Simultaneous Detection of Cu2+ and Co2+ by a Water-Soluble Carboxamide-Based Colorimetric Chemosensor

A novel carboxamide-based colorimetric chemosensor ATA-Msal ((E)-3-((2-hydroxy-3-methoxybenzylidene)amino)thiophene-2-carboxamide) for detecting Cu2+ and Co2+ in aqueous solution was synthesized. Sensor ATA-Msal could probe Cu2+ and Co2+ by color change from colorless to pale yellow. According to results of Job plot and ESI-mass, the binding modes of ATA-Msal to Cu2+ and Co2+ were determined to be a 1 : 1 ratio. The detection limits (0.14 mu M and 0.88 mu M) of ATA-Msal for Cu2+ and Co2+ were much lower than WHO standard (31.5 mu M for Cu2+) and US Environmental Protection Agency (EPA) standard (1.70 mu M for Co2+). ATA-Msal can be applicable to real samples and test strips, and F- could be used to distinguish between ATA-Msal -Cu2+ and ATA-Msal -Co2+. The sensing process of Cu2+ and Co2+ by ATA-Msal was demonstrated by UV-vis titration, ESI-mass, EPR, H-1 NMR titration, and DFT.