19 research outputs found

    One ligand capable of <i>in situ</i> reaction in a mixed-ligand system with two new different frameworks

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    <p>The <i>in situ</i> ligand 2,3-pyrazinedicarboxylic acid (2,3-H<sub>2</sub>pzdc) mixed with 1,1â€Č-(1,4-butanediyl)bis(benzimidazole) (bbbi) is used to form two coordination polymers ([Cd(2,3-pzdc)(bbbi)] (<b>1</b>) and [Cd<sub>2</sub>Cl<sub>3</sub>(2-pzc)(bbbi)<sub>2</sub>] (<b>2</b>)) under hydrothermal conditions. Complex <b>1</b> was obtained in the absence of <i>in situ</i> reaction and <b>2</b> was synthesized with 2,3-H<sub>2</sub>pzdc <i>in situ</i> generating 2-pyrazinecarboxylate (2-pzc<sup>−</sup>). The structural details reveal that <b>1</b> has a 3D framework with dia topology, and <b>2</b> is a 2D layer structure and develops a 3D supramolecular structure via strong Ï€â‹ŻÏ€ stacking interactions. The ligand effects were compared for the two frameworks. In addition, fluorescence properties and thermal stabilities of <b>1</b> and <b>2</b> in the solid were studied.</p

    Computational Design of Porous Organic Frameworks for High-Capacity Hydrogen Storage by Incorporating Lithium Tetrazolide Moieties

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    We propose to incorporate a lithium tetrazolide group into porous materials for enhancing hydrogen storage capacity. The lithium tetrazolide group is much more stable and polarized than the models made by doping aromatic groups with lithium atoms. More importantly, each of the lithium tetrazolide provides 14 binding sites for hydrogen molecules with modest interaction energies. The advantage of multiple binding sites with modest binding energies is partially demonstrated by constructing a new porous aromatics framework (PAF-4) with the lithium tetrazolide moieties and predicting its hydrogen uptake using first-principles GCMC simulations. The predicted hydrogen uptake reaches 4.9 wt % at 233 K and 10 MPa, which exceeds the 2010 DOE target of 4.5 wt %

    Fabrication of COF-MOF Composite Membranes and Their Highly Selective Separation of H<sub>2</sub>/CO<sub>2</sub>

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    The search for new types of membrane materials has been of continuous interest in both academia and industry, given their importance in a plethora of applications, particularly for energy-efficient separation technology. In this contribution, we demonstrate for the first time that a metal–organic framework (MOF) can be grown on the covalent-organic framework (COF) membrane to fabricate COF-MOF composite membranes. The resultant COF-MOF composite membranes demonstrate higher separation selectivity of H<sub>2</sub>/CO<sub>2</sub> gas mixtures than the individual COF and MOF membranes. A sound proof for the synergy between two porous materials is the fact that the COF-MOF composite membranes surpass the Robeson upper bound of polymer membranes for mixture separation of a H<sub>2</sub>/CO<sub>2</sub> gas pair and are among the best gas separation MOF membranes reported thus far

    Synthesis of an <i>S</i><sub>T</sub> = 7 [Mn<sub>3</sub>] Mixed-Valence Complex Based on 1,3-Propanediol Ligand Derivatives and Its One-Dimensional Assemblies

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    Controlled organization of high-spin complexes and single-molecule magnets is a great challenge in molecular magnetism in order to study the effect of the intercomplex magnetic interactions on the intrinsic properties of a given magnetic object. In this work, a new <i>S</i><sub>T</sub> = 7 trinuclear mixed-valence Mn complex, [Mn<sup>III</sup>Mn<sup>II</sup><sub>2</sub>(L<sub>A</sub>)<sub>2</sub>(Br)<sub>4</sub>(CH<sub>3</sub>OH)<sub>6</sub>] ·Br·(CH<sub>3</sub>OH)<sub>1.5</sub>·(H<sub>2</sub>O)<sub>0.5</sub> (<b>1</b>), is reported using a pyridinium-functionalized 1,3-propanediol ligand (H<sub>2</sub>L<sub>A</sub>Br = 1-(3-bromo-2,2-bis­(hydroxymethyl)­propyl)­pyridinium bromide). Using azido anions as bridging ligands and different pyridinium-functionalized 1,3-propanediol ligands (H<sub>2</sub>L<sub>B</sub>Br = 1-(3-bromo-2,2-bis­(hydroxymethyl)­propyl)-4-picolinium bromide; H<sub>2</sub>L<sub>C</sub>Br = 1-(3-bromo-2,2-bis­(hydroxymethyl)­propyl)-3,5-lutidinium bromide), the linear [Mn<sup>III</sup>Mn<sup>II</sup><sub>2</sub>L<sub>2</sub>X<sub>4</sub>]<sup>+</sup> building block has been assembled into one-dimensional coordination networks: [Mn<sup>III</sup>Mn<sup>II</sup><sub>2</sub>(L<sub>A</sub>)<sub>2</sub>(Br)<sub>4</sub>(CH<sub>3</sub>OH)<sub>4</sub>(N<sub>3</sub>)]·((C<sub>2</sub>H<sub>5</sub>)<sub>2</sub>O)<sub>1.25</sub> (<b>2∞</b>), [Mn<sup>III</sup>Mn<sup>II</sup><sub>2</sub>(L<sub>B</sub>)<sub>2</sub>(Br)<sub>4</sub>(C<sub>2</sub>H<sub>5</sub>OH)­(CH<sub>3</sub>OH)­(H<sub>2</sub>O)<sub>2</sub>(N<sub>3</sub>)]·(H<sub>2</sub>O)<sub>0.25</sub> (<b>3∞</b>), and [Mn<sup>III</sup>Mn<sup>II</sup><sub>2</sub>(L<sub>C</sub>)<sub>2</sub>(Cl)<sub>3.8</sub>(Br)<sub>0.2</sub>(C<sub>2</sub>H<sub>5</sub>OH)<sub>3</sub>(CH<sub>3</sub>OH)­(N<sub>3</sub>)] (<b>4∞</b>). The syntheses, characterization, crystal structures, and magnetic properties of these new [Mn<sub>3</sub>]-based materials are reported

    UiO-66-Coated Mesh Membrane with Underwater Superoleophobicity for High-Efficiency Oil–Water Separation

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    A UiO-66-coated mesh membrane with micro- and nanostructures was designed and successfully fabricated on steel mesh through a simple solution immersion process, exhibiting hydrophilic and underwater superoleophobic properties. It displays an outstanding oil–water separation efficiency over 99.99% with a high water permeation flux of 12.7 × 10<sup>4</sup> L m<sup>–2</sup> h<sup>–1</sup>, so high purity water (with the residual oil content less than 4 ppm) can be readily obtained from such a simple mesh membrane from various oil–water mixtures. Its large-scale membrane production will facilitate its practical usage for the industrial and environmental water purification

    Three-Dimensional Covalent Organic Frameworks with Dual Linkages for Bifunctional Cascade Catalysis

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    Covalent organic frameworks (COFs) are an emerging class of porous crystalline polymers with broad potential applications. So far, the availability of three-dimensional (3D) COFs is limited and more importantly only one type of covalent bond has been successful used for 3D COF materials. Here, we report a new synthetic strategy based on dual linkages that leads to 3D COFs. The obtained 3D COFs show high specific surface areas and large gas uptake capacities, which makes them the top COF material for gas uptake. Furthermore, we demonstrate that the new 3D COFs comprise both acidic and basic sites, and act as excellent bifunctional catalysts for one-pot cascade reactions. The new synthetic strategy provides not only a general and versatile approach to synthesize 3D COFs with sophisticated structures but also expands the potential applications of this promising class of porous materials

    UiO-66-Coated Mesh Membrane with Underwater Superoleophobicity for High-Efficiency Oil–Water Separation

    No full text
    A UiO-66-coated mesh membrane with micro- and nanostructures was designed and successfully fabricated on steel mesh through a simple solution immersion process, exhibiting hydrophilic and underwater superoleophobic properties. It displays an outstanding oil–water separation efficiency over 99.99% with a high water permeation flux of 12.7 × 10<sup>4</sup> L m<sup>–2</sup> h<sup>–1</sup>, so high purity water (with the residual oil content less than 4 ppm) can be readily obtained from such a simple mesh membrane from various oil–water mixtures. Its large-scale membrane production will facilitate its practical usage for the industrial and environmental water purification

    Fast, Ambient Temperature and Pressure Ionothermal Synthesis of Three-Dimensional Covalent Organic Frameworks

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    Covalent organic frameworks (COFs) are an emerging class of porous crystalline polymers with wide range of potential applications. However, the availability of three-dimensional (3D) COFs is still limited, and their synthesis is confined to the high-temperature solvothermal method. Here, we report for the first time a general and simple strategy to produce a series of 3D ionic liquid (IL)-containing COFs (3D-IL-COFs) by using IL as a green solvent. The syntheses are carried out at ambient temperature and pressure accompanied by a high reaction speed (e.g., only three mins for 3D-IL-COF-1), and the IL can be reused without activity loss. Furthermore, the 3D-IL-COFs show impressive performance in the separation of CO<sub>2</sub>/N<sub>2</sub> and CO<sub>2</sub>/CH<sub>4</sub>. This research thus presents a potential pathway to green large-scale industrial production of COFs

    UiO-66-Coated Mesh Membrane with Underwater Superoleophobicity for High-Efficiency Oil–Water Separation

    No full text
    A UiO-66-coated mesh membrane with micro- and nanostructures was designed and successfully fabricated on steel mesh through a simple solution immersion process, exhibiting hydrophilic and underwater superoleophobic properties. It displays an outstanding oil–water separation efficiency over 99.99% with a high water permeation flux of 12.7 × 10<sup>4</sup> L m<sup>–2</sup> h<sup>–1</sup>, so high purity water (with the residual oil content less than 4 ppm) can be readily obtained from such a simple mesh membrane from various oil–water mixtures. Its large-scale membrane production will facilitate its practical usage for the industrial and environmental water purification

    UiO-66-Coated Mesh Membrane with Underwater Superoleophobicity for High-Efficiency Oil–Water Separation

    No full text
    A UiO-66-coated mesh membrane with micro- and nanostructures was designed and successfully fabricated on steel mesh through a simple solution immersion process, exhibiting hydrophilic and underwater superoleophobic properties. It displays an outstanding oil–water separation efficiency over 99.99% with a high water permeation flux of 12.7 × 10<sup>4</sup> L m<sup>–2</sup> h<sup>–1</sup>, so high purity water (with the residual oil content less than 4 ppm) can be readily obtained from such a simple mesh membrane from various oil–water mixtures. Its large-scale membrane production will facilitate its practical usage for the industrial and environmental water purification
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