A high-performance colorimetric fluorescence sensor based on Michael addition reaction to detect HSO3− in real samples

Abstract Based on the Michael addition mechanism, a colorimetric fluorescence sensor (E)-2-(2-(9-benzyl-9H-carbazol-3-yl)vinyl)-3-methylbenzo[d]thiazol-3-ium iodide (BCVTI) that specifically recognizes HSO3− was constructed with benzothiazole iodide as the acceptor unit and benzylcarbazole as the donor unit. The sensor BCVTI exhibited orange-red fluorescence by itself due to the intramolecular charge transfer (ICT) effect. When HSO3− was added, BCVTI underwent nucleophilic addition, which destroyed the ICT effect and quenched the fluorescence. At the same time, the color of the BCVTI solution changed from orange-red to colorless, which can detect HSO3− by naked eyes. BCVTI had high selectivity, and its sensing mechanism had been studied by nuclear magnetism and mass spectrometry. In addition, BCVTI can complete the detection of HSO3− within 4 min, with a detection limit as low as 3.3 nM. Finally, the fluorescence sensor BCVTI was also applied to the trace detection of HSO3− in mineral water, wine, and white sugar with satisfactory results. All these results showed that BCVTI could be as a practical sensing platform for analysis of HSO3− in food samples.