A new colorimetric chemosensor 1 was developed by a combination of 4-(p-tolyl)thiazol-2-amine and 2-hydroxy-1-naphthaldehyde. Sensor 1 showed selective colorimetric responses to CN− and S2− in aqueous solution. A clear color change of 1 from yellow to colorless was observed with CN− through a nucleophilic addition mechanism, while S2− was detected through a deprotonation mechanism with a distinct color change from yellow to orange. The binding stoichiometries of 1 with CN− and S2− were proposed to be 1 : 1, based on the Job plot, 1H NMR titration and ESI-mass spectrometry analysis. Additionally, the sensing mechanisms of 1 for CN− and S2− were theoretically explained by DFT and TD-DFT calculations. Moreover, 1 could be used to quantify CN− in water samples.
