Motz Rachel N, Lopato Eric M, Connell Timothy U, Bernhard Stefan
Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States.
Inorg Chem. 2021 Jan 18;60(2):774-781. doi: 10.1021/acs.inorgchem.0c02790. Epub 2021 Jan 7.
Noble-metal photosensitizers and water reduction co-catalysts (WRCs) still present the highest activity in homogeneous photocatalytic hydrogen production. The search for earth-abundant alternatives is usually limited by the time required to screen new catalyst combinations; however, here, we utilize newly designed and developed high-throughput photoreactors for the parallel synthesis of novel WRCs and colorimetric screening of hydrogen evolution. This unique approach allowed rapid optimization of photocatalytic water reduction using the organic photosensitizer Eosin Y and the archetypal cobaloxime WRC [Co()pyCl], where is dimethylglyoxime and py is pyridine. Subsequent combinatorial synthesis generated 646 unique cobalt complexes of the type [Co()pyCl], where is a bidentate ligand, that identified promising new WRC candidates for hydrogen production. Density functional theory (DFT) calculations performed on such cobaloxime derivative complexes demonstrated that reactivity depends on hydride affinity. Alkyl-substituted glyoximes were necessary for hydrogen production and showed increased activity when paired with ligands containing strong hydrogen-bond donors.
贵金属光敏剂和水还原助催化剂（WRCs）在均相光催化产氢中仍具有最高的活性。寻找储量丰富的替代物通常受到筛选新催化剂组合所需时间的限制；然而，在此我们利用新设计和开发的高通量光反应器，用于新型WRCs的平行合成和析氢的比色筛选。这种独特的方法能够使用有机光敏剂曙红Y和典型的钴肟WRC [Co()pyCl]（其中为二甲基乙二肟，py为吡啶）对光催化水还原进行快速优化。随后的组合合成产生了646种[Co()pyCl]类型的独特钴配合物，其中为双齿配体，这些配合物确定了有前景的产氢新WRC候选物。对这类钴肟衍生物配合物进行的密度泛函理论（DFT）计算表明，反应活性取决于氢化物亲和力。烷基取代的乙二肟对于产氢是必需的，并且当与含有强氢键供体的配体配对时显示出更高的活性。
