Indole derivatives for cyanide detection based on nucleophilic addition and hydrogen-bond interaction.

Abstract Two indole organic salt derivatives 1 and 2 with two potential reactive sites for cyanide were synthesized by very simple method. The compounds exhibit highly sensitive and selective response for cyanide with obvious UV–vis absorption, color change and fluorescence quench. Color change under natural and UV light can be observed easily by naked eyes. Their absorption responses for cyanide are markedly different from the corresponding normal cyanide chemosensors because of N H*CN− intermolecular hydrogen-bond interaction. The difference of absorption spectra between these compounds and the corresponding normal cyanide chemosensors were compared. Their recognition mechanisms for cyanide anions were analyzed by in situ 1H NMR and Job's plots. The analysis indicates that cyanide anions are bonded to C C bonds in conjugated bridge of the compounds. At the same time, N H*CN− intermolecular hydrogen-bond interaction is accompanied. These chemosensors have been successfully applied for determination of CN− in living cells. Graphical abstract Image 1 Highlights • Two indole derivatives with two reactive sites for cyanide detection were developed. • The compounds can recognize CN− with obvious spectra and color change. • CN− is bonded to C C bond in conjugated bridge of the compounds. • The chemosensors were successfully applied for determination of CN− in living cells. • Intermolecular hydrogen-bond interaction may also occur and plays an important role. [ABSTRACT FROM AUTHOR]