Highly selective reaction based colorimetric and fluorometric chemosensors for cyanide detection via ICT off in aqueous solution

In the present work, thiazole functionalized receptors, S1 and S2, containing aminophenol as a signaling unit have been prepared and evaluated by UV-vis and fluorescence methods. These receptors consisting of conjugated benzothiazol-aminophenol system, which exhibited rapid and selective response towards cyanide anion. These two probes showed dramatic color change from wine red/purple to colorless, and optical quenching was also observed upon addition of CN- ions based on intramolecular charge transfer (ICT) transition in aqueous media. The detection limit of the probe S1 and S2 for CN- was calculated as 3.6 and 4.2 mu M by spectro-photometric, 0.5 and 0.6 mu M by spectrofluorophotometric methods, respectively. The binding stoichiometry between probes and cyanide was found to be 1:1, and the binding mechanism was also proposed.