book of abstractsichf.edu.pl/ml2011/files/ml2011_boa.pdf · 2011-09-16 · peter vöhringer,...

Molecules and Light 2011 Autumn Meeting of the Polish Photochemistry Group

Zakopane, 19-23 September 2011

Book of Abstracts

Institute of Physical Chemistry PAS, Warsaw

Jagiellonian University, Cracow Adam Mickiewicz University, Pozna ń

www.ichf.edu.pl/ml2011

Molecules and Light 2011, Zakopane 19-23 September 2011

Official conference web site: www.ichf.edu.pl/ml2011

Important Information Conference venue: Hotel Pod Berłami , Zakopane, ul. Grunwaldzka 9 Tel./fax: +48 18 20 132 21, www.podberlami.com

(all lectures, communications, panel discussion and poster session)

Welcome Dinner: Hotel Carlton , Zakopane, ul. Grunwaldzka 11 (19 Sept. 2011) Tel.: +48 18 20 144 15, www.carlton.pl

Conference Dinner: Karczma Kmicic , Zakopane, ul. Grunwaldzka 25B (21 Sept. 2011) Tel./fax: +48 18 20 663 33, www.karczmakmicic.pl Edition: Jerzy Karpiuk Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw Jagiellonian University, Cracow Adam Mickiewicz University, Poznań

All rights reserved.


Organizing Committee

Conference Chairmen

Jerzy Karpiuk (Institute of Physical Chemistry PAS, Warsaw)

Marek Mac (Faculty of Chemistry, Jagiellonian University, Cracow)

Members

Ewelina Karolak-Solarska (Institute of Physical Chemistry PAS, Warsaw)

Ewa Kuli ś (Faculty of Chemistry, Jagiellonian University, Cracow)

Alina Majka (Institute of Physical Chemistry PAS, Warsaw)

Marek Sikorski (Faculty of Chemistry, Adam Mickiewicz University, Poznań)

Exhibitors COMEF Aparatura Naukowo-Badawcza, Katowice EUROTEK International, Warsaw Merck Sp. z o. o., Warsaw

Table of Contents


Table of Contents

Important Information.............................. ........................... 2

Organizing Committee............................... ......................... 3

Exhibitors ......................................... ................................... 3

Welcome............................................ .................................. 5

Conference Program ................................. ......................... 6

Plenary Lectures ................................... ............................ 11

Invited Lectures ................................... ............................. 19

Panel Discussion ................................... ........................... 27

Oral Communications................................ ....................... 33

Posters ............................................ .................................. 49

Welcome


Welcome Dear colleagues and friends, It is our honour and pleasure to welcome you in Zakopane to attend the Mole-cules and Light 2011 Conference.

The Conference is organised as an autumn meeting of the Polish Photochem-istry Group with the aim to serve as a forum to review current research con-ducted in Poland in the field of photochemistry and photophysics, and to pro-vide opportunity for establishing and strengthening scientific and personal con-tacts between the members of our community. We organise the meeting under the auspices of the European Photochemistry Association, as the Polish Sec-tion of the EPA, as we feel it is an excellent platform to combine a national view of our field with an international perspective.

We are happy that many young researchers, postdocs, PhD and graduate students, have positively responded to our initiative, which gives us the feeling that such a meeting has been expected and needed in our community. We would also like to thank all those who have kindly accepted the invitation to deliver a lecture. The onset of the autumn, with its beautiful colours, but also with the approaching beginning of the new academic year, is especially ap-propriate time not only to review and reconsider recent advances but also to inspire with new concepts and ideas on molecules and light. That’s also, why we hope to continue our initiative in future.

Our meeting is a joint effort of three institutions: the Institute of Physical Chemistry of the Polish Academy of Sciences, the Jagiellonian University and the Adam Mickiewicz University, and we sincerely acknowledge their financial support. We thank also our exhibitors: Comef, Eurotek and Merck Sp. z o.o. for their contributions.

We wish you scientifically challenging, productive and inspiring meeting. We also hope you will enjoy numerous attractions of the capital of Polish Tatra Mountains. Jerzy Karpiuk, Marek Mac, Marek Sikorski

19 September 2011, Zakopane

Conference Program


Conference Program Monday, 19 September, 2011

Monday, 19 September, 2011:

14.00-19.00 Registration

Monday, 19 September 2011 Evening Session: 19.00-20.15

Models and reality Opening Session

19.00-19.15 Welcome addresses 19.15-20.15 Opening lecture

Jacek Waluk, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw

From models to reality: a (very) personal view of photoscience

20.15-23.00 Welcome dinner

Tuesday, 20 September 2011

Tuesday, 20 September 2011 Morning Session: 9.00-13.00

Ultrafast spectroscopy Chairman: Jakob Wirz

9.00-10.00 PL1

Peter Vöhringer , Institute for Physical and Theoretical Chemistry, University of Bonn

Ultrafast dynamics of solvated electrons in H-bonded fluids 10.00-10.45

IL1 Gotard Burdzi ński , Faculty of Physics, Adam Mickiewicz University, Poznań

Ultrafast time-resolved studies of Wolff rearrangement process

10.45-11.15 Coffee break

11.15-12.00 IL2

Thomas Schultz , Max Born Institute, Berlin

Ultrafast spectroscopy of biomolecules and clusters 12.00-12.20

OC1 Jacek Kubicki, Faculty of Physics, Adam Mickiewicz University, Poznań

Direct observation of sulfonyl azide excited state and its decay processes by ultrafast time-resolved IR and UV-Vis spectroscopy

12.20-12.40 OC2

Michał Kijak, Institute of Physical Chemistry, Polish Academy of Science, Warsaw

2-(2-Pyridyl)pyrrole: coupling of photoinduced electron/proton transfer with conformational changes

12.40-13.00 OC3

Marek Sikorski, Faculty of Chemistry, Adam Mickiewicz University, Poznań

The ground- and excited-state double proton transfer in alloxazine and some of its derivatives: Theoretical and experimental approach

Conference Program


Tuesday, 20 September 2011 Afternoon Session: 14.30-17.45

Photocatalysis, organic-semiconductor systems Chairman: Peter Vöhringer

14.30-15.30 PL2

Horst Kisch , Institute of Inorganic Chemistry, University of Erlangen-Nürnberg

Semiconductor visible light photocatalysis – principles and applications 15.30-15.50

OC4 Rafał Sadowski , Faculty of Chemistry, Jagiellonian University, Kraków

Photoactive titanium dioxide coatings on organic polymers


16.20-17.05 IL3

Wojciech Macyk , Faculty of Chemistry, Jagiellonian University, Kraków

Coordination compounds as photosensitizers of titanium dioxide 17.05-17.25

OC5 Marek Oszajca, Faculty of Chemistry, Jagiellonian University, Kraków

Photophysical and electrochemical features of semiconductors modified with polynitriles

17.25-17.45 OC6

Agnieszka Podborska, Faculty of Chemistry, Jagiellonian University, Kraków

New optoelectronic logic devices based on surface-modified TiO2

Tuesday, 20 September 2011 Evening Session: 20.00-21.30

Poster session

Wednesday, 21 September 2011

Wednesday, 21 September 2011 Morning Session: 9.00-13.00

Photochemistry, synthesis, new materials Chairman: Jacek Waluk

9.00-10.00 PL3

Jakob Wirz , Department of Chemistry, University of Basel

Photoremovable protecting groups: How fast are they really? 10.00-10.45

IL4 Daniel Gryko , Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw

Novel π-expanded porphyrins – synthesis and photophysics


11.15-12.00 IL5

Sebastian Ma ćkowski , Institute of Physics, Nicolaus Copernicus University, Toruń

Photomodification of corrole molecules 12.00-12.20

OC7 Mariusz Tasior, Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw

The synthesis and optical properties of novel coumarins 12.20-12.40

OC8 Miłosz Pawlicki, Department of Chemistry, University of Wrocław

Radiationless deactivation of subpyriporphyrins 12.40-13.00

OC9 Maciej Nowak, Institute of Physics, Polish Academy of Sciences, Warsaw

Photon-induced and spontaneous transformations of the structure of cytosine molecule

Wednesday, 21 September 2011, 14.00 – 18.00: Excursion

Wednesday, 21 September 2011 Evening, 19.30 – 23.00

Conference Dinner

Conference Program


Thursday, 22 September 2011

Thursday, 22 September 2011 Morning Session: 9.00-13.15

Electron, proton, energy transfer Chairman: Andrzej Sobolewski

9.00-10.00 PL4

Eric Vauthey , Department of Physical Chemistry, University of Geneva

Excitation energy hopping and photoinduced charge transfer processes in multichromophoric systems

10.00-10.45 IL6

Gonzalo Angulo , Institute of Physical Chemistry, Polish Academy of Sciences, War-saw

Electron transfer and diffusion


11.15-12.15 PL5

Klaas Zachariasse , Max-Planck-Institute for Biophysical Chemistry, Göttingen

Intramolecular charge transfer in the excited state. Dynamics and structure 12.15-12.35

OC10 Ewelina Karolak-Solarska, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw

Electron transfer and photodissociation in a spirocyclic bichromophoric molecule 12.35-12.55

OC11 Anna Szemik-Hojniak, Department of Chemistry, University of Wrocław

Excited state deactivation processes in 3-aminoflavone 12.55-13.15

OC12 Jędrzej Solarski, Institute of Physical Chemistry, Polish Academy of Sciences, War-saw

Investigation of the bi-molecular energy transfer processes in liquid solutions

Thursday, 22 September 2011 Afternoon Session: 15.00-18.30 Panel Discussion

Photoinduced charge transfer and conforma-tional changes Chairman: Jerzy Karpiuk

15.00-16.30 PD

Part 1: Address sent by Zbigniew R. Grabowski

Contributions: Jacek Waluk and Klaas Zachariasse


17.00-18.30 PD

Part 2: Open discussion: short contributions are wel come

Conference Program


Friday, 23 September 2011

Friday, 23 September 2011 Morning Session: 9.00-12.30

Theory and computations Chairman: Eric Vauthey

9.00-10.00 PL6

Andrzej Sobolewski , Institute of Physics, Polish Academy of Sciences, Warsaw

Photophysics of hydrogen bonded systems: from theory to applications 10.00-10.45

IL7 Piotr Skurski , Department of Chemistry, University of Gdańsk

Unusual oxidizing agents


11.15-11.35 OC13

Przemysław Kolek , Institute of Physics, Rzeszów University

Supersonic jet spectra and ab initio modelling of S0→S1 transition of an-thranilic acid molecule

11.35-11.55 OC14

Piotr Kasprzycki , Institute of Experimental Physics, University of Warsaw

Electron localization function, noncovalent interactions analysis and other theoretical tools in photochemistry

11.55-12.15 OC15

Michał Rode, Institute of Physics, Polish Academy of Sciences, Warsaw

Substituent effect on the energetical landscape of the molecular photoswitch

12.15-12.30 Closing remarks

List of Posters


Posters:

P1 Iwona Anusiewicz, Sylwia Freza , Department of Chemistry, University of Gdańsk Superalkalies forming stable molecules with electron acceptors

P2 Marta Brzeska , Institute of Applied Radiation Chemistry, Technical University of Łódź Photodegradation of reactive azo dyes by Advenced Oxidation Proces

P3 Katarzyna Filipczak , Faculty of Chemistry, Adam Mickiewicz University, Poznań Spectral and photophysical properties of individua formed by selected photochromic Schiff bases in the ground and excited states

P4 Sylwester Gawinkowski , Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw SERS studies of porphycene

P5 Mateusz Gierszewski , Faculty of Chemistry, Adam Mickiewicz University, Poznań Spectral and photophysical properties of (E)-N-(alkyl-carbonyl-alhoxy)-2’(4’)-hydroxy-4-stilbazolium halides

P6 Marta Gmurek , Faculty of Process and Environmental Engineering, Technical University of Łódź 2-Chlorophenol photooxidation using meso-tetraphenylporphyrin immobilized into poly-urethane nanofabrics

P7 Aleksander Gorski , Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw Polymorphism in 1H-Pyrrolo[3,2-h]quinoline: experimental and theoretical study

P8 Natalia Gutowska , Faculty of Chemistry, Adam Mickiewicz University, Poznań Spectroscopic properties of individua formed by imidazolium ionic liquids with chloride and tetrafluoroborate anions

P9 Przemysław Kolek , Institute of Physics, Rzeszów University Analysis of the high excited B1

Σ+ Rydberg state in the rare 13C17O isotopic molecule

P10 Przemysław Kolek , Institute of Physics, Rzeszów University Spectroscopy of the B1

Σ+-A1

Π Ångström system in the optical range 19200-21100 cm-1 for the 13C16O isotopic molecule

P11 Dominik Koszelewski , Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw π-Expanded porphyrins - synthesis and photophysics

P12 Ewa Krystkowiak , Faculty of Chemistry, Adam Mickiewicz University, Poznań Hydrogen bonds energy changes upon excitations of aminocoumarins determined from absorption solvatochromic experiment

P13 Aneta Lewkowicz , Institute of Experimental Physics, University of Gdańsk Fluorescent properties of Rhodamine 6G in different xerogel nanolayers and bulk materials

P14 Tomasz Uchacz , Faculty of Chemistry, Jagiellonian University, Kraków New fluorescent sensors based on 1H-Pyrazolo[3,4-b]quinoline skeleton

P15 Alina Majka , Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw Solvent controlled photophysics of siprocyclic lactones

P16 Maria Pszona , Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw Analysis of absorption and emission spectra of Photofrin

P17 Jacek Wierzchowski , Faculty of Food Sci., University of Warmia & Mazury in Olsztyn 8-Azapurines: fluorescent, isosteric alternatives to natural purine bases

P18 Michał Rode, Institute of Physics, Polish Academy of Sciences, Warsaw Substituent effect on the energetical landscape of the molecular photoswitch - poster supplementing oral communication OC15

Plenary Lectures


Plenary Lectures

Opening Lecture


From models to reality: a (very) personal view of p hotoscience

Waluk J.

Institute of Physical Chemistry, Polish Academy of Sciences, [email protected]

A fundamental requirement for each branch of science is to establish general models for the phenomena it deals with, and to apply these models to particular systems. In order to understand elementary photoinduced processes, such as electron, proton, or hydrogen transfer, several model molecules have been studied for such a long time and so intensely that they earned a paradigm status. Using selected examples, I will discuss difficulties, controversies, uncertainties, and pitfalls encountered while studying these “classical” or “standard” systems.

Plenary Lectures


Fig.1 Probability of the solvated electron surviving the geminate recombination in liquid-to-supercritical water as a function of the

temperature and density-dependent dielectric constant.

Ultrafast dynamics of solvated electrons in H-bonde d fluids

Vöhringer P.

1 Institute for Physical and Theoretical Chemistry, University of Bonn

The solvated electron is an elusive transient species whose spectroscopic and dynamical

properties pose until today entirely unresolved and highly intriguing puzzles. Depending on the medium, solvated electron can either be generated chemically (e.g. the ammoniated electron) or they need to be formed via inte-raction of the solvent with ionizing radiation (e.g. the hydrated electron).

In both cases, the detailed nature of the structural motifs of electron binding to the liquid envi-ronment is a controversially debated subject. Does the solvated electron occupy hydrogen-like eigenstates in a „quasi”-spheriodal void of the liquid (i.e. a „cavity” electron) or is it better described as an extended solvent-stabilized

molecular anion cluster (i.e. a molecular species)? Furthermore, the nature of the primary molecular events by which thermalized and fully solvated electrons can be created photolytically are also open to scientific discussions. How can solvated electrons be created with photon energies well below the vertical ionization threshold and at what distances, r0, from the inital ionization site are the excess charges finally in equilibrium with its solvent surroundings? What are the molecular mechanisms and what are their time scales that are involved in electron anni-hilation in the liquid medium?

Our research is targeted at providing experimental insights into these fundamental qu-estions. We use femtosecond time resolved spectroscopy to explore the dynamics of solvation and non-adiabatic relaxation of fully thermalized electrons in response to their ultrafast optical excitation. [1,2] Furthermore, femtosecond multiphoton-ionization with near-infrared probing is used to reveal the dynamics of recombination of the geminate charge carriers including the solvated electron itself. These experiments are carried out on electrons dissolved in hydrogen-bonded solvents over as wide a range of temperature and density thereby covering the liquid and the supercritical phase of the solvent.[3] In combination with detailed numerical calculations including direct-flight Monte-Carlo simulations, this approach also enables us to disentangle the role of the various pathways ultimately leading to electron decay.[4]

[1] J. Lindner, A.-N. Unterreiner, and P. Vöhringer, Chem. Phys. Chem. 7, 363 (2006) [2] J. Lindner, A.-N. Unterreiner, and P. Vöhringer, J. Chem. Phys. 129, 064514 (2008) [3] S. Kratz, J. Torres-Alacan, J. Urbanek, J. Lindner, and P. Vöhringer, Phys. Chem. Chem. Phys. 12, 12169 (2010) [4] J. Torres-Alacan, S. Kratz, and P. Vöhringer, submitted 2011

Plenary Lectures


Semiconductor Visible Light Photocatalysis –

Principles and Applications

Kisch, Horst

Institute of Inorganic Chemistry, University of Erlangen-Nürnberg [email protected]

The chemical conversion and utilization of solar energy is based on light-induced charge

generation and subsequent redox reactions with donor/acceptor molecules. Since relevant substrates usually do not absorb sunlight, a photocatalyst is necessary to enable chemical transformations. Natural photosynthesis is the most important example for such a type of proc-ess. Water is oxidized to oxygen and carbon dioxide to carbohydrates.

Whereas many homogeneous molecular photocatalysts (photosensitizers) may undergo photo-induced charge generation, fast recombination usually prevents efficient redox reactions. This is different is the case of (heterogeneous) semiconductor photocatalysts, wherein the sur-face-trapped are able to simultaneously reduce and oxidize acceptor and donor molecules at the solitd-liquid or solid-gas interphase. In this lecture the following aspects will be discussed [See e.g. ref.1-3].

i) Basic Principles of Semiconductor Photocatalysis

ii) Preparation and Characterization of Semiconductor Powders - Surface Modification of Titania

iii) Controlling the Efficiency of Charge Generation

iv) The Problem of Comparing Apparent Quantum Yields

v) Classification of Semiconductor Photocatalyzed Reactions

vi) Aerobic Photooxidation Reactions for Pollutant Removal

vii) Anaerobic C-N and C-C Coupling Reactions for New Organic Syntheses

viii) Water Cleavage, Nitrogen Fixation, and Activation of Alkanes.

[1] H. Kisch, Adv. Photochem. 62(2001) 93-143.

[2] H. Kisch, W. Macyk, ChemPhysChem 3(2002)399-400.

[3] D. Mitoraj, H. Kisch, Angew. Chem. Int. Ed. 47(2008)1-5.

Plenary Lectures


Photoremovable protecting groups: How fast are they really?

Jakob Wirz

1 Department of Chemistry, University of Basel, Switzerland, [email protected]

Photoremovable protecting groups (PPG’s) provide spatial and temporal control over the re-

lease of various chemicals such as bioagents (neurotransmitters, cell signaling molecules), acids, bases, Ca2+ ions, oxidants, etc. [1–3] The talk will cover recent developments in the field, focusing on reaction mechanisms.

[1] Pelliccioli, A. P.; Wirz, J., Photochem. Photobiol. Sci. 2002, 1, 441. [2] Klán, P.; Bochet, C.; Givens, R. S.; Popik, V.; Wirz, J. Chem Rev., in preparation (2012). [3] Photochem. Photobiol. Sci., Special issue on Photoremovable protecting groups, Feb. 2012.

Plenary Lectures


Excitation energy hopping and photoinduced charge t ransfer pro-

cesses in multichromophoric systems

Eric Vauthey

Department of physical chemistry, University of Geneva, eric.vauthey@unige,ch

Molecular systems containing several identical chromophoric units have found many types of applications, from artificial photosynthesis to DNA detection and molecular electronics. We will present some of our results obtained by ultrafast optical spectroscopy with various multi-chromophoric systems going from molecules with two chromophoric units to more complex systems with up to ten units. We will concentrate on two main processes that can take place in these arrays: excitation ener-gy hopping and charge transfer. The first one is common to most systems and takes place wi-thin a few picoseconds. We will show that the dynamics of energy hopping in a bichromophoric system intercalated into DNA can yield interesting conformational information.[1]

Photoinduced charge separation (CS) between identical chromophoric units is less common and we will discuss some of our efforts to undertand the direction of the charges in such sym-metry-breaking process.[2]

Finally, the excited-state dynamics of multichromophoric systems consisting of eight to ten core-substituted naphtahlenediimide (NDI) chromophores covalently attached to a p- octiphenyl (POP) or an oligophenylethynyl (OPE) scaffold will be discussed. It will be shown that in a lipid bilayer, POP-NDI systems self-organise in a tetrameric architecture allowing photoinduced transmembrane electron transport.[3] Both POP-NDI and OPE-NDI systems also self-assemble on gold surfaces resulting to photocurrent generation.[4] All the CS pathways as well as the ensuing charge recombination (CR) channels have been elucidated.[5,6] Our investigations reve-al that, depending on the nature of the NDI core- substituents and on the scaffold, as well as on the excitation wavelength, either symmetry breaking CS between two NDI moieties or CS be-tween the scaffold and a NDI unit take place. These processes result to charge-separated sta-tes with different lifetimes and thus different efficiencies for photocurrent generation. Although very long-lived charge separation (> ms) was not realised in these systems, this study opens several promising new avenues for ultrafast CS and slow CR.

[1] A. Fürstenberg, M.D. Julliard, T.G. Deligeorgiev, N.I. Gadjev, A.A. Vassilev, E. Vauthey, J. Am. Chem. Soc. 128, 7661 (2006) [2] V. Markovic, D. Villamaina, I. Barabanov, L. M. Lawson Daku, E. Vauthey, Angew. Chem. Int. Ed, 50, (2011), doi:10.1002/anie.201102601. [3] S.A.L. Bhosale, P. Talukdar, A. Fürstenberg, N. Banerji, E. Vauthey, G. Bollot, J. Mareda, C. Röger, F. Würthner, N. Sakai, S. Matile, Science, 313, 84 (2006). [4] A.L. Sisson, N. Sakai, N. Banerji, A. Fürstenberg, E. Vauthey, S. Matile, Angew. Chem. Int. Ed. 47, 3727 (2008). [5] N. Banerji, A. Fürstenberg, S. Bhosale, A.L. Sisson, N. Sakai, S. Matile, E. Vauthey, J. Phys. Chem. B. 112, 8912 (2008). [6] N. Banerji, G. Duvanel, A. Perez-Velasco, S. Maity, N.Sakai, S. Matile, E. Vauthey, J. Phys. Chem. A 113, 8202 (2009).

Plenary Lectures


Intramolecular Charge Transfer in the Excited State .

Dynamics and Structure

Zachariasse K. A.

Max-Planck-Institute for Biophysical Chemistry Spectroscopy and Photochemical Kinetics, Göttingen, Germany, [email protected]

With 4-(dimethylamino)benzonitrile (DMABN) intramolecular charge transfer (ICT) takes place in the excited state,1 with a reaction time of 4 ps in acetonitrile (MeCN) at 25 oC.2 Changing the structure of the amino substituent has a large effect on the ICT reaction, as will be shown for 4-(di-tert-butylamino)benzonitrile (DTABN), 3-(di-tert-butylamino)benzonitrile (mDTABN), 4-(diisopropylamino)benzonitrile (DIABN), and 6-cyanobenzoquinuclidine (CBQ). In addition, new results on ICT with 6-N,N-dialkylaminopurines3 and the six isomers of dicyano-N,N-dialkylaniline are presented. As experimental methods, picosecond time correlated single photon counting (SPC) and femtosecond excited state absorption (ESA) are employed. ICT is also observed in several rigidized molecules: 1-tert-butyl-6-cyano-1,2,3,4-tetrahydroquinoline (NTC6), fluorazene (FPP), and 4-cyanofluorazene (FPP4C). These results show that in such systems, fast ICT to a planar ICT state can take place, on a potential energy surface with a barrier between the initially excited (LE) and ICT states. This means that large amplitude motions such as a perpendicular twist of the amino group are not required for ICT. The electronic coupling between the electron donor and acceptor parts of the molecules appe-ars to be substantial in the ICT state.

[1] Z.R. Grabowski, K. Rotkiewcz, W. Rettig, Chem. Revs. 103, 3899 (2003). [2] S.I. Druzhinin, N.P. Ernsting, S.A. Kovalenko, L.P. Lustres, T.A. Senyushkina, K.A. Zachariasse, J. Phys. Chem. A 110, 2955 (2006). [3] A. Demeter, S.I. Druzhinin, S.A. Kovalenko, T.A. Senyushkina, K.A. Zachariasse, J. Phys. Chem. A 115, 1521 (2011).

Plenary Lectures


Photophysics of hydrogen bonded systems:

from theory to applications

Sobolewski A. L.

Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland, [email protected] Hydrogen bonds are ubiquitous in organic matter. They govern, for example, molecular rec-

ognition in DNA and determine to a large extent the secondary structure of proteins. While the structure and functionality of hydrogen bonds in the electronic ground state have been investi-gated since decades and are thus quite well understood, much less is known on the properties of hydrogen bonds in excited electronic states and on their role in photochemical processes.

We have shown recently that radiationless deactivation channel associated with conical in-tersection (CI) between the electronically excited state and the ground state for proton-transfer reaction along intra- or inter-molecular hydrogen bonds may provide a very effective mechanism for explanation of functionality of commercial organic photostabilizers [1], and the photostability of biological molecules such as DNA [2] and proteins [3], respectively.

In this presentation some potential applications of the above mentioned phenomena will be outlined. Thus the mechanistic aspects of the excited-state intra-molecular proton-transfer (ESIPT) process may be utilized in construction of optically driven photostable molecular switches - (a) [4], while the electron-driven proton-transfer (EDPT) phenomenon along the inter-molecular hydrogen bond(s) may provide a template for designing of macromolecular systems, like Mg-porphyrin (MgP) and benzoquinone (BQ) shown below - (b), which are able to oxidize water using solar (VIS) radiation [5].

(a) (b)

MgP + 2H2O + 2BQ +2hv ---> MgP + O2H2 + 2BQH

[1] A.L. Sobolewski, W. Domcke, C. Hättig, J. Phys. Chem. A 110, 6301 (2006) [2] A.L. Sobolewski, W. Domcke, C. Hättig, Proc. Nat. Acad. Sci. 102, 17903 (2005) [3] D. Shemesh, A.L. Sobolewski, W. Domcke, J. Am. Chem. Soc., 131, 1374 (2009) [4] A.L. Sobolewski, Phys. Chem. Chem. Phys, 10 (2008) 1243 [5] A.L. Sobolewski, W. Domcke, J. Phys. Chem. A 112, 7311 (2008)

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Invited Lectures


Invited Lectures

Invited Lectures


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Scheme 1. Different reaction pathways for diazo ketones.

Ultrafast time-resolved studies of Wolff rearrangem ent process

Burdziński G.

Faculty of Physics, Adam Mickiewicz University, Poznań, [email protected]

Photochemical Wolff rearrangement process of diazo carbonyl compounds in solution has

been extensively studied by ultrafast transient absorption spectroscopy with UV–Vis and mid-IR detection with the aid of modern computational methods [1]. Two paths of Wolff rearrangement reaction should be considered: stepwise (carbene mediated) and concerted. The latter means that product is formed in the diazo singlet excited state in concert with molecular nitrogen extrusion. Accordingly to Kaplan and Meloy’s rule [4], proposed over 40 years ago, concerted Wolff rearrangement process is favored in the syn conformers of α-diazo carbonyl compounds, while the light activation of anti conformers promotes

the stepwise process. Our ultrafast UV-vis and IR results [1-3] for acyclic diazo carbonyl compounds (diazoacetone, azibenzil, p-biphenyl methyldiazo ketone) agree with Kaplan and Meloy’s rule. Since typical lifetime of diazo singlet excited state is less than 0.3 ps, concerted process can be confirmed by a fast product rise (< 0.3 ps). The stepwise process with carbene intermediacy results in a slower product rise (> 1 ps) depending on carbene lifetime. The excess of vibrational energy in the nascent carbene species can be also an important factor increasing the rate of carbene-ketene isomerization process. The short (< 0.3 ps) lifetime of the diazo excited state may also indicate that the syn and anti forms produced with UV light pulse do not interconvert, thus the photochemistry proceeds from the

Franck-Condon state. Recently hetero Wolff rearrangement process has been studied by time-resolved spectroscopy, formation of thioketene and thiirene intermediates has been observed for 1,2,3-thiadiazoles.

[1] G. Burdzinski, M. Platz, J. Phys. Org. Chem. 23, 308 (2010) [2] G. Burdzinski, Y. Zhang, J. Wang, M. Platz, J. Phys. Chem. A 114, 13065 (2010) [3] G. Burdzinski, J. Wang, T. Gustafson, M. Platz, J. Am. Chem. Soc. 130, 3746 (2008) [4] F. Kaplan, G. Meloy, J. Am. Chem. Soc. 88, 950 (1966)

Invited Lectures


100 200 300 400

T

A(H2O)

n

ion mass (u)

A2(H

2O)

n

*

0 1 2 3 4

x20

elec

tron

s

electron kinetic energy (eV)

IPad = 8.0 eV

0 2 4 100 200 pump-probe delay (ps)

ions

τ ≈ 0.1, 1.3, 1000 ps

Fig.1 (adapted from [1]) Femtosecond time-resolved mass and electron spectroscopy of biomolecular clusters. A species of interest (e.g. the microhydrated base pair adenine2-(H2O)3) is identified in the mass spec-trum (left) and relevant excited state processes are analysed via corre-lated time-resolved mass (top right) and electron spectra (bottom right).

Ultrafast Spectroscopy of Biomolecules and Clusters

Thomas Schultz1

1Max Born Institute Berlin, [email protected]

Chemical reactions involve the breaking and forming of chemical bonds between atoms. The speed of such transformations is limited by the timescale of nuclear motion along the reaction coordinate. With femtosecond time-resolved spectroscopy, chemical reactions can be observed in real time and the pathway from educt to product can be characterized. We combine gas-phase spectroscopy and high-level theory to resolve the mechanism of excited state processes in isolated biomolecules. In their native environment, however, the biomolecules interact with a local envi-ronment (typi-cally water or other bio-molecules). Whether gas-phase results offer relevant contributions to-wards the understanding of real biological systems is therefore heavily dis-puted. We bridge the gap between the isolated and the solvated species with experiments on isolated molecules, microhydrated clusters, and species in a liquid water jet. With pump-probe ionization experiments for all spe-cies, we strive to identify the photochemical pro-cesses within and without the local environment.

The information content of spectroscopy is always limited by the spectroscopic resolution and, according to the Heisenberg uncertainty principle, the energy resolution cannot exceed ∆E⋅∆t ≥ h. In femtosecond pump-probe experiments, this limit is quite severe because the ob-servation time ∆t is limited by the femtosecond duration of the laser pulses. Hence, the informa-tion content of femtosecond experiments does not scale favorably for the investigation of larger molecules with many degrees of freedom, and is insufficient to characterize the structure of larger biomolecules or clusters. A novel technique of correlated rotational alignment spectros-copy (CRASY, [2]) combined high-resolution rotational spectra with femtosecond pump-probe data and will help the investigation of systems with more complex structure in the future.

[1] V.R. Smith, E. Samoylova, H.-H. Ritze, W. Radloff, T. Schultz, PCCP 12, 9632 (2010). [2] Christian Schröter, Kyriaki Kosma, Thomas Schultz, SCIENCE 333, 1011 (2011).

Invited Lectures


Coordination compounds as photosensitizers of titan ium dioxide

Wojciech Macyk

Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland

e-mail: [email protected]

Photochemistry of coordination compounds in solutions is very often related to homo-geneous photocatalytic processes. Small molecules activation, photoinduced redox reactions or ligand substitution are common examples of light-driven processes involving metal complexes. Change of the oxidation state of metal ion elicited by charge transfer excitation is usually a key-step initiating a photocatalytic process. Photoinduced charge transfer processes, involving cen-tral atom of a complex, take place in heterogeneous photocatalysis, also that based on titanium dioxide. Already TiO2 excitation can be considered as a ligand to metal charge transfer, in which electron is transferred from the ligand (O–II) to titanium center (TiIV). As a result the oxidized ligand (O–I, i.e. hole in the valence band) and reduced titanium (TiIII, i.e. electron in conduction band) are formed. Similarly, photosensitization of TiO2 by metal complexes (of ruthenium, plati-num, iron, titanium and others) characterized by CT bands and suitable redox properties, plays a key-role in modern heterogeneous photocatalysis.

Photosensitization may proceed according to various mechanisms involving physical (e.g. light absorption, intersystem crossing, etc.) and chemical (e.g. redox reactions, ligand substitution, rearrangements, etc.) processes. Usually, a photoinduced electron injection from the excited state of the photosensitizer to conduction band of TiO2 plays a crucial in these mechanisms. Titanium dioxide is then reduced while the photosensitizer is oxidized. However, the photosensitizer in its excited state is a stronger reductant and oxidant at the same time. Is then a process of photosensitization, involving TiO2 oxidation by excited photosensitizer, possi-ble at all? Can we use photochemistry of coordination compounds in solution to describe proc-esses governing the heterogeneous photocatalysis? These aspects related to photosensitiza-tion of TiO2, as well as photochemistry and photophysics of coordination compounds, will be discussed during the presentation.

References [1] H. Kisch, W. Macyk, Visible-light photocatalysis by modified titania, ChemPhysChem 3, 399-400

(2002) [2] K. Szaciłowski, W. Macyk, A. Drzewiecka-Matuszek, M. Brindell, G. Stochel, Bioinorganic photochem-

istry. Frontiers and mechanisms, Chem. Rev. 105, 2647-2694 (2005) [3] G. Stochel, M. Brindell, W. Macyk, Z. Stasicka, K. Szaciłowski, Bioinorganic Photochemistry (Wiley,

Chichester, 2009) [4] K. Szaciłowski, W. Macyk, M. Hebda, G. Stochel, Redox-controlled photosensitization of nanocrystal-

line titanium dioxide, ChemPhysChem 7, 2384-2391 (2006) [5] W. Macyk, K. Szaciłowski, G. Stochel, M. Buchalska, J. Kuncewicz, P. Łabuz, Titanium(IV) complexes

as direct TiO2 photosensitizers, Coord. Chem. Rev. 254, 2687-2701 (2010) [6] J. Kuncewicz, P. Ząbek, G. Stochel, Z. Stasicka, W. Macyk, Visible light driven photocatalysis in

chromate(VI)/TiO2 systems – improving stability of the photocatalyst, Catal. Today 161, 78-83 (2011)

Invited Lectures


Novel π-expanded porphyrins – synthesis and photophysics

Daniel T. Gryko,*,1,2 Agnieszka Nowak-Król,1 Dominik Koszelewski,1 Aleksander Re-

bane,3 Mikhail Drobizhev,3 and Erich Beuerman3

1Institute of Organic Chemistry of the Polish Academy of Sciences, Warsaw, Poland 2Warsaw University of Technology, Faculty of Chemistry, Warsaw, Poland

3Department of Physics, Montana State University, Bozeman, MT 59717, USA

Optical limiting is a nonlinear effect consisting of a decrease in the transmittance of the NLO material under high-intensity illumination. Among different functions optical limiting devices can perform, the most useful one is the protection of optical elements, sensors and human eye against damage by exposure to a sudden high-intensity light. Dipolar or quadrupolar aromatic molecules have been shown to be of particular interest since they allow combining very fast (femtoseconds) intrinsic two-photon absorption (2PA) with somewhat slower reversed saturable absorption (RSA).

We have developed the general principle to design porphyrins possessing low melting-point and we synthesized first liquid porphyrins: 5,10,15,20-tetrakis[3,4,5-tris(decyloxy)phenyl]porphyrin and 5,10,15,20-tetrakis[3,4,5-tris(undecyloxy)phenyl]porphyrin. We also developed conceptually new strategy towards π-expansion of porphyrin ring, which relies on anion-radical coupling of suitable meso-substituted metallated porphyrins. Very recen-tly we discovered the superior reagent for carrying out intramolecular oxidative coupling of por-phyrins which avoids formation of troublesome side-products. All these developments combined with liquid porphyrin principle allowed us to produce first liquid porphyrin possessing large two-photon absorption cross-section – suitable for optical limiting.

Invited Lectures


Photomodification of corrole molecules

Mackowski S.

Institute of Physics, Nicolaus Copernicus University, Toruń, [email protected]

Corroles are synthetic, aromatic macrocycles of tetrapyrrolic family that also includes por-

phyrins and phthalocyanine. Interest in these compounds has grown recently as these mole-cules could be potentially used for antitumor therapy, catalytic and optical sensor devices, and artificial light-harvesting systems.

In this work we describe the optical properties of 5,10,15-tris(pentafluorophenyl)corrole, one of the most studied member of this family. Two particular aspects will be discused in detail. Firstly, we demonstrate that upon illumination with a UV light, the corrole undergoes strong photomodification: new emission bands appear which are characterized with different fluores-cence decay times. This effect depends strongly upon the excitation power and is absent when the corrole is excited with 532 green laser. Possible sources of this highly surprising effect will be speculated about.

Secondly, we coupled corrole molecules with plasmon excitations in single silver nanowires in an attempt to describe the effect of plasmons upon the optical properties of the corrole. Us-ing our home-built confocal fluorescence imaging microscope we can determine the position of the nanowire and correlate it precisely with the fluorescence image. The result of this work show that we can strongly enhance the fluorescence intensity of corrole emission via plasmon excitation.

Research at NCU has been supported by the WELCOME project “Hybrid Nanostructures as a Stepping Stone towards Efficient Artificial Photosynthesis” funded by the Foundation for Pol-ish Science and EUROCORES project “BOLDCATS” funded by the European Science Founda-tion.

This work has been carried out in collaboration with the groups of Daniel Gryko (Warsaw) Nicholas A. Kotov (Ann Arbor), and Wolfgang Heiss (Linz).

Invited Lectures


Electron transfer and diffusion

Angulo G.1

1 Institute of Physical Chemistry, Polish Academy of Sciences, [email protected]

Many researchers will tell you that everything about electron transfer has already been said. Many will tell you that diffusion in solution is perfectly understood. Despite their opinion I will show in this seminar that none of the former statements is true. More-over, I will show that a kuhnian revolution1 is on-going since the appearance of Encoun-ter Theories (ET)2 and that this research programme is progressive, in terms of Lakatos3. This theoretical corpus is intended to deal with any kind of reaction and its modulation by the diffusion of the reaction partners.

We will discuss the basics of electron transfer from the Marcus point of view4. Then an introduction to diffusion in solution will be presented along with the ET that match re-activity between freely moving independent reactants and their mobility. Afterwards, several experiments will show our attempts to unsuccessfully falsify the theory, in the popperian sense5. These comprise studies of fluorescence quenching6 and ions recom-bination7 as well as the dependence of both on the viscosity of the medium, the driving force of the reaction and on the concentration of the quencher. Additionally, experiments at very high quencher concentrations will be explained by articulating the theory to con-sider the rotational effects on the reaction8 –which to our knowledge is the first example of such behaviour since Rice stated the difficulties to observe them9. The progressive character of the ET will be finally demonstrated by showing new experiments on the de-pendence of the quenching rate coefficient on the excitation light intensity10.

Nevertheless, do not forget that “not only are facts and theories in constant disharmony, they are never as neatly separated as everyone makes them out to be”11.

[1] T. S. Kuhn The Structure of Scientific Revolutions (1962). [2] A.I. Burshtein Adv. Chem. Phys. 2000, 114, 419. Ibidem 2004, 129, 105. [3] I. Lakatos The Methodology of Scientific Research Programmes: Philosophical Papers Volume 1 (1978). [4] R.A. Marcus J. Chem. Phys. 1956, 24, 966; J. Chem. Phys. 1956, 24, 979; J. Chem. Phys. 1957, 26, 867; Discuss. Faraday Soc. 1960, 29, 21; Ann. Rev. Phys. Chem. 1963, 15, 155. [5] K. Popper Conjectures and Refutations: The Growth of Scientific Knowledge (1963). [6] A. Rosspeintner, D. R. Kattnig, G. Angulo, S. Landgraf, G. Grampp, A. Cuetos Chem. Eur. J. 2007, 13, 6474. A. Rosspeintner, D. R. Kattnig, G. Angulo, S. Landgraf, G. Grampp Chem. Eur. J. 2008, 14, 6213. G. Angulo, D.R. Kattnig, A. Rosspeintner, G. Grampp, E. Vauthey Chem. Eur. J. 2010, 16, 2291. [7] G. Angulo, G. Grampp, A.A. Neufeld, A.I. Burshtein J. Phys. Chem. A 2003, 107, 6913. V.S. Glad-kikh, A.I. Burshtein, G. Angulo, G. Grampp PCCP 2003, 5, 2581. [8] To be published. [9] S.A. Rice Diffusion-Limited Reactions, in Comprehensive Chemical Kinetics 25, Bramford, C.H., Tip-per, C.F.H.; Compton, R.G. Eds.; Elsevier, Amsterdam, 1985. [10] P.K. Feyerabend Against Method: Outline of an Anarchistic Theory of Knowledge (1975).

Invited Lectures


Unusual Oxidizing Agents

Skurski P.1

1 Department of Chemistry, University of Gdańsk, [email protected]

The possibility of utilizing superhalogen molecules as strong oxidizing agents (electron ac-

ceptors) capable of forming stable compounds with moderately reactive or chemically inert systems is demonstrated and discussed on the basis of theoretical considerations supported by ab initio calculations.

The provided discussion covers the explanation of the hypothetical HAlCl4 acid instability (the existence of the corresponding LiAlCl4, NaAlCl4, and KAlCl4 salts was confirmed whereas their parent acid (HAlCl4) was identified as the HCl···AlCl3 adduct with the hydrogen chloride moiety tethered weakly to the quasi-planar aluminum chloride molecule). As concluded, the electron binding energy (VDE) of the neutral superhalogen AlCl4 molecule was the most impor-tant factor determining the ability to form a stable MAlCl4 compound (M=Li, Na, K). This finding was further confirmed by demonstrating that the competition between the ionization potential (IP) and VDE values is indeed a key factor for predicting the stability of certain novel species (such as MgBX5, X=F, Cl). Namely, the reason why the MgBX5 molecules (which might be con-sidered as composed of the MgX and BX4 fragments) are kinetically and thermodynamically stable is the proper balance between the IP of the MgX moiety and the BX4 ability to accept an excess electron (manifested by the VDE of its anionic daughter). Finally, it is demonstrated that almost any neutral molecule (including those regarded as nearly non-reactive) might be assem-bled into a stable, strongly bound compound when combined with a properly designed superha-logen system. Moreover, it is shown that such a resulting compound exhibits partially ionic character as its stability is a consequence of the substantial electron density flow to the oxidiz-ing agent used.

In general, the results show the ability of the superhalogen systems to ionize even the mole-cules that are not commonly considered to act as the reducers. In other words, due to their unusual properties, the superhalogens may act as enormously strong oxidizing agents capable of forming stable ionic compounds when combined even with moderately reactive chemical systems.

Panel Discussion


Panel Discussion

Photoinduced Charge Transfer and Conformational Changes

Panel Discussion


Panel Discussion: Photoinduced Charge Transfer and Conformational Cha nges

Grabowski Z. R.

Dear photochemical friends,

I am sorry to be unable – for health reasons – to attend the meeting. It is already nearly 40 years as I entered the EPA, being the first member from this side of the iron curtain. EPA has been affiliated with the European Union, and therefore suspected by the one-time authorities to be a Trojan horse of the West. It was really difficult to legalize the Polish Section of EPA. It appeared much more difficult afterwards to establish EPA in other countries of the Eastern Block.

EPA turned to be like a large and friendly family – in a broad cooperation in research, in education, and even in form of a mutual help in the need. In Poland we experienced – in a memorable way – the help from our photochemical friends when the martial law was imposed in 1981.

* * * The development of photochemistry went generally from simple objects – atoms, diatomic

molecules – to the most complex biological structures or processes, and so called nanoparticle multiphase systems from one side, to the single molecules on the other. Most advanced meth-ods of theory and experiment are used, with enormous success. Nevertheless, even the photo-chemistry of rather simple molecules presents still a challenge for research and for imagination.

One is usually expecting the simplest and fastest photochemical reactions in solutions should be the electron and proton transfer. Pro-tolytic (acid-base) reactions belonged to the earliest not only detected, but also well understood from the mechanistic and kinetic points of view. We owe it to Theodor Förster and Albert Weller. Much later, the excited state intra-molecular proton transfer reactions (ESIPT, photo-tautomerisations) revealed that the excited state molecular structure suitably modifies in the proton transfer reaction, and the molecular vibrations which promote the reaction are identified.

Half a century ago Ernst Lippert and his students discovered a molecule (DMABN) which emits double fluorescence in absence of any reaction partner. The ratio of intensity of the two bands, strongly de-pendent on the polarity of the solvent, indicated to an excited state reaction accompanied with a huge increase of the dipole moment. It was an intramolecular electron transfer (ICT) reaction. Hypotheses concerning the nature of the chemical change responsible for this dual fluores-cence phenomenon and its applications multiplied with time, and the number of related papers is already counted in thousands. Just to name a few: an inversion of states [Lippert]; excimer formation [McGlynn; Mataga]; hydrogen bonding [Kosower; Cazeau-Dubroca]; exciplex with the solvent [Chandross; Varma]; our hypothesis on the ~90o twist of the donor vs acceptor units (zwitterionic biradical, twisted ICT state – TICT).

In our group, we synthesized a number of D-A analogs of DMABN, specially those with a structure compelling the D and A units to be mutually twisted or rigidly coplanar already in the ground state. This model gained much support, both from numerous theoretical calculations and from new experimental methods.

NCH3H3C

C

N

DMABN

Panel Discussion


Paralel, however, there appeared an opposite view [Zachariasse] claiming the structural

change in the ICT state is toward a planar structure. This gained also much evidence, specially in cases of various larger derivatives or analogs of DMABN. Also in our group it has been shown [Herbich & Kapturkiewicz] that the compounds with a dialkylamino group as a donor, and a larger aromatic system as acceptor, in the ICT state tend to be planar.

Hypothetical models multiplied, including structural changes of the donor or in the acceptor unit. Moreover, it is shown that the structure of the benzene ring undergoes a quinoid or an-tiquinoid deformation in the excited states involved [Haas & Zilberg].

With respect to DMABN and its monocyclic analogs more and more refined methods were applied, specially the picosecond and femtosecond time-resolved IR and resonance Raman spectroscopy [i.a., Ma, Kwok & al.], in general supporting the TICT model. As a decisive proof we considered the ingenious NMR experiment [Dobkowski, Waluk, Michl, & al.] which has shown that the molecule in the ICT state passes through the 90o twist.

Nevertheless, new and unexpected findings revived the discussion on the ICT state of DMABN: theoretical and experimental findings on the existence of a previously not considered πσ* state and its role in the electron transfer [Sobolewski and Domcke; Lim & al.]. Even the kinetics became an unsolved mystery – the decay of the ICT fluorescence and of its transient absorption are claimed to be different…

My conclusion is that the insight into the nature and mechanism of the photochemical proc-esses of even simple molecules offers still very many riddles and much inspiration to our imagi-nation and research.

Let this meeting will help and inspire you !

Zbigniew R. Grabowski

Panel Discussion



Zachariasse K. A.

Max-Planck-Institute for biophysical Chemistry

Spectroscopy and Photochemical Kinetics,Göttingen, Germany, [email protected]

The occurrence of photoinduced intramolecular charge transfer (ICT) with electron do-nor(D)/acceptor(A) substituted benzenes, such as 4-(dimethylamino)benzonitrile (DMABN), is mainly determined by the magnitude of the energy gap ∆E(S1,S2) between the two lowest exci-ted singlet states. In the final ICT state, the D and A moieties are not electronically decoupled, as, i.a., seen from the observation that this ICT state is fundamentally different from intermole-cular exciplexes, with weakly coupled D and A subunits. This follows from the finding that the energy E(ICT) can not be calculated from the redox potentials of D and A, in contrast to the exciplexes. Examples are, the absence of an ICT reaction with 4-(methylamino)benzonitrile (MABN) and the photophysical behaviour of the six dicyano-N,N-dimethylanilines (mnDCMAs).1 With these mnDCMAs, an ICT reaction only takes place for the isomers with the smallest ∆E(S1,S2), notwithstanding the strongly enhanced electron affinity of dicyanobenzene (mnDC-MAs) as compared with benzonitrile (DMABN). A perpendicularly twisted amino group is only found with the ICT states of DTABN, mDTABN, and CBQ, rigidized molecules that are chemi-cally forced into this unnatural twist. For an understanding of the excited state absorption spec-tra of aminobenzonitriles is should be realized that the absorption spectra of the radical anions of substituted benzonitriles hardly depend on the nature of the substituents. Looking back at the discussions on this topic, for a long time it was taken for granted that the ICT state of the D,A-substituted benzenes has a perpendicularly twisted amino group, without feeling the necessity to support this belief by experimental evidence. It then became apparent that it is very difficult to disprove such a belief. Max Planck2 already remarked in 1946 that it rarely happens that scientists change their opinions.

[1] V.A. Galievsky, S.I. Druzhinin, A. Demeter, S.A. Kovalenko, T.A. Senyushkina, P. Mayer, K.A. Zachariasse, J. Phys. Chem. A 115, 000 (2011) [2] M. Planck, Naturwissenschaften 33, 230 (1946): „Persönliche Erinnerungen aus alten Zeiten“

Panel Discussion



Excited state twisting: a rule or an exception?

Waluk J.


The fate of excited 4-(dimethylamino)benzonitrile remains a subject of never-ending discus-sions [1]. The bone of contention is the geometry of the molecule and its electronic structure.

It now seems that loss of planarity upon electronic excitation is quite common and important as a trigger for efficient radtiationless depopulation. Based on our recent work [2], I will present several examples of molecules in which excited state proton transfer seems to be accompanied by twisting.

[1] T. Fujiwara, M. Z. Zgierski, E. C. Lim, Phys. Chem. Chem. Phys. 13, 6779 (2011), and references therein. [2] E. Nosenko, G. Wiosna-Sałyga, M. Kunitski, I. Petkova, A. Singh, W. J. Buma, R. P. Thummel, J. Waluk, Angew. Chem., Int. Ed. Engl. 47, 6037 (2008).

Panel Discussion


Oral Communications


Oral Communications

Oral Communications


Fig.1 (a) Transient IR spectra produced by photolysis of 2-NpSO2N3 in CCl4 (λexc=330 nm). (b) Transient kinetics observed at the 2083 cm-1 (the S1 state decay) and at the

2129 cm-1 (the ground state recovery).

Direct observation of sulfonyl azide excited state and its decay

processes by ultrafast time-resolved IR and UV-Vis spectroscopy

Jacek Kubicki

Adam Mickiewicz University, Faculty of Physics, Poznań, Poland, [email protected]

Recently the early stages of photolysis of acyl azides and phosphoryl azide were studied by ultrafast spectroscopy.1-3 The mechanism of nitrene formation and Curtius rearrentment has

been investigated. It was shown that both singlet nitrene and isocyanate are formed directly from the S1 excited state of azide.1-3 These results motivated us to study the photochemistry of sulfonyl azide with ultrafast spectroscopy. 2-Naphthyl sulfonyl azide (2-NpSO2N3) was chosen in this study as it has a convenient chromophore for UV-vis excitation. In addition, calculations predict that the singlet and triplet states of 2-NpSO2N3, the singlet and triplet states of nitrene 2-NpSO2N, and the pseudo Curtius rearrangement photoproduct 2-NpNSO2 all have relatively intense IR markers, which make this compound an ideal target for ultrafast IR study. Photolysis of 2-NpSO2N3 with 330 nm excitation promotes 2-NpSO2N3 directly to the S1 state, which was observed at the 2080 cm-1 by ultrafast IR spectroscopy (Fig. 1) and in 350-650 nm spectral range by ultrafast UV-vis spectroscopy. To our best knowledge this is the first direct observation of the S1 state of sulfonyl azides. It was found that internal conversion is a major deactivation process of the S1 state while intersystem crossing brings only minor contribution. The S1 state decays also to singlet nitrene and undergoes concerted pseudo Curtius rearrangement. Singlet sulfonyl nitrene is short-lived species and it decays to triplet nitrene via intersystem crossing. The assignments of species detected experimentally are consistent with quantum chemical calculations and matrix studies.

The project was performed in collaboration with Drs. Matthew S. Platz and Christopher M. Ha-dad’s research groups at the Chemistry Department of The Ohio State University.

[1] Kubicki, J.; Zhang, Y.; Wang, J.; Luk, H. L.; Peng, H.-L.; Vyas, S.; Platz, M. S. J. Am. Chem. Soc. 131, 4212 (2009) [2] Kubicki, J.; Zhang, Y.; Vyas, S.; Burdzinski, G.; Luk, H. L.; Wang, J.; Xue, J.; Peng, H.-L.; Pritchina, E. A.; Sliwa, M.; Buntinx, G.; Gritsan, N. P.; Hadad, C. M.; Platz, M. S. J. Am. Chem. Soc. 133, 9751 (2011). [3] Vyas, S.; Muthukrishnan, S.; Kubicki, J.; McCulla, R. D.; Burdzinski, G.; Sliwa, M.; Platz, M. S.; Ha-dad, C. M. J. Am. Chem. Soc. 132, 16796 (2010)

Oral Communications


Fig.1. Scheme of proton transfer cycle in 2-(2-pyridyl)pyrrole

2-(2-Pyridyl)pyrrole: coupling of photoinduced elec tron/proton

transfer with conformational changes

Michał Kijak1, Wybren Jan Buma2, Ivo van Stokkum2, Jacek Waluk1

1 Institute of Physical Chemistry, Polish Academy of Sciences, [email protected] 2 Institute of Molecular Chemistry, University of Amsterdam

Intramolecular excited state proton transfer in 2-(2-pyridyl)pyrrole1-3 has been studied by

time-resolved spectroscopy techniques. Femtosecond/picosecond transient absorption and emission measurements reveal the sequence of fast events that occur after photoexcitation. The flow of electronic density from the pyrrole to the pyridine moiety is followed by proton trans-fer to the pyridine nitrogen. Due to large differences in excited state dipole moments between the initial and final tautomeric forms, the barrier and rate of phototautomerization vary strongly with solvent polarity. The tautomeric form is unstable and decays faster than it is formed, possi-bly by way of twisting (Fig.1). The ground state tautomeric species is detected and assigned on the basis of the mirror relationship to the phototautomeric emission. Density functional theory molecular modelling of the reaction in the ground and the excited state confirms the above scheme and suggests that twisting in the excited tautomer can be active in the efficient radia-tionless transition.

[1] M. Kijak, A. Zielinska, C. Chamchoumis, J. Herbich, R. P. Thummel, J. Waluk, Chem. Phys. Lett. 400, 279 (2004) [2] M. Kijak, Y. Nosenko, A. Singh, R. P. Thummel, J. Waluk, J. Am. Chem. Soc. 129, 2738, (2007) [3] M. Kijak, Y. Nosenko, A. Singh, R. P. Thummel, B. Brutschy, J. Waluk, J. Mol. Struct. 844, 286, (2007)

Oral Communications


The ground- and excited-state double proton transfe r in alloxazine

and some of its derivatives: Theoretical and experi mental approach

Sikorski M.1, Dobek K.1, Hoffmann M.1, Ferreira L.F.V.2, Sikorska, E.3

1 A. Mickiewicz University, Poznań, Poland, [email protected] 2 Universidade Técnica de Lisboa, Lisboa, Portugal 3 Poznań University of Economics, Poznań, Poland

Our recent work on excited-state double proton transfer (ESDPT) focussed on lumichrome = 7,8-dimethylalloxazine = 7,8-dimethyl-benzo[g]pteridine-2,4(1H,3H)-dione, a representative of alloxazines. Acetic acid acts as a catalyst for the ESDPT reaction in lumichrome, as its own structure remains unchanged upon ESDPT in e.g. acetic acid/lumichrome complex [1,2], while ESDPT in the lumichrome dimer changes the structure of both molecules [3]. Quantum-mechanical calculations confirm that ESDPT in the lumichrome-acetic acid complex is a con-certed process [2,4], predicting proton transfer leading to an energy minimum (cation-anion pair) in the lumichrome dimer [3].

The data obtained for a series of fourteen alloxazine derivatives, clearly indicate significant substituent effects on the alloxazine photophysics. Thus, 6,7-dimethyl-alloxazine, 6-methyl-alloxazine, 7-methyl-alloxazine, and their respective 1-methyl substituted derivatives were cho-sen for the ESDPT studies. Such choice of molecules enabled to study the effect of the first

excited state configuration, 1(n, π)* over 1(π,π)*, modulated by the electronic structure of the alloxazine and affected by the solvent choice, the effect of the hydrogen bond environment on the ESDPT, and the solvent polarity effect. The ESDPT was structurally prevented in 1-methyl-substituted alloxazines, however, a clear effect of substituent position on ESDPT was notice-able comparing 6,7-dimethyl-alloxazine to 7,8-dimethylalloxazine. Steady-state and time-resolved fluorescence and absorption results were performed at 298K and 77K. Single-photon timing was used to measure the emission lifetimes. These results confirm formation of an isoal-loxazinic excited state via ESDPT catalyzed by a carboxylic acid molecule forming a hydrogen-bonded complex with the parent alloxazine. Experimental results were supported by quantum-mechanical calculations: the calculated activation barrier in the excited state is much lower than that in the ground state. Additionally, flash photolysis was used to explore ESDPT in triplet states, with negative results.

References

[1] Sikorska, E., Khmelinskii, I. V., Prukala, W., Williams, S. L., Patel, M., Worrall, D. R., Bourdelande, J. L., Koput, J., Sikorski, M. J. Phys. Chem. A 2004, 108, 1501. [2] Sikorska, E., Khmelinskii, I. V., Hoffmann, M., Machado, I. F., Ferreira, L. F. V., Dobek, K., Karolczak, J., Krawczyk, A., Insinska-Rak, M., Sikorski, M. J. Phys. Chem. A 2005, 109, 11707. [3] Sikorska, E., Khmelinskii, I. V., Kubicki, M., Prukala, W., Hoffmann, M., Machado, I. F., Ferreira, L. F. V., Karolczak, J., Worrall, D. R., Krawczyk, A., Insinska-Rak, M., Sikorski, M. J. Phys. Chem. A 2006, 110, 4638. [4] Sikorska, E., Koziolowa, A., Sikorski, M., Siemiarczuk, A. J. Photochem. Photobiol. A 2003, 157 (1), 5-14.

Oral Communications


Photoactive titanium dioxide coatings on organic po lymers

Rafał Sadowski, Wojciech Macyk

Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland e-mail: [email protected]

Nonsocomial infections also called “hospital acquired infections” are one of the major

problems of modern medicine. They contribute to mortality and morbidity thereby increasing health care costs [1]. Course of infections can be different but most of them are related to the infection through medical polymers. Currently, the most important trend is focused on the design of materials with anti-infective properties. Many research programs are focused on the modification of polymer surface by using additives and/or copolymerization processes in order to change surface properties without changing the polymer in its bulk. In general, surface treatments can be divided into three categories: chemical, thermal and electrical. The most promising is modification by plasma induced in various gases. Such elctrical treatment allows generation of surface radicals and ionic groups which improve film wettability and change surface chemistry, opening a possibility of binding various antibacterial agents. Also some photocatalytic coatings can be used as antimicrobial agents. Among others TiO2 shows a high activity in photodynamic inactivation of bacteria with the benefits of its physical and chemical stability, low toxicity, bio-compatibility and cheapness [2-4].

Two types of commercially available polyurethane foils (Bayer) were used in our studies as supports for titanium dioxide films. Each foil was pretreated with various types of plasma and covered with titanium dioxide thin film by spin- and dip-coating techniques. Also other methods, involving no plasma activation, have been applied in synthesis of TiO2 layers. Afterwards the films were photosensitized by titanium(IV) surface complexes formed upon impregnation with catechol-like ligands [5]. The quality, involving stability and photocatalytic activity of prepared films, were compared. The results of these tests will be presented and discussed.

Acknowledgement This study is a part of PhD work of RS within Interdisciplinary PhD-studies “Molecular

science for medicine” financed by Human Capital Operational Programme.

[1] G. Ducel, J. Fabry, L. Nicolle et al., Prevention of hospital-acquired infection, a practical guide, 2nd edition (World Health Organization, Malta, 2002)

[2] W. Su, S. Wang, X. Wang, X. Fu, J. W, Plasma pre-treatment and TiO2 coating of PMMA for the im-provement of antibacterial properties, Surface & Coatings Technology 205, 465-469 (2010)

[3] M.R. Sanchis, O. Calvo, O. Fenollar, D. Garcia, R. Balart, Characterization of the surface changes and the aging effects of low-pressure nitrogen plasma treatment in polyurethane film, Polymer Testing 27, 75-83 (2008)

[4] S. Sartori, A. Rechichi, G. Vozzi, M. D’Acunto, E. Heine, P. Giusti, G, Ciardelli, Surface modification of a synthetic polyurethane by plasma glow discharge: Preparation and characterization of bioactive monolayers, Reactive & Functional Polymers 68, 809-821 (2008)

[5] W. Macyk, K. Szaciłowski, G. Stochel, M. Buchalska, J. Kuncewicz, P. Łabuz, Titanium(IV) complexes as direct TiO2 photosensitizers”, Coord. Chem. Rev. 254, 2687-2701 (2010)

Oral Communications


Photophysical and electrochemical features of semic onductors

modified with polynitriles

Marek Oszajca1, Matteo Amelia2, Alberto Credi2, Konrad Szaciłowski1,3

1. Photochemistry of Coordination Compounds and Bioinorganic Chemistry Group, Institute of Chemistry, Jagiellonian University, Ingardena 3, 30-060, Kraków, Poland,

2. Dipartimento di Chimica ‘‘G. Ciamician’’, Universita di Bologna, via Selmi 2 - 40126 Bologna, Italy

3. Faculty of Non-Ferrous Metals, AGH University of Science and Technology, A. Mickiewicza 30, 30-059 Kraków, Poland [email protected]

Cyanocarbon acids synthesized by Middleton et al. in 1950s are derivatives of the well known organic electron acceptor – tetracyanoethylene (TCNE) [1]. TCNE and its three derivatives were examined: 1,1,2,3,3-pentacyanoprop-2-en-1-ide, bis(tricyanoethenyl)-azanide and bis(tricyanoethenyl)diazanediide (Figure 1). Inten-ded as a new class of pigments, these compounds have found little attention in photoelectrochemi-stry. Their linear structure make them capable of reaching the surface of semiconducting quantum dot (QD) more easily than aromatic ring based electron acceptors e.g. tetracyanoquinodimethane (TCNQ). The reversible electrochemistry of TCNE and its derivatives enhances the efficient quen-ching of the QD excited state. In case of TCNE new absorption band was formed, due to forma-tion of charge-transfer complex between TCNE and QD. Further photoelectrochemical studies revealed that modifying QD surface with TCNE and its derivatives significantly enhances generation of the photocurrents. In addition, the direction of the photocurrent could be switched from cathodic to anodic and the other way round by application of adequate external potential. The photo-electrochemical properties of those materials allow construction of optoelectronic logic gates via the PEPS effect mechanism [2]. This work was supported by The Ministry of Sci-ence and Higher Education (grant № 1609/B/H03/2009/36). M.O. thanks The Foundation for Polish Science for the MPD Programme fellowship co-financed by the EU European Regional Development Fund. [1] W. J. Middleton, E.L. Little, D.D. Coffman, V.A. Engelhardt, J Am Chem Soc. 80 (1958) 2795–806. [2] A.K. Podborska, M.F. Oszajca, S.A. Gawęda, K.T. Szaciłowski, IET Circuits Devices Syst. 5 (2011) 103-14.

NC

C-

CN

CN

CN

CN

NC

N-

CN

CN CN

CN

CN

NC

N-

CN

CN

N-

CN

CN

CN

NC

NC

CN

CN

CdSe

PO

P O

P OP

O

PO

P

O

P

OP

O

PO

POP

O

PO

P

O

P

O

Figure 1. TCNE and its derivatives modify-ing the CdSe surface

Oral Communications


Fig.1 The PEPS effect in TCNQ@TiO2 material.

New optoelectronic logic devices based on surface-m odified TiO 2

Podborska A.1, Szaciłowski K. 1,2

1 Faculty of Chemistry, Jagiellonian University, [email protected]

2 Faculty of Non-Ferrous Metals, AGH University of Science and Technology

Nowadays people require more and more powerful computing devices. Classical electronic devices are, however, insufficient. One of the feasible solutions to this problem seems to be

application of molecular switching devices. Furthermore, the application of light as the informa-tion carrier may further improve the performance of molecular-scale devices. The most interest-ing materials, in point of view of optoelectronics, are hybrid materials showed photoelectro-chemical photo-current switching (PEPS) effect. This effect can be defined as switching of photocurrent polarity on change in photoelectrode potential and/or incident light wavelength. This effect was observed in some surface-modified TiO2 materials [1-4].

Combination of 7,7',8,8'-tetracyanoquinodimethane (TCNQ) which is a good one-electron acceptor and titanium dioxide (TiO2) - a very good semiconductor results a new hybrid material with unique properties. Photoelectrodes prepared from this hybrid material exhibit the PEPS effect. Changing the wavelength or the photoelectrode potential easily switches the direction of photocurrent. At positive polarization of the photoelectrode only anodic photocurrent are ob-served as it can be expected for n-type semiconductor. At more negative potentials only ca-thodic photocurrent are observed.

Photoelectrochemical and spectroscopic studies allowed the elucidation of the mechanism of photocurrent switching. This mechanism is based on photoinduced electron transfer proc-esses from TCNQ molecule to TiO2 particle. Geometry and electronic structure calculations using DFT method confirmed this mechanism.

Photoelectrochemical properties of TCNQ@TiO2 materials seems to be suitable to construct the simple logic gates or more advances logic devices, such as demultiplexer [5-7].

[1] S. Gawęda, G. Stochel, K. Szaciłowski, Chem. Asian J. 2, 580-590 (2007) [2] K. Szaciłowski, W. Macyk, M. Hebda, G. Stochel, ChemPhysChem, 7, 2384-2391 (2006) [3] K. Szaciłowski, W. Macyk, W. Chimia, 61, 831-834 (2007) [4] S. Gawęda, G. Stochel, K. Szaciłowski, J. Phys. Chem. C, 112, 19131–19141 (2008) [5] A. Podborska, K. Szaciłowski, Austr. J. Chem. 63, 165-168 (2010) [6] J. Mech, R. Kowalik, P. Kwolek, A. Podborska, K. Szaciłowski, Austr. J. Chem. 63, 1330-1333 (2010) [7] S. Gawęda, R. Kowalik, P. Kwolek, W. Macyk, J. Mech, M. Oszajca, A. Podborska, K. Szaciłowski

Isr. J. Chem., 51, 36–55 (2011)

Oral Communications


The synthesis and optical properties of novel couma rins

Tasior M.1, Gryko D. T.1

1 Institute of Organic Chemistry, Polish Academy of Sciences, [email protected]

One of the major objectives in the field of artificial photosynthesis is to create synthetic com-

plexes that are able to convert and store light energy [1]. Numerous artificial photonic assem-blies based on porphyrin architectures have been designed with the goal of achieving efficient energy and charge transfer. Corroles, one carbon short analogues of porphyrins, have recently emerged as an independent area of research. Their coordination chemistry, synthesis, chemical transformations, electrochemistry and other properties have been studied in great detail [2]. In contrast to porphyrins, the photophysics of corroles has scarcely been studied [3].

As a part of broader program in the chemistry of corrole containing assemblies, we have created covalently linked corrole-coumarin dyads. Coumarins were chosen because of their excellent and well documented photochemical and photophysical behavior. Herein, we report the results of our synthetic and photophysical studies.

HN

N

NH

NH

FF

FF

O

O

O

O

O

NEt2

C6F5

C6F5

[1] D. Gust, T. A. Moore, A. L. Moore, Acc. Chem. Res. 34, 40 (2001). [2] D. T. Gryko, M. Tasior, B. J. Koszarna, J. Porphyrins Phthalocyanines. 7, 239 (2003). [3] F. D’Souza, R. Chitta, K. Ohkubo, M. Tasior, N. K. Subbaiyan, M. E. Zandler, M. K. Rogacki, D. T. Gryko, S. Fukuzumi, J. Am. Chem. Soc. 130, 14263 (2008).

Acknowledgment: Financial support of our work from the Foundation for Polish Science (Grant number TEAM/2009-4/3) is gratefully acknowledged.

Oral Communications


Figure 1 . Subporphyrins

Radiationless Deactivation of Subpyriporphyrins

Pawlicki, M.1, Myśliborski, R.1, Latos-GraŜyński, L.1

Kim, K.-S.,2 Lim, J.-M.,2 Kim, D,2

1 Department of Chemistry, University of Wroclaw, [email protected] 2 Department of Chemistry, Yonsei University

Boron(III) subporphyrins i.e. 1, present features characteristic for aromatic macrocycles, with typical spectroscopic properties and rather high S1 → S0 emission.[1] In contrast to the proper-ties of 1, subpyriporphyrin 2,[2] a very first subporphyrin (a homologue of [14]triphyrin) without a centre boron(III), does not present such behaviour. It’s character remains non-aromatic as the presence of pyridine blocks the delocalization. The absence of boron(III) in the centre leaves the inside proton giving a unique donors set with three, ‘unblocked’ nitrogens observed for smaller macrocycles. These free nitrogens makes possible a systematic exploration of the pro-

tonation and its influence on the spectroscopic behaviour.[3] In contrast to 1, the absence of boron(III) in 2 creates an opportunity for observation of spectroscopic properties for subporphy-rin skeleton where NH tautomerization within the coordination cavity is possible. The results of such studies will be presented and discussed.

[1] Y. Inokuma, Z.-S. Yoon, D. Kim, A. Osuka J. Am. Chem. Soc. 129, 4747 (2007) [2] R. Myśliborski, L. Latos-GraŜyński, L. Szterenberg, T. Lis Angew. Chem. Int. Ed. 45, 3670 (2006) [3] K.-S. Kim, J.-M. Lim, R. Myśliborski, M. Pawlicki, L. Latos-GraŜyński, D. Kim J. Phys. Chem. Lett. 2, 477 (2011)

Oral Communications


Photon-induced and spontaneous transformations of t he structure

of cytosine molecule

M. J. Nowak 1, L. Lapinski 1, I. Reva 2 and R. Fausto 2

1 Institute of Physics, Polish Academy of Sciences, Warsaw, Poland, [email protected] 2 Department of Chemistry, University of Coimbra, Coimbra, Portugal

Excitation of cytosine isolated in an Ar matrix with narrowband UV radiation promotes

selective transformations into its rare tautomers. Laser light UV, λ=314 - 312 nm, irradiation of the low-temperature matrix containing cytosine monomers resulted in syn-anti photo-isomerization between the two imino-oxo forms (IO1↔IO2), whereas the substantially more populated amino-hydroxy (AH) and amino-oxo (AO) forms stayed intact. Subsequent irradiation with shorter-wavelength UV, λ=311 nm, laser light led to two concomitant phototautomeric processes consuming the amino-oxo isomer: (i) oxo→hydroxy hydrogen-atom transfer convert-ing the amino-oxo form into the amino-hydroxy tautomer, AO → AH; (ii) amino→imino hydro-gen-atom transfer converting the amino-oxo form into the imino-oxo isomers AO → IO [1].

N

N

NHH

O

H

N

N

NHH

OH

N

N

NHH

O

H

N

N

NH

O

H

HN

N

NH

O

H

H

AH1 AH2 AO IO1 IO2

7013 cm-1

7034 cm-1

NIR / IR

tunneling

λ > 314 nmλ > 311 nm λ > 311 nm

Fig. 1. Hydrogen-atom-transfer processes leading to transformation between the isomeric forms of cyto-

sine.

Narrow band near-IR laser light was used to excite one of the conformers of amino-hydroxy tautomer of cytosine to the vibrational state corresponding to the overtone of the OH stretching vibration. Such excitation promoted torsion of the OH group and led to the change of conforma-tional form of the hydroxy tautomer. For cytosine monomers, NIR laser irradiation at 7013 cm-1 led to AH1 → AH2 transformation while irradiation at 7034 cm-1 induced reverse transformation AH2 → AH1 of the two conformers [2]. It was demonstrated that other forms of cytosine (amino-oxo and imino-oxo) are not affected by NIR irradiation.

Upon broadband irradiation with the beam from the IR source of FTIR spectrometer the population ratio of the two amino-hydroxy conformers changed towards a ratio corresponding to the photostationary state. Evolution of conformer population ratio towards the photostationary ratio occurred independent of the initial ratio of conformers, which could be prepared by a narowband-NIR-induced population shift in favor of one of the forms [3].

Moreover, spontaneous tunneling conversion of the higher-energy conformer AH2 into a lower-energy form AH1 was observed for cytosine isolated in a low-temperature argon matrix kept in the dark. This process was slow and occurred in a time scale of days [3].

[1] L. Lapinski, I. Reva, M. J. Nowak and R. Fausto, Phys. Chem. Chem. Phys. 13, 9676 (2011). [2] L. Lapinski, M. J. Nowak, I. Reva, H. Rostkowska and R. Fausto, Phys. Chem. Chem. Phys. 12, 9615 (2010). [3] I. Reva, M. J. Nowak, L. Lapinski, and R. Fausto, Phys. Chem. Chem. Phys. submitted (2011).

Oral Communications


Electron transfer and photodissociation in a spiroc yclic

bichromophoric molecule

Karolak-Solarska E.,1 Kijak M.,1 Fita P.,2 Nowacki, J.,3 Karpiuk J.1

1 Institute of Physical Chemistry, Polish Academy of Sciences; [email protected] 2 Faculty of Physics, University of Warsaw

3 Faculty of Chemistry, University of Warsaw

The linkage of two cyclic systems by a central tetrahedral carbon atom (sp3) results in for-mation of spiro compounds. In spite of the mutually perpendicular orientation of the two π-electronic systems, both subunits can interact via through-space 3-D spiroconjugation under the

condition that the MOs of both fragments are antisymmetric with respect to the two perpendicular bisecting planes.

In CVLB, a spirocyclic ana-logue of crystal violet lactone (CVL), the spiroconjugation mani-fests itself by non-additivity of electronic absorption spectra of

the structural subunits. Quantum chemical modeling confirms the presence of spiroconjugation between antisymmetric HOMOs localized on the two halves of CVLB, resulting in formation of new orbitals spanning over the entire molecule and leading to new electronic transitions.

The two perpendicularly oriented subunits of CVLB, 6-dimethylaminophtalide (6-DMAPd) and bis-N,N-dimethylaminofluorene (bDMAF), when considered as independent molecules, are highly efficient fluorophores with comparable energies of their S1 states. In contrast to CVL displaying in non-polar solvents efficient fluorescence from the S1 state localized on 6-DMAPd [1, 2], rigid CVLB undergoes very fast radiationless deactivation [3]. The aim of our work was to elucidate the impact of structurally induced spiroconjugation on CVLB photophysics and the role of excited state energetics in the enhanced excited state nonradiative deactivation.

Transient absorption measurements in the low ps domain reveal rapid relaxation to the fluo-rescent CT state (as in CVL) and formation of a dark state that is tentatively assigned to a ring-open form (Z) of CVLB. At present we can not determine if the Z form is populated diabatically or adiabatically – similarly as in rhodamine lactones [4]. The decays of the CT state and of the dark state are not kinetically correlated, indicating that branching into the two deactivation path-ways occurs only before the vibronic relaxation of the primarily excited FC state is completed.

[1] J. Karpiuk, J. Phys. Chem. A 108, 11191 (2004) [2] U. Schmidhammer, U. Megerle, S. Lochbrunner, E. Riedle, J. Karpiuk, J. Phys. Chem. A 112, 8487 (2008) [3] J. Karpiuk, E. Karolak-Solarska, J. Nowacki, Phys. Chem. Chem. Phys. 12, 8804 (2010) [4] J. Karpiuk, Z. R. Grabowski, F. C. De Schryver, J. Phys. Chem. 98, 3247 (1994)

(H3C)2N

O

O

N(CH3)2

(H3C)2N

O

O(H3C)2N

N(CH3)2(H3C)2N

CVL CVLB

Oral Communications


0

5000

10000

15000

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ener

gy [c

m-1

]

S1FC(4.58 D)

S1(4.74 D)

S0FC(2.72 D)

S0(3.04 D)

2723

1 cm

-1

2308

7 cm

-1

2211 cm-1

1933 cm-1

µµµµ(S0)

µµµµ(S1)

Excited state deactivation processes in 3-aminoflavone

A. Szemik-Hojniak1, I. Deperasinska2, Ł. Wiśniewski1

1Faculty of Chemistry, University of Wroclaw, Joliot-Curie 14 st; 50-383 Wroclaw (Poland).

E-mail: [email protected] 2Institute of Physics, Pol. Acad. of Sciences, Al.Lotników 32/46, 02-668 Warsaw (Poland).

Flavones, are the sub group of flavonoids – widely distributed group of naturally occurring biologically active compounds, demonstrating antibacterial, anticancer, cytostatic and other important therapeutic properties [1,2].

In the excited state they show a complex photophysical characteristics like the excited state intramolecular proton (ESIPT) or electron transfer processes found in 7- , 5- or 3-hydroxyflavones [3]. In either of them the role of the solvent polarity is highlighted. In studied here 3-aminoflavone (3-AF, Figure 1), the N-H…O hydrogen bonding geometry is unfavorable for the ESIPT to occur and the S0 → S1

FC (ππ*) transition demonstrates a partial CT nature.

Fig.1.Molecular structure and energetics of 3AF molecule.

The transfer of charge occurs between the 62 π HOMO orbital of the amino group and 63 π* LUMO orbital of the chromon ring. Its dipolar changes result in batochromically shifting emission maxima with the solvent polarity increase (Stokes shift value in THF is 6489 cm-1). Interesting experimental observations combined with TD DFT calculations revealed that in apolar and weakly polar solvents the excited state deactivation of 3AF proceeds through the radiative fluorescence and nonradiative intersystem crossing (ISC) paths while in the polar media, the internal conversion (IC) turns out to be the dominant process.

This work was supported by the following grants: Min. of Sci. and High Educ.(Poland) Nr N N204 131338; ICMCM-Warsaw (G32-10) and WCSS-Wroclaw (G-61).

[1] B.Hallivel. et al., J. Am. J. Clin. Nutr. 81 (2005) 268S [2] B.Kośmider, R., Osiecka, Drug. Dev. Res. 63 (2004) 200 [3] P.K. Sengupta, M. Kasha, Chem. Phys. Lett. 68 (1979) 382.

Oral Communications


Investigation of the bi-molecular energy transfer p rocesses

in liquid solutions

Jędrzej Solarski 1, Gonzalo Angulo 1, Andrzej Kapturkiewicz 1,2

1 Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 War-saw, Poland, [email protected]. 2 Institute of Chemistry, Faculty of Sciences, University of Siedlce,3 Maja 54, 08-110 Siedlce, Poland

Energy transfer reactions are one of the important photoinduced processes to due their crucial role in the early stages of photosynthesis and potential technological applications. Despite that the general understanding of such phenomenon in liquid media is still lacking [1, 2]. It is espe-cially true for a proper kinetic description in terms of reactants and medium properties. This arises from the scarcity of experimental data due to the specific requirements needed to be fulfilled by the studied physico-chemical model systems in order to reveal the relevant kinetic information with enough large precision.

By investigating energy transfer processes between excited triplet states of luminescent iridium complexes and organic energy acceptors most of the common drawbacks can be overcame that allows for quantitative estimation of the kinetics parameters of the reversible energy trans-fer processes (REN) from analysis of bi-exponential decays of the donor luminescence [3]. The applied approach can be also proposed as an alternative method for determining molecular triplet state energies and lifetimes that are sometimes difficult to measure in liquid media.

[1] K. Sandros, Acta Chem. Scand., 18, 2355, (1964) [2] V. Balzani, F. Bolletta, F. Scandola, J. Am. Chem. Soc., 102, 2152, (1980) [3] J. Solarski, G. Angulo, A. Kapturkiewicz, J. Photochem. Photobiol. A Chemistry, 218, 58-63, (2011)

Oral Communications


Supersonic jet spectra and ab initio modelling of S 0→S1 transition of anthranilic acid molecule

Kolek P.1, Andrzejak M.2, Najbar J.2

1 Institute of Physics, Rzeszów University, [email protected]

2 Faculty of Chemistry, Jagiellonian University

Laser induced fluorescence (LIF) excitation spectra for the S0→S1 transition of anthranilic acid molecule as well as the spectra of the molecules deuterated in the substituent groups (COOD, ND2) was investigated. In addition to the LIF spectrum of pristine molecule[1], three spectra of partially deuterated samples were recorded, for isotopic exchange ratio ca. 25%, 50% and 80%[2] in the substituent groups (Fig.1).

The deuteration shifts of vibrational bands well correlate with the values computed with ab initio CC2 quantum mechanical method as well as time-dependent perturbation TD-DFT(B3LYP) method [3]. The intramolecular hydrogen bond is significantly stronger in the S1 state than in the ground state. Additionally, bond lengths and angles in the aromatic ring, within the substituents and between the ring and the substituents undergo significant changes and they induce the presence of strong fundamentals in the excitation spectrum.

The blue-shift of the 00 transition due to the isotopic substitution (COOD, ND2), is equal to 47 cm–1. This relatively large value is caused primarily by a significant decrease of the N–H stretching frequency associated with the increase of strength of the intramolecular hydrogen bond upon the electronic excitation. The deuteration shifts of the 00 band in the S0→S1 transi-tion can be interpreted of in terms of the zero point energies (ZPE) of the relevant electronic states. These corrections include the contribution of the ZPE for the inversion mode of the iso-topically substituted amino group (NH2, NHD, NDH and ND2), in addition to the contribution of harmonic vibrations. This fine effect was modelled using the one-dimensional double-well po-tential[2].

Fig.1 LIF spectra of anthranilic acid prtially deuterated in the substituent groups ordered according to in-creasing isotopic exchange ratio: 0% (bottom), 25%, 50%, and 80% (top). Band position with respect to the

electronic origin for pristine molecule (v -v00 NH2 COOH where v00 NH2 COOH = 28 591 cm-1) is presented.

[1] P. Kolek, S. Lesniewski, K. Pirowska, J. Najbar, J. Mol. Spectr. 249(2) (2008) 100 [2] P. Kolek, S. Leśniewski, M. Andrzejak, M. Góra, P. Cias, A. Węgrzynowicz, J. Najbar, J. Mol. Spectr. 264(2) (2010) 129 [3] S. Lesniewski, P. Kolek, K. Pirowska, A.L. Sobolewski, J. Najbar, J. Chem. Phys. 130 (2009) 054307–1

Oral Communications


Fig.1. NCI analysis for 9,10,19,20-tetramethylporphicyne (CMPC).

Electron localization function, noncovalent interac tions analysis

and other theoretical tools in photochemistry

Kasprzycki P., Fita P., Radzewicz Cz.

Institute of Experimental Physics, University of Warsaw, HoŜa 69, Poland

Numerical solutions of the Schrödinger equation can nowadays be obtained for reasonably large organic and organometallic molecules with useful accuracy using approximate ab initio or DFT methods [1]. These approximate solutions are also available for porphycene which is an

important chromophore [2]. Por-phycene and its derivatives show useful properties for material sciences and are also considered excellent photosensitive media for applications in photodynamical therapy of cancer [3, 4]. Several papers have discussed the en-ergy structure and dynamic as-pects of hydrogen transfer in this systems [5-7]. We report on the results of NCI and ELF analysis - two theoretical tools based on Bader approach [8, 9] - performed for four symmetrically substituted porphycene derivatives. We have carried out DFT and TDDFT cal-

culations at the level of B3LYP/6-311(d,p). These calculations were followed by NCI and topo-logical ELF analysis. Calculations showed the correlation between value of reduced density gradient and time of proton transfer in the examined systems. We show that noncovalent inter-actions analysis is useful not only for detection of strong hydrogen bounds and weak van der Waals interaction but also for comparing power of hydrogen bounds in the four investigated compounds. This can be significant for understanding the mechanism of double hydrogen trans-fer between inner nitrogen atoms.

[1] P. Hohenberg, W. Kohn, Phys. Rev. B 1964, 136, 864 - 871; [2] D. Sanchez-Garcia, J. L. Sessler, Chem. Soc. ReV. 2008, 37, 215. [3] Denisov, I. G.; Makris, T. M.; Sligar, S. G.; Schlichting, I. Chem Rev 2005, 105, 2253; [4] J. C. Stockert, M. Canete, A. Juarranz, A. Villanueva, R. W. Horobin, J. I. Borrell, J. Teixido, S. Nonell, Curr. Med. Chem. 2007, 14,997;

[5] Ł. Walewski, J. Waluk, B. Lesyng, J. Phys. Chem. A, 2010, 114, 2313–2318; [6]M. Gil, J. Waluk J. Am. Chem. Soc. Vol. 129, No. 5. 2007; [7] A. D. Quartarolo, S. G. Chiodo, N. Russo, J. Chem. Theory Comput., 6(10), 3176-3189;

[8] E. R. Johnson, S. Keinan, , J. Contreras-García, R. Chaudret, J-P Piquemal, D. Beratant, W. Yang, J. Chem. Theo. and Comp., 2011, 25;

[9] A. D. Becke, K. E. Edgecombe, J. Chem. Phys. 1990, 92, 5397;

Oral Communications


Substituent effect on the energetical landscape of the molecular

photo-switch

Rode M. F.1 and Sobolewski A. L.1

1 Institute of Physics, Polish Academy of Sciences, [email protected]

Molecular switches enable the storage of information on a molecular level, and their application in nanotechnology, biomedicine, and computer chip design. The molecular system which may serve as a molecular switch must posses two stable forms which may be switched by an electric filed, chemical reaction or optical excitation.

Fig. 1. Photophysical scheme of the molecular photo-switch

In our investigation we are search-ing for molecular photo-switches which operate on the Excited State Intramolecular Proton Transfer (ESIPT) [1,2,3,4]. The switching proc-ess involves the long-range transfer of a proton which is picked up by a „molecular crane” (C) at the donor site due to optical excitation, and deliv-ered to the acceptor site of the sys-tem by rotation of the crane. The reversibility of the switch is guaran-teed by the ESIPT mechanism condi-tions, which are: (i) photochromism of the system and (ii) a barrierless ac-cess on the potential-energy surface (PES) of the S1 state to the S1-S0

conical intersection (CI) which is common for both photochromic forms.

In our theoretical study we have chosen two systems: 7-hydroxy-quinoline (7HQ) and 3-hydroxy-picolinic acid (3HPA) as the molecular frames of the switch, as they may posses two isomeric forms due the presence of two distinguishing hydrogen-donor/acceptor centers: O and N atoms, being able to donate the hydrogen atom to the crane [3]. We have investigated several potential crane molecules such as carbaldehyde, pyridine, oxazine and oxime being attached at the position 8’ of the 7HQ frame, as well as a carboxylic group present in the picolinic acid, and searched for appropriate side groups (R) which, substi-tuted at the given position, would improve the energetical landscape of the molecular system [4], see Fig. 1. Our study shows how the substituent effect exerts the influence on the energetical landscape of the excited state and may be used in practice to search for materials of desired energetical and optical properties. [1] A. L. Sobolewski, Phys. Chem. Chem. Phys., 10, 1243 (2008). [2] C. Benesch, M. F. Rode, M. Cizek, R. Hartle, O. Rubio-Pons, M. Thoss, and A. L. Sobolewski, J. Phys.

Chem. C, 113, 10315 (2009). [3] L. Lapinski, M. J. Nowak, J. Nowacki, M. F. Rode, and A. L. Sobolewski, Chem. Phys. Chem., 10, 2290

(2009). [4] M. F. Rode, A. L. Sobolewski, J. Phys. Chem. A, 114, 11879 (2010).

Posters


Posters

Posters


Fig.1 The MP2/6-311++G(d,p) equilibrium structure of Na2N3NO2 and the first –order hyperpolarizability

Superalkalies forming stable molecules with electro n acceptors

Anusiewicz I.1, Freza S.2

1 Department of Chemistry, University of Gdańsk, [email protected] 2 Department of Chemistry, University of Gdańsk, [email protected]

The Na2X superalkali molecules (X=SH, SCH3, OCH3, CN, and N3) were found to be capa-

ble of forming stable [Na2X]+[Y]– salts with the species exhibiting various electron affinities (Y=MgCl3, Cl, NO2). The dipole moments, polarizabilities and first-order hyperpolarizabilities of the Na2XY ionic salts were calculated and discussed. It was found that the Na2XNO2 molecules possess the extraordinary large values of anisotropy of polarizabilities (in the 15.5-28.2×10-24 esu range) and the first-order hyperpolarizbilities (spanning the 597.8-1295.7×10-30 esu range).

Posters


Photodegradation of reactive azo dyes by advenced o xidation

processes

Brzeska M.1, Perkowski J.1, Blus K.2, Szadkowska-Nicze M.1

1Institute of Applied Radiation Chemistry, Technical University of Łódź, ,

ul.Wróblewskiego 15, 93-590 Łódź, Poland, 2Institute of Polymer & Dye Technology, Technical University of Łódź,

ul. Stefanowskiego 12/16, 90-924 Łódź, Poland e-mail: [email protected]

Reactive azo dyes represent the dominant class of synthetic colorants employed in textile industry. They are produced in large amounts and released to the environment during dyeing process. Although, wastewater released by textile industries contains azo type reactive dyes at low concentration, they are resistant to biological degradation. Advanced Oxidation Processes (AOPs) are efficient novel methods useful to accelerate the non-selective oxidation and thus the destruction of a wide range of organic substances resistant to conventional technologies. In AOPs, generally reactive, strongly oxidizing •OH radicals play the main role in destruction of the dye molecules.

The aim of our work was to study the possibility of using AOPs to decolorize of reactive dyes in aqueous solutions. We investigated photooxidation in air, (UV/air), in oxygen, (UV/O2), and ozone, (UV/O3), atmosphere, combined methods with ozone and hydrogen peroxide (UV/O2/H2O2, UV/O3/H2O2) and photo-Fenton (UV/H2O2/Fe2+) process for four reactive azo dyes (Yellow BK-221, Red BK-230, Violet BK-253 and Black RB5). Low-pressure Hg lamp (15W) was used as a source of UV light. Decolorization of dyes solutions (100 and 200 mg L-1) was ob-served spectrophotometrically by Perkin Elmer Lamda 750 spectrophotometer in UV-VIS range 190-800 nm. Progress of the photo-Fenton reaction was observed by means of chemical oxy-gen demand (COD) analysis.

It was found that decolorization of reactive azo dyes in aquoeous solutions depend on struc-ture of dye molecule, solution concentration and AOPs version. The dyes solutions were easily decolorized in O3 atmosphere, (UV/O3), (UV/O3/H2O2), and the lowest decolorization was ob-served in air. The decolorization rate of Black RB 5 solutions in all AOPs versions was similar. Decolorization degree of this dye was in range 92-98% for UV/air and UV/O3, respectively. The greatest differences in decolorization degree were observed in the case Red BK-230: 47% and 98% for UV/air and UV/O3, respectively. The photo-Fenton oxidation was poor for all dyes: . reduction of COD was lower than 22%.

Posters


Spectral and photophysical properties of individua formed by selected photochromic Schiff bases in the ground an d excited

states.

Filipczak K., Maciejewski A.

Faculty of Chemistry, Adam Mickiewicz University, Poznań [email protected]

Schiff bases have been intensely studied because of the occurrence of excited state in-tramolecular proton transfer process (ESIPT, of great importance in nature) their photochromic properties and numerous applications. Their structure implies that at a few sites the distribution of electron density and geometry of the molecule can change as a result of excitation. Schiff bases can occur in the form of enol and keto tautomers, each of them can occur as two syn-anti or cis-trans isomers, and each of them can form a few conformers (rotamers). Schiff bases can form dimer even at very low concentrations (~10-5 mol/dm3) and greater aggregates [1]. The hitherto studies of these compounds have been performed by steady state and time-resolved absorption and emission spectrometers [2]. In such conditions the absorbance meas-ured is a sum of absorptions of all individua present in a sample, similarly as the emission, so it was impossible to reliably identify these individua. As the compound studied was used at very low concentrations (10-4 – 10-5 mol/dm3) it was assumed that the sample contains exclusively single molecules of Schiff bases. Presented results were obtained by using HPLC-Abs-Em system consisting of UPLC® (or HPLC) apparatus directly coupled with a photodiode spectrophotometer (acting also as an absorption detector) and a highly sensitive spectrofluorometer (acting also as an emission detector). The use of HPLC-Abs-Em method, after adjustment of the measuring parameters, permits isola-tion of all individua present in the sample and their separation from impurities. If complete sepa-ration is not possible, this method enables the choice of the optimum parameters for measure-ments by conventional methods (e.g. λwzb, λem for measurements of emission or emission exci-tation spectra). At these optimum conditions, the influence of impurities can be eliminated or substantially limited and control. Thus it is possible to examine what are the spectral and photo-physical properties of individua formed by aromatic photochromic Schiff bases. [1] R.S. Becker, Ch. Lenoble, A. Zein J. Phys. Chem. 91 (1987) 3517 [2] M. Ziolek, G. Burdzinski, K. Filipczak, J. Karolczak, and A. Maciejewski, Phys. Chem. Chem. Phys. 10 (2008) 1304

Posters


PR PC TAA

SERS studies of porphycene

Sylwester Gawinkowski1, Jacek Waluk1

1 Institute of Physical Chemistry, Polish Academy of Sciences, [email protected]

Rapid development of Surface-Enhanced Raman Spectroscopy (SERS) techniques is stimu-lated by prospects of applications in such fields as ultrasensitive detection, down to the single molecule limit, biomedical diagnostics, or molecular imaging. Understanding the mechanisms of SERS requires experiments in which the parameters relevant for the enhancement are varied in a systematic way. For instance, different surface materials/morphologies can be tried for the same chromophore, or, vice versa, a series of appropriately modified molecules can be studied for the same support.

Porphyrin (PR) and its two structural isomers, porphycene (PC) and tetraazaannulene (TAA) were selected as probes. These molecules are similar in the geometry of the inner cavity, but significantly differ in spectroscopic properties. The investigations of both porphyrin, wellknown as a “pigment of life”, and porphycene isomers, already shown to be very promising candidates for phototherapeutic agents, are a subject of much study due to the importance for fundamental research. The choice was justified by the fact that these molecules have been characterized by methods of vibrational and electronic spectroscopy in our group [1,2]. These compounds are not toxic, thus their single molecule applications in biology and medicine seem to be promising in the future. In this communication, we report on the SERS spectra of PC. The strategy is to monitor possi-ble changes in the spectral positions and relative intensities in the SERS spectra, caused by the proximity of active metal surface. In particular, we focus on the symmetry of the probed modes, with the goal of analysing the relationship between the orientation of the probed chromophore and its orientation with respect to the active surface.

[1] Gawinkowski, S; Eilmes, J; Waluk, J., J. Mol. Struct., 976, 215 (2010) [2] Gawinkowski, S; Walewski, Ł; Vdovin, A; Slenczka, A; Ford, S; Johnson, M; Lesyng, B; Waluk, J; in preparation

This work was supported by the European Union within European Regional Development Fund, through grant Innovative Economy (POIG.01.01.02-00-008/08).

Posters


Spectral and photophysical properties of

(E)-N-(alkyl-carbonyl-alhoxy)-2’(4’)-hydroxy-4-stil bazolium halides.

Gierszewski M., Prukała D., Sikorski M.1 1 A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań E–Mail: [email protected]

(E)-2’(4’)-hydroxy-4-stilbazolium halides are composed by a donor group (hydroxy group)

and an acceptor group (substituted pyridinum moiety), connected by an ethylene bridge, pos-sessing an extended conjugated π-electronic system [1]. N-substituted derivatives of (E)-azastilbenols – quaternary stilbazolium salts, belonging to the hemicyanine class of compounds, have a wide range of applications. Quaternary stilbazolium salts show a very strong antimicro-bial acitivity, therefore they may be used as cosmetic preservatives. Indeed, we have previously found that derivatives of (E)-azastilbenols are active against various species of fungi, including corilus varsicolor, Gleophyllum trabeum, Paria placeuta etc. [2-3]. Stilbazolium dyes can also be used as photosensitizers in photodynamic and photodiagnosis therapy (PDT and PDD) [4-5], liquid crystals in non-linear optics [6], sensitizers in colour photography [7] and fluorescence probes for monitoring free radical polymerization processes [8].

Spectrophotometric analysis

Stilbazolium dyes display negative solvatochromism, because the ground state is more sta-bilized by polar solvents than the excited state and their dipole moment is smaller in the excited state than in the ground state.

Spectrofluorimetric analysis

Spectrofluorimetric analysis (emission, excitation specta; quantum yield; Stokes shifts) shows, that the excited state of quaternary stilbazolium salts decay by non-radiative processes in protic solvents.

Protonation / deprotonation equilibrium

We found that the protonated form of studied quaternary stilbazolium salts showed one band, with the absorption maximum dependent on pH. The protonated form at acid pH had the absorption maximum at ca. 375nm for compound 1 and at ca. 400nm for compound 2. The respective deprotonated forms absorbed at 450 and 480 nm.

References

[1] D.Prukala, W.Prukala, I.Khmelinskii, M.Sikorski, Physical Chemistry Chemical Physics 13 (2011) 6950-6960. [2] E.Wyrzykiewicz, A.Blaszczyk, B.Kedzia, Farmaco 55 (2000) 151-157. [3] E.Wyrzykiewicz, A.Lapucha, K.Golankiewicz, S.Kucharski, J.Krysinski, Pharmazie 36 (1981) 407-410. [4] D.Frackowiak, A.Waszkowiak, H.Maikowski, R.M.Ion, J.Cofta, K.Wiktorowicz, Acta Biochimica Polonica 48 (2001) 257-269. [5] E.Staskowiak, A.Dudkowiak, I.Hanyz, K.Wiktorowicz, D.Frackowiak, Journal of Photochemistry and Photobiology A-Chemistry 163 (2004) 127-134. [6] C.Bosshard, F.Pan, M.S.Wong, S.Manetta, R.Spreiter, C.Z.Cai, P.Gunter, V.Gramlich, Chemical Physics 245 (1999) 377-394. [7] L.G.S.Brooker, F.L.White, R.H.Sprague, Journal of the American Chemical Society 73 (1951) 1087-1093. [8] J.Paczkowski, D.C.Neckers, J Polymer Science Part A 31 (1993) 841-846

Posters


2-Chlorophenol photooxidation using meso -tetraphenylporphyrin

immobilized into polyurethane nanofabrics

Gmurek M.1, Mosinger J.2,3, Miller J.S.1

1Faculty of Process and Environmental Engineering, Technical University of Lodz, e-mail: [email protected]

2Faculty of Science, Charles University in Prague, 3Institute of Inorganic Chemistry, v.v.i., Academy of Sciences of the Czech Republic,

The photodegradation of the 2-chlorophenol (2-CP), belonging to the family of endocrine

disrupting compounds was studied. The reaction was performed in the aerated aqueous solutions using meso-tetraphenylporphyrin (TPP) as a sensitizer. Porphyrins are efficient sensitizers for singlet oxygen generation and play an important role in the photodynamic therapy, synthesis of fine chemicals and photodegradation of water pollutants. The use of immobilized sensitizers has several advantages, among other the problems of sensitizer separation from the reaction mixture can be avoided and the reusability of the photosensitizer can be realized. The literature on this topic is rather scarce and research are focused mainly on water-soluble porphyrins or metalloporphyrins [1]. In this study polymeric polyurethane nanofabrics prepared by the electrospinning method were used as a carrier for the studied sensitizer.

The reactions were conducted in semicontinuous system using xenon arc lamp simulating solar radiation. The influence of various parameters on the reaction course were investigated, such as: 2-CP and oxygen concentration, pH of the reaction solution and the multiple-use-stability of the immobilized sensitizer. The participation of molecular singlet oxygen in the photooxidations was confirmed using indirect methods using sodium azide as a physical quencher and imidazole as a chemical quencher of 1O2. The collected data of this heterogeneous process allowed us to describe it using Langmuir – Hinshelwood model [2] and to determine the kinetic parameters.

[1] M. Trytek, J. Fiedurek, A. Lipke, S. Radzki Journal of Sol-Gel Science and Technology 51, 272-286, (2009) [2] Z. Xiong, Xu Y, Zhu L, Zhao J. Environ Sci Technol. 15 39(2):651-7 (2005)

Posters


Polymorphism in 1 H-Pyrrolo[3,2- h]quinoline: experimental and

theoretical study

A. Gorski, S. Gawinkowski, J. Waluk


Heteroazaaromatic compounds exhibiting both hydrogen-bonding donor and hydrogen-bonding acceptor properties are often investigated by a wide range of theoretical and spectro-scopic methods. 1H-Pyrrolo[3,2-h]quinoline (PQ) composed of pyrrole, indole, and quinoline moieties becomes an object of intensive study due to a new-discovered in last decade phe-nomenon of solvent-catalyzed excited-state tautomerization [1]. The direct intermolecular proton transfer in similar compounds is unfavorable, because of spatial separation of donor and accep-tor groups. Nevertheless, in H-bonded solute–solvent complexes in protic solvents, solvent-assisted excited state proton transfer becomes possible. The photophysical and spectroscopic properties of the phototautomers differ significantly from those of a “normal” species [1], which opens perspectives to apply mentioned group of compounds as a fluorescence probe of water or alcohol content in medical and biological applications [2]. In spite of many studies, the vibra-tional assignment of PQ monomer in the ground state, as well as accurate crystal structure of PQ dimer are still unknown.

Vibrational assignments of PQ monomer and dimer in the ground state were carried out in our group based on IR measurements in rare gas matrices at low temperature, as well as IR and Raman experiments in solutions at room temperature, in combination with quantum chemi-cal density functional theory (DFT) calculations.

Two polymorph crystal forms of PQ dimer, monoclinic and triclinic were postulated. The re-sults obtained by X-ray spectroscopy are in good agreement with theoretical calculations based on DFT and generalized gradient approximations implemented in the CASTEP (Cambridge Serial Total Energy Package) [3].

[1] Waluk J., Hydrogen-bonding-induced phenomena in bifunctional heteroazaaromatics, Acc. Chem. Res. 36, 832-838 (2003) [2] Kyrychenko A. V., Waluk J., Distribution and favorable binding sites of pyrroloquinoline and its analogues in a lipid bilayer studied by molecular dynamics simulations, Biophysical Chemistry, 136, 128-135 (2008) [3] Segall M. D., et al., First-principles simulation: ideas, illustrations and the CASTEP code, Journal of Physics-Condensed Matter, 14, 2717-2744 (2002)

Posters


Spectroscopic properties of individua formed by imi dazolium ionic

liquids with chloride and tetrafluoroborate anions

Gutowska N.1, Kiszko M.1, Kubicki J.3, Maciejewski A.1,2

1Photochemistry and Spectroscopy Laboratory, Faculty of Chemistry, Adam Mickiewicz University, Poznań

2Center for Ultrafast Laser Spectroscopy, Adam Mickiewicz University, Poznań 3Quantum Electronics Department, Faculty of Physics, Adam Mickiewicz University, Poznań

e-mail: [email protected]

Ionic liquids make a class of compounds consisting of organic cations such as alkylimida-zolium, alkylpyridinium or tetraalkylammonium combined with a variety of organic or inorganic anions. Recently, they have been intensively studied because of their unique physicochemical structure-dependent properties, such as low vapour pressure, low melting point, high thermal stability, miscibility with water or hydrophobic solvents etc. [1-3].

Imidazolium ring of ionic liquid cation can be potentially engaged in π-π interaction with another cation’s ring. Self-association phenomena are well known for many compounds, including imidazole and it’s methyl derivatives [4]. Unfortunately, the knowledge of aggregates formed by ionic liquids is still insufficient. A few authors have claimed that ionic liquids can exist as single ion pair surrounded by solvent molecules or as aggregates [5]. It is also shown that absorption spectra of the same neat ionic liquid measured at different laboratories are different due to presence of impurities [6]. That is why it is so difficult to determine spectro-scopic properties of ionic liquids and individua which they form.

Using high-performance liquid chromatography (HPLC) combined with a spectrophotometer with photodiode array detector (PDA) it is possible to measure absorption spectra at any time while analysis is being performed. Concentration of the samples used makes a significant im-pact on results. The influence of impurities on absorption is negligibly small if ionic liquids are used in low concentrations. Four imidazolium ionic liquids (in a broad concentration range) were investigated under varied chromatographic conditions (column type, mobile phase compo-sition, flow rate, injection volume). The results of this work indicate that ionic liquids can form several individua characterised by different absorption spectra. Their presence and concentrations depend on the concentration of ionic liquid and water content in the mobile phase (solvent).

[1] T. Welton, P. Wasserscheid, Ionic liquids in synthesis (Wiley-VCH, 2008) [2] J. Phys. Chem. B, Vol. 111 No. 18 (2007) [3] N. V. Plechkova, K. R. Seddon, Chem. Soc. Rev. 37, 123 (2008) [4] F. Peral, E. Gallego, Journal of molecular structure, 415, 187 (1997) [5] B. Kirchner, Ionic Liquids (Springer Verlag, 2009) [6] R. Katoh, Chem. Lett. 36, 1256 (2007) and references therein

Posters


Analysis of the high excited B 1Σ+ Rydberg state in the rare 13C17O

isotopic molecule

Hakalla R., Zachwieja M., Szajna W., Kolek P., Ostrowska-Kopeć M., Piotrowska I., Kępa R.

Atomic and Molecular Physics Laboratory, Institute of Physics, Rzeszów University,

[email protected]

So far unobserved in the very rare 13C17O isotopic molecule the B1Σ+ state was obtained on the basis of Ångström system (B1Σ+-A1Π) under high resolution as an emission spectrum using an optic conventional spectroscopic technique. Rotationally resolved spectra of 0-2 vibrational band is shown in Fig.1 as an example.

The light source was the hollow-cathode lamp with two anodes built in our laboratory, with previously deposited small quantity of 13C carbon on the electrodes and filled with isotopic oxy-gen 17O2. The emission from the discharge was observed with a plane grating spectrograph and recorded by a photomultiplier tube. The spectrum of the Ångström system in the range 19300-21200 cm-1 of the rare 13C17O isotopic molecule was precisely measured and rotationally ana-lyzed. It allowed to determine for the first time in this molecule the rotational constants for the B1Σ+ Rydberg state as well as for the lower A1Π state.

The existence of irregularities in the strongly perturbed A1Π state up to the observed Jmax level was investigated in detail. Numerous rotational perturbations observed in A1Π state in 13C17O molecule have been identified. The suspected candidates responsible for these irregu-larities in A1Π state were indicated by means of graph of the rovibronic levels. Simultaneously, the B1Σ+ state was turned out quite regular up to the observed Jmax level.

Fig.1 An expanded view of the 0-2 band of the B1Σ+-A1Π transition of the 13C17O. The less intensive 0-2 band of the Ångström system (B1Σ+-A1Π) system in the 13C16O molecule is treated here as the isotopic

pollution (its band head was marked with asterisk). The dotted lines indicate the tips of the relatively very strong calibration lines.

Posters


Spectroscopy of the B 1Σ+-A1Π Ångström system in the optical

range 19200-21100 cm -1 for the 13C16O isotopic molecule

Hakalla R., Zachwieja M., Szajna W., Kolek P., Ostrowska-Kopeć M., Piotrowska I., Kępa R.

Atomic and Molecular Physics Laboratory, Institute of Physics, Rzeszów University,

[email protected]

In the optical range of 19200-21100 cm-1 using a conventional spectroscopic technique, the emission spectrum of the Ångström system (B1Σ+-A1Π) in 13C16O isotopic molecule was re-corded. Rotationally resolved spectra of 0-1 vibrational band is shown in Fig.1 as an example. The light source was the hollow-cathode lamp with two anodes built in our laboratory, with pre-viously deposited small quantity of 13C carbon on the electrodes and filled with isotopic oxygen.

Under high resolution the emission from the discharge was observed by using a plane grat-ing spectrograph PGS-2 and recorded by a photomultiplier tube. The precision estimated to be 0.002 - 0.005 cm-1. The rotational reanalysis of the bands made it possible to extend and to improve the information for both combining states. Especially the spectroscopic and quantum-mechanical constants of the B1Σ+ Rydberg state around its v=0 level were more precise.

Numerous rotational perturbations observed in the A1Π of the 13C16O isotopic molecule were confronted with the perturbation observed earlier. Simultaneously the B1Σ+ state was turned out quite regular up to the observed Jmax level.

Fig.1 An expanded view of the 0-1 band of the B1Σ+-A1Π transition of the 13C16O. The dotted lines indicate

the tips of the relatively very strong calibration lines.

Posters


π-Expanded porphyrins - synthesis and photophysics

Dominik Koszelewski, Daniel T. Gryko

Institute of Organic Chemistry PAS, 01-224 Warsaw, Poland, Kasprzaka 44/52

Optical limiting is a nonlinear effect consisting of a decrease in the transmittance of the NLO material under high-intensity illumination. Among different functions optical limiting devices can perform, the most useful one is the protection of optical elements, sensors and human eye against damage by exposure to a sudden high-intensity light. Dipolar or quadrupolar organic molecules have been shown to be of particular interest since they allow combining very fast (femtoseconds) intrinsic 2PA with somewhat slower reversed saturable absorption (RSA) [1]. The material for optical limiting applications based on RSA has to additionally possess long-living excited triplet state [2]. Compounds possessing large σ have typically short lived triplet-state. On the other hand molecules which have long-lived triplet-state, usually have small σ. The only class of molecules which can fulfill these requirements are porphyrins [3]. Here we would like to present the synthesis and characterization of new type of optical limiting chromo-phores based on new π-expanded pophyrins (Fig. 1).

Literature: [1] Liu, Z.-Q.; Fang, Q.; Cao, D.-X.; Wang, D.; Xu, G.-B. Org. Lett. 2004, 6, 2933. [2] Spangler, C. W. J. Mat. Chem. 1999, 9, 2013. [3] Calvete, M.; Yang G. Y.; Hanack, M. Synthetic Metals 2004, 141, 231.

Acknowledgment: Financial support of our work from the Foundation for Polish Science (Grant number TEAM/2009-4/3) is gratefully acknowledged.

Posters


Fig.1 Different types of intermolecular hydrogen bonds between

6-aminocoumarin (6AC) and protic solvents.

Hydrogen bonds energy changes upon excitations of a minocou-marins determined from absorption solvatochromic ex periment

Krystkowiak E.1, Maciejewski A.1

1 Faculty of Chemistry, Adam Mickiewicz University, [email protected]

Absorption spectra of three aminocoumarins (6-aminocoumarin, 6AC and 7-

aminocoumarins: Coumarin 120, C120, Coumarin 151, C151) were recorded in a series of non-specifically and specifically interacting solvents, especially in polyfluorinated alcohols (HFIP, TFE). An unusual blue-shift of a long-wavelength in absorption spectra of 6AC, C120 and C151 in HFIP and 6AC in TFE and water was observed. With reference to theoretical results [1-3] it was interpreted as the experimental proof of significant weakening of hydrogen bond formed by the amino group nitrogen atom of the aminocoumarin molecule with the hydrogen atom of solvent

molecule (blue bond in Fig. 1) upon photoexcitation to the electronically excited S1-LE state. Moreover, our results obtained for 6AC in HFIP, TFE and water also indicated that upon this transition the decrease in energy for this type of hydrogen bond was much greater than the increase in energy of hydrogen bonds formed by the carbonyl oxygen atom and the hydrogen atom of a protic solvent molecule (red bonds in Fig. 1).

Comparison of the solvatochromic data obtained for three aminocoumarins studied in a few 1-chloro-n-alkanes of different solvent polarity function, f(ε,n2), and in DMSO, permits conclud-ing that upon the S0→S1-LE excitation of aminocoumarins the energy of hydrogen bonds formed by hydrogen atoms of the amino group and the oxygen atom of DMSO as well as of a protic solvent molecule (green bonds in Fig. 1) significantly increases. These results are consis-tent with those of the theoretical calculations [1-2].

In this study we applied simple procedure, proposed by us in Ref. [4] for accurate determina-tion of the hydrogen bonds energy changes as a result of transition from the ground to excited state. This procedure is based on analysis of the absorption spectra of the compound studied in the solvents interacting with it exclusively nonspecifically (1-chloro-n-alkanes) and in those forming only one type of hydrogen bonds with it (HFIP and DMSO respectively).

[1] Y. Liu, J. Ding, D. Shi, J. Sun, J. Photochem. Photobiol. A, 201, 203 (2009) [2] P. Zhou, P. Song, J. Liu, K. Han, G. He, Phys. Chem. Chem. Phys., 11, 9440 (2009) [3] G. –J. Zhao, J. –Y. Liu, L. –C. Zhou, K. –L. Han, J. Phys. Chem. B, 111, 8940 (2007) [4] E. Krystkowiak, K. Dobek, A. Maciejewski, J. Photochem. Photobiol. A, 184, 250 (2006)

Posters


Fluorescent properties of Rhodamine 6G in different xerogel

nanolayers and bulk materials

A. Lewkowicz1 , A. Synak1, B. Grobelna2 , D. Jankowski1, P. Bojarski1

1 Institute of Experimental Physics, University of Gdańsk, [email protected]

2 Faculty of Chemistry, University of Gdańsk

The sol-gel derived materials can be exploited for the different applications, including lumi-nescent materials, potential active media for compact tunable lasers or functional bioinspired nanomaterials. In particular, titanium dioxide as the matrix for Rhodamine 6G molecules has been prepared in the sol- gel process. The obtained material is highly luminescent and durable. Spectacular increase of luminescence signal can be further obtained by spin coating Rhoda-mine 6G doped xerogel nanolayer over silver or gold 50 nm thick film. In this case strong direc-tional emission of Rhodamine 6G is observed as a result of interaction between surface plas-mon and molecular transition moment.

Incorporation of Rhodamine 6G at its high concentrations, results in the observation of strongly modified steady-state and time – resolved luminescent characteristics. These changes have been so far a subject of controversy in recent literature.

In particular, our studies performed in nanolayers and bulk materials using a variety of steady - state and time - resolved techniques help to understand the changes observed in terms of dye aggregation and/ or inner filter effects.

This research has been partly supported within the International PhD Project “Physics of future quantum- based information technologies” (MPD/2009- 3/4) financed by the Foundation for Polish Science. This research has been partly supported by the European Social Fund as a part of the project "Educators for the elite - integrated training program for PhD students, post-docs and professors as academic teachers at University of Gdansk" within the framework of the Human Capital Operational Programme, Action 4.1.1, Improving the quality of educational offer of tertiary education institutions.

[1]P. Bojarski, A.Matczuk, C.Bojarski, A.Kawski, B. Kukliński, C.śurkowska, H.Diehl, Chem.Phys. 210 (1996) 485. [2] F. Del Monte and D.Levy, J.Phys.Chem.B, 130 (1999) 8080. [3] A. Anedda, C.M. Carbonaro, R. Corpino, P.C. Ricci, S. Grand, P.C. Mustarelli, J. Non- Cryst. Solids 353 (2007) 481. [4] Simeonika Rangełowa-Jankowska, Dawid Jankowski, Beata Grobelna, Ignacy Gryczyński, Zygmunt Gryczyński, Robert Bogdanowicz, Piotr Bojarski, ChemPhysChem | DOI: 10.1002/cphc.201100252, Surface-Plasmon-Coupled Emission of Rhodamine 110 in a Silica Nanolayer.

Posters


New Fluorescent Sensors Based on 1 H-Pyrazolo[3,4- b]Quinoline

Skeleton.

Marek Maca, Tomasz Uchacza, Andrzej Danelb.

a) 1 Faculty of Chemistry, Jagiellonian University, 30-060 Krakow, Ingardena 3 b) Department of Chemistry, University of Agriculture, 31-149 Kraków, Balicka 122, Po-

land E-mail: [email protected]

Novel fluorescing dyes 1,3,4-triphenyl-6-(1,4,7,10-tetraoxa-13-aza-cyclopentadec-13-ylmethyl)-1H-pyrazolo[3,4-b]quinoline (K1), 2-[(2-hydroxyethyl)-(1,3,4-triphenyl-1H-pyrazolo[3,4-b]quinolin-6-ylmethyl)-amino]ethanol (L1) and bis-(pyridin-2-yl-methyl)-(1,3,4-triphenyl-1H-pyrazolo[3,4-b]quinolin-6-ylmethyl)-amine (P1) have been synthesized and investigated by the means of steady state and time-resolved fluorescence techniques [1,2]. These compounds act as sensors for the fluorescence detection of small inorganic cations (lithium, sodium, barium, magnesium, calcium and zinc) in solvents of high polarities such as acetonitrile. The mecha-nism, which allows application of these compounds as sensors, is an electron transfer from the electron-donative part of molecule to the acceptor part (fluorophore), which is retarded upon complexation of the electron-donative part by inorganic cations. We found that crown ether-containing compound is very sensitive to the addition of any investigated ions but amino alco-hol-containing one exhibits better selectivity to the addition of two-valued cations. Two kinds of the complexes (LMn+ and L2M

n+) were found in the investigated systems. We found that com-pound P1 is very sensitive to the addition of Zn++ cations. It shows very high selectivity to the addition of the investigated cations [2]. Moreover, the dyes (K1 and L1) may be used as fluo-rescence indicators in solvents of lower polarity like tetrahydrofuran [1].

O

O

O

N

O N NN K1

N NN

NOH

OH

L1

N

N N NN

N P1

[1] M. Mac, T. Uchacz, T. Wróbel., A. Danel, E. Kulig J. Fluoresc., 20, 525, 2010. [2] M. Mac, T. Uchacz, A. Danel, K. Danel., P. Kolek, E. Kulig , J. Fluoresc., 21, 375, 2011.

Posters


12000 16000 20000 24000 28000

0

2

4

6

8

10

12

14

0

2

4

6

8

10

12

14

wavelenght (nm)

fluor

esce

nce

inte

nsity

[a.u

.]

wavenumber [cm-1]

298K 243K 223K 203K 163K 143K 123K 103K 93K

λext

=310 nmVDCF in PrOH

800 700 600 500 400

Fig. 1 Luminescence of VDCF in n-propanol as a

function of temperature.

Solvent controlled photophysics of spirocyclic lact ones

Majka A., Karpiuk J.

Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52,

01 – 224 Warsaw, [email protected]

Spirocyclic rhodamine lactones (LRB, LR101 ) provide a unique example of adiabatic photo-chemistry – their dual fluorescence comes from a highly polar CT state (1LCT) formed after elec-tron transfer (ET) from xanthene to phthalide subunit and an excited state of the open ring form (1Z) populated upon photodissociation of the C–O bond in the lactone ring [1-3]. The branching into the deactivation pathways leading to 1LCT and 1Z states occurs in non-relaxed vibronic levels and the lack of long term (ns) kinetic correlation proves that the emitting states are not in equilibrium. The 1LCT deactivates to the ground state by radiative and non-radiative back ET. The main deactivation channel of the 1Z state is the intersystem crossing to the triplet manifold [4] and the deactivation rate of the 1Z state critically depends on solvent polarity, which is a factor controlling the energy gap between the 1Z state and higher triplet levels of the Z form.

O

O

N(C2H5)2(C2H5)2N

O

O

N N

O

O

(C2H5)2N

O

O

(C2H5)2N

BrO

O

(C2H5)2N

LRB LR101 ODCF VDCF RDCF Recently, we extended our research to include LRB analogs with asymmetrically substituted

(ODCF, VDCF) or modified (RDCF) electron-donating xanthene moiety. All these molecules display dual fluorescence from 1LCT and 1Z states, though the latter emission is observed in a much narrower range of solvent polarity than for LRB (Fig. 1) and requires specific combinations of solvent polarity and dielectric relaxation time. These findings prove that adiabatic photodissociation is a general feature of spirocyclic donor-acceptor systems and that the inter-system crossing plays a major role in photophysics of rhodamines, especially when the Z form is populated in absence of hydrogen bonding with the solvent. A detailed study of VDCF photophysics as a

function of solvent polarity and proticity will be presented and compared with those of ODCF, RDCF and LRB .

[1] U. K. A. Klein, W. F. Hafner, Chem. Phys. Lett. 43, 141 (1976) [2] T. M. Grigoryeva, V. L. Ivanov, N. Nizamov, M. G. Kuzmin Dokl. Akad. Nauk 232, 1108 (1977) [3] J. Karpiuk, Z. R. Grabowski, F. C. De Schryver J. Phys. Chem. 98, 3247 (1994) [4] J. Karpiuk, J. Luminesc. 60-61, 474 (1994)

Posters


Fig.1 Excitation/fluorescence map.

Analysis of the absorption and emission spectra of Photofrin

Pszona M., Waluk J.


Photofrin, known as porfimer sodium, is a porphyrin derivative used in the photodynamic

therapy (PDT) of tumors. Analysis of this photosensitizing agent is a challenging task as Pho-tofrin is a mixture of oligomers formed by porphyrin units linked through ether and ester bonds [1].

Analyses using different mass spectral ionization techniques provided distribution of the oligomers obtained with desalted Photofrin, which consists of two to eight porphyrin units with average 2.5-2.9 [2].

We obtained excitation/fluorescence map for methanol solution of Photofrin II and used principal component analysis (PCA [3]) as a way to obtain the number of components in the mixture, their excita-tion and emission spectra.

The obtained results show that the first principal component is significantly larger than the others. Moreover, it pro-vides 99% of total variance. This could mean that there is only one dominant oligomer in Photofrin or that the emission and excitation spectra of all compounds

are very similar and make this method not applicable in estimating the distribution of oligomers. The apparent homogeneity of Photofrin emission was confirmed by the finding that the investi-gation of fluorescent lifetimes showed only one decay component.

[1] Photofrin (porfimer sodium), Highlights of prescribing information, http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=5c4841b4-fbc0-4163-8ee1-cb28629cbfbf [2] M. M. Siegel, K. Tabei, R. Tsao, M. J. Pastel, R. K. Pandey, S. Berkenkamp, F.Hillenkamp, M. S. de Vries, J. Mass. Spectrom. 34, 661-669 (1999) [3] R. Wehrens, Chemometrics with R: Multivariate Data Analysis in the Natural Sciences and Life Sciences (Springer-Verlag, Berlin, 2011)

Posters


0

50

100

150

200

250

1800022000260003000034000

wavenumber [1/cm]

fluo

resc

ence

[a.u

.]

Fig.1 Effect of TEA/Acetic acid, 10-310 mM, on the fluo-rescence of 8-aza-2,6-diaminopurine in isopropanol.

8-Azapurines: fluorescent, isosteric alternatives t o natural purine

bases

Wierzchowski J., Medza G.

Department of Physics & Biophysics, Faculty of Food Sci., University of Warmia & Mazury in Olsztyn, [email protected]

Natural purines and pyrimidines, or nucleic acid bases, as well as the corresponding nucleo-

sides/nucleotides, are characterized by very low fluorescence yields (~10-4) and low picosecond excited state lifetimes in neutral aqueous media [1]. Although many fluorescent base and nu-cleoside/nucleotide analogues are known [2], their application to biological research is in many cases limited because of bulkiness of the applied modifications, thus interfering with biological systems studied. The present paper summarizes room-temperature fluorescence properties of 8-azapurines, which are isosteric, and biologically active analogues of the natural purines: ade-nine, guanine, and so on. Special attention will be devoted to the photon-induced tautomerism in the foregoing class of compounds, recently reviewed by us [3].

Fluorescence properties of 8-azaadenine, 8-azahypoxanthine and 8-azaguanine, and the corresponding nucleosides, were described several years ago [4]. These compounds were

successfully applied in polynucleotide and ribozyme research [5,6]. Recently, we have found that 8-azaxanthine [7], 8-azaisoguanine [8], and 8-aza-2,6-dimethylaminopurine (unpublished) exhibit moderate to intense fluorescence in aqueous media. Some of the foregoing compounds undergo excited-state intermolecular proton transfer [3,7,8], which makes them particularly interesting candidates for the biophysical applications.

This work will show some unpublished data on phototautomeric behaviour of 8-azaisoguanine, 8-aza-2,6-diaminopurine, and some of their N-methyl derivatives. In particular,

deuterium isotope, solvent, and buffer concentration effects on the room-temperature fluores-cence were studied, with results exemplified in Fig. 1.

[1] M. Daniels, in: Photochemisty and photobiology of nucleic acids, vol. 1 , Chapt. 2, Academic, 1976. [2] R.W. Sinkeldam, N.J. Greco, Y. Tor, Chemical Reviews 110, 2579 (2010) [3] J. Wierzchowski, Current Topics in Biophysics online (Poznan) 33, 9 (2010) [4] J. Wierzchowski, B. Wielgus-Kutrowska, D. Shugar, Biochim. Biophys. Acta 1290, 9 (1996) [5] L. Liu, J.W. Cottrell, L.G. Scott, M.J. Fedor, Nature Chemical Biology 5, 351 (2010) [6] D. Jiang , F. Seela, J. Amer. Chem. Soc. 132, 4016 (2010) [7] J. Wierzchowski, J., Sepioł, D. Sulikowski, B. Kierdaszuk, D. Shugar, J. Photochem. Photobiol. A: 179, 276 (2006). [8] J. Wierzchowski, G. Mędza, D. Shugar, Clollections Symp. Series 10, 476 (2008)

Notes


book of abstractsichf.edu.pl/ml2011/files/ml2011_boa.pdf · 2011-09-16 · peter vöhringer,...

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