Gas reactions under intrapore condensation regime within tailored metal-organic framework catalysts

Bimetallic Metal Sites in Metal-Organic Frameworks Facilitate the Production of 1-Butene from Electrosynthesized Ethylene

Converting CO2 to synthetic hydrocarbon fuels is of increasing interest. In light of progress in electrified CO2 to ethylene, we explored routes to dimerize to 1-butene, an olefin that can serve as a building block to ethylene longer-chain alkanes. With goal of selective and active dimerization, we investigate a series of metal-organic frameworks having bimetallic catalytic sites. We find that the tunable pore structure enables optimization of selectivity and that periodic pore channels enhance activity. In a tandem system for the conversion of CO2 to 1-C4H8, wherein the outlet cathodic gas from a CO2-to-C2H4 electrolyzer is fed directly (via a dehumidification stage) into the C2H4 dimerizer, we study the highest-performing MOF found herein: M' = Ru and M″ = Ni in the bimetallic two-dimensional M'2(OAc)4M″(CN)4 MOF. We report a 1-C4H8 production rate of 1.3 mol gcat-1 h-1 and a C2H4 conversion of 97%. From these experimental data, we project an estimated cradle-to-gate carbon intensity of -2.1 kg-CO2e/kg-1-C4H8 when CO2 is supplied from direct air capture and when the required energy is supplied by electricity having the carbon intensity of wind.

Computational design of metal hydrides on a defective metal-organic framework HKUST-1 for ethylene dimerization

Catalytic ethylene dimerization to 1-butene is a crucial reaction in the chemical industry, as 1-butene is used for the production of most common plastics (e.g., polyethylene). With well-defined tuneable structures and unsaturated active sites, defective metal-organic frameworks have recently emerged as potential catalysts for ethylene dimerization. Herein, we computationally design a series of metal hydrides on defective HKUST-1 namely H-M-DHKUST-1 (M: Co, Ni, Cu, Ru, Rh and Pd), and subsequently assess their catalytic activity for ethylene dimerization by density functional theory calculations. Due to the antiferromagnetic behavior of dimeric metal-based clusters, we comprehensively investigate all possible multiplicity states on H-M-DHKUST-1 and observe multiplicity crossing. The ground-state reaction barriers for four elementary steps (initiation, C-C coupling, β-hydride elimination and 1-butene desorption) are rationalized and C-C coupling is revealed to be the rate-determining step on H-Co-, H-Ni-, H-Ru-, H-Rh- and H-Pd-DHKUST-1. The energy barrier for β-hydride elimination is found to be the lowest on H-Ru- and H-Rh-DHKUST-1, attributed to the weak stability of agostic arrangement; however, the energy barrier for 1-butene desorption is the highest on H-Rh-DHKUST-1. Among the designed H-M-DHKUST-1, Co- and Ni-based ones are predicted to exhibit the best overall catalytic performance. The mechanistic insights from this study may facilitate the development of new MOFs toward efficient ethylene dimerization and other industrially important reactions.

Confinement effect of ionic liquid: Improve of the extraction performance of parent metal organic framework for phthalates

In order to better identify the hazards of pollutants, developing the analytical methods that can sensitively detect and precisely monitor the content of trace pollutants has been the constant pursuit. In this paper, a new solid phase microextraction coating-ionic liquid/metal organic framework (IL/MOF) was obtained through the IL-induced strategy and used for the solid phase microextraction (SPME) process. IL was introduced into metal-organic framework (MOF) cage based on the anion of ionic liquid could interact strongly with the zirconium nodes of UiO-66-NH₂. The introduction of IL not only increased the stability of composite, the hydrophobicity of IL also changed the environment of MOF channel, providing the hydrophobic effect to the targets. The confinement effect of IL effectively improved the extraction performance of parent MOF and the extraction performance of synthesized IL/UiO-66-NH₂ for phthalates (PAEs) were 1.3-3.0 times that of parent UiO-66-NH₂. Thanks to the strong interaction force (hydrogen bonding interaction, π-π stacking, hydrophobic interaction force), the IL/UiO-66-NH₂-coated fiber coupled with gas chromatography-mass spectrometer showed a wide linear ranges (1-5000 ng L^-1) with good correlation (R², 0.9855-0.9987), lower detection limit (0.2-0.4 ng L^-1) and satisfactory recoveries (95.3-119.3%) for PAEs. This article is dedicated to provide another way to improve the extraction performance of material.

Conceptual and Practical Aspects of Metal-Organic Frameworks for Solid-Gas Reactions

The presence of site-isolated and well-defined metal sites has enabled the use of metal-organic frameworks (MOFs) as catalysts that can be rationally modulated. Because MOFs can be addressed and manipulated through molecular synthetic pathways, they are chemically similar to molecular catalysts. They are, nevertheless, solid-state materials and therefore can be thought of as privileged solid molecular catalysts that excel in applications involving gas-phase reactions. This contrasts with homogeneous catalysts, which are overwhelmingly used in the solution phase. Herein, we review theories dictating gas phase reactivity within porous solids and discuss key catalytic gas-solid reactions. We further treat theoretical aspects of diffusion within confined pores, the enrichment of adsorbates, the types of solvation spheres that a MOF might impart on adsorbates, definitions of acidity/basicity in the absence of solvent, the stabilization of reactive intermediates, and the generation and characterization of defect sites. The key catalytic reactions we discuss broadly include reductive reactions (olefin hydrogenation, semihydrogenation, and selective catalytic reduction), oxidative reactions (oxygenation of hydrocarbons, oxidative dehydrogenation, and carbon monoxide oxidation), and C-C bond forming reactions (olefin dimerization/polymerization, isomerization, and carbonylation reactions).

Defects engineering simultaneously enhances activity and recyclability of MOFs in selective hydrogenation of biomass

The development of synthetic methodologies towards enhanced performance in biomass conversion is desirable due to the growing energy demand. Here we design two types of Ru impregnated MIL-100-Cr defect engineered metal-organic frameworks (Ru@DEMOFs) by incorporating defective ligands (DLs), aiming at highly efficient catalysts for biomass hydrogenation. Our results show that Ru@DEMOFs simultaneously exhibit boosted recyclability, selectivity and activity with the turnover frequency being about 10 times higher than the reported values of polymer supported Ru towards D-glucose hydrogenation. This work provides in-depth insights into (i) the evolution of various defects in the cationic framework upon DLs incorporation and Ru impregnation, (ii) the special effect of each type of defects on the electron density of Ru nanoparticles and activation of reactants, and (iii) the respective role of defects, confined Ru particles and metal single active sites in the catalytic performance of Ru@DEMOFs for D-glucose selective hydrogenation as well as their synergistic catalytic mechanism.

The catalytic performance of metal‒organic frameworks can be tuned by introducing defects in their structure. Here, the authors introduce defects and impregnate ruthenium nanoparticles in cationic metal-organic frameworks, which enables enhanced recyclability and catalytic performance in D-glucose hydrogenation.

Ethylene polymerization with a crystallographically well-defined metal–organic framework supported catalyst

Crystallographic characterization of a heterogeneous ethylene polymerization catalyst elucidates a chromium–carbon bond after alkyl aluminum activation and provides mechanistic insights.

High-Performance Lithium-Ion Capacitors Based on Porosity-Regulated Zirconium Metal-Organic Frameworks

Comprised of a battery anode and a supercapacitor cathode, hybrid lithium-ion capacitors (HLICs) are found to be an effective solution to realize both high power density and high energy density at the same time. Organic-inorganic hybrid materials with well-organized framework guided by the reticular chemistry are one of the promising anode materials for HLICs because of rich active sites and ordered porosity. Herein, metal-organic framework consisting of Zr⁴⁺ metal ions and tetrathiafulvalene-based ligands (Zr-MOF) is proposed as the pseudocapacitive anode of HLICs. The Zr-MOF possesses high stability, high crystallinity, and multiple meso-microporous channels favorable for ion transport. The as-prepared Zr-MOF||activated carbon HLICs present high energy density (122.5 Wh kg^-1 ), high power density (12.5 kW kg^-1 ), and stable cycling performance (86% capacity retention after 1000 cycles at 2000 mA g^-1 ) within the operating voltage range of 1.0-4.0 V. The results expand the direct application of MOF for bridging the performance gap between batteries and supercapacitors.

Highly Active Heterogeneous Catalyst for Ethylene Dimerization Prepared by Selectively Doping Ni on the Surface of a Zeolitic Imidazolate Framework

The production of 1-butene by ethylene dimerization is an important chemical industrial process currently implemented using homogeneous catalysts. Here, we describe a highly active heterogeneous catalyst (Ni-ZIF-8) for ethylene dimerization, which consists of isolating Ni-active sites selectively located on the crystal surface of a zeolitic imidazolate framework. Ni-ZIF-8 can be easily prepared by a simple one-pot synthesis method in which site-specific anchoring of Ni is achieved spontaneously because of the incompatibility between the d⁸ electronic configuration of Ni²⁺ and the three-dimensional framework of ZIF-8. The full exposure and square-planar coordination of the Ni sites accounts for the high catalytic activity of Ni-ZIF-8. It exhibits an average ethylene turnover frequency greater than 1 000 000 h^-1 (1-butene selectivity >85%) at 35 °C and 50 bar, far exceeding the activities of previously reported heterogeneous catalysts and many homogeneous catalysts under similar conditions. Moreover, compared to molecular Ni complexes used as homogeneous catalysts for ethylene dimerization, Ni-ZIF-8 has significantly higher stability and shows constant activity during 4 h of continuous reaction. Isotopic labeling experiments indicate that ethylene dimerization over Ni-ZIF-8 follows the Cossee-Arlman mechanism, and detailed characterizations combined with density functional theory calculations rationalize this observed high activity.

Scrutinizing ligand exchange reactions in the formation of the precious group metal-organic framework RuII,II-HKUST-1: the impact of diruthenium tetracarboxylate precursor and modulator choice

The precious group metal (PGM) analogues of the iconic metal-organic framework [Cu3(BTC)2] (HKUST-1; BTC = 1,3,5 benzenetricarboxylate) still represent a synthetic challenge, especially if targeting the univalent and ideally defect-free RuII,II variant. Herein we present a systematic study employing the controlled secondary building unit approach (CSA) by using a variety of diruthenium tetracarboxylate complexes [Ru2(RCO2)4] as precursors in the synthesis of univalent Ru-HKUST-1 samples. Carboxylate ligand exchange test reactions suggest the importance of a pKa match between precursor ligand and BTC linker. For example, l-mandelate substituted precursors resulted in the most "perfect" samples of the investigated series with a fourfold increase in crystalline domain sizes compared to the established acetate route (according to PXRD and HR-TEM), high compositional purity (FT-IR, Raman, TGA and elemental analysis) and feature a so far unprecedentedly high BET surface area of 1789 m2 g-1 with the expected pore size distribution and total pore volume all similar to the ideal HKUST-1 parent structure.

Kinetic effects of molecular clustering and solvation by extended networks in zeolite acid catalysis

Reactions catalyzed within porous inorganic and organic materials and at electrochemical interfaces commonly occur at high coverage and in condensed media, causing turnover rates to depend strongly on interfacial structure and composition, collectively referred to as "solvent effects". Transition state theory treatments define how solvation phenomena enter kinetic rate expressions, and identify two distinct types of solvent effects that originate from molecular clustering and from the solvation of such clusters by extended solvent networks. We review examples from the recent literature that investigate reactions within microporous zeolite catalysts to illustrate these concepts, and provide a critical appraisal of open questions in the field where future research can aid in developing new chemistry and catalyst design principles.

Defects as catalytic sites for the oxygen evolution reaction in Earth-abundant MOF-74 revealed by DFT

The oxygen evolution reaction (OER) is the bottleneck of hydrogen production via water splitting and understanding electrocatalysts at atomic level becomes paramount to enhance the efficiency of this process.

Snowflake porous multi-metal oxide nanocatalysts from metallocene@metal organic framework precursors

Snowflake metallocene@MOF-derived ammonia catalyst.

Thermal Defect Engineering of Precious Group Metal-Organic Frameworks: A Case Study on Ru/Rh-HKUST-1 Analogues

A methodology is introduced for controlled postsynthetic thermal defect engineering (TDE) of precious group metal-organic frameworks (PGM-MOFs). The case study is based on the Ru/Rh analogues of the archetypical structure [Cu₃(BTC)₂] (HKUST-1; BTC = 1,3,5-benzenetricarboxylate). Quantitative monitoring of the TDE process and extensive characterization of the samples employing a complementary set of analytical and spectroscopic techniques reveal that the compositionally very complex TDE-MOF materials result from the elimination and/or fragmentation of ancillary ligands and/or linkers. TDE involves the preferential secession of acetate ligands, intrinsically introduced via coordination modulation during synthesis, and the gradual decarboxylation of ligator sites of the framework linker BTC. Both processes lead to modified Ru/Rh paddlewheel nodes. These nodes exhibit a lowered average oxidation state and more accessible open metal centers, as deduced from surface-ligand IR spectroscopy using CO as a probe and supported by density functional theory (DFT)-based computations. The monometallic and the mixed-metal PGM-MOFs systematically differ in their TDE properties and, in particular in the hydride generation ability (HGA). This latter property is an important indicator for the catalytic activity of PGM-MOFs, as demonstrated by the ethylene dimerization reaction to 1-butene.

Air-thermal processing of hierarchically porous metal-organic frameworks

Metal-organic frameworks (MOFs) show great potential for various applications. The functions of MOFs are closely related to their porous structures and lattice integrities. However, the generally existing guest solvent/linker molecules and crystalline defects will alter internal microstructures and microenvironments of MOFs. Meanwhile, although MOFs have tailorable pore structures within the range of microspores, the achievement of meso/macropores in MOFs is of scientific interest. Herein, a versatile air-thermal processing (ATP) strategy is reported to remove the residual molecules and incompletely coordinated linkers in MOFs. Through processing MOFs in confined space, the thermalized and pressurized air can assist the filling solvents and partially/totally uncoordinated linkers to overcome the energy barrier of escape, and then maximize MOF porosity. The obtained MOF materials with hierarchical micro/mesoporous structures display substantially improved adsorption capacities and selectivities. For example, CuBTC-A shows 36%, 72%, 22%, and 86% enhancements in surface area, pore volume, CO₂ uptake, and CO₂/N₂ selectivity, respectively. Moreover, by adjusting processing temperature, the ATP strategy is available for fabricating MOF materials with hierarchically micro/meso/macroporous superstructures under modulator/template-free conditions.

Structure and solvation of confined water and water-ethanol clusters within microporous Brønsted acids and their effects on ethanol dehydration catalysis

Water networks confined within zeolites solvate clustered reactive intermediates and must rearrange to accommodate transition states that differ in size and polarity, with thermodynamic penalties that depend on the shape of the confining environment.

Aqueous-phase reactions within microporous Brønsted acids occur at active centers comprised of water-reactant-clustered hydronium ions, solvated within extended hydrogen-bonded water networks that tend to stabilize reactive intermediates and transition states differently. The effects of these diverse clustered and networked structures were disentangled here by measuring turnover rates of gas-phase ethanol dehydration to diethyl ether (DEE) on H-form zeolites as water pressure was increased to the point of intrapore condensation, causing protons to become solvated in larger clusters that subsequently become solvated by extended hydrogen-bonded water networks, according to in situ IR spectra. Measured first-order rate constants in ethanol quantify the stability of S_N2 transition states that eliminate DEE relative to (C₂H₅OH)(H⁺)(H₂O)_n clusters of increasing molecularity, whose structures were respectively determined using metadynamics and ab initio molecular dynamics simulations. At low water pressures (2–10 kPa H₂O), rate inhibition by water (–1 reaction order) reflects the need to displace one water by ethanol in the cluster en route to the DEE-formation transition state, which resides at the periphery of water–ethanol clusters. At higher water pressures (10–75 kPa H₂O), water–ethanol clusters reach their maximum stable size ((C₂H₅OH)(H⁺)(H₂O)_4–5), and water begins to form extended hydrogen-bonded networks; concomitantly, rate inhibition by water (up to –3 reaction order) becomes stronger than expected from the molecularity of the reaction, reflecting the more extensive disruption of hydrogen bonds at DEE-formation transition states that contain an additional solvated non-polar ethyl group compared to the relevant reactant cluster, as described by non-ideal thermodynamic formalisms of reaction rates. Microporous voids of different hydrophilic binding site density (Beta; varying H⁺ and Si–OH density) and different size and shape (Beta, MFI, TON, CHA, AEI, FAU), influence the relative extents to which intermediates and transition states disrupt their confined water networks, which manifest as different kinetic orders of inhibition at high water pressures. The confinement of water within sub-nanometer spaces influences the structures and dynamics of the complexes and extended networks formed, and in turn their ability to accommodate the evolution in polarity and hydrogen-bonding capacity as reactive intermediates become transition states in Brønsted acid-catalyzed reactions.

Polypyrrole decorated metal-organic frameworks for supercapacitor devices

Due to their large specific surface areas and porosity, metal-organic frameworks (MOFs) have found many applications in catalysis, gas separation, and gas storage. However, their use as electronic components such as supercapacitors is stunted due to their poor electrical conductivity. We report a remedy for this by combining the MOF structure with polypyrrole (PPy), a well-known conductive polymer. Three MOFs are studied for modification to this end: CPO-27-Ni and CPO-27-Co (M2DOBDC, M = Ni2+, Co2+, DOBDC = 2,5-dihydroxy-1,4-benzenedicarboxylate) and HKUST-1 (Cu3(BTC)2, BTC = 1,3,5 benzenetricarboxylate). The gravimetric capacitance of pure MOFs is boosted several orders of magnitude after reinforcement of PPy (e.g., from 0.679 to 185 F g-1 for HKUST-1 and PPy-HKUST-1, respectively), and is much higher than reported for pure PPy. In total, these PPy-d-MOFs exhibit specific capacitances up to 354 F g-1, retaining 70% of this value even after 2500 cycles. Among them, the highest capacitance is found for PPy-CPO-27-Ni (354 F g-1), followed by PPy-CPO-27-Co (263 F g-1) and PPy-HKUST-1 (185 F g-1). The maximum operating potential for these electrodes is 0.5 V, which is restricted by the contact of MOF with aqueous electrolyte and with extremely low PPy content. As a solution, higher PPy loading and rational adjustment of particle size and porosity of both MOF and PPy are recommended so that the MOF/electrolyte interface is limited, leading to more robust electrode. The work completed here describes a highly promising approach to tackling the electrically insulating nature of MOFs, paving the way for their use in electrochemical energy storage devices.

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.

Multi-Spectroscopic Interrogation of the Spatial Linker Distribution in Defect-Engineered Metal-Organic Framework Crystals: The [Cu3 (btc)2-x (cydc)x ] Showcase

In the past few years, defect-engineered metal-organic frameworks (DEMOFs) have been studied due to the plethora of textural, catalytic, or magnetic properties that can be enhanced by carefully introducing defect sites into the crystal lattices of MOFs. In this work, the spatial distribution of two different non-defective and defective linkers, namely 1,3,5-benzenetricarboxylate (BTC) and 5-cyano-1,3-benzenedicarboxylate (CYDC), respectively, has been studied in different DEMOF crystals of the HKUST-1 topology. Raman micro-spectroscopy revealed a nonhomogeneous distribution of defect sites within the [Cu3 (btc)2-x (cydc)x ] crystals, with the CYDC linker incorporated into defect-rich or defect-free areas of selected crystals. Additionally, advanced bulk techniques have shed light on the nature of the copper species, which is highly dynamic and directly affects the reactivity of the copper sites, as shown by probe molecule FTIR spectroscopy. Furthermore, electron microscopy revealed the effect of co-crystallizing CYDC and BTC on the crystal size and the formation of mesopores, further corroborated by X-ray scattering analysis. In this way we have demonstrated the necessity of utilizing micro-spectroscopy along with a whole array of bulk spectroscopic techniques to fully describe multicomponent metal-organic frameworks.

Peanut Leaf-Inspired Hybrid Metal-Organic Framework with Humidity-Responsive Wettability: toward Controllable Separation of Diverse Emulsions

Damage to the responsive superwetting material by external stimuli during the responsive process has been a ticklish question in recent years. We overcome this barrier by imitating a peanut leaf and designing a humidity-responsive MIL-100 (Fe)/octadecylamine-coated stainless steel mesh (HR-MOS). Such a material shows superhydrophilicity when ambient humidity is higher than saturated humidity, while it shows superhydrophobicity and high adhesion to water when ambient humidity is lower than saturated humidity. The peanut leaf-like two-level nanostructure of MIL-100 (Fe) is speculated as the principal factor to bring about the binary synergy wettability of the material. Accordingly, the material can realize humidity-controlled separation of at least 12 types of emulsions along with satisfactory durability. The responsive condition of the material is mild and green, which does lower damage to the material and environment. This strategy is the first to realize humidity-responsive wettability transition and provides a novel approach for manually controlled environmental protection.

Spectroscopy, microscopy, diffraction and scattering of archetypal MOFs: formation, metal sites in catalysis and thin films

A comprehensive overview of characterization tools for the analysis of well-known metal–organic frameworks and physico-chemical phenomena associated to their applications.

MOF-derived nanostructured catalysts for low-temperature ammonia synthesis

Nanostructured catalysts for low-temperature ammonia synthesis have been developed via thermal treatment under nitrogen of Ru-containing MOFs.

Elucidating the Structure of the Metal-Organic Framework Ru-HKUST-1

Ru-HKUST-1 (Ru 3 ( btc ) 2 X 1.5 ; btc 3 - = 1 , 3 , 5 -benzenetricarboxylate ; X - = chloride , acetate , trimesate , hydroxide ) has received considerable attention as a result of its structure type, tunability, and the redox-active nature of its constituent metal paddlewheel building units. As compared to some of the other members of the HKUST-1 family, its surface area is typically reported as ~25% lower than expected. In contrast to this, a related ruthenium-based porous coordination cage, Ru 24 ( t Bu-bdc ) 24 Cl 12 , displays the expected surface area when compared to Cr 2 + and Mo 2 + analogs. Here, we examine the factors that result in this decreased surface area for the MOF. We show that with appropriate solvent exchange and activation conditions, Ru-HKUST-1 can display a B.E.T. surface areas as high as 1439 m2/g. We utilize a combination of spectroscopic and diffraction techniques to accurately determine the structure of the MOF, which is most accurately described here as Ru 3 ( btc ) 2 ( OAc ) 1.07 Cl 0.43 , as prepared under our conditions. Further, by simply treating the sample as air-sensitive upon isolation, adsorption selectivities toward unsaturated molecu les greatly improve.

ZIF-8 as a Catalyst in Ethylene Oxide and Propylene Oxide Reaction with CO2 to Cyclic Organic Carbonates

CO2 is an important by-product in epoxides synthesis, accounting for 0.02% of worldwide greenhouse emissions. The CO2 cycloaddition to ethylene and propylene oxides is an important class of reactions due to the versatile nature of the corresponding organic carbonates as chemical feedstocks. We report that these reactions can be catalyzed by ZIF-8 (Zeolitic Imidazole Framework-8) in the absence of solvent or co-catalyst and in mild conditions (40 °C and 750 mbar). In situ infrared spectroscopy places the onset time for ethylene and propylene carbonate formation to 80 and 30 min, respectively. Although there is low catalytic activity, these findings suggest the possibility to cut the CO2 emissions from epoxides production through their direct conversion to these highly valuable chemical intermediates, eliminating de facto energetically demanding steps as the CO2 capture and storage.

Eight coordination compounds assembled from unexplored semi-rigid ether-based unsymmetrical tetracarboxylate and various dipyridyl ligands: structural variation, magnetic and photoluminescence properties

Eight new coordination compounds built by an unexplored semi-rigid ether-based unsymmetrical tetracarboxylate and varied dipyridyl ligands have been synthesized. Their variety of structures, photoluminescence and magnetic properties are discussed.

Mixed precious-group metal–organic frameworks: a case study of the HKUST-1 analogue [RuxRh3−x(BTC)2]

Mixed precious-group metal–organic frameworks [Ru_xRh_3−x(BTC)₂] of the HKUST-1-type were synthesized and characterized (PXRD, BET, IR, Raman, XPS, TGA, SS-UV/VIS, EA, and HR-TEM).