Are Zr<sub>6</sub>-based MOFs water stable? Linker hydrolysis vs. capillary-force-driven channel collapse

Mondloch, Joseph E.; Katz, Michael J.; Planas, Nora; Semrouni, David; Gagliardi, Laura; Hupp, Joseph T.; Farha, Omar K.

doi:10.1039/c4cc02401j

Cited by 299 publications

(258 citation statements)

References 30 publications

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“…19 Molecules diffusing in NU-1000 encounter topologically infinite channels of two distinct sizes: one-dimensional mesopores with a pore diameter of 30Å and smaller one-dimensional micropores with 8Å pore diameter ( Figure 1). While the parallel alignment of the channels drives one dimensional diffusion along the channel axes, interconnecting pathways between the channels permit diffusing molecules to transit between the channels.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneous Diffusion of Alkanes in the Hierarchical Metal–Organic Framework NU-1000

Vargas

Snurr

2015

Langmuir

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The metal-organic framework (MOF) NU-1000 is a hierarchical material that comprises both micropores and mesopores in its crystalline structure. Because the pore structure is perfectly defined, NU-1000 is an interesting material for improving our understanding of diffusion in hierarchically structured materials. Here, we present molecular dynamics simulations aimed at probing the transport properties of n-alkanes in NU-1000 and introduce methods from the microrheology literature for analyzing the mean-squared displacements and their spatial heterogeneity. Adsorption occurs initially in the smaller channels, and diffusion at low loading is limited by interaction between adsorbate and framework atoms. The larger channels provide a region of low density where molecules are able to diffuse at higher rates predominantly along the channel axes. The disparate size of the channels gives rise to heterogeneity in the diffusivity of the guest molecules, whereas the asymmetry of the channels leads to anisotropic diffusion. Together, the channels form a network of "highways" and "side streets" that provide enhanced diffusion in one dimension.

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Section: Introductionmentioning

confidence: 99%

Heterogeneous Diffusion of Alkanes in the Hierarchical Metal–Organic Framework NU-1000

Vargas

Snurr

2015

Langmuir

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“…Because MOFs are constructed from metal ions or clusters and organic linkers connected by coordination bonds, they are often sensitivet oc ertain reaction conditions. Whereas studies on the water stabilityo fM OFs are abundant, [53][54][55][56] similars ystematici nvestigations of their stability with different bases (i.e.,c onditions relevant for Suzuki-Miyaura coupling reactions) are lacking. The behaviour of the support in catalysis is important to reduce metal leaching, which is essential for the synthesis of pharmaceuticals.…”

Section: Introductionmentioning

confidence: 99%

Influence of the Base on Pd@MIL‐101‐NH₂(Cr) as Catalyst for the Suzuki–Miyaura Cross‐Coupling Reaction

Carson

Paşcanu

Gómez

et al. 2015

Chemistry A European J

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The chemical stability of metal-organic frameworks (MOFs) is a major factor preventing their use in industrial processes. Herein, it is shown that judicious choice of the base for the Suzuki-Miyaura cross-coupling reaction can avoid decomposition of the MOF catalyst Pd@MIL-101-NH2 (Cr). Four bases were compared for the reaction: K2 CO3 , KF, Cs2 CO3 and CsF. The carbonates were the most active and achieved excellent yields in shorter reaction times than the fluorides. However, powder XRD and N2 sorption measurements showed that the MOF catalyst was degraded when carbonates were used but remained crystalline and porous with the fluorides. XANES measurements revealed that the trimeric chromium cluster of Pd@MIL-101-NH2 (Cr) is still present in the degraded MOF. In addition, the different countercations of the base significantly affected the catalytic activity of the material. TEM revealed that after several catalytic runs many of the Pd nanoparticles (NPs) had migrated to the external surface of the MOF particles and formed larger aggregates. The Pd NPs were larger after catalysis with caesium bases compared to potassium bases.

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“…polymorphs NU-901 and NU-1000, exhibit high porosity, chemical stability and conductivity, simultaneously, making these suitable for electrochemical device applications. 8,18,[38][39][40] Depending on the application, additional material requirements besides charge transport include energy transport, [41][42][43] optical response [44][45][46] and catalytic activity. 13 The catalytic activity of MOFs has been studied for a variety of reactions, including oxidation, hydrogenation and condensation reactions.…”

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confidence: 99%

Theoretical Investigation of Charge Transfer in Metal Organic Frameworks for Electrochemical Device Applications

Patwardhan

Schatz

2015

J. Phys. Chem. C

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For electrochemical device applications metal organic frameworks (MOFs) must exhibit suitable conduction properties. To this end, we have performed computational studies of intermolecular charge transfer in MOFs consisting of hexa-Zr IV nodes and tetratopic carboxylate linkers. This includes an examination of the electronic structure of linkers that are derived from tetraphenyl benzene 1, tetraphenyl pyrene 2 and tetraphenyl porphyrin 3 molecules. These results are used to determine charge transfer propensities in MOFs, within the framework of Marcus theory, including an analysis of the key parameters (charge transfer integral t, reorganization energy λ and free energy change ∆G 0 ), and evaluation of figures of merit for charge transfer based on the chemical structures of the linkers. This qualitative analysis indicates that delocalization of the HOMO/LUMO on terminal substituents increases t and decreases λ, while weaker binding to counterions decreases ∆G 0 , leading to better charge transfer propensity. Subsequently, we study hole transfer in the linker 2 containing MOFs, NU-901 and NU-1000, in detail and describe mechanisms (hopping and superexchange) that may be operative under different electrochemical conditions. Comparisons with experiment are provided whereavailable. Based on the redox and catalytic activity of nodes and linkers, we propose three possible schemes for constructing electrochemical devices for catalysis. We believe that the results of this study will lay the foundation for future experimental work on this topic.

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Are Zr₆-based MOFs water stable? Linker hydrolysis vs. capillary-force-driven channel collapse

Cited by 299 publications

References 30 publications

Heterogeneous Diffusion of Alkanes in the Hierarchical Metal–Organic Framework NU-1000

Heterogeneous Diffusion of Alkanes in the Hierarchical Metal–Organic Framework NU-1000

Influence of the Base on Pd@MIL‐101‐NH₂(Cr) as Catalyst for the Suzuki–Miyaura Cross‐Coupling Reaction

Theoretical Investigation of Charge Transfer in Metal Organic Frameworks for Electrochemical Device Applications

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Are Zr6-based MOFs water stable? Linker hydrolysis vs. capillary-force-driven channel collapse

Cited by 299 publications

References 30 publications

Heterogeneous Diffusion of Alkanes in the Hierarchical Metal–Organic Framework NU-1000

Heterogeneous Diffusion of Alkanes in the Hierarchical Metal–Organic Framework NU-1000

Influence of the Base on Pd@MIL‐101‐NH2(Cr) as Catalyst for the Suzuki–Miyaura Cross‐Coupling Reaction

Theoretical Investigation of Charge Transfer in Metal Organic Frameworks for Electrochemical Device Applications

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Are Zr₆-based MOFs water stable? Linker hydrolysis vs. capillary-force-driven channel collapse

Influence of the Base on Pd@MIL‐101‐NH₂(Cr) as Catalyst for the Suzuki–Miyaura Cross‐Coupling Reaction