Molecular engineering to achieve AIE-active photosensitizers with NIR emission and rapid ROS generation efficiency

Abstract

Near-infrared (NIR) photosensitizers with rapid reactive oxygen species (ROS) production ability are in great demand owing to their promising performance toward boosting photodynamic therapy (PDT) and deep-tissue imaging, but molecular design guidelines for efficient photosensitizers are rarely elucidated. Herein, three AIEgens named DBP, TBP, and TBP-SO₃ are designed and synthesized by precise donor–acceptor (D–A) molecular engineering to deeply understand the structure–property–application relationships. All the compounds exhibit AIE characteristics with strong long-wavelength emission in the aggregated state and are capable of efficiently producing ROS under white light irradiation. By controlling the ability of the D–A units, TBP-SO₃ realizes NIR emission and more rapid ROS generation ability due to the promoted intersystem crossing processes compared with those of DBP and TBP. In addition, NIR-emitting TBP-SO₃ is capable of specific endoplasmic reticulum targeting and excellent PDT treatment ability of cancer cells and bacteria. This successful example of molecular engineering paves a valuable way for developing advanced PSs with AIE properties, efficient ROS generation ability, and intense emission for fluorescence imaging PDT.