Synthesis, Structures And Characterization Of Novel Metal-Organic Frameworks

In the past decade, a huge number of metal-organic frameworks (MOFs) have been reported and attracted much attention of chemists for their variety of fascinating structural topologies and tremendous potential applications, such as gas storage, chirality, luminescence, magnetism, catalysis, nonlinear optics. Possessing similar porous phases to inorganic zeolites, metal-organic frameworks which have rigid open frameworks are called zeolite-like materials. Furthermore, they possess more predominance than traditional inorganic zeolites in gas sorption and store. It is already very important part in these region that to select proper metal central ions and organic ligands to construct metal-organic frameworks and made the object products with the prospective applications in luminescence, electrics, magnetism, molecular recognization, catalysts and so on.We have focused our study on the methods of synthesis, structures and topology of MOFs with multifunctional properties. The aim of investigation is to give MOFs new properties as optics, adsorption, magnetism etc by change metal centers and organic ligands. In this dissertation, we chose two different organic ligands with differernt shape and synthesize five new MOFs, analyzed their single crystal structures and characterized their multifunctional properties. The results mostly include two aspects as follow:(1) The strategy of design ligands is very important in syntheses of MOFs. V-shaped dicarboxylates, as an important family of multidentate and multifunctional O-donor ligands, which have various building modes, have been widely used in synthesizing new MOFs. In the range of V-shaped dicarboxylates, 4, 4'-sulfonyldibenzoic acid (H2sdba) is used scarely. And most of MOFs contained it are 1D or 2D, only a few of them are 3D. Among them, most three-dimensional (3D) MOFs have been reported focused on homometallic 3D coordination polymers, whereas the heterometallic MOFs have been paid much less attention. Herein, we used 4,4'-sulfonyldibenzoic acid as a ligand, and synthesized a 3D heterometallic MOFs Zn2Co(sdba)3(DMA)2(DMA)(H2O)2 (1) Then we used the single Zn(NO3)2·6H2O or Co(NO3)2·6H2O to directly replace the mixture of Zn(NO3)2·6H2O and Co(NO3)2·6H2O with controlled stoichiometry, and obtained two homometallic isostructural MOFs Zn3(sdba)3(DMA)2·(DMA)(H2O)2 (2) and Co3(sdba)3(DMA)2·(DMA)(H2O)2 (3). And we chose Mn(NO3)2 to synthesize a new MOFs [Mn4(SDA)4(DMF)4]·(2DMF·3H2O) (4) with two 1D chains in DMF solvent,and research the stability,fluorescence,magnetism,adsorption etc of compound (1)-(3). Further characterized by single-crystal X-ray diffraction analyses,X-ray powder diffraction, elemental analyses, IR spectra, and TG analyses. The results show that they are isostructural and feature three-dimensional (3D) networks with pcu topology. Furthermore, the photoluminescent and magnetic properties of these compounds have been investigated. Compounds (1) and (2) display strong fluorescence properties at room temperature. Magnetic measures show that compounds (1) and (3) have paramagnetic properties.(2) It is indispensable that the adjustment and oriented synthesis of inorganic - organic framework for MOFs. So, rigid ligands have often be used. In our work, we mainly concentrated on acetylenedicarboxylate acid (ADC) because this is one of the simplest linker and has a carboncarbontriple bond would confere additional stability tothe framework., which can be used for the synthesis of coordination polymers. It has a rigid carbon backbone with two coordinating carboxylate groups. Thus, it is predestined to investigate the underlying mechanisms and interactions that lead to the formation of a specific structural arrangement. As ADC decomposes under the conditions typically used in solvothermal reactions.Therefore, we use slow evaporation of the solvent, diffusion methods to synthesize a 3D new MOFs Zn2(ADC)4(DMF)5(5) . X-ray crystallography reveals that compound (5) crystallizes in space group P2(1)/n and consists of a 3D open framework with ThSi2 topology, and the schafli symbol is {10^3}. Thereby, a 3D extended network is generated with a square channel with dimensions of ca. 9.2×9.2?2 viewed along the [001] directions. TGA were performed to checkout the thermal stability of the compound (5). Decomposition of structure.at 218°C. Solid-state compound (5) showed strong fluorescence properties at room temperature. The strongest emission peak for free H2sdba is at 455nm with excitation peak at 387nm.