The functional core of oxygenic photosynthesis is in charge of catalytic water oxidation by a multi-redoxMnIII/MnIV manifold that evolves through five electronic states (Si , 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 [MnIII 3MnIVO3(CH3COO)3(A-a-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%.
Photo-catalytic Water Oxidation by a Mixed-Valent MnIII3MnIVO3 Manganese-Oxo-Core mimicking the Natural Oxygen Evolving Center
NATALI, Mirco;SCANDOLA, Franco;
2014
Abstract
The functional core of oxygenic photosynthesis is in charge of catalytic water oxidation by a multi-redoxMnIII/MnIV manifold that evolves through five electronic states (Si , 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 [MnIII 3MnIVO3(CH3COO)3(A-a-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%.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.