A near-infrared fluorescent probe for H2S based on tandem reaction to construct iminocoumarin-benzothiazole and its application in food, water, living cells.

With the merits of non-destructive, high penetration ability and minimizing autofluorescence, near-infrared (NIR) fluorescent probes have attracted much attention. In this paper, a NIR emission fluorescent turn-on probe THQ-L for H2S was synthesized by the knoevenagel condensation between tetrahydroquinoxaline-6- formaldehyde derivative and 2-benzothiazoleacetonitrile. THQ-L can recognize H2S through tandem reaction triggered by HS- to construct 1,4-diethylpiperazine-modified iminocoumarin-benzothiazole, which produces a strong red fluorescent signal. THQ-L displayed an excellent selectivity toward H2S, a large stokes shift (126 nm), a high signal-to-noise ratio (200-fold), the detection limits of 38.3 nM in PBS (10 mM, pH 7.4, 30% THF). The application study indicates that THQ-L can sensitively detect H2S in red wine, natural waters, living cells and can be prepared for a test paper strip for the qualitative detection of H2S.