Cyanide ion colorimetric chemosensor based on protonated merocyanine in EtOH

This Letter aimed to develop an efficient method for the determination of cyanide ion (CN − ). A novel colorimetric chemosensor 4-[(1 E )-2-(4-hydroxyphenyl)ethenyl]-1-allylpyridinium bromide (HPEAPB) was synthesized. HPEAPB displayed good selectivity toward CN − over other competing anions in ethanol. A color change from yellow to red was immediately observed upon the addition of CN − and the limit of detection (LOD) was 3.4   ×   10 −6   mol   L −1 . The sensing mechanism was discussed by UV–vis, 1 H NMR titration, and a comparison study. Colorimetric test paper for CN − was prepared by attaching HPEAPB to a chromatography paper , which could be used to detect CN − in environmental samples as simply as a pH-indicator paper for pH value. The LOD of the test paper for CN − was 2.0   ×   10 −4   mol   L −1 . This detection method for CN − has potential applications in cyanide ion containing fields by combination of rapid and real-time advantages.