Reaction-Based Ratiometric Chemosensor for Instant Detection of Cyanide in Water with High Selectivity and Sensitivity

A highly selective chemosensor 1 based on an acylhydrazone group as binding site and naphthalene group as the fluorescence signal group were described, which could instantly detect CN- in water with specific selectivity and high sensitivity. The detection of cyanide was performed via the nucleophilic attack of cyanide anion on the carbonyl group, which could be confirmed by (HNMR)-H-1, (CNMR)-C-13, ESI-MS and DFT calculations. The addition of CN- to sensor 1 induced a remarkable color change from colorless to yellow and generated a blue fluorescence, these sense procedure could not interfered by other coexistent competitive anions (F-, Cl-, Br-, I-, AcO-, H2PO4-, HSO4-, ClO4-, SCN-, S2-, NO3- and SO42-). The detection limits were 5.0x10(-7)M and 2.0x10(-9)M of CN- using the visual fluorescent color changes and fluorescence spectra changes respectively, which is far lower than the WHO guideline of 1.9x10(-6)M. Test strips based on sensor 1 were fabricated, which could act as a convenient and efficient CN- test kit to detect CN- in pure water for in-the-field measurement.