid–crystalline co-dendrimers. Macromolecules 2003, 36, 8368-8375. M. Marcos, A. Omenat, J. L. Serrano. Structure-mesomorphism relationship in terminally functionalised liquid crystal dendrimers. C.R. Chim. 2003, 6, 947-957. Proyectos Super molecular liquid crystal dendrimers. UE (RTN-1999-00311). Polímeros funcionales para aplicaciones en óptica lineal y no lineal. CICYT (MAT2002-04118-C02-01). Miembros del ICMA que participan en esta línea: M. Marcos, J. Barberá, A. Omenat , J. L. Serrano, R. Martín, M. McKenna.

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Polímeros funcionales para aplicaciones ópticas y funcionales La capacidad auto-organizativa de los cristales líquidos puede ser aprovechada en polímeros para desarrollar materiales funcionales con propiedades anisótropas. En nuestro laboratorio se está trabajando en diversas líneas de investigación sobre la síntesis, procesado y estudio de polímeros cristal líquido (LCPs) para dos tipos básicos de aplicaciones: ópticas y mecánicas. Así, la incorporación de grupos fotocrómicos (principalmente azobencenos) y el fotocontrol de sus movimientos o isomerización, permite acceder, por ejemplo, a dispositivos de almacenamiento óptico de información, holografía, guiado de luz o para óptica no lineal. En este tipo de materiales es también posible la inducción de estructuras supramoleculares quirales mediante iluminación con luz en películas de polímeros aquirales. Otra línea de trabajo se centra en el procesado y estudio de películas con anisotropía molecular controlada para luminiscencia polarizada a partir de luminóforos cristales líquidos fotorreactivos, o de polímeros que incorporan fotocrómicos cinamato como orientadores del luminóforo. Una última línea de trabajo, en fibras de LCPs de cadena principal procesados en mesofase, con lo que conlleva un reforzamiento de las propiedades mecánicas en la dirección de orientación molecular.

Functional polymers for optical and mechanical applications The self-organizing ability of liquid crystals polymers gives rise to functional materials having anisotropic properties. In our laboratories, we are working on differente topics related with the synthesis, processing and study of liquid crystal polymers (LCPs) for optical or mechanical applications. Thus, the incorporation of photochromic groups (azobenzenes) on LCPs and the photocontrol of their movements or isomerizations allow us to design optical devices for optical or holographic storage, waveguiding or non-linear optics. Furthermore, photoinduced chirality can be also achieved in these achiral materials by illumination with circular polarized light. Other topic concerns the processing of anisotropic polymeric films having polarized luminescence, which are processed from photoreactive liquid crystal luminophores or polymers which incorporate photochormic cinnamate groups for orienting the luminophores. Finally, another research topic is devoted to the processing of main chain LCPs into fibers. Processig is carried out in the mesophase wich leads to an improvement of mechanical properties along the molecular orientation.

Publicaciones L. Oriol, M. Piñol, J. L. Serrano, R. M. Tejedor. Síntesis, characterization and photoreactivity of liquid crystalline cinnamates. J. Photoch. Photobio. A., 2003, 155, 37-45. J. M. Adell, M. P. Alonso, J. Barberá, L. Oriol, M. Piñol, J. L. Serrano. Structural modifications and fibre processing of hydroxy-functionalised mesogenic polyazomethines. Polymer, 2003, 44, 7829-7841. Proyectos Polímeros funcionales para aplicaciones en óptica lineal y óptica no líneal (proyecto coordinado con el Dpto. de Física de la Materia Condensada). (MAT2002-04118-C02-01). Miembros del ICMA que participan en esta línea: L. Oriol, M. Piñol, J. Barberá, J. L. Serrano, R. Tejedor, A. Viñuales, L. Silvino, P. Forcén.

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Organizaciones supramoleculares basadas en cristales líquidos para aplicaciones en electrónica molecular Los cristales líquidos ofrecen un particular control sobre parámetros como orientación, geometría y simetría de la organización supramolecular. Tomando como base esta particularidad, nuestro grupo se ha planteado la utilización de los cristales líquidos, como herramientas para la preparación y control de organizaciones supramoleculares con orden polar, fundamentalmente no-centrosimétricas, que permitan la manifestación de propiedades ópticas no lineales y/o comportamientos ferro-, antiferro-, o piroeléctricos. Para ello, se está trabajando en dos tipos de organizaciones mesomorfas. Por un lado, cristales líquidos que den lugar a mesofases columnares, con una arquitectura helicoidal quiral. Este tipo de arquitecturas moleculares, además de ofrecer orden polar, se prevé permitirán obtener materiales con propiedades de luminiscencia circularmente polarizada. Asimismo, se plantea la utilización de cristales liquidos organizados en columnas helicoidales quirales como moldes para la generación de estructuras con poros helicoidales. El segundo tipo de estructuras en que se está investigando se basa en moléculas en forma de V, los denominados compuestos banana. Estas estructuras, por su particular geometría, permiten obtener empaquetamientos mesomorfos distintos a los descritos clásicamente, entre los cuales, y debido a la restricción de giros moleculares, algunos proporcionan ordenaciones altamente polares y no centrosimétricas incluso en ausencia de quiralidad. Para el control de ambos tipos de estructuras se plantea utilizar un diseño molecular basado no solo en interacciones covalentes sino también en otras interacciones más dinámicas y direccionales como el enlace de hidrógeno.

Supramolecular organizations based on liquid crsytals for molecular electronics applications Liquid crystals offer a particular control on parameters such as orientation, geometry and symmetry of the supramolecular organization. On the basis of this characteristic, our research is aimed at using liquid crystals, as a tool to prepare and control supramolecular organizations with polar order, non-centrosymmetric, that enable the appearance of ferro, antiferro-, or pyroelectric properties. Or group is working on two types of mesomorphic organization. On one hand, mesogenic molecules that self-organize into columnar mesophases with chiral helical architecture. These structures allow envisaging the achievement of materials displaying circularly polarized luminescence. Likewise we are considering employing chiral helical columnar liquid crystals as templates to build up structures with helical porous. A different type of liquid crystalline structures is based on V-shaped molecules. The so-called ”banana” compounds. These structures, due to their bent geometry, allow mesophases that provide strong polar arrangements, some of them in a non-centrosymmetric way, even for achiral structures. In order to control all these types of architecture we are employing a molecule design based not only in covalent interactions but also in weaker interactions such as the dynamic and directional hydrogen-bonding.

Publicaciones J. Barberá, E. Cavero, M. Lehmann, J. L. Serrano, T. Sierra, J. T. Vázquez. Supramolecular helical stacking of metallomesogens derived from enantiopure and racemic polycatenar oxazolines. J. Am. Chem. Soc. 2003, 125, 4527-4533. J. L. Serrano, T. Sierra. Helical supramolecular organizations from metal-organic liquid crystals. Coord. Chem. Rev., 2003, 242, 73-85. C. Artal, M. B. Ros, J. L. Serrano, N. Pereda, J. Etxebarria, C. L. Folcia, J. Ortega. SHG characterization of different polar materials obtained by in situ photopolymerization. Macromolecules, 2001, 34, 4244-4255. C. Ortega, L. Folcia, J. Etxebarria, N. Gimeno, M. B. Ros. Interpretation of unusual textures in the B2 phase of a liquid crystal composed of bent-core molecules. Phys. Rev. E., 2003, 68, 11707. Proyectos: Materiales moleculares cristal líquido para aplicaciones en electrónica molecular. (MAT2003-07806-CO2-01). Miembros del ICMA que participan en esta línea. B. Ros, T. Sierra, J. L. Serrano, R. Giménez, S. Uriel, M. Savirón, N. Gimeno, R. Piñol, L. Puig, E. Cavero, I. Pintre, F. Vera.

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Sistemas push-pull con propiedades ópticas no lineales de segundo orden Los sistemas push-pull de estructura general D-π-A, siendo D una unidad dadora de electrones y A una unidad aceptora de electrones, conectadas a través de un espaciador conjugado (π), son entidades dipolares que muestran propiedades ópticas no lineales de segundo orden, ya que poseen primeras hiperpolarizabilidades moleculares elevadas. Nuestro grupo trabaja en la preparación y estudio de estos sistemas dipolares, utilizando como unidad D derivados de tetratiafulvaleno o fragmentos proaromáticos relacionados, tales como ditiafulvenos. Por su parte, el fragmento aceptor puede ser un grupo aromático, neutro o cargado o, de nuevo, un grupo proaromático. La modificación de la naturaleza de los grupos terminales y la modulación de la longitud y naturaleza del espaciador permiten optimizar la transferencia de carga intramolecular y, por tanto, la respuesta óptica no lineal de segundo orden. Las propiedades ópticas lineales y no lineales de las moléculas sintetizadas se han evaluado tanto teórica como experimentalmente.

Push-pull systems with second order nonlinear optical properties Push-pull systems of general structure D-π-A, where an electron donor unit (D) and an electron acceptor unit (A) are linked through a conjugated spacer (π), are dipolar entities endowed with second-order nonlinear optical properties, thanks to their high first molecular hyperpolarizabilities. Our group is involved in the synthesis and study of such dipolar systems, where D is either a tetrathiafulvalene derivative or a closely related proaromatic moiety, such as dithiafulvene. The acceptor group, in turn, can be a charged or non-charged aromatic group or a proaromatic fragment too. The nature of the end groups, and the length and the nature of the π spacer can be modulated with a view to maximize the intramolecular charge-transfer and, therefore, the second-order nonlinear optical response. The linear and nonlinear optical properties of the synthesized molecules are evaluated both experimentally and theoretically.

Publicaciones R. Andreu, J. Garín, J. Orduna, G. J. Ashwell, M. A. Amiri, R. Hamilton. (E)-4-[2-(bis(octadecylsulfanyl)tetrathiafulvalenyl)ethenyl]-1-methylpyridinium iodide: synthesis and characterisation of its Langmuir-Blodgett films. Thin Solid Films 2002, 408, 236-239. M. Otero, M. A. Herranz, C. Seoane, N. Martín, J. Garín, J. Orduna, R. Alcalá, B. Villacampa. Synthesis and properties of push-pull chromophores for second-order nonlinear optics derived from π-extended tetrathiafulvalenes (TTFs). Tetrahedron 2002, 58, 7463-7475. R. Andreu, J. Garín, J. Orduna, R. Alcalá, B. Villacampa. Novel NLO-phores with proaromatic donor and acceptor groups. Org. Lett. 2003, 5, 3143-3146. Proyectos Síntesis, caracterización y propiedades ópticas no lineales de nuevos cromóforos de tipo merocianina.(P009/2001). Dadores π-electrónicos y sistemas de transferencia de carga intramolecular basados en heterociclos proaromáticos. (BQU2002-00219) Sistemas de transferencia de carga intramolecular con propiedades ópticas no lineales de segundo y tercer orden. (E39). Miembros del ICMA que participan en esta línea: J. Garín, J. Orduna, R. Andreu, L. Carraquer, C. López, M. Á. Cerdán, R. Alcalá, B. Villacampa.

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Dinámica de inestabilidades termomagnéticas en superconductores de tipo II La investigación de inestabilidades termomagnéticas es un tema fundamental tanto para la comprensión de las propiedades básicas de los superconductores tipo II, como para su adecuada caracterización y en el desarrollo de sus potenciales aplicaciones. Desde 1967, las teorías fenomenológicas de acoplamiento de los fenómenos térmicos y magnéticos se han basado en ciertas hipótesis simplificadoras, ampliamente aceptadas, pero el amplio espectro de observaciones experimentales existente todavía carece de una visión completa y unificada. Se pretende avanzar en este conocimiento, simulando la respuesta detallada del material en los procesos de avalancha de flujo magnético provocados por impulsos térmicos. Para obtener predicciones más cercanas a los experimentos, se van a incorporar a la teoría actual una serie de mecanismos físicos: imanación de equilibrio, efectos de tamaño finito, anisotropía en la corriente crítica, inhomogeneidades y fenómenos de corte de flujo magnético.

Magnetothermal instabilities dynamics in type II superconductors The investigation of magnetothermal instabilities has been a main topic in the field of type-II superconductors and their prospective technological applications. Thus, a vast number of scientific publications can be found on this subject for the conventional hard superconductors, the high-Tc superconducting oxides, and already for the recently discovered intermediate temperature superconductors. Phenomenological theories, in which the coupling of electromagnetic and thermal phenomena is realized under various assumptions have been extensively used for decades. However, a full picture description of the rich experimental scenario is still lacking. We attempt to cover as high as possible a number of open questions by an extended phenomenological approach. In particular, we propose to simulate the detailed time-dependent temperature and electric field profiles along the process of a flux jump for superconductors with various types of E(J) equations. The evolutionary distribution of penetrating flux density will be considered, so as to compare with magnetic measurements. To the moment, merely partial aspects of both topics have been covered. In order to get closer to the structure of the available data, we wish to incorporate a number of mechanisms to the theory: critical state and flux creep regimes, sample-size effects, anisotropy and spatial inhomogeneities in the sample parameters or excitation field.

Publicaciones: A. Badía, C. López. Minimal model for the topology of the critical state in hard superconductors. Capítulo del libro "New Developments in Superconductivity Research". New York: Nova Science Publishers, 2003. pp 209-23 A. Badía, C. López. Vector Magnetic Hysteresis of Hard Superconductors. Phys. Rev. B 2002, 65, 104514. A. de la Cruz, A. Badía. Analytical Model for the Levitation Force between a Small Magnet and a Superconducting Cylinder in the Critical State. Physica B 2002, 321, 356. A. Badía, C. López. The Critical State in Type-II Superconductors with Cross-Flow Effects. J. Low Temp. Phys. 2003, 130, 129-153. Proyectos: Fabricación y caracterización de cintas compuestas de BSCCO y plata para aplicaciones eléctricas de potencia (MAT99-1028). Dinámica de inestabilidades termomagnéticas en superconductores de tipo II (proyecto de investigación de la Universidad de Zaragoza, modalidad B). Miembros del ICMA que participan en esta línea: A. Badía

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Propiedades electromagnéticas de sistemas con constante dieléctrica modulada. Óptica atómica. En la linea de propiedades electromagnéticas se aborda el cálculo de las propiedades electromagnéticas de estructuras dieléctricas periódicas, de la pérdida de energía de partículas cargadas cuando pasan cerca de estructuras metálicas corrugadas y, sobre todo, de las propiedades de transmisión óptica (tanto de la cantidad de luz transmitida como de la distribución angular de dicha luz) a través de sistemas metálicos nanoestucturados. En este ultimo caso, estamos extendiendo el estudio, tanto teórico como experimental (en colaboraciones externas) al régimen de microondas. Muy recientemente, hemos empezado una línea de investigación en óptica atómica, donde estamos estudiando si los efectos que hemos descubierto en ondas de luz tienen una contraparte en sistemas atómicos a muy baja temperatura, donde el comportamiento ondulatorio de los átomos es fundamental. Si esto fuera así, tendríamos toda una serie de dispositivos que nos permitirían el guiado, focalización, alta transmisión, etc. de átomos.

Electromagnetic properties of systems with a spatially modulated dielectric constant. Atom Optics. We are working on the theory of electromagnetic properties of periodic dielectric structures, of the energy loss of charged particles passing close to corrugated metallic structures and, especially, on the optical transmission properties (both the total amount of light passing through and its angular distribution) through nanostructured metallic systems. In this last case, we are extending the study (in close collaboration with experimentalists) to the microwave regime. Very recently, we have started to work on atom optics, where we are analising whether the effects that we have found for electromagnetic waves have a counterpart in atomic systems at very low temperature, where the wave-like behaviour of atoms is of paramount importance. If this were the case, we could have access to a series of devices that could allow the guiding, focalization and high transmission of atoms.

Publicaciones F. J. García-Vidal, L. Martín-Moreno. Transmission and focusing of light in 1D periodically nanostructured metals. Phys. Rev. B 2002, 66, 155412. H. J. Lezec, A. Degiron, E. Devaux, R. A. Linke, L. Martín-Moreno, F. J. García-Vidal, T. W. Ebbesen. Beaming light from a subwavelength aperture, Science 2002, 297, 820-822. L. Martín-Moreno, F. J. García-Vidal, H. J. Lezec, A. Degiron, T. W. Ebbesen. Theory of highly directional emission from single sub-wavelength apertures surrounded by surface corrugations. Phys. Rev. Lett. 2003, 90, 167401. Proyectos Cristales fotónicos y materia condensada blanda. Acoplamiento luz-materia y fenómenos colectivos en nanoestructuras semi-conductoras. (MAT 2002-00139). Miembros del ICMA que participan en esta línea: L. Martín.

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Modos intrínsecos localizados en redes de uniones Josephson y redes no lineales. Las redes de uniones Josephson son dispositivos superconductores de estado sólido con numerosas aplicaciones científicas y tecnológicas. En ellas, es posible estudiar experimentalmente los avances recientes de la física no lineal. Consecuencia de estos trabajos son nuevas aplicaciones tecnológicas. Desde su constitución, nuestro grupo ha trabajado en el estudio teórico de circuitos superconductores basados en uniones Josephson, tanto en aspectos dinámicos como de equilibrio. Sin embargo, desde finales de 1997 llevamos a cabo una estrecha colaboración con el grupo experimental del Prof. Terry P. Orlando del Departamento de Ingeniería Eléctrica y Ciencias de la Computación del Instituto Tecnológico de Massachussets (M.I.T.). En el marco de esta colaboración estamos estudiando desde el punto de vista teórico, de simulación y experimental, la existencia y propiedades de los modos intrínsecos localizados (también llamados "discrete breathers") en distintas redes de uniones Josephson. También estamos interesados en explorar las posibles aplicaciones tecnológicas de estos trabajos. En el aspecto puramente teórico, hemos estudiado los fenómenos de movilidad de breathers en redes disipativas no lineales: modelo Frenkel-Kontorova y en el modelo no lineal discreto de Schrödinger (DNLS).

Intrinsic localized modes (or discrete breathers) in Josephson junction arrays and non linear lattices. Josephson-junction based arrays are solid state superconducting devices with many scientific and technological applications. There, it is possible to experimentally study the recent advances of nonlinear physics. As a result of this work, new technological applications can be explored. From its constitution, our group has worked in the theoretical study of the static and dynamics of superconducting circuits made of Josephson junctions. However, from 1997 it carries out a close collaboration with the experimental group of Prof. Terry P. Orlando, in the Department of Electrical Engineering and Computer Sciences at the Massachussets Institute of Technology (M.I.T.). Within the framework of this collaboration we are studying theoretically, with simulations and experimentally the existence and properties of intrinsic localized modes (also called discrete breathers) in different Josephson-junction arrays. We are also exploring the possible technical applications of our results. On the pure theoretical side, we are also studying mobility phenomena of discrete breathers in non-linear dissipative lattices, like the Frenkel-Kontorova model and the discrete non-linear Schrödinger equation (DNLS).

Publicaciones: J. J. Mazo. Discrete breathers in 2d Josephson-junction arrays. Phys. Rev. Lett. 2002, 89, 234101. J. J. Mazo, T. P. Orlando. Discrete breathers in Josephson arrays. Chaos 2003, 13, 733-743. P. J. Martínez, M. Meister, L. M. Floría, F. Falo. Dissipative discrete breathers: Periodic, quasiperiodic, chaotic and mobile. Chaos 2003, 13, 610-623. Proyectos: Localización y transporte en sistemas discretos no lineales: Aplicación a circuitos superconductores y sistemas biológicos. (PB98-1592). Modos no lineales en redes clásicas y cuánticas de uniones Josephson. Programa hispano-norteamericano de cooperación científica y tecnológica 2000. Localisation by nonlinearity and spatial discreteness, and energy transfer, in crystals, biomolecules and Josephson arrays. (HPRN-CT-1999-00163). Teoría y simulación de sistemas complejos. (BFM2002-00113). Miembros del ICMA que participan en esta línea: F. Falo, L. M. Floría, J. Gómez-Gardeñes, J. J. Mazo, P. J. Martínez, M. Meister, D. Zueco.

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Movimiento direccional de defectos y fluxones en redes no lineales. El problema del movimiento direccional de partículas bajo la acción de fuerzas de media nula (fuerzas puramente ac), ha sido profusamente estudiado en los últimos años. Nuestra contribución en este campo es doble. Por una parte, hemos desarrollado un diseño para la rectificación del movimiento de fluxones en redes de uniones Josephson en forma de anillo. Estas redes de escala mesoscópica constituyen un excelente banco de pruebas para el estudio de este efecto tanto en su variante clásica como en la cuántica. El estudio experimental en el límite clásico-cuántico ha sido hecho recientemente en colaboración con el grupo del Prof. T. P.Orlando en el M.I.T. En la actualidad, estamos realizando un notable esfuerzo de desarrollo de la teoría en el límite cuántico, lo que permitirá una mejor comprensión de los experimentos. Por otra parte, hemos propuesto nuevos mecanismos de transporte direccional en sistemas fluctuantes basados no en la difusión térmica, sino en la interacción entre partículas.

Directional motion of defects and fluxons in nonlinear lattices. The problem of the directional motion of particles under unbiased forces (pure ac forces) has been widely studied in last years. Our contribution to this field has a double side. On one side, we have developed a novel design to achieve rectification in the fluxon motion in ring-shaped Josephson junction arrays. These arrays are an excellent bench-work (in the mesoscopic scale) to study the ratchet effect in an extended system, both in the classical and the quantum regimes. The experimental study, in the classical to quantum crossover has been recently performed by the group of Prof. T.P. Orlando in M.I.T. At present, we are developing very fast and powerful theoretical methods to study the quantum limit. This study will help a better understanding of the recently made experiments. On the other side, we have proposed a new mechanism for directional transport in fluctuating systems ("flashing ratchet"). This mechanism is grounded not in thermal diffusion but in inter-particle interaction.

Publicaciones: F. Falo, P. J. Martínez, J. J. Mazo, T. P. Orlando, K. Segall, E. Trías. Fluxon ratchet potentials in superconducting circuits. Appl. Phys. A 2002, 75, 263-269. L. M. Floría, F. Falo, P. J. Martínez, J. J. Mazo. Transport of modulated phases by pumping. Europhys. Lett. 2002, 60, 174-180. J. L. García-Palacios. Solving quantum master equations in phase space by continued-fraction methods. Europhys. Lett. 2004, 65, 735-741. Proyectos: Localización y transporte en sistemas discretos no lineales: Aplicación a circuitos superconductores y sistemas biológicos. (PB98-1592). Modos no lineales en redes clásicas y cuánticas de uniones Josephson. Programa hispano-norteamericano de cooperación científica y tecnológica 2000. Localisation by Nonlinearity and Spatial Discreteness, and Energy Transfer, in Crystals, Biomolecules and Josephson Arrays. (HPRN-CT-1999-00163). Teoría y Simulación de Sistemas Complejos. (BFM2002-00113). Miembros del ICMA que participan en esta línea: S. Cuesta, F. Falo, L. M. Floría, J. L. García-Palacios, J. J. Mazo, P. J. Martínez, D. Zueco.

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2.2.- Proyectos de Investigación

Research Grants

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2.2.1.- Financiación Europea European Funding 1. Advanced ultra-thin ceramic membranes for efficient industrial processes (CERMOX) Código: DR5D-CT-2000-00351 Fuente de financiación: Unión Europea Importe total: 60.000 euros Investigador principal: Víctor Orera Clemente 2. AMORE. Advanced Magnetic Oxides for Responsive Engineering Código: G5RD-CT-2000-00138 Fuente de financiación: Unión Europea Importe total: 177.500 euros Investigador principal: Manuel Ibarra García 3. COBRAID. Devolpment of a Cost-effective 3D-Braiding manufacturing process for complex shaped high-perfomance composite products. Código: G1RD-CT-2000-00380 Fuente de financiación: Unión Europea Importe total: 230.000 euros Investigador principal: Antonio Miravete de Marco 4. COMPOSIT. Thematic network Código: G4RT-CT-2001-05054 Fuente de financiación: Unión Europea Importe total: 55.000 euros Investigador principal: Antonio Miravete de Marco 5. High field infraestructure cooperative network Código: NET-HPRI-CT/99-40013 Fuente de financiación: Unión Europea Importe total: 7.200 euros Investigador principal: Agustín del Moral Gámiz 6. Integral training and research in homogeneous catalisis by organometallic compounds Código: MPMT-CT-2000-00200 Fuente de financiación: Unión Europea Importe total: 240.000 euros Investigador principal: Luis Oro Giral 7. Localisation by nonlinearity and spatial discreteness and energy transfer in crystals, biomolecules and Josephson arrays Código: HPRN-CT-199-00163 Fuente de financiación: Unión Europea Importe total: 160.000 euros Investigador principal: Luis Mario Floría Peralta 8. Low cost compact solar heaters made of plastic materials and composites (COMPACT) Código: Fuente de financiación: Unión Europea Importe total: 245.700 euros Investigador principal: Antonio Miravete de Marco 9. Low risk and totally recyclable structural buildings (SAFEFLOOR) Código: EVK5-CT-2000-00552 Fuente de financiación: Unión Europea Importe total: 141.743 euros Investigador principal: Antonio Miravete de Marco

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10. New mono and heterometallic azolates as new materials and new materials sources Código: INTAS00-00469 Fuente de financiación: INTAS Importe total: Investigador principal: Luis Oro Giral 11. Phonon spectra, thermodynamic stability and phase transitions in perovskite-like crystals Código: RFBR97-10177 Fuente de financiación: INTAS Importe total: 57.000 euros Investigador principal: Ramón Burriel Lahoz 12. Spin, charge and orbital ordering in complex transition metal oxides: an integrated synthesis and measurements approach (SCOOTMO) Código: HPRN-CT-2002-00293 Fuente de financiación: Unión Europea Importe total: 208.755 euros Investigador principal: Clara I. Marquina García 13. SCENET2. European network for power application of superconductivity Código: GCT2001-43047 Fuente de financiación: Unión Europea Importe total: Investigador principal: Rafael Navarro Linares 14. Supermolecular liquid crystal dendrimers Código: HPRN-CT-2000-00016 Fuente de financiación: Unión Europea Importe total: 180.000 euros Investigador principal: José Luis Serrano Ostáriz 15. Surface plasmon photonics Código: NMP4-CT-2003-505699 Fuente de financiación: Unión Europea Importe total: 173.760 euros Investigador principal: Luis Martín Moreno 16. Technologies for carbon fibre reinforced modular automotive body structures (TECABS) Código: G3RD-CT-2000-00102 Fuente de financiación: Unión Europea Importe total: 144.800 euros Investigador principal: Antonio Miravete de Marco

2.2.2.- Financiación Nacional National Funding 1. Acoplamiento luz-materia y fenómenos colectivos en nanoestructuras semiconductoras Código: BFM2002-10883 Fuente de financiación: MCyT Importe total: 11.176 euros Investigador principal: Luis Martín Moreno 2. Anisotropía magnética y magnetoelasticidad en capas finas de metales de transición Código: HI2002-0167

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Fuente de financiación: MCyT Importe total: 10.400 euros Investigador principal: Miguel Ciria Remacha 3. Aplicación de los métodos sin malla a la simulación numérica de procesos de recubrimiento por láser Código: DPI2002-01986 Fuente de financiación: MCyT Importe total: 130.000 euros Investigador principal: Germán de la Fuente Leis; Begoña Calvo Calzada 4. Activaciones de enlaces carbono-halógeno. Aplicaciones en catálisis homogénea Código: 231-57 Fuente de financiación: MCyT Importe total: 6.000 euros Investigador principal: Montserrat Oliván Escó 5. Caracterización y aplicaciones de nuevos materiales nanoestructuras magnéticos Código: MAT2002-04178-C04-03 Fuente de financiación: MCyT Importe total: 159.855 euros Investigador principal: Jesús Chaboy Nalda 6. Catálisis enantioselectiva por compuestos organometálicos Código: BQU2003-01096 Fuente de financiación: MCyT Importe total: 148.310 euros Investigador principal: José Daniel Carmona Gascón 7. Catálisis homogénea por complejos organometálicos de metales de transición Código: BQU2000-1170 Fuente de financiación: MCyT Importe total: 316.373 euros Investigador principal: Luis Oro Giral 8. Complejos con tiolatos polifuncionales. Preparación y estudio de sus aplicaciones Código: BQU2002-04090-C02-01 Fuente de financiación: MCyT Importe total: 189.259 euros Investigador principal: Mariano Laguna Castrillo 9. Complejos de oro y plata: Preparación, estructura y potenciales aplicaciones Código: BQU2001-2409-C02-01 Fuente de financiación: MCyT Importe total: 144.243 euros Investigador principal: Antonio Laguna Castrillo 10. Complejos hidruros de metales del grupo VIII como precursores de reacciones de acoplamiento carbono-carbono Código: PB-1591 Fuente de financiación: MCyT Importe total: 138.233 euros Investigador principal: Miguel Ángel Esteruelas Rodrigo 11. Complejos organometálicos polinucleares de rodio e iridio. Síntesis, estructura y reactividad Código: PB98-1598 Fuente de financiación: MCyT Importe total: 83.961 euros Investigador principal: María Pilar García Clemente

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12. Complejos quirales inmovilizados con ligandos de tipo azabis (oxazolina) como catalizadores de reacciones enantioselectivas Código: HA2001-0096 Fuente de financiación: MCyT Importe total: 9.556 euros Investigador principal: José María Fraile Dolado 13. Compuestos de coordinación con ligandos polifuncionales: Efecto Jahn-Teller. Estudio de la metodología de la cristalografía no rutinaria; informática no rutinaria Código: PB98-1593 Fuente de financiación: MCyT Importe total: 72.121 euros Investigador principal: Lawrence Rocco Falvello 14. Compuestos organometálicos de metales de transición. Aproximaciones sintéticas a especies de interés científico por su novedad estructural o de enlace o por sus propiedades Código: BQU2002-03997-C02-02 Fuente de financiación: MCyT Importe total: 276.050 euros Investigador principal: Juan Forniés Gracia 15. Corte y marcaje de baldosas cerámicas por láser Código: 95-0351-OP Fuente de financiación: MCyT Importe total: 78.132 euros Investigador principal: Germán de la Fuente Leis 16. Dadores pi-electrónicos y sistemas de transferencia de carga intramolecular basados en heterociclos proaromáticos Código: BQU2002-00219 Fuente de financiación: MCyT Importe total: 93.644 euros Investigador principal: Vicente Javier Garín Tercero 17. Dendrímeros carbosilanos funcionalizados con grupos hidrogenosulfuro como soportes para catalizadores en reacciones de hidroformilación de olefinas Código: Fuente de financiación: MCyT Importe total: Investigador principal: Miguel Ángel Casado Lacabra 18. Desarrollo de aplicaciones catalíticas homogéneas promovidas por complejos de metales de transición Código: BQU2003-05412-C02-02 Fuente de financiación: MCyT Importe total: 217.578 euros Investigador principal: Luis Oro Giral 19. Determinación de la geometría de coordinación de iones de metales de transición mediante análisis cuantitativo de los espectros de absorción de rayos X Código: INFN2001 Fuente de financiación: MCyT Importe total: 3.666 euros Investigador principal: Joaquín García Ruíz 20. Dynamics of nonlinear networks: Localization and mobility Código: HB1999-0104 Fuente de financiación: MCyT

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Importe total: 7.754 euros Investigador principal: Luis Mario Floria Peralta 21. Diseño, síntesis y estudio de compuestos de coordinación con ligandos polifuncionales; cristalografía estructural no-rutinaria; informática cristalográfica Código: BQU2002-00554 Fuente de financiación: MCyT Importe total: 126.130 euros Investigador principal: Lawrence Rocco Falvello 22. Estudio de las propiedades magnéticas y de transporte de los compuestos magnetocalóricos TR5(SixGe1-x)4 Código: HP2002-0047 Fuente de financiación: MCyT Importe total: 7.500 euros Investigador principal: Pedro Algarabel Lafuente 23. Estudio de hilos cuánticos InAs/InP mediante espectroscopia EXAFS y DAFS con radiación de sincrotrón Código: HF2002-0078 Fuente de financiación: MCyT Importe total: 10.200 euros Investigador principal: Mª Grazia Proietti Cecconi 24. Estudio de óxidos de valencia mixta y nanoestructuras de semiconductores: Síntesis, caracterización y aplicación de las espectroscopías de rayos X Código: MAT2002-01221 Fuente de financiación: MCyT Importe total: 283.096 euros Investigador principal: Joaquín García Ruíz 25. Estudio de sistemas magnetorresistivos de alto interés en magnetoelectrónica Código: MAT2002-04657 Fuente de financiación: MCyT Importe total: 277.426 euros Investigador principal: José María de Teresa Nogueras 26. Fabricación de materiales funcionales laminares mediante fusión por zonas asistida por láser Código: MAT2000-1495 Fuente de financiación: MCyT Importe total: 188.334 euros Investigador principal: Rosa Isabel Merino Rubio 27. Fabricación de materiales superconductores para aplicaciones eléctricas de potencia y análisis de los procesos de degradación en servicio Código: MAT2002-04121-C03-02 Fuente de financiación: MCyT Importe total: 186.800 euros Investigador principal: Luis Alberto Angurel Lambán 28. Fabricación de memorias no volátiles basadas en uniones túnel magnéticas Código: HF2002-0115 Fuente de financiación: MCyT Importe total: 10.200 euros Investigador principal: José María de Teresa Nogueras 29. Fabricación y caracterización de cintas compuestas de BSCCO y plata para aplicaciones eléctricas de potencia Código: MAT99-1028

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Fuente de financiación: MCyT Importe total: 111.488 euros Investigador principal: Rafael Navarro Linares 30. Heteroestructuras híbridas con aplicaciones en magnetoelectrónica Código: MAT-2000-1290-C03-01 Fuente de financiación: MCyT Importe total: 198.987 euros Investigador principal: José Ignacio Arnaudas Pontaque 31. Imanes macroscópicos y nanoestructurados Código: MAT2002-00166 Fuente de financiación: MCyT Importe total: 306.312 euros Investigador principal: Juan Bartolomé Sanjoaquín 32. Jornadas sobre el presente y futuro de la investigación en manganitas Código: MAT2000-3144-E Fuente de financiación: MCyT Importe total: 4.508 euros Investigador principal: Manuel Ibarra García 33. Localización y transporte en sistemas discretos no lineales: Aplicación a circuitos superconductores y sistemas biológicos Código: PB98-1592 Fuente de financiación: MCyT Importe total: 42.071 euros Investigador principal: Fernando Falo Forniés 34. Magnetismo y magnetoelasticidad en láminas delgadas y en sistemas masivos fuertemente correlacionados Código: MAT2003-00893 Fuente de financiación: MCyT Importe total: 180.300 euros Investigador principal: César de la Fuente del Rey 35. Magnetismo y radiación de sincrotrón (Acuerdo de colaboración CICYT-INFN) Código: INFN2003 Fuente de financiación: MCyT Importe total: 6.900 euros Investigador principal: Jesús Chaboy Nalda 36. Materiales conductores iónicos para dispositivos electroquímicos de producción y almacenamiento de energía Código: MAT2001-3713-C04-02 Fuente de financiación: MCyT Importe total: 71.881 euros Investigador principal: María Luisa Sanjuán Álvarez 37. Materiales magnéticos avanzados: Síntesis, caracterización y aplicaciones Código: MAT99-0667-C04-04 Fuente de financiación: MCyT Importe total: 41.903 euros Investigador principal: Jesús Chaboy Nalda 38. Materiales magnéticos moleculares: Materiales magnéticos multifuncionales y moléculas biestables para la electrónica molecular Código: MAT2001-3507-C02-02 Fuente de financiación: MCyT Importe total: 169.125 euros

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Investigador principal: Ramón Burriel Lahoz 39. Materiales magnéticos nanoestructurados y masivos con relevantes propiedades para aplicaciones tecnológicas Código: MAT1999-1063-C04-0 Fuente de financiación: MCyT Importe total: 185.016 euros Investigador principal: Manuel Ibarra García 40. Materiales masivos con relevantes propiedades magnetoelectrónicas Código: MAT2000-1756 Fuente de financiación: MCyT Importe total: 191.438 euros Investigador principal: Clara I. Marquina García 41. Materiales moleculares magnéticos. Comportamiento magnético de materiales moleculares y poliméricos Código: MAT2000-1388-C03-03 Fuente de financiación: MCyT Importe total: 70.006 euros Investigador principal: Fernando Palacio Parada 42. Materiales para SOFC’s preparados mediante fusión zonal por láser Código: MAT2003-01182 Fuente de financiación: MCyT Importe total: 187.867 euros Investigador principal: Ángel Larrea Arbáizar 43. Método de análisis de tipo magnético para la determinación de formas submicrométricas de presencia de hierro en régimen diluido y su aplicación a la caracterización de tamices moleculares, fármacos y sistemas biológicos Código: PB98-1606 Fuente de financiación: MCyT Importe total: 49.884 euros Investigador principal: Francisco José Lázaro Osoro 44. Mejora del polietileno de interposición en prótesis totales articulares y evaluación de mecanismos de fallos Código: MAT2000-1278 Fuente de financiación: MCyT Importe total: 104.336 euros Investigador principal: José Antonio Puértolas Ráfales 45. Mejoras en las propiedades superconductoras de barras texturadas por fusión zonal láser debido a la presencia de la fase Bi-2223 Código: HP2001-0008 Fuente de financiación: MCyT Importe total: 2.644 euros Investigador principal: Luis Alberto Angurel Lambán 46. Monocristales de manganitas laminares: Crecimiento y estudio de sus propiedades magnéticas, magnetotransporte y efectos de magnetovolumen Código: HB1999-0056 Fuente de financiación: MCyT Importe total: 7.753 euros Investigador principal: Clara I. Marquina García 47. Motores con imanes permanentes: Optimización dinámica, evaluación de la corrosión de los imanes y nuevos procesos de preparación de materiales para imanes permanentes

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Código: MAT2000-0107-P4-02 Fuente de financiación: MCyT Importe total: 114.914 euros Investigador principal: Javier Rubín Llera 48. Nanoestructuras con propiedades magnéticas controladas por efectos de interfac y de deformación interna Código: Fuente de financiación: MCyT Importe total: Investigador principal: Miguel Ciria Remacha 49. Nanoimanes moleculares Código: MAT2002-00433 Fuente de financiación: MCyT Importe total: 80.648 euros Investigador principal: Javier Campo Ruíz 50. Nuevos aminoácidos en forma enantioméricamente pura. Diseño, síntesis e incorporación en péptidos con interés estructural, industrial y/o biológico Código: PPQ2001-1834 Fuente de financiación: MCyT Importe total: 156.300 euros Investigador principal: Carlos Cativiela Marín 51. Nuevos materiales cristal líquidos para aplicaciones electroópticas y optoelectrónicas Código: MAT2000-1293-C02-01 Fuente de financiación: MCyT Importe total: 132.223 euros Investigador principal: José Luis Serrano Ostáriz 52. Ondas electromagnéticas en medios periódicos Código: Fuente de financiación: MCyT Importe total: 10.602 euros Investigador principal: Luis Martín Moreno 53. Organoderivados de diversos metales de transición: síntesis, caracterización, estudio de sus propiedades y sus posibles aplicaciones Código: PB98-1595-C02-01 Fuente de financiación: MCyT Importe total: 150.253 euros Investigador principal: Juan Forniés Gracia 54. Polímeros funcionales para aplicaciones en óptica lineal y no lineal Código: MAT2002-04118-C02-01 Fuente de financiación: MCyT Importe total: 201.620 euros Investigador principal: Joaquín Barberá Gracia 55. Polímeros funcionales para aplicaciones en óptica lineal y óptica no lineal Código: MAT2002-04118-C02-02 Fuente de financiación: MCyT Importe total: 125.500 euros Investigador principal: Rafael Alcalá Aranda 56. Preparación de catalizadores heterogéneos enantioselectivos basados en arcillas pilareadas Código:

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Fuente de financiación: MAE Importe total: 21.000 euros Investigador principal: José Antonio Mayoral Murillo 57. Preparación y estudio teórico de complejos heteropolinucleares de oro y talio Código: 2003CL0017 Fuente de financiación: MCyT Importe total: Investigador principal: Antonio Laguna Castrillo 58. Procesado por láser de cerámicos estructurales avanzados Código: MAT2000-1533-C03-02 Fuente de financiación: MCyT Importe total: 92.892 euros Investigador principal: José Ignacio Peña Torre 59. Procesamiento por láser de compuestos laminados para aplicaciones estructurales Código: MAT2003-06085-C03-01 Fuente de financiación: MCyT Importe total: 120.500 euros Investigador principal: José Ignacio Peña Torre 60. Propiedades ópticas lineales y no lineales de materiales polímeros con estructura cristal líquido Código: MAT1999-1009-C02-01 Fuente de financiación: MCyT Importe total: 112.389 euros Investigador principal: Rafael Alcalá Aranda; Luis T. Oriol Langa 61. Reacciones estequiométricas y catalíticas de acoplamiento carbono-carbono y carbono-heteroátomo promovidas por complejos de metales de transición Código: BQU2002-00606 Fuente de financiación: MCyT Importe total: 327.400 euros Investigador principal: Miguel Ángel Esteruelas Rodrigo 62. Relación estructura/reactividad en complejos polinucleares de rodio e iridio Código: BQU2002-01729 Fuente de financiación: MCyT Importe total: 82.538 euros Investigador principal: Fernando José Lahoz Díaz 63. Relajación magnética cuántica y diagrama de fases de sistemas de moléculas imán Código: BFM2003-03919-C02-01 Fuente de financiación: MCyT Importe total: 21.825 euros Investigador principal: Julio Fernando Fernández Novoa 64. Síntesis asimétrica de análogos de nucleósidos Código: BQU2001-2428 Fuente de financiación: MCyT Importe total: 158.968 euros Investigador principal: Pedro Merino Filella 65. Síntesis, caracterización y reactividad de complejos de paladio y platino con fosfoiluros y ligandos relacionados. Procesos de activación C-H, C-P y C-C Código: BQU2002-00510 Fuente de financiación: MCyT Importe total: 32.000 euros Investigador principal: Rafael Navarro Martín

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66. Síntesis de hidantoínas racémicas 5-sustituidas precursoras de aminoácidos ópticamente puros por vía enzimática Código: PPQ2000-0322-P4-02 Fuente de financiación: MCyT Importe total: 108.182 euros Investigador principal: José Antonio Mayoral Murillo 67. Síntesis y caracterización de organocomplejos quirales en el metal: Aplicaciones en catálisis enantioselectiva Código: BQU200-0907 Fuente de financiación: MCyT Importe total: 148.953 euros Investigador principal: José Daniel Carmona Gascón 68. Síntesis y estudio estructural de péptidos modelo que incorporan análogos restringidos de finilalanina Código: PPQ2002-00819 Fuente de financiación: MCyT Importe total: 6.000 euros Investigador principal: Ana Isabel Jiménez Sanz 69. Síntesis, estructura y reactividad de complejos como y polimetálicos con posibles propiedades catalíticas o conductoras Código: BQU2002-00074 Fuente de financiación: MCyT Importe total: 95.400 euros Investigador principal: Miguel Ángel Ciriano López 70. Teoría y simulación de sistemas complejos Código: BFM2002-00113 Fuente de financiación: MCyT Importe total: 65.000 euros Investigador principal: Fernando Falo Forniés 2.2.3.- Financiación de las Comunidades Autónomas Regional Funding 1. Aminoácidos y péptidos Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 19.546 euros Investigador principal: Carlos Cativiela Marín 2. Actividad catalítica de compuestos heterometálicos early-late en reacciones de hidroformilación de alquenos Código: P051/2000 Fuente de financiación: DGA Importe total: 44.467 euros Investigador principal: Jesús Julián Pérez Torrente 3. Análogos de nucleósidos. Síntesis de compuestos de alto interés biológico por métodos selectivos. Código: P116/2001 Fuente de financiación: DGA Importe total: 18.030 euros Investigador principal: Tomás Tejero López

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4. Aplicación de la tecnología láser para la mejora del valor añadido de productos basados en yeso y escayola Código: 02/COOPERA/PR1560 Fuente de financiación: DGA Importe total: 30.000 euros Investigador principal: Luis Alberto Angurel Lambán 5. Biomateriales Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 17.628 euros Investigador principal: José Antonio Puértolas Ráfales 6. Caracterización de materiales mediante técnicas de radiación de sincrotrón (CAMRADS) Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 18.179 euros Investigador principal: Joaquín García Ruíz 7. Catálisis heterogéneas en síntesis orgánicas selectivas Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 12.528 euros Investigador principal: José Antonio Mayoral Murillo 8. Compuestos complejos de paladio: Su utilización como catalizadores homogéneos en síntesis orgánica y estudio de su retención en membranas de zeolitas Código: P061/2001 Fuente de financiación: DGA Importe total: 21.035 euros Investigador principal: Rafael Navarro Martín 9. Cristales líquidos y polímeros Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 45.703 euros Investigador principal: José Luis Serrano Ostáriz 10. Desarrollo de nuevos materiales magnéticos de alto interés tecnológico: Nuevas rutas de síntesis y de caracterización microscópica Código: P004/2001 Fuente de financiación: DGA Importe total: 13.523 euros Investigador principal: Jesús Chaboy Nalda 11. Especiación del hierro biológico Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 5.842 euros Investigador principal: Francisco José Lázaro Osoro 12. Estructura y función de proteínas y genes de plantas Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 17.955 euros Investigador principal: Rafael Picorel Castaño

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13. Estudio de compuestos magnéticos con propiedades tecnológicas utilizando altos campos magnéticos pulsados Código: MP09/2003 Fuente de financiación: DGA Importe total: 2.000 euros Investigador principal: Pedro Algarabel Lafuente 14. Estudio de los efectos de la corrosión de imanes permanentes y de las pérdidas ac en cintas e hilos superconductores mediante la aplicación de campos magnéticos alternos de intensidad media (0.1 T) Código: P018/2001 Fuente de financiación: DGA Importe total: 34.589 euros Investigador principal: Agustín Camón Lasheras 15. Estudio de las propiedades antitumorales de complejos de oro Código: P076/2000 Fuente de financiación: DGA Importe total: 24.040 euros Investigador principal: María Concepción Gimeno Floría 16. Estudio, mediante técnicas de resonancia paramagnética electrónica en onda continua y en el dominio temporal, de citocromos de la cadena de transporte electrónico fotosintético Código: P111/2001 Fuente de financiación: DGA Importe total: 24.000 euros Investigador principal: Jesús Ignacio Martínez Martínez 17. Física estadística y no lineal Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 10.855 euros Investigador principal: Luis Mario Floría Peralta 18. IMANA Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 24.000 euros Investigador principal: Juan Bartolomé Sanjoaquín 19. Magnetismo de sólidos Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 22.382 euros Investigador principal: Agustín del Moral Gámiz 20. Materiales moleculares electro fotoactivos Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 5.494 euros Investigador principal: Vicente Javier Garín Tercero 21. Materiales procesados por láser: Preparación y caracterización Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 15.751 euros Investigador principal: Víctor Orera Clemente 22. Memorias magnéticas basadas en el efecto túnel polarizado en espín

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Código: CTPR03/2002 Fuente de financiación: DGA Importe total: 12.000 euros Investigador principal: José María de Teresa Nogueras 23. Nanocomposites magnéticos de matríz polimérica: Preparación, caracterización microscópica, propiedades magnéticas y estudio de aplicaciones Código: CTP2001-I+D Fuente de financiación: DGA Importe total: 12.422 euros Investigador principal: Fernando Palacio Parada 24. Organometálicos y catálisis Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 18.618 euros Investigador principal: Miguel Ángel Esteruelas Rodrigo 25. Propiedades espectroscópicas de iones Pr3+ en cristales de BaFCI, BaFBr y mezclados BaFCIxBr1-x. Código: P069/2000 Fuente de financiación: DGA Importe total: 15.326 euros Investigador principal: Rafael Cases Andreu 26. Química bioorgánica Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 19.546 euros Investigador principal: Pedro Merino Filella 27. Química de la coordinación y catálisis homogéneas Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 55.803 euros Investigador principal: Luis Oro Giral 28. Renovación y ampliación del servicio de medidas magnéticas Código: Fuente de financiación: DGA Importe total: 580.000 euros Investigador principal: Conrado Rillo Millán 29. Síntesis asimétrica de aminoácidos no-proteinogénicos y su incorporación en pequeños péptidos Código: P22/98 Fuente de financiación: DGA Importe total: 90.152 euros Investigador principal: Carlos Cativiela Marín 30. Síntesis, caracterización y propiedades ópticas no lineales de nuevos cromóforos de tipo merocianina Código: P009/2001 Fuente de financiación: DGA Importe total: 18.030 euros Investigador principal: Vicente Javier Garín Tercero 31. Síntesis y propiedades físicas de nanoimanes moleculares obtenidos por nuevos métodos de síntesis Código: CTP2002

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Fuente de financiación: DGA Importe total: 6.000 euros Investigador principal: Javier Campo Ruíz 32. Sistemas de microanálisis por rayos X para los microscopios de barrido y transmisión de SAI Código: Fuente de financiación: DGA Importe total: 165.019 euros Investigador principal: Ángel Larrea Arbáizar 33. Sistemas de suspensión activo para uso en asientos de vehículos y maquinaria Código: P085/2001 Fuente de financiación: DGA Importe total: 18.000 euros Investigador principal: Mario Vicente Maza Frechín 34. Superconductividad aplicada Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 28.294 euros Investigador principal: Rafael Navarro Linares 35. Técnicas de prototipado virtual basadas en voxeles. Técnicas de prototipado rápido basadas en láser. Proyecto PV-VOXEL-PPR LASER Código: P055/2000 Fuente de financiación: DGA Importe total: 36.000 euros Investigador principal: Francisco Serón Arbeola 36. TERMOMAG Código: Grupo de Investigación reconocido por la DGA Fuente de financiación: DGA Importe total: 19.342 euros Investigador principal: Fernando Palacio Parada 37. Vanguardia, tradición y desarrollos tecnológicos en la cerámica tradicional aragonesa Código: 02/COOPERA/ES1368 Fuente de financiación: DGA Importe total: 81.250 euros Investigador principal: Germán de la Fuente Leis 38. Versatilidad del anillo de isoaloxazina como Centro Redox. Implicaciones en procesos de transferencia electrones entre proteínas Código: BQU2001/2520 Fuente de financiación: DGA Importe total: 30.000 euros Investigador principal: Milagros Medina Trullenque 2.2.4.- Financiación de la Industria Industrial Funding 1. Análisis y caracterización estructural de compuestos y materiales químicos (Apoyo tecnológico) Código: Fuente de financiación: DGA Importe total: 60.101 euros

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Investigador principal: Fernando José Lahoz Díaz 2. Análisis y optimización de caja de coche de metro en materiales avanzados Código: Fuente de financiación: Metro Madrid, S.A. Importe total: 191.978 euros Investigador principal: Antonio Miravete de Marco 3. Caracterización de materiales poliméricos Código: Fuente de financiación: Cogullada Castellón, S.L. Importe total: 11.500 euros Investigador principal: José Antonio Mayoral Murillo 4. Caracterización del proceso de polimerización de pastas resistivas mediante calorimetría diferencial de barrido y correlación con medidas eléctricas Código: OTRI 2002/0297 Fuente de financiación: Aragonesa de Componentes Pasivos Importe total: 3.866 euros Investigador principal: Miguel Castro Corella 5. Contrato de colaboración entre el CSIC y la empresa Bruker Española, S.A. para la creación del “Centro de Excelencia ICMA-Bruker” en difracción de rayos X en el ICMA Código: Fuente de financiación: Bruker Española, S.A. Importe total: 180.303 euros Investigador principal: Fernando José Lahoz Díaz 6. Desarrollo de estructuras cristalinas mediante procesado láser Código: Fuente de financiación: Colorobbia España, S.A. Importe total: 63.000 euros Investigador principal: Germán de la Fuente Leis 7. Estudio de reducción de peso en coche de alta velocidad mediante el uso de la tecnología Código: Fuente de financiación: Patentes Talgo, S.A. Importe total: 12.000 euros Investigador principal: Antonio Miravete de Marco 8. Mecanizado láser de fibra de carbono para industria aeronáutica. Estudio del procesado por láser y metodología de corte. Implantación del sistema en planta Código: PROFIT-100100-2003-1 Fuente de financiación: Empresa Airbus Importe total: 45.000 euros Investigador principal: José Ignacio Peña Torre 9. Modificación de superficies de baldosas cerámicas por láser Código: Fuente de financiación: Gres de Nules, S.A. Importe total: 66.110 euros Investigador principal: Germán de la Fuente Leis 10. Optimización y automatización de dos comparadores criogénicos de corriente Código: OTRI 2003/366 Fuente de financiación: TPYCEA Importe total: 180.000 euros Investigador principal: Conrado Rillo Millán

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11. Recubrimientos DLC mediante PECVD para la mejora de las propiedades barrera de botellas de plástico a gases y disolventes Código: OTRI 2002/0094 Fuente de financiación: EDP, S.A. Importe total: 46.309 euros Investigador principal: Miguel Castro Corella 12. Recubrimientos DLC mediante PECVD para la mejora de las propiedades barrera de botellas de plástico a gases y disolventes Código: OTRI 2003/0094 Fuente de financiación: EDP, S.A. Importe total: 67.566 euros Investigador principal: Miguel Castro Corella 13. Síntesis de dihidrofenilglicina Código: OTRI 2002/0356 Fuente de financiación: DSM Deretil Importe total: 12.000 euros Investigador principal: Carlos Cativiela Marín 14. Magnetic permeability measurements on stainless steel simples for LHC Código: Fuente de financiación: DMV Stainless Italia, Bohler Importe total: 150.602,40 euros Investigador principal: Conrado Rillo Millán 15. Propiedades magnéticas de aleaciones intersticiales por reacción gas-sólido Código: Fuente de financiación: Fundación Domingo Martínez Importe total: 6.000 euros Investigador principal: Juan Bartolomé Sanjoaquín

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2.3.- Divulgación Científica Scientific Dissemination

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2.3.1.- Actividades Activities

El ICMA ha participado activamente en diferentes actos de divulgación científica organizados tanto por la Universidad de Zaragoza como por el Consejo Superior de Investigaciones Científicas. Entre ellas, podemos destacar: APERTA: LA UNIVERSIDAD EN LA CALLE Zaragoza, 25 a 28 de septiembre de 2003.

El Rectorado y el Consejo Social de la Universidad de Zaragoza - en colaboración con el Gobierno de Aragón, el Ayuntamiento de Zaragoza, Ibercaja y Caja Inmaculada - organizaron unas jornadas de puertas abiertas. Se trataba de una iniciativa con la que la Universidad de Zaragoza quería abrirse y acercarse más a la sociedad, tanto a los colectivos educativos como a las empresas de su entorno y al público en general. Uno de sus objetivos consistía en informar sobre las titulaciones de todos sus centros y títulos propios, así como de todas las actividades, tanto formativas como investigadoras y de servicio a la sociedad en su conjunto.

El ICMA participó en estas jornadas confeccionando tanto dípticos como pósters, que se presentaron en la carpa del Instituto junto con materiales producidos en sus trabajos.

Diversos miembros del ICMA impartieron conferencias a lo largo de los cuatro días: - “La tecnología láser en la restauración del patrimonio artístico y cultural”, por R. Lahoz. - “Pilas de combustible: una posible energía para el futuro”, por M.A. Laguna. - “El estado del cristal líquido: su belleza y sus aplicaciones”, por L. Oriol y T. Sierra.

The ICMA participated in various scientific dissemination activities organized by the University of Zaragoza and the Spanish Council for Scientific Research. Among the highlighs are the following: APERTA: THE UNIVERSITY IN THE STREET Zaragoza, 25th to 28th September, 2003.

The Rectorate and the Social Council of the University of Zaragoza, in collaboration with the Government of Aragón, the City Council of Zaragoza, the savings institutions Ibercaja and Caja Inmaculada, organized this event as as series of open-door activities. The University participated with outreach activities directed at local schools, businesses and the general public. One of the main aims of this participation was to further public awareness of the major study programs available at the university as well as of its varied training, research and community service programs.

The ICMA participated in these activities with its own stand, brochures and posters, together with sample materials from our own laboratories and eye-catching demonstrations.

Members of ICMA presented lectures as part of the four-day program: - “Laser technology in the restoration of cultural heritage”, R. Lahoz. - “Fuel-Cells: a possible energy for the future”, M. A. Laguna - “The liquid crystal state: its beauty and its applications”, L. Oriol and T. Sierra.

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SEMANA DE LA CIENCIA: DESCUBRE EL CSIC EN ARAGÓN Zaragoza, 10 al 14 de noviembre de 2003 Dentro de las actividades de la “Semana de la Ciencia y la Tecnología”, la delegación del CSIC en Aragón organizó una exposición en la que se presentaban los diferentes Centros del CSIC en Aragón. La delegacion, con esta exposición, intentaba acercar a los estudiantes de nuestra comunidad la labor desarrollada en los Institutos de Investigación que el CSIC tiene en Aragón. La exposición incluía: posters, videos de divulgación científico-técnica, demostraciones, conferencias, etc. También se organizaron unas Jornadas de Puertas Abiertas dentro de los Institutos. Una de las actividades programadas consistió en la conferencia impartida por J. L. Serrano y titulada “Cristales líquidos: Organizaciones supramoleculares en nuestras vidas”.

SCIENCE WEEK: DISCOVER THE CSIC IN ARAGÓN Zaragoza, 10th to 14th November, 2003 As part of “Science and Technology Week”, the delegation of the CSIC in Aragón organized an exposition in which the activities of the CSIC centers in our region were presented. The aim of this activity was to introduce students from all over Aragón to the scientific work being carried out by the CSIC Institutes in this region. Posters, demonstrations, lectures, and a popular-science video were all included in the program. In addition, open-door visits to the different Institutes were organized during the course of the week. One of the activities was a lecture given by J. L. Serrano: “Liquid Crystals: Supramolecular organizations in our lives”.

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2.3.2.- Proyectos Grants 1. Acciones de difusión y divulgación de la ciencia y la tecnología. Código: DIF2003-10374-E Fuente de financiación: MCyT Importe total: 7.725 euros Investigador principal: Ramón Burriel Lahoz 2. Celebración de la Semana de la Ciencia. Código: DIF2003-10066-E Fuente de financiación: MCyT Importe total: 36.900 euros Investigador principal: Juan Bartolomé Sanjoaquín 3. “El circo de la ciencia”. Código: DIF2003-10375 Fuente de financiación: MCyT Importe total: 16.000 euros Investigador principal: Jesús Ignacio Martínez Martínez 4. Exposición itinerante “Descubre el CSIC en Aragón”. Código: DIF2003-10345-E Fuente de financiación: MCyT Importe total: 47.000 euros Investigador principal: Juan Bartolomé Sanjoaquín

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3.- Producción Científica Scientific Productivity

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3.1.- Artículos en Revistas Periódicas Journal Articles 2002 Diseño de tres tipologías de automóviles en diferentes sistemas de material. J. Abad, L. Castejón, V. Berrueco, E. Larrodé, A. Miravete. CIT 2002, 2233-2241. The Jahn-Teller vibronic reduction factors in icosahedral GXG systems. M. Aboughantous, P. B. Oliete, C. A. Bates, J. L. Dunn, V. Z. Polinger, R. Huang, S. P. Rough. J. Phys. Condens. Mat. 2002, 14, 4679-4697. Composition and temperature dependence of the magnetocrystalline anisotropy in Ni2+xMn1+yGa1+z (x+y+z=0) Heusler alloys. F. Albertini, L. Pareti, A. Pauluzi, L. Morellón, P. A. Algarabel, M. R. Ibarra, L. Righi. Appl. Phys. Lett. 2002, 81, 4032-4034. Effect of impurities on the successive phase transitions in (Cs1-xRbx)2ZnI4 compounds. I. P. Aleksandrova, J. Bartolomé, L. R. Falvello, J. M. Torres, A. A. Sukhovskii. J. Phys. Condens. Mat. 2002, 14, 13623-13634. Low-Temperature phase transitions in the trigonal modification of Cs3Bi2Br9 and Cs3Sb2I9. I. P. Aleksandrova, R. Burriel, J. Bartolomé, B. Sh. Bagautdinov, J. Blasco, A. A. Sukhovsky, J. M. Torres, A. D. Vasiljev, L. A. Solovjev. Phase Transit. 2002, 75, 607-620. Influence of phenyl side chain on the conformation of cyclopropane analogues of phenylalanine. C. Alemán, A. I. Jiménez, C. Cativiela, J. J. Pérez, J. Casanovas. J. Phys. Chem. B 2002, 106, 11849-11858. Field effect on phase segregation in the electron-doped mixed valence manganites near a structural instability. P. A. Algarabel, J. M. de Teresa, B. García Landa, L. Morellón, M. R. Ibarra, C. Ritter, R. Mahendiran, A. Maignan, M. Hervieu, C. Martín, B. Raveau, A. Kurbakov, V. Trounov. Phys. Rev. B 2002, 65, Art. Nº 104437. Photoinduced electron-transfer processes in C60-tetrathiafulvalene dyads containing a short or long flexible spacer. E. Allard, J. Cousseau, J. Orduna, J. Garín, H. Luo, Y. Araki, O. Ito. Phys. Chem. Chem. Phys. 2002, 4, 5944-5951.

A new family of sulfur-rich ligands based on the DMIT system: Synthesis and metal complexation of 4-4'-covalently bridged bis(2-thioxo-1,3-dithiol-5-thiolato) units. D. W. Allen, R. Berridge, N. Bricklebank, E. Cerrada, M. E. Light, M. B. Hursthouse, M. Laguna, A. Moreno, P. J. Skabara. J. Chem. Soc. Dalton 2002, 2654-2659. A new series of homoleptic, high-spin organochromium derivatives: Synthesis, characterization and study of their magnetic properties. P. J. Alonso, J. Forniés, M. A. García-Monforte, A. Martín, B. Menjón, C. Rillo Chem. Eur. J. 2002, 8, 4056-4065. The first structurally characterised homoleptic σ-organotitanium (III) compound. P. J. Alonso, J. Forniés, M. A. García-Monforte, A. Martín, B. Menjón. Chem. Commun. 2002, 728-729. (E)-4-(2-(bis(octadecylsulfanyl)tetrathiafulva-lenyl)thenyl)-1-methylpyridinium iodide. R. Andreu, J. Garín, J. Orduna, G. J. Ashwell, M. A. Amiri, R. Hamilton. Thin Solid Films 2002, 408, 236-239. The neutral diradical 5,5'-bis(1,3,2,4-dithiadiazolyl) [SNSNC-CNSNS], the first main group radical to exhibit a dramatic increase in paramagnetism on mechanical grinding. G. Antorrena, S. Brownridge, T. S. Cameron, F. Palacio, S. Parsons, J. Passmore, L. K. Thompson, F. Zarlaida. Can. J. Chem. 2002, 80, 1568-1583. A luminescent Pt3Pb cluster with three Pt (II)-Pb(II) bonds. I. Ara, L. R. Falvello, J. Forniés, J. Gómez Cordón, E. Lalinde, R. I. Merino, I. Usón. J. Organomet. Chem. 2002, 663, 284-288. Formation of diphenylphosphanylbutadienyl complexes by insertion of two P-coordinated alkynyllphosphanes into a Pt-C6F5 bond. Detection of intermediate and reaction-products. I. Ara, J. Forniés, A. García, J. Gómez, E. Lalinde, M. T. Moreno. Chem. Eur. J. 2002, 8, 3698-3716.

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Magnetoelastic stresses in epitaxial (110) terfenol-d thin-films. J. I. Arnaudas, C. de la Fuente, M. Ciria, L. Benito, C. Dufour, K. Dumesnil, A. del Moral. J. Magn. Magn. Mater. 2002, 240, 389-391. Metastable phases in the Ti-V system. I: Neutron diffraction study of an assessment of structural properties. G. Aurelio, A. Fernández Guillermet, G. Cuello, J. Campo. Metall. Mater. Trans. A 2002, 33, 1307-1317. Structural properties of metastable phases in Zr-Nb alloys III. The athermal Omega phase. G. Aurelio, A. Fernández Guillermet, G. Cuello, J. Campo. J. Alloy Comp. 2002, 335, 132-138. Aspartame analogues containing 1-amino-2-phenylcyclohexanecarboxylic acids (c6Phe). A. Avenoza, M. París, J. M. Peregrina, M. Alías, M. P. López, J. I. García, C. Cativiela. Tetrahedron 2002, 58, 4899-4905. Asymmetric hetero Diels-Alder as an access to carbacephams. A. Avenoza, J. H. Busto, C. Cativiela, F. Corzana, J. M. Peregrina, M. M. Zurbano. J. Org. Chem. 2002, 67, 598-601. β-Turn modulation by incorporation of c6Ser into Xaa-Pro dipeptide. A. Avenoza, J. H. Busto, C. Cativiela, J. M. Peregrina, F. Rodríguez. Tetrahedron Lett. 2002, 43, 1429-1432. Reactivity of (Z)-4-arylidene-5(4H)-Oxazolones. (4+2)-cycloaddition versus (4+3)-cycloaddition/nucleophilic trapping. A. Avenoza, J. H. Busto, C. Cativiela, J. M. Peregrina. Tetrahedron Lett. 2002, 43, 4167-4170. (S)- and (R)-N-Boc-N,O-isopropylidene-α-methylserinals. Preparation, synthesis and applications. A. Avenoza, C. Cativiela, F. Corazana, J. M. Peregrina, D. Sucunza, M. M. Zurbano. Acros Org. Act. 2002, 9, 9-12. Synthesis, activity and theoretical study of ABT-418 analogs. A. Avenoza, J. H. Busto, C. Cativiela, A. Dordal, J. Frigola, J. M. Peregrina. Tetrahedron 2002, 58, 4505-4511. Synthesis of enantiopure analogs of 3-hydroxyproline and derivatives. A. Avenoza, J. I. Barriobero, J. H. Busto, C. Cativiela, J. M. Peregrina. Tetrahedron: Asymmetry 2002, 13, 625-632.

Synthesis of 7-azabicyclo[2.2.1]heptane derivatives via bridgehead radicals. A. Avenoza, J. H. Busto, C. Cativiela, J. M. Peregrina. Tetrahedron 2002, 58, 1193-1197. Tandem Diels-Alder cycloaddition/rearrange- ment: A method for the synthesis of a 2,5,6-trisubstituted biphenyl. A. Avenoza, J. H. Busto, C. Cativiela, J. M. Peregrina. Afinidad 2002, 59, 431-434. Magnetic flux bifurcation and frequency doubling in rotated superconductors. A. Badía, C. López. J. Appl. Phys. 2002, 92, 6110. Vector magnetic hysteresis of hard superconductors. A. Badía, C. López. Phys. Rev. B 2002, 65, Art. Nº 104514. Highly convergent steroselective synthesis of chiral key intermediates in the synthesis of Palinavir from imines derived from L-glyceraldehyde. R. Badorrey, C. Cativiela, M. D. Díaz de Villegas, J. A. Gálvez. Tetrahedron 2002, 58, 341-354. Stereodivergent addition of allylmetal reagents to imines derived from (R)-2,3-di-0-benzylglyceraldehyde by appropriate selection of metal and double stereodifferentiation. R. Badorrey, C. Cativiela, M. D. Díaz de Villegas, J. A. Gálvez. Eur. J. Org. Chem. 2002, 3763-3767. Tert-Butyl(7R)-7[(4S)-2,2-dimethyl-[1,3]dioxo- lan-4-yl]-1,4-diona-8-azaspirol[4.5]decane-8-carboxylate. R. Badorrey, C. Cativiela, M. D. Díaz de Villegas, J. A. Gálvez. Acta Crystallogr. E 2002, 58, 750-752. Dendrimers with laterally grafted mesogens. J. Barberá, R. Giménez, M. Marcos, J. L. Serrano. Liq. Cryst. 2002, 29, 309-314. Chiral hexacatenar metallomesogens: Supramolecular organization versus steric demand of chiral cores. J. Barberá, M. Lehmann, J. L. Serrano, T. Sierra. J. Mater. Chem. 2002, 12, 1342-1350. Unexpected ring-opening reaction to a new cyanamide-thiolate ligand stabilized as a dinuclear gold complex. M. Bardají, A. Laguna, M. R. Pérez, P. G. Jones. Organometallics 2002, 21, 1877-1881.

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Polarised luminescent films containing fluorene cross-linkers obtained by in situ photo-polymerisation. M. Millaruelo, L. Oriol, M. Piñol, P. L. Sáez, J. L. Serrano. J. Photoch. Photobio. A 2003, 155, 29-36. Field-induced magnetic anisotropy in La0.7Sr0.3CoO3. J. Mira, J. Rivas, M. Vázquez, M. R. Ibarra, R. Caciuffo, M. A. S. Rodríguez. Europhys. Lett. 2003, 62, 433-438. Laser textured Bi-2212 in planar geometries. M. Mora, J. C. Díez, C. López Gascón, E. Martínez, G. de la Fuente. IEEE T. Appl. Supercon. 2003, 13, 3188-3191. Long-range ferromagnetic dipolar ordering of high-spin molecular clusters. A. Morello, F. L. Mettes, F. Luis, J. F. Fernández, J. Krzystek, G. Aromi, G. Christou, L. J. de Jongh. Phys. Rev. Lett 2003, 90, Art. No. 017206. Magnetic-martensitic transition of Tb5Si2Ge2 studied with neutron powder diffraction. L. Morellón, C. Ritter, C. Magén, P. A. Algarabel, M. R. Ibarra. Phys. Rev. B 2003, 68, Art. No. 024417. Order-disorder phase transition in Zn1-x MnxGa2Se4. Long-range order parameter versus x. M. C. Morón, S. Hull Phys. Rev. B 2003, 67, Art. No. 125208. Di-2-pyridylmethylamine-based palladium complexes as new catalysts for Heck, Suzuki, and Sonogashira reactions in organic and aqueous solvents. C. Nájera, J. Gil Moltó, S. Karlstrom, L. R. Falvello. Org. Lett. 2003, 5, 1451-1454. Radial changes in the microstructure of LFZ-textured Bi-2212 thin rods induced by stoichiometry modifications. E. Natividad, J. C. Díez, L. A. Angurel, J. M. Andrés, A. C. Ferrando, M. C. Mayoral. Physica C 2003, 383, 379-387. Unusual 1-alkyne dimerization/hydrogenation sequences catalyzed by [Ir(H)2(NCCH3)3(Pi-Pr3)]BF4, Evidence for homogeneous-like mechanism in imidazolium salts. J. Navarro, M. Sagi, E. Sola, F. J. Lahoz, I. T. Dobrinovitch, A. Katho, F. Jóo, L. A. Oro. Adv. Synth. Catal. 2003, 345, 280-288. Electric, magnetic and optical properties of melt growth ceramic composites. V. M. Orera, J. I. Peña, R. I. Merino, A. Larrea, G. de la Fuente. Adv. Sci. Tech. 2003, 33, 885-896.

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Synthesis, characterization and photoreactivity of liquid crystalline cinnamates. L. Oriol, M. Piñol, J. L. Serrano, R. M. Tejedor. J. Photoch. Photobio. A 2003, 155, 37-45. A very special year for Spanish chemistry. L. A. Oro. Anal. Bioanal. Chem. 2003, 377, 587-587. Early (Ti, Zr)-late (Rh, Ir) heteronuclear complexes with bridging sulphido ligands. L. A. Oro, M. A. Ciriano, J. J. Pérez Torrente, M. A. Casado, M.A. F. Hernández-Gruel. Cr. Chim. 2003, 6, 47-57. L. A. Oro; E. Sola; Navarro JDetermination of the helical pitch in the smectic Cα∗ phase by means of gyrotropy measurements. J. Ortega, C. L. Folcia, J. Etxebarría, M. B. Ros. Liq. Cryst. 2003, 30, 109-115. Ortega J; Folcia CL; EtxebarriaInterpretation of unusual textures in the B2 phase of a liquid cristal composed of bent-core molecules. J. Ortega, C. L. Folcia, J. Etxebarria, N.Gimeno, M. B. Ros. Phys. Rev. E 2003, 68, Art. No. 11707.

Nuclear polarization of Nd in the pseudo cubic perovskite NdAlO3 studied by neutron diffraction below 1 K. E. Palacios, J. Bartolomé, F. Luis, R. Sonntag. Phys. Rev. B 2003, 68, 224425. The phases of [(CH3)4N](ClO4) at low temperature. E. Palacios, R. Burriel, P. Ferloni. Acta Crystallogr. B 2003, 59, 625-633. Formation of unusual iridabenzene and metallanaphthalene containing electron-withdrawing substituents. M. Paneque, C. M. Posadas, M. L. Poveda, N. Rendon, V. Salazar, E. Oñate, K. Mereiter. J. Am. Chem. Soc. 2003, 125, 9898-9899. Folding of peptides characterized by c3Val, a highly constrained analogue of valine. C. Peggion, F. Formaggio, M. Crisma, C. Toniolo, A. I. Jiménez, C. Cativiela, B. Kaptein, Q. B. Broxterman, M. Saviano, E. Benedetti. Biopolymers 2003, 68, 178-191. Ni and Co-ZrO2 composites produced by laser zone melting. J. I. Peña, M. Laguna, R. I. Merino, A. Larrea, V. M. Orera, G. Garcia. Ceramic Engeneering 2003, 24, 181-186. The secret of early nanomaterials is revealed, thanks to transmission electron microscopy. J. Pérez Arantegui, A. Larrea. Trac-Trend. Anal. Chem. 2003, 22, 327-329.

Neutron diffraction analysis of the order in a Cu-Al-Ni shape memory alloy processed by powder metallurgy. J. I. Pérez Landazábal, V. Recarte, J. Campo, R. B. Pérez Sáez, M. L. No, J. San Juan. J. Phys. IV 2003,112, 611-614. A magnetic and Mössbauer spectral study of HoFe11Ti and HoFe11TiH. C. Piquer, F. Grandjean, G. J. Long, O. Isnard. J. Alloy Compd. 2003, 353, 33-41. A high-pressure iron K-edge X-ray absorption spectral study of the spin-state crossover in {Fe[HC(3,5-(CH3)2Pz)3]2}I2 and {Fe[HC(3,5-(CH3)2Pz)3]2}(BF4)2 C. Piquer, F. Grandjean, O. Mathon, S. Pascarelli, D. L. Reger, C. A. Little, G. J. Long. Inorg. Chem. 2003, 42, 982-985. A magnetic and Mössbauer spectral study of TbFe11Ti and TbFe11TiH. C. Piquer, R. P. Hermann, F. Grandjean, O. Isnard, G.J. Long. J. Phys. Condens. Mat. 2003, 15, 7395-7409. Magnetic and Mössbauer spectral study of ErFe11Ti and ErFe11TiH. C. Piquer, R. P. Hermann, F. Grandjean, G. J. Long, O. Isnard. J. Appl. Phys. 2003, 93, 3414-3421. Magnetic and Mössbauer spectral properties of DyFe11Ti and DyFe11TiH. C. Piquer, O. Isnard, F. Grandjean, G. J. Long. J. Magn. Magn. Mater. 2003, 265, 156-166. A Mössbauer spectral study of GdFe11Ti and GdFe11TiD. C. Piquer, O. Isnard, F. Grandjean, G. J. Long. J. Magn. Magn. Mater. 2003, 263, 235-242. Lipopeptaibol metabolites of Tolypocladium geodes: Total synthesis, preferred conformation, and membrane activity. M. Rainaldi, A. Moretto, C. Peggion, F. Formaggio, S. Mammi, E. Peggion, J. A. Gálvez, M. D. Díaz de Villegas, C. Cativiela, C. Toniolo. Chem. Eur. J. 2003, 9, 3567-3576. Reinforced concrete beams strengthened for flexural and shear requirements with CFRP: Experimental and numerical analysis. D. Ranz, A. Miravete, M. Carrera, L. Castejón, E. Bernal, J. Cuartero. Comput. Plast., 2003, 227. In situ study of the β phase decomposition process in a Cu-Al-Ni shape memory alloy processed by powder metallurgy. V. Recarte, J. I. Pérez Landazábal, J. Campo, R. B. Pérez Sáez, M. L. No, J. San Juan. J. Phys. IV 2003, 112, 605-609.

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Diffraction anomalous fine-structure spectroscopy at beamline BM2 at the european synchrotron radiation facility. H. Renevier, S. Grenier, S. Arnaud, J. F. Berar, B. Caillot, J. L. Hodeau, A. Letoublon, M. G. Proietti, B. Ravel. J. Synchrotron Radiat. 2003, 10, 435-444. Glancing angle EXAFS of encapsulated self-assembled InAs/InP quantum wires and InAs/GaAs quantum dots. H. Renevier, M. G. Proietti, S. Grenier, G. Ciatto, L. González, J. M. García, J. M. Gerard, J. García. Mat. Sci. Eng. B-Solid. 2003, 101, 174-180. 1: 30.000 cryogenic current comparator with optimum SQUID readout. G. Rietveld, E. Bartolome, J. Sese, P. de la Court, J. Flokstra, C. Rillo, A. Camón. IEEE T. Instrum. Meas. 2003, 52, 621-625. On the sensitivity of cryogenic current comparators, theory and experiments. C. Rillo, J. Sesé, E. Bartolomé, J. Flokstra, A. Camón, G. Rietveld. Metrologia 2003, 40, 51-56. Photoluminescence and radiationless processes in Mn2+-doped Ca1-xSrxF2 fluorites as a function of pressure and temperature. A structural correlation study. F. Rodríguez, I. Hernández, M. Moreno, R. Alcalá. J. Chem. Phys. 2003, 119, 8686-8694. Protagonists in chemistry: Pierre Braunstein. J. Rose, M. Knorr, L. A. Oro, A. Tiripicchio. Inorg. Chim. Acta 2003, 350, XXVII-XXIX . Trapping of metastable high-spin species and weak cooperativity in a mononuclear Fe(II) spin-crossover system. O. Roubeau, M. de Vos, A. F. Stassen, R. Burriel, J. G. Haasnoot, J. Reedijk. J. Phys. Chem. Solids 2003, 64, 1003-1013. Lamellar to columnar mesophase evolution in a series of PAMAM liquid-crystalline codendrimers. J. M. Rueff, J. Barberá, B. Donnio, D. Guillon, M. Marcos, J. L. Serrano. Macromolecules 2003, 36, 8368-8375. Diastereo- and enantioselective synthesis of 1'-C-branched N,O-nucleosides. M. G. Saita, U. Chiacchio, D. Iannazzo, A. Corsaro, P. Merino, A. Piperno, T. Previtera, A. Rescifina, G. Romeo, R. Romeo. Nucleos. Nucleot. Nucl. 2003, 22, 739-742. Effect of thermal cycling on the strength and superconducting properties of laser floating zone textured Bi-2212 rods. A. Salazar, J. Y. Pastor, J. Llorca, E. Natividad, F. J. Gimeno, L. A. Angurel. Physica C 2003, 384, 443-450.

Effect of heat and film thickness on a photoinduced phase transition in azobenzene liquid crystalline polyesters. C. Sánchez, R. Alcalá, S. Hvilsted, P. S. Ramanujam. J. Appl. Phys. 2003, 93, 4454-4460. Cooperative Jahn-Teller phase transition in LaMnO3 studied by X-ray absorption spectroscopy. M. C. Sánchez, G. Subías, J. García, J. Blasco. Phys. Rev. Lett. 2003, 90, Art. No. 045503. Low-temperature structural and Raman studies on rare-earth gallates. D. Savytskii, L. Vasylechko, A. Senyshyn, A. Matkovskii, C. Bahtz, M. L. Sanjuán, U. Bismayer, M. Berkowski. Phys. Rev. B 2003, 68, Art. No. 024101. Application of natural phosphate modified with sodium nitrate in the synthesis of chalcones, a soft and clean method. S. Sebti, A. Solhy, R. Tahir, S. Abdelatif, S. Boulaajaj, J. A. Mayoral, J. I. García, J. M. Fraile, A. Kossir, H. Oumimoun. J. Catal. 2003, 213, 1-6. Evolution of multiwalled carbon-nanotube/SiO2 composites via laser treatment. T. Seeger, G. de la Fuente, W. K. Maser, A. M. Benito, M. A. Callejas, M. T. Martínez. Nanotechnology 2003, 14, 184-187. Chiral codendrimers derived from poly(propyleneimine) dendrimers (DAB). J. L. Serrano, M. Marcos, R. Martín, M. González, J. Barberá. Chem. Mater. 2003, 15, 3866-3872. Helical supramolecular organizations from metal-organic liquid crystals. J. L. Serrano, T. Sierra. Coordin. Chem. Rev. 2003, 242, 73-85. Simplified calculus for the design of a cryogenic current comparator. J. Sesé, E. Bartolomé, A. Camón, J. Flokstra, G. Rietveld, C. Rillo. IEEE T. Instrum. Meas. 2003, 52, 612-616. Magnetization reversal of individual Fe nanowires in alumites studied by magnetic force microscopy. T. G. Sorop, C. Untiedt, F. Luis, L. J. de Jongh, M. Kroll, M. Rasa. J. Appl. Phys. 2003, 93, 7044-7046. Magnetization reversal of ferromagnetic nanowires studied by magnetic force microscopy. T. G. Sorop, C. Untiedt, F. Luis, M. Kroll, M. Rasa, L. J. de Jongh. Phys. Rev. B 2003, 67, Art. No. 014402.

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Anomalous behavior of the electrical resistivity in the giant magnetocaloric compound Gd5(Si0.1Ge0.9)4. J. B. Sousa, M. E. Braga, F. C. Correia, F. Carpinteiro, L. Morellón, P. A. Algarabel, M. R. Ibarra. Phys. Rev. B 2003, 67, Art. No. 134416. Magnetic scattering in RMn12-xFex alloys. J. Stankiewicz, J. Bartolomé, D. Fruchart. Phys. Rev. B 2003, 67, Art. No. 092409. Stereospecific synthesis of trans-2,3-diaryl substituted 1-aminocyclopropanecarboxylic acid derivatives. G. F. Su, H. T. Mu, D. M. Za, L. M. Zeng, C. Cativiela, R. P. Hammer, K. B. Yu. Synthetic. Commun. 2003, 33, 2873-2884. Rhodium, iridium and gold complexes of the short-bite ligand 1-benzyl-2-imidazolyldiphenylphosphine. C. Tejel, M. A. Ciriano, R. Bravi R, L. A. Oro, C. Graiff, R. Galassi, A. Burini. Inorg. Chim. Acta 2003, 347, 129-136. Protonation reactions of dinuclear pyrazolato iridium(I) complexes. C. Tejel, M. A. Ciriano, Millaruelo M, López JA, F. J. Lahoz, L. A. Oro. Inorg. Chem. 2003, 42, 4750-4758. A hexanuclear iridium chain. C. Tejel, M. A. Ciriano, B. E. Villarroya, J. A. López, F. J. Lahoz, L. A. Oro. Angew. Chem. Int. Edit. 2003, 42, 529-532. Is the atmospheric pressure chemical ionisation and collisionally induced methanol loss from protonated dehydroamino acids a retrosynthetic process?. M. Tubaro, M. A. Fedrigo, C. Cativiela, A. I. Jiménez, P. Traldi. Rapid. Commun. Mass. Spectrom. 2003, 17, 107-113. Influence of quenching treatments on structure and conductivity of the Li3xLa2/3-xTiO3 series. A. Várez, J. Ibarra, A. Rivera, C. León, J. Santamaría, M. A. Laguna, M. L. Sanjuán, J. Sanz Chem. Mater. 2003, 15, 225-232. Influencia del cambio de ángulo de bobinado sobre el comportamiento mecánico de los domos de un depósito a presión en materiales compuestos. G. Vargas, J. Cruz, A. Miravete, A. Chiminelli. Materiales Compuestos 2003, 353-361.

Trends in the design, manufacture and evaluation of wind turbine blades. P. S. Veers, T. D. Aschwill, H. J. Sutherlands, D. L. Laird, D. W. Lobitz, D. A. Griffin, J. F. Mandell, W. D. Musial, K. Jackson, M. Zuteck, A. Miravete, S. W. Tsai, J. L. Richmond. Wind Energy 2003, 6, 245-259. Different kinetics of photoinactivation of photosystem I-mediated electron transport and P700 in isolated thylakoid membranes. M. Velitchkova, I. Yruela, M. Alfonso, P. J. Alonso, R. Picorel. J. Photoch. Photobio. B 2003, 69, 41-48. Mössbauer and magnetic evidence for spin frustration in hetero-trinuclear clusters. M. Vopsaroiu, V. Kuncser, J. Bartolomé, V. M. Meriacre, K. I. Turta, I. Prisecaru, G. Filoti Hyperfine Interact. 2003, 5, 213-216. Spin reorientation and crystal-field interaction in TbFe12-xTix single crystals. J. L. Wang, B. García Landa, C. Marquina, M. R. Ibarra, F. M. Yang, G. H. Wu. Phys. Rev. B 2003, 67, Art. No. 014417. Synthesis, thermal expansion, and magnetic properties of Gd3(Fe,Co,Cr)29 compounds. J. L. Wang, C. Marquina, M. R. Ibarra, W. Q. Wang, F. M. Yang, G. H. Wu, O. Tegus, J. C. P. Klaasse, E. Bruck, F. R. de Boer. J. Appl. Phys. 2003, 93, 6924-6926. Detergent effect on cytochrome b559 electron paramagnetic resonance signals in the photosystem II reaction centre. I. Yruela, I. García Rubio, M. Roncel, J. I. Martínez, M. V. Ramiro, J. M. Ortega, P. J. Alonso, R. Picorel. Photoch. Photobio. Sci. 2003, 2, 437-442.

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3.2.- Libros y Obras Colectivas Books and Contributions to Compiled Works E. Buñuel, A. I. Jiménez, M. D. Díaz de Villegas, C. Cativiela “A chiral oxazolone derived from D-glyceraldehyde as an intermediate in the synthesis of enantiomerically pure cyclic amino acids”. En Targets in Heterocyclic Systems. Chemistry and Properties, vol. V.- Cambridge (Reino Unido): Royal Society of Chemistry, 2002.- Pp. 79-112. J. Campo, J. Luzón, F. Palacio, G. J. McIntyre “Superexchange interactions enhanced through spin delocalization in K2FeCl5.H2O”. En Highlight in the year 2002 Annual Scientific Report of the ILL.- Pp. 18-19. S. Domingo, S. Puértolas, F. Sánchez, L. Gracia Villa, J. A. Puértolas “Aplicación de la superelasticidad del NiTi a los stents: Consideraciones termomecánicas”. En Proc VIII Propiedades Mecánicas De Sólidos, 2002.- Pp. 417-424 F. Luis, F. L. Mettes, L. J. de Jongh “Studies of quantum relaxation and coherence in molecular magnets by means of specific heat”. En Magnetoscience: Molecules to material, vol III.- Weinheim: Wiley-VCH, 2002.- P. 169. R. Lahoz, J. A. Puértolas “Entrenamiento y memoria de forma de doble camino en aleaciones NiTi”. En VIII Prop. Mecánicas De Sólidos, 2002. A. Miravete “New Materials and New Technologies applied to Elevators”. Elevator World (USA), 2002.- ISBN: 1-886536-45-7 A. del Moral, M. J. Azanza, A. C. Calvo, R. N. Pérez Bruzón “Cooperative diamagnetism and Ca2+ liberation of plasma membrane molecules explains the neuron responses to applied static and extremely low frequences magnetic fields”. En Proc 2nd Int Workshop On Biological Effects Of Electromagnetic.- Pp. 298-308. M. L. Sanjuán, A. Ansón, M. T. Martínez “Caracterización por espectroscopía Raman de nanotubos de carbono susceptibles de ser utilizados como electrodos en supercondensadores”. En Proc I Workshop Red Pilas De Combust-CSIC, 2002.- Pp. 289-292 M. L. Sanjuán “Espectroscopía Raman de Materiales Componentes en Pilas de Combustibles de Oxido Sólido”. En Proc I Workshop Red Pilas De Combust-CSIC, 2002.- Pp. 125-129. A. Avenoza, J. H. Busto, C. Cativiela, F. Corzana, J. M. Peregrina, D. Sucunza, M. M. Zurbano “Preparation and synthetic applications of (S)-and (R)-N-BOC-N,O-isopropylidene-α-methylserinals”. En Targets in Heterocyclic Systems. Chemistry and Properties, vol. VI.- Cambridge (Reino Unido): Royal Society of Chemistry, 2003.- Pp. 232-244 M. A. Ciriano, L. A. Oro “Pyridopyridines”. En Comprehensive Coordination Chemistry II, From Biology to Nanotechnology, vol. I.- Nueva York, Elservier Pergamon, (2003).- Pp.55-61. F. J. Fernández “Simulation of quantum tunneling in an open system”. En Modeling of complex systems.- Nueva York, Seventh Granada Lecture, (2003).- Pp. 242-250 M. C. Gimeno, A. Laguna “Silver and gold”. En Comprehensive Coordination Chemistry II, vol. VI.- Nueva York, Elsevier Pergamon, (2003).- Pp.83-92 J. J. Mazo “Discrete breather in 2D Josephson junction arrays”. En Procedings of the 3rd Conference Localisation and Energy Transfer in Nonlinear Systems.- World Scientific, (2003).- Pp. 320-322

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J. J. Mazo, F. Falo, T. P. Orlando “Fluxon ratchet potentials”. En Proceedings of the 3rd Conference Localisation and Energy Transfer in Nonlinear Systems.- World Scientifc, (2003).- Pp 323-324 A. Miravete “New materials and new technologies applied to elevators”. Estados Unidos, Elevator World, (2003) L. A. Oro “Hydrogenation by homogeneous catalysts”. En Encyclopedia of Catalysis, vol. IV.- John Wiley & Sons, (2003).- Pp 55-107

L. A. Oro, E. Sola, J. Navarro “Recent developments on hydride iridium trisopropyphosphine complexes, [IrH2(NCCH3)3(PiPr3}]BF4 as hydrogenation catalyst”. En Perspectives in Organometallic Chemistry.- RSC, (2003).- Pp 297-305.

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3.3.- Tesis Doctorales Ph.D. Theses Título: Cryogenic Current Comparators with Optimum SQUID Autor: Elena Bartolomé Director: H. Rogalla, J. Flokstra, Conrado Rillo Millán Calificación: Sobresaliente “cum laude”. Título: Reactividad de ligandos coordinados: a) nitronas; b) tiolatos polifuncionales Autor: Ana Moreno Ruíz Director: Mariano Laguna Castrillo, Elena Cerrada Lamuela Calificación: Sobresaliente “cum laude”. Título: Catálisis heterogénea en la síntesis de precursores de (R)-2-(4-hidroxifenil)glicina Autor: Beatríz Lázaro Peiró Director: José Antonio Mayoral Murillo, José María Fraile Dolado Calificación: Sobresaliente “cum laude”. Título: Síntesis de nuevos edulcorantes tipo aspartame que incorporan fenilalaninas restringidas Autor: Miriam Alías Niño Director: Carlos Cativiela Marín Calificación: Sobresaliente “cum laude”. Título: Estudio de reacciones de activación y acoplamiento en complejos con la unidad ciclopentadienil-osmio Autor: Miguel Baya García Director: Miguel Ángel Esteruelas Rodrigo Calificación: Sobresaliente “cum laude”. Título: Complejos de oro y plata con ligandos que contienen selenio como átomo dador Autor: Silvia Canales Cañas Director: Antonio Laguna Castrillo Calificación: Sobresaliente “cum laude”. Título: Estudio de citocromos en configuración de bajo espín mediante espectroscopías EPR ESEEM. Autor: Inés García Rubio Director: Pablo Javier Alonso Gascón, Jesús Ignacio Martínez Martínez Calificación: Sobresaliente “cum laude”. Título: Correlación entre parámetros de procesado, microestructura y propiedades físicas en superconductores texturados de Bi2Sr2CaCu2O8+δ. Autor: Eva Natividad Blanco Director: Luis Alberto Angurel Lambán, Miguel Castro Corella Calificación: Sobresaliente “cum laude”. Título: Análisis y modelización del comportamiento a partir de preformas textiles tridimensionales tipo "3D Braiding" Autor: José Manuel Bielsa Gimeno Director: Antonio Miravete de Marco Calificación: Sobresaliente “cum laude”. Título: Formación y reacciones de nuevos complejos hidruro de osmio Autor: María Ángeles Tajada Serrano Director: Miguel Ángel Esteruelas Rodrigo, Montserrat Oliván Escó Calificación: Sobresaliente “cum laude”.

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Título: Síntesis asimétrica de pirrolidinas altamente funcionalizadas. Aplicaciones a la síntesis de aza nucleósidos Autor: Julia Revuelta Crespo Director: Pedro Merino Filella Calificación: Sobresaliente “cum laude”. Título: Estudio de reacciones de activación C-H/. Funcionalización sobre complejos lábiles de iridio Autor: Janeth Navarro Fuenmayor Director: Eduardo Sola Larraya, Luis A. Oro Giral Calificación: Sobresaliente “cum laude”. Título: Nuevos complejos mono- y dinucleares de iridio: Actividad catalítica y reacciones de activación Autor: Francisco Torres Blasco Director: Eduardo Sola Larraya, Ana Isabel Elduque Palomo Calificación: Sobresaliente “cum laude”.

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3.4.- Conferencias Invitadas Invited Lectures 2002 Bistability and transitions in molecular magnetic materials studied by calorimetry R. Burriel 8th European Symposium on Thermal Analysis and Calorimetry, Barcelona (España), agosto 2002 Reactivity and bonding features of rhodium imido complexes M. A. Ciriano, C. Tejel, L. A. Oro 35th International Conference on Coordination Chemistry, Heildelberg (Alemania), julio 2002.

Disconmensuration theory and ratchet transport of modulated phases L. M. Floría, F. Falo, P. J. Martínez, J. J. Mazo Localization and energy transfer in nonlinear systems, San Lorenzo de El Escorial (España), junio 2002 Synthesis and properties of polynuclear gold-tallium complexes A. Laguna, E. J. Fernández, J. M. López de Luzuriaga, M. Monge, M. E. Olmos, J. Pérez SFC Eurochem, Toulouse (Francia), julio 2002 Efectos cuánticos en nanoimanes F. Luis, F. Mettes, G. Aromi, J. Bartolomé, L. J. de Jongh Reunión del grupo especializado de Física del Estado Sólido (GEFES) de la Real Sociedad Española de Física, Calella (España), 2002 Strategies for the immobilization of chiral catalysts containing bis(oxazoline) ligands J. A. Mayoral IV Conference on Green Chemistry. Barcelona (España), 2002 Discrete breathers in 2D Josephson-junction arrays J. J. Mazo Localization and energy transfer in nonlinear systems, San Lorenzo de El Escorial (España), junio 2002 Análogos de nucleósidos con espaciadores heterocíclicos: Diseño y sintesis estereoselectiva. P. Merino VI Semana Científica “Antonio González”. La Química en el Siglo XXI. Universidad de La Laguna (España), octubre 2002.

Nitrone Chemistry: Application to the Synthesis of Highly Functionalized Pyrrolidines. P. Merino 4th Italian-Spanish Symposium on Organic Chemistry. Perugia (Italia), septiembre 2002 Síntesis Estereoselectiva de Nuevos Análogos de Nucleósidos. P. Merino XIX Reunión Bienal de Química Orgánica. Carmona (Sevilla), junio 2002 Magnetic polymer nanocomposites of iron oxides: a simple way to control particle size dand composition A. Millán, F. Palacio, I. Gilbert, A. Falqui, E. Snoeck, V. Serin 3rd EPSRC Nanomagnetism Network Meeting. Edimburgo (Reino Unido), mayo 2002 Sistemas estructurales con materiales de nanotubos de carbono de altas propiedades mecánicas A. Miravete VIII Congreso Nacional de Propiedades Mecáncias de Sólidos. Gandía (España), junio 2002 Recent developments on hydrido iridium triisopropylphosphine complexes L. A. Oro, E. Sola, J. Navarro, V. Jiménez, F. Torres XXth International Conference on Organometallic Chemistry. Corfú (Grecia), 2002 Concluding Remarks F. Palacio VIIIth International Conference on Molecule-based Magnets, ICMM'02, Valencia (España) octubre 2002 Grazing incidence diffraction anomalous fine structure of InAs/InP self-asembled quantum wires M. G. Proietti, H. Renevier, S. Grenier, M. L. González, J. M. García, A. Letoublon NSLS’s Users Workshop, Brookhaven, Upton N.Y. (USA), 2002

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2003 Síntesis, characterisation and liquid cristal properties of PAMAM and DAB Co-dendrimers. J. Barberá, M. Marcos, J. M. Rueff, J. L. Serrano, B. Donnio, D. Guillon DENSOM-Euroconference Dendrimer Soft Self-Assembly Systems, York (Gran Bretaña), septiembre 2003 Supermolecular liquid cristal dendrimer: Liquid cristal organizations versus starburst structures. J. Barberá, M. Marcos, R. Martín, J. M. Rueff, J. L. Serrano VI Workshop Iberoamericano de fluidos complejos y sus aplicaciones. Lisboa (Portugal), septiembre 2003

Cadenas y ciclos metálicos en compuestos de rodio e iridio M. A. Ciriano, C. Tejel, L. A. Oro XXIX Reunión Bienal de la Real Sociedad Española de Química. Madrid (España), julio 2003 Fabricación de capas de eutéctico Al2O3-ZrO2 sobre sustrato de Al2O3 y su transformación microestructural asistida por láser. I. de Francisco, A. J. Sánchez-Herencia, R. Moreno, J. I. Peña, R. I. Merino, A. Larrea, G. F. de la Fuente, V. M. Orera XLIII Congreso de la Sociedad Española de Cerámica y Vidrio. Manises (España), noviembre (2003) Transport of fluxons in Josephson junction arrays F. Falo, J. J. Mazo, P. J. Martínez, K. Segall, T. P. Orlando Workshop, classical and quantum barrier transport. Dresde (Alemania), mayo 2003 Localization and mobility in non-linear shrodinger lattices L. M. Floría, J. Gómez Gardeñes Workshop, intrinsic localised modes and discrete breathers in nonlinear lattices. Erice (Italia), julio 2003 Mechanistic Studies in Enantioselective Catalysis. A Rational Way for Designing Better Catalysts J. I. García 7th Latin American Conference on Physical Organic Chemistry. Florianópolis (Brasil)

Self-organised nano structures D. Guillon, B. Donnio, L. Gehringer, J. L. Serrano, M. Marcos, R. Deschenaux. DENSOM-Euroconference Dendrimer Soft Self-Assembly Systems. York (Gran Bretaña), septiembre 2003

Magnetism fo nanometric 3-d particles in carbon cages: possible relevance for medical applications M. R. Ibarra Spring Meeting European Material Research Society “New Trends in Nanoscience”. Estrasburgo (Francia), junio 2003 The new alchemist: New applications of gold

A. Laguna Not strictly inorganic chemistry. Prullans (Gerona, España), marzo 2003 Complexes F. J. Lahoz 21st European Crystallographic Meeting. Durban (South Africa), agosto 2003

Structural knowledge: a key step in the

progress of Homogeneous catalysis F. J. Lahoz

Workshop on “Opportunities for Synchrotron and Neutron Diffraction in Nanosciences. Bath (Reino Unido), abril 2003 The approach to thermal equilibrium of nanomagnets F. Luis, F. Bartolomé, J. Bartolomé, V. Cross, M. Evangelisti, J. L. García Palacios, L. M. García, V. González, H. Jaffrès, L. J. de Jongh, F. L. Mettes, F. Petroff, J. Stankiewicz. Physics of nanoscale magnets. Kyoto (Japón), 2003 Approach of single-molecule magnets to thermal equilibrium F. Luis, F. L. Mettes, M. Evangelisti, A. Morello, L. J. de Jongh European Materials Research Symposium. Estrasburgo (Francia), 2003 Comportamiento magnético de proteínas de seres vivos F. Luis 1ª Reunión sobre aplicaciones de la nanociencia en medicina. Zaragoza (España), 2003 Liquid cristal Dendrimers based on PAMAN and DAB: Influence of the central core, mesogenic units and terminal chains on the supramolecular organisation. M. Marcos, J. L. Serrano DENSOM-Euroconference Dendrimer Soft Self-Assembly Systems. York (Gran Bretaña), septiembre 2003 Rotobreathers in two-dimensional Josephson arrays J. J. Mazo, D. Zueco Workshop, intrinsic localised modes and discrete breathers in nonlinear lattices. Erice (Italia), julio 2003

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Ceramic composites produced by laser assited directional solidification with eutectic and near eutectic composition. R. I. Merino, J. I. Peña, I. de Francisco, P. B. Oliete, A. Larrea, V. M. Orera 105th Annual Meeting and Exposition of The American Ceramic Society. Nashville (Tenesse, USA), abril (2003). Quantum phenomena in magnetic nanoclusters F. L. Mettes, F. Luis, M. Evangelisti, A. Morello, L. J. de Jongh Quantum Phenomena on the Large Scale. Banff (Canadá), 2003 The naturally nanolayered R5(SixGel1-x)4 materials

L. Morellón, P. A. Algarabel, C. Magén, Z. Arnold, C. Ritter, M. R. Ibarra

5th International Conference on f-elements (ICFE) Functional Properties of Melt Growth Ceramic Eutectics V. M. Orera Directionally Solidified Eutectic Ceramics Workshop. París (Francia), 2003 Functional properties of melt-grown eutectic composites V. M. Orera, J. I. Peña, R. I. Merino, A. Larrea, G. F. de La Fuente Directionally Solidified Eutectic Workshop. París (Francia), mayo 2003 Processing, microstructure and mechanical behavior of directionally solidified eutectic ceramic oxides. V. M. Orera, J. I. Peña, R. I. Merino, A. Larrea, J. LLorca, J. Y. Pastor, P. Poza, J. Martínez, A. Ramírez, M. López, J. Quispe 27th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures. Cocoa Beach (Florida, USA), enero 2003

Magnetic behaviour of S-based free radicals: On the way to high Tc organic magnets F. Palacio Clusters and particles. Okazaki (Japón), febrero 2003 Metal-free high Tc organic magnets F. Palacio DFG Priority Programme on molecular magnetism. Blaubach (Alemania), mayo 2003 Magnetismo y transporte polarizado en espín en la nanoescala J. M. de Teresa III Reunión de la Red Nacional de Nanociencia. Oviedo (España), noviembre 2003

Small-angle neutron scattering in Ga-doped manganites J. M. de Teresa, P. A. Algarabel, M. R. Ibarra, L. Morellón, J. Blasco, C. Ritter, J. I. Espeso, J. C. Gómez-Sal Workshop on “Intrincsic inhomogeneities in strongly correlated electron systemes”, Santander (España), febrero 2003 Structrural, magnetic and transport properties of half-metallic double perovskites J. M. de Teresa, D. Serrate, J. Blasco, L. Morellón, M. R. Ibarra, C. Ritter Workshop on Self Organized Strongly Correlated Electron Systems. Santorini (Grecia), agosto 2003 Role of the interface in oxide-based magnetoresistive systems J. M de Teresa, D. Serrate, P. A. Algarabel, L. Morellón, M. R. Ibarra European Materials Research Symposium. Estrasburgo (Francia), 2003

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4.- Cooperación Científica

Scientific Cooperation

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4.1.- Unidades Asociadas al ICMA ICMA Partner Laboratories Grupo de Síntesis Química de La Rioja (Universidad de la Rioja) Chemical Synthesis Group of La Rioja (University of La Rioja)

● Personal científico permanente / Scientific staff

− Lalinde Peña, Elena Prof. Titular, Responsable de la Unidad Asociada

− Campos García, Pedro José Catedrático − Avenoza Aznar, Alberto Prof. Titular − Berenguer Marín, Jesús Rubén Prof. Titular − Fernández Garbayo, Eduardo J. Prof. Titular − López de Luzuriaga, José María Prof. Titular − Moreno García, Teresa Prof. Titular − Olmos Pérez, Elena Prof. Titular − Peregrina García, Jesús M. Prof. Titular − Zurbano Asensio, Mª Mar Prof. Titular

Científico responsable en el ICMA / Local coordinator at ICMA

− Prof. Juan Forniés Gracia Grupo de Materiales Orgánicos Avanzados (Universidad Jaime I) Advanced Organic Materials Group (University Jaime I)

● Personal científico permanente / Scientific staff

− Luis Lafuente, Santiago Catedrático, Responsable de la Unidad Asociada − Altava Benito, Belén Prof. Titular − Burguete Azcárate, Isabel Prof. Titular − Escuder Gil, Beatriz Prof. Titular − Miravet Celades, Juan F. Prof. Titular

Científico responsable en el ICMA / Local coordinator at ICMA

− Prof. José Antonio Mayoral Murillo

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4.2.- Convenios con Organismos Extranjeros

Collaborative Agreements with Foreign Institutions Laboratorio Europeo Asociado LEA - MANES Associated European Laboratory LEA - MANES

El Laboratorio Europeo Asociado (LEA) para el estudio de materiales por difracción de neutrones y radiación de sincrotrón (MANES) se constituyó por Convenio entre el Instituto de Ciencia de Materiales de Aragón y el Laboratorio de Cristolografía del CNRS de Grenoble el 25 de junio de 1993 con las firmas del Presidente del CSIC, del Rector de la Universidad de Zaragoza, del Director General del CNRS y del Presidente de la Universidad J. Fourier de Grenoble.

Sus temas de investigación se inscriben en dos líneas: El estudio de las propiedades estructurales, termodinámicas, magnéticas y electrónicas de materiales magnéticos y conductores; y el desarrollo de técnicas de difracción, de difusión y de espectroscopia adaptadas a los materiales producidos por los laboratorios cooperantes y su operación en las grandes instalaciones ILL y ESRF.

La formación en investigación e intercambios de personal son también objetivos esenciales de esta cooperación.

Temas de trabajo:

1. Síntesis y propiedades estructurales, termodinámicas, magnéticas y electrónicas de materiales magnéticos. - Síntesis de nuevos compuestos intermetálicos de tierra rara y metal de transición. - Propiedades de materiales magnéticos duros. - Modelización de anomalías de reorientación de spin. - Anomalías en la susceptibilidad magnética ac. - Efecto Hall en monocristales de intermetálicos de tierra rara y metal de transición. 2. Utilización de técnicas de dispersión de neutrones y radiación de sincrotrón. - Magnetismo y radiación de sincrotrón. - Espectroscopía de absorción de rayos-x (XAS, XANES, EXAFS). - Dicroísmo magnético circular en la absorción de rayos-x (XMCD). - Dispersión magnética resonante en la absorción de rayos-x (XRMS). - Dispersión inelástica resonante de rayos-x (RIXS). - Desarrollo de técnicas de difracción. Director: Prof. Ramón Burriel

The Associated European Laboratory (LEA) for the study of materials with neutron diffraction and synchrotron radiation (MANES) was established by an Agreement between the Aragón Materials Science Institute and the CNRS Laboratory of Crystallography in Grenoble on June 25, 1993. The Agreement was signed by the President of the CSIC, the Rector of the University of Zaragoza, the General Director of the CNRS and the President of the University Joseph Fourier of Grenoble.

The research topics of the Laboratory are grouped into two areas -- (1) The study of structural, thermodynamic, magnetic and electronic properties of materials; and (2) the development of diffraction, scattering and spectroscopic techniques adapted to the materials produced in the collaborating laboratories and to operations at the facilities ILL and ESRF.

Reasearch training and scientific exchange are also essential goals of this agreement.

Research topics:

1. Synthesis and structural, thermodynamic, magnetic and electronic properties of magnetic materials. - Synthesis of new intermetallic compounds of rare earths and transition metals. - Properties of hard magnetic materials. - Modelling of spin reorientation materials. - Ac magnetic susceptibility anomalies. - Hall effect in single crystals of rare earth and transition metal intermetallics. 2. Use of neutron scattering techniques and synchrotron radiation. - Magnetism and synchrotron radiation. - X-ray absorption spectroscopy (XAS, XANES, EXAFS). - X-ray magnetic circular dichroism (XMCD). - X-ray resonant magnetic scattering (XRMS). - Resonant inelastic X-ray scattering (RIXS). - Development of diffraction techniques. Director: Prof. Ramón Burriel

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Instrumento CRG: Difractómetro de neutrones D1B CRG: The D1B beamline neutron diffractometer El CSIC mantiene la explotación del CRG (Collaborating Research Group) D1B en el ILL (Instituto von Laue Langevin, Grenoble, Francia) en colaboración con el CNRS. La coordinación científica y administrativa la realiza el ICMA, que ha tenido como científicos responsables contratados en el lugar durante este período a Javier Campo Ruiz y David Martín Marero.

El D1B es un difractómetro de polvo de dos ejes para experimentos que precisan una intensidad de flujo alta. En ángulos pequeños se obtienen altas resoluciones espaciales con anchuras (FWHM) de 0.2º para muestras con diámetro de 8 mm.

El D1B está equipado con un detector de posición compuesto por un sistema de multielectrodos con 400 celdas y un rango de 80º que puede moverse para cubrir un sector de 160º.

Aplicaciones en el D1B:

- Magnetismo: Determinación de estructuras magnéticas, estudio de transiciones de reorientación de spin.

- Estudio de transiciones de fase por termodifractometría.

- Estudios cinéticos con resolución temporal.

- Estudios dinámicos en química de estado sólido.

- Difracción de neutrones in situ.

- Reacciones químicas in situ, intercalación química, reacciones gas-sólido.

- Análisis de texturas.

The CSIC oversees the use of the CRG (Collaborating Research Group) D1B beamline at the ILL (Institute von Laue Langevin, Grenoble, France) in collaboration with the CNRS. ICMA is responsible for scientific and administrative coordination and has had Javier Campo Ruiz and David Martín Marero in place as local coordinators.

D1B is a two-axis powder diffractometer dedicated to diffraction experiments requiring a high neutron flux. At small angles a high spatial resolution can be achieved with a width (FWHM) of 0.2º for samples with a diameter of 8 mm.

D1B is equipped with a position sensitive detector composed of a system of multi-electrodes with 400 cells which span a range of 80º and can be moved to cover a sector of 160º.

Applications of D1B:

- Magnetism: Determination of magnetic structures, study of spin reorientation transitions.

- Investigation of phase transitions by thermodiffractometry.

- Time resolved kinetic studies.

- Dynamical studies in solid state chemistry.

- In situ neutron diffraction.

- In situ chemistry, chemical intercalation, gas-solid reactions.

- Texture analysis.

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4.3.- Estancias de Investigadores del ICMA en Otros Centros (≥ 2 Semanas) Scientific Visits to Other Institutions (≥ 2 Weeks) 2002 Bartolomé Usieto, F. Spring (Japón) / 2 semanas Bartolomé Usieto, F. Lawrence Berkely National Laboratory (USA) / 2 semanas Burriel Lahoz, R. Tokyo Institute of Technology (Japón) / 2 semanas Campo Ruíz, J. Universidad de Sao Paulo. Instituto de Física (Brasil) / 9 semanas Campo Ruíz, J. Institut Laue Langevin, Grenoble (Francia) / 9 meses Cuesta López, S. Ècole Normale Supérieure de Lyon (Francia) CNRS, UMR, 5672 / 6 meses Chaboy Nalda, J. Laboratori Nazionale di Frascati del I.N.F.N., Roma (Italia) / 1 mes Chaboy Nalda, J. Spring, Hyogo (Japón) / 1 mes Falvello, L. R. Texas A&M University (USA) / 1 mes Falvello, L. R. Intense Pulsed Neutron Source, Argonne National Laboratory (USA) / 6 semanas Floría Peralta, L. M. Institute of Mathematics, University of Warwick (Reino Unido) / 1 mes Floría Peralta, L. M. Max-Planck-Institut für Physik Komplexer Systeme, Dresden (Alemania) / 6 semanas Floría Peralta, L. M. FORTH, Heraklion (Grecia) / 3 meses García Palacios, J. L. Universidad de Uppsala (Suecia) / 3 meses García Vinuesa, L. M. Lawrence Berkely National Laboratory (USA) / 2 semanas Lasa Ventura, M. Universidad de Oviedo (España) / 10 semanas

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Luis Vitalla, F. Institute Laue Langevin, Grenoble (Francia) / 3 semanas Marquina García, C. I. University of Warwick (Reino Unido) / 2 semanas Mazo Torres, J. J. Massachusetts Institute of Technology, Cambridge (USA) / 1 mes Palacio Parada, F. Universidad de Sao Paulo (Brasil) / 2 semanas Palacio Parada, F. Univesidad de Cambridge (Gran Bretaña) / 9 semanas Proietti, M. G. Laboratoire de Cristallographie (Grenoble, Francia) / 1 mes Royo Gracia, S. Parque Científico de Barcelona (España) / 2 meses Serrano Ostáriz, J. L. Univesidad de Bayreuth (Alemania) / 1 mes Subías Peruga, G. European Synchrotron Radiation Facility (ESRF), Grenoble (Francia) / 2 semanas Teresa Nogueras, J. M. de Laboratoire de Physique de la Matière Condensée. Toulouse (Francia) / 4 semanas 2003 Badorrey Miguel, R. A. Universidad de Groningen (Holanda) / 5 meses Campo Ruíz, J. Universidad de Sâo Paulo (Brasil) / 3 semanas Campo Ruíz, J. Laboratoire Leon Brillouin, Saclay (Francia) / 4 semanas Campo Ruíz, J. Institut Laue Langevin, Grenoble (Francia) / 4 semanas Chaboy Nalda, J. Laboratori Nazionale di Frascati del I.N.F.N., Roma (Italia) / 1 mes Chaboy Nalda, J. Spring, Hyogo (Japón) / 1 mes Falvello, L. R. Intense Pulsed Neutron Source, Argonne National Laboratory (USA) / 1 mes Palacio Parada, F. Universidad de Tokyo (Japón) / 2 meses Proietti, M. G. Laboratoire DRFMC-SP2M, CEA, Grenoble (Francia) / 2 meses

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Rodríguez Martínez, F. J. University of Technology and Economics, Budapest (Hungría) / 1 mes Serrano Ostáriz, J. L. Universidad de Concepción (Chile) / 2 semanas Subías Peruga, G. European Synchrotron Radiation Facility (ESRF), Grenoble (Francia) / 4 semanas

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