A molecular model of artificial photosynthesis: Mn-Ca binuclear complex for photosynthetic oxidation of water.
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 HO(-) 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*(-) may be formed, leading to formation of O2. Molecular models are built for each transition states.
Department of Chemistry, Gangadhar Meher College College, Sambalpur, 768004, Odisha, India.
Nibedita
N
Mishra
Pranab Kishor
PK
Mohapatra
Mukesh Kumar
MK
Raval
Basanti
B
Biswal
Uday Chand
UC
Biswal
D032701:Biomimetics; D002118:Calcium / Q000737:chemistry* / Q000378:metabolism; D003408:Cresols / Q000737:chemistry / Q000378:metabolism; D008345:Manganese / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D010788:Photosynthesis; D014867:Water / Q000737:chemistry* / Q000378:metabolism
D003408:Cresols; D014867:Water; C032538:4-cresol; D008345:Manganese; D002118:Calcium