Bimetallic synergy significantly enhances the photocatalytic performance of lanthanide porphyrin-based MOFs: Efficient photocatalytic oxidation of benzyl alcohol and benzylamine under mild conditions in air

Abstract

Metal-organic frameworks as photocatalysts for the conversion of light energy into chemical energy applied to organic conversion is an efficient and sustainable strategy. Lanthanide organometallic frameworks perform poorly in photocatalytic organic reactions owing to their high electron and hole complexation rates. Inspired by the synergistic effect of biomacromolecule porphyrin as a photosensitizer with bimetallic pairs that can boost electron transport efficiency. We synthesized a series of lanthanide porphyrin mechanism MOFs (Nd PMOFs, Co–Nd PMOFs, Ni–Nd PMOFs). These PMOFs are endowed with a novel three-dimensional structure. It is noteworthy that Ni in the middle of the porphyrin ring enhances the photocatalytic performance of Ni–Nd PMOFs. The reasons can be attributed to the introduced Ni and the coordinated Nd elements, which interact synergistically with the porphyrin skeleton. This interaction results in a good photoresponse and promotes an efficient separation of photogenerated electrons and holes. The photocatalytic performance of Ni–Nd PMOFs was tested under mild conditions (12 W visible light, air) using the photocatalytic oxidation of benzyl alcohol and the oxidative coupling of benzylamine as model reactions. The conversion rate for benzyl alcohol was 90 % with a selectivity 94 %, and the conversion rate for benzylamine was 85 % with a selectivity 83 %. The photocatalytic oxidation performance of Ni–Nd PMOFs has been found to be excellent for a wide range of reactions and substrates, indicating that it is a promising photocatalyst. To some extent, the presentation of this work expands the possibilities of lanthanide metal frameworks for photocatalytic organic transformations and sheds new light on the multidirectional applications of lanthanide metal–organic frameworks.