Study On Synthesis And Their Antibacterial Activity Of Rare Earth Complexes

Rare-earth elements have an important strategic position in the21st century. They are widely used in various fields of national economy and national defense industry, Relying on their unique physical and chemical characteristics, such as optics, electric, magnetism etc.. In recent years, new rare-earth antibacterial materials have obtained more people’s attention due to few side effects, low toxicity, good thermal property and broad antimicrobial spectrums.In the thesis, three ternary complexes1,2,3were synthesized at normal temperature using cinnamic acid,8-hydroxyquinoline and the rare-earth metal nitrates in ethanol medium, which were LaC27H19N2O4·H2O, CeC27H19N2O4·H2O, and YC27H19N2O4·3H2O, respectively. In water medium, three complexes4,5,6of rare-earth pyridine carboxylate were synthesized at60℃. which were LaC21H12N3O12·2H2O, CeC21H12N3O12·3H2O and YC21H12N3O12·3H2O, respectively. The chemical compositions and structures of six complexes were confirmed by modem analytical techniques such as elemental analysis, infrared spectra(IR). ultraviolet spectra(UV), analysis of DTA-TG, and1HNMR spectra.Inhibition zone diameter and Minimum inhibitory concentrations (MICs) of six complexes and their ligands against Escherichia coli, Staphylococcus aureus, Staphylococcus albus, Bacillus subtilis and Micrococcus luteus were studied, which indicated that the six rare-earth complexes had different antibacterial activities. The complexes1,2possessed the strongest antibacterial activities against Staphylococcus albus. Antibacterial activities against five kinds of bacteria of complex3were less than complexes1,2. Complex5revealed the highest activity against Micrococcus luteus. For complexes1,2,4,5, the MIC values were less than100mg·L-1. Complex3, MIC>100mg·L-1. Complex2, MIC=25mg·L-1. Therefore, for the same bacteria, the antibacterial effects of these complexes, with the same ligand were as follows: Ce-complex> La-complex>Y-complex. Antibacterial effects of the rare-earth complexes were obviously superior to the free ligands. Antibacterial activities were enhanced complementary advantages of rare-earth ions and ligands. Complexes1,2.4,5and6possessed excellent antibacterial ability against against five kinds of bacteria, which were classified as Broad-Spectrum antibacterial agent...