Tris(2,2'-bipyridine)ruthenium(II) complexes, Ru(bpy)32+, were covalently linked to viologen units to afford a model of man-made photoreaction centers. The emission from the ruthenium complex in the photoreaction centers was almost completely quenched by the linked viologen units. The relative quantum yields ( " ) of the photoinduced reduction of viologen units in the presence of the electron donor EDTA were 1-2% of those for the free Ru(bpy)32+-methyl viologen system in aqueous solutions. The ß values, however, remarkably increased in the combined system which consisted of the photoreaction center and the electron relay systems of aligned viologen units (micelle, polymer, and polysoap). The effect was attributed to the enhancement of charge separation of the photoproduced primary ion pair due to electron injection from the photoreaction centers into the electron relay system and the succeeding electron migration.

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Photosensitized reduction of disodium 9,10-anthraquinonedisulfonate was carried out by the use of vesicles incorporating an amphipathic zinc porphinato complex (ZnC12TPyP) and electron mediators. An extremely rapid electron-transport across the vesicle wall was observed with 1,3-dibutylalloxazine as the electron mediator. Two-step activations of the sensitizer (ZnC12TPyP) at the inner- and outer surfaces of vesicles were suggested to account for the electron-transport.