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

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/HO(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 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.