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

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.