Fluorometric and colorimetric sensor for selective detection of cyanide anion by dibenzosuberenone-based dihydropyridazine in aqueous solution.

A new chemosensory based on deprotonation and intramolecular charge transfer (ICT) was developed to detect cyanide in food samples. Deprotonation was facilitated by increasing the acidity of the NH proton in the dibenzosuberenone-based dihydropyridazine chemosensor Pz3 with -CN substituents. Addition of cyanide to acetonitrile and aqueous acetonitrile solution (1/9) of Pz3 resulted in their significant color change from colorless to purple in visible light, accompanied by a strong red shift in the absorption spectrum. Meanwhile, the near-infrared (NIR) emission (ex. 525 nm, em. 670 nm) of Pz3 resulting from deprotonation showed fluorescence switching behavior to detect the cyanide anion. While the acidic NH protons interact with basic anions as F, CN, OAc and HPO in organic solution (MeCN), just CN ions interact with in aqueous organic solutions (HO-MeCN 1/9 HEPES pH 7.4). The limit of detection of cyanide from the fluorescence spectrum is 80 nM, which is well below the value determined for drinking water by World Health Organization (WHO). The interference effect of cations and anions showed that Pz3 could play an important role in the determination of waste NaCN. In addition, Pz3 successfully carried out the selective detection of cyanide in food samples such as bitter almonds and sprouting potatoes.