Influence of cetophenolic and diphenolic intramolecular hydrogen bonding on the chromatographic and spectroscopic properties of hydroxyanthraquinones

Anthraquinones have been widely employed for dyeing textiles in combination with various mordants. Many papers have dealt with the modification of optical properties induced by the formation of dye complexes under various pH conditions. This paper deals with the characterization of diphenolic intramolecular hydrogen bonding via molecular modeling and cetophenolic interactions by FT-IR spectroscopy to determine their effect on the spectroscopic and chromatographic properties of hydroxyanthraquinones (anthraflavic acid, alizarin, quinizarin and purpurin). The formation of cetophenolic hydrogen bonding induces a substantial bathochromic shift to the visible absorption band. Moreover, it implies that the constitution of hypercyclised aromatic systems is potentially responsible for the fluorescence of quinizarin and purpurin. This study also demonstrates the modification of the chromatographic retention of dihydroxyanthraquinones on apolar stationary phase consequent to the monopolization of polar groups involved in the formation of such interactions.