The Studies On Construction, Characterizations, Properties And Bioactivities Of Coordination Polymers Based On N-containing Multifunctional Ligands

The crystal engineering of supramolecular architectures based on metal and organic building blocks has been rapidly expanding in recent years in chemistry, materials, medicals and biology areas owing to not only their novel topologies and intriguing architectures but also their potential applications in catalysis, electrical conductivity, magnetism, host-guest chemistry, nonlinear optics, molecular recognition, gas adsorption and biological activity. Today, in the realm of supramolecular chemistry, great interest has been focused on the crystal engineering of coordination frameworks by use of the principles of self-assembly. It is demonstrated that considerate designing or selecting rational building block through appropriative assembly strategy should be the key in constructing target polymers and also a stubborn challenging work for scientists.In this research, with the aim of obtaining new materials with beautiful architecture and excellent physical properties, we selected multi-functional N-containing ligands (N-containing dicarboxylate ligands and benzimidazolic ligand) as building blocks to construct coordination polymers with selected transition metal ions guided by assembly principle of coordination polymers crystal engineering after the relative research background is considered. Under different reaction condition, nine coordination polymers have been synthesized. They are listed as follows: [pbb(Hpbb)₂]SO₄·8H₂O (1), [Zn(pbb)₂(H₂O)₄](NO₃)₂·2C₂H₅OH·4H₂O (2), [Zn₂(pbb)₂(μ-OH)(μ-OAc)](OAc)₂·7H₂O (3), [Cd(pbb)₂(H₂O)₄](NO₃)₂·2C₂H₅OH·4H₂O (4), [Cu(pbb)₂(H₂O)₄]Cl₂·2DMF·6H₂O (5), [Co(pbb)₂(H₂O)₄](NO₃)₂H₂O (6), [Ni(pbb)₂(H₂O)₄](NO₃)₂ (7), [Ag₂(bpp)₂(H₂O)]·pydc·7H₂O (8), Cd(pzdc)(μ₂-H₂O)(H₂O) (9).These polymers have been characterized by X-ray single crystal diffraction analysis, elemental analysis, IR spectra, XRPD analysis, thermal analysis and fluorescence spectroscopy to investigate the spectroscopy characters and properties. The results revealed that the conformation of the ligands play an important role in the structure of complexes. Different Zn^â…¡salts induced the creation of different compound complexes 1, 2 and 3. A unusual (H₂O)₁₂ cluster constructed by a chair conformation (H₂O)₆ ring core with a pair of (H₂O)₃ is observed in 1; with the help of strong aromaticÏ€-Ï€interactions, 2 presents 3D supramolecular structures involving 1D open channels encapsulating NO₃^- ions; a eight-membered crown-like rings in 3 are formed via hydrogen bonds between coordinated water, free water molecules and -OH. In 4 and 5, anions participate in the formation of 1D latter-like chain via hydrogen bonds, respectively. Three kinds of oxygen atoms construct a twelve-membered unit by O-H…O hydrogen bonds in 5. The organic blocks are arranged regularly byÏ€-Ï€stacking interactions in 6 and 7. A centre-symmetric (H₂O)₁₂ cluster comprising one (H₂O)₄ ring core and two additional (H₂O)₃ and two dangling monmeric water in 8 is rather unusual. In 3D complex 9, 1D ring-like chain is formed by four-membered Cd₂O₂ units. All of the new and interesting structures contribute to the richness of coordination chemistry and supramolecular chemistry.Additionally, the antimicrobial activities of pbb and 2-7 were investigated by the inhibitory zone test method and microcalorimetry. The results from the inhibitory zone test method indicate that pbb and 2-7 have selective inhibition property for the testing strains. The results from microcalorimetry reveal that pbb and 2-7 can inhibit the growth of E. coli at 37℃. Importantly, the presence of metal ions has improved clearly antibacterial activity of ligand pbb. We believe that this work may contribute basic information to the further application of pbb and its complexes in chemistry, medicals and biology fields.