| Metal-organic frameworks(MOFs),a class of metal-organic hybrid materials,consists of metal ions and organic ligands.Compared to the traditionally porous materials(such as zeolite and activated carbon),MOFs usually exhibit ultrahigh porosity and surface area,special structure and channels,which makes them possesses potential applications in gas adsorption and separation,fluorescence properties,thermodynamic stability,dye sorption and so on.Based on the unique structures and properties of MOFs,our group have designed and synthesized multiple porous materials,further researched the corresponding gas adsorption,fluorescence and dye adsorption of the as-synthesized materials.The contents and results are detailed as follows:(1)A novel porous coordination polymer based on a Co-nitroimidazolate-dicarboxylate pillared-layer network,namely,[Co7(bdc)6(nIm)2(H20)6]·3H2O·3DMF,(1,H2bdc = 1,4-benzenedicarboxylic acid,nIm = 2-nitroimidazole),has been synthesized by a solvothermal reaction.The microporous layers of 1 consisted of two kinds of SBUs,six-connected Co3(O2CR)6 and three-connected[Co2(O2CR)3]+,forming unprecedented Co3-Co2-bdc-based layers with three types of diamonded grids in the be plane.The layers are further linked by bidentate-bridging nIm ligands as pillars into a 3-D MOFs with two kinds of rectangular channels parallel to the c axis.It is worth mentioning that compound 1 also exhibits uniquely polyhedral cages with a maximum diagonal dimension of up to 31.019 A,which has fallen in the scope of mesoporous(2-50 nm).To systematically evaluate the channels and special cages,the adsorption ability of 1 was measured by N2,H2 and CO2 sorption experiments.Topological analysis indicates that the compound adopts a new topological structure with a point symbol of {412·614·82}{46}2.Moreover,thermal gravimetric analysis(TGA)of as-synthesized 1 reveals a stability ranges up to 311 ℃.(2)Two 2-D microporous metal-organic frameworks,[Zn(BDC)(MbIm)]·2DMF(2)and[Cd3(BDC)3(MbIm)2(DMF)2]·2DMF(3),have been synthesized by solvothermal reaction of 1,4-benzenecarboxylic acid(H2BDC)and 2-methylbenzimidazole(MbIm)with Zinc/Cadmium nitrate.Single crystal X-ray diffraction analysis indicates that complex 2 consists of the well-known zinc paddle-wheel motif which is linked by bridging dicarboxylates to form a 2-D square grids.The 2-D layers stack in a biggish offset due to the effect of the spatial structure of MbIm ligand and hydrogen-bonding interaction between MbIm and guest molecules.Similarly,complex 3 is constructed by six-connected Cd3(μ-O2CR)6(MbIm)2 units and bridging carboxylates,resulting in a 2-D layer structure with triangular grids.Topology analysis reveals that complex 2 exhibits a 2-D tetragonal plane network with {44.62} topology symbol,while complex 3 possesses a 6-connected {36.46.53} topological network.An analysis of the luminescence spectra demonstrates that the complexes have good luminescent intensities with greater red-shift(82nm for 2 and 69nm for 3)corresponding to the free MbIm ligand.In addition,elemental analyses,infrared spectra(IR),powder x-ray diffraction(PXRD),and Thermogravimetric analyses(TGA)of complexes 2-3 have been also investigated.(3)Based upon the typically hydrogen-bonded network,[In8(HImDC)12].(DMF)6(HIMDC = 4,5-imidazoledicarboxylate)with ACO zeolite-like topology,iso-reticular[Ing(AImDC)12]·6H2O(4,AImDC = 2-amino-4,5-imidazoledicarboxylate)was synthesized by in situ hydrolysis of the precursor 2-amino-4,5-dicyanoimidazole(ADCIm)with In(NO3)3·H2O in solvothermal condition,exhibiting very high CO2 and H2 adsorption capacities and exceptional thermostability.It is interesting that rational modification of inner surface of channels in prototype MOC-2 with amino groups not only enhances the polarity of the framework,but also doesn’t reduce surface area obviously,which is very rare in functionality of iso-reticular MOFs.Remarkably,the material shows an outstanding gas storage capacity with CO2 uptake capacity of 135.8 cm3/g at 273 K/latm and H2 uptake as high as 2.03 wt%at 77 K/1atm. |
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