Skeleton And Properties Of Metal-organic Aromatic Carboxylic Acid Ligands To Build On

Metal-organic frameworks (MOFs) have gained great interests due to their fascinating topologies and wide field of applications as unique optical, distinct magnetic, absorption and catalytic materials. As for self-assemblies of MOFs, the geometries of carboxylate ligand and metal-organic secondary building unit (SBU) are two key factors which decide the topologies of final structures. Accordingly, the various carboxylate ligands have been extensively explored to construct diverse MOFs. Meanwhile, changing the length and shape of ligands, the substituent groups, pH values, and temperatures, introducing different meatals, solvents systems, incorporating mixed ligands are important methods to construct novel MOFs. In this context, ten MOFs were assembled by various approaches. Five isostructural three-dimensional (3D) lanthanide (Ln) frameworks [LnCl(bpdc)(DMF)](Ln=La (1), Ce (2), Pr (3), Nd (4) and Sm (5), H2bpdc=4,4’-biphenyl-dicarboxylic acid, DMF=N,N-dimethylformamide) have been solvothermally synthesized by linear H2bpdc ligand. Two new3D porous frameworks [Co2(bpdc)2(H2bpz)]-2(DMF)-5(H20)(6),[Co2(bpdc)1.5(Hbpz)]-DMF-CH3CN-H2O (7),(H2bpz=3,3’,5,5’-tetramethyl-4,4’-bipyrazole) has been solvothermally synthesized by employing mixed H2bpdc and H2bpz ligands. Another three3D porous frameworks [Mn2Cl(bpdc)1.5(H2bpz)]-6(H2O)(8),[Cd2Cl(bpdc)1.5(H2bpz)]-6(H2O)(9),[Zn3(btc)2(H2bpz)2-(H2O)2]-6(NMP)-4(H2O)(10)(H3btc=1,3,5-Benzenetricarboxylic acid) have been solvothermally synthesized by employing H2bpz and mixed H2bpdc or H3btc ligands, respectively. The structures of complexes have been determined by X-ray single crystal diffraction,.The framework of1-5and8,9all contain an unusual rare earth/transition metal-carboxylate/Cl chains, respectively;6is a2-fold interpenetrated pillared-layer framework based on a binuclear paddle-wheel Co2(O2C-R)4cluster;7is an3-fold interpenetrated5-connected3D framework based on Co2(O2C-R)2(NN) SBUs, which features the fascinating double-walled nanotubes based on nonuple and triple helices. Meanwhile, all complexes have been characterized by power X-ray diffraction (PXRD), elemental analyses, IR spectra and thermogravimetric analysis (TGA). The photoluminescent, magnetic and adsorption properties of some MOFs have also been tested and investigated mainly.