| Metal-Organic Framework(MOFs) materials are receiving more and more attention in recent years, due to their potential applications in many fields, such as catalysis, sensing, gas separation and adsorption, molecule identification, drug transportation, electronics as well as magnetism. Current research mainly focuses on the rational design and synthesis of novel MOFs with unique structures or particular functions. To further explore relationships between syntheses, structures and properties, we selected an S-containing carboxyl ligand, 3,4-dimethyl[2,3-b]thiophene-2,5-dicarboxylic acid(H2DMTDC). Based upon this ligand, a series of coordination polymers were obtained through reactions with transition metals or rare-earth metals under solvothermal conditions. The research includes:1. Transition metal complexes based upon H2 DMTDC and N-containing ligands: syntheses, structures, luminescent and magnetic propertiesSix complexes were solvothermally synthesized, namely, [Zn(DMTDC)(bpt)(H2O)]n(1), {[Zn(DMTDC)(5,5-dmbpy)]·0.5DMF·1.5H2O}n(2), [Zn(DMTDC)(1,3-bimb)]·2DMF·H2O}n(3), [Zn2(DMTDC)2(bpp)]n(4), [Co(DMTDC)(bpe)]n(5), and [Co2(DMTDC)2(bpp)(DMF)2(H2O)]·H2O}n(6)(bpt = 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole, 5,5′-dmbpy = 5,5′-dimethyl-2,2′-bipyridyl, 1,3-bimb = 1,3-bis(imidazol-1ylmethyl)-benzene, bpe = 1,2-Bis(4-pyridyl)ethylene, bpp = 1,3-di(pyrid-4-yl)propane). Complexes 1 and 2 are 1-D linear and zigzag chains with different supramolecular structures. In complex 1, adjacent chains form zipper-like structures through N–H?N interactions. In complex 2, however, chains in adjacent layers are stacked in an unusual unparallel level through C–H?O interactions. Complex 3 features a highly corrugated 2-D(4,4) layer and the layers are penetrated byeach other to give 3-D polycatenations. Right- and left-handed helical Zn-bimb chains are arranged alternately within and between the layers, leading to mesomeric property of the whole network. Complexes 4 and 5 are both two-fold interpenetrating 3-D pillared-layer frameworks based on binuclear Secondary Building Units. In the former, four carboxylate groups adopt syn-syn coordination modes, bridging adjacent Zn atoms to form a paddle-wheel Zn2(COO)4 unit. In the latter, however, four carboxylate groups adopt syn-syn and chelating modes, respectively, bridging Co atoms to form a planar Co2(COO)4 unit. Connection of these units through biphene rings of DMTDC ligands leads to 2-D layer structure. The layers are pillared by bpp or bpe ligands, leading to 3-D frameworks. In complex, 6, one aqua molecule and two carboxylate groups in syn-syn mode bridge Co atoms, generating interesting Co2(COO)2(μ2-H2O) units, which are connected together through biphene rings and flexible bpp ligands, forming 2-D wave-like layers. Luminescent properties of the ligands and compounds in the solid state at room temperature have also been explored. Complex 1 and 3 showed strong luminescent propertie at 435 and 467 nm at room temperature. Moreover, the luminescence intensities of both the ligands and these complexes are largely dependent on the organic solvents. Magnetic measurements indicated antiferromagnetic coupling interactions are present within the binulcear units of complex 5 and 6. Also, significant spin canting and a small magnetization loop was observed in complex 5.2. Lanthanide-Organic Frameworks with double and triple-stranded Inorganic Rod-shaped Building Units Assembled from a thiophene Dicarboxylate acid: syntheses, structures, luminescent, magnetic and sensing propertiesThree series of lanthanide coordination polymers with formula [Ln(DMTDC)1.5(5,5’-dmbpy)]n(type I, Ln = Pr 7, Eu 8), {[Ln4(DMTDC)6(DMF)2]·2DMF·H2O}n(type II, Ln = Y 9, Er 10, Yb 11), {[Ln(DMTDC)1.5(H2O)2]·G·2.5H2O}n(type III, Ln = Y 12, Pr 13, Nd 14, Sm 15, Eu 16, Gd 17, Tb 18, Dy 19, Ho 20, Er 21, Tm 22),have been synthesized by hydrothermal reactions of H2 DMTDC with corresponding lanthanide nitrate in the presence of different N-containing ligands. Different N-containing ligands in the syntheses acted as templates, having significant effects on the resulting architectures. Complex 7 and 8 are isostructual 2-D double-layer structures in which DMTDC ligands connect two neighboring Ln atoms to form Ln2(CO2)4 binuclear units. Complexes 9-11 exhibit porous framework with triple-stranded rod-shaped inorganic building units with interesting composition and arrangement. 1-D nanosized channels are formed along the(1,1,0) and(1,-1,0) axes, respectively. Topologically, the whole framework could be represented as a(4,4,4,4,4,4,4,6,6,6,6)-connected(42·63·8)3(42·64)(43·62·8)2(46·63·86)(46·64·85)(47·67·8)2 topology. Complexes 12-22 are isostructural and possess double-stranded rod-shaped inorganic building units. The whole net is a trinodal(3,4,5)-connected(4·6·8)(42·62·82)(42·63·85)2 network with 1-D triangular channels along c axis. Gas adsorption measurements indicated that complexes 9-22 display moderate adsorption properties towards N2 and CO2. Magnetic measurement revealed that The-ΔSm of complex 17 is 24.5J kg-1K-1 at 2K for ΔH of 70 k G. This value is relatively high, indicative of new molecular magnetic cooler. Complex 19 exhibited field-induced magnetic relaxation. Luminescent properties indicated that complex 16 and complex 18 exhibit characteristic properties and showed fluorescence reliable properties on different organic molecules as well as sensing properties of Cu2+ ion. |
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