Construction And Property Studies Of Metal-organic Frameworks Assembled By Azolecarboxylate Ligands And Transition Metals

During the last decade, metal-organic frameworks(MOFs), as a novel functional material, have gained comprehensive attention, not only because of their diverse topologies, but also potential applications in catalysis, gas storage, chemical separations, nonlinear optics, drug delivery, luminescence, and so on. The interesting architectures of MOFs mainly rely on the assembly of various metals and linkers. Linkers usually employ organic ligands which possess N- or O-donors to design and synthesis. In order to obtain stable and multifarious structures, introducing metal clusters as secondary building units(SBUs) or controlling the interpenetration of the framework have turned out to be the effective methods. The method of designing metal clusters is intensely influenced by many factors, such as the coordination number of metal ions, various ligands, solvent, temperature and the p H of system. Interpenetration usually reduces pore channel and adsorption capacity, but it also can give rise to other properties, for example, interpenetrating construction is in favor of improving its water stability.In this paper, we report the hydrothermal or solvothermal synthesis of eight MOFs based on-N or-COOH organic ligands and metal centers. Compound 1 is a novel 3D framework with trinuclear Cd(II)-clusters. The centers of trinuclear cadmium are occupied by the chlorine anion, the self-assembly of the trinuclear SBUs and ligands form a 2-fold interpenetrated 3D framework with pcu topology. Compound 1 displays good water stability. By virtue of introducing d10 cadmium metal ion, compound 1 possesses good luminescent properties. Compounds 2 and 3 are solvothermally synthesized by using HPZA as organic ligand and DABCO as template. Compound 2 is a 4-fold interpenetrated 3D framework with Cu(II) metal center, possesses good magnetic property. Compound 3 is a 1D chain structure in which DABCO as co-ligand. Compounds 4-8 are assembled from HPAD ligand and transition metals. Compounds 4-7 are isostructural with 1D chain feature, which were further connected by hydrogen bond to form supramolecular polymers. Due to the different metal centers, compounds 4-7 display different properties. Compounds 4 and 5 show luminescent property, while, compounds 6 and 7 exhibit magnetic property. Compound 8 is a novel 3D framework based on trinuclear Cu(II)-cluster SBUs. Compound 8 exhibits more open framework, and is not stable after removal of the guest molecules from, it displays magnetics property.