Regulation of the bi-color fluorescence changes of AIE supramolecular self-assembly gels by interaction with Al3+ and energy transfer

Supramolecular fluorescent materials have attracted considerable attention in recent years since they endow specific and unique properties to materials. Nevertheless, the utilization of photoresponsive characteristics to modulate their fluorescence emission behaviors and functions remain rarely explored. Here a facile fabrication strategy for producing dual-emissive materials based on supramolecular gels is proposed. A bi-acylhydrazone supramolecular gelator BD was designed and synthesized by a Schiff base reaction. Interestingly, the gelator BD could self-assemble into the stable supramolecular gel BDG with a strong aggregation-induced emission (AIE) in DMF–H2O binary solutions via π–π stacking interactions. On the one hand, the BDG could selectively identify Al3+ in the gel state. Upon addition of Al3+, AIE BDG showed an obvious blue-shift (85 nm, from yellow–green to sky-blue). On the other hand, artificial light-harvesting systems were successfully fabricated in a gel environment based on the supramolecular strategy. In these systems, efficient energy transfer occurs between the BD assembly and the loaded acceptors. For instance, the transition from yellow–green to red light could be accomplished in the BDG/SR 101 system. Based on these, the manipulation of bi-color fluorescence emission was realized by interaction with Al3+ and energy transfer.