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

• A colorimetric chemodosimeter (AHPEQB) based on quinolinium for cyanide ion was designed.
• AHPEQB displays rapid response, good sensitivity, reversibility and selectivity toward cyanide ion among other competing anions in ethanol.
• AHPEQB can be used for the ultrasensitive determination of cyanide ion concentration in real samples.

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, 1H 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.

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