Oligomer and mixed-metal compounds potential multielectron transfer agent

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We proposed to continue syntheses and characterizations of monometallic and multimetallic compounds on work in progress, extend our efforts to prepare and design molecules of interest for intramolecular electron and energy transfer, determine the photophysics of ligand loss from ruthenium(II) monometallic complexes and examine catalytic properties of our complexes. We have successfully made contributions toward each of these goals. The preparation and properties of both homonuclear (same metal center) and heteronuclear (different metal centers) complexes containing from one to four metal centers were reported. New complexes of rhenium(I) and platinum(II) which emitted strongly in solution and underwent excited state electron transfer were synthesized. A bimetallic complex containing rhenium(I) and ruthenium(II) exhibited unusual properties. Luminescence was observed from each metal core. The photophysics of tris-chelated ruthenium(II) and bis-chelated, bispyridine ruthenium(II) complexes was examined. Temperature dependent emission lifetimes were attributed to either energy loss through a fourth charge transfer excited state, the third MLCT state, or the dd state, depending upon the complex in question. Catalytic properties were examined at surface modified electrodes. Significant photocurrents were observed in carrageenan, a polysaccharide hydrogel. Two hydrogel systems were examined. These were: (a) one containing Ru(bpy){sub 3}{sup 2+}, methyl viologen and triethanolamine, and (b) one containing Ru(bpy){sub 3}{sup 2+}, oxygen and triethanolamine. Catalytic CO{sub 2} reduction was also examined at a bare platinum electrode, at a bare platinum electrode in a solution containing Co(bpy){sub 3}{sup 3+} as a homogeneous catalyst, and at a platinum electrode whose was modified with a cobalt bipyridine-like material.