A novel reaction-based ratiometric fluorescent probe with large Stokes shift for the detection of Hg2+ in river sample

Based on Hg2+-promoted desulfurization-hydrolysis of the diphenylphosphinothioate moiety, a novel ratiometric fluorescent probe 1 for Hg2+ using hemicyanine as the fluorophore was designed and synthesized. In sensing of Hg2+, the maximum fluorescence emission and absorption peaks of 1 shifted from 450 nm to 504 nm and from 351 nm to 376 nm respectively, accompanied by color change from colorless to green under illumination with a 365 nm UV lamp. 1 not only exhibited remarkable change in the ratios of both absorbance (A376 nm/A351 nm) and fluorescence intensity (F504 nm/F450 nm), but also had large Stokes shift, fast response, excellent sensitivity, and high selectivity for Hg2+. Furthermore, 1 was successfully applied for Hg2+ detection in river water sample.