Synthesis, crystal structure, antioxidant activities and DNA-binding studies of the Ln(III) complexes with 7-methoxychromone-3-carbaldehyde-(4 '-hydroxy) benzoyl hydrazone

A novel chromone Schiff base, 7-methoxychromone-3-carbaldehyde-(4'-hydroxy) benzoyl hydrazone (L) and its Ln(III) complexes (Ln = La, Eu) were synthesized and characterized. The crystal structure of the La(III) complex was determined by single-crystal X-ray diffraction: crystallized in the orthorhombic system, space group Pbcn, Z = 8, a = 14.595(2) angstrom, b = 20.055(3) angstrom, c = 30.078(5) angstrom, R-1 =0.0657. Fluorescence titration spectra, electronic absorption titration spectra, EB displacement and viscosity measurement indicated that both the ligand and the complexes can bind to DNA via the intercalation mode, and that the binding affinity of the La(III) complex is higher than that of the Eu(III) complex and of the ligand (L). The antioxidant activity experiments show that these compounds also exhibit good antioxidant activities against (OH)-O-center dot and O-2(center dot-). Moreover, the Eu(III) complex exhibits characteristic fluorescence of europium ion in different organic solvents. (C) 2008 Elsevier Masson SAS. All rights reserved.