Encapsulation of an organometallic cationic catalyst by direct exchange into an anionic MOF

Assembly of an iron-based complex into a metal-organic framework: a space confinement strategy for isolation of mono-iron complexes to protect from dimerization

Non-heme mononuclear iron complexes, especially when supported by tripodal tetradentate ligands, show promising C-H bond activation efficiency in catalytic reactions. Nevertheless, they intrinsically decay readily to their dinuclear form, and the dimerization process is inevitable in homogenous solution, which dramatically hinders their further application. Hence, we demonstrate that the mononuclear iron complex [(TPA)FeII-2L]2+ (L = labile ligands, mainly solvent molecules) was successfully encapsulated in a highly robust metal-organic framework UiO-66 via a two-step "ship-in-a-bottle" strategy. The nearly perfect size matching of the octahedral cages of the host UiO-66 provides ideal space confinement for the guest complex to protect from dimerization and dramatically increases the mono-nuclear complex stability compared to its un-confined state. The successful encapsulation of [(TPA)FeII-2L]2+ in UiO-66 was verified thoroughly by spectroscopy, microscopy, N2 adsorption, and electrochemistry characterization techniques. This work shows that encapsulating an unstable molecular complex in MOFs via a two-step "ship-in-a-bottle" strategy highlights opportunities for extending the heterogenization of homogeneous complexes.

Characterization of an unanticipated indium-sulfur metallocycle complex

We have produced a novel indium-based metallocycle complex (In-MeSH), which we initially observed as an unanticipated side-product in metal-organic framework (MOF) syntheses. The serendipitously synthesized metallocycle forms via the acid-catalysed decomposition of dimethyl sulfoxide (DMSO) during solvothermal reactions in the presence of indium nitrate, dimethylformamide and nitric acid. A search through the Cambridge Structural Database revealed isostructural zinc, ruthenium and palladium metallocycle complexes formed by other routes. The ruthenium analogue is catalytically active and the In-MeSH structure similarly displays accessible open metal sites around the outside of the ring. Furthermore, this study also gives access to the relatively uncommon oxidation state of In(II), the targeted synthesis of which can be challenging. In(II) complexes have been reported as having potentially important applications in areas such as catalytic water splitting.

Co-generation of palladium nanoparticles and phosphate supported on metal-organic frameworks as hydrogenation catalysts

In this study, we demonstrated the direct synthesis of sodium dihydrogen phosphate (PA) containing palladium nanoparticles (PdNPs) supported on a metal-organic framework (MOF). The resulting composite containing PA molecules coexisting with PdNPs demonstrated improved hydrogenation catalytic performance compared to the composites without PA.

Bioinspired Framework Catalysts: From Enzyme Immobilization to Biomimetic Catalysis

Enzymatic catalysis has fueled considerable interest from chemists due to its high efficiency and selectivity. However, the structural complexity and vulnerability hamper the application potentials of enzymes. Driven by the practical demand for chemical conversion, there is a long-sought quest for bioinspired catalysts reproducing and even surpassing the functions of natural enzymes. As nanoporous materials with high surface areas and crystallinity, metal-organic frameworks (MOFs) represent an exquisite case of how natural enzymes and their active sites are integrated into porous solids, affording bioinspired heterogeneous catalysts with superior stability and customizable structures. In this review, we comprehensively summarize the advances of bioinspired MOFs for catalysis, discuss the design principle of various MOF-based catalysts, such as MOF-enzyme composites and MOFs embedded with active sites, and explore the utility of these catalysts in different reactions. The advantages of MOFs as enzyme mimetics are also highlighted, including confinement, templating effects, and functionality, in comparison with homogeneous supramolecular catalysts. A perspective is provided to discuss potential solutions addressing current challenges in MOF catalysis.

Direct generation of polypyrrole-coated palladium nanoparticles inside a metal-organic framework for a semihydrogenation catalyst

Herein, the direct synthesis of polypyrrole (PPy)-coated palladium nanoparticles (PdNPs) inside a metal-organic framework (MIL-101) was successfully demonstrated. Owing to the PPy coating of PdNPs, the resulting composites exhibited higher semihydrogenation capability (selectivity: up to 96%) than the analog composite without PPy coating.

Ionic metal-organic frameworks (iMOFs): progress and prospects as ionic functional materials

Metal-organic frameworks (MOFs) have been a research hotspot for the last two decades, witnessing an extraordinary upsurge across various domains in materials chemistry. Ionic MOFs (both anionic and cationic MOFs) have emerged as next-generation ionic functional materials and are an important subclass of MOFs owing to their ability to generate strong electrostatic interactions between their charged framework and guest molecules. Furthermore, the presence of extra-framework counter-ions in their confined nanospaces can serve as additional functionality in these materials, which endows them a significant advantage in specific host-guest interactions and ion-exchange-based applications. In the present review, we summarize the progress and future prospects of iMOFs both in terms of fundamental developments and potential applications. Furthermore, the design principles of ionic MOFs and their state-of-the-art ion exchange performances are discussed in detail and the future perspectives of these promising ionic materials are proposed.

Ionic encapsulation of a methanol carbonylation catalyst in a microporous metal-organic framework

The anionic rhodium complex cis-[Rh(CO)₂I₂]^-, active in the Monsanto process for acetic acid production, has been heterogenised via Coulombic interactions in the pores of a UiO-66-type metal-organic framework (MOF). The MOF-supported catalyst is active for the carbonylation of methanol and is recyclable, retaining its framework crystallinity following catalysis. Intermediates in the catalytic cycle observed by IR spectroscopy confirm the same mechanism as the established homogeneous process.

Cooperative catalysis in a metal-organic framework via post-synthetic immobilisation

Herein, we generated a series of cooperative catalysts via post-synthetic immobilisation of a Co(salen) complex in a metal-organic framework (MOF). By tuning the amount of Co(salen) in the MOF, the cooperative catalytic activities can be successfully optimised.

Catalytic oxygen evolution from hydrogen peroxide by trans-[Co(en)2Cl2]@InBTB metal-organic framework catalytic system

The diethylammonium counter-cations of the [Et2NH2]3[In3(BTB)4] metal-organic framework (InBTB MOF, BTB = 1,3,5-benzenetribenzoate) with an anionic framework can be effectively exchanged with cationic trans-[Co(en)2Cl2]+ complex ions through a simple cation-exchange process. The heterogenized trans-[Co(en)2Cl2]+-encapsulated InBTB MOF (trans-[Co(en)2Cl2]@InBTB) catalytic system maintained the activity of the captured trans-[Co(en)2Cl2]+ complex ion for hydrogen peroxide decomposition in aqueous solution under mild reaction conditions. The captured trans-[Co(en)2Cl2]+ complex also exhibited trans-cis isomerization to produce either cis-[Co(en)2Cl2]@InBTB or cis-[Co(en)2(H2O)Cl]@InBTB based on IR spectroscopic investigation. The trans-[Co(en)2Cl2]@InBTB catalytic system showed high recyclability for oxygen evolution from hydrogen peroxide. The catalytic ability of trans-[Co(en)2Cl2]@InBTB was maintained up to seven times of recycling.

Anion-Afforded Functions of Ionic Metal-Organic Frameworks: Ionochromism, Anion Conduction, and Catalysis

The exchangeable counterions in ionic metal-organic frameworks (IMOFs) provide facile and versatile handles to manipulate functions associated with the ionic guests themselves and host-guest interactions. However, anion-exchangeable stable IMOFs combining multiple anion-related functions are still undeveloped. In this work, a novel porous IMOF featuring unique self-penetration was constructed from an electron-deficient tris(pyridinium)-tricarboxylate zwitterionic ligand. The water-stable IMOF undergoes reversible and single-crystal-to-single-crystal anion exchange and shows selective and discriminative ionochromic behaviors toward electron-rich anions owing to donor-acceptor interactions. The IMOFs with different anions are good ionic conductors with low activation energy, the highest conductivity being observed with chloride. Furthermore, integrating Lewis acidic sites and nucleophilic guest anions in solid state, the IMOFs act as heterogeneous and recyclable catalysts to efficiently catalyze the cycloaddition of CO₂ to epoxides without needing the use of halide cocatalysts. The catalytic activity is strongly dependent upon the guest anions, and the iodide shows the highest activity. The results demonstrate the great potential of developing IMOFs with various functions related to the guest ions included in the porous matrices.

MOF-enabled confinement and related effects for chemical catalyst presentation and utilization

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.

Tailoring Heterogeneous Catalysts at the Atomic Level: In Memoriam, Prof. Chia-Kuang (Frank) Tsung

Professor Chia-Kuang (Frank) Tsung made his scientific impact primarily through the atomic-level design of nanoscale materials for application in heterogeneous catalysis. He approached this challenge from two directions: above and below the material surface. Below the surface, Prof. Tsung synthesized finely controlled nanoparticles, primarily of noble metals and metal oxides, tailoring their composition and surface structure for efficient catalysis. Above the surface, he was among the first to leverage the tunability and stability of metal-organic frameworks (MOFs) to improve heterogeneous, molecular, and biocatalysts. This article, written by his former students, seeks first to commemorate Prof. Tsung's scientific accomplishments in three parts: (1) rationally designing nanocrystal surfaces to promote catalytic activity; (2) encapsulating nanocrystals in MOFs to improve catalyst selectivity; and (3) tuning the host-guest interaction between MOFs and guest molecules to inhibit catalyst degradation. The subsequent discussion focuses on building on the foundation laid by Prof. Tsung and on his considerable influence on his former group members and collaborators, both inside and outside of the lab.

Heterogenizing a Homogeneous Nickel Catalyst Using Nanoconfined Strategy for Selective Synthesis of Mono- and 1,2-Disubstituted Benzimidazoles

A homogeneous Ni-phenanthroline catalyst was successfully immobilized into the cavities of a metal-organic framework, ZIF-8. The as-synthesized heterogeneous catalyst, Ni-Phen@ZIF, represents the first MOF based catalyst that enables dehydrogenative coupling of alcohols with aromatic diamines for selective synthesis of both mono- and 1,2-disubstituted benzimidazoles. The catalyst survived under harsh basic conditions, characterized by SEM, TEM, BET, PXRD, and EDX elemental mappings. The presence of the nanoconfined Ni-phenanthroline complex and the formation of extra Lewis acid sites during catalysis in the Ni-Phen@ZIF structure, confirmed by TPD analysis and kinetic experiments, might be responsible for higher activity and selectivity.

Heterogenisation of polyoxometalates and other metal-based complexes in metal–organic frameworks: from synthesis to characterisation and applications in catalysis

This review provides a thorough overview of composites with molecular catalysts (polyoxometalates, or organometallic or coordination complexes) immobilised into MOFs via non-covalent interactions.

Incorporation of homogeneous organometallic catalysts into metal–organic frameworks for advanced heterogenization: a review

The heterogenization of homogeneous organometallic catalysts by incorporation into MOFs using different strategies, MOF selection, OMC selection, and the use of hybrid heterogeneous catalysts OMC@MOFs in catalytic applications are summarized and discussed.

The role of metal–organic porous frameworks in dual catalysis

Metal–organic frameworks (MOFs) are a valuable group of porous crystalline solids with inorganic and organic parts that can be used in dual catalysis.

Controlled syntheses of Ag nanoparticles inside MOFs by using amine-borans as vapour phase reductants

Controlled synthesis of Ag nanoparticles inside porous materials is difficult because of their high mobilities during the reactions. Herein, by using a series of amine-boranes as vapour phase reductants, we succeeded in synthesizing Ag nanoparticles in a controlled manner inside MOFs.

Photophysical Properties and Heterogeneous Photoredox Catalytic Activities of Ru(bpy)3 @InBTB Metal-Organic Framework (MOF)

Metal-organic frameworks (MOFs) with negatively charged frameworks are suitable for selectively encapsulating cationic guest ions via a cation-exchange process. Encapsulating photoactive [RuL₃ ]²⁺ polypyridine complexes into the preorganized mesoscale channels of a MOF is a good method for stabilizing the excited states of the complexes. Three new RuL₃ @InBTB MOFs were prepared by encapsulating cationic [Ru(bpy)₃ ]²⁺ (bpy=2,2'-bipyridine), [Ru(phen)₃ ]²⁺ (phen=1,10-phenanthroline), and [Ru(bpz)₃ ]²⁺ (bpz=2,2'-bipyrazine) into the mesopores of a three-dimensional (3D) InBTB MOF (H₃ BTB=1,3,5-benzenetribenzoic acid). The photophysical properties of the resulting materials were investigated by photoluminescence (PL) analysis. The photoredox catalytic activities were also investigated for the aza-Henry reaction, hydrogenation of dimethyl maleate, and decomposition of methyl orange under visible light irradiation at room temperature. RuL₃ @InBTB MOFs were found to be very stable and highly recyclable photoredox catalytic systems.

Metal-Organic Frameworks and Metal-Organic Cages - A Perspective

The fields of metal-organic cages (MOCs) and metal-organic frameworks (MOFs) are both highly topical and continue to develop at a rapid pace. Despite clear synergies between the two fields, overlap is rarely observed. This article discusses the peculiarities and similarities of MOCs and MOFs in terms of synthetic strategies and approaches to system characterisation. The stability of both classes of material is compared, particularly in relation to their applications in guest storage and catalysis. Lastly, suggestions are made for opportunities for each field to learn and develop in partnership with the other.

Metal-Organic Framework-Based Catalysts with Single Metal Sites

Metal-organic frameworks (MOFs) are a class of distinctive porous crystalline materials constructed by metal ions/clusters and organic linkers. Owing to their structural diversity, functional adjustability, and high surface area, different types of MOF-based single metal sites are well exploited, including coordinately unsaturated metal sites from metal nodes and metallolinkers, as well as active metal species immobilized to MOFs. Furthermore, controllable thermal transformation of MOFs can upgrade them to nanomaterials functionalized with active single-atom catalysts (SACs). These unique features of MOFs and their derivatives enable them to serve as a highly versatile platform for catalysis, which has actually been becoming a rapidly developing interdisciplinary research area. In this review, we overview the recent developments of catalysis at single metal sites in MOF-based materials with emphasis on their structures and applications for thermocatalysis, electrocatalysis, and photocatalysis. We also compare the results and summarize the major insights gained from the works in this review, providing the challenges and prospects in this emerging field.

Exploiting π-π Interactions to Design an Efficient Sorbent for Atrazine Removal from Water

The United States Environmental Protection Agency (EPA) recognizes atrazine, a commonly used herbicide, as an endocrine disrupting compound. Excessive use of this agrochemical results in contamination of surface and ground water supplies via agricultural runoff. Efficient removal of atrazine from contaminated water supplies is paramount. Here, the mechanism governing atrazine adsorption in Zr₆-based metal-organic frameworks (MOFs) has been thoroughly investigated by studying the effects of MOF linkers and topology on atrazine uptake capacity and uptake kinetics. We found that the mesopores of NU-1000 facilitated rapid atrazine uptake saturating in <5 min and that the pyrene-based linkers offered sufficient sites for π-π interactions with atrazine as demonstrated by the near 100% uptake. Without the presence of a pyrene-based linker, NU-1008, a MOF similar to NU-1000 with respect to surface area and pore size, removed <20% of the exposed atrazine. These results suggest that the atrazine uptake capacity demonstrated by NU-1000 stems from the presence of a pyrene core in the MOF linker, affirming that π-π stacking is responsible for driving atrazine adsorption. Furthermore, NU-1000 displays an exceptional atrazine removal capacity through three cycles of adsorption-desorption. Powder X-ray diffraction and Brunauer-Emmett-Teller surface area analysis confirmed the retention of MOF crystallinity and porosity throughout the adsorption-desorption cycles.

Photophysical properties of cationic dyes captured in the mesoscale channels of micron-sized metal-organic framework crystals

The optical properties of dye molecules in confined spaces can differ from the solution phase due to confinement effects. Pre-organized mesoscale channels of metal-organic frameworks (MOFs) are very suited for hosting various dyes, and the robust frameworks often render the encapsulated dyes with certain preferential geometries, which are different from those found in solution. Furthermore, pre-organized open channels can efficiently guide the uniform and unique spatial distribution of dye molecules in a controlled manner, which are otherwise difficult to achieve. Thus, sufficiently large dye molecules can avoid the formation of complex aggregates when captured inside open channels. In contrast, small dye molecules can form well-defined dimers or aggregates. The resulting dye-encapsulated MOFs can display unusual photophysical properties of the captured dyes. An anionic framework of In-BTB with mesoscale 3D channels is utilized for the efficient encapsulation of various cationic dyes through cation-exchange processes. Six different cationic dyes are encapsulated in the anionic framework of In-BTB, and their crystal structures are completely solved. Novel photophysical properties of these spatially distributed dye molecules in dye@In-BTBs are investigated.

Rational Design of Catalytic Centers in Crystalline Frameworks

Crystalline frameworks including primarily metal organic frameworks (MOF) and covalent organic frameworks (COF) have received much attention in the field of heterogeneous catalysts recently. Beyond providing large surface area and spatial confinement, these crystalline frameworks can be designed to either directly act as or influence the catalytic sites at molecular level. This approach offers a unique advantage to gain deeper insights of structure-activity correlations in solid materials, leading to new guiding principles for rational design of advanced solid catalysts for potential important applications related to energy and fine chemical synthesis. In this review, recent key progress achieved in designing MOF- and COF-based molecular solid catalysts and the mechanistic understanding of the catalytic centers and associated reaction pathways are summarized. The state-of-the-art rational design of MOF- and COF-based solid catalysts in this review is grouped into seven different areas: (i) metalated linkers, (ii) metalated moieties anchored on linkers, (iii) organic moieties anchored on linkers, (iv) encapsulated single sites in pores, and (v) metal-mode-based active sites in MOFs. Along with this, some attention is paid to theoretical studies about the reaction mechanisms. Finally, technical challenges and possible solutions in applying these catalysts for practical applications are also presented.

Aerosol-Assisted Rapid Fabrication of a Heterogeneous Organopalladium Catalyst with Hierarchical Bimodal Pores

Heterogeneous organometallic catalysts with well-defined active sites and hierarchical pores hold tremendous promise for efficient and eco-friendly chemical processes. However, the simple and scalable preparation of these materials remains difficult to date, which has hampered a more broad application scope. Herein, we reported a low-cost, rapid, and scalable aerosol-assisted assembly approach for the synthesis of a well-defined PdDPP (PdCl₂(PPh₂(CH₂)₂))_ complex-containing benzene-bridged organosilica-based catalyst with a hierarchical bimodal micro-macroporous structure. This novel material was realized by using Pd(II) organometallic silane (Pd[PPh₂(CH₂)₂Si(OEt)₃]₂Cl₂) as the active species, organosilane 1,4-bis(triethoxysilyl)benzene (Ph[Si(OEt)₃]₂) as the silicate scaffold and the surfactant cetyltrimethylammonium bromide and the inorganic salt NaCl as the dual templates on a home-built aerosol spraying-instrument. Multiple techniques including X-ray photoelectron spectroscopy and solid-state NMR spectra revealed that the organopalladium complex with a well-defined molecular configuration of major trans model and minor cis model existed in the phenyl-functionalized silica material. As expected, it efficiently promoted a variety of important carbon-carbon cross-coupling transformations including Tsuji-Trost, Sonogashira, and Suzuki reactions in pure water without the assistance of any additives. In comparison with the homogeneous catalyst PdCl₂(PPh₂CH₃)₂, it even exhibited enhanced activity and selectivity in some cases owing to the unique confinement effect and the shape selectivity generated from the hierarchical porous structure. Meanwhile, it was easily recycled and reused eight times without the loss of its activity.

Encapsulation of Crabtree's Catalyst in Sulfonated MIL-101(Cr): Enhancement of Stability and Selectivity between Competing Reaction Pathways by the MOF Chemical Microenvironment

Crabtree's catalyst was encapsulated inside the pores of the sulfonated MIL-101(Cr) metal-organic framework (MOF) by cation exchange. This hybrid catalyst is active for the heterogeneous hydrogenation of non-functionalized alkenes either in solution or in the gas phase. Moreover, encapsulation inside a well-defined hydrophilic microenvironment enhances catalyst stability and selectivity to hydrogenation over isomerization for substrates bearing ligating functionalities. Accordingly, the encapsulated catalyst significantly outperforms its homogeneous counterpart in the hydrogenation of olefinic alcohols in terms of overall conversion and selectivity, with the chemical microenvironment of the MOF host favouring one out of two competing reaction pathways.

Magnetic functionalities in MOFs: from the framework to the pore

In this review, we show the different approaches developed so far to prepare metal-organic frameworks (MOFs) presenting electronic functionalities, with particular attention to magnetic properties. We will cover the chemical design of frameworks necessary for the incorporation of different magnetic phenomena, as well as the encapsulation of functional species in their pores leading to hybrid multifunctional MOFs combining an extended lattice with a molecular lattice.

Solid-state molecular organometallic chemistry. Single-crystal to single-crystal reactivity and catalysis with light hydrocarbon substrates

Solid-state molecular organometallic catalysis (SMOM-cat): synthetic routes, unique structural motifs, mobility in the solid-state and very active gas/solid isomerization catalysts.

Single-crystal to single-crystal solid/gas reactivity and catalysis starting from the precursor sigma-alkane complex [Rh(Cy₂PCH₂CH₂PCy₂)(η²η²-NBA)][BAr^F₄] (NBA = norbornane; Ar^F = 3,5-(CF₃)₂C₆H₃) is reported. By adding ethene, propene and 1-butene to this precursor in solid/gas reactions the resulting alkene complexes [Rh(Cy₂PCH₂CH₂PCy₂)(alkene)_x][BAr^F₄] are formed. The ethene (x = 2) complex, [Rh(Cy₂PCH₂CH₂PCy₂)(ethene)₂][BAr^F₄]-Oct, has been characterized in the solid-state (single-crystal X-ray diffraction) and by solution and solid-state NMR spectroscopy. Rapid, low temperature recrystallization using solution methods results in a different crystalline modification, [Rh(Cy₂PCH₂CH₂PCy₂)(ethene)₂][BAr^F₄]-Hex, that has a hexagonal microporous structure (P6₃22). The propene complex (x = 1) [Rh(Cy₂PCH₂CH₂PCy₂)(propene)][BAr^F₄] is characterized as having a π-bound alkene with a supporting γ-agostic Rh···H₃C interaction at low temperature by single-crystal X-ray diffraction, variable temperature solution and solid-state NMR spectroscopy, as well as periodic density functional theory (DFT) calculations. A fluxional process occurs in both the solid-state and solution that is proposed to proceed via a tautomeric allyl-hydride. Gas/solid catalytic isomerization of d₃-propene, H₂C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> CHCD₃, using [Rh(Cy₂PCH₂CH₂PCy₂)(η²η²-NBA)][BAr^F₄] scrambles the D-label into all possible positions of the propene, as shown by isotopic perturbation of equilibrium measurements for the agostic interaction. Periodic DFT calculations show a low barrier to H/D exchange (10.9 kcal mol^–1, PBE-D3 level), and GIPAW chemical shift calculations guide the assignment of the experimental data. When synthesized using solution routes a bis-propene complex, [Rh(Cy₂PCH₂CH₂PCy₂)(propene)₂][BAr^F₄], is formed. [Rh(Cy₂PCH₂CH₂PCy₂)(butene)][BAr^F₄] (x = 1) is characterized as having 2-butene bound as the cis-isomer and a single Rh···H₃C agostic interaction. In the solid-state two low-energy fluxional processes are proposed. The first is a simple libration of the 2-butene that exchanges the agostic interaction, and the second is a butene isomerization process that proceeds via an allyl-hydride intermediate with a low computed barrier of 14.5 kcal mol^–1. [Rh(Cy₂PCH₂CH₂PCy₂)(η²η²-NBA)][BAr^F₄] and the polymorphs of [Rh(Cy₂PCH₂CH₂PCy₂)(ethene)₂][BAr^F₄] are shown to be effective in solid-state molecular organometallic catalysis (SMOM-Cat) for the isomerization of 1-butene to a mixture of cis- and trans-2-butene at 298 K and 1 atm, and studies suggest that catalysis is likely dominated by surface-active species. [Rh(Cy₂PCH₂CH₂PCy₂)(η²η²-NBA)][BAr^F₄] is also shown to catalyze the transfer dehydrogenation of butane to 2-butene at 298 K using ethene as the sacrificial acceptor.

Rendering High Surface Area, Mesoporous Metal-Organic Frameworks Electronically Conductive

We report the design and synthesis of a metal-organic framework (MOF)-polythiophene composite that has comparable electronic conductivity to reported conductive 3-D MOFs, but with display and retention of high porosity, including mesoporosity. A robust zirconium MOF, NU-1000, was rendered electronically conductive by first incorporating, via solvent-assisted ligand incorporation (SALI), a carefully designed pentathiophene derivative at a density of one pentamer per hexa-zirconium node. Using a cast film of the intermediate composite (termed pentaSALI) on conductive glass, the incorporated oligothiophene was electrochemically polymerized to yield the conductive composite, Epoly. Depending on the doping level of the polythiophene in the composite, it can be tuned from an insulating state to a semiconduting state with conductivity of 1.3 × 10^-7 (S cm^-1), which is comparable to values reported for 3-D conductive MOFs. The porosity of the thin-film MOF-polythiophene composite was assessed using decane vapor uptake as determined by quartz crystal microgravimetry (QCM). The results indicate a porosity (pore volume) for Epoly essentially identical to that of bulk pentaSALI, and ∼74% of that of unmodified NU-1000. PentaSALI, and by inference Epoly, displays both micro- and mesoporosity, and features a BET surface area of nearly 1,600 m²·g^-1, i.e., substantially larger than yet reported for any other electronically conductive MOF.

Single-Crystal-to-Single-Crystal Anion Exchange in a Gadolinium MOF: Incorporation of POMs and [AuCl₄]. Polymers (Basel) 2016;8:E171. [PMID: 30979261 PMCID: PMC6431858 DOI: 10.3390/polym8050171]

The encapsulation of functional molecules inside porous coordination polymers (also known as metal-organic frameworks, MOFs) has become of great interest in recent years at the field of multifunctional materials. In this article, we present a study of the effects of size and charge in the anion exchange process of a Gd based MOF, involving molecular species like polyoxometalates (POMs), and [AuCl₄]-. This post-synthetic modification has been characterized by IR, EDAX, and single crystal diffraction, which have provided unequivocal evidence of the location of the anion molecules in the framework.

Hydrogen bond-directed encapsulation of metalloporphyrin into the microcages of zeolite imidazolate frameworks for synergistic biomimetic catalysis

In efforts to replicate the 3D model and desirable function of haemoglobin, the zeolite imidazolate framework (ZIF-8) was delineated for an ideal host matrix to accommodate custom-designed porphyrin molecules via hydrogen bonding.