Design, Synthesis And Characterization Of Aromatic Carboxylic Acid Metal - Based Skeleton Materials

In this paper, we have designed and synthesized ten new metal-organic frameworks based on transition metals Cd(II) by choosing semi-rigid or rigid organic ligands with carboxylate groups,4,4’,4"-((benzene-1,3,5-triyltris(methylene))tris(oxy)) tribenzoic acid (H3L, C33H30O9), H3BTC(C9H6O6), and using as alkali metal ions as templates under solvothermal or solvent vapor conditions. They were characterized by X-ray, FT-IR, TGA and elemental analysis. We also investigated their optical and adsorption properties.Transition metal Cd(II) organic carboxylate frameworks, Cd(C33H27O9)(C3H7NO)(C2H8N)·0.5H2O (1),[Cd(C33H28O9)(H2O)2]·(C3H7NO)(2),[Cd2(C33H27O9)2Na2(H2O)7](3),[Cd(C33H27O9)]·(C2H8N)·(H2O)(4), have been synthesized under solvothermal conditions. X-ray diffraction analyses reveal that compound1crystallizes in monoclinic space group C2/c, which shows six-fold interpenetration3D structure with ThSi2topology, while compounds2-4exhibit two-dimensional (2D) architectures and crystallize in triclinic symmetry space group P-1. In compound3and4, their structures are built up from inorganic and organic3-connected building units, whose Schlafli symbols are63.[Cd3(C9H303)4Na6(H2O)10]·2H2O (5),[Cd3(C9H3O3)4Na(H2O)8](6),[Cd3(C9H3O6)3]·(NH4)3·(H2O)5(7),[Cd(C9H306)(H20)3]-(C2NH8)(C3H7NO)(8), Cd2(C9H3O6)2K2(H2O)4(9),[Cd3(C9H3O6)3Rb5Br2](10) have been synthesized by reaction of Cd(II) with H3BTC in a mixed solution of DMF and H2O. They exhibit three-dimensional (3D) architectures. Compound5is bcu-x net based on octahedral cages. Both compound7and compound8are negative frameworks, which could be anticipated as potential ion exchange materials. In compound6or compound9together with compound10, carboxylate ligand (H3BTC) exhibit unexpected high coordination models, even connecting metals up to11which are rare.The optical and adsorption properties of these compounds have been investigated and the results reveal that they could be anticipated as potential fluorescent materials. Compound5could also be used as adsorption materials.