Fluorescent and chromogenic probes bearing salicylaldehyde hydrazone functionality for cyanide detection in aqueous solution

Two highly selective cyanide probes with a salicylaldehyde hydrazone functionality as binding site were reported with fast response. The detection of cyanide was performed via the nucleophilic attack of cyanide anion on the imine group of the probes with a 1:1 binding stoichiometry, which could be confirmed by 1H NMR and MS studies. The specific reaction results in a prominent fluorescence enhancement for one of the probes and a color change from pale yellow to dark red for the other. The cyanide detection method described here should have potential application as a new family of probes for detecting cyanide in aqueous solution.