Phosphinylation/cyclization of propynolaldehydes to isobenzo-furanylic phosphine oxides displaying AIE properties

Investigating organic reactions to synthesize novel molecules that exhibit aggregation-induced emission (AIE) characteristics is becoming a research hotspot. Herein, we develop a one-pot phosphinylation/cyclization reaction between propynolaldehydes and diarylphosphine oxides to generate isobenzofuran-substituted phosphine oxides (IBFPOs) displaying AIE properties. Such a reaction possesses benefits such as metal-free synthesis, simple operation and wide substrate applicability. Further structural modifications of the products have been implemented through the palladium-catalyzed Sonogashira reaction, Ullmann coupling and Diels-Alder addition. Furthermore, these AIE luminogens (AIEgens), which have satisfactory quantum yields and tunable emission covering the entire visible region, can be employed for the cell imaging of lipid droplets in HeLa cells. Notably, quantitative evaluation of the phototherapy effect demonstrates that one of these presented AIEgens, namely IBFPO-3j, displays high type-I reactive oxygen species (ROS) generation efficiency, enabling its effective application in photodynamic therapy in a hypoxic environment.