柔性MOFs材料Cu(BDC)的氨气吸附及可逆转化性能

氨气（NH₃）作为氮肥合成的主要原料和PM_2.5的重要间接来源,在工业生产倡导绿色循环的大势之下,减排与回收是绿色发展的必行之路。基于吸附法具有氨气无相变,富集得到的氨气可以直接与二氧化碳反应合成氮肥（如尿素）的优势,研究了具有可逆转化性质的柔性MOFs材料Cu（BDC）的氨气吸附性能。实验中通过水热法制备了三维致密结构的Cu（BDC）（DMF）,高温加热脱除DMF后晶体结构发生改变,得到了具有一维孔道结构的Cu（BDC）材料,比表面积为535 m²·g^-1,纯氨气的吸附量在一个大气压下高达18.4 mmol·g^-1,高于传统吸附剂以及其他新型的多孔MOFs和COFs等材料,并且通过减压和加热,材料可以逐步实现再生,具有优良的“载氨”特性。直接制备的Cu（BDC）（DMF）也可以在氨气的环境中（DMF被NH₃替代）转变为Cu（BDC）（NH₃）₂,省去了制备Cu（BDC）的过程。     

Amine-directed structural studies of four zinc metal-organic frameworks based on a novel phosphonocarboxylate ligand

A novel phosphonocarboxylic ligand, 4′-phosphonobiphenyl-3,5-dicarboxylic acid (H₄pbpdc), was synthesized to construct 4 zinc compounds, namely, {[Zn₃(pbpdc)₂·2R}_n (R = C₅H₁₂N for 1, C₄H₁₀N for 2 and C₆H₁₆N for 3) and {[Zn₂pbpdc]·C₆H₁₈N₃}_n(4), which were characterized by X-ray crystallography, elemental analysis, FTIR and TG. Structures 1 ~ 3 have the same 3-dimensional (3-D) frameworks with point symbol of {4.6.7³.8}₂{4².6.7².8}₂{4².6².7.8}₂{4².6².7²}. Structure 4 is constructed from a 6-connected metallic cluster and 3-connected phosphonocarboxylic building units resulting in a topology of flu-3,6-C2/c. The luminescent properties of compounds 1 ~ 4 and organic ligand were studied.     

Novel Cd(II) and Co(II) 2-D frameworks based on terephthalate and 1-substitutedimidazole mixed-ligands

The two Cd(II) and Co(II) 2-D frameworks have been prepared by means of self-assemblies of Cd(II) or Co(II) salts and 1-substituted imidazole and terephthalic acid, and structurally characterized by X-ray diffraction analyses. In complex 1 2-D frameworks with rhombic cavity are formed, in which the each top point of rhombus contains one hexa and two heptacoordinated Cd(II). In complex 2 2-D networks with rectangular cavities are formed, and the opposite benzene rings from carboxyls in each rectangular cavity are parallel.     

A novel 3D Nd(III) metal-organic frameworks based on furan-2,5-dicarboxylic acid exhibits new topology and rare near-infrared luminescence property

A rare lanthanide metal-organic framework (Ln-MOFs) based on Nd(III) binuclear nodes, with formula {[Nd₂(H₂O)₃(FDA)₃(CH₃OH)]⋅ CH₃OH}_n (1) (H₂FDA = furan-2,5-dicarboxylic acid), was obtained under solvothermal conditions and characterized by single crystal X-ray diffraction, thermogravimetric analysis and luminescent measurements. 1 has two type of Nd₂ binuclear clusters stabilized by carboxylic groups and exhibits a new topology structure. It is a four nodes 3,3,5,6-connected net with the point symbols of (4.5.6)₂(4.6²)₂(4².5⁴.6².7²)₂(5².6⁶.7⁴.9².10). Moreover, the near-infrared (NIR) luminescence of 1 based on Nd(III) and H₂FDA were investigated in the solid state at room temperature for the first time.     

A novel adenine-based zinc(II) metal-organic framework featuring the Lewis basic sites for heterogeneous catalysis

Metal-organic frameworks (MOFs), as a new sort of crystalline materials, have attracted lots of interest in many applications during the past decades. Recently, many efforts have been focused on the development of MOFs as heterogeneous catalysis. In this communication, we selected adenine (ad) and tetracarboxylic acid, namely 5,5′-(1,3,6,8-tetraoxobenzo[Imn] Li et al. (1999), He et al. (2016) phenanthroline-2,7-diyl)bis-1,3-benzenedicarboxylic acid (H₄L), as organic linkers to assemble with Zn(II) ions to construct a novel adenine-based porous MOF. There are three different inorganic clusters in the framework, including ZnO₂N₂, Zn₂O₂N₆, and ZnO₅N clusters. Interesting, the resultant porous MOF, namely [H₂N(CH₃)₂]⋅[Zn₄(L)_1.5(ad)₃(H₂O)₂]⋅ 4DMF, retains free amino groups in the framework, which can be served as Lewis basic sites to catalyse Knoevenagel condensation reaction. The catalytic study exhibits that the as-synthesized MOF with free amino groups can be used as heterogeneous catalysis with remarkable catalytic efforts and good recycle.     

Highly selective CH2Cl2 fluorescent sensor based on Cd(II) metal-organic framework

Hydrothermal reaction of Cd^2 + ions and 5-(4-carboxybenzyloxy)isoph-thalic acid (H₃L) afforded a new 3D metal-organic framework (Cd-MOF), namely [Cd(HL)(2,2-bipy)]_n·1.25nH₂O. The luminescent properties of Cd-MOF dispersed in different solvents have been investigated systematically, demonstrating unique selectivity for the detection of CH₂Cl₂ via a fluorescence quenching mechanism. The luminescent intensity of Cd-MOF was selectively quenched by Ni^2 + ions.     

Molecularly imprinted polymer based on metal-organic frameworks: synthesis and application on determination of dibutyl phthalate

ABSTRACT

The molecular surface imprinted graft copolymer of metal-organic framework MOF-5 with methacrylic acid were prepared by free radical polymerization with dibutyl phthalate as the template molecule using initiator of azobisisobutyronitrile as adsorption system. The prepared MIPs@MOF-5 were characterized by fourier transform infrared spectroscopy, scanning electron microscopy, Brunner?Emmet?Teller measurements, adsorption isotherms, kinetics and selectivity experiments, which showed higher specificity, sensitivity, stability, and better adsorption performance. The results suggested that MIPs@MOF-5 had two sites of adsorption behavior and can recognize sensitively and selectively the template molecules. Moreover, the MIPs@MOF-5 was successfully applied to the analysis of tap water sample.     

An unprecedented twelve-connected 3D metal-organic framework based on heptanuclear cobalt cluster building blocks

Solvothermal reaction of flexible tetrapodal linker tetrakis[4-(carboxyphenyl) oxamethyl]methane acid (H₄L) with cobalt salt yields a new metal-organic framework [Co₇(L)₃(μ₃-O)₃(DMF)₃]∙(DMF)₁₃(H₂O)₂₅. X-ray crystallography reveals that the structure exhibits a unique 2-nodal (4,12)-connected topology with the Schläfli symbol of (4³³.6³⁰.8³)(4⁶)₃, constructed from heptanuclear cobalt clusters as 12-connected nodes and tetrahedral ligands as 4-connected nodes. Temperature-dependent magnetic susceptibility measurements reveal that the heptanuclear cobalt clusters exhibit antiferromagnetic property.     

Two metal-organic frameworks based on a flexible dithioether spacer with luminescence and sensing properties

Two isostructural metal-organic frameworks, [M₂(4-bpytm)(bdc)₂] [M = Zn (1), Cu (2)] (4-bpytm = bis(4-pyridylthio)methane, bdc = terephthalic acid), were synthesized under hydrothermal reactions. Single-crystal X-ray diffraction analyses have been applied to determine their structures. Furthermore, they are characterized by IR, TG, PXRD, element analysis and PL spectra. Both 1 and 2 showed 3-fold interpenetrated 6-connected pcu topologies based on bimetallic tetracarboxylate units with one-dimensional channels. The luminescence properties of 1 are investigated systematically due to its one dimensional channels. The results show that 1 has the ability to sense explosives and inorganic ions.     

Hydrogen adsorption on metal-organic framework (MOF-5) synthesized by DMF approach

Metal-organic frameworks (MOFs), especially MOF-5, are believed to be promising new porous materials for hydrogen adsorption. A comparative study of material synthesis, characterization and hydrogen adsorption was performed to examine the effects of different synthesis conditions on crystal structure, pore textural property and hydrogen adsorption performance of MOF-5 materials. Three MOF-5 samples synthesized with dimethyl formamide (DFM) as solvent and slightly different procedures have shown similar phase structure and chemical composition, diverse crystal structures, varying pore textural properties and different hydrogen adsorption performance. It was established from the experimental results that higher order of crystallinity in the MOF-5 materials generates better adsorbents with larger crystal size, higher specific surface area, uniform pore size distribution (PSD), larger hydrogen adsorption capacity and faster hydrogen diffusion rate in MOF-5 adsorbents. The best MOF-5 sample synthesized in this work (MOF-5(γ)) has a Langmuir specific surface area of 1157 m²/g; it can adsorb 0.5 wt.% of hydrogen at 77 K and 800 mmHg; and results in hydrogen diffusivity inside MOF-5 crystal of 2.3 × 10⁻⁹ cm²/s. The density functional theory reasonably predicts the presence of mesopores and macropores in all three MOF-5 samples synthesized in this work.     

3-D supramolecular frameworks assembled by lanthanide binuclear molecules based on 1,2-phenylenedioxydiacetic acid and 1,10-phenanthroline

The complexes [Ln₂(PDOA)₃(phen)₂(H₂O)₂] · 2H₂O (Ln = Eu (1), Tb (2), and Dy (3); H₂PDOA = 1,2-phenylenedioxydiacetic acid; phen = 1,10-phenanthroline) have been synthesized and structurally characterized by single crystal X-ray diffraction methods. The three complexes are all binuclear molecules. The two Ln(III) centers are linked by only one PDOA ligand through its two bidentate-chelating carboxylate groups. PDOA also acts as a terminal ligand using one carboxylate oxygen and ether oxygen atoms to chelate the Ln(III) ion. 3-D supramolecular frameworks are built up by the hydrogen bonds and π–π stacking interactions. The fluorescent spectra of the three complexes show the characteristic emission of the Eu(III) for 1, Tb(III) for 2, and Dy(III) for 3, respectively.     

A novel 2, 6-connected inorganic-organic 3-D open framework based on {As2Mo18} with photocatalytic property and anticancer activity

A new inorganic-organic open framework based on Wells-Dawson arsenomolybdate, {Ag(diz)₂}₃[{Ag(diz)₂}₃(As₂Mo₁₈O₆₂)]∙H₂O (1) (diz = 1,2-diazole) has been hydrothermally synthesized and characterized by elemental analysis, IR, TG, UV, XRD, and single-crystal X-ray diffraction. In compound 1, each {As₂Mo₁₈} cluster uses six terminal oxygen atoms on 'equator' position to attract peripheral six {Ag(diz)₂} linkers, which are further connected by six Dawson clusters located on two different planes via unique equator-to-equator interlaced ways to form a unprecedented 3D network with {8¹² ∙ 12³}{8}₃ topology. Compound 1 represents the highest covalent connectivity of 3-D Dawson arsenomolybdate, which exhibits merit photocatalytic properties for degradation of refractory dyes Azon Phloxine (AP) under UV light. In addition, compound 1 has a potent inhibition effect on proliferation of Human gastric adenocarcinoma cells (SGC-7901).     

A new three-dimensional 4,8-connected inorganic open framework based on manganese phosphomolybdate with (41261284) (46)2 topology

A new inorganic open framework based on manganese phosphomolybdate, (C₂N₂H₁₀)₄{Mn₃[P₄Mo₆O₂₆(OH)₅]₂}·6H₂O (1), has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR spectroscopy and TG analysis. Single-crystal X-ray diffraction analysis reveals that compound 1 exhibits a 4,8-connected three-dimensional inorganic open framework with (4¹²6¹²8⁴) (4⁶)₂ topology and possesses three-dimensional channels filled by the protonated H₂en ligands and water molecules. Additionally, DC susceptibility measurement shows the antiferromagnetic character of the exchange interactions in compound 1.