Chlorination-induced p K a decrease: an improved strategy to design ratiometric hypochlorite fluorescent probes with ideally high selectivity.

Based on the selective ClO - -triggered chlorination reaction and the subsequent p K a decrease of phenols, a new strategy was developed for rationally designing ratiometric ClO - fluorescent probes with high selectivity. By investigating the fluorescence responses of 6-cyano-2-naphthol toward ClO - and the p K a -dependent response mechanism, we developed a rapid, sensitive and selective two-photon ratiometric fluorescent probe, Naph-DFOB, to detect ClO - . This probe displayed a ratiometric fluorescence change (from 509 nm to 628 nm) toward ClO - and was successfully applied to image intracellular ClO - in living cells with two-photon excitation. Using Naph-DFOB as a useful tool, the investigation of lipopolysaccharide (LPS)-induced acute lung injury in a mouse model was effectively performed.