Rational Design of AIE Photosensitizers with Full-Visible Color Emission and Efficient ROS Generation

Organic photosensitizers (PSs) with aggregation-induced emission (AIE) characteristics have shown several advantages in photodynamic therapy (PDT). However, how to design PSs with the required optical and biological properties is a formidable challenge. In this work, a series of AIE active pyridine- and pyridinium-functionalized carbazole with different substituents are designed and synthesized. Compared to other analogs, BK-Pys-BP containing benzophenone moiety on the pyridinium unit produces reactive oxygen species (ROS) efficiently in the presence of light due to its large spin-orbit coupling constant to promote efficient intersystem crossing. Based on its structure, three molecules with enhanced donor-acceptor strength and conjugation are further investigated to realize emission covering the whole visible region. The cationic nature and excellent ROS generation ability of benzophenone-containing AIE photosensitizers allows for specific imaging of mitochondria, killing cancer cells, and as a singlet oxygen donor to catalyze the formation of endoperoxides. Thus, the present work presents an effective strategy for creating AIE photosensitizers with efficient ROS generation for wide biological applications. A molecular design concept to enhance reactive oxygen species (ROS) generation is presented, and full-wavelength visible light materials are synthesized and applied to photodynamic therapy and catalysis of endoperoxide formation. This work provides insight into improving the ROS efficiency of photosensitizers and controlling the release of 1O2 to achieve afterglow therapy.image