| 1. |
- Amombo Noa, Francoise Mystere, 1988, et al.
(författare)
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Metal-Organic Frameworks with Hexakis(4-carboxyphenyl)benzene: Extensions to Reticular Chemistry and Introducing Foldable Nets
- 2020
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 142:20, s. 9471-9481
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Tidskriftsartikel (refereegranskat)abstract
- Nine metal-organic frameworks have been prepared with the hexagon-shaped linker 1,2,3,4,5,6-hexakis(4-carboxyphenyl)-benzene (H(6)cpb) by solvothermal reactions in dimethylformamide (dmf) or dimethylacetamide (dmac) with acetic acid or formic acid as modulators: [Bi-2(cpb)(acetato)(2)(dmf)(2)]center dot 2dmf CTH-6 forms a rtl-net; 2(H2NMe2)[Cu-2(cpb)] CTH-7 forms a kgd-net; [Fe-4(cpb)-(acetato)(2)(dmf)(4)] CTH-8 and [Co-4(cpb)(acetato)(2)(dmf)(4)] CTH-9 are isostructural and form yav-nets; 2(HNEt3)[Fe-2(cpb)] CTH-10 and the two polymorphs of 2(H2NMe2)[Zn-2(cpb)]center dot 1.5dmac, Zn-MOF-888 and CTH-11, show kgd-nets; [Cu-2(cpb)-(acetato)(2)(dmf)(2)]center dot 2dmf, CTH-12, forms a mixed coordination and hydrogen-bonded sql-net; and 2(H2NMe2)[Zn-2(cpb)] CTH-13, a similarly mixed yav-net. Surface area values (Brunauer-Emmett-Teller, BET) range from 34 m(2) g(-1) for CTH-12 to 303 m(2) g(-1) for CTH-9 for samples activated at 120 degrees C in dynamic vacuum. All compounds show normal (10-fold higher) molar CO2 versus N-2 uptake at 298 K, except the 19-fold CO2 uptake for CTH-12 containing Cu(II) dinuclear paddle-wheels. We also show how perfect hexagons and triangles can combine to a new 3D topology laf, a model of which gave us the idea of foldable network topologies, as the laf-net can fold into a 2D form while retaining the local geometry around each vertex. Other foldable nets identified are cds, cds-a, ths, sqc163, clh, jem, and tfc covering the basic polygons and their combinations. The impact of this concept on "breathing" MOFs is discussed. I-2 sorption, both from gas phase and from MeOH solution, into CTH-7 were studied by time of flight secondary ion mass spectrometry (ToF-SIMS) on dried crystals. I-2 was shown to have penetrated the crystals, as layers were consecutively peeled off by the ion beam. We suggest ToF-SIMS to be a method for studying sorption depth profiles of MOFs.
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| 2. |
- Benecke, Jannik, et al.
(författare)
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Observation of three different linker conformers in a scandium ferrocenedicarboxylate coordination polymer
- 2020
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033 .- 1466-8033. ; 22:34, s. 5569-5572
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Tidskriftsartikel (refereegranskat)abstract
- Electron and powder diffraction were combined to elucidate the structure of the new coordination polymer [Sc-2(FcDC)(3)] based on 1,1'-ferrocenedicarboxylate (FcDC(2-)), denoted as CAU-50. Remarkably, three different conformers of the very same linker molecule are observed, two of which serve as connectors for the scandium cations while one conformer acts as capping agent.
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| 3. |
- Benecke, Jannik, et al.
(författare)
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Polymorphous Indium Metal-Organic Frameworks Based on a Ferrocene Linker : Redox Activity, Porosity, and Structural Diversity
- 2020
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 59:14, s. 9969-9978
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Tidskriftsartikel (refereegranskat)abstract
- The metallocene-based linker molecule 1,1'-ferrocenedicarboxylic acid (H(2)FcDC) was used to synthesize four different polymorphs of composition [In(OH)(FeC12H8O4)]. Using conventional solvent-based synthesis methods and varying the synthetic parameters such as metal source, reaction temperature, and solvent, two different MOFs and one ID-coordination polymer denoted as CAU-43 (1), In-MIL-53-FcDC_a (2), and InFcDC (3) were obtained. Furthermore, thermal treatment of CAU-43 (1) at 190 degrees C under vacuum yielded a new polymorph of 2, In-MIL-53-FcDC_b (4). Both MOFs 2 and 4 crystallize in a MIL-53 type structure, but in different space groups C2/m for 2 and P (1) over bar for 4. The structures of the four title compounds were determined by single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), or a combination of three-dimensional electron diffraction measurements (3D ED) and PXRD. N-2 sorption experiments of 1, 2, and 4 showed specific surface areas of 355 m(2) g(-)(1), 110 m(2) g(-1), and 140 m(2) g(-)(1), respectively. Furthermore, the electronic properties of the title compounds were characterized via Mossbauer and EPR spectroscopy. All Mossbauer spectra showed the characteristic doublet, proving the persistence of the ferrocene moiety. In the cases of 1, 3, and 4, appreciable impurities of ferrocenium ions could be detected by electron paramagnetic resonance spectroscopy. Cyclovoltammetric experiments were performed to demonstrate the accessible redox activity of the linker molecule of the title compounds. A redox process of FcDC(2-) with oxidation (between 0.86 and 0.97 V) and reduction wave (between 0.69 and 0.80 V) was observed.
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| 4. |
- Cui, Peng, et al.
(författare)
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An Expandable Hydrogen-Bonded Organic Framework Characterized by Three-Dimensional Electron Diffraction
- 2020
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 142:29, s. 12743-12750
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Tidskriftsartikel (refereegranskat)abstract
- A molecular crystal of a 2-D hydrogen-bonded organic framework (HOF) undergoes an unusual structural transformation after solvent removal from the crystal pores during activation. The conformationally flexible host molecule, ABTPA, adapts its molecular conformation during activation to initiate a framework expansion. The microcrystalline activated phase was characterized by three-dimensional electron diffraction (3D ED), which revealed that ABTPA uses out-of-plane anthracene units as adaptive structural anchors. These units change orientation to generate an expanded, lower density framework material in the activated structure. The porous HOF, ABTPA-2, has robust dynamic porosity (SA(BET) = 1 183 m(2) g(-1)) and exhibits negative area thermal expansion. We use crystal structure prediction (CSP) to understand the underlying energetics behind the structural transformation and discuss the challenges facing CSP for such flexible molecules.
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| 5. |
- Frank, Sara, et al.
(författare)
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Exploring the influence of atomic level structure, porosity, and stability of bismuth(iii) coordination polymers on electrocatalytic CO2 reduction
- 2021
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 9:46, s. 26298-26310
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Tidskriftsartikel (refereegranskat)abstract
- Bismuth-based coordination polymers (CPs) have recently attracted attention as catalyst precursors for the electrocatalytic CO2 reduction reaction (eCO(2)RR). We present a comparative study by investigating six bismuth-based compounds in-depth to elucidate the correlation between their structures and their catalytic CO2-to-formate conversion. Thereby, we identify structural indicators of the pristine CPs resulting in optimized catalytic performance, paving the way for future design of CP derived catalysts. The structural properties of the six pristine materials vary in terms of porosity (from non-porous to 495 m(2) g(-1)), linker type (carboxylate- or phenolate-based), thermal- and chemical stability, and metal content. Herein, electrochemical studies are combined with comprehensive structural investigations using electron microscopy, powder X-ray diffraction, and X-ray absorption spectroscopy. Our study reveals that low chemical stability of the pristine CPs is crucial for the conversion of the precursors into active Bi2O2CO3 and of paramount importance for the eCO(2)RR activity, while the nature of the pristine material mostly influence the catalyst morphology and transport properties. Of the six investigated CPs, the best performing compounds selectively convert CO2 to formate with faradaic efficiencies in the range 80(3)-95(3)% and current densities of 5(1)-8(1) mA cm(-2) at -0.97 V-RHE.
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| 6. |
- Huang, Zhehao, et al.
(författare)
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3D electron diffraction as an important technique for structure elucidation of metal-organic frameworks and covalent organic frameworks
- 2021
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Ingår i: Coordination chemistry reviews. - : Elsevier BV. - 0010-8545 .- 1873-3840. ; 427
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Forskningsöversikt (refereegranskat)abstract
- Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have emerged as the most widely investigated classes of porous materials during the past two decades. The almost unlimited combination of building units (metal clusters and organic molecules) endows highly tuneable porosities and functionalities that are appealing for a wide scope of applications. The applications of MOFs and COFs depend on their physical and chemical properties, which in turn are determined by the arrangement of atoms - the crystal structures. Therefore, structure determination is arguably the most important characterization step for MOFs and COFs. While single crystal X-ray diffraction (SCXRD) is the most widely used method for structure determination, many MOFs and COFs are synthesized in too small sizes or their crystal qualities are too low for SCXRD. During recent years, three-dimensional electron diffraction (3DED) methods has undergone rapid developments and can be used for structure determination of nano- and submicro-sized crystals to overcome this fundamental drawback. In this review, we summarize the development of 3DED methods and their applications for structure elucidation of MOFs and COFs. Advances of 3DED data collection techniques are described, from step-wise rotation to continuous rotation of the crystal. The latter allows fast data collection which is crucial for beam sensitive materials including MOFs and COFs. Examples of ab initio structure determination of various MOFs and COFs by using 3DED are presented, with highlighted examples for solving the structures of mesoporous MOFs, mixed-metal MOFs, flexible MOFs, and for studying host-guest interactions. Finally, the accuracy and reproducibility of structure determination by 3DED are presented. We show the structure information obtained from 3DED provides crucial insights into structure-property relationships, which could further accelerate the development of new functional materials.
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| 7. |
- Li, Man-Bo, et al.
(författare)
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Silver-Triggered Activity of a Heterogeneous Palladium Catalyst in Oxidative Carbonylation Reactions
- 2020
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 59:26, s. 10391-10395
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Tidskriftsartikel (refereegranskat)abstract
- A silver-triggered heterogeneous Pd-catalyzed oxidative carbonylation has been developed. This heterogeneous process exhibits high efficiency and good recyclability, and was utilized for the one-pot construction of polycyclic compounds with multiple chiral centers. AgOTf was used to remove chloride ions in the heterogeneous catalyst Pd-AmP-CNC, thereby generating highly active Pd-II, which results in high efficiency of the heterogeneous catalytic system.
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| 8. |
- Piątek, Jędrzej, et al.
(författare)
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Toward Sustainable Li-Ion Battery Recycling : Green Metal-Organic Framework as a Molecular Sieve for the Selective Separation of Cobalt and Nickel
- 2021
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 9:29, s. 9770-9778
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Tidskriftsartikel (refereegranskat)abstract
- The growing demand for Li-ion batteries (LIBs) has made their postconsumer recycling an imperative need toward the recovery of valuable metals, such as cobalt and nickel. Nevertheless, their recovery and separation from active cathode materials in LIBs, via an efficient and environmentally friendly process, have remained a challenge. In this work, we approach a simple and green method for the selective separation of nickel ions from mixed cobalt-nickel aqueous solutions under mild conditions. We discovered that the bioinspired microporous metal-organic framework (MOF) SU-101 is a selective sorbent toward Ni2+ ions at pH 5-7 but does not adsorb Co2+ ions. According to the Freundlich isotherm, the adsorption capacity toward Ni2+ reached 100.9 mg.g(-1), while a near-zero adsorption capacity was found for Co2+ ions. Ni2+ removal from aqueous solutions was performed under mild conditions (22 degrees C and pH 5), with a high yield up to 96%. The presence of Ni2+ ions adsorbed on the surface of the material has been proven by solid-state H-1 nuclear magnetic resonance spectroscopy. Finally, the separation of Ni2+ from Co2+ from binary solutions was obtained with approximately 30% yield for Ni2+, with a near-zero adsorption of Co2+, which has been demonstrated by UV-vis spectroscopy. The ion adsorption process of Ni2+ and Co2+ ions was additionally studied by means of classical molecular dynamics calculations (force fields), which showed that the Ni2+ ions were more prone to enter the MOF canals by replacing some of their coordinated water molecules. These results offer a green pathway toward the recycling and separation of valuable metals from cobalt-containing LIBs while providing a sustainable route for waste valorization in a circular economy.
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| 9. |
- Posevins, Daniels, et al.
(författare)
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Highly Diastereoselective Palladium-Catalyzed Oxidative Cascade Carbonylative Carbocyclization of Enallenols
- 2020
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Ingår i: Organic Letters. - : American Chemical Society (ACS). - 1523-7060 .- 1523-7052. ; 22:2, s. 417-421
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Tidskriftsartikel (refereegranskat)abstract
- A palladium-catalyzed oxidative cascade carbonylative carbocyclization of enallenols was developed. Under mild reaction conditions, a range of cis-fused [5,5] bicyclic gamma-lactones and gamma-lactams with a 1,3-diene motif were obtained in good yields with high diastereoselectivity. The obtained lactone/lactam products are viable substrates for a stereoselective Diels-Alder reaction with N-phenylmaleimide, providing polycyclic compounds with increased molecular complexity.
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| 10. |
- Rabe, Timo, et al.
(författare)
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Influence of the substitution pattern of four naphthalenedicarboxylic acids on the structures and properties of group 13 metal-organic frameworks and coordination polymers
- 2020
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 49:15, s. 4861-4868
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Tidskriftsartikel (refereegranskat)abstract
- Metal-organic frameworks containing Ga3+ ions and four differently substituted naphthalenedicarboxylates (ndc(2-)) have been synthesized and characterized. The Ga3+ ions are six-fold coordinated by oxygen atoms in all title compounds, but two different inorganic building units, i.e. trans corner-sharing and cis,trans edge-sharing octahedra are observed. Crystal structures were validated by Rietveld refinements against powder X-ray diffraction data. [Ga(OH)(1,4-ndc)]2H(2)O crystallizes in a non-breathing MIL-53 type structure with two different pore sizes (5.5 x 5.5 angstrom and 9 x 9 angstrom). It is non-porous with respect to nitrogen but has a water adsorption capacity of about 155 mg g(-1) and a thermal stability of up to 240 degrees C. The dense compound [Ga(OH)(1,8-ndc)] crystallizes in a new layered structure motif, which is related to the crystal structure of MIL-122 ([Al(OH)((O2C)(4)C6H2)]). The third and fourth compounds [Ga-2(OH)(4)(2,3-ndc)]H2O and [Ga(OH)(2,6-ndc)]H2O are isoreticular to CAU-15 ([Al-2(OH)(4)(2,3-bdc)]H2O) and MIL-69 ([Al(OH)(2,6-ndc)]H2O), respectively. The last two compounds are non-porous toward nitrogen but reversible dehydration was demonstrated. For comparison, the two new compounds [Al(OH)(1,8-ndc)] and [Al-2(OH)(4)(2,3-ndc)]H2O, which are isostructural to the newly described gallium compounds, were also synthesized and fully characterized. The Al-containing coordination polymers exhibit higher temperature stabilities compared to their isostructural Ga compounds.
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