Photoinduced electron transfer in amino acid assemblies

Article abstract of DOI:10.1021/ja00066a017

The preparation and photophysical characterization of a of redox-active lysines and related model compounds based on polypyridyl ruthenium complexes are described. Donor-chromophore-acceptor triad 1, [PTZpn-Lys(Ru^IIb₂m)²⁺-NH-prPQ²⁺] (PF₆^-)₄ (see below), by of a bipyridyl caromophore (Ru^IIb₂m, where b = 2,2′-bipyridine, m = 4′-methyl-2,2′-bipyridyl-4′-carbonyl), an electron donor (phenothiazine, PTZ), and an (paraquat, PQ²⁺) on a (Lys) scaffold utilizing bonds. This derivatized amiono acid exihibited efficient (>95%) quenching of the ruthenium metal-to-ligand charge-transfer (MLCT) excited state upon irradiation with a 420-nm laser pulse in CH₃CN. The resulting state, [(PTZpn⁺)-Lys(Ru^IIb₂m) ²⁺-NH-(prPQ⁺)]) 1.17 eV and lived for 108 ns (k = 9.26 × 10⁶ s^-1) as observed by transient absorption spectrosoopy. Also studied was a of related model systems that included model chroaophores, simple chromophore-quencher dyads linked by amide bonds, and chromophore-queneher dyads on lysine. An account of the of kinetic behavior of these system including triad 1 and a discussion of factors that influence the lifetime of the redox-separated states, their efficiency of formation, their energy storage ability are presented.