NMR‐Untersuchungen zur Diffusion von Kohlenwasserstoffen im metall‐organischen Netzwerk MOF‐5

Stallmach, Frank; Gröger, Stefan; Künzel, Volker; Kärger, Jörg; Yaghi, Omar M.; Hesse, M.; Müller, Ulrich

doi:10.1002/ange.200502553

Cited by 36 publications

(22 citation statements)

References 21 publications

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“…In recent work, we found an agreement between the results of PFG NMR [26] and MD simulations [13] at 298 K at a relatively low loading of six benzene molecules per unit cell of MOF-5. Later MD simulations predicted at 298 K a slightly increasing diffusivity for loadings up to about 32 molecules per unit cell which then falls off at higher loadings [27].…”

Section: Introductionsupporting

confidence: 74%

NMR studies of benzene mobility in metal-organic framework MOF-5

Hertel

Wehring

Amirjalayer

et al. 2011

Eur. Phys. J. Appl. Phys.

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Abstract. The concentration and temperature dependence of the self-diffusion of benzene adsorbed in the metal-organic framework MOF-5 (IRMOF-1) is studied by pulsed field gradient (PFG) NMR spectroscopy.When increasing the loading from 10 to 20 molecules per unit cell of MOF-5, the experimental diffusion data drop by a factor of about three while current molecular dynamic (MD) simulations predict slightly increasing diffusion coefficients for this range of loadings. The observation is rationalized using the recently predicted clustering of adsorbate molecules in microporous systems for temperatures well below the adsorbate critical temperature. Necessary improvements of molecular simulation models for predicting diffusivities under such conditions are discussed.

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Section: Introductionsupporting

confidence: 74%

NMR studies of benzene mobility in metal-organic framework MOF-5

Hertel

Wehring

Amirjalayer

et al. 2011

Eur. Phys. J. Appl. Phys.

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“…[9,14] In addition to predicting macroscopic observables, simulations can also provide useful molecular-level insights. To systematically investigate the thermal properties of MOFs, we herein simulate the (cubic) structures of several IRMOFs of varying linker length.…”

mentioning

confidence: 99%

Exceptional Negative Thermal Expansion in Isoreticular Metal–Organic Frameworks

et al. 2007

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The thermal-expansion properties [1] of substances are very important in materials design; for example, cracks form when joined materials expand or contract by different amounts upon heating. The most famous example of a substance that contracts when heated is ice: it transforms into water, which has a higher density than ice. Negative thermal expansion (NTE) in solids is relatively rare, although examples have been found in zeolites.[2] The underlying physics of NTE remains poorly understood. Herein, we show, on the basis of molecular simulations, that the recently synthesized isoreticular metal-organic frameworks (IRMOFs) consistently have negative thermal-expansion coefficients and are by far the most contracting materials known. Our simulations point to two competing effects: a local effect, where all bond lengths increase with temperature, and a second long-range effect, where the thermal movement of the linker molecules leads to a shorter average distance between corners upon heating.MOFs are a new class of nanoporous materials that have good stability, large void volumes, and well-defined tailorable cavities of uniform size. Their potential appears great, because these are precisely the properties needed for catalysis, separations, and storage/release applications. [3] MOFs generally consist of metal or metal-oxygen vertices interconnected by rigid or semirigid organic molecules. A large variety of MOFs, featuring different linker molecules and different types of bonding between the vertices with the linkers, have been produced by various research groups. The specific examples shown in Figure 1 are IRMOFs developed by Yaghi and co-workers. [4][5][6][7][8] In general, the IRMOFs consist of zinc-oxygen complexes connected by carboxylate-terminated linkers, forming a three-dimensional lattice of cubic cavities.Molecular simulations of adsorption in MOFs have shown very good agreement with experiment, [9][10][11][12][13] and it is interesting to note that simulations of diffusion in MOFs preceded experiments by almost two years. [9,14] In addition to predicting macroscopic observables, simulations can also provide useful molecular-level insights. To systematically investigate the thermal properties of MOFs, we herein simulate the (cubic) structures of several IRMOFs of varying linker length. We obtain information about the unit-cell length (L) as a function of temperature and about adsorbate loadings (q) as a function of pressure. We show that the experimental data scattered in the literature (for different adsorbate loadings and temperatures) are, in fact, consistent, and we elucidate the different effects of temperature and loading on L at the microscopic level.Various models for MOF flexibility have recently appeared. [15][16][17] Our flexible framework model for IRMOF-1, IRMOF-10, and IRMOF-16 is described in the Supporting Information. It is similar in spirit to the model of Greathouse and Allendorf, [15] but differs in the treatment of the carboxylate group and has the advantage of being calibrated to ex...

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“…From an experimental standpoint, only pulsed field gradient (PFG) NMR diffusion measurements have been reported on various hydrocarbons in MOF‐5, including methane at high loading 19. Quasi‐elastic neutron scattering (QENS) measurements have given detailed molecular‐level information on the diffusion of various adsorbates in nanoporous materials 20.…”

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confidence: 99%

Quasi‐Elastic Neutron Scattering and Molecular Dynamics Study of Methane Diffusion in Metal Organic Frameworks MIL‐47(V) and MIL‐53(Cr)

et al. 2008

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Kanalflutung: Die Diffusion von Methan in den metall‐organischen Gerüsten MIL‐53(Cr) und MIL‐47(V) wurde durch quasielastische Neutronenbeugung und Moleküldynamiksimulationen aufgeklärt; dabei wurde in beiden Materialien eine eindimensionale Diffusion von CH4 entlang der Kanäle beobachtet. Der Eigendiffusionskoeffizient von Methan bei niedriger Beladung liegt um mehr als eine Größenordnung über dem in Zeolithen. Das Bild zeigt CH4‐Moleküle in einem MIL‐53(Cr)‐Kanal.

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NMR‐Untersuchungen zur Diffusion von Kohlenwasserstoffen im metall‐organischen Netzwerk MOF‐5

Cited by 36 publications

References 21 publications

NMR studies of benzene mobility in metal-organic framework MOF-5

NMR studies of benzene mobility in metal-organic framework MOF-5

Exceptional Negative Thermal Expansion in Isoreticular Metal–Organic Frameworks

Quasi‐Elastic Neutron Scattering and Molecular Dynamics Study of Methane Diffusion in Metal Organic Frameworks MIL‐47(V) and MIL‐53(Cr)

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