Supramolecular packing dominant photocatalytic oxidation and anticancer performance of PDI

Abstract The development of organic supramolecular photocatalytic materials requires a deeper understanding of the structure-activity relationship. Herein, the effects of H/J-type stacking on the photocatalytic mechanism and activity of PDI have been investigated. As a face-to-face arrangement, H-aggregates have higher π-electron conjugation and show more semiconductor characteristics, which results in higher carrier separation and migration efficiency under irradiation. Whereas, J-aggregates exhibit more molecular properties due to its low π-electron conjugation caused by head-to-tail stacking mode. As a result, H-aggregated PDI mainly forms superoxide radicals ( O 2 − ) and holes (h + ) through electron-transfer (ET). In contrast, J-aggregated PDI mainly generates singlet oxygen species ( 1 O 2 ) via energy-transfer (EnT). Benefit from the stronger oxidizability of O 2 − and h + , H-aggregated PDI shows higher photocatalytic activity for small molecule degradation and oxygen evolution under visible light. Whereas, J-aggregated PDI exhibits potential application in photocatalytic anti-cancer treatment owing to its high 1 O 2 quantum yields (0.66) under red light radiation. Our findings may provide a guidance for the development of supramolecular organic photocatalytic materials.