Studies On The Synthesis, Fluorescence Properties Of Chiral Rare Earth Complexes

Rare earth complexes are excellent luminescence materials, because of the lanthanide ions'parculiar characteristic. So the study of rare earth complexes luminescence, being the cross science of inorganic materials luminescence, organic materials luminescence and biologic materials luminescence, is very important for fundamental and applied research. At first, the thesis reviewed the basic theories of rare earth complexes, and introduced the classification and application of the rare earth complexes. At the same time, the thesis described the research current situation and trend of the rare earth complexes. On this basis, the thesis introduced the influence factors of complexes fluorescence detailedly. Two kinds of thiophene-amide ligands was synthesized and eight chiral complexes were obtained. We found the ligands could sensitize the rare earth luminescence, and also discovered the complexes'fluorescence corresponding their own fluorescence from fluorescence detection. This study would be useful for the selection of chiral ligands for rare earth complex. There are some parts following in this paper.1. Preparation for chiral ligandsThe thiophene-2,5-dicarboxylic was the initial reaction material , four amide ligand of thiophene–methyl ester were obtained via the reactions of L-leucine methyl ester hydrochloride, L-Phenylalanine methyl ester hydrochloride, L-alanine methyl ester hydrochloride, L-Tryptophan methyl ester hydrochloride and thiophene-2,5-dicarbonylic dichloride. Then on the base of the synthesis of amide, two kinds of ligand of carboxylic acid, 2,5-thiophenedicarboxyl-L-leucine amide and 2,5-thiophenedicarboxyl-L- phenylalanine acid, which is good for coordination were obtained from the hydrolyzation of ester .Furthermore, two crystal of chiral ligands of them have been obtained.we found the ligand had good graphic conjugate so they could improve the complexes effectively absorb energy more effectively and also promote complexes'ability of luminescence.2. The synthesis of chiral complexesThe more effective luminescence ions, Sm(III), Dy(III), Eu(III) as well as La(III) that no any luminescence in UV-vis range were selected for the center ion of complex as source of luminescence in this paper. And eight chiral complexes in two families were have been obtained and the condition of experiment was discussed here.3. Characterization of complexes and study on the properties of fluorescenceAfter the infrared spectrum being obtained, we found that the amide group of ligand hardly coordinate with ion due to the existence of hydrogen born between the molecule and the present of steric hindrance and coordination carried out with the carboxylic group in the second kind of ligand forming the chiral complex. The Thermogravity-Differential Thermal Analysis showed the composition of complexes. And in the Solid luminescent spectrum, every characteristic peak of chiral complexes was obtained. Moreover, the spectrum of the complexes of La(III) showed there is a strong emission in ultraviolet-visible zone.4. Result and discussionThe results above were analyzed and showed the affect of coordination between the triplet T1 of two carboxylic ligand and the vibration energy state of four rare earth ion were considerably different. The best luminescence affect is the 2,5-thiophenedicarboxyl-L-leucine-La(III) complex and the better luminescence of La(III) is because of the antenna affect of ligand.