A new Schiff-base chemosensor for selective detection of Cu and Co and its copper complex for colorimetric sensing of S in aqueous solution.

A new Schiff-base colorimetric chemosensor 1 was developed for the detection of Cu, Co and S. Sensor 1 could simply monitor Cu and Co by a color change from colorless to yellow. The binding modes of 1 to Cu and Co were determined to be a 2 : 1 complexation stoichiometry through Job's plot and ESI-mass spectrometry analysis. The detection limits (0.02 μM and 0.63 μM) for Cu and Co were lower than the recommended values (31.5 μM and 1.7 μM) by the World Health Organization (WHO) for Cu and the Environmental Protection Agency (EPA) for Co, respectively. Importantly, 1 could detect and quantify Cu in real water samples. In addition, the Cu-2·1 complex could be used as a highly selective colorimetric sensor for S in the presence of other anions without any interference. Moreover, the sensing mechanisms of Cu and Co by 1 were explained by theoretical calculations.