Structural And Functional Studies Of Metal Organic Frameworks (MOFs) Based On Carboxylic Acid Ligands

"Structure determines the nature and the nature reflects the structure" is the basic role of chemical or even natural science; this rule is equally applicable for structure chemistry, which is an important branch of inorganic chemistry. With the development of the chemistry, people understand the structure of material in-deeply. How to regulate the property successfully by fine-tuning of the structure become a hot spot. In recent years, the rational design and synthesis fnctional Metal-Organic Frameworks (MOFs) became a more and more fascinating field due to their interesting topologies and potential applications in gas adsorption, nonlinear optics, magnetism, luminescence, molecular recognition, etc. The structure feature of metal-organic complexes is adjustable, which is different from traditional molecular sieve. Generally, the construction of MOFs is seriously affected by the bewildering structure-directing factors such as the metal ions, the predesigned organic linkers, solvent, pH value of the solution, the temperature, the counter ion with different bulk or coordination ability, the template and metal-to-ligand stoichiometry, et.al. How to control the reaction conditions of semi-directed synthesis of metal-organic complexes with the target structure of coordination compounds is of great significance.In this paper, we select a series of carboxylic acid ligands to construct a metal organic framework material, including rigid ligand H2LOMe and small ligand H4dbtec. Moreover, the structures and thermal stabilities of1-8and photoluminescence behaviors are discussed based on Zn2+, Cd2+and rare earth ions. There are following four chapters:In chapter one:A brief introduction of the coordination chemistry, crystal engineering, metal-organic frameworks and other basic concepts and principles. Selective focus on the development of coordination Polymers described in a new direction and new ideas. In chapter two, five metal-organic coordination complexes with the formulae of {Mn(L)(H2O)2}n (1),{[Cd1.5L1.5(DEF)2]·2DEF}n (2),[Co1.5(L)1.5(H2O)]n (3),{[Co(L)(H2O)2]·4H2O}n (4), and {[Ni(L)(H2O)2]·4H2O}n (5),(H2LOMe=4,4’-(2,3,6,7-Tetramethoxyanthracene-9,10-diyl)dibenzoic acid) based on a new rigid dicarboxylate ligand were synthesized and structurally characterized. Structural analysis reveals that H2LOMe acts as multibidentate bridging linker to connect metal ions, and possesses similar coordination modes with terephthalic acid.In chapter three, two isostructural lanthanide complexes,[Ln(dbtec)0.5(ox)0.5·3H2O]n,[Ln=Dy (6), Yb (7)](H4dbtec=3,6-dibromobenzene-1,2,4,5-tetracarboxylic acid; H2ox=oxalic acid), have been synthesized under the hydrothermal method and characterized by single-crystal X-ray diffraction, X-ray powder diffraction (PXRD), thermogravimetric analysis (TGA) and elemental analysis (EA) and IR spectra. Complex6and7present a2-nodal (4,6)-connected3D fsc network. The13C NMR of H4dbtec indicates ox in6and7is generated by the in-situ decomposition of H4dbtec.In chapter four, a new cadmium(Ⅱ) organic coordination polymers [Cd(dbtec)0.5(H2O)3]·H2O (8), has been constructed based on3,6-dibromobenzene-1,2,4,5-tetracarboxylic acid (H4dbtec), and characterized by elemental analysis (EA), infrared spectroscopy (IR), powder X-ray diffraction (PXRD), and single crystal X-ray diffraction. In8, μ2-η1:η1and μ4-η2:η2dbtec ligands link four hepta-coordinated CdⅡ ions to form a2D44topological layer structure, which is further connected into an interesting3D network by hydrogen bond and Br…O halogen bond. Moreover, the thermal stabilities, solid ultraviolet spectroscopy and temperature-dependent fluorescent properties of8were investigated.