Preparation And Characterization Of N-contaning Organic Ligands Based Metal-organic Coordination Polymers

The metal organic polymers are organic-inorganic hybrid materials which areconstructed based on the assembly of metal ions and multifunctional organic ligandsvia coordination bond，π-π stacking interactions，weak hydrogen bonds etc. Theorganic ligands can be classified as carboxylate ligands and N-containing heterocycleligands base on the type of coordination atoms. Metal–organic coordination materialshave attracted wide scientific attention not only owing to their structure prediction andmodification but also to their potential application in many areas such as fluorescence,magnetism, catalysis, gas separation and storage.In this article three sets of the synthetic system were successfully designed toobtain eight kinds of metal-organic compound by reactions of the corresponding metalsalts with ligands. Their structures were characterized by elemental analyses, IR, TGand single-crystal X-ray diffraction analysis.The coordination polymer1-4was accomplished using transition metal ions withthe mixed ligands malonate and1,3-bis（4-pyridyl）propane（bpp）. Among them,1-3wasobtained using solvent evaporation method and4was synthesized under hydrothermalcondition. In compound [Zn（C13H14N2）Cl2]（1）, each bpp molecule bridge twoindividual ZnⅡions to form1D undulate structure. Through weak offset π-π stackinginteractions and C-H…π interaction，1D undulate structure is extended to3D structure.For [Cu（C₃H₂O₄）₂](C₁₃H₁₆N₂)₃（H₂O）₂（2）, in the bc plane, the2D Square-grids with adiameter of6.3308*6.3308are created through the bridges of malonate.Furthermore, protoned1,3-bis（4-pyridyl）propane（bpp） serves as templates for pillaringthe2D Square-grids to form3D structure though hydrogen bonds. Interestingly,2features trimeric water clusters connected by hydrogen bonds. For [Cd₂（C₃H₂O₄）₂（H₂O）₄]（3）, malonate molecules bridge Cd atoms to create peach-shaped and rectangulargrid. The coordination polymer [H₂N（CH₃）₂][Co（HCOO）₃]（4） was synthesized underhydrothermal condition by using Co（AC）2/1,3-bis（4-pyridyl）--propane/malonate in themixed solvent DMF/H2O at140℃for3days. The single-crystal X-ray analysis showsthat the malonate molecules decompose into formic acid Molecules and the DMFmolecules break down to Dimethyl amine ions. Finally they assemble into3Dframeworks with the α-Po topology.The coordination polymer5-7was accomplished by slow evaporation technique using ZnⅡ/CuⅡ/CdⅡions with the mixed ligands malonate and Triethylenediamine.[Zn（C₃H₂O₄）_0.5(C₆H₁₂N₂)H₂O]n（5） and [Cd（C₃H₂O₄）_0.5(C₆H₁₂N₂)H₂O]（7） bothbelong to the Orthorhombic space group. In their structure, triethylenediaminemolecules pillar the two-dimensional structure to form3D structure. Along the a axis,in the bc plane, malonate molecules bridge ZnⅡand CdⅡto form2D square-grids witha diameter of5.4822*5.4822and6.6673*6.6673individually. Triethylenedia--mine act as pillars between layer constructed by malonate and transiton metal ionswith the inter-layer distance of7.0475and7.3462respectively. Along the a axis, inthe bc plane, The structure is further simplified by topology analysis which indicates a3-connected honeycomb net with a Schl fli symbol of63. For{[Cu（C₃H₂O₄）C₆H₁₂N₂)]NO₃}（6）, triethylenediamine act as monodentate ligand withonly one of its two N atoms to coordinate with CuⅡ, and the triethylenediaminearranges in the UDUD stacking sequence. The free NO3-anions are embeded in thestructure via hydrogen bond interactions. Moreover, the magnetic behavior of6wascharacterized in the terms of magnetic susceptibility under10KOe in the temperaturerange of3-300K. The hysteresis loop was obtained under3K in the magnetic intensityof-60KOe-60KOe. The complex6is paramagnetic.The coordination polymer [Ag(C₆H₁₂N₂)（C₇H₈O₃S）]（8） has been synthesizedbased on p-toluenesulfonic acid（tos） and1,3-bis（4-pyridyl）propane（bpp） with AgNO3by slow evaporation method at room temperature. It consists of1D wavelike chains-Ag-bpp-Ag-bpp，and the neighbor chains are bridged via weak Ag-Ag interactions toform2D structure. Thought simplify the bpp and tos as nodes, the frameworks can bedescribed as beautiful crane shaped space packing diagram using diamond software.