PRODUCTION AND STORAGE OF MULTIPLE, PHOTOCHEMICAL REDOX EQUIVALENTS ON A SOLUBLE POLYMER

Soluble polymers have been prepared that contain high loadings of metal-to-ligand charge-transfer (MLCT) visible-light absorbers based on polypyridyl complexes of RuIIor OsII. The complexes have been attached to a styrene/chloromethylstyrene copolymer by nucleophilic displacement of the chloro groups. By using excesses of the complexes, complete substitution at the available ~30 chloro-methylated sites was achieved. A series of mixed-valence polymers with controlled MIII/MIIratios has been prepared in acetonitrile or acidic aqueous solution by oxidation with Ce(IV). For the OsII-containing polymers, OsII⋆-based MLCT excited-state lifetimes and emission quantum yields are relatively unaffected by the OsIII/OsIIratio. This shows that intramolecular oxidative quenching of OsII⋆by OsIIIis slow. The slow rate of electron-transfer quenching is a manifestation of the “inverted region”. Because excited-state properties are relatively unaffected in the mixed-valence polymers, it is possible to build up and store ~30 oxidative equivalents on individual polymeric strands by photochemical oxidation. © 1990, American Chemical Society. All rights reserved.