Integrating Metal Complex Units and Redox Sites into Thorium-Based Metal-Organic Frameworks for Selective Photocatalytic Oxidation of Sulfides

A series of high-symmetry Th-6-metal-organic frameworks (MOFs) are constructed using various metal complex units and the thorium (Th) cluster, and then being applied as a well-defined catalyst model in the photocatalytic oxidation of methyl phenyl sulfide reactions. The integration of Th-6-MOFs by incorporating metal complex units and redox sites (Th-6 cluster and single-metal site) can effectively modulate the conversion rate and selectivity. Among them, Ni-PBA-Th-6 (PBA = 4-pyridin-4-yl benzoic acid) achieves up to & AP;99% conversion and & AP;97% selectivity for methyl phenyl sulfone. Experiments and theoretical calculations further elucidate that Th-6 cluster is the catalytic site for the oxidation of methyl phenyl sulfide to methyl phenyl sulfone, while Ni-PBA is the catalytic site for the reduction of hydrogen peroxide. This work sheds new insight into the structural design and photocatalytic application of more efficient thorium-based MOF catalysts.