Catalysis by Metal Organic Frameworks: Perspective and Suggestions for Future Research

Zn(II)/Cd(II)-Based Metal-Organic Frameworks as Bifunctional Materials for Dye Scavenging and Catalysis of Fructose/Glucose to 5-Hydroxymethylfurfural

Functional neutral metal-organic frameworks (MOFs) {[M(5OH-IP)(L)]}_n [M = Zn(II) for ADES-4; Cd(II) for ADES-5; 5OH-IP = 5-hydroxyisophthalate; L = (E)-N'-(pyridin-3-ylmethylene)nicotinohydrazide) have been synthesized by a diffusion/conventional reflux/mechanochemical method and characterized by various analytical techniques. Crystals were harvested by a diffusion method, and single-crystal X-ray diffraction (SXRD) analysis revealed that an adjacent [M₂(COO)₂]_n ladder chain generates isostructural two-dimensional network motifs by doubly pillaring via L. The bulk-phase purity of ADES-4 and ADES-5 synthesized by a versatile synthetic approach has been recognized by the decent match of powder X-ray diffraction patterns with the simulated one. Both ADES-4 and ADES-5 showed selective adsorption of cationic dyes methylene blue (MB), methyl violet (MV), and rhodamine B (RhB) over anionic dye methyl orange (MO) from water with good uptake and rapid adsorption. Utilization of ADES-4 as a chromatographic column filler for adsorptive removal of individual cationic dyes as well as a mixture of dyes has been demonstrated from the aqueous phase. Interestingly, ADES-4 is reusable with good stability, and it showed a dye desorption phenomenon in methanol. The probable mechanism of cationic dye removal based on insight from structural information and plausible supramolecular interactions has also been explored. Both MOFs also showed efficient catalytic transformation of fructose and glucose into the high-value chemical intermediate 5-hydroxymethylfurfural of industrial significance.

Dimensional Reduction of Lewis Acidic Metal-Organic Frameworks for Multicomponent Reactions

Owing to hindered diffusions, the application of porous catalytic materials has been limited to relatively simple organic transformations with small substrates. Herein we report a dimensional reduction strategy to construct a two-dimensional metal-organic framework (MOF), Zr₆OTf-BTB, with 96% accessible Lewis acidic sites as probed by the bulky Lewis base pivalonitrile. With nearly free substrate accessibility, Zr₆OTf-BTB outperformed two three-dimensional MOF counterparts of similar Lewis acidity (Zr₆OTf-BPDC and Zr₆OTf-BTC) in catalyzing sterically hindered multicomponent reactions (MCRs) for the construction of tetrahydroquinoline and aziridine carboxylate derivatives with high turnover numbers (TONs). Zr₆OTf-BTB was also superior to the homogeneous benchmark Sc(OTf)₃ with nearly 14 times higher TON and 9 times longer catalyst lifetime. Furthermore, the topology-activity relationships in these Zr-based Lewis acidic MOFs were rationalized by comparing their Lewis acidity, numbers of Lewis acidic sites, and sterically accessible Lewis acidic sites. Zr₆OTf-BTB was successfully used to construct several bioactive molecules via MCRs with excellent efficiency. This dimensional reduction strategy should allow the development of other MOF catalysts for synthetically useful and complicated organic transformations.

Calcium-Based Metal-Organic Frameworks and Their Potential Applications

Metal-organic frameworks (MOFs) built on calcium metal (Ca-MOFs) represent a unique subclass of MOFs featuring high stability, low toxicity, and relatively low density. Ca-MOFs show considerable potential for molecular separations, electronic, magnetic, and biomedical applications, although they are not investigated as extensively as transition metal-based MOFs. Compared to MOFs made of other groups of metals, Ca-MOFs may be particularly advantageous for certain applications such as adsorption and storage of light molecules because of their gravimetric benefit, and drug delivery due to their high biocompatibility. This review intends to provide an overview on the recent development of Ca-MOFs, including their synthesis, crystal structures, important properties, and related applications. Various synthetic methods and techniques, types of building blocks, structure and porosity features, selected physical properties, and potential uses will be discussed and summarized. Representative examples will be illustrated for each type of important applications with a focus on their structure-property relations.

Catalytic amplification based on hierarchical heterogeneity bimetal-organic nanostructures with peroxidase-like activity

In this paper, integrating heterometallic units and nanostructures into metal-organic frameworks (MOFs) were applied to improve the sensitivity of detecting hydrogen peroxide (H₂O₂) in neutral solution. The bimetal-MOFs (CuCo-BDC) and GO composite (CuCo-BDC/GO) were first synthesized via an ordinary one-step solvothermal synthesis. The CuCo-BDC/GO with admirable peroxidase-like catalytic activity could be applied to detect H₂O₂. The results have low detection limit of 69 nM (S/N = 3) and a wide linear detection range, from 100 nM to 3.5 mM. This is superior to recently published biosensors based on noble metal nanomaterials, which confirms CuCo-BDC/GO as the MOF electrocatalysts with high performance. The remarkable electroanalytical performance of CuCo-BDC/GO is due to the presence of numerous open metal active sites, the synergistic effect of Cu²⁺ and Co²⁺, hierarchical structure with high-specific surface areas and the marvelous electrochemical properties of GO. Therefore, CuCo-BDC/GO is a powerful candidate for detecting H₂O₂ in electrochemical biosensing fields. Moreover, H₂O₂ detection in real samples can be done with the CuCo-BDC/GO, including human serum samples. Therefore, the novel CuCo-BDC/GO is a promising catalyst that can be applied in biotechnological and environmental applications.

Understanding the Effect of Water on CO2 Adsorption

Carbon capture from large sources and ambient air is one of the most promising strategies to curb the deleterious effect of greenhouse gases. Among different technologies, CO₂ adsorption has drawn widespread attention mostly because of its low energy requirements. Considering that water vapor is a ubiquitous component in air and almost all CO₂-rich industrial gas streams, understanding its impact on CO₂ adsorption is of critical importance. Owing to the large diversity of adsorbents, water plays many different roles from a severe inhibitor of CO₂ adsorption to an excellent promoter. Water may also increase the rate of CO₂ capture or have the opposite effect. In the presence of amine-containing adsorbents, water is even necessary for their long-term stability. The current contribution is a comprehensive review of the effects of water whether in the gas feed or as adsorbent moisture on CO₂ adsorption. For convenience, we discuss the effect of water vapor on CO₂ adsorption over four broadly defined groups of materials separately, namely (i) physical adsorbents, including carbons, zeolites and MOFs, (ii) amine-functionalized adsorbents, and (iii) reactive adsorbents, including metal carbonates and oxides. For each category, the effects of humidity level on CO₂ uptake, selectivity, and adsorption kinetics under different operational conditions are discussed. Whenever possible, findings from different sources are compared, paying particular attention to both similarities and inconsistencies. For completeness, the effect of water on membrane CO₂ separation is also discussed, albeit briefly.

Metal-organic frameworks as catalytic selectivity regulators for organic transformations

Selective organic transformations using metal-organic frameworks (MOFs) and MOF-based heterogeneous catalysts have been an intriguing but challenging research topic in both the chemistry and materials communities. Analogous to the reaction specificity achieved in enzyme pockets, MOFs are also powerful platforms for regulating the catalytic selectivity via engineering their catalytic microenvironments, such as metal node alternation, ligand functionalization, pore decoration, topology variation and others. In this review, we provide a comprehensive introduction and discussion about the role of MOFs played in regulating and even boosting the size-, shape-, chemo-, regio- and more appealing stereo-selectivity in organic transformations. We hope that it will be instructive for researchers in this field to rationally design, conveniently prepare and elaborately functionalize MOFs or MOF-based composites for the synthesis of high value-added organic chemicals with significantly improved selectivity.

Machine learning with persistent homology and chemical word embeddings improves prediction accuracy and interpretability in metal-organic frameworks

Machine learning has emerged as a powerful approach in materials discovery. Its major challenge is selecting features that create interpretable representations of materials, useful across multiple prediction tasks. We introduce an end-to-end machine learning model that automatically generates descriptors that capture a complex representation of a material’s structure and chemistry. This approach builds on computational topology techniques (namely, persistent homology) and word embeddings from natural language processing. It automatically encapsulates geometric and chemical information directly from the material system. We demonstrate our approach on multiple nanoporous metal–organic framework datasets by predicting methane and carbon dioxide adsorption across different conditions. Our results show considerable improvement in both accuracy and transferability across targets compared to models constructed from the commonly-used, manually-curated features, consistently achieving an average 25–30% decrease in root-mean-squared-deviation and an average increase of 40–50% in R² scores. A key advantage of our approach is interpretability: Our model identifies the pores that correlate best to adsorption at different pressures, which contributes to understanding atomic-level structure–property relationships for materials design.

Catalytic Performance of Zr-Based Metal-Organic Frameworks Zr-abtc and MIP-200 in Selective Oxidations with H2 O2

The catalytic performance of Zr-abtc and MIP-200 metal-organic frameworks consisting of 8-connected Zr₆ clusters and tetratopic linkers was investigated in H₂ O₂ -based selective oxidations and compared with that of 12-coordinated UiO-66 and UiO-67. Zr-abtc demonstrated advantages in both substrate conversion and product selectivity for epoxidation of electron-deficient C=C bonds in α,β-unsaturated ketones. The significant predominance of 1,2-epoxide in carvone epoxidation, coupled with high sulfone selectivity in thioether oxidation, points to a nucleophilic oxidation mechanism over Zr-abtc. The superior catalytic performance in the epoxidation of unsaturated ketones correlates with a larger amount of weak basic sites in Zr-abtc. Electrophilic activation of H₂ O₂ can also be realized, as evidenced by the high activity of Zr-abtc in epoxidation of the electron-rich C=C bond in caryophyllene. XRD and FTIR studies confirmed the retention of the Zr-abtc structure after the catalysis. The low activity of MIP-200 in H₂ O₂ -based oxidations is most likely related to its specific hydrophilicity, which disfavors adsorption of organic substrates and H₂ O₂ .

Mechanochemical Synthesis of Nickel-Modified Metal–Organic Frameworks for Reduction Reactions

In this work, we report the incorporation of nickel oxide nanoparticles into a metal–organic framework (MOF) structure by a solvent-free mechanochemical strategy. In particular, the zirconium-based MOF UiO-66 was modified with different Ni loadings and characterized using complementary techniques including X-ray diffraction (XRD), N2 porosimetry and X-ray photoelectron spectroscopy (XPS). The catalytic potential of the as-prepared Ni/UiO-66 materials in the hydrogenation reaction of methyl levulinate using 2-propanol as hydrogen donor solvent has been investigated under flow conditions. Under optimized conditions, the 5%Ni/UiO-66 led to the best catalytic performance (70% yield, 100% selectivity to gamma-valerolactone), which could be attributed to the higher content of the Ni species within the MOF structure. The obtained results are promising and contribute to highlighting the great potential of MOFs in biomass upgrading processes, opening the path to the sustainable development of the chemical industry.

Elucidating and Tuning Catalytic Sites on Zirconium- and Aluminum-Containing Nodes of Stable Metal-Organic Frameworks

ConspectusMetal-organic frameworks (MOFs) are a huge, rapidly growing class of crystalline, porous materials that consist of inorganic nodes linked by organic struts. Offering the advantages of thermal stability combined with high densities of accessible reactive sites, some MOFs are good candidate materials for applications in catalysis and separations. Such MOFs include those with nodes that are metal oxide clusters (e.g., Zr₆O₈, Hf₆O₈, and Zr₁₂O₂₂) and long rods (e.g., [Al(OH)]_n). These nanostructured metal oxides are often compared with bulk metal oxides, but they are in essence different because their structures are not the same and because the MOFs have a high degree of uniformity, offering the prospect of a deep understanding of reactivity that is barely attainable for most bulk metal oxides because of their surface heterogeneity. This prospect is being realized as it has become evident that adventitious components on MOF node surfaces, besides the linkers, are crucial. These ligands arise from modulators, solvents, or products of solvent decomposition in MOF synthesis solutions, and because they are minor components that are often irregularly placed on defects, they may not show up in X-ray diffraction (XRD) crystal structures. Hydroxyl groups on the nodes (like those on bulk metal oxides) are regarded as native functional groups arising from solvent water, but they may barely be present initially, with common ligands instead being formate and acetate formed from modulators formic acid and acetic acid. (Formate also arises from the decomposition of dimethylformamide (DMF) solvent.) Replacement and control of the node ligands is facilitated by postsynthesis reactions (e.g., with alcohols or aqueous HCl/H₂SO₄ solutions) or as a result of high-temperature decomposition. In catalysis, adventitious node ligands can be (a) reaction inhibitors that block active sites on the nodes (e.g., formate blocking Zr, Hf, or Al Lewis acid sites); (b) reaction intermediates (e.g., ethoxy in ethanol dehydration); or (c) active sites themselves (e.g., terminal OH groups in tert-butyl alcohol (TBA) dehydration). Surprisingly, in view of the catalytic importance of such ligands on bulk metal oxides, their subtle chemistry on MOF nodes is only recently being determined. We describe (1) methods for identifying and quantifying node ligands (especially by IR spectroscopy and by ¹H NMR spectroscopy of MOFs digested in NaOH/D₂O solutions); (2) node ligand surface chemistry expressed as reaction networks; (3) catalysis, with mechanisms and energetics determined by density functional theory (DFT) and spectroscopy; and (4) MOF unzipping by reactions of linker carboxylate ligands with reactants such as alcohols that break node-linker bonds, a cause of catalyst deactivation and also an indicator of node-linker bond strength and MOF stability.

Amine-Tagged Fragmented Ligand Installation for Covalent Modification of MOF-74

MOF-74 is one of the most explored metal-organic frameworks (MOFs), but its functionalization is limited to the dative post-synthetic modification (PSM) of the monodentate solvent site. Owing to the nature of the organic ligand and framework structure of MOF-74, the covalent PSM of MOF-74 is very demanding. Herein, we report, for the first time, the covalent PSM of amine-tagged defective Ni-MOF-74, which is prepared by de novo solvothermal synthesis by using aminosalicylic acid as a functionalized fragmented organic ligand. The covalent PSM of the amino group generates metal binding sites, and subsequent post-synthetic metalation with Pd^II ions affords the Pd^II -incorporated Ni-MOF-74 catalyst. This catalyst exhibits highly efficient, size-selective, and recyclable catalytic activity for the Suzuki-Miyaura cross-coupling reaction. This strategy is also useful for the covalent modification of amine-tagged defective Ni₂ (DOBPDC), an expanded analogue of MOF-74.

Prototype Atomically Dispersed Supported Metal Catalysts: Iridium and Platinum

When metal nanoparticles on supports are made smaller and smaller-to the limit of atomic dispersion-they become cationic and take on new catalytic properties that are only recently being discovered. The synthesis of these materials is reviewed, including their structure characterization-especially by atomic-resolution electron microscopy and X-ray absorption and infrared spectroscopies-and relationships between structure and catalyst performance, for reactions including hydrogenations, oxidations, and the water gas shift. Structure determination is challenging because of the intrinsic nonuniformity of the support surfaces-and therefore the structures on them-but fundamental understanding has advanced rapidly, benefiting from nearly uniform catalysts consisting of metals on well-defined-crystalline-supports and their characterization by spectroscopy and microscopy. Recent advances in atomic-resolution electron microscopy have spurred the field, providing stunning images and deep insights into structure. The iridium catalysts have typically been made from organoiridium precursors, opening the way to understanding and control of the metal-support bonding and ligands on the metal, including catalytic reaction intermediates. Platinum catalysts are usually made with less precision, from salt precursors, but they catalyze a wider array of reactions than the iridium, typically being stable at higher temperatures and seemingly offering rich prospect for discovery of new catalysts.

Bifunctional Metal-Organic Layer with Organic Dyes and Iron Centers for Synergistic Photoredox Catalysis

Here we report the design of a bifunctional metal-organic layer (MOL), Hf-EY-Fe, by bridging eosin Y (EY)-capped Hf₆ secondary building units (SBUs) with Fe-TPY (TPY = 4'-(4-carboxyphenyl)[2,2':6',2''-terpyridine]-5,5''-dicarboxylate) ligands. With the organic dye EY as an efficient photosensitizer and TPY-Fe(OTf)₂ as the catalytic center, Hf-EY-Fe efficiently catalyzes aminotrifluoromethylation, hydroxytrifluoromethylation, and chlorotrifluoromethylation of alkenes. Hf-EY-Fe also catalyzes the synthesis of CF₃-substituted derivatives of large bioactive molecules such as rotenone, estrone, and adapalene with sizes of up to 2.2 nm. The proximity between EY and iron centers and their site isolation in Hf-EY-Fe enhance catalytic activity while inhibiting their mutual deactivation, leading to high turnover numbers of up to 1840 and good recyclability of the MOL catalyst.

Ag/AgCl@MIL-88A(Fe) heterojunction ternary composites: towards the photocatalytic degradation of organic pollutants

The efficient utilization of solar energy has received tremendous interest due to the increasing environmental and energy concerns. The present paper discusses the efficient integration of a plasmonic photocatalyst (Ag/AgCl) with an iron-based metal-organic framework (MIL-88A(Fe)) for boosting the visible light photoreactivity of MIL-88A(Fe). Two composites of Ag/AgCl@MIL-88A(Fe), namely MAG-1 and MAG-2 (stoichiometric ratio of Fe to Ag is 5 : 1 and 2 : 1), were successfully synthesized via facile in situ hydrothermal methods followed by UV reduction. The synthesized composite materials are characterized by FTIR, PXRD, UVDRS, PL, FESEM/EDX, TEM and BET analyses. The Ag/AgCl@MIL-88A(Fe) (MAG-2) hybrid system shows excellent photocatalytic activity for the degradation of p-nitrophenol (PNP), rhodamine B (RhB), and methylene blue (MB) under sunlight. We found that 91% degradation of PNP in 80 min, 99% degradation of RhB in 70 min and 94% degradation of MB in 70 min have taken place by using MAG-2 as a catalyst under sunlight. The superior activity of Ag/AgCl@MIL-88A(Fe) (MAG-2) is attributed to the synergistic effects from the surface plasmon resonance (SPR) of Ag NPs and the electron transfer from MIL-88A(Fe) to Ag nanoparticles for effective separation of electron-hole pairs. Furthermore, the mechanism of degradation of PNP, RhB and MB is proposed by analyzing the electron transfer pathway in Ag/AgCl@MIL-88A(Fe).

Microwave-Assisted Air Epoxidation of Mixed Biolefins over a Spherical Bimetal ZnCo-MOF Catalyst

Here, we report the synthesis of spherical bimetal ZnCo-MOF materials by a hydrothermal rotacrystallization method and their catalytic activity on the air epoxidation of mixed biolefins enhanced by microwaves. The structural and chemical properties of the ZnCo-MOF materials were fully characterized by XRD, IR, SEM, TG, XPS, and NH₃-TPD. The morphology of the material exhibited a three-dimensional spherical structure. From an NH₃-TPD test of the ZnCo-MOF catalyst, it could be concluded that the Zn_0.1Co₁-MOF-H-150 rpm material had the highest acidic content and the strongest acidity among the catalysts synthesized by different methods, which gave the best performance in the epoxidation of mixed biolefins. The air epoxidation reaction was carried out under atmospheric pressure and microwave conditions, in the absence of any initiator or coreducing agent. Moreover, the Zn_0.1Co₁-MOF catalyst could be recycled six times without reducing the catalytic activity significantly, which showed the stability of spherical catalyst material under microwaves.

Metal-Organic Frameworks in Oxidation Catalysis with Hydrogen Peroxide

In recent years, metal–organic frameworks (MOFs) have received increasing attention as selective oxidation catalysts and supports for their construction. In this short review paper, we survey recent findings concerning use of MOFs in heterogeneous liquid-phase selective oxidation catalysis with the green oxidant–aqueous hydrogen peroxide. MOFs having outstanding thermal and chemical stability, such as Cr(III)-based MIL-101, Ti(IV)-based MIL-125, Zr(IV)-based UiO-66(67), Zn(II)-based ZIF-8, and some others, will be in the main focus of this work. The effects of the metal nature and MOF structure on catalytic activity and oxidation selectivity are analyzed and the mechanisms of hydrogen peroxide activation are discussed. In some cases, we also make an attempt to analyze relationships between liquid-phase adsorption properties of MOFs and peculiarities of their catalytic performance. Attempts of using MOFs as supports for construction of single-site catalysts through their modification with heterometals will be also addressed in relation to the use of such catalysts for activation of H2O2. Special attention is given to the critical issues of catalyst stability and reusability. The scope and limitations of MOF catalysts in H2O2-based selective oxidation are discussed.

Facile one-pot solvothermal preparation of two-dimensional Ni-based metal-organic framework microsheets as a high-performance supercapacitor material

We report a facile one-pot solvothermal way to prepare two-dimensional Ni-based metal–organic framework microsheets (Ni-MOFms) using only Ni precursor and ligand without any surfactant. The Ni-MOFms exhibit good specific capacities (91.4 and 60.0 C g⁻¹ at 2 and 10 A g⁻¹, respectively) and long-term stability in 5000 cycles when used for a supercapacitor electrode.

Two-dimensional Ni-based metal–organic framework microsheets (Ni-MOFms) were synthesized via a facial one-pot solvothermal approach and exhibited good specific capacities and excellent long-term stability when used for a supercapacitor electrode.

Soluble/MOF-Supported Palladium Single Atoms Catalyze the Ligand-, Additive-, and Solvent-Free Aerobic Oxidation of Benzyl Alcohols to Benzoic Acids

Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cysteine-based metal-organic framework (MOF) was accomplished, to give a robust and crystalline solid catalyst fully characterized with the help of single-crystal X-ray diffraction (SCXRD). These results illustrate the advantages of metal speciation in ligand-free homogeneous organic reactions and the translation into solid catalysts for potential industrial implementation.

Scalable Mechanochemical Amorphization of Bimetallic Cu-Zn MOF-74 Catalyst for Selective CO2 Reduction Reaction to Methanol

Selective catalytic reduction of CO₂ to methanol has tremendous importance in the chemical industry. It mitigates two critical issues in the modern society, the overwhelming climate change and the dependence on fossil fuels. The most used catalysts are currently based on mixed copper and zinc phases, where the high surface of active copper species is a critical factor for the catalyst performance. Motivated by the recent breakthrough in the controllable synthesis of bimetallic MOF-74 materials by ball milling, we targeted to study the potential of ZnCu-MOF-74 for catalytic CO₂ reduction. Here, we tested whether the nanosized channels decorated with readily accessible and homogeneously distributed Zn and Cu metal sites would be advantageous for the catalytic CO₂ reduction. Unlike the inactive monometallic Cu-MOF-74, ZnCu-MOF-74 shows moderate catalytic activity and selectivity for the methanol synthesis. Interestingly, the postsynthetic mechanochemical treatment of desolvated ZnCu-MOF-74 resulted in amorphization and a significant increase in both the activity and selectivity of the catalyst despite the destruction of the well-ordered and porous MOF-74 architecture. The results emphasize the importance of defects for the MOF catalytic activity and the potential of amorphous MOFs to be considered as heterogeneous catalysts. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and ¹³C magic angle-spinning nuclear magnetic resonance (MAS NMR) were applied to establish quantitative structure-reactivity relationships. The apparent activation energy of rate reaction kinetics has indicated different pathway mechanisms, primarily through reverse water-gas shift (RWGS). Prolonged time on stream productivity, stability and deactivation were assessed, analysing the robustness or degradation of metal-organic framework nanomaterials. Scalable MOF production processes are making the latter more appealing within emerging industrial decarbonisation, in particular for carbon capture and utilisation (CCU) or hydrogen carrier storage. Acknowledging scale, the costs of fabrication are paramount.

Defect engineering: an effective tool for enhancing the catalytic performance of copper-MOFs for the click reaction and the A3 coupling

A series of Cu(i)-enriched and Lewis basic site-containing defect-engineering MOFs was investigated for significantly enhanced catalytic performance in the click reaction and the A³ coupling.

Bi(iii) MOFs: syntheses, structures and applications

The synthesis methods, structures and applications of Bi(iii)-based MOFs in catalysis, adsorption, fluorescence, etc. are reviewed.

A multifunctional benzothiadiazole-based fluorescence sensor for Al3+, Cr3+ and Fe3+

A benzothiadiazole-based Zn^II MOF (JXUST-3) has been synthesized, which is a good multifunctional chemosensor for the detection of Al³⁺, Cr³⁺ and Fe³⁺.

A new series of 3D lanthanide phenoxycarboxylates: synthesis, crystal structure, magnetism and photoluminescence studies

A new series of 3D Ln-carboxylates was synthesized, where the Tb one shows antiferromagnetic coupling and the Dy one shows ferromagnetic interaction, and with emission spectra combining the intra-4f emission of the Ln ions and that of the ligand.

Recent developments in the synthesis of polysubstituted pyridines via multicomponent reactions using nanocatalysts

This review describes the evolution and application of active metal-based and heterometallic NPs as efficient heterogeneous catalysts for the synthesis of pyridine derivatives by multicomponent reactions in the last decade (2010–2020).

Fluorinated solvent-assisted photocatalytic aerobic oxidative amidation of alcohols via visible-light-mediated HKUST-1/Cs-POMoW catalysis

Successful synthesis and characterization of HKUST-1/Cs-POMoW binary composite, and application in the photocatalytic aerobic oxidative amidation reaction of alcohols under light illuminating in the visible region.

The multifunctional design of metal–organic framework by applying linker desymmetrization strategy: synergistic catalysis for high CO2-epoxide conversion

A novel copper-organic framework was synthesized by a linker desymmetrization strategy. Synergistic catalysis with Lewis and Brønsted acid sites promoted a high catalytic efficiency towards the CO2-propylene oxide cycloaddition reaction.

Sequential single-crystal-to-single-crystal vapochromic inclusion in a nonporous coordination polymer: unravelling dynamic rearrangement for selective pyridine sensing

Unprecedent selective and reversible pyridine solid–vapor sequential inclusion in a nonporous Fe(ii) coordination polymer accompanied by a color change is presented. Although the internal reorganization is significant, the process remains SCSC.

Petkov P, Evans JD, Krylova S, Krylov A, Kaskel S. Tailoring adsorption induced switchability of a pillared layer MOF by crystal size engineering

The main factors affecting switchability are identified for DUT-8(Zn): energetics of the host, particle size, and desolvation stress. They influence the flexible behaviour to the same order of magnitude and should be always considered collectively.

Structural modulation of the photophysical and electronic properties of pyrene-based 3D metal–organic frameworks derived from s-block metals

Materials in which charge delocalization and migration can be tuned are critical for electronic applications.

SO2 capture enhancement in NU-1000 by the incorporation of a ruthenium gallate organometallic complex

[RuGa]@NU-1000 shows enhanced adsorption of SO2, specially at low pressures (10−3 bar) even when compared with other materials employing more expensive precious metals.

Selective oxidation of bio-based platform molecules and their conversion products over metal nanoparticle catalysts: a review

The conversion of bio-renewable raw materials into valuable products (biofuels, bifunctional carbonyls/carboxyls) that serve as the basis for biopolymers, has become one of the most important areas in the development of novel hybrid catalysts.

Backbonding contributions to small molecule chemisorption in a metal-organic framework with open copper(i) centers

Metal-organic frameworks are promising materials for applications such as gas capture, separation, and storage, due to their ability to selectively adsorb small molecules. The metal-organic framework Cu^I-MFU-4l, which contains coordinatively unsaturated copper(i) centers, can engage in backbonding interactions with various small molecule guests, motivating the design of frameworks that engage in backbonding and other electronic interactions for highly efficient and selective adsorption. Here, we examine several gases expected to bind to the open copper(i) sites in Cu^I-MFU-4l via different electronic interactions, including σ-donation, π-backbonding, and formal electron transfer. We show that in situ Cu L-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy can elucidate π-backbonding by directly probing excitations to unoccupied backbonding orbitals with Cu d-character, even for gases that participate in other dominant interactions, such as ligand-to-metal σ-donation. First-principles calculations based on density functional theory and time-dependent density functional theory additionally reveal the backbonding molecular orbitals associated with these spectroscopic transitions. The energies of the transitions correlate with the energy levels of the isolated small molecule adsorbates, and the transition intensities are proportional to the binding energies of the guest molecules within Cu^I-MFU-4l. By elucidating the molecular and electronic structure origins of backbonding interactions between electron rich metal centers in metal-organic frameworks and small molecule guests, it is possible to develop guidelines for further molecular-level design of solid-state adsorbents for energy-efficient separations of relevance to industry.

Gas-solid two-phase flow (GSF) mechanochemical synthesis of dual-metal-organic frameworks and research on electrochemical properties

As an alternative approach for conventional mechanochemical synthesis, a novel gas-solid two-phase flow (GSF) synthetic technique for the mechanochemical synthesis of dual metal-organic frameworks (DMOFs) was reported for the first time. The prepared CoMn₂(BTC)₂ was characterized by FT-IR, DTA, TG/DTG, and XRD studies. The results indicated that CoMn₂(BTC)₂ (BTC = 1,3,5-benzenetricarboxylate) was successfully synthesized after 10 min at a rate of 60 kg h^-1. CoMn₂O₄ microspheres were also prepared via the CoMn₂(BTC)₂ precursor method and characterized using FT-IR, XPS, XRD, SEM, EDS, and BET methods. The electrochemical properties of the as-prepared CoMn₂O₄ were investigated, and the GSF results showed that the microsphere electrodes of CoMn₂O₄ had a high specific capacitance (969 F g^-1) at a current density of 1 A g^-1 in 3 M aqueous KOH solution.

Next-Generation Accurate, Transferable, and Polarizable Potentials for Material Simulations

PHAHST (potentials with high accuracy, high speed, and transferability) intermolecular potential energy functions have been developed from first principles for H₂, N₂, the noble gases, and a metal-organic material, HKUST-1. The potentials are designed from the outset to be transferable to heterogeneous environments including porous materials, interfaces, and material simulations. This is accomplished by theoretically justified choices for all functional forms, parameters, and mixing rules, including explicit polarization in every environment and fitting to high quality electronic structure calculations using methods that are tractable for real systems. The models have been validated in neat systems by comparison to second virial coefficients and bulk pressure-density isotherms. For inhomogeneous applications, our main target, comparisons are presented to previously published experimental studies on the metal-organic material HKUST-1 including adsorption, isosteric heats of adsorption, binding site locations, and binding site energies. A systematic prescription is provided for developing compatible potentials for additional small molecules and materials. The resulting models are recommended for use in complex heterogeneous simulations where existing potentials may be inadequate.