The Synthesis, Structure And Properties Of Coordination Complexes Based On Imidazolecarboxylic Acid And Lanthanide

Metal-organic complex, as a kind of novel molecular functional material, has good design and flexible tailoring. These complexes have not only novel structures, but also broad application value in the fluorescent material, ion exchange, magnetic, catalysts and anticorrosion of metal and so on. The earth-organic complexes draw some attention from the owing to their novel topological structure, high fluorescence intensity, the advantages of good monochromaticity and non-oxidate.In this paper, we chosed N-containing carboxylic acid ligands to react with different metal ion, and obtained11coordination compounds by hydrothermal syntheses technology. These complexes were characterized by IR and C, H, N analysis, determined crystal structures by the X-ray single crystal analysis. We also studied the UV-Vis, fluorescent and thermostability properties of these complexes.1. Five metal-organic complexes were obtained from the hydrothermal method through the2-(pyridine-4-yl)-1H-imidazole-4,5-dicarboxylic acid (H3pydc) ligand, auxiliary ligands (mbm、1,4-H2bdc) with AgNO3, Sm(NO3)3and Dy(NO3)3, namely:[Ag2(Hpydc)]n (1),[Ag2(Hpydc)(mbm)]n (2),{[Sm2(H2pydc)(Hpydc)2(H2O)4] NO3-6H2O}n (3),{[Sm(Hpydc)(OX)o.5H2O]·(H2O)2}n (4),{[Dy2(Hpydc)2(H2O)9]·(H2pydc)2·16H2O}n (5). The complex1crystalizes in the monoclinic with space group Cc. The Ag(I) atom is triangular three-coordinated. A three-dimensional net-like structure is formed because there is a dihedron between the imidazole ring and pyridine ring. And the3D structure with the3,3-connected metal nodes Ag(I), a MOFs with (82.10)(82.10) topology in1creates. Complex2crystallizes in the monoclinic with space group P21/c. A infinite zigzag chains can be obtained when auxiliary ligand(mbm) is coordinated. And Ag(I) have two kinds of coordination model. Complex3crystallizes in the monoclinic with space group P21/n. The asymmetric unit consists of two Sm atoms which link the ligand form a1D chain structure. Complex4crystallizes in the monoclinic with space group P21/c. A3D mesh structure with the3,4-connected metal nodes Sm(III), a MOFs with (4.85)(4.82) topology in4creates. The3D structure is constructued if the dicarboxyl is coordinated into the complex. We hold that the reason of the phenomenon is caused by the high temperature and NaOH. Complex5crystallizes in the triclinic with Cc space group. It is a ID chain. The π…π interaction between imidazole and pyridine made the ID chain into a3D network. And the free ligand occupies the cavity of three-dimensional supramolecular, which we think the occupies are able to increase the stability of the3D network. The UV-Vis indicates that the UV curve-line do not change because of the metal coordination; Fluorescence analysis shows that complexes2has good fluorescence properties; Furthermore, the thermal properties of the complexes have been investigated. The results show that complexes are more stable if they have no crystal water.2. Six isostructural complexes were obtained from the hydrothermal method through5-[2-carboxyl-3-(tetrazol-5-yl)phenoxy]isophthalic (L) ligand with earth metal, namely:{[LnL(H2O)3]-2H2O}n [Ln=La(6), Nd(7), Sm(8), Eu(9), Gd(10)],{[PrL(H2O)3]-H2O}n(11). These complexes all crystallize in the triclinic with P-1space group and exist in two-dimension structure. A3D supramolecular structure is formed through the two-dimension linked via the hydrogen bonds. The UV-Vis indicates that the UV curve-line do not change because of the metal coordination; complex9exhibits strong long wave sensitized emissions typical of Eu3+ion; the TG demonstrates that the complexes have good thermal stability and exhibit potential applications in some aspects.