A Selective, Colorimetric and Ratiometric Chemosensor for Hg ²⁺ and Its Application as Test Papers

Chemosensors provide an efficient and low-cost approach to the detection of various metal ions and small molecules. In the present work, we present a detailed investigation of a simple, easily-prepared, yet efficient, coumarin-based sensor for Hg ²⁺ . The sensor is based on a fluorescent group of coumarin. When exposed to Hg ²⁺ , the sensor solution shows a significant color change from yellow to red, and a fluorescence change from green to orange. Further study revealed that the sensor responds solely to Hg ²⁺ , and shows excellent selectivity even in the presence of other potential competition metal ions, including Na ⁺ , K ⁺ , Co ²⁺ , Fe ²⁺ , Cd ²⁺ , Cu ²⁺ , Ni ²⁺ , Ag ⁺ , Zn ²⁺ , Mg ²⁺ , Mn ²⁺ , Pb ²⁺ , Fe ³⁺ . Furthermore, the sensor has been successfully applied to detect Hg ²⁺ in a form of test paper, which may promote easy and effective application of the sensor.