Blue light-driven selective aerobic oxidation of amines by benzothiadiazole metal–organic framework photocatalysis

Abstract

Metal–organic frameworks (MOFs), which can be precisely tailored through inorganic metal nodes and their organic ligands, present a promising avenue for developing high-performance photocatalysts. Herein, two isostructural MOFs, UiO-68-NH₂ and UiO-68-BT, are synthesized using Zr₆O₄(OH)₄¹²⁺ clusters and linear dicarboxylic ligands. Adjusting the electron-withdrawing effect of the ligands from 2′-amino-[1,1′:4′,1″-terphenyl]-4,4″-dicarboxylic acid to 4,4′-(benzo[c][1,2,5]-thiadiazole-4,7-diyl)dibenzoic acid results in MOFs with varied optoelectronic properties. UiO-68-NH₂ shows no performance, whereas UiO-68-BT stands out for its exceptional photocatalytic performance in blue light-driven selective aerobic oxidation of benzylamine, achieving a conversion of 93% and selectivity of 99% in 45 min. Recycling tests further confirm the stability and reusability of UiO-68-BT, implying its potential as a durable photocatalyst. A variety of amines are converted swiftly with molecular oxygen, and the selective generation of imines is carried out by superoxide radical anion. This research highlights the benefits of modulating the electronic effect of organic ligands of MOF photocatalysts, opening a new avenue for aerobic oxidation reactions.