A Dual Functional Fluorescent Probe Based on Phenothiazine for Detecting Hg²⁺ and ClO^- and its Applications

For the efficient detection of Hg²⁺ and ClO^-, a double-analyte-responsive fluorescent probe PTB was successfully synthesized by combining N-butyl-3-formyl phenothiazine with hydrazine benzothiazole, and designing a specific reaction site for recognizing two analytes (Hg²⁺ and ClO^-) in a compound. It was shown that probe PTB successfully formed a stable complex with Hg²⁺ in the coordination ratio of 2:1 by using the strong sulfur affinity of Hg²⁺, which resulted in a remarkable "turn-off" effect, with a quenching efficiency of 92.5% and four reversible cycles of Hg²⁺ fluorescence detection. For the fluorescence detection of Hg²⁺, the response time is fast (≤ 2 min) and the detection limit is low (7.8 nM), showing extremely high sensitivity, and the performance is obviously better than that of the reported fluorescent probes for detecting Hg²⁺. In particular, probe PTB has low toxicity and good biocompatibility, and has been successfully used for imaging of Hg²⁺ in living cells. Moreover, probe PTB uses thioether bond and carbon-nitrogen double bond as reaction sites to detect ClO^-, which has large Stokes Shift (149 nm), good selectivity, high quenching efficiency (96.5%) and fast time response (about 10 s), and successfully detects ClO^- in actual water samples.