Boranil-phenothiazine conjugates with dual-state emission for ratiometric tracking of HClO in food samples and injured liver cells.

Hypochlorous acid (HClO) is applied as a disinfectant in food processing and sanitation, while excessive residues may pose potential risks to food safety and human health. Therefore, the development of sensitive, rapid, and reliable analytical methods for HClO detection is of considerable importance. Herein, an innovative donor-acceptor (D-A) fluorophore, HC-SN, formulated from an asymmetric phenothiazine-boron difluoride complex, is developed for ratiometric sensing and imaging of HClO. Owing to its significantly twisted molecular structure, HC-SN effectively suppresses π-π stacking and exhibits prominent dual-state emission characteristics, achieving exceptional photoluminescence quantum efficiencies across both solvated and solid phases. Upon the HClO-triggered specific oxidation of the thioether moiety, the intramolecular charge transfer (ICT) process is modulated, leading to a distinct ratiometric fluorescence response accompanied by a significant hypsochromic shift in the emission spectrum. The probe displays excellent analytical performance, featuring remarkable specificity, ultrafast reaction kinetics (under 30 s), and an ultrasensitive detection threshold of 66.87 nM. In addition, HC-SN permits accurate quantification of HClO in food-related liquid samples and was fabricated into fluorescent test strips for naked-eye screening. Importantly, its applicability is further demonstrated by an acetaminophen-induced liver injury cell model. These results suggest that HC-SN provides a practical and versatile platform for HClO monitoring in food safety analysis and related biological systems.