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Title: A molecular model of artificial photosynthesis: Mn-Ca binuclear complex for photosynthetic oxidation of water
Authors: Mishra, Nibedita
Mohapatra, Pranab Kishor
Raval, Mukesh Kumar
Biswal, Basanti
Biswal, Uday Chand
Keywords: Molecular modeling;Photosynthetic water oxidation;Photosystem II;Quantum mechanical calculations;Oxygen evolving complex;Mn-Ca binuclear complex
Issue Date: Aug-2012
Publisher: NISCAIR-CSIR, India
Abstract: The redox active component of oxygenic photosynthetic reaction center II contains metal cluster Mn4-Ca, where two H2O are oxidized to O2 and four H+ ions are liberated. A binuclear Mn-Ca metal center binding one substrate H2O on each ion is proposed to be the minimal unit of the redox center. A model for the water oxidizing metal cluster is built with molecular modeling software (HyperChem 8.0 Pro). Mn, being a transitional metal with variable valency is redox active, while Ca is redox inert. Formation and deprotonation of H2O˙+ on MnIII may be favorable compared to Ca. Deprotonation of H2O˙+ yields a stable species HOˉ on MnIV by transfer of one electron from MnIII as a consequence of first photoact. Similarly, during second photoact, it may lead to formation of MnV = O. The O-O bond may be formed in the third photoact between O on Mn and H2O on Ca. Subsequently, HO2˙ˉ may be formed, leading to formation of O2. Molecular models are built for each transition states.
Page(s): 246-249
ISSN: 0975-0959 (Online); 0301-1208 (Print)
Appears in Collections:IJBB Vol.49(4) [August 2012]

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