A colorimetric Schiff base chemosensor for CN- by naked-eye in aqueous solution

A highly selective colorimetric chemosensor 6,6'-((1E,1'E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(2,4-dichlorophenol) (1) based on the combination of hydrazine and 3,5-dichloro-2-hydroxybenzaldehyde was designed and synthesized. Receptor 1 showed exclusive response toward cyanide by a color change from colorless to yellow in aqueous solution. The binding mode of 1-CN- species was determined to be a 1:1 stoichiometry through Job plot, H-1 NMR titration, and ESI-mass spectrometry analysis. Also, the sensor 1 could be recyclable simply through treatment with a proper reagent such as hydrochloric acid. (C) 2015 Elsevier B.V. All rights reserved.