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A defining characteristic of nearly all catalytically functional MOFs is uniform, molecular-scale porosity. MOF pores, linkers and nodes that define them, help regulate reactant and product transport, catalyst siting, catalyst accessibility, catalyst stability, catalyst activity, co-catalyst proximity, composition of the chemical environment at and beyond the catalytic active site, chemical intermediate and transition-state conformations, thermodynamic affinity of molecular guests for MOF interior sites, framework charge and density of charge-compensating ions, pore hydrophobicity/hydrophilicity, pore and channel rigidity vs. flexibility, and other features and properties. Collectively and individually, these properties help define overall catalyst functional behaviour. This review focuses on how porous, catalyst-containing MOFs capitalize on molecular-scale confinement, containment, isolation, environment modulation, energy delivery, and mobility to accomplish desired chemical transformations with potentially superior selectivity or other efficacy, especially in comparison to catalysts in homogeneous solution environments.

Boron trifluoride (BF3) is a highly corrosive gas widely used in industry. Confining BF3 in porous materials ensures safe and convenient handling and prevents its degradation. Hence, it is highly desired to develop porous materials with high adsorption capacity, high stability, and resistance to BF3 corrosion. Herein, we designed and synthesized a Lewis basic single‐crystalline hydrogen‐bond crosslinked organic framework (HCOF‐50) for BF3 storage and its application in catalysis. Specifically, we introduced self‐complementary ortho‐alkoxy‐benzamide hydrogen‐bonding moieties to direct the formation of highly organized hydrogen‐bonded networks, which were subsequently photo‐crosslinked to generate HCOFs. The HCOF‐50 features Lewis basic thioether linkages and electron‐rich pore surfaces for BF3 uptake. As a result, HCOF‐50 shows a record‐high 14.2 mmol/g BF3 uptake capacity. The BF3 uptake in HCOF‐50 is reversible, leading to the slow release of BF3. We leveraged this property to reduce the undesirable chain transfer and termination in the cationic polymerization of vinyl ethers. Polymers with higher molecular weights and lower polydispersity were generated compared to those synthesized using BF3 ⋅ Et2O. The elucidation of the structure–property relationship, as provided by the single‐crystal X‐ray structures, combined with the high BF3 uptake capacity and controlled sorption, highlights the molecular understanding of framework‐guest interactions in addressing contemporary challenges. [ABSTRACT FROM AUTHOR]

The immobilization of H5PV2Mo10O40 polyoxometalates (POMs) in the in the mesoporous channel-type metal–organic framework (MOF), NU-1000, via simple impregnation method is reported here. Characterization of the composite PV2Mo10@NU-1000 activated by supercritical CO2 revealed that the POMs occupy the mesopore. Upon heating as low as 40 °C in the absence of bulk solvent, the POMs migrate to the micropore. However, the presence of solvent, such as cyclohexane, impedes this transformation. The material was active for the aerobic oxidation of the mustard gas simulant, 2-chloroethyl ethyl sulfide (CEES), in cyclohexane using isobutyraldehyde a sacrificial reductant and O2 as the oxidant. The activity of the POM allowed for efficient oxidation of CEES in the dark and in air. Immobilization of the POM in the MOF was found to improve the initial turnover frequency compared to the POM itself. Further, the POM catalyst was found to be unstable under the chosen reaction conditions and no activity was found upon washing and reusing the POM. As a composite PV2Mo10@NU-1000, the POMs retained their catalytic activity and allowed for recycling of the catalytic material. [ABSTRACT FROM AUTHOR]

The use of a dodecanuclear zirconium acetate cluster as a precursor enables the rapid, clean mechanochemical synthesis of high-microporosity metal–organic frameworks NU-901 and UiO-67, with surface areas up to 2250 m2 g−1. Real-time X-ray diffraction monitoring reveals that mechanochemical reactions involving the conventional hexanuclear zirconium methacrylate precursor are hindered by the formation of an inert intermediate, which does not appear when using the dodecanuclear acetate cluster as a reactant. [ABSTRACT FROM AUTHOR]

Abstract: NU‐1000 is a robust and highly porous Zr‐based metal–organic framework (Zr‐MOFs) that has been proven to be an excellent catalyst support because of its well‐defined crystal structure, protonic grafting sites on its nodes, and thermal stability, all of which advantageously offer the possibility to study the nature of the catalytic reactive sites. Herein, we present a vanadium‐oxide catalyst supported on NU‐1000 synthesized by solvothermal deposition in MOFs (SIM), namely, V‐NU‐1000. The catalytic activity of V‐NU‐1000 was investigated by studying the oxidation of 4‐methoxybenzyl alcohol under an O2 atmosphere; this catalyst showed higher conversion and higher selectivity than vanadium‐oxide supported on high‐surface‐area zirconia (V‐ZrO2). The stability of V‐NU‐1000 was confirmed by recyclability and leaching tests, in which recycled V‐NU‐1000 had catalytic ability comparable to that of the fresh catalyst, and no loss in the metal loading was found in recollected V‐NU‐1000. [ABSTRACT FROM AUTHOR]

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Metal-organic frameworks (MOFs) have gained considerable attention as hybrid materials-in part because of a multitude of potential useful applications, ranging from gas separation to catalysis and light harvesting. Unfortunately, de novo synthesis of MOFs with desirable function-property combinations is not always reliable and may suffer from vagaries such as formation of undesirable topologies, low solubility of precursors, and loss of functionality of the sensitive network components. The recently discovered synthetic approach coined solvent-assisted linker exchange (SALE) constitutes a simple to implement strategy for circumventing these setbacks; its use has already led to the generation of a variety of MOF materials previously unobtainable by direct synthesis methods. This Review provides a perspective of the achievements in MOF research that have been made possible with SALE and examines the studies that have facilitated the understanding and broadened the scope of use of this invaluable synthetic tool. [ABSTRACT FROM AUTHOR]

Inspired by biology, in which a bimetallic hydroxide-bridged zinc(II)-containing enzyme is utilized to catalytically hydrolyze phosphate ester bonds, the utility of a zirconium(IV)-cluster-containing metal-organic framework as a catalyst for the methanolysis and hydrolysis of phosphate-based nerve agent simulants was examined. The combination of the strong Lewis-acidic ZrIV and bridging hydroxide anions led to ultrafast half-lives for these solvolysis reactions. This is especially remarkable considering that the actual catalyst loading was a mere 0.045 % as a result of the surface-only catalysis observed. [ABSTRACT FROM AUTHOR]

On account of their structural similarity to cofactors found in many metallo-enzymes, metalloporphyrins are obvious potential building blocks for catalytically active, metal-organic framework (MOF) materials. While numerous porphyrin-based MOFs have already been described, versions featuring highly accessible active sites and permanent microporosity are remarkably scarce. Indeed, of the more than 70 previously reported porphyrinic MOFs, only one has been shown to be both permanently microporous and contain internally accessible active sites for chemical catalysis. Attempts to generalize the design approach used in this single successful case have failed. Reported here, however, is the synthesis of an extended family of MOFs that directly incorporate a variety of metalloporphyrins (specifically Al3+, Zn2+, Pd2+, Mn3+, and Fe3+ complexes). These robust porphyrinic materials (RPMs) feature large channels and readily accessible active sites. As an illustrative example, one of the manganese-containing RPMs is shown to be catalytically competent for the oxidation of alkenes and alkanes. [ABSTRACT FROM AUTHOR]

The article presents a study where a noncatenated hydroxyl-functionalized metal-organic framework (MOF) material was introduced as method for integrating unsaturated metal ions in hydrogen sorption. The study revealed single network cavities-containing with available alcohol qualities through single-crystal X-ray measurement. Additionally, it imparts that the approach may also be desirable for metals that facilitate chemical catalysis or separations.

The article underscores supercritical processing as a route to high internal surface areas and permanent microporosity in metal-organic framework materials. It states that crystalline metal-organic frameworks (MOFs) have evolved as attractive materials for a wide consideration of possible applications, including chemical separations, chemical fuel storage and release, and size-selective molecular catalysis.

Review: 79 refs. [ABSTRACT FROM AUTHOR]

Few-atom cobalt-oxide clusters, when dispersed on a Zr-based metal-organic framework (MOF) NU-1000, have been shown to be active for the oxidative dehydrogenation (ODH) of propane at low temperatures (<230 °C), affording a selective and stable propene production catalyst. In our current work, a series of promoter ions with varying Lewis acidity, including Ni(II), Zn(II), Al(III), Ti(IV) and Mo(VI), are anchored as metal-oxide,hydroxide clusters to NU-1000 followed by Co(II) ion deposition, yielding a series of NU-1000-supported bimetallic-oxo,hydroxo,aqua clusters. Using difference envelope density (DED) analyses, the spatial locations of the promoter ions and catalytic cobalt ions are determined. For all samples, the promoter ions are sited between pairs of Zr6 nodes along the MOF c-axis, whereas the location of the cobalt ions varies with the promoter ions. These NU-1000- supported bimetallic-oxide clusters are active for propane ODH after thermal activation under O2 to open a cobalt coordination site and to oxidize Co(II) to Co(III), as evidenced by operando X-ray absorption spectroscopy at the Co K-edge. In accord with the decreasing Lewis acidity of the promoter ion, catalytic activity increases in the following order: Mo(VI) < Ti(IV) < Al(III) < Zn(II) < Ni(II). The finding is attributed to increasing ease of formation of Co(III)−O• species and stabilization of a cobalt(III)- oxyl/propane transition state as the Lewis acidity of the promoter ions decreases. The results point to an increasing ability to fine-tune the structure-dependent activity of MOF-supported heterogeneous catalysts. Coupled with mechanistic studies-- computational or experimental--this ability may translate into informed prediction of improved catalysts for propane ODH and other chemical reactions. [ABSTRACT FROM AUTHOR]

Since sulfur mustard was first used in World War I, significant efforts have been made in materials and methods development for the adsorption and detoxification of different classes of chemical warfare agents (CWAs). Considering the importance of efficiency and safety in this process, catalytic degradation is a viable approach for fast and complete detoxification of CWAs. To date, a variety of catalysts have been discovered to be active for the degradation of nerve agents and sulfur mustard. Among the most promising are a class of porous functional materials named metal-organic frameworks (MOFs). In the past few years, tremendous progress has been made in this field including the discovery of zirconium MOF catalysts for fast nerve agent hydrolysis. In this review, we summarize recent advances in the development of MOF catalysts for the hydrolysis of nerve agents as well as the oxidation of sulfur mustard. Dual function MOF catalysts, i.e. catalysts that can detoxify nerve agents and sulfur mustard simultaneously, are also discussed. [ABSTRACT FROM AUTHOR]

This manuscript demonstrates the synthesis of selective Lewis-acid sites in a metal-organic framework (MOF) for glucose transformation to 5-hydroxymethylfurfural (HMF). These sites are synthesized via partial phosphate modification of zirconia-cluster nodes in MOF NU-1000, which titrates strong Lewis-acid sites that would lead to undesired side reactions. Our mechanistic study using isotope tracer analysis and kinetic isotope effect measurements reveals that an isomerization-dehydration mechanism mainly occurs on the MOF catalyst, where fructose is an intermediate. This mechanism suggests that dilute concentrations are favorable in order to suppress undesired intermolecular condensation of glucose/fructose/HMF and maximize HMF yield. We demonstrate both high yield and selectivity of HMF formation of 64% with the MOF catalyst, at an initial glucose concentration of 1 mM in water/2-propanol. In stark contrast, similar partial phosphate modification of a bulk zirconia yields a catalyst that exhibits poor HMF selectivity, while possessing nearly identical Brnsted acidity to the selective NU-1000-based catalyst. [ABSTRACT FROM AUTHOR]

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 facilitates the determination of the identity and chemistry of the functional groups on MOF node vacancies and defect sites. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate that the incorporation of an acidic hydrogen-bond-donating squaramide moiety into a porous UiO-67 metal--organic framework (MOF) derivative leads to dramatic acceleration of the biorelevant Friedel--Crafts reaction between indole and β-nitrostyrene. In comparison, it is shown that free squaramide derivatives, not incorporated into MOF architectures, have no catalytic activity. Additionally, using the UiO-67 template, we were able to perform a direct comparison of catalytic activity with that of the less acidic urea-based analogue. This is the first demonstration of the functionalization of a heterogeneous framework with an acidic squaramide derivative. [ABSTRACT FROM AUTHOR]

• Porphyrins are important molecules as enzyme active sites and visible light absorption units. • Porphyrin-based MOFs can isolate and provide access to the inherent properties of porphyrins. • The field of porphyrinic MOFs has evolved from structural explorations to various applications. • Applications of porphyrinic MOFs in catalysis, sensing and biomedicines have been highlighted. Porphyrins are important molecules widely found in nature in the form of enzyme active sites and visible light absorption units. Recent interest in using these functional molecules as building blocks for the construction of metal–organic frameworks (MOFs) have rapidly increased due to the ease in which the locations of, and the distances between, the porphyrin units can be controlled in these porous crystalline materials. Porphyrin-based MOFs with atomically precise structures provide an ideal platform for the investigation of their structure–function relationships in the solid state without compromising accessibility to the inherent properties of the porphyrin building blocks. This review will provide a historical overview of the development and applications of porphyrin-based MOFs from early studies focused on design and structures, to recent efforts on their utilization in biomimetic catalysis, photocatalysis, electrocatalysis, sensing, and biomedical applications. [ABSTRACT FROM AUTHOR]

The article offers information on catalysis that had a transformative impact on society, playing a crucial role in the production of modern materials, medicines, fuels, and chemicals. Topics include examines that metals have been the cornerstone of many industrial catalytic processes for decades, providing high activity, stability, and tolerance to poisons and in stark contrast, redox catalysis essential to life is carried out by metalloenzymes that feature Earth-abundant metals.