Crystal Structures, Antioxidation, and DNA Binding Properties of SmIII Complexes

The dinuclear SmIII complexes with 1:1 metal to ligand stoichiometry were prepared from Sm(NO3)3·6H2O and three anionic tetradentate Schiff-base ligands derived from 8-hydroxyquinoline-2-carboxyaldehyde with benzoylhydrazine, 2-hydroxybenzoylhydrazine, and isonicotinylhydrazine, respectively. All the ligands and complexes can bind strongly to calf thymus DNA through intercalation with the binding constants at 105–106 M–1, but complexes present stronger affinities to DNA than ligands. All the ligands and complexes have strong abilities of antioxidation, but complexes and ligands containing an active phenolic hydroxy group show stronger scavenging effects on hydroxyl radical, and SmIII complex containing N-heteroaromatic substituent shows stronger scavenging effects for superoxide radical.