A new colorimetric chemosensor with an electron-withdrawing group (–NO2) 1 for the detection of CN− and F− has been simply developed. Receptor 1 showed selectively colorimetric responses to CN− in aqueous solution and F− in acetonitrile, respectively. An obvious color change of 1 from yellow to colorless was observed for CN− through a nucleophilic addition mechanism, while F− was detected through a deprotonating mechanism with a distinct color change from pale yellow to orange. The binding modes of receptor 1 with two analytes (CN− and F−) were proposed to be 1 : 1, based on the Job plot, 1H NMR titration, and ESI-mass spectrometry analysis.
