Homogeneous Photocatalytic Water Oxidation with a Dinuclear CoIII–Pyridylmethylamine Complex

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• 作者：Tomoya Ishizuka ; Atsuko Watanabe ; Hiroaki Kotani ; Dachao Hong ; Kenta Satonaka ; Tohru Wada ; Yoshihito Shiota ; Kazunari Yoshizawa ; Kazuaki Ohara ; Kentaro Yamaguchi ; Satoshi Kato ; Shunichi Fukuzumi ; Takahiko Kojima
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：February 1, 2016
• 年：2016
• 卷：55
• 期：3
• 页码：1154-1164
• 全文大小：667K
• ISSN：1520-510X

文摘

A bis-hydroxo-bridged dinuclear Co^III-pyridylmethylamine complex (1) was synthesized and the crystal structure was determined by X-ray crystallography. Complex 1 acts as a homogeneous catalyst for visible-light-driven water oxidation by persulfate (S₂O₈^2–) as an oxidant with [Ru^II(bpy)₃]²⁺ (bpy = 2,2′-bipyridine) as a photosensitizer affording a high quantum yield (44%) with a large turnover number (TON = 742) for O₂ formation without forming catalytically active Co-oxide (CoO_x) nanoparticles. In the water-oxidation process, complex 1 undergoes proton-coupled electron-transfer (PCET) oxidation as a rate-determining step to form a putative dinuclear bis-μ-oxyl Co^III complex (2), which has been suggested by DFT calculations. Catalytic water oxidation by 1 using [Ru^III(bpy)₃]³⁺ as an oxidant in a H₂¹⁶O and H₂¹⁸O mixture was examined to reveal an intramolecular O–O bond formation in the two-electron-oxidized bis-μ-oxyl intermediate, prior to the O₂ evolution.