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

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 C?N bond of benzothiazolium moiety. This irreversible addition blocks the -conjugation and ICT transition between quinoline and benzothiazolium moieties and consequently alters the colour and spectral properties. The results of electronic, fluorescence, and H-1 & C-13 NMR spectral studies corroborated well with those of the DFT calculations.