A facile synthesized benzophenone Schiff-base ligand as efficient type II visible light photoinitiator

Abstract Prolongation of the absorption wavelength of photoinitiator is very important issue but often suffered from tedious synthesis and purification procedures. In this work, by one spot Schiff base condensation of 4-anmino-benzophenone and 4-(dimethylamino)-2-hydroxybenzaldehyde, a benzophenone incorporated Schiff base ligand BPN was prepared. The structure of BPN was well characterized by spectroscopy technology. BPN shows strong absorption among the wavelength of 400 ∼ 500 nm. The initiation efficiency of BPN toward an acrylate monomer under 405/460 nm LED was evaluated by real-time FT-IR technology. The photoreaction between BPN and co-initiator was studied by steady state photolysis, fluorescence quenching, electron spin resonance spin trapping, nano-second transient absorption and cyclic voltammetry techniques. The results showed that BPN had strong interaction with amine co-initiator. This work proves that BPN is an excellent visible light photoinitiator and Schiff base condensation is a reliable way to design novel photoinitiator.