AIE gels based on Schiff base with stimuli-responsive fluorescence switching behaviors as chemosensors

Based on Schiff base unit with/without a perfluoroalkyl group, novel multi-functional compounds 1 and 2 were proven to be able to form gels with different solvents. The difference in the molecular structure of compounds 1 and 2 was the presence of a perfluoroalkyl chain. The self-assembly pattern was studied by the employment of rheological analysis, UV-vis absorption, fluorescence spectrum, field emission scanning electron microscopy (FESEM), fourier transforms infrared (FTIR) spectra, and X-ray powder diffraction (XRD). The gelation behaviors showed a sensitive and selective “turn-off” fluorescence response with Cu2+. Due to the protonation or deprotonation of compounds 1 and 2 with trifluoroacetic acid (TFA) or triethylamine (TEA), the xerogel films which were prepared from DMSO:H2O (9:1, v/v) at 5 wt% presented the emission quenching and recovery upon TFA and TEA vapors. In this sense, the work will open up a novel pathway to detect Cu2+, TFA, and TEA in the environment, using stimuli-responsive fluorescent materials with aggregation-induced emission (AIE) effect.