A novel 5-mercapto triazole Schiff base as a selective chromogenic chemosensor for Cu2+

A novel colorimetric cation sensor bearing phenol, thiol and HC=N groups was designed and synthesized. In a DMSO/H2O (9:1, v/v) solution, the sensor exhibited highly selective recognition of Cu2+ among a range of metal ions tested. In the presence of Cu2+, solutions of the sensor underwent a dramatic color change from colorless to yellow, while the presence of other metal cations such as Zn2+, Pb2+, Cd2+, Ni2+, Co2+, Fe3+, Hg2+, Ag+ and Ca2+ had no effect on the color. The detection limit of the sensor toward Cu2+ is 8.0 x 10(-7) M and an association constant K-a of 4.3 x 10(5) M-1 was measured. The sensing of Cu2+ by this sensor was found to be reversible, with the Cu2+-incluced color being lost upon addition of EDTA. (C) 2011 Elsevier B.V. All rights reserved.