Reaction-based colorimetric and ratiometric fluorescence sensor for detection of cyanide in aqueous media

A stilbene-based compound (1) has been prepared and was highly selective for the detection of cyanide anion in aqueous media even in the presence of other anions, such as F^-, Cl^-, Br^-, I ^-, ClO₄^-, H₂PO₄ ^-, HSO₄^-, NO₃^-, and CH₃CO₂^-. A noticeable change in the color of the solution, along with a prominent fluorescence enhancement, was observed upon the addition of cyanide. The color change was observed upon the nucleophilic addition of the cyanide anion to the electron-deficient cyanoacrylate group of 1. The spectral changes induced by the reaction were analyzed by comparison with two model compounds, such as compound 2 with dimethyl substituents and compound 3 without a cyanoacrylate group. An intramolecular charge-transfer (ICT) mechanism played a key role in the sensing properties, and the mechanism was supported by DFT/TDDFT calculations. Sense and sensitivity: A highly efficient and selective colorimetric and ratiometric fluorescent sensor for detection of cyanide in aqueous media has been developed. This sensor exhibits a distinctive color change upon reaction with cyanide, along with significant fluorescence amplification. The sensing mechanism is discussed with the aid of spectral analyses and DFT/TDDFT calculations.