Multispectroscopic and theoretical studies on rapid, selective and sensitive visual sensing of cyanide ion in aqueous solution by receptors possessing varying HBD property.

Raja Lakshmi, P.; Manivannan, R.; Jayasudha, P.; Elango, Kuppanagounder P.

Three new benzoquinone-imidazole ensembles possessing varying number (0, 1 and 2) of electron-withdrawing bromo substituents on the quinone ring have been designed, synthesized, characterized and employed as receptors in cyanide sensing. These receptors colorimetrically sense cyanide ion selectively and sensitively in aq. 4-(2-hydroxyethyl)-1-piperazineethanesulphonic acid (HEPES) buffer-acetonitrile (ACN) (8:2 v/v) medium with striking colour change that can easily be seen visually. Fluorescence spectral studies revealed that the receptors form strong complex at 1:1 stoichiometry with cyanide ion. The binding constants for the complexes were found to be in the order of 105-107 M−1 and increase with increasing number of bromo substituents on the quinone ring. The detection limit of cyanide by these receptors lay in the range of 10−8 M. The effects of the number of bromo substituents on the absorption maximum, reduction potential and H-bond donor (HBD) property of imidazole N-H are discussed. The results of spectral studies corroborate well with those of electrochemical and theoretical studies. An easy-to-use test strip was prepared to test cyanide in aqueous solution of sodium cyanide prepared using deep-well water.

CYANIDES; COLORIMETRY; QUINONE; FLUORESCENT probes; AQUEOUS solutions

Research on Chemical Intermediates, 2018, Vol 44, Issue 4, p2807

0922-6168

Academic Journal

10.1007/s11164-018-3262-y