contents: introduction. natural photosynthesis. antenna effect. chromophores used in artificial...
TRANSCRIPT
![Page 1: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/1.jpg)
![Page 2: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/2.jpg)
Contents:
Introduction.
Natural Photosynthesis.
Antenna Effect.
Chromophores used in Artificial photosynthetic arrays:
Porphyrins
Dendrimers
Fullerenes
Rylenes
Conclusion.
![Page 3: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/3.jpg)
Introduction
165,000 TWof sunlighthit the earthevery day
165,000 TW of sunlightstrike the earth every day.
![Page 4: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/4.jpg)
blue green orange red
Electromagnetic spectrum
![Page 5: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/5.jpg)
NATURAL PHOTOSYNTHESIS
![Page 6: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/6.jpg)
Schematic representation of bacterial light harvesting complexes.
N.W.Isaacs et al, Nature, 1995, 374, 517
![Page 7: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/7.jpg)
Antennae
Light Excitation transfer
Pigment molecules
Electron transfer
e - acceptor
e- donor
Antenna Effect
![Page 8: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/8.jpg)
Requisites for light harvesting:
Absorption of visible light.
Stability to photolysis.
Efficient energy transfer process.
High energy content.
Long lived excited state.
Appropriate kinetic factors.
![Page 9: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/9.jpg)
Pen
RC
Pen
PenPen
C C
C C
h
h h
hh’
E E
EE
Pen : Energy transfer photosensitiser.
RC : Reaction Centre
C : Connectors
Intramolecular Light Harvesting systems : Testing the efficiency of energy transport
![Page 10: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/10.jpg)
e¯
e¯h h h h h h h
ReI
PeI Pen Pen PenPen Pen Pen
R’eI
Fujihira et al, Thin Solid Films, 1989, 180, 43
Pen
Rel Pel R’el
Light harvesting on monomolecular layer assembly
Pel : Electron transfer photosensitiser
Pen: Energy transfer photosensitiser
Rel: Electron relay
![Page 11: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/11.jpg)
Meyer.T.J.et al ,J. Am. Chem. Soc. 1989, I l l , 9101
Remote Photosensitisation
![Page 12: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/12.jpg)
Synthetic multiporphyrin arrays have been frequently prepared to shed light on light harvesting processes.
Porphyrins are more stable and accessible synthetically than chlorophylls.
Absorption properties: strongly in the blue and weakly or moderately in the green regions.
Porphyrins:
![Page 13: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/13.jpg)
Dyad
Q
P
Yanagita.M., et al, Tetrahedron Lett, 1979, 20, 257
1
2
3
![Page 14: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/14.jpg)
C-P-Q Triad
Moore.T.A., et al., Nature, 1984, 307, 630
C
C-P-Q
C-1P-Q
C-P+-Q-
C+-P-Q-
0.0
1.0
2.0
Ene
rgy
(eV
)
1
2
3
5
4
PQ
= 2µs (in butyronitrile)= 300ns (in CH2Cl2)
![Page 15: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/15.jpg)
Gust, D., et al, J. Am. Chem. Soc. 1997, 119, 1400.
C P C60
Triad
C-P-C60
C-1P-C60
C-P-1C60
C-P+-C60–
1[C+-P-C60– ] 3[C+-P-C60
–]
3[C-P-C60]
1
2
3
4
5 6 7
8
109
11
E (eV)
= 4.9µs (in MTHF)
![Page 16: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/16.jpg)
N
N
N
Ru N
N
N
N
NH N
HN N
N N
NAu
Sauvage.J.P., et al, Chem. Soc.Rev., 2004, 33, 147
Triad
= 75 ns (in CH3CN)
![Page 17: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/17.jpg)
+–
+–
Tetrad
Gust.D.,Moore.T.A., et al, Science, 1989, 244, 35
= 460ns
![Page 18: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/18.jpg)
Fukuzumi.S, Guldi,D.M et al, J.Am.Chem.Soc. 2001, 123,
6617
Tetrad
+ –
= 0.38s
![Page 19: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/19.jpg)
Pentad
Gust.D,Moore.T.A et al, Science, 1990, 248, 199
–+
C PZn PH QN QB
= 55 µs
![Page 20: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/20.jpg)
Hexad
Gust. D., Lindsey.J, et al, J.Am.Chem.Soc. 1999, 121, 8604
energy transfer 50 ps
energy transfer 244 ps
charge separation 3 pscharge recombination 1330 ps
![Page 21: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/21.jpg)
Lindsey, J., et al, J. Org. Chem. 1999, 64, 9101.
Increasing the spectral coverage
abs em
![Page 22: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/22.jpg)
Lindsey, J. et al Org. Lett., 2000, 2, 17
Self Assembly of Light Harvester / Reactive Chromophore Assemblies
![Page 23: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/23.jpg)
They are nanoscale macromolecules which are highly branched polymers with precisely controlled architectures.
Dendrimers:
![Page 24: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/24.jpg)
Balzani V, Lehn J-M, et al, Angewandte Chemie, 1987, 26, 1266
![Page 25: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/25.jpg)
Moore et al, Angewandte Chemie, 1993, 32, 246
![Page 26: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/26.jpg)
Armaroli N. et al, Chem.Eur.J, 2003, 9, 37
![Page 27: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/27.jpg)
Potential uses and positioning of metals within dendritic architectures
Newkome.G.R., et al,Chemical Reviews, 1999, 99, 1689
![Page 28: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/28.jpg)
Aida.T. et al, Chem.Eur.J. 2002, 8, 2667
Zn-P
H2-P
h’
h
![Page 29: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/29.jpg)
Balzani.V., et al, Coord Chemistry Reviews, 2001, 219–221, 545
Dendrimers with metal complexes in each branching centre.
![Page 30: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/30.jpg)
Light harvesting and antenna effect
Balzani.V., et al, Coord.Chem.Reviews, 2001, 219–221, 545.
- Os2+
- Ru2+
![Page 31: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/31.jpg)
Balzani.V., et.al, New. J. Chem., 1999, 23, 63
Dendrimer having a metal complex as the core
![Page 32: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/32.jpg)
RYLENES
Wasielewski.M.,et al, J.Am.Chem.Soc, 2004, 126, 12268
![Page 33: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/33.jpg)
Conclusion:Artificial photosynthetic arrays by theincorporation of various chromophores have been looked into.
These arrays mimic certain aspects of natural photosynthetic systems.
According to Giacomo Ciamician:“The photochemical processes, that hitherto have been the guarded secret of the plants, will have been mastered by human industry which will know how to make them bear even more abundant fruit than nature, for nature is not in a hurry but mankind is.”
![Page 34: Contents: Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers](https://reader035.vdocuments.net/reader035/viewer/2022062309/5697bf7b1a28abf838c8384e/html5/thumbnails/34.jpg)
Acknowledgements
Dr. Russell H. Schmehl
Dr. Mark J. Fink Dr. James P. Donahue
Group Members: Dr. Kumaresan Duraisamy Heidi Hester Srivathsa Vaidya Rupesh Narayana Prabhu David Karam Chemistry Department, Tulane University