Crystal Structures, Antioxidation, and DNA Binding Properties of Sm-III Complexes

The dinuclear Sm-III complexes with 1:1 metal to ligand stoichiometry were prepared from Sm(NO3)(3)center dot 6H(2)O 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 10(5)-10(6) 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 Sm-III complex containing N-heteroaromatic substituent shows stronger scavenging effects for superoxide radical.