Selective colorimetric and fluorimetric detection of cyanide in aqueous solution using novel heterocyclic imidazo-anthraquinones

Novel receptors based on imidazo-anthraquinone system containing thiazole, (benzo)furan, thiophene and imidazole heterocycles at position 2 were synthesized. The photophysical properties of compounds 1–8 were studied by UV–vis and fluorescence spectroscopy in acetonitrile. All anthraquinone derivatives exhibited great selectivity for the cyanide anion over other anions in acetonitrile/water (9:1) solution showing a distinct colour change from yellow to orange and the fluorescence emission was switched “off”. The binding stoichiometry between the receptors and the anions was found to be 1:1. Moreover, chemosensors 1–8 exhibit a high sensitivity being capable to detect cyanide in very low concentrations (below 4 μM).