An ICT-based chemodosimeter for selective dual channel sensing of cyanide in an aqueous solution

Abstract

Herein, using intramolecular charge transfer (ICT) transition as a signaling mechanism, a quinoline–benzothiazolium hybrid was designed, synthesized, and developed as a dual channel (colorimetric/turn-on fluorometric) sensor for cyanide in aq. HEPES buffer/DMF (70 : 30 v/v; pH 7.2). This receptor can detect cyanide with very high selectivity and instantaneous response. The mechanism of sensing involves nucleophilic addition of CN⁻ to the C atom of the CN bond of benzothiazolium moiety. This irreversible addition blocks the π-conjugation and ICT transition between quinoline and benzothiazolium moieties and consequently alters the colour and spectral properties. The results of electronic, fluorescence, and ¹H & ¹³C NMR spectral studies corroborated well with those of the DFT calculations.