Liquid-Liquid Extraction and Liquid Chromatographic Studies on Interactions of Inorganic Anions with Coordinatively Unsaturated Copper(II) Complexes of Heterocyclic Azo Compounds

The interactions between Cu(II) complexes with heterocyclic azo compounds and several anions were studied by equilibrium analysis of ion-pair extraction, RP-HPLC of metal complexes, and ion chromatography of anions on an ODS column coated with Cu(II) complexes of the long alkyl derivatives. Both ion-pair extraction and HPLC studies demonstrated that a dicationic complex with 8-(3,5-dibromo-2-pyridylazo)-5-aminoquinoline interacted with anions stronger than a monocationic complex with 2-(2-pyridylazo)methylphenol. Anions were more retained on the column coated with dicationic Cu(II) complex. Such differences were quantitatively ascribed to the first ion-pair formation of the dicationic complex giving a monocationic species.