A multifunctional near‐infrared dual‐channel off‐on‐off probe for sequential detection of fluoride and hypochlorous acid: Multimatrix applications

Abstract Fluoride (F − ) and hypochlorous acid (HClO) are chemically distinct yet environmentally and biologically critical analytes. F − is widespread in soil, water, and food additives, whereas HClO acts as a key in vivo immune molecule and food disinfectant; abnormal levels of either pose significant risks. Herein, we report a novel multifunctional near‐infrared (NIR) dual‐channel probe (DHM) for sequential F − /HClO detection with an “off‐on‐off” response. The tert‐butyldiphenylsilyl (TBDPS) moiety in DHM quenches its initial fluorescence (“off” state). F − specifically cleaves TBDPS, generating a phenolate group with enhanced electron‐donating capacity that activates intramolecular charge transfer, switching DHM to “on” with dramatically enhanced NIR red fluorescence. Subsequently, HClO oxidizes the malononitrile moiety of the F − ‐activated product, disrupting conjugation and inducing a red‐to‐blue switch with a massive 190 nm spectral separation, thereby achieving zero signal crosstalk. DHM exhibits rapid response, excellent anti‐interference ability, and robust performance in complex matrices. Crucially, this strict “first F − , then HClO” dependency perfectly aligns with the pathological timeline of fluoride‐induced oxidative stress and the practical demands of municipal water monitoring. It has been successfully applied for dual‐channel imaging in Huh7 cells and mice, as well as quantitative detection in water/food samples with satisfactory results, showing great potential in related fields.