10 research outputs found

    Solvent-Controlled Syntheses, Structure, and Magnetic Properties of Trinuclear Mn(II)-Based Metal–Organic Frameworks

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    Solvothermal reactions of manganese­(II) salts with hexa­[4-(carboxyphenyl)­oxamethyl]-3-oxapentane acid (H<sub>6</sub>L) afforded a family of porous metal–organic frameworks, namely, Mn<sub>3</sub>(L)­(DMA)<sub>4</sub>·2DMA (<b>1</b>, <i>C</i>2/<i>c</i>), Mn<sub>3</sub>(L)­(H<sub>2</sub>O)<sub>2</sub>(DMF)<sub>2</sub>·8DMF (<b>2</b>, <i>Cc</i>), and Mn<sub>3</sub>(L)­(H<sub>2</sub>O)<sub>2</sub>(DMF)·4DMF (<b>3</b>, <i>P</i>2<sub>1</sub>/<i>c</i>). All compounds have been characterized by elemental analysis and thermogravimetric analysis and structurally confirmed by single-crystal X-ray diffractions. Their structures consist of three types of trinuclear Mn<sup>II</sup> subunits, which are further bridged by the carboxylic ligand, resulting in two types of topological nets (pts and sra). All of the Mn<sup>II</sup><sub>3</sub> subunits are terminally coordinated by solvent molecules. The structure of the Mn<sup>II</sup><sub>3</sub> core in <b>1</b> is symmetric with an inversion center, whereas those in <b>2</b> and <b>3</b> display a symmetry-breaking phenomenon. Their magnetic behaviors exhibit interesting variations, in which the local net magnetization at low temperature increases gradually from <b>1</b> to <b>3</b>. Such magnetic evolution behavior in trinuclear subunits has never been observed previously

    Construction of Three-Dimensional Cobalt(II)-Based Metal–Organic Frameworks by Synergy between Rigid and Semirigid Ligands

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    Solvothermal assembly of Co­(II) ion, a semirigid tetrahedral carboxylate ligand tetrakis­[(4-carboxyphenyl)­oxamethyl]­methane acid (H<sub>4</sub>L), and rigid linear bidentate linker 1,4-di­(1<i>H</i>-imidazol-1-yl)­benzene (dib) or 4,4′-di­(1<i>H</i>-imidazol-1-yl)-1,1′-biphenyl (dibp) yields four novel metal–organic frameworks (<b>1</b>–<b>4</b>) with different topological connections. [Co<sub>2</sub>(L)­(dib)]·3DMF (<b>1</b>) is a 2-fold interpenetrating <i>sqc</i>422 network and contains 3-dimensional interconnected channels along [100], [010], and [110] directions; [Co<sub>4</sub>(L)<sub>2</sub>(dib)<sub>3</sub>(H<sub>2</sub>O)<sub>4</sub>]·4H<sub>2</sub>O (<b>2</b>) is a three-dimensional 3,4,4-connected new topology with 5-fold interpenetration; [Co<sub>2</sub>(L)­(dibp)]·5DMF (<b>3</b>) and Co<sub>2</sub>(L)­(dibp)<sub>2</sub> (<b>4</b>) are formed in the presence of dibp linker; they feature three-dimensional novel topologies based on 4,6-connection and 4,4-connection, respectively, and no interpenetration is observed. It is demonstrated that interpenetration is accessible simply by changing auxiliary ligands and solvents. Magnetic studies reveal that complexes <b>1</b> and <b>3</b> exhibit antiferromagnetic behavior

    Construction of Three-Dimensional Cobalt(II)-Based Metal–Organic Frameworks by Synergy between Rigid and Semirigid Ligands

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    Solvothermal assembly of Co­(II) ion, a semirigid tetrahedral carboxylate ligand tetrakis­[(4-carboxyphenyl)­oxamethyl]­methane acid (H<sub>4</sub>L), and rigid linear bidentate linker 1,4-di­(1<i>H</i>-imidazol-1-yl)­benzene (dib) or 4,4′-di­(1<i>H</i>-imidazol-1-yl)-1,1′-biphenyl (dibp) yields four novel metal–organic frameworks (<b>1</b>–<b>4</b>) with different topological connections. [Co<sub>2</sub>(L)­(dib)]·3DMF (<b>1</b>) is a 2-fold interpenetrating <i>sqc</i>422 network and contains 3-dimensional interconnected channels along [100], [010], and [110] directions; [Co<sub>4</sub>(L)<sub>2</sub>(dib)<sub>3</sub>(H<sub>2</sub>O)<sub>4</sub>]·4H<sub>2</sub>O (<b>2</b>) is a three-dimensional 3,4,4-connected new topology with 5-fold interpenetration; [Co<sub>2</sub>(L)­(dibp)]·5DMF (<b>3</b>) and Co<sub>2</sub>(L)­(dibp)<sub>2</sub> (<b>4</b>) are formed in the presence of dibp linker; they feature three-dimensional novel topologies based on 4,6-connection and 4,4-connection, respectively, and no interpenetration is observed. It is demonstrated that interpenetration is accessible simply by changing auxiliary ligands and solvents. Magnetic studies reveal that complexes <b>1</b> and <b>3</b> exhibit antiferromagnetic behavior

    Rational Assembly of Co/Cd-MOFs Featuring Topological Variation

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    Three different carboxylate ligands of 4,4′-biphthalic acid (<b>H</b><sub><b>4</b></sub><b>L</b>, linear), 4,4′-axydiphthalic acid (<b>H</b><sub><b>4</b></sub><b>L</b><sup><b>O</b></sup>, V-shaped), and thiophene-2,5-dicarboxylic acid (<b>H</b><sub><b>2</b></sub><b>L</b><sup><b>S</b></sup>, V-shaped and heteroatomic ring) were selected as two-connected nodes to react with Co­(II) or Cd­(II) nitrates in the presence of 1,3,5-tris­(1-imidazolyl)­benzene (<b>tib</b>, Y-shaped and tridentate). Hydrothermal reactions in distilled water afforded seven new Co­(Cd)-MOFs, namely, M­(<b>tib</b>)­(H<sub>2</sub>L)­(H<sub>2</sub>O)<sub>2</sub>·H<sub>2</sub>O (M = Co, <b>1</b>; Cd, <b>2)</b>, M<sub>2</sub>(<b>tib</b>)<sub>2</sub>(H<sub>2</sub>L<sup>O</sup>)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub> (M = Co, <b>3</b>; Cd, <b>4</b>), Co<sub>2</sub>(<b>tib</b>)­(L<sup>O</sup>)·H<sub>2</sub>O (<b>5</b>), Co­(<b>tib</b>)­(L<sup>S</sup>)·2H<sub>2</sub>O (<b>6</b>), and Cd­(<b>tib</b>)­(L<sup>S</sup>)·3H<sub>2</sub>O (<b>7</b>). Of particular interest, they exhibit four interesting nets. <b>1</b>–<b>2</b> and <b>3</b>–<b>4</b> feature binodal (3,4) and (3,3,4,4)-connected nets if H-bonds are taken into account, respectively. <b>5</b> is composed of a two-dimensional metal-L<sup>O</sup> layer and a one-dimensional metal-tib chain and simplified into a 4-nodal (3,4,4,5)-connected net. <b>6</b> and <b>7</b> feature rare binodal (3,5)-connected {3.7<sup>2</sup>}­{3<sup>2</sup>.7<sup>5</sup>.8<sup>3</sup>} <b>fsf/polar</b> net and (3,5)-connected {6<sup>3</sup>}­{6<sup>9</sup>.8} <b>hms</b> net. Structural analyses show that each type of compound with the same metal components and <b>tib</b> ligands exhibit such interesting topological variations, which are derived from different orientations of three carboxylate ligands. Other properties of these compounds were also investigated, such as elemental and thermogravimetric analyses, photoluminescent spectroscopy, and magnetic behavior

    Structural Variation within Heterometallic Uranyl Hybrids Based on Flexible Alkyldiphosphonate Ligands

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    Five novel zinc uranyl diphosphonates have been hydrothermally synthesized by using a series of flexible diphosphonate ligands, including ethane-1,2-diyldiphosphonic acid (H<sub>4</sub>EDP), propane-1,3-diyldiphosphonic acid (H<sub>4</sub>PDP), and butane-1,4-diyldiphosphonic acid (H<sub>4</sub>BDP). Compound Zn­(H<sub>2</sub>tib)­(UO<sub>2</sub>)<sub>2</sub>(EDP)­(HEDP)­(H<sub>2</sub>EDP)<sub>0.5</sub>·3H<sub>2</sub>O (<b>EDP-ZnU1</b>, tib = 1,3,5-tri­(1H-imidazol-1-yl)­benzene) comprises dimeric U<sub>2</sub>O<sub>12</sub> unit condensed by two UO<sub>7</sub> pentagonal bipyramids, which are further connected by Zn-centered polyhedra and EDP ligands resulting in a 3-dimensional framework. Compound [Zn­(bipy)­(H<sub>2</sub>O)]­(UO<sub>2</sub>)­(PDP) (<b>PDP-ZnU1</b>, bipy = 2,2′-bipyridine) also features U<sub>2</sub>O<sub>12</sub> dimers and Zn-centered polyhedra, but a layered arrangement is formed. Different from that in <b>PDP-ZnU1</b>, the uranium exists in the form of UO<sub>6</sub> tetragonal bipyramid and is surrounded by four PDP ligands to generate the layered structure of Zn­(bipy)­(UO<sub>2</sub>)­(PDP) (<b>PDP-ZnU2</b>). ZnO<sub>2</sub>N<sub>2</sub> tetrahedra are connected on both sides of the layers. Both Zn<sub>2</sub>(phen)<sub>4</sub>(UO<sub>2</sub>)<sub>3</sub>(BDP)­(HBDP)<sub>2</sub>·4H<sub>2</sub>O (<b>BDP-ZnU1</b>, phen = 1,10-phenanthroline) and Zn<sub>2</sub>(bipy)<sub>2</sub>(UO<sub>2</sub>)<sub>3</sub>(HBDP)<sub>2</sub>(H<sub>2</sub>BDP)<sub>2</sub> (<b>BDP-ZnU2</b>) contain U<sub>2</sub>O<sub>12</sub> dimers and UO<sub>6</sub> tetragonal bipyramids. In <b>BDP-ZnU1</b>, uranyl centers are bridged by BDP to form a 2-dimensional structure, on which Zn­(phen)<sub>2</sub> are decorated. Whereas in <b>BDP-ZnU2</b>, uranyl phosphonate layers are connected by bridging ZnO<sub>3</sub>N<sub>2</sub> to produce framework structure. All of these compounds have been investigated by IR and photoluminescent spectroscopy. Their characteristic green light emissions have been attributed to transition properties of uranyl dications

    Rational Assembly of Co/Cd-MOFs Featuring Topological Variation

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    Three different carboxylate ligands of 4,4′-biphthalic acid (<b>H</b><sub><b>4</b></sub><b>L</b>, linear), 4,4′-axydiphthalic acid (<b>H</b><sub><b>4</b></sub><b>L</b><sup><b>O</b></sup>, V-shaped), and thiophene-2,5-dicarboxylic acid (<b>H</b><sub><b>2</b></sub><b>L</b><sup><b>S</b></sup>, V-shaped and heteroatomic ring) were selected as two-connected nodes to react with Co­(II) or Cd­(II) nitrates in the presence of 1,3,5-tris­(1-imidazolyl)­benzene (<b>tib</b>, Y-shaped and tridentate). Hydrothermal reactions in distilled water afforded seven new Co­(Cd)-MOFs, namely, M­(<b>tib</b>)­(H<sub>2</sub>L)­(H<sub>2</sub>O)<sub>2</sub>·H<sub>2</sub>O (M = Co, <b>1</b>; Cd, <b>2)</b>, M<sub>2</sub>(<b>tib</b>)<sub>2</sub>(H<sub>2</sub>L<sup>O</sup>)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub> (M = Co, <b>3</b>; Cd, <b>4</b>), Co<sub>2</sub>(<b>tib</b>)­(L<sup>O</sup>)·H<sub>2</sub>O (<b>5</b>), Co­(<b>tib</b>)­(L<sup>S</sup>)·2H<sub>2</sub>O (<b>6</b>), and Cd­(<b>tib</b>)­(L<sup>S</sup>)·3H<sub>2</sub>O (<b>7</b>). Of particular interest, they exhibit four interesting nets. <b>1</b>–<b>2</b> and <b>3</b>–<b>4</b> feature binodal (3,4) and (3,3,4,4)-connected nets if H-bonds are taken into account, respectively. <b>5</b> is composed of a two-dimensional metal-L<sup>O</sup> layer and a one-dimensional metal-tib chain and simplified into a 4-nodal (3,4,4,5)-connected net. <b>6</b> and <b>7</b> feature rare binodal (3,5)-connected {3.7<sup>2</sup>}­{3<sup>2</sup>.7<sup>5</sup>.8<sup>3</sup>} <b>fsf/polar</b> net and (3,5)-connected {6<sup>3</sup>}­{6<sup>9</sup>.8} <b>hms</b> net. Structural analyses show that each type of compound with the same metal components and <b>tib</b> ligands exhibit such interesting topological variations, which are derived from different orientations of three carboxylate ligands. Other properties of these compounds were also investigated, such as elemental and thermogravimetric analyses, photoluminescent spectroscopy, and magnetic behavior

    A Dual-Functional Luminescent MOF Sensor for Phenylmethanol Molecule and Tb<sup>3+</sup> Cation

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    A highly luminescent porous metal–organic framework Cd<sub>3</sub>(L)<sub>2.5</sub>(4-PTZ)­(DMF)<sub>3</sub>, labeled as <b>NBU-9</b>, has been designedly synthesized based on Cd­(NO<sub>3</sub>)<sub>2</sub>·4H<sub>2</sub>O and mixed ligands of 4-(1<i>H</i>-tetrazol-5-yl)­pyridine (4-HPTZ) with N-coordinated sites and thiophene-2,5-dicarboxylic acid (H<sub>2</sub>L) with heteroatomic (S) ring and carboxylate groups in <i>N</i>,<i>N</i>-dimethylformamide (DMF) at 100 °C for 3 days. The interesting result is that this compound <b>NBU-9</b> can be also obtained via the mixed raw materials of Cd­(NO<sub>3</sub>)<sub>2</sub>·4H<sub>2</sub>O, 4-cyanopyridine, NaN<sub>3</sub>, and H<sub>2</sub>L under solvothermal condition at a higher temperature of 140 °C for 3 days, involving <i>in situ</i> ligand synthesis of 4-HPTZ. Its structure was indentified by single-crystal X-ray study, powder X-ray diffraction, element analysis, and TGA results. Structural analysis shows that the three-dimensional framework of <b>NBU-9</b> contains cubic channels of 9.59 × 10.26 Å<sup>2</sup> covered by a large number of open S- and O-coordinated sites and can be simplified into a 8-connected uninodal <i>eca</i> net with high potential solvent accessible volumes of 34.1%. Its luminescent properties demonstrate that <b>NBU-9</b> as a multifunctional sensory material realizes the selective detection for the phenylmethanol molecule on the basis of fluorescence quenching mechanism and effectively sensitizing the visible emitting of the Tb<sup>3+</sup> cation based on luminescence enhancement

    Hierarchical Two-Dimensional Conductive Metal–Organic Framework/Layered Double Hydroxide Nanoarray for a High-Performance Supercapacitor

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    A novel hierarchical nanoarray material based on a two-dimensional metal–organic framework (Ni-CAT) and a layered double hydroxide (NiCo-LDH) was fabricated on a nickel foam substrate. By taking advantage of the regular nanostructure and making full use of the high porosity and excellent conductivity, the hybrid material exhibits a high areal capacitance for a supercapacitor (3200 mF cm<sup>–2</sup> at 1 mA cm<sup>–2</sup>)

    An Ultrastable Metal–Organic Framework with Open Coordinated Sites Realizing Selective Separation toward Cationic Dyes in Aqueous Solution

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    A novel Zn-based metal–organic framework (MOF) was synthesized from the mixed ligands, 3,3′,5,5′-azoxybenzenetetracarboxylic acid (H<sub>4</sub>AOBTC) and 1,4-bis­(1<i>H</i>-benzo­[d]­imidazol-1-yl)­benzene (phenDIB) ligand. The crystal structure of the complex exhibits an interpenetrated three-dimensional framework that can be simplified as a (4,4)-connected 2-nodal <i>bbf</i> net. This MOF displays extraordinary thermostability in boiling water for 12 h and chemical stability in a wide pH range of 2–13. The most intriguing feature is that it can successfully separate cationic dyes from mixed dye molecules in aqueous solution with high effectivity and selectivity, even for rhodamine B molecule with a large size. Furthermore, this material is reusable, and the adsorbed dye molecules can be released and recovered completely. It is very important for the practical application from a view of environmental protection and resource recycling
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