| 1. |
- Achenbach, Bastian, et al.
(författare)
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Porous Salts Containing Cationic Al24-Hydroxide-Acetate Clusters from Scalable, Green and Aqueous Synthesis Routes
- 2023
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Ingår i: Angewandte Chemie International Edition. - 1433-7851 .- 1521-3773. ; 62:29
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Tidskriftsartikel (refereegranskat)abstract
- The solution chemistry of aluminum is highly complex and various polyoxocations are known. Here we report on the facile synthesis of a cationic Al24 cluster that forms porous salts of composition [Al24(OH)56(CH3COO)12]X4, denoted CAU-55-X, with X=Cl−, Br−, I−, HSO4−. Three-dimensional electron diffraction was employed to determine the crystal structures. Various robust and mild synthesis routes for the chloride salt [Al24(OH)56(CH3COO)12]Cl4 in water were established resulting in high yields (>95 %, 215 g per batch) within minutes. Specific surface areas and H2O capacities with maximum values of up to 930 m2 g−1 and 430 mg g−1 are observed. The particle size of CAU-55-X can be tuned between 140 nm and 1250 nm, permitting its synthesis as stable dispersions or as highly crystalline powders. The positive surface charge of the particles, allow fast and effective adsorption of anionic dye molecules and adsorption of poly- and perfluoroalkyl substances (PFAS).
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| 2. |
- Albat, Martin, et al.
(författare)
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Synthesis and crystal structure of three new bismuth(III) arylsulfonatocarboxylates
- 2017
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Ingår i: Zeitschrift für Kristallographie - Crystalline Materials. - : Walter de Gruyter GmbH. - 2194-4946 .- 2196-7105. ; 232:1-3, s. 245-253
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Tidskriftsartikel (refereegranskat)abstract
- Three new bismuth arylsulfonatocarboxylates [Bi(OH)(SB)] (1), [Bi-4(ST)(2)(HST)O-2(H2O)(2)]center dot H2O (2) and [Bi-4(ST)(2)O-3(H2O)(2)] (3) were synthesized under solvothermal reaction conditions at 180 degrees C using the potassium or sodium salt of 4-sulfobenzoic acid (H2SB) and 2-sulfoterephthalic acid (H3ST), respectively. The compounds were characterized in detail and the crystal structures were determined from single crystal X-ray diffraction data. Phase purity was confirmed by powder X-ray diffraction and elemental analysis. Structural comparisons to the only three other known bismuth sulfonatocarboxylates are presented. Due to the higher reaction temperatures employed for the synthesis of the title compounds a higher degree of condensation of the BiOx polyhedra (X = 7 or 8) to tetrameric units, 1D chains or a 2D layer is observed. Connection through the organic linker molecules leads to the formation of 3D coordination polymers in all three title compounds.
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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. |
- Gosch, Jonas, et al.
(författare)
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Discovery and In Situ Crystallization Studies of Cerium-Based Metal–Organic Frameworks with V-Shaped Linker Molecules
- 2023
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Ingår i: Inorganic Chemistry. - 0020-1669 .- 1520-510X. ; 62:51, s. 20929-20939
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery and characterization of two porous Ce(III)-based metal–organic frameworks (MOFs) with the V-shaped linker molecules 4,4′-sulfonyldibenzoate (SDB2–) and 4,4′-(hexafluoroisopropylidene)bis(benzoate) (hfipbb2–). The compounds of framework composition [Ce2(H2O)(SDB)3] (1) and [Ce2(hfipbb)3] (2) were obtained by using a synthetic approach in acetonitrile that we recently established. Structure determination of 1 was accomplished from 3D electron diffraction (3D ED) data, while 2 could be refined against powder X-ray diffraction (PXRD) data using the crystal structure of an isostructural La-MOF as the starting model. Their framework structures consist of chain-like inorganic building units (IBUs) or hybrid-BUs that are interconnected by the V-shaped linker molecules to form framework structures with channel-type pores. The composition of both compounds was confirmed by PXRD, elemental analysis, as well as NMR and IR spectroscopy. Interestingly, despite the use of (NH4)2[CeIV(NO3)6] in the synthesis, cerium ions in both MOFs occur exclusively in the + III oxidation state as determined by X-ray absorption near edge structure (XANES) and X-ray photoelectron spectroscopy (XPS). Thermal analyses reveal remarkably high thermal stabilities of ≥400 °C for the MOFs. Initial N2 sorption measurements revealed the peculiar sorption behavior of 2 which prompted a deeper investigation by Ar and CO2 sorption experiments. The combination with nonlocal density functional theory (NL-DFT) calculations adds to the understanding of the nature of the different pore diameters in 2. An extensive quasi-simultaneous in situ XANES/XRD investigation was carried out to unveil the formation of Ce-MOFs during the solvothermal syntheses in acetonitrile. The crystallization of the two Ce(III)-MOFs presented herein as well as two previously reported Ce(IV)-MOFs, all obtained by a similar synthetic approach, were studied. While the XRD patterns show time-dependent MOF crystallization, the XANES data reveal the presence of Ce(III) intermediates and their subsequent conversion to the MOFs. The addition of acetic acid in combination with the V-shaped linker molecule was identified as the crucial factor for the formation of the crystalline Ce(III/IV)-MOFs.
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| 5. |
- Gosch, Jonas, et al.
(författare)
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Solubility and Stability of Hexanuclear Ce(IV)-O Clusters
- 2023
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Ingår i: Chemistry of Materials. - 0897-4756 .- 1520-5002. ; 35:15, s. 5876-5885
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Tidskriftsartikel (refereegranskat)abstract
- Stable molecular clusters are of interest for targeted deposition in porous materials. In this work, we report the discovery of two new molecular Ce–O clusters of composition [Ce6O4(OH)4(NO3)4(DMF)4(C7H4O2X)8]·(DMF)4(H2O)2 (1-X) and [Ce6O4(OH)4(H2O)6(NO3)6(C7H4O2X)6] (2-X) (X = −Cl, −CHO, and −Br). Both cluster types contain a similar hexanuclear building unit, and crystal structures were determined from single-crystal X-ray diffraction or 3D electron diffraction data and subsequent Rietveld refinements against powder X-ray diffraction (PXRD) data. The crystal structure data is complemented by results from the local structure around the cerium ions, determined by extended X-ray absorption fine structure (EXAFS) measurements in the solid state. The composition of all Ce–O clusters was confirmed by elemental analysis, NMR and IR spectroscopy. The Ce–O clusters are highly soluble, up to 101 and 136 g/L for 1-Cl and 2-Cl, respectively, in organic solvents, which strongly depends on the type of cluster and functionalization of the benzoate ligands. Moreover, the structural and compositional integrity of dissolved clusters in different solvents was established. Recrystallization of 1-Cl from dichloromethane (DCM) and Raman spectroscopy confirm the integrity of both cluster types in solution. Further examination by EXAFS measurements on the Ce K-edge of clusters containing 4-chlorobenzoate reveals that only minor changes in the cerium environment of 1-Cl are observed upon dissolution in THF, DCM, and dioxane, while the results for 2-Cl indicate a partial degradation upon dissolution. After proving the stability, a cluster solution of 1-Cl was used to impregnate the mesoporous metal–organic framework Cr-MIL-101. Extensive characterization by PXRD, inductively coupled plasma-optical emission spectroscopy, and energy-dispersive X-ray spectroscopy, as well as thermogravimetry and N2-sorption measurements, confirm the successful insertion of Ce–O clusters into the large mesoporous cages of the framework. Due to the combination of high surface area and potential catalytic activity, the Cluster@MOF materials could be of high interest for application in heterogeneous catalysis.
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| 6. |
- Gosch, Jonas, et al.
(författare)
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Synthesis, Crystal Structure, and Photocatalytic Properties of Two Isoreticular Ce(IV)-MOFs with an Infinite Rod-Shaped Inorganic Building Unit
- 2023
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 62:13, s. 5176-5185
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Tidskriftsartikel (refereegranskat)abstract
- The use of the V-shaped linker molecules 4,4′-oxydibenzoic acid (H2ODB) and 4,4′-carbonyldibenzoic acid (H2CDB) led to the discovery of two isoreticular Ce(IV)-based metal–organic frameworks (MOFs) of composition [CeO(H2O)(L)], L = ODB2–, CDB2–, denoted CAU-58 (CAU = Christian-Albrechts-University). The recently developed Ce-MOF synthesis approach in acetonitrile as the solvent proved effective in accessing Ce(IV)-MOF structures with infinite rod-shaped inorganic building units (IBUs) and circumventing the formation of the predominantly observed hexanuclear [Ce6O8] cluster. For the structure determination of the isoreticular MOFs, three-dimensional electron diffraction (3D ED) and powder X-ray diffraction (PXRD) data were used in combination with density functional theory (DFT) calculations. [CeO(H2O)(CDB)] shows reversible H2O adsorption by stirring in water and thermal treatment at 190 °C, which leads to a unit cell volume change of 11%. The MOFs feature high thermal stabilities (T > 290 °C), which exceed those of most Ce(IV)-MOFs and can be attributed to the infinite rod-shaped IBU. Surface and bulk oxidation states of the cerium ions were analyzed via X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES). While Ce(III) ions are observed by the highly surface-sensitive XPS method, the bulk material contains predominantly Ce(IV) ions according to XANES. Application of the MOFs as catalysts for the catalytic degradation of methyl orange in aqueous solutions was also studied. While degradation activity for both MOFs was observed, only CAU-58-ODB revealed enhanced photocatalytic activity under ultraviolet (UV) light. The photocatalytic mechanism likely involves a ligand-to-metal charge transfer (LMCT) from the linkers to the Ce(IV) centers. Analyses by XANES and inductively coupled plasma-optical emission spectroscopy (ICP-OES) demonstrate that leaching of Cerium ions as well as partial reduction of Ce(IV) to Ce(III) takes place during catalysis. At the same time, PXRD data confirm the structural stability of the remaining MOF catalysts.
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| 7. |
- Halis, Seida, et al.
(författare)
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Dihydroxybenzoquinone as Linker for the Synthesis of Permanently Porous Aluminum Metal-Organic Frameworks
- 2016
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 55:15, s. 7425-7431
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Tidskriftsartikel (refereegranskat)abstract
- Two new dihydroxybenzoquinone-based metal-organic frameworks, ((CH3)(2)NH2)(3)[Al-4(L1)(3)(L1(center dot))(3)]center dot 3DMF (1, denoted CAU - 20) and ((CH3)(2)NH2)(3)[Al-4(L2)(3)(L2 center dot)(3)]center dot 9DMF (2, denoted CAU-20-Cl-2), were synthesized at 120 degrees C in PAU using 2,5-dihydroxy-p-benzoquinone ((C6H2(OH)(2)(O)(2)), H(2)L1) and 2,5-dichloro-3,6-dihydroxy-p-benzoquinone ((C6Cl2(OH)(2)(O)(2)), H(2)L2), respectively. Compared to other Al-MOFs, which contain carboxylate or phosphonate groups that connect the metal sites, in 1 and 2 the Al3+ are coordinated by oxido groups. The metal ions are octahedrally surrounded by oxygen atoms Of the deprotonated linker molecules to generate honeycomb layers with a metal to linker ratio of Al: L1/L2 = 2:3. The layers contain L1(2-) and L2(2-) ions as well as linker radical ions L1(center dot 3-) and L2(center dot 3-) in a molar ratio of 1 to 1. The presence of radical ions was confirmed by EPR and UV-vis-spectroscopic Measurements, and the composition was determined from a combination of PXRD, H-1, NMR, TG, and elemental analyses. Charge balance is accomplished through intercalation of (CH3)(2)NH2+ ions which are formed by partial hydrolysis of DMF. In the structures of 1 and 2 the eclipsed layers are AA and ABAB stacked, respectively, and one-dimensional hexagonal channels with diameters of ca. 9 and 6 angstrom are formed. Both compounds exhibit permanent porosity and have specific surface areas of 1440 and 1430 m(2) g(-1), respectively.
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| 8. |
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| 9. |
- Inge, A. Ken, et al.
(författare)
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Unprecedented Topological Complexity in a Metal-Organic Framework Constructed from Simple Building Units
- 2016
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 138:6, s. 1970-1976
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Tidskriftsartikel (refereegranskat)abstract
- A bismuth-based metal-organic framework (MOP), [Bi(BTC)(H2O)]center dot 2H(2)O center dot MeOH denoted CAU-17, was synthesized and found to have an exceptionally complicated structure with helical Bi-O rods cross-linked by 1,3,5-benzenetricarboxylate (BTC3-) ligands. Five crystallographically independent 1D channels including two hexagonal channels, two rectangular channels, and one triangular channel have accessible diameters of 9.6, 9.6, 3.6, 3.6, and 3.4 angstrom, respectively. The structure is further complicated by twinning. Rod-incorporated MOF structures typically have underlying nets with only one unique node and three or four unique edges. In contrast, topological analysis of CAU-17 revealed unprecedented complexity for a MOF structure with 54 unique nodes and 135 edges. The complexity originates from the rod packing and the rods themselves, which are related to aperiodic helices.
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| 10. |
- Koeppen, Milan, et al.
(författare)
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Solvent-Dependent Formation of Three New Bi-Metal-Organic Frameworks Using a Tetracarboxylic Acid
- 2018
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 18:7, s. 4060-4067
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Tidskriftsartikel (refereegranskat)abstract
- Systematic solvent screening using high-throughput solvothermal syntheses with bismuth nitrate pentahydrate and 1,2,4,5-tetrakis-(4-carboxyphenyl)benzene (H4TCPB) led to three new porous Bi-metal-organic frameworks [Bi-2(H2TCPB)(TCPB)(H2O)(2)]center dot xH(2)O (CAU-31), (NH2(CH3)(2) [Bi(TCPB)(H2O)]center dot xH(2)O (CAU-32), and [Bi-4(O)(2)(OH)(2)(H2TCPB)(TCPB)(H2O)(2)]center dot xH(2)O (CAU-33). Compounds CAU-31, -32, and -33 were synthesized in CH3OH, CH3OH/DMF, and DMF/toluene, respectively. The crystal structures were determined using electron diffraction and single-crystal X-ray diffraction in combination with the Rietveld method. The structures of CAU-31 and CAU-32 are composed of isolated Bi3+ ions as the inorganic building unit (IBU), which are connected by the linker ions to form a layered structure with inclined interpenetration and a three-dimensional anionic network, respectively. The IBU of CAU-33 consists of infinite bismuth-oxo rods forming a three-dimensional network by connection of the organic linkers. For CAU-33 structural flexibility was observed, and two phases denoted alpha- and beta-CAU-33 could be isolated.
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