A Thermoreversible and Proton-Induced Gel-Sol Phase Transition with Remarkable Fluorescence Variation

We have synthesized a novel highly fluorescent organogel system that uses a functional molecule with aggregation-induced enhanced emission (AIEE) properties. This AIEE organo gelator is more advanced than previously reported fluorescent gelators because it is practically nonfluorescent in the molecular sol state but highly fluorescent in the gel state, with a 170-fold enhancement in fluorescence intensity. This "functional fluorescent gelator" molecule forms strongly fluorescent and self-assembled gels in both nonpolar and polar protic solvents, even at low concentrations on the order of 0.2 wt %. These selfassembled organogels undergo completely thermoreversible and proton-induced gel-to-sol phase transitions with concomitant fluorescence intensity modulations. Moreover, we have demonstrated selective spatial patterning using the get-to-sol transition with this organogel system.