A highly sensitive and selective chemosensor for cyanide

A highly sensitive and selective cyanide chemosensor based on fused indoline and benzooxazine fragment was reported with fast response. The detection of cyanide was performed via the nucleophilic attack of cyanide anion on the oxazine. 1H NMR and MS studies confirmed the cleavage of C–O bond of oxazine and binding of cyanide to the spiro center of oxazine. The specific reaction results in high selectivity for cyanide ion. Addition of cyanide anion to the oxazine in MeCN/H2O solution results in a loss in absorbance at 343 nm and an increase in new absorbance at 411 nm, thus resulting in obvious color changes. Cyanide can be detected down to 1 μM levels in a fast response of less than 30 s with no interference of other anionic species. The cyanide detection method should have potential application in a variety of settings requiring rapid and accurate analysis of cyanide anion for drinking and fresh water.