************OWARI COMPLEX SEMINAR LXI*************

Title : Computational Chemistry Studies on 
        Molecular Wires and Diodes

Speaker : Prof. Ahmed M. El-Nahas

Affiliation : Chemistry Department, 
              Faculty of Science, 
              El-Menoufia University, 
              Shebin El-Kom, Egypt

Date : Mon. Apr. 7th, 13:30 pm (Almost one hour)

Place : 3F Seminar Room, Graduate School of 
        Information Science

Abstract :
We are interested in reaction mechanisms of metal-
loenzymes where transition metals are included, 
and address water splitting reaction catalyzed by 
the oxygen-evolving complex (OEC) that consists of 
one calcium and four manganese in this seminar. 
The 4-electron oxidation of two water molecules, 
which is known as the first reaction step in 
oxygenic photosynthesis, is catalyzed by OEC. The 
reaction mechanism has not been established yet 
since detailed 3-D structures of OEC have been un-
available for a long time. In 2011, the chemical 
composition of CaMn4O5 core and the positions of 
surrounding water molecules in the active site were 
identified from the high resolution X-ray crystal-
lography. However, protonation states of substrates 
and individual oxidation state of Mn atom in 
intermediates during the catalytic cycle have been 
unclear. Furthermore, the CaMn4O5 core has various 
spin configurations since the d-electrons of Mn 
atom are strongly correlated, and thus it is 
difficult to analyze the electronic structures. 
Using the broken-symmetry and density functional 
theory (B3LYP) methods which are successful in 
such a system, we have investigated the reaction 
mechanism.

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