An Imidazo[1, 2-a]Pyridine Based Fluorescent Probe for the Continuous "on-off-on" Detection of Fe 3+ and F

An "on-off-on" fluorescent probe LK was synthesized from 2-benzoylpyridine and o-vanillin, which could sequentially detect Fe and F in DMSO/H O solutions (v/v = 1/1, HEPES buffer, 1.0 mM, pH 7.0) with large Stokes shift (178 nm). LK exhibited not only high selectivity and sensitivity towards Fe and F , but also strong anti-interference ability to other ions. LK was coordinated with Fe at a ratio of 2:1, with a binding constant (K ) of 1.3 × 10 M . The detection limits for Fe and F were 6.9 × 10 M and 3.0 × 10 M, respectively. Due to its excellent sensing performance, LK was successfully applied in actual water samples and test papers for the detection of Fe and F .