NMR and ab initio studies of Mg2+, Ca2+, Zn2+, Cu2+ alizarin complexes

Abstract Complexation of Mg 2+ , Ca 2+ , Zn 2+ and Cu 2+ with alizarin, characterized by NMR and theoretical studies (DFT, B3LYP/6-31G( d , p ) PCM and NMR GIAO B3LYP/IGLOIII), indicated that the metal ion is attached to two hydroxyl groups in a bidentate mode. The alternative complexation in the bidentate mode, with only one hydroxyl group and a carbonyl oxygen, is less possible as it has a higher energy.