DV-Xα法, マンガン, カルシウム, 光化学系II, 光化学反応, クラスター錯体
Oxygen-evolving center Mn4CaO5 complex in the plant has a unique distorted structure called the "distorted chair-type shape", and Mn4CaO5 plays an important role in the oxygen evolution in plant photosynthesis, due to the distorted structure. We investigated the mechanism of the distorted structure of Mn4CaO5 complex in this study. There are some characteristic atoms in the Mn4CaO5 complex, Ca and Mn(4) atoms, which we should pay attention to, research the effects of Ca and Mn(4) atoms for their interactions to changing the structure by electronic theory using DV-Xα method. As a result, it was found that covalent bonds of the specific inter-atomic binding are enhanced by the existing of the Mn(4) and Ca atoms, and the bonds of another specific inter-atomic binding has been weakened by Ca atom. It is thought that the bond distance is shorter with the enhanced binding, and the bond distance is longer with the weakened binding. This suggests that if the inter-atomic bond is shorter, then another bond length should be longer in Mn4CaO5 complex, due to the Mn and Ca atoms. It is concluded that the changing of the bond distance which appears due to the presence of the Ca and Mn(4) atoms is the cause of the distortion of the structure of Mn4CaO5 complex.
