The synthesis of novel, visible-wavelength oxidizable polymerization sensitizers based on the 5,12-dihydroquinoxalino[2,3-b]pyridopyrazine skeleton

Novel dyes based on the 5,12-dihydroquinoxalino[2,3-b]pyridopyrazine skeleton were synthesized and subsequently characterized using 1H NMR. Their electrochemical and spectral properties, such as absorption and emission spectra, quantum yield of fluorescence, and quantum yield of singlet oxygen generation, were also measured. The dyes were useful as photoinitiators for sensitizing compounds to photooxidation. Photoredox pairs comprising dyes and onium salts were found to be effective visible-wavelength initiators of free radical or cationic polymerization.