Constructing a Polyoxometalate-Based Metal–Organic Framework for Photocatalytic Oxidation of Thioethers to Sulfoxides Utilizing In Situ-Generated Superoxide Radicals

Abstract

Developing new photocatalysts for the selective oxidation of thioethers to high-value-added sulfoxides under low-oxygen mild conditions is a promising but challenging strategy. Here, a new polyoxometalate-based metal–organic framework (POMOF), CoBW₁₂–TPT, was successfully synthesized, wherein continuous π···π stacking interactions and direct coordination bonds not only strengthen the framework's stability but also accelerate electron transfer. A series of experiments and theoretical studies, including control experiments, kinetic studies, electrochemical spectroscopic analyses, and electron paramagnetic resonance, revealed the synergistic catalytic effect among Co(II) metal centers, BW₁₂O₄₀^5–, and the photosensitizer TPT. CoBW₁₂–TPT was applied in the photocatalytic oxidation of thioethers to sulfoxides. Under irradiation, the photoinduced electron transfer of POMOF leads to the generation of superoxide radicals from O₂, which controls the selective generation of sulfoxide compounds in the photocatalytic desulfurization reaction and shows good activity. In particular, it can be applied to the construction of some drug molecules such as Modafinil and Albendazole Oxide.