title: Photocatalytic water oxidation by a mixed-valent Mn(III)₃Mn(IV)O₃ manganese oxo core that mimics the natural oxygen-evolving center.
abstract: The functional core of oxygenic photosynthesis is in charge of catalytic water oxidation by a multi-redox Mn(III)/Mn(IV) manifold that evolves through five electronic states (S(i), where i=0-4). The synthetic model system of this catalytic cycle and of its S0→S4 intermediates is the expected turning point for artificial photosynthesis. The tetramanganese-substituted tungstosilicate [Mn(III)3Mn(IV)O3(CH3COO)3(A-α-SiW9O34)](6-)(Mn4POM) offers an unprecedented mimicry of the natural system in its reduced S0 state; it features a hybrid organic-inorganic coordination sphere and is anchored on a polyoxotungstate. Evidence for its photosynthetic properties when combined with [Ru(bpy)3](2+) and S2O8(2-) is obtained by nanosecond laser flash photolysis; its S0→S1 transition within milliseconds and multiple-hole-accumulating properties were studied. Photocatalytic oxygen evolution is achieved in a buffered medium (pH 5) with a quantum efficiency of 1.7%.
authors: ITM-CNR and Dipartimento di Scienze Chimiche, Università di Padova via Marzolo 1, 35131 Padova (Italy) http://www.chimica.unipd.it/NanoMolCat.
authors: Rami
authors: R
authors: Al-Oweini
authors: Andrea
authors: A
authors: Sartorel
authors: Bassem S
authors: BS
authors: Bassil
authors: Mirco
authors: M
authors: Natali
authors: Serena
authors: S
authors: Berardi
authors: Franco
authors: F
authors: Scandola
authors: Ulrich
authors: U
authors: Kortz
authors: Marcella
authors: M
authors: Bonchio
mesh_terms: D002384:Catalysis; D008345:Manganese / Q000737:chemistry*; D017895:Manganese Compounds / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry*; D010782:Photolysis; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000737:chemistry; D017973:Tungsten Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D000099294:Polyoxometalates
chemical_list: D008345:Manganese; D017895:Manganese Compounds; D010087:Oxides; D010100:Oxygen; D045332:Photosystem II Protein Complex; D017973:Tungsten Compounds; D014867:Water; C102296:polyoxometalate I; D000099294:Polyoxometalates
keywords: flash photolysis; manganese; oxygen evolution; polyoxometalates; water oxidation