A PET based colorimetric/fluorescent dual-signal probe for selective detection of hypochlorite in real water samples

As a potent oxidizing agent, hypochlorite is pervasive across various terminal disinfection processes, including water treatment, household blenching and medical sterilization. Thus, the specific visualization identification of hypochlorite in real water samples is crucial for assessing water quality safety and pollutant toxicity. Herein, a novel turn-on colorimetric/fluorescent dual-signal probe AMXM based on 6‑methoxy-2,3-dihydro-1H-xanthene-4-carboxaldehyde scaffold has been successfully designed and synthesized for highly selective and sensitive detection of ClO⁻ in real water sample. Upon the addition of hypochlorite, the solution's color visibly changes from red to yellow to the naked eye, and a strong yellowish green fluorescence is observed under UV light at 365 nm. AMXM demonstrates an excellent linear response (R² = 0.9922), with a low detection limit of 56.2 nM, and is unaffected by other potential interfering substances. The mechanism of AMXM’s response to hypochlorite ions was confirmed through ¹H NMR spectroscopy and density functional theory (DFT) calculations. Furthermore, AMXM was successfully applied to paper test strips and used for the quantitative determination of hypochlorite ions in four real water samples.