Syntheses And Structural Characterization Of Hetero-metal Coordination Polymers With Pyrazine Carboxylic Acid

The rigid ligands of multifunctional carboxylic acid with hetero atoms are one of the preferred choices for hetero-metal complex-preparing. Pyrazine carboxylic acid is a multifunction ligand with N/O-donors and could be employed in linking different metal atoms with different coordinative modes, resulting in unexpected structural hetero-metal polymers. In this dissertation, on one hand,5-methylpyrazine-2-carboxylic acid (Hmpca) is selected as the complex-ligand, six3d-4f, one3d-3d and one3s-3d hetero-metal coordination polymers were obtained and structurally characterized. On the process of preparation of hetero-metal complexes with copper complex-ligand, there exits crystal transformation between six types of products and complex-ligands based. On the other hand, pyrazine-2,3-dicarboxylic acid monoamide was selected as the material and assembled with rare-earth metals and copper metal resources under hydrothermal condition.15Rare earth (RE)-copper hetero-metal coordination polymers were obtained and their motifs and functional properties were also discussed.In the first part, one2D corrugated plane hetero-metal coordination polymer was constructed by Ni(II) complex-ligand and AgNO3in solution reaction. Seven1D or2D hetero-metal complexes (2)-(8) were prepared based on Cu(II)-complex-ligand and RE/main group metal ions in water. Structural analysis indicates that (2)-(3) and (5)-(8) are isostructural. The pH and the types of alkali are critical roles on the resultant products, the employment of NaOH or LiOH, CsOH and RsOH in modulating pH values did not result in any hetero-polymers products. However, a new2D Cu-K complex (4) was obtained in the presence of KOH, in which the Cl-balances the charge and serves as the template.In the second section,15RE-Cu coordination polymers with pyrazine-2,3-dicarboxylic acid are formed under hydrothermal condition. Single crystal diffraction indicates the15complexes are assigned to two types of isostructural motifs. All the compounds were characterized by elemental analysis and IR, etc. The pyrazine-2,3-dicarboxylate (pzdc2-) adopts μ2-η2:η1mode and connectes Cu(II) atom into1D double chain, while it links three RE atoms via μ2-η2:η1fashion into a2D (4,4) grid network. Finally, the structure can be described as the3D brick-like{4.62}2{42.62.82}{63}2{65.8}2topology. Shaler formula calculation shows that its average diameter crystallite size is46.6nm micro-particles. The fluorescence emission spectra of Eu-Cu,Tb-Cu,Sm-Cu and Dy-Cu complexes are also investigated.In the last, a new compound [Cu(mpca)2](25) with5-methylpyrazine-2-carboxylic acid was obtained in CH3OH.[Cu(Hmpca)2(H2O)2]·2NO3·2H2O (26) was diretcly obtained by [Cu(mpca)2(H2O)]·3H2O and La(NO3)3under mild conditions. While a new {[Cu(mpca)(μ-Cl)(H2O)]·H2O}n (27) compound was also prepared via RECI3and [Cu(mpca)2(H2O)]·3H2O in the presence of NaOH.(25)～(27) and (2)～(8) complexes exit single crystal transformation between the resulting compounds and complex-ligand matrix, in which water media induces the break of bond-bond formation and generate crystal transformation.