A novel dual-responsive fluorescent probe for moisture detection and hypochlorite sensing

Abstract

In this work, a novel phenothiazine-based organic small molecule fluorescence probe (PEIF) was designed and synthesized through Knoevenagel condensation reaction for moisture detection and hypochlorite (ClO−) sensing. The essential photophysical properties of PEIF were evaluated. Interestingly, the probe emitted intense red fluorescence in 1,4-dioxane compared to in water. A good linear relationship was acquired between fluorescent intensities of PEIF at 640 nm and the water content (0.0−0.8 Vol%) in 1,4-dioxane. The probe PEIF demonstrated outstanding sensitivity towards moisture in 1,4-dioxane with a low detection limit of 0.009 % (v/v). Furthermore, the fluorescence detection of ClO− by PEIF featured high sensitivity (LOD = 19.7 nM), good selectivity, large Stokes shift, and rapid response. The detection mechanism of hypochlorite was proposed and verified by DFT calculations, HRMS, and 1H NMR methods. To our knowledge, this is the first phenothiazine-based dual-responsive fluorescent probe for the detection of trace water in 1,4-dioxane and ClO−. We have proved the potential of probe PEIF for the effective determination of ClO− in practical water samples. Besides, this probe was also successfully used for the bioimaging of ClO− in vegetable cells and live zebrafish.