| In this paper, three types of aminopolycarboxylic acids, ethyleneglycol-bis-(2-aminoethylether)-N, N, N', N'-tetraacetic acid (H4egta), triethylenetetramine-N, N, N', N'', N''', N'''-hexaacetic acid (H6ttha), and propylenediamine-N, N, N', N'-tetraacetic acid (H4pdta), have been selected as ligands, and the ethylenediamine is selected as counter ion. Also, four rare earth metal ions, SmⅢ, EuⅢ, GdⅢand TbⅢhave been chosen as cetral ions to synthesize a series of stable and soluble complexes, they are (enH2)[LnⅢ(egta)(H2O)]2·6H2O (Ln = SmⅢ, EuⅢ, GdⅢand TbⅢ); (enH2)1.5[SmⅢ(ttha)]·4.5H2O; (enH2)3[LnⅢ(ttha)]2·11H2O (Ln = EuⅢ, TbⅢ); (enH2)[Ln2Ⅲ(pdta)2(H2O)2]·8H2O, (Ln = GdⅢ, TbⅢ), respectively. With an aim to get further insight of structure characters of complexes, We fully investigated the molecular structure, crystal structure and coordination number of Ln-APCA-EN (APCA= aminopolycarboxylic acids, EN=ethylenediamine) complex, which lays the groundwork for the interaction of rare earth metal complexes with other various biomolecules, such as amino acids, peptide and protein.This paper is discussed as three part according to the type of ligands.The first part, the octadentate ligand, ethyleneglycol-bis-(2-aminoethylether)-N, N, N', N'-tetraacetic acid (H4egta) is selected as ligand, and ethylenediamine is selected as counter ion, four novel complexes, (enH2)[LnⅢ(egta)(H2O)]2·6H2O (Ln = SmⅢ, EuⅢ, GdⅢand TbⅢ), were successfully synthesized. According to the analysis of single crystal x-ray diffraction, every complex adopts nine-coordinate pseudo-monocapped square antiprism, and they crystallizes in the monoclinic crystal system with P21/n space group. Through hydrogen bonds, the ethylenediamine connect with four adjacent complex anions, forming a 2D ladder-like layer structure. Therefore, it can be seen that the four rare earth metals are similar in the ion radii and characters, if selecting the same ligand and counter ion, they will adopt similar crystal structure.The second part, the decadentate ligand, triethylenetetramine-N, N, N', N'', N''', N'''-hexaacetic acid (H6ttha), is selected as ligand, also the ethylenediamine is selected as counter ion, three novel complexes: (enH2)1.5[SmⅢ(ttha)]·4.5H2O, (enH2)3[LnⅢ(ttha)]2·11H2O (Ln = EuⅢ, TbⅢ) have been successfully synthesized. The X-ray crystal structure analysis reveals that when selecting the same ligand and counter ion, three complexes are all nine-coordinated in geometry of pseudo-monocapped square antiprismatic polyhedron. And they crystallize in the monoclinic crystal system with P21/n space group. However, different from the (enH2)3[EuⅢ(ttha)]2·11H2O and (enH2)3[TbⅢ(ttha)]2·11H2O, there are only two types of ethylenediamine in (enH2)1.5[SmⅢ(ttha)]·4.5H2O. Which form hydrogen bonds with adjacent [SmⅢ(ttha)]3- complex anions, leading to the formation of a 2D ladder-like layer structure. While in (enH2)3[EuⅢ(ttha)]2·11H2O and (enH2)3[TbⅢ(ttha)]2·11H2O, there are two crystallographically independent complex anions with similar coordination environment. And there are three types of ethylenediamine, which form hydrogen bonds with neighboring complex anions, leading to the formation of a 2D ladder-like layer network.The third part, the hexadentate propylenediamine-N, N, N', N'-tetraacetic acid (H4pdta) is selected as ligand, ethylenediamine is selected as counter ion, two novel complexes, (enH2)[Gd2Ⅲ(pdta)2(H2O)2]·8H2O and (enH2)[Tb2Ⅲ(pdta)2(H2O)2]·8H2O have been successfully synthesized. Owing to the existence of propylenediamine, the two complexes are both eight-coordinated in geometry of pseudo-square antiprismatic polyhedron. And they crystallized in the monoclinic with C2/c space group. Further, they form an 1D infinite zigzag chain along b-axis. And the ethylenediamine connects with neighboring complex anions through hydrogen bonds, leading to the formation of a 2D layer structure. |
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