Synthesis,Structure And Properties Of The Coordination Polymer Constructed By Transition Metal And Flexible Aromatic Polycarboxylate Ligands

It is still challenging for coordination polymers to achieve the structures with desired properties due to many uncertain factors, such as organic ligands, anions, reaction temperature, pH, solvents, and so on. The efforts are significant to understand the relationships between these factors and the diversity of the structures. Flexible polycarboxylate ligands have become attractive as building elements in the synthesis of multidimensional networks, because their conformational freedom can be affected easily by external influencing factors, and may provide more possibility for the construction of coordination polymers with unusual structures.In this thesis, we have synthesized eight coordination polymers based on four flexible polycarboxylate ligands and transition metal. The main results are as follows:（1） Design and synthesis of four flexible polycarboxylate ligands and one N-heterocyclic second ligands: 4,4’-（1,4-phenylenedioxy）dibenzoic acid（H2L1）, 1,4’-（1,4-phenylenedioxy）-dibenzoic acid（H2L2）, 1,3-bis(3,5-（biscarboxyl）phenoxy]-2-hydroxy propane（H₄L₃）, 4,4’,4’’-（（（2,4,6-trimethylbenzene-1,3,5-triyl）tris（methylene））tris（oxy））-1,3-benzenedi-carboxy lic acid（H6L4） and 1,1′-1,4-（butanediyl）bis-benzimidazole（bbbm）. H2L1 and H2L2 are semiflexible polycarboxylate ligands with Ar-O-Ar unit. H₄L₃ and H6L4 are flexible polycarboxylate ligands with isophthalic acid as construction unit. All the ligands are characterized by FT-IR and 1H-NMR.（2） Eight novel coordination polymers, [Mn（L1）（H₂O）2]n（1）, [Cd（L1）（H₂O）2]n（2）, [Zn（L2）（bbbm）0.5]n（3）（bbbm = 1,1′-1,4-（butanediyl）bis–benzimidazole）, [Co（L2）（bbbm）]n（4）, [Cd（L2）（bbbm）]n（5）, [Cu2（L3）（H₂O）3]n（6）, [Cd2（L3）（H₂O）6]n（7） and [Cd2（L4）（H₂O）4]n（8） have been synthesized based on the above ligands. All the compounds are characterized by IR, elemental analysis, powder X-ray diffraction andsingle crystal X-ray diffraction. Besides, thermogravimetric analysis and photoluminescence properties of the mentioned complexes were also investigated in the solid state at room temperature. The temperature dependent molar magnetic susceptibility of complexes 1, 2 and 6 are also tested.（3） Compounds 1 and 2 are isostructural and display a dia 3D geometric structure with vertex symbol of [6（2）.6（2）.6（2）.6（2）.6（2）.6（2）]. Compounds 4 and 5 are isostructural and are constructed by ligands H2L2 and bbbm. They possess 2-fold interpenetrating 2D frameworks with the Schl?fli symbol of {63} and with the polycatenation and polythreading interpenetrating structures. With the point symbol of（44.62）, compound 3 is significantly different from 4 and 5. This difference can be refered to the diversity of metal oin. Meanwhile, different magnetism and luminescence in Compounds 4 and 5 indicate that the metal center may also impact the properties of coordination polymers.（4） Constructed by ligand H₄L₃, compound 6 exhibits 3D infinite chains structure with the Schl?fli symbol of{42.64}{42.84}. Compound 6 not only possesses kagomé layer but also contains bimodal porous structure. The magnetism of compound 6 are also studied. The results indicated the existence of antiferromagnetic couplings among metal centers. Compounds 7 and 8 are constructed by ligands H₄L₃ and H6L4 respectively. They have the same topology with the point symbol of（63）. Compound 7 possesses 2D frameworks with an ABCABC stacking mode. Compound 8 shows similar structure to 7 with an ABAB stacking mode. The luminescent properties of 7 and 8 can make them good candidates for the functional photoluminescent materials.