1 / 34

ARTIFICIAL PHOTOSYNTHETIC ARRAYS

ARTIFICIAL PHOTOSYNTHETIC ARRAYS. Contents:. Introduction. Natural Photosynthesis. Antenna Effect. Chromophores used in Artificial photosynthetic arrays: Porphyrins Dendrimers Fullerenes Rylenes Conclusion. Introduction. 165,000 TW of sunlight hit the earth every day.

julian-mann
Download Presentation

ARTIFICIAL PHOTOSYNTHETIC ARRAYS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ARTIFICIAL PHOTOSYNTHETIC ARRAYS

  2. Contents: • Introduction. • Natural Photosynthesis. • Antenna Effect. • Chromophores used in Artificial photosynthetic arrays: • Porphyrins • Dendrimers • Fullerenes • Rylenes • Conclusion.

  3. Introduction 165,000 TW of sunlight hit the earth every day 165,000 TW of sunlight strike the earth every day.

  4. blue green orange red Electromagnetic spectrum

  5. NATURAL PHOTOSYNTHESIS

  6. Schematic representation of bacterial light harvesting complexes. N.W.Isaacs et al, Nature, 1995, 374, 517

  7. Light Excitation transfer Electron transfer Pigment molecules e - acceptor Antennae e- donor Antenna Effect

  8. 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.

  9. Pen C C Pen Pen Pen RC C C Intramolecular Light Harvesting systems : Testing the efficiency of energy transport h h E E E E h h h’ Pen : Energy transfer photosensitiser. RC : Reaction Centre C : Connectors

  10. R’eI PeI Pen Pen Pen Pen Pen Pen ReI Light harvesting on monomolecular layer assembly Pel R’el Rel e¯ Pen e¯ h h h h h h h Pel : Electron transfer photosensitiser Pen: Energy transfer photosensitiser Rel: Electron relay Fujihira et al, Thin Solid Films, 1989, 180, 43

  11. Remote Photosensitisation Meyer.T.J.et al ,J. Am. Chem. Soc. 1989, I l l , 9101

  12. Porphyrins: 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.

  13. 2 3 1 Dyad P Q Yanagita.M., et al, Tetrahedron Lett, 1979, 20, 257

  14. 2.0 C-1P-Q 2 C-P+-Q- Energy (eV) 4 C+-P-Q- 1 3 1.0 5 C-P-Q 0.0 C-P-Q Triad P Q C • = 2µs (in butyronitrile) • = 300ns (in CH2Cl2) Moore.T.A., et al., Nature, 1984, 307, 630

  15. Triad C C60 P C-1P-C60 3 C-P-1C60 2 4 C-P+-C60– 8 3[C+-P-C60–] 1[C+-P-C60–] E (eV) 1 5 6 7 9 10 3[C-P-C60] 11  = 4.9µs (in MTHF) C-P-C60 Gust, D., et al, J. Am. Chem. Soc. 1997, 119, 1400.

  16. Triad  = 75 ns (in CH3CN) Sauvage.J.P., et al, Chem. Soc.Rev., 2004, 33, 147

  17. – + Tetrad – +  = 460ns Gust.D.,Moore.T.A., et al, Science, 1989, 244, 35

  18. Tetrad + –  = 0.38s Fukuzumi.S, Guldi,D.Met al, J.Am.Chem.Soc. 2001, 123, 6617

  19. C PZn PH QN QB Pentad + –  = 55 µs Gust.D,Moore.T.A et al, Science, 1990, 248, 199

  20. Hexad energy transfer 50 ps energy transfer 244 ps charge separation 3 ps charge recombination 1330 ps Gust. D., Lindsey.J, et al, J.Am.Chem.Soc. 1999, 121, 8604

  21. Increasing the spectral coverage abs em Lindsey, J., et al, J. Org. Chem. 1999, 64, 9101.

  22. Self Assembly of Light Harvester / Reactive Chromophore Assemblies Lindsey, J. et al Org. Lett., 2000, 2, 17

  23. Dendrimers: They are nanoscale macromolecules which are highly branched polymers with precisely controlled architectures.

  24. Balzani V, Lehn J-M, et al, Angewandte Chemie, 1987, 26, 1266

  25. Moore et al, Angewandte Chemie, 1993, 32, 246

  26. Armaroli N. et al, Chem.Eur.J, 2003, 9, 37

  27. Potential uses and positioning of metals within dendritic architectures Newkome.G.R., et al,Chemical Reviews, 1999, 99, 1689

  28. Zn-P h H2-P h’ Aida.T. et al, Chem.Eur.J. 2002, 8, 2667

  29. Dendrimers with metal complexes in each branching centre. Balzani.V., et al, Coord Chemistry Reviews, 2001, 219–221, 545

  30. Light harvesting and antenna effect  - Os2+  - Ru2+ Balzani.V., et al, Coord.Chem.Reviews, 2001, 219–221, 545.

  31. Dendrimer having a metal complex as the core Balzani.V., et.al, New. J. Chem., 1999, 23, 63

  32. RYLENES Wasielewski.M.,et al, J.Am.Chem.Soc, 2004, 126, 12268

  33. Conclusion: Artificial photosynthetic arrays by the incorporation 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.”

  34. 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

More Related