Synthesis, characterization and antioxidative activity of new rare earth complexes of 6-hydroxy chromone-3-carbaldehyde-(4′-hydroxy)benzoyl hydrazone

A new ligand, 6-hydroxy chromone-3-carbaldehyde-(4'-hydroxy) benzoyl hydrazone (H3L), was prepared by condensation of 6-hydroxy-3- carbaldehyde chromone with 4-hydroxy benzoyl hydrazine. Four rare earth complexes of formula [Ln( H3L)(2)( NO3) (2)] center dot NO3 [ where Ln( III) La ( 1), Sm (2), Eu (3) and Dy (4)] have been synthesized and characterized on the basis of IR spectra, UV spectra, elemental analyses, molar conductivity, and thermal analyses. Suppression ratios for O-2(-) (a) and OH. (b) of the ligand and its complexes were studied by spectrophotometric methods. The experiments show that IC50 (a) and IC50 (b) of the complexes are 24.07 - 57.32 and 6.97 - 14.08 mu M, respectively. For the ligand, IC50 (a) and IC50 (b) are 148.29 and 15.67 mu M, respectively. The La (1), Sm (2), Eu (3) complexes are better effective inhibitors for OH center dot(.) than mannitol, indicating that the complexes suppress O-2(-) and OH center dot(.) and are more effective antioxidants than the ligand.