Colorimetric chemosensors designed to provide high sensitivity for Hg2+ in aqueous solutions

The specific colorimetric detection of Hg2+ in the context of interference from coexisting metal ions in aqueous solutions is a challenge. Therefore, a series of easy-to-make Hg2+ calorimetric chemosensors S1 similar to S3, bearing thiourea moiety as binding site and nitrophenyl moiety as signal group, were designed and synthesized. Among these sensors, S3 showed excellent colorimetric specific selectivity and high sensitivity for Hg2+ in DMSO and DMSO/H2O binary solutions. When Hg2+ was added to the solution of S3, a dramatic color change from brown to colorless was observed, while the cations Ca2+, Mg2+, Cd2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Ag+ and Cr3+ did not interfere with the recognition process for Hg2+. The detection limits were 5.0 x 10(-6) and 1.0 x 10(-7) M of Hg2+ using the visual color changes and UV-vis changes respectively. (c) 2012 Elsevier Ltd. All rights reserved.