合成,同位体ラベル付け,計算研究に基づく立方体Mn3MO (n) コンプレックスに酸素原子の移転と酸化水の組み込み
Jacob S Kanady1, Jose L Mendoza-Cortes, Emily Y Tsui
1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Journal of the American Chemical Society
|December 18, 2012
まとめ
光システムIIにおけるマンガン・カルシウム・キューブンモデルの反応性は,マンガンの酸化状態だけでなく,リガンドの可変性によって制御されます. この発見は,酸素が進化する複雑なメカニズムに光を当てています.
科学分野:
- 無機化学 無機化学とは
- フォトケミストリー フォトケミストリー
- バイオケミストリー バイオケミストリー
背景:
- 光学系IIの酸素進化複合体 (OEC) は光合成に不可欠であり,Mn{4) CaO{n) 群を特徴としています.
- OEC内のブリッジングオキシド部分の反応性を理解することは,その機能を明らかにするために不可欠です.
- 構造的に関連する立方形の Mn(3) MO(n) 複合体 (M = Mn, Ca, Sc; n = 3,4) をモデルとして合成した.
研究 の 目的:
- Mn(3) MO(n) コンプレックスから酸素原子の移転のメカニズム的経路を調査する.
- OEC反応性におけるリガンド可変性およびマンガンの酸化状態の役割を調査する.
- オキシド移動を含むOECの提案されたメカニズムについての洞察を得るために.
主な方法:
- Mn(3) MO(n) の立方体複合体の合成.
- 酸素原子受容体としてトリメチルフォスフィン (PMe(3) を用いた反応性研究.
- 反応経路を調査するための量子力学的計算.
- (18) オキシドの組み込みを追跡するためのO-ラベリング実験.
主要な成果:
- Mn (((IV) (((3) CaO (((4) と Mn (((IV) (((3) ScO ((4) のモデルは,PMe (((3) に対して無反応であった.
- A Mn ((III) ((2) Mn ((IV) ((2) O ((4) キューバンは,PMe ((3) と反応して,Mn ((III) ((4) O ((3) 部分キューバンを形成した.
- 量子力学は,リガンド (アセテート) の可動性,特にMn (III) が存在する場合,酸素原子の移転を促進することを明らかにしました.
- 部分キューバンの中に酸化酸化物の組み込みが観察され,18O-ラベルが酸化物の移動を支援しました.
結論:
- Mn(3) MO(4) キューバンから酸素原子の移転は,マンガンの酸化状態によってのみではなく,リガンド可変性によって支配されます.
- Mn ((IV) ((3) CaO ((4)) モデルは,その関連性にもかかわらず,反応性がなく,特定の構造的特徴の重要性を強調しています.
- 実験的および計算的発見は,OECクラスター内のオキシド移動を含むメカニズムをサポートしています.
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