Synthesis, crystal structure, antioxidation and DNA-binding properties of the Ln complexes with 1-phenyl-3-methyl-5-hydroxypyrazole-4-carbaldhyde-(benzoyl)hydrazone

Two lanthanide complexes (Ln = La, Pr) with a PMFP Schiff-base, 1-phenyl-3-methyl-5-hydroxypyrazole-4-carbaldhyde-(benzoyl)hydrazone (H2L) were synthesized and characterized. The crystal structure of the La complex was determined by single-crystal X-ray diffraction, the coordination polyhedron is a tricapped trigonal prism configuration with the nine-coordinate atoms composed of three nitrogens and six oxygens from three ligands. The complex crystallized in the monoclinic lattice with a space group P2/c. Electronic absorption titration spectra, fluorescence titration spectra, EtBr competitive experiment, viscosity measurement and CD spectra indicate that all the complexes can strongly bind calf thymus DNA, presumably via groove binding and intercalation mechanism. Furthermore, investigations of antioxidation properties show that all the complexes have some scavenging effects for hydroxyl radicals.