Photo-hydrogen-evolving molecular catalysts consisting of polypyridyl ruthenium(II) photosensitizers and platinum(II) catalysts: insights into the reaction mechanism.
Photo-hydrogen-evolving molecular catalysts consisting of polypyridyl ruthenium(II) photosensitizers and platinum(II) catalysts: insights into the reaction mechanism.
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DOI：
10.1002/asia.201000083
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发表时间：
2010-08
期刊：
影响因子：
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通讯作者：
Hironobu Ozawa;Masayuki Kobayashi;Bijitha Balan;Shigeyuki Masaoka;K. Sakai
中科院分区：
文献类型：
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作者：
Hironobu Ozawa;Masayuki Kobayashi;Bijitha Balan;Shigeyuki Masaoka;K. Sakai
研究了第一种光生放氢分子催化剂[Ru（bpy）（2）（5-amino-phen）]（2+）与[PtCl（2）（4，4 '-dicarboxy-bpy）]（bpy = 2，2'-bipyridine，phen = 1，10-phen）的偶联反应驱动水光生放氢的机理.发现H（2）的释放速率与EDTA（乙二胺四乙酸二钠盐，牺牲电子供体）的浓度有关，这表明EDTA（pH 5）的双阳离子1和双阴离子形式之间的离子对形成是导致H（2）形成的关键步骤。1和乙二胺的2：1偶联产物（即，发现{Ru（II）（2）Pt（II）（2）}配合物2）显示出比1显著更高的光放氢（PHE）活性，这揭示了我们先前研究中提出的双分子活化的有效性。2的PHE活性与2的浓度呈线性关系，表明分子内和分子间的H2生成竞争.通过DFT计算表征了分子轨道图、构象特征和PtH（水或乙酸）氢键.
The mechanism of photoinduced hydrogen evolution from water driven by the first photo-hydrogen-evolving molecular catalyst (1), given by a coupling of [Ru(bpy)(2)(5-amino-phen)](2+) and [PtCl(2)(4,4'-dicarboxy-bpy)] (bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline), was investigated in detail. The H(2) evolution rate was found to obey Michaelis-Menten enzymatic kinetics with regard to the concentration of EDTA (ethylenediamine tetra-acetic acid disodium salt, sacrificial electron donor), which indicates that an ion-pair formation between the dicationic 1 and the dianionic form of EDTA (pH 5) is a key step leading to H(2) formation. A 2:1 coupling product of 1 and ethylenediamine (i.e., a {Ru(II) (2)Pt(II) (2)} complex 2) was found to show significantly higher photo-hydrogen-evolving (PHE) activity than 1, which revealed the validity of the bimolecular activation proposed in our previous study. The PHE activity of 2 was also observed to be linear to the concentration of 2, which indicates that H(2) formation through the intermolecular path competes with the intramolecular path. Molecular orbital diagrams, conformational features, and PtH(water or acetic acid) hydrogen bonds were characterized by DFT calculations.