Synthesis and photophysical properties of quinoxaline-based blue aggregation-induced emission molecules

A series of quinoxaline-based compounds 1-4 have been synthesized by a palladium-catalyzed cross-coupling reaction and their photophysical properties have been extensively studied. Compounds 1-4 show deep blue light emission both in solution (lambda(em) <= 425 nm, Commission Internationale de L'Eclairage y (CIEy) <= 0.03) and in the solid state. Moreover, compounds 1-3 show a non-typical aggregation-induced enhanced emission (AIEE), which would be effective deep blue light-emitting materials. The DFT calculation indicated that the HOMO energy levels of compounds 1-3 are distributed throughout the molecule, and the LUMO energy levels are mainly concentrated on the quinoxaline group. However, the HOMO of compound 4 is mainly on the benzene ring at 2,3 position, and the LUMO is distributed both of the quinoxaline and the benzaldehyde group at the 6,7 position.