Acylhydrazone functionalized naphthalene-based self-assembled supramolecular gels for efficient fluorescence detection of Fe³

A new gel factor (named N) has been successfully designed and synthesized, which contains the conventional fluorophore naphthalene with the acylhydrazone bond as the self-assembly site. It can be self-assembled into stable organogels (named ON) in dimethyl sulfoxide (DMSO) and water mixed medium (V : V = 4 : 1) with a critical gel temperature and concentration (55 °C and 10 mg mL^-1). Interestingly, under 365 nm UV light, the ON exhibits bright yellow Aggregation Induced Emission (AIE). The supramolecular organogel ON shows a fluorescent "OFF" response to the metal ions Fe³⁺, and the state of the gel ON remains constant before and after detection. Notably, the minimum detection limits (LODs) of the gel ON for Fe³⁺ are as low as 1.30 × 10^-7 M. The binding mechanism of supramolecular organogels (ON) to ions has been investigated through a series of characterizations. Meanwhile, the organogel sensor ON can also be used as an ion-responsive membrane for the detection of Fe³⁺ in the aqueous phase.