Structural Engineering in Polyoxovanadate–Organic Cages toward Photocatalytic Synthesis of Benzimidazoles

Abstract

Photocatalytic fabrication of fine chemicals provides a sustainable method of development for the pharmaceutical industry. At present, optimizing the performance of photocatalysts via precise structural engineering at the atomic level is of the utmost importance. To unleash the potential of structurally editable polyoxovanadate–organic cages (POV-MOCs) as photocatalytic materials, herein, a family of five POV-MOCs were scaffolded by a cross combination of {V₆X} (X = SO₄^2–, PhPO₃^2–, and NH₂PhAsO₃^2–) vertices and benzo-2,1,3-thiadiazole-functionalized carboxylate linkers. Along with the structural evolution from capsule to cuboid-type topology as well as the heterogroup modification of the vertex, the photophysical properties of POV-MOCs could be regulated precisely. The structurally optimized POV-MOCs demonstrated prominent photocatalytic activity in the oxidative synthesis of benzimidazoles, which are medicinally important. Thanks to the teamwork of experimental and theoretical studies, a possible reaction mechanism that involves O₂^•– has been proposed and validated. The unveiled structure–function relationship provides an effective route to customize POV-MOC-based photocatalysts for a broader range of sustainable applications.