Syntheses And Structural Analyses Of Y^Ⅲ, Eu^Ⅲ, Lu^Ⅲ-H₄egta Complexes And Researches On Interaction With Protein Molecules

In this paper, H4egta(ethyleneglycol-bis-(2-aminoethylether)-N, N, N′, N′-tetraacetic acid) was choosen as ligand, and three kinds of rare earth metal ions(YIII, LuIII and EuIII) were chosen as central metal ions, four novel rare-earth metal aminopolycarboxylic acid complexes were successfully synthesized. They were determined as(en H)[LuIII(egta)]·2H2O,(en H2)[YIII(egta)(H2O)]2·6H2O,(NH4)[LuIII(egta)]·H2O and [EuIII(eg3a)(H2O)2]·5H2O. Through analysis and study on the structures of these four novel complexes, it was further confirms that ions radius and electron structurals of central metal ions have significant effect on the structures and configurations of rare-earth metal aminopolycarboxylic acid complexes. In addition, this thesis also researches the interactions between these three Eu(III) complexes((NH4)[EuIII(edta)(H2O)3]·H2O,(NH4)4[EuIII2(dtpa)2]·10H2O and(NH4)3[EuIII(ttha)]·5H2O) having different aminopolycarboxylic acid ligands and Bovine Serum Albumin(BSA). The paper is introduced in three parts.In the first part, we chose octadentate H4egta(ethyleneglycol-bis-(2-aminoethylether)-N, N, N′, N′-tetraacetic acid) as ligand, Lu(III) and Y(III) as central metal ions, ethylenediamine(en) as counter ion, successfully synthesized two novel rare-earth metal aminopolycarboxylic acid complexes,(en H)[LuIII(egta)]·2H2O and(en H2)[YIII(egta)(H2O)]2·6H2O. The molecular structures, coordination structures and crystal structures of(en H)[LuIII(egta)]·2H2O and(en H2)[YIII(egta)(H2O)]2·6H2O have some differences due to their different central metal ions.(en H)[LuIII(egta)]·2H2O adopts a mononuclear eight-coordinate square antiprismatic(SAP) conformation, and crystallizes in a monoclinic crystal system and Pca2(1) space group. Meanwhile,(en H2)[YIII(egta)(H2O)]2·6H2O takes a mononuclear nine-coordinate monocapped square antiprism(MC-SAP) conformation, and the complex crystallizes in the monoclinic crystal system with P2(1)/C space group.(en H)[LuIII(egta)]·2H2O and(en H2)[YIII(egta)(H2O)]2·6H2O are alike in that there are four complexes molecules in one unit cell. In addition, every four complex anions([YIII(egta)(H2O)]22–are interconnected together by sharing ethylenediamine(N(3)-C(15)-C(15)-N(3)), forming a basic SBU conformation. The two neighboring SBU are further linked through hydrogen bond, leading to the formation of 2D network in plane.。In the second part, we also chose H4 egta as ligand, Lu(III) and Eu(III) as central metal ions, ammonia is used to adjust acidity, successfully synthesized two rare-earth metal aminopolycarboxylic acid complexes,(NH4)[LuIII(egta)]·H2O and [EuIII(eg3a)(H2O)2]·5H2O. Their molecular structures and crystal structures were determined by FT-IR spectroscopy, thermal analysis and single crystal X-ray diffraction techniques. We found when the Eu(III) is chosen as central metal ions, the octadentate egta ligand loses one carboxylic acid group, and became a asymmetric eg3 a ligand during synthesis. But the novel complex is composed of eg3 a ligand and EuIII ion still adopt nine-coordinated, the coordination environment have two water molecules. However, when the Lu(III) is chosen as central metal ions, the egta ligand in the complex of(NH4)[LuIII(egta)]·H2O remains unchanged and the integrity of egta ligand was stored. So, it can be conjectured that the symmetric H4 egta in the presence of Eu3+ ion could obtain novel asymmetric eg3 a compounds. Perhaps, this method can be applied to synthesize other novel asymmetric aminopolycarboxylic acid compounds. Thus, the decarboxylation reaction that symmetric aminopolycarboxylic acid ligand become asymmetric aminopolycarboxylic acid ligand is caused by some rare earth ions. It will open up a new approach for synthesis of asymmetric aminopolycarboxylic acid compound.In the third part, firstly, three complexes of(NH4)[EuIII(edta)(H2O)3]·H2O,(NH4)4[EuIII2(dtpa)2]·10H2O and(NH4)3[EuIII(ttha)]·5H2O were synthesized and characterized in aqueous solution, respectively. And then, the interactions between these three Eu(III) complexes and BSA molecules are studied, and the fluorescence quenching mechanisms of BSA by these three Eu(III) complexes were investigated. Finally, the effect of these three Eu(III) complexes on conformations and binding sites of BSA molecules were studied by circular dichroism(CD) and synchronous fluorescence spectroscopies.