Cooperative effects in homogenous water oxidation catalysis by mononuclear ruthenium complexes.
Cooperative effects in homogenous water oxidation catalysis by mononuclear ruthenium complexes.
复制标题
DOI：
10.1039/c4dt00629a
复制
发表时间：
2014-04
影响因子：
4
通讯作者：
Yanyan Mulyana;F. Keene;L. Spiccia
中科院分区：
文献类型：
--
作者：
Yanyan Mulyana;F. Keene;L. Spiccia
在两种氧化还原介质[Ru(bipy)3](2+)(3)和[Ru(terpy)(bipy)Cl](+)(1)和[Ru(terpy)(Me2bipy)Cl](+) (2) (2) (2)](2+) (4) （phen = 1,10-菲罗啉）的影响下，研究了[Ru(terpy)(bipy)Cl](+)(1)和[Ru(terpy)(Me2bipy)Cl](+)(2)(2)(2)(2))(2)(2))(2)(2))(2)(2))(2)(2))(2)(2))(2))(2)(2))(2))(2)(2))(2))(2)(2))(2))(2))(2))(2))(2))(2))（2))(1)）的催化氧化反应。析氧实验表明，2-4和2-3的混合物比单独使用催化剂2产生更多的分子氧。相反，介质4和催化剂1的组合导致1的催化性能较低。对四种等效Ce（4+）和2在261nm处引起的紫外跃迁强度的时间变化的测量揭示了三个不同的区域，表明对应于逐步过程：(i) [Ru(IV)=O]（2+）→[Ru(V)=O](3+)；（ii） [Ru(V)=O]（3+）→[Ru(III)-(OOH)](2+)；和(iii)[俄文(iii) -(哦)](2 +)→[俄文(II)这里](2 +)。用四种等量Ce（4+）对1-4和2-4混合物进行紫外可见分光光度实验，结果表明，2-4中[Ru(phen)2(Me2bipy)]（3+）→[Ru(phen)2(Me2bipy)]（2+）的还原速率比1-4组合更快。催化剂和混合物的循环伏安测量数据表明，介质3和4的Ru(II)/Ru（III）氧化还原过程电位与催化剂2的[Ru(IV)=O](2+)/[Ru(V)=O]（3+）预测电位吻合。相比之下，催化剂1的[Ru(IV)=O](2+)/[Ru(V)=O]（3+）过程的电位高于催化剂4的Ru(II)/Ru（III）氧化还原过程。光谱和电化学实验都证明了介体和催化剂之间的相互作用是催化活性的重要决定因素。
The homogenous water oxidation catalysis by [Ru(terpy)(bipy)Cl](+) (1) and [Ru(terpy)(Me2bipy)Cl](+) (2) (terpy = 2,2':6',2''-terpyridine, bipy = 2,2'-bipyridine, Me2bipy = 4,4'-dimethyl-2,2'-bipyridine) under the influence of two redox mediators [Ru(bipy)3](2+) (3) and [Ru(phen)2(Me2bipy)](2+) (4) (phen = 1,10-phenanthroline) was investigated using Ce(4+) as sacrificial oxidant. Oxygen evolution experiments revealed that mixtures of both 2-4 and 2-3 produced more molecular oxygen than catalyst 2 alone. In contrast, the combination of mediator 4 and catalyst 1 resulted in a lower catalytic performance of 1. Measurements of the temporal change in the intensity of a UV transition at 261 nm caused by the addition of four equivalents of Ce(4+) to 2 revealed three distinctive regions-suggested to correspond to the stepwise processes: (i) [Ru(IV)=O](2+) → [Ru(V)=O](3+); (ii) [Ru(V)=O](3+) → [Ru(III)-(OOH)](2+); and (iii) [Ru(III)-(OOH)](2+) → [Ru(II)-OH2](2+). UV-Visible spectrophotometric experiments on the 1-4 and 2-4 mixtures, also carried out with four equivalents of Ce(4+), demonstrated a faster [Ru(phen)2(Me2bipy)](3+) → [Ru(phen)2(Me2bipy)](2+) reduction rate in 2-4 than that observed for the 1-4 combination. Cyclic voltammetry data measured for the catalysts and the mixtures revealed a coincidence in the potentials of the Ru(II)/Ru(III) redox process of mediators 3 and 4 and the predicted [Ru(IV)=O](2+)/[Ru(V)=O](3+) potential of catalyst 2. In contrast, the [Ru(IV)=O](2+)/[Ru(V)=O](3+) process for catalyst 1 was found to occur at a higher potential than the Ru(II)/Ru(III) redox process for 4. Both the spectroscopic and electrochemical experiments provide evidence that the interplay between the mediator and the catalyst is an important determinant of the catalytic activity.