A coumarin containing hemicyanine-based probe for dual channel detection of cyanide ion

Abstract

Cyanide(CN−) is known as one of the most toxic inorganic anions and is harmful to the environment and human health. Its wide use and severe toxicity have led to the development of highly selective cyanide detection, and quantification is desirable. A coumarin-containing hemicyanine-based probe has been developed for highly selective colorimetric and fluorometric detection of cyanide in acetonitrile and aqueous medium. The probe was characterized by 1D NMR (1H and 13C) and HRMS Spectroscopy, and the sensing properties have been studied in colorimetric and fluorometric methods. The high selectivity of the probe for CN− was established by UV–vis and fluorescence spectroscopy in the presence of other competing anions. The probe can detect cyanide as low as 0.7 μM within 90 s. A remarkable change in spectroscopic properties has been observed upon adding cyanide ion. The weakly luminescent probe emitted strongly upon the reaction with CN− which is due to the inhibition of internal charge transfer (ICT) from coumarin to indolinium moiety. Furthermore, the colour change from yellow to colourless and the appearance of a blue luminescence, which can be observed by the naked eye, provides a simple real-time method for cyanide detection, also supported by 1H NMR titration and theoretical study. Furthermore, a paper strip kit loaded with probe has been constructed for a real-time application of CN detection without any interference from other competitive analytes.