Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, Mail Code 0358, La Jolla, California 92093-0358, United States.
Inorg Chem. 2020 Dec 7;59(23):16872-16881. doi: 10.1021/acs.inorgchem.0c01669. Epub 2020 Nov 16.
A new synthetic route to complexes of the type Ni(PN) with highly functionalized phosphine substituents and the investigation of immobilization effects on these catalysts is reported. Ni(PN) complexes have been extensively studied as homogeneous and surface-attached molecular electrocatalysts for the hydrogen evolution reaction (HER). A synthesis based on postsynthetic modification of PN was developed and is described here. Phosphonate-modified ligands and their corresponding nickel complexes were isolated and characterized. Subsequent deprotection of the phosphonic ester derivatives provided the first Ni(PN) catalyst that can be covalently attached via pendent phosphonate groups to an electrode without involvement of the important pendent amine groups. Mesoporous TiO electrodes were surface modified by attachment of the new phosphonate functionalized Ni(PN) complexes, and these provided electrocatalytic materials that proved to be competent and stable for sustained HER in aqueous solution at mild pH and low overpotential. We directly compared the new ligand to a previously reported complex that utilized the amine moiety for surface attachment. Using HER as the benchmark reaction, the P-attached catalyst showed a marginally (9-14%) higher turnover number than its N-attached counterpart.
报道了一种新型合成路线，用于制备具有高度官能化膦取代基的 Ni(PN) 型配合物，并研究了这些催化剂的固定化效应。Ni(PN)配合物作为均相和表面附着的分子电催化剂，已被广泛研究用于析氢反应（HER）。本文开发了一种基于 PN 的后合成修饰的合成方法，并对其进行了描述。分离并表征了磷酸酯修饰的配体及其相应的镍配合物。随后对磷酸酯衍生物进行脱保护，得到了第一个可以通过侧基膦酸酯基团共价连接到电极上的 Ni(PN)催化剂，而不涉及重要的侧基胺基。介孔 TiO 电极通过附着新的磷酸酯功能化 Ni(PN)配合物进行表面修饰，这些配合物提供了电催化材料，在温和 pH 和低过电势下，在水溶液中持续进行 HER 时表现出良好的性能和稳定性。我们直接将新配体与之前报道的利用胺部分进行表面附着的配合物进行了比较。使用 HER 作为基准反应，P 附着的催化剂的周转数比 N 附着的催化剂高出 9-14%。
