Otsuka Hiroki, Kobayashi Atsushi, Yoshida Masaki, Kato Masako
Department of Chemistry, Faculty of Science, Hokkaido University, North-10 West-8, Kita-ku, Sapporo 060-0810, Japan.
Department of Applied Chemistry for Environment, School of Biological and Environmental Sciences, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
Dalton Trans. 2021 Nov 16;50(44):16233-16241. doi: 10.1039/d1dt02824c.
We synthesized new oxygen-evolving molecular Ru(II) catalysts with one or two carbazole moieties on the axial pyridyl ligands, namely [Ru(bda)(cbz-py)(py)] and [Ru(bda)(cbz-py)] [C1 and C2; bdaH = 2,2'-bipyridyl-6,6'-dicarboxylic acid, py = pyridine, and cbz-py = 9-(pyridin-4-yl)-9-carbazole] to investigate the effect of cbz modification on the photophysical and catalytic properties of the well-known molecular catalyst [Ru(bda)(py)] (C0). The initial oxygen-evolving catalytic activities of C1 and C2 were higher than that of C0 in both a chemical reaction driven by the strong oxidant (NH)[Ce(NO)] (CAN = ceric ammonium nitrate) and photochemical oxidation using a [Ru(bpy)] (bpy = 2,2'-bipyridine) photosensitizer with NaSO as the sacrificial oxidant. The higher activities were ascribed to the electron-withdrawing cbz groups, which promoted the radical coupling reaction to form a Ru-O-O-Ru species. A unique oxygen-evolution rate change behaviour was observed for both C1 and C2 in the presence of a large excess of CAN, suggesting the competitive oxidation of the cbz moiety during the chemical oxygen evolution reaction. This work suggests that the cbz modification of an oxygen evolution molecular catalyst is a promising approach for integrating the hole accumulator near the oxygen evolution catalytic centre.
我们合成了新型析氧分子钌（II）催化剂，其轴向吡啶基配体上带有一个或两个咔唑部分，即[Ru(bda)(cbz-py)(py)]和[Ru(bda)(cbz-py)] [C1和C2；bdaH = 2,2'-联吡啶-6,6'-二羧酸，py = 吡啶，cbz-py = 9-(吡啶-4-基)-9-咔唑]，以研究咔唑修饰对著名分子催化剂[Ru(bda)(py)]（C0）的光物理和催化性能的影响。在由强氧化剂(NH)[Ce(NO)]（CAN = 硝酸铈铵）驱动的化学反应以及使用[Ru(bpy)]（bpy = 2,2'-联吡啶）光敏剂和NaSO作为牺牲氧化剂的光化学氧化反应中，C1和C2的初始析氧催化活性均高于C0。较高的活性归因于吸电子的咔唑基团，其促进了自由基偶联反应以形成Ru-O-O-Ru物种。在大量过量的CAN存在下，观察到C1和C2均具有独特的析氧速率变化行为，这表明在化学析氧反应过程中咔唑部分发生了竞争性氧化。这项工作表明，对析氧分子催化剂进行咔唑修饰是在析氧催化中心附近整合空穴累积器的一种有前景的方法。
