Water pollution caused by heavy met

Water pollution caused by heavy metal ions is one of thecrucial issues to be attached great importance in environmentalmanagement.1−3 Among all the heavy metals, mercury is oneof the most common and hazardous elements.4 Mercury ions(Hg2+) have very toxic effects even at a very low concentrationdue to their thiophilic nature to enzymes and proteins.5 Hg(II)ions can be transformed into the potent neurotoxinmethylmercury, which could cause bioaccumulation andmagnification in food chains.6 Therefore, it is urgent todevelop methods for the detection and removal of mercuryions.7−9 So far, a variety of sensors, such as electrochemicalsensors, surface-enhanced Raman scattering (SERS) sensors,and colorimetric sensors have been reported in the past fewyears for the detection of Hg2+.10−12 Among the variousanalysis methods, fluorescence sensors stand out due to theirhigh sensitivity and simplicity.13−17 Particularly, a coumarinbased sensor that can respond to Hg2+ by the desulfurizationprocess has paved a way to develop easily prepared Hg2+sensors.18 Moreover, Hg2+ could form HgS, as a solid