Ishizuka Tomoya, Watanabe Atsuko, Kotani Hiroaki, Hong Dachao, Satonaka Kenta, Wada Tohru, Shiota Yoshihito, Yoshizawa Kazunari, Ohara Kazuaki, Yamaguchi Kentaro, Kato Satoshi, Fukuzumi Shunichi, Kojima Takahiko
Department of Chemistry, Graduate School of Pure and Applied Sciences, University of Tsukuba , 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan.
Department of Chemistry, College of Science, Rikkyo University , 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan.
Inorg Chem. 2016 Feb 1;55(3):1154-64. doi: 10.1021/acs.inorgchem.5b02336. Epub 2016 Jan 21.
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 (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 as an oxidant in a H2(16)O and H2(18)O 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.
合成了一种双羟基桥联的双核钴（III）-吡啶甲基胺配合物（1），并通过X射线晶体学确定了其晶体结构。配合物1作为均相催化剂，以过硫酸盐（S2O8(2-)）为氧化剂，Ru(II)(bpy)3（bpy = 2,2'-联吡啶）为光敏剂，用于可见光驱动的水氧化反应，在不形成催化活性氧化钴（CoO(x)）纳米颗粒的情况下，O2生成具有高量子产率（44%）和大周转数（TON = 742）。在水氧化过程中，配合物1经历质子耦合电子转移（PCET）氧化作为速率决定步骤，形成一种假定的双核双μ-氧基钴（III）配合物（2），这已通过密度泛函理论计算得到证实。研究了在H2(16)O和H2(18)O混合物中，以Ru(III)(bpy)3为氧化剂，配合物1催化水氧化的过程，以揭示在O2释放之前，双电子氧化的双μ-氧基中间体中分子内O-O键的形成。
