Schiff base complexes of rare earth metal ions: Synthesis, characterization and catalytic activity for the oxidation of aniline and substituted anilines

Several new lanthanide complexes of Pr(III), Sm(III), Gd(III), Tb(III), Er(III) and Yb(III) with the sodium salt of the Schiff base, 2-[(5-bromo-2-hydroxy-benzylidene)-amino]-5-methyl-pentanoic acid, derived from leucine and 5-bromosalicylaldehyde have been synthesized. These complexes having general formula [Ln(HL)(NO3)2(H2O)]·NO3 were characterized by elemental analysis, UV–vis., FT-IR, EPR, Mass spectrometry and Thermal analysis. The FT-IR spectral data suggested that the ligand behaves as a tridentate ligand with one nitrogen and two oxygen donor atoms, sequence towards central metal ion. From the analytical data, the stoichiometry of the complexes was found to be 1:1 (metal:ligand). The physico-chemical data suggested eight coordination number for Ln(III) Schiff base complexes. Thermal behaviour (TGA/DTA) and fluorescence nature of the complexes were also studied. The Gd(III) Schiff base complex was found to be an efficient catalyst for the oxidation of aniline and substituted anilines under mild conditions.