Brønsted Acidity in Metal–Organic Frameworks

Jiang, Juncong; Yaghi, Omar M.

doi:10.1021/acs.chemrev.5b00221

Cited by 511 publications

(315 citation statements)

References 256 publications

(476 reference statements)

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“…The uniform structures of the MOFs allow unprecedentedly precise control of surfaces with these groups, which are essential for some separations by adsorption, 9 for catalysis, and for anchoring of metal complexes.…”

Section: Resultsmentioning

confidence: 99%

Tuning the Surface Chemistry of Metal Organic Framework Nodes: Proton Topology of the Metal-Oxide-Like Zr₆ Nodes of UiO-66 and NU-1000

et al. 2016

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Some metal organic frameworks (MOFs) incorporate nodes that are nanoscale metal oxides, and the hydroxy-containing functional groups on them provide opportunities for introducing catalytic sites with precisely defined structures. Investigations have been done to understand the structures of these groups on nodes and node vacancies, because, in prospect, atomic-scale modulation of the composition, areal density, and/or siting of the groups would open up possibilities for exquisite tuning of the siting and performance of subsequently anchored catalytic units (e.g., single metal ions, pairs of metal ions, or well defined metal-ion-containing clusters). We have combined infrared (IR) spectroscopy and density functional theory (DFT) to demonstrate tuning of these sites, namely, hydrogen-bonded OH/OH2 groups on the Zr6 nodes of the MOFs UiO-66 and NU-1000 via the intermediacy of node methoxy (or ethoxy) groups formed from methanol (or ethanol). Methoxy (or ethoxy) groups on node vacancy sites are converted to a structure incorporating one vacant Zr site and one terminal OH group per face by reaction with water. Our results highlight how the combination of DFT and IR spectroscopy facilitate the determination of the identity and chemistry of the functional groups on MOF node vacancies and defect sites. INTRODUCTIONThe nodes of some metal-organic frameworks (MOFs) are essentially small, uniform metal oxide clusters, exemplified by the Zr6 nodes of

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Section: Resultsmentioning

confidence: 99%

Tuning the Surface Chemistry of Metal Organic Framework Nodes: Proton Topology of the Metal-Oxide-Like Zr₆ Nodes of UiO-66 and NU-1000

et al. 2016

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“…Moreover, ILs exhibit high ionic conductivity and wide electrochemical windows and consequently are promising electrolytes for a wide variety of electrochemical devices, such as rechargeable batteries, supercapacitors, dye-sensitized solar cells, and thermoelectric cells. 5 Metal organic frameworks [6][7][8][9][10][11][12][13][14] (MOFs) are a rather new member of the family of porous materials. MOF materials combine metal-based nodes with organic linkers to build hybrid porous crystalline networks with high surface area and large pore volume.…”

Section: Introductionmentioning

confidence: 99%

Removal of Confined Ionic Liquid from a Metal Organic Framework by Extraction with Molecular Solvents

et al. 2017

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Hybrid materials of ionic liquids (IL) confined in metal organic frameworks (MOF) are promising materials for energy storage. The effects of exposing or treating such composite materials with molecular solvents, e.g. with the aim to extract and replace the IL, have not been studied to date. In this study, acetone, isopropanol, methanol, and water were used to remove the IL 1-ethyl-3-methylimidazolium ethyl sulfate confined in a Cu-based metal organic framework (CuBTC). The consequences of the solvent extraction process were analyzed using vibrational spectroscopy (FTIR), powder X-ray diffraction (PXRD), N 2 adsorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Methanol was identified as the best solvent for IL removal as it shows high extraction efficiency without affecting the porous geometry and crystal structure of the MOF. On the other hand, acetone and isopropanol were not able to completely remove the IL from CuBTC under the conditions employed. Water effectively removed the IL, but it has a significant detrimental effect on the CuBTC structure.This impact manifests as changes in the infrared spectra and the PXRD patterns as well as in the electron micrographs. The degraded CuBTC exhibits a non-porous structure that presents itself as non-uniformly agglomerated micro-rods along with very few hexagonal/amorphous phases.The confinement of acetone, isopropanol, and methanol in the MOF was also investigated. The results show that CuBTC is stable in acetone, isopropanol, and methanol but unstable in water.

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“…The diversity of metal cluster SBUs offers an alternative strategy for generating MOF catalysts. Although MOF SBUs have been used as acid catalysts2425, their application in more challenging catalytic reactions or as potential supports for catalysis has been far less explored2627.…”

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confidence: 99%

Chemoselective single-site Earth-abundant metal catalysts at metal–organic framework nodes

et al. 2016

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Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal–organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C–H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

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Brønsted Acidity in Metal–Organic Frameworks

Abstract: Aspartate (b) and MIL-100 (c); and Brønsted Acidity Introduced through PSM in IRMOF-3 (d), DO-MOF (e), UMCM-1-NH 2 (f), UiO-66 (g), MIL-53 (h), and MIL-101 (i) a a Tf 2 O = triflic anhydride; RT = room temperature.

Cited by 511 publications

References 256 publications

Tuning the Surface Chemistry of Metal Organic Framework Nodes: Proton Topology of the Metal-Oxide-Like Zr₆ Nodes of UiO-66 and NU-1000

Tuning the Surface Chemistry of Metal Organic Framework Nodes: Proton Topology of the Metal-Oxide-Like Zr₆ Nodes of UiO-66 and NU-1000

Removal of Confined Ionic Liquid from a Metal Organic Framework by Extraction with Molecular Solvents

Chemoselective single-site Earth-abundant metal catalysts at metal–organic framework nodes

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Brønsted Acidity in Metal–Organic Frameworks

Abstract: Aspartate (b) and MIL-100 (c); and Brønsted Acidity Introduced through PSM in IRMOF-3 (d), DO-MOF (e), UMCM-1-NH 2 (f), UiO-66 (g), MIL-53 (h), and MIL-101 (i) a a Tf 2 O = triflic anhydride; RT = room temperature.

Cited by 511 publications

References 256 publications

Tuning the Surface Chemistry of Metal Organic Framework Nodes: Proton Topology of the Metal-Oxide-Like Zr6 Nodes of UiO-66 and NU-1000

Tuning the Surface Chemistry of Metal Organic Framework Nodes: Proton Topology of the Metal-Oxide-Like Zr6 Nodes of UiO-66 and NU-1000

Removal of Confined Ionic Liquid from a Metal Organic Framework by Extraction with Molecular Solvents

Chemoselective single-site Earth-abundant metal catalysts at metal–organic framework nodes

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Product

Resources

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Tuning the Surface Chemistry of Metal Organic Framework Nodes: Proton Topology of the Metal-Oxide-Like Zr₆ Nodes of UiO-66 and NU-1000

Tuning the Surface Chemistry of Metal Organic Framework Nodes: Proton Topology of the Metal-Oxide-Like Zr₆ Nodes of UiO-66 and NU-1000