Syntheses, Crystal Structures And Properties Of The Coordination Polymers Constructed From Carboxylic And N-containing Conjugated Ligands

Coordination polymers are constructed from metal ions and multifunctional organic ligands through coordination bond. In recent years, they have attracted chemist’s attention due to their prospective applications in the areas such as magnetic materials, catalysis, gas storage and separation, photoelectron materials. The coordination polymers constructed from the mixed ligands of carboxylic acid and N-containing conjugated ligands will present some unique structural topology and interesting physical properties.In this thesis, three N-containing conjugated ligands such as3,6-bis（4-pyridyl）-1,2-diazine（bipydz）, 1,2-bis（4-pyridyl）ethyne)（BPYETE）, and dimethyl-3,6-di（4-pyridyl）-4,5-pyridazinedicarboxylate have been used with the carboxylic ligands for preparation of the coordination polymers. The reaction of the Zn（II）, Cd（II） or Co（II） with the above mixed ligands afforded seven coordination polymers. All compounds were characterized by single-crystal X-ray diffraction,thermogravimetric analysis and IR spectra. The gas adsorption of compound 5 has been tested. The fluorescence properties of compound 3 and 6 have been studied.Moreover, the magnetic properties of compound 7 have also been studied. The formulas of these compounds are listed below.{[Cd3（SIP）₂（bipydz）₃（DMF）₂]（DMF）₄（H₂O）₂}_n（1）（H3SIP: 5-sulfoisophthalic acid;bipydz: 3,6-bis（4-pyridyl）-1,2-diazine）{[Zn（5-OH-ophth）（bipydz）]（DMF）₃}_n（2）（5-OH-ophth: 5-hydroxyisophthalicacid）{[Cd（SA）（bipydz）]}_n（3）（SA: succinic acid）{[Zn₃（BPDC）₃（BPYETE）]（DMF）₂（H₂O）₃.5}_n（4）（BPDC: 4,4’-biphenyldicarboxylic acid; BPYETE: 1,2-bis（4-pyridyl）ethyne）{[Co3（BPDC）₃（BPYETE）]·x（solvent）}_n（5）{[Cd2（1,3-BDC）₂（DMF）₂]·x（solvent）}_n（6）{（Me2NH₂）₄[Co（SIP）₂]（DMF）₂（H₂O）₃}_n（7）Four chapters are presented in this thesis.The first chapter has mainly reviewed the concept, synthesis methods, the applications of the metal-organic frameworks, the latest research progress on metal-organic frameworks constructed from N-containing conjugated ligands.The second chapter described the syntheses and structures of the threemetal-organic coordination polymers 1, 2 and 3 constructed from3,6-bis（4-pyridyl）-1,2-diazine and carboxylic ligands. We found that Cd（Ⅱ） ions are linked by 5-sulfoisophthalate ligands to form a two-dimensional layer, which are further linked by bipydz ligands to form a three-dimensional structure in compound 1.Compound 2 has a two-dimensional structure wherein the bipydz bridge the Zn-5-hydroxyisophthalic chains. Cd（Ⅱ） ions are linked by succinic to form a two-dimensional layer, which are further linked by bipydz ligands to form a three-dimensional structure in compound 3. In these compounds, the low-dimensional structures are connected by the 3,6-bis（4-pyridyl）-1,2-diazine ligands to give the high-dimensional structure, which indicates that the 3,6-bis（4-pyridyl）-1,2-diazine bridge is an important connector. Finally, the fluorescence property of 3 has been investigated.The third chapter described the syntheses and structures of the 1,2-bis（4-pyridyl）acetylene ligand and three metal-organic coordination polymers 4, 5 and 6 based on the 1,2-bis（4-pyridyl）acetylene and carboxylic acid. We found that metal ions are linked by 4,4’-biphenyldicarboxylic acid to form a two-dimensional layer, which are further linked by 1,2-bis（4-pyridyl）acetylene ligands to form a three-dimensional structure in compounds 4 and 5. Compound 6 has a two-dimensional structure formed from isophthalic ligand and Cd（Ⅱ） ions wherein the 1,2-bis（4-pyridyl）acetylene ligand was not incorporated into the compound 6. The gas sorption properties of the MOFs 5 on N2,CO2 and paraffin gases have been extensively studied. The compound5 takes up N2、CO2 and C2H₂. Furthermore, the fluorescence property of 6 has been investigated.The forth chapter described the synthesis and structure of the metal-organic coordination polymers {（Me2NH₂）₄[Co（SIP）₂]（DMF）₂（H₂O）₃}_n（7）. The structural analysis showed that Co（II） ions are linked by carboxylate groups of the SIP3- ligands to give a 2D [Co（SIP）₂]4- layer. The anionic 2D layer is charge balanced by the guest[Me2NH₂] + cations. Furthermore, the magnetic properties of 7 have been investigated.The result showed that the presence of significant anisotropy and/or low-lying excited states effect associated with the Co（II） ions are observed in compound 7. However, no slow magnetic relaxation behaviour is observed for 7.The last chapter is the conclusion and an outlook on this thesis.