Carbonized Polymer Dots-Promoted Photocatalytic Activation of Molecular Oxygen for Efficient and Selective Oxidation of Thioethers to Sulfoxides

Sulfoxides are essential in pharmaceuticals and chemicals, yet traditional thioether oxidation struggles with selectivity and sustainability. This study introduces carbonized polymer dots (CPDs) as effective photocatalysts for ecofriendly thioether to sulfoxide oxidation, using water and ethanol to enhance reaction selectivity and efficiency under 455 nm blue light. These catalysts not only show remarkable efficacy under mild conditions but also display high selectivity for sulfoxide formation, proving versatile across a broad range of substrates. We further elucidated the catalytic mechanism, confirming the predominant roles of singlet oxygen and superoxide anions through both spectroscopic evidence and quenching experiments. The method extends to the synthesis of pharmaceuticals such as oxfendazole, albendazole sulfoxide, and sulindac, highlighting its practical utility. Overall, our findings present a sustainable and efficient avenue for sulfoxide synthesis, thereby broadening the practical utility of CPDs in photocatalytic transformations.