Tackling the Selectivity Dilemma of Benzopyrylium-Coumarin Dyes in Fluorescence Sensing of HClO and SO2.

Benzopyrylium-coumarin fluorescent probes for sensing hypochlorous acid (HClO) or sulfur dioxide (SO2) are unable to distinguish between HClO and SO2 because the two compounds can react with the 4-position of benzopyrylium-coumarin dyes through the nucleophilic attack. In the current work, we introduced a phenoxazine moiety to the benzopyrylium-coumarin dye to synthesize a new fluorescent probe PBC1, which can dually sense HClO and SO2 and generate distinct fluorescence signals with rapid response time and high sensitivity and selectivity. Moreover, probe PBC1 was also successfully utilized to detect intracellular HClO and SO2 in HeLa cells and zebrafish.