A Readily Available Red-Emitting Methylthio-Substituted Salicylaldehyde Azine with AIE Feature for Ratiometric Detection of HClO

Developing a simple, selective, and rapid reliable method to monitor hypochlorous acid (HClO) in vivo is very meaningful due to its important physiological and pathological functions. In this research, a novel AIE based fluorescent probe for ratiometric detection of HClO was fabricated by a simple one-step synthesis, in which the methyl sulfide group and salicylaldehyde azine serve as the recognition unit and fluorophore, respectively. This probe was visible-light-excitable, and showed a palpable aggregation-induced emission into the red region with high stability to Cu²⁺ and pH. Oxidation of the methyl sulfide group can be achieved rapidly and specifically by HClO in physiological condition, which enables it to display a rapid, ratiometric fluorescent response to HClO with high selectivity over other biologically pertinent species. By exploiting the probe-based tool, we successfully validated its practical utility in selectively recognizing HClO in living cells via ratiometric fluorescence signals, thereby providing a potential method for investigating the relevant functions of HClO in biosystems.