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Photocatalytic Water Oxidation by a Mixed‐Valent Mn III 3 Mn IV O 3 Manganese Oxo Core that Mimics the Natural Oxygen‐Evolving Center
Author(s) -
AlOweini Rami,
Sartorel Andrea,
Bassil Bassem S.,
Natali Mirco,
Berardi Serena,
Scandola Franco,
Kortz Ulrich,
Bonchio Marcella
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201404664
Subject(s) - manganese , oxygen evolution , catalysis , chemistry , photocatalysis , artificial photosynthesis , redox , photosynthesis , flash photolysis , oxygen , photodissociation , photochemistry , inorganic chemistry , physics , electrochemistry , reaction rate constant , biochemistry , organic chemistry , electrode , quantum mechanics , kinetics
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 S 0 →S 4 intermediates is the expected turning point for artificial photosynthesis. The tetramanganese‐substituted tungstosilicate [Mn III 3 Mn IV O 3 (CH 3 COO) 3 (A‐α‐SiW 9 O 34 )] 6− (Mn 4 POM) offers an unprecedented mimicry of the natural system in its reduced S 0 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 S 2 O 8 2− is obtained by nanosecond laser flash photolysis; its S 0 →S 1 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 %.