Donor and acceptor engineering for BINOL based AIEgens with enhanced fluorescence performance

Organic AIEgens have been widely applied in multiple areas. However, most of them were designed based on AIE core skeletons. It's still a formidable challenge to design efficient AIEgens from simple ACQ fluorophores. Herein, we provided and perfected a strategy for developing new AIEgens by donor and acceptor engineering. By this strategy, we have synthesized two series of organic AIEgens based on a core skeleton of BINOL. The effect of steric hindrance and the electronic effect of the substituent on the optical properties have been discussed. Notably, the introduction of a donor and acceptor with large steric hindrance achieved fluorophores 2b and 2c with efficient solid emission, a high AIE effect factor and a large Stokes shift; typically, 2b exhibited a good performance in bioimaging. Meanwhile, the effect of the balance between the electron donor and acceptor should be paid attention. This AIEgen design strategy serves as new inspiration for turning ACQ skeletons to AIEgens.