A Selective, Colorimetric and Ratiometric Chemosensor for Hg2+ 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 Hg2+. The sensor is based on a fluorescent group of coumarin. When exposed to Hg2+, 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 Hg2+, and shows excellent selectivity even in the presence of other potential competition metal ions, including Na+, K+, Co2+, Fe2+, Cd2+, Cu2+, Ni2+, Ag+, Zn2+, Mg2+, Mn2+, Pb2+, Fe3+. Furthermore, the sensor has been successfully applied to detect Hg2+ in a form of test paper, which may promote easy and effective application of the sensor.