Phenothiazine derivatives based on double benzylidene ketone structure: Application to red light photopolymerization

Two novel phenothiazine derivatives PTZs (PTZ-H and PTZ-C) with D-A configuration based on double benzylidene ketone structure were synthesized and showed good charge transfer capability. The absorption wavelength of PTZ-C formed by introducing aryl groups to both sides of PTZ-H can reach more than 620 nm. In photopolymerization, PTZ-C performed better than PTZ-H as a photosensitizer to sensitize iodonium salt (ONI) to initiate free radical photopolymerization (FRP) and cationic photopolymerization (CP) under 532 and 620 nm LED light source. The photochemical reaction processes between PTZs and ONI were studied by means of steady-state photolysis, UV–vis absorption, cyclic voltammetry (CV), and fluorescence quenching experiments.