| 1. |
- Bonneau, Charlotte, et al.
(author)
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Deconstruction of Crystalline Networks into Underlying Nets: Relevance for Terminology Guidelines and Crystallographic Databases
- 2018
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In: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7505 .- 1528-7483. ; 18:6, s. 3411-3418
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Journal article (peer-reviewed)abstract
- This communication briefly reviews why network topology is an important tool (for understanding, comparing, communicating, designing, and solving crystal structures from powder diffraction data) and then discusses the terms of an IUPAC project dealing with various aspects of network topology. One is the ambiguity in node assignment, and this question is addressed in more detail. First, we define the most important approaches: the "all node" deconstruction considering all branch points of the linkers, the "single node" deconstruction considering only components mixed, and the ToposPro "standard representation" also considering linkers as one node but, if present, takes each metal atom as a separate node. These methods are applied to a number of metal-organic framework structures (MOFs, although this is just one example of materials this method is applicable on), and it is concluded that the "all node" method potentially yields more information on the structure in question but cannot be recommended as the only way of reporting the network topology. In addition, several terms needing definitions are discussed.
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| 2. |
- Bonneau, Charlotte, et al.
(author)
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Open-Framework Germanate Built from the Hexagonal Packing of Rigid Cylinders
- 2009
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In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 48:21, s. 9962-9964
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Journal article (peer-reviewed)abstract
- We present a novel open-framework oxide material constructed from Ge10(O,OH)28 (Ge10) oxide clusters prepared via a nonsurfactant route. The material shows two distinct pore windows of 9.43 and 4.65 Å and a low framework density structure of 12.7 Ge atoms per 1000 Å3. The topological study leads to the recognition of a newly observed trinodal 6,7-heterocoordinated net related to the 7-coordinated swh net. The structure displays large rigid cylinders showing features indicating a growth mechanism by hard-sphere packing of the inorganic moiety similar to that observed in mesoporous materials.
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| 3. |
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| 4. |
- Boström, Hanna L. B., et al.
(author)
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How Reproducible is the Synthesis of Zr-Porphyrin Metal-Organic Frameworks? An Interlaboratory Study
- 2024
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In: Advanced Materials. - 0935-9648 .- 1521-4095. ; 36:15
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Journal article (peer-reviewed)abstract
- Metal-organic frameworks (MOFs) are a rapidly growing class of materials that offer great promise in various applications. However, the synthesis remains challenging: for example, a range of crystal structures can often be accessed from the same building blocks, which complicates the phase selectivity. Likewise, the high sensitivity to slight changes in synthesis conditions may cause reproducibility issues. This is crucial, as it hampers the research and commercialization of affected MOFs. Here, it presents the first-ever interlaboratory study of the synthetic reproducibility of two Zr-porphyrin MOFs, PCN-222 and PCN-224, to investigate the scope of this problem. For PCN-222, only one sample out of ten was phase pure and of the correct symmetry, while for PCN-224, three are phase pure, although none of these show the spatial linker order characteristic of PCN-224. Instead, these samples resemble dPCN-224 (disordered PCN-224), which has recently been reported. The variability in thermal behavior, defect content, and surface area of the synthesised samples are also studied. The results have important ramifications for field of metal-organic frameworks and their crystallization, by highlighting the synthetic challenges associated with a multi-variable synthesis space and flat energy landscapes characteristic of MOFs. It performed an interlaboratory study of the synthesis of the metal-organic frameworks (MOFs) PCN-222 and PCN-224. Ten participants independently synthesized the two MOFs and the products are analyzed, primarily by X-ray diffraction. The success rates are low (one-three samples corresponding to a pure sample of the correct phase), thus highlighting the problems with irreproducibility in MOF synthesis. image
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| 5. |
- Christensen, Kirsten E, et al.
(author)
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A germanate built from 68126 cavity co-templated by a (H2O)16 water cluster and 2-methylpiperazine
- 2008
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In: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 47:41, s. 7868-7871
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Journal article (peer-reviewed)abstract
- Totally tubular: A new tubular germanate is cotemplated by 2-methylpiperazine and an (H2O)16 cluster in a hydro(solvo)thermal synthesis. The germanate features a large, highly symmetric 68126 cavity (see picture; yellow sphere) built from 12 Ge7X19 (X=O, OH, F) clusters (GeX6 red, GeX5 yellow, GeX4 green).
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| 6. |
- Christensen, Kirsten E., et al.
(author)
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An open-framework silicogermanate with 26-ring channels built from seven-coordinated (Ge,Si)10(O, OH)28 clusters
- 2008
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 130:12, s. 3758-3759
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Journal article (peer-reviewed)abstract
- We report a new open-framework silicogermanate SU-61 containing 26-ring channels with a low framework density. It can be seen as a crystalline analogue to the mesoporous silica MCM-41. The structure is built from the assembly of (Ge,Si)10(O,OH)28 clusters. It is the first time that silicon has been successfully introduced in the Ge10 cluster in significant amounts (21% of the tetrahedral sites). Five- and six-coordinated Ge10 clusters have previously been observed in other germanate compounds leading to either dense or open structures. In SU-61, the seven-coordinated clusters fall onto yet another underlying net, the osf net. SU-61, along with other Ge10 based frameworks, shows the versatility of the germanate system to adopt defined topologies playing on the connectivity of the clusters following the principles of net decoration and scale chemistry.
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| 7. |
- Christensen, Kirsten E., et al.
(author)
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Open-framework germanates formed by the flexible Ge10 cluster
- 2008
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In: Zeolites and related materials: Trends, targets and challenges. - Amsterdam : Elsevier. - 9780444532978 ; , s. 317-320
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Conference paper (peer-reviewed)abstract
- Open-framework germanates have shown promising results in achieving extra-large pores and channels. Pores that extend to the mesoporous range (>20Å) were reported in SU-M. The structure of SU-M is built by the Ge10X28 (Ge10, X = O, OH, F) clusters. This cluster is also found in Ge-pharmacosiderite, Na4Ge9O20, ICMM-7 and SU-61. The Ge10 cluster has a flexibility to form compounds with both high and very low framework densities.
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| 8. |
- Guo, Bing, et al.
(author)
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Investigation of the GeO2-1,6-Diaminohexane-Water-Pyridine-HF Phase Diagram Leading to the Discovery of Two Novel Layered Germanates with Extra-Large Rings
- 2011
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In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 50:1, s. 201-207
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Journal article (peer-reviewed)abstract
- The systematic exploration of the phase diagram of the GeO2-1,6-diaminohexane-water-pyridine-HF system has allowed the identification of specific roles of the HF, H2O contents, and HF/H2O ratio in the formation of Ge7X19 (Ge7), Ge9X25−26 (Ge9), and Ge10X28 (Ge10) clusters (X = O, OH, F). This work has led to the discovery of two novel structures with extra-large 18-membered rings accommodating 1,6-diaminohexane (DAH): SU-63, |1.5H2DAH|[Ge7O14X3]·2H2O, a layered germanate constructed from Ge7 clusters with the Kagom topology, and SU-64, |11H2DAH|[Ge9O18X4][Ge7O14X3]6·16H2O, a germanate built of two-dimensional slabs containing both Ge7 and Ge9 clusters (X = OH or F). We also put SU-64 in context with previously reported cluster germanate compounds with related topologies by means of a simple crystal deconstruction study.
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| 9. |
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| 10. |
- Sun, Junliang, et al.
(author)
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The ITQ-37 mesoporous chiral zeolite
- 2009
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 458, s. 1154-1157
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Journal article (peer-reviewed)abstract
- The synthesis of crystalline molecular sieves with pore dimensions that fill the gap between microporous and mesoporous materials is a matter of fundamental and industrial interest. The preparation of zeolitic materials with extralarge pores and chiral frameworks would permit many new applications. Two important steps in this direction include the synthesis of ITQ-33, a stable zeolite with 18 × 10 × 10 ring windows, and the synthesis of SU-32, which has an intrinsically chiral zeolite structure and where each crystal exhibits only one handedness. Here we present a germanosilicate zeolite (ITQ-37) with extralarge 30-ring windows. Its structure was determined by combining selected area electron diffraction (SAED) and powder X-ray diffraction (PXRD) in a charge-flipping algorithm. The framework follows the SrSi2 (srs) minimal net and forms two unique cavities, each of which is connected to three other cavities to form a gyroidal channel system. These cavities comprise the enantiomorphous srs net of the framework. ITQ-37 is the first chiral zeolite with one single gyroidal channel. It has the lowest framework density (10.3 T atoms per 1,000 Å3) of all existing 4-coordinated crystalline oxide frameworks, and the pore volume of the corresponding silica polymorph would be 0.38 cm3 g-1. Keywords: srs-net, powder X-ray, charge flipping, electron microscopy
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