LAUSR

Abstract The article addresses the synthesis, structure and properties of 2-benzoylamino-1-hydroxyanthraquinone (1a), which can function as a selective colorimetric sensor for the cyanide anion in aqueous media. Compound 1a was prepared in two simple steps in good yield and its structure was confirmed by X-ray diffraction analysis. UV–Vis and NMR spectroscopy, mass spectrometry and quantum chemistry studies revealed that in MeCN–H2O mixtures (95:5, v/v), cyanide ionizes the hydroxyl group of the anthraquinone, which results in a strong bathochromic effect. The association constant of cyanide anion with 1a was measured to be 104.88 M–1; the detection limit is about 0.22 μM. The presence of a benzoylamino group at position 2 of the anthraquinone core has a stabilizing effect on the anionic form of 1a due to the hydrogen bonding between the amide hydrogen atom and the oxygen atom of the ionized hydroxyl group.