Visual detection of cyanide ion in aqueous medium by a new chromogenic azo-azomethine chemosensor

Abstract A simple and new chromogenic azo-azomethine chemosensor N′-(5-((2,4-dichloro- phenyl) diazenyl)-2-hydroxylbenzylidene) picolinohydrazide ( L ) has been synthesized as an effective colorimetric sensor for cyanide ion. The sensing behavior of the probe L towards CN − over other anions was examined by naked-eye, UV–vis spectroscopy and NMR studies. L exhibited a selective sensing ability to CN − in DMSO/H 2 O(6:4, v:v) binary solution and DMSO/Tris(10 mM, pH = 7.1, 6:4, v:v) buffer solution by changing color from colorless to yellow. The detection limit was calculated to be 6.4 μM. The recognition mechanism was attributed to deprotonation process according to 1 H NMR titration method. Moreover, test strips coated with L were easily fabricated with low cost and could be used to detect CN − in aqueous solution conveniently.