Curcuminoid-Based Difluoroboron Dyes as High-Performance Photosensitizers in Long-Wavelength (Yellow and Red) Cationic Photopolymerization.

Difluoroboron β-diketonate dyes are reported to exhibit excellent photophysical properties (e.g., broad absorption and large extinction coefficients) and have the potential to act as high-performance photosensitizers in cationic photopolymerization (CP). In this study, four curcuminoid-based difluoroboron dyes (BF Curs) are prepared. Their ability to initiate the CP of epoxides or vinyl ethers in combination with an iodonium salt under yellow and red LEDs is investigated. Some of the BF Curs-based photoinitiating systems exhibit much higher efficiencies than the reported anthraquinone derivative Oil Blue N (OBN). The molecular structure of BF Curs is found to play a critical role in the photoinitiating efficiencies of cationic polymerization.