Studies of oxomanganese complexes for natural and artificial photosynthesis

by Ivan Rivalta (Yale University, USA)

Thursday 22 Dec 2011, 14:30 → 16:00 Europe/Rome

Aula Careri (Dipartimento di Fisica - Ed. G. Marconi)

Nature has solved the difficult problem of efficient light-driven, four-electron oxidation of water to O2, by means of a Mn-based catalyst embedded in the Phostosystem II (PSII), a ~350 kDa complex of 20 proteins. The Mn4CaO5 cluster of the oxygen-evolving complex (OEC) of PSII is composed of inexpensive earth-abundant metals (Mn and Ca) and features high turnover rates that are still unmatched by artificial water splitting systems. Elucidating its detailed molecular structure and the catalytic mechanism is crucial for developing new biomimetic catalysts for renewable solar-energy conversion. This talk summarizes our recent advances on studies of PSII and biomimetic oxomanganese complexes for artificial photosynthesis. Our computational studies on PSII, based on the recent crystal structure at 1.9 resolution, introduced a novel model for the OEC resting state and elucidated the structural/functional role of chloride cofactor in PSII. DFT studies on biomimetic oxomanganese complex reveals the role of acetate buffer as acid/base and redox cofactor in the homogeneously catalyzed water-splitting mechanism reaction.