Triads with Porphyrin-Quinone Components

Several triads (as well as more complex systems, tetrads, pentads, etc.) have been successfully developed making use of organic molecular components [211-213], some of which (porphyrins, quinones, carotenoids) are reminiscent of those found in the natural systems (for detailed accounts, see Volume III, Part 2, Chapters 1 and 2). Remarkable efficiencies and lifetimes of charge separation have been reached with such systems. Their potential has been impressively demonstrated by incorporation into liposomal membranes performing the photo-driven synthesis of ATP [214]. 

So far, a variety of synthetic polychro-mophoric model systems, that is, triads, tetrads, pentads, and so on, have been studied in connection with photosynthesis and reported by several groups [70-88]. The electron-transport components, porphyrins, quinones, aromatic imides, and fullerenes are commonly employed by... 

Additionally, Hunter and coworker presented another model for the noncovalently linked donor-acceptor complex which was made up of triad components, quinone-cyclophane-porphyrin 144. H NMR measurements indicated the formation of a ternary complex and the association constant of BQ via hydrogen bonds was determined to be 1.4 x 10 M, while the association constant of pyridine of the cyclophane and zinc porphyrin was 3.2 X lO M in dichloromethane. The fluorescence emission from the zinc porphyrin in the presence of the cyclophane was clearly quenched by the addition of BQ, compared with a control experiment, due to diffusional quenching. This evidence indicated that the intracomplex ET occurred within the triad system. 

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