Please use this identifier to cite or link to this item: http://nopr.niscair.res.in/handle/123456789/14540
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 Mn<sub>4</sub>-Ca, where two H<sub>2</sub>O are oxidized to O<sub>2 </sub>and four H<sup>+</sup> ions are liberated. A binuclear Mn-Ca metal center binding one substrate H<sub>2</sub>O 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<sup> </sup>is redox active, while Ca is redox inert. Formation and deprotonation of H<sub>2</sub>O<sup>˙+</sup> on Mn<sup>III</sup> may be favorable compared to Ca. Deprotonation of H<sub>2</sub>O<sup>˙+</sup> yields a stable species HOˉ on Mn<sup>IV</sup> by transfer of one electron from Mn<sup>III</sup> as a consequence of first photoact. Similarly, during second photoact, it may lead to formation of Mn<sup>V </sup>= O. The O-O bond may be formed in the third photoact between O on Mn and H<sub>2</sub>O on Ca. Subsequently, HO<sub>2</sub>˙ˉ may be formed, leading to formation of O<sub>2</sub>. Molecular models are built for each transition states.
Description: 246-249
URI: http://hdl.handle.net/123456789/14540
ISSN: 0975-0959 (Online); 0301-1208 (Print)
Appears in Collections:IJBB Vol.49(4) [August 2012]

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