Polarization-driven reactive oxygen species modulation in asymmetric π-conjugated polymers for efficient photocatalytic thioether to sulfoxide conversion

Selective aerobic oxidation of thioethers to sulfoxides over efficient visible-light photocatalysts is an essential yet highly challenging transformation in catalytic oxidation chemistry. Herein, we introduce an asymmetric perylene diimide–based π-conjugated polymer (BCPDI) with intrinsic polarization that enhances charge transport and tunes the local microenvironment to efficiently regulate reactive oxygen species(ROS) generation for efficient thioether oxidation. DFT calculations show that symmetry breaking separates frontier orbitals and creates an internal electrostatic potential gradient, thereby accelerating charge carrier transport and driving O 2 reduction to generate superoxide radicals (·O 2 − ), whereas symmetric analogs produce only singlet oxygen ( 1 O 2 ) via energy transfer. Driven by the synergistic effect of electron and energy transfer pathways, BCPDI achieved over 99% conversion and selectivity for thioether oxidation under ambient conditions, outperforming most recently reported materials. In addition, BCPDI also exhibits a superior catalytic activity for thioether oxidation (e.g., aromatic thioethers, aliphatic sulfide, and Mustard Gas sulfide). This study provides a new approach for the design of catalysts for photocatalytic aerobic oxidation of thioethers and deepens the understanding of thioether activation mechanisms mediated by photogenerated charge carriers and reactive oxygen species.