Structure-Activity and Stability Relationships for Cobalt Polypyridyl-Based Hydrogen-Evolving Catalysts in Water
作者:Stephan Schnidrig、Cyril Bachmann、Peter Müller、Nicola Weder、Bernhard Spingler、Evelyne Joliat-Wick、Mathias Mosberger、Johannes Windisch、Roger Alberto、Benjamin Probst
DOI:10.1002/cssc.201701511
日期:2017.11.23
photocatalysis. In the acidic branch, a proton‐coupled electron transfer, assigned to formation of CoIII−H, is found upon reduction of CoII, in line with a pKa(CoIII−H) of approximately 7.25. Subsequent reduction (−0.94 V vs. NHE) and protonation close the catalytic cycle. Methoxy substitution on the bipyridyl scaffold results in the expected cathodic shift of the reduction, but fails to change the pKa(CoIII−H)
在水中的光催化运行中,对一系列八种新的和三种已知的基于聚吡啶基钴的放氢催化剂(HEC)进行了测试。就稳定性和速率而言,亚甲基桥双联吡啶是首选的支架。对于四齿甲醇桥联的双吡啶基-联吡啶基配合物[Co II Br(tpy)] Br的钴配合物,可以通过结合电化学,光谱学和光催化获得详细的机理图。在酸性分支,一个质子偶合的电子转移,被分配给形成的Co III -H,被还原后的Co发现II,符合AP ķ一个(钴III-H)约为7.25。随后的还原(相对于NHE为-0.94 V)和质子化关闭了催化循环。在联吡啶骨架上的甲氧基取代导致预期的还原反应的阴极移位,但是不能改变p K a(Co III -H)。鉴于这种假定的机理,对基准测试的结果进行了分析,并对新一代催化剂的设计标准进行了展望。