Multicolor fluorescent switches in gel systems controlled by alkoxyl chain and solvent

Two simple molecules, 1 and 2 with D-pi-A structure and alkoxyl groups, respectively, were designed and synthesized. Both compounds can gelatinize THF-water and DMSO. And compound 2 forms gel in acetone by ultrasonic stimulus. Interestingly, these gels exhibit aggregation-induced emission (AIE) during the sol-gel phase transformation. Moreover, the molecular self-assembled and photophysical properties can be controlled by the number of the alkoxyl chains and the type of the solvents. For example, 1 has an identical packing model and fluorescent colour in THF-water and DMSO gels. Contrarily, the self-assembly of molecule 2 strongly depends on the solvent. Furthermore, the gel phases of 2 formed in three solvents possess different fluorescent colours. Such as, THF-water gel emits yellow fluorescence, acetone gel has orange emission and red fluorescence appears in DMSO.