Visual and reversible detection of cyanide ions in protic solvents by a novel colorimetric receptor

A novel colorimetric chemodosimeter for cyanide (CN − ) and 1-allyl-4-[2-(4-hydroxyphenyl)ethenyl)]-quinolinium bromide (AHPEQB) was designed and synthesized by condensation and terminal N alkyl reaction. AHPEQB exhibited highly selective and sensitive recognition properties toward CN − over other competing anions in ethanol, a protic solvent, with a 1:1 binding stoichiometry and a detection limit of 1.7 × 10 −6  mol L −1 . AHPEQB also displayed rapid colorimetric response that could be readily observed by the naked eye and good reversibility . The sensing mechanism of the proposed chemodosimeter was studied by UV–Vis, 1 H NMR titration, and comparison 1-allyl-4-[2-(4-acetoxyphenyl)ethenyl)]-quinolinium bromide (AAPEQB). The colorimetric chemodosimeter showed high accuracy in determining the concentration of CN − in real water samples.