Synthesis, Crystal Structure And Properties Of Rare Earths Aromatic Carboxylic Acid Complexes

Twelve ternary complexes of La(III), Pr(III), Y(III) and Yb(III) have been synthesized with o(m,p)-ClBA and phen; Ten ternary complexes of Eu(III) and Tb(III) have been synthesized with o(m,p)-phthalate and phen; Eight quaternary complexes of Eu(III) and Tb(III) have been synthesized with BA, o(m,p)-MBA, p-PA and phen. These complexes were initially defined by elemental analysis and EDTA titration for rare earth.These complexes were characterized by means of IR, TG-DTG, bacteriostatic activity and luminescence spectra methods. In these complexes, the rare earth ions were bonded to oxygen atoms of carboxylate and nitrogen atoms of phen ligand. All these complexes show fine thermal stability. The structure of two ternary complexes La(p-ClBA)3phen?H2O and Pr(p-ClBA)3phen?H2O have been determined. The structures of the two complexes were similar and they belong to triclinic system, PÄ«space group. The molecules form a centrosymmetric dimeric unit. Each central ion is nine-coordinated. The ligands adopt three kinds of coordination modes: monodentate coordination, bridging bidentate coordination and bridging tridentate coordination.The preliminary antibacterial tests show that the higher the concentration of the complexes are, the stronger the antibacterial activity they exhibit. The majority of these complexes exhibit relatively better activity against Escherichia coli and Staphylococcus aureus than rare earth salts and the ligands.The Eu(III) and Tb(III) complexes exhibit the characteristic emission peaks in the luminescence spectra. However, the emission intensity of the complexes changes due to the different ligands.These results would provide valuable information for synthesis of new effective rare earth luminiscent and antibacterial materials.