Photochemical conversion of solar energy

Ru(CN)jNO reactions with OH , SH and SOj" resemble those of the nitroprusside ion, with attack at the coordinated nitrosyl to give analogous transients and similar second-order rate constants. Ruthenium(II) complexes of the general type Ru(N2), Nj = biden-tate hgands, are important reactants. The relative inertness of Ru(NH3) + and Ru(diimine)f+ towards substitution makes these complexes definite, although weak, outer-sphere reductants (Tables 5.4, 5.5, 5.6 and 5.1). Ruthenium(ll) complexes of the general type Ru(diimine)f +, and particularly the complex Ru(bpy)j+, have unique excited state properties. They can be used as photosensitizers in the photochemical conversion of solar energy. Scheme 8.1 ... 

A model proposed for photochemical conversion of solar energy 11,14) is shown in Fig. 3. The system is made of a photoreaction couple, two kinds of electron mediator, and reduction as well as oxidation catalysts. It is designed to share the necessary functions among the various compounds because it would be difficult for one single compound to bear all the functions. A single component carrying out the total conversion would of course be the best system. 

Fig. 3. A model system for photochemical conversion of solar energy. R2 Reducing agent, R, Oxidizing agent C2 Oxidation catalyst Cj Reduction catalyst T2, T, Electron mediators P2-Pj = P Photoreaction center...

Photochemical conversion of solar energy in artificial systems (as in natural photosynthesis) is essentially based on electron-transfer between an excited photosensitizer (A ) and an appropriate electron acceptor (B)... 

Aresta, M., Quaranta, E., and Tommasi, I. (1991) Photochemical Conversion of Solar Energy (eds E. Pelizzetti and M. Schiavello), Kluwer Academic Publishers, Dordrecht, The Netherlands, p. 517. 

Balzani V, Credi A, Venturi M. Photochemical conversion of solar energy. ChemSusChem 2008 1 26-58. 

On the basis of the studies reported in the last few years, it is elear that the reeent significant progress both in mapping the natural systems and in designing sophisticated artificial systems has been made possible by the recent notable advaneements of experimental techniques and made-to-order synthesis. Beeause both the experimental techniques and made-to-order synthesis are continuing to improve fast at the moment, further impressive developments in the field are expected in the near future [48], so bringing the photochemical conversion of solar energy eloser. 

E. Pelizzetti, M. Sciavello (Eds), Photochemical Conversion of Solar Energy, Kluwer, Dordrecht, 1991. 

In the photochemical conversion of solar energy, it may prove possible to use colloidal semiconductors dispersed in polymerised vesicles. 

Dube S, Sharma SL (1994) Studies in photochemical conversion of solar-energy - simultaneous use of 2 dyes with mannitol in photogalvanic cell. Energy Convers Manage 35 709... 

Enormous interest shown on the photochemistry of transition metal polypyridyl complexes in fact is linked to these type of applications in the domain of photochemical conversion of solar energy. Practically every metal complex with fully or partially characterized electronically excited state has been examined as a means of generating key oxidants and/or reductants required and some have shown partial success. A number of reviews of these topics are available [63-65] and hence only the basic principles and summary of progress in these areas will be indicated. 

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