Antioxidation and DNA-binding properties of binuclear Er(III) complexes with Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxaldehyde and four aroylhydrazines.

The Er(III) complexes are prepared from Er(NO(3))(3).6H(2)O and Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxaldehyde with four aroylhydrazines, including benzoylhydrazine, 2-hydroxybenzoylhydrazine, 4-hydroxybenzoylhydrazine and isonicotinylhydrazine, respectively. X-ray crystal and other structural analyses indicate that Er(III) and every ligand can form a binuclear Er(III) complex with nine-coordination and 1: 1 metal-to-ligand stoichiometry at the Er(III) centre. All the Er(III) complexes can bind to calf thymus DNA through intercalation with the binding constants at the order of magnitude 10(6) M(-1), and they may be used as potential anticancer drugs. All the Er(III) complexes have strong scavenging effects for hydroxyl radicals and superoxide radicals; however, complex containing active phenolic hydroxyl group shows stronger scavenging effects for hydroxyl radicals and complex containing N-heteroaromatic substituent shows stronger scavenging effects for superoxide radicals.