A new benzimidazolium incorporated chemodosimeter affording dual chromogenic and fluorescence switch-on signaling for the selective targeting of cyanide

[eng] We have designed and synthesized a new chemodosimeter, Benzolin-A, which selectively responds to toxic cyanide by dual colorimetric and fluorescence turnon responses in buffered aqueous DMSO. In the presence of cyanide, we observe absorbance red shift of 108 nm (color changing from colorless to yellow) and fivefold fluorescence enhancement. The 1H NMR studies confirm the nucleophilic addition mechanism, and consistent with the experimental findings, the computational work predicts the feasibility of photoelectron transfer or energy transfer process in the native probe, as well as enhanced internal charge transfer in the Benzolin-A-cyanide adduct. Noteworthily, several background anions, such as F-, Cl-, AcO-, SCN-, HSO4 -, NO3 -, Br-, I- and H2PO4 - exhibit none or insignificant optical perturbations