AIE-ESIPT based colorimetric and “OFF-ON-OFF” fluorescence Schiff base sensor for visual and fluorescent determination of Cu2+ in an aqueous media

Abstract A novel benzimidazole-derived active Schiff base fluorescence probe 1-[[(1H-1,3-benzodiazol-2-yl)imino]methyl]naphthalen-2-ol (HBN) was designed, synthesized and characterized with high selectivity toward Cu2+ based on “OFF-ON-OFF” aggregation-induced emission (AIE) fluorescence strategy. HBN exhibited strong fluorescence enhancement in water. It was used for the selective determination of Cu2+ in aqueous solution, which displayed a significant fluorescence quenching in CH3CH2OH-PBS (v/v = 1:1, pH = 7.0) mixed solution. HBN displayed a good linear relationship with Cu2+ in the range of 0.16–250 μM and the limit of detection was 8.14 × 10−8 M. The binding stoichiometry of HBN with Cu2+ was 2:1 calculating by Job’s plot analysis, FT-IR and density functional theory. Ultimately, in order to verify the paracticability of the synthesized probe, HBN was applied to the detection of Cu2+ in tap water, traditional Chinese medicinal materials and marine products. The above description implied the good application prospect of detecting Cu2+ in the complicated environment, and provided a reference for the identification of metal ions.