A simple colorimetric chemosensor for relay detection of Cu2+ and S2- in aqueous solution

A simple colorimetric chemosensor 1 was developed for the sequential detection of Cu2+ and S2-. Sensor 1 could rapidly detect Cu2+ by an obvious color change from colorless to yellow. The binding mode of 1 to Cu2+ was determined to be a 1:1 complexation stoichiometry through Job plot and ESI-mass spectrometry analyses. The sensing mechanism of Cu2+ by 1 was proposed by theoretical calculations. Importantly, the detection limit for Cu2+ was found to be 0.12 mu M, which was much lower than the recommended value (31.5 mu M) of the World Health Organization (WHO). Additionally, 1 could detect and quantify Cu2+ in real water samples. Moreover, the resulting 1-Cu2+ complex could be used as a highly selective colorimetric sensor for S2- in the presence of various anions without any interference. The detection limit for S2- was determined to be 1.66 mu M, which was much lower than the guideline (14.8 mu M) recommended by WHO in fresh water. GRAPHICS.