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

Selective and simultaneous electrochemical detection of nitrite and nitrate ions using Ag-MOF: Food and water analyses

We report the synthesis of metal organic framework (MOF) based on Ag and phenylenediamine (C6H4(NH2)2) and its application for detection of both nitrites and nitrates. Ag-MOF modified glassy carbon electrode (GCE) revealed a significantly higher electrocatalytic activity towards selective oxidation of NO2- and reduction of NO3- over wider concentration ranges of 4-4040 μmol/L and 20-4750 μmol/L respectively and the corresponding lowest detection limits have been deduced as 0.045 μmol/L and 12 μmol/L. Interestingly, cyclic voltammetric measurements at Ag-MOF/GCE in phosphate buffer saline (pH 5.0) exhibited both anodic (NO2-) and cathodic (NO3-) peaks indicating the possibility for simultaneous detection of the two nitrogen compounds. Further, the fabricated electrode has been successfully used to determine NO2- and NO3- concentrations in beetroot, spinach, canned chicken and pond water with excellent relative standard deviation (RSD) values and recovery percentages. The results suggest the potential application of the fabricated sensor for food and environmental analyses.

Structure and Synthesizability of Iron-Sulfur Metal-Organic Frameworks

Sulfur-based metal-organic frameworks (MOFs) and coordination polymers (CPs) are an emerging class of hybrid materials that have received growing attention due to their magnetic, conductive, and catalytic properties with potential applications in electrocatalysis and energy storage. In this work, we report a high-throughput virtual screening protocol to predict the synthesizability of candidate metal-sulfur MOFs/CPs by computing the thermodynamically stable structures resulting from a particular combination of metal cluster, linker, cation, and synthetic conditions. Free energies are computed by using all-atom classical mechanical thermodynamic integration. Low-free-energy structures are refined using ab initio density functional theory, and pair distribution functions and powder X-ray diffraction patterns are calculated to complement and guide experimental structure determination. We validate the computational approach by retrospective predictions of the stable structure produced by experimental syntheses, and a subsequent screen predicts Fe4S4-BDT-TPP as a new thermodynamically stable one-dimensional (1D) CP comprising a redox-active Fe4S4 cluster, a 1,4-benzenedithiolate (BDT) linker, and a tetraphenylphosphonium (TPP) countercation. This material is experimentally synthesized, and the 1D chain structure of the crystal is confirmed using microcrystal electron diffraction. The computational screening pipeline is generically transferable to neutral and ionic MOFs/CPs comprising arbitrary metal clusters, linkers, cations, and synthetic conditions, and we make it freely available as an open source tool to guide and accelerate the discovery and engineering of novel porous materials.

Tunable Self-Assembly of Decanuclear Ni(II) Carbonato Clusters with a Hydroxyquinolinato Shell: Robust Porous Networks with Reversible Solvent-/Temperature-Driven Phase Transitions and Selective Gas Separation

The utilization of molecular metal clusters as building units of noncovalent porous materials (NPMs) is a promising strategy, combining the versatile functionality of organic and inorganic subunits with the softness and flexibility of molecular solids controlled by noncovalent interactions. However, the development of robust porous functional frameworks based on self-assembly driven by noncovalent forces is still highly challenging. Herein, we report the synthesis and characterization of a discrete decanuclear Ni(II) hydroxyquinolinato-carbonato cluster, [Ni10(μ6-CO3)4(L)12], which, depending on the crystallization conditions, self-assembles into either of two microporous frameworks: diamondoid WUT-1(Ni) and pyrite WUT-2(Ni). The transitions between both polymorphs can also be selectively triggered by temperature or exposure to vapors of a particular organic solvent, which is accompanied by the easy recovery of crystallinity by the materials from the noncrystalline phase. Moreover, both materials show excellent robustness toward various chemical environments, including air/moisture and water stability, and demonstrate interesting gas adsorption properties. Remarkably, WUT-1(Ni) exhibits significant enhancement in gas uptake compared to the previously reported isostructural Zn(II) analogue, WUT-1(Zn), representing one of the highest H2 uptakes among NPMs. In turn, tighter voids of the ultramicroporous WUT-2(Ni) framework facilitate selective interactions with gas molecules, resulting in outstanding selectivity in the adsorption of CO2 over CH4 and N2. The presented studies demonstrate the profound role of the character of metal centers on the self-assembly of isostructural nanoclusters as well as properties of the resulting microporous frameworks.

Development of Underwater Oleophobic and Underoil Hydrophobic Strontium(II)-Cyclotriphosphazene Hexacarboxylate Framework with Prewetting-Induced Switchable Wettability and Self-Cleanability for Continuous Oil-Water Mixture and Emulsion Separations

Oil spill management presents significant challenges, particularly when addressing spills that occur beneath the water's surface. In this context, Sr-HCPCP (SRMIST-2) is an innovative MOF with underwater oleophobic and underoil hydrophobic properties, incorporating enhanced coordination, a strong affinity for water and hydrophilic strontium, and a nontoxic, eco-friendly, biocompatible, and hydrophobic cyclotriphosphazene. It is designed with switchable wetting properties and exceptional chemical and thermal stability. SRMIST-2 is synthesized via a hydrothermal reaction between strontium nitrate and hexakis(4-carboxylatophenoxy)-cyclotriphosphazene. Its structure consists of edge-sharing {Sr3(COO)6(H2O)3} polyhedra that form 1-D chains, which pair to create 2-D networks that further interact with HCPCP ligands to construct a three-dimensional framework. When coated onto cotton fiber using polydopamine, the resulting CF-PDA-SRMIST-2 demonstrates excellent oil-water separation. Depending on whether it is prewetted with water or oil, it achieves separation efficiencies of 88-99%, with high flux rates (3409 Lm2-h-1 for water and 2840 Lm2-h-1 for oil) and remains effective over 15 cycles. It effectively separates oil-in-water and water-in-oil emulsions with 98% and 95% efficiency, respectively. CF-PDA-SRMIST-2 remains stable under acidic, alkaline, saline, and extreme temperature conditions. Its self-cleaning, amphiphobic properties ensure durability and reusability. With its low-cost, scalability, and eco-friendly nature, CF-PDA-SRMIST-2 is a promising material for sustainable oil spill remediation and environmental protection.

Nanoporous [Ho2(CO2)7(H2O)2]-organic frameworks for excellent catalytic performance on the cycloaddition of CO2 into epoxides and the deacetalization-Knoevenagel condensation

Designing nanoporous lanthanide-based metal-organic frameworks (MOFs) as robust heterogeneous catalysts has received a lot of interest in recent years. Herein, we successfully constructed a novel isomorphic nanoporous MOF {[Ho2(TDP) (H2O)2]·5H2O·4DMF} n (named as NUC-55, NUC = North University of China) by combining [Ho2(CO2)7(H2O)2] (abbreviated as {Ho2}) clusters with 2,4,6-tri(2,4-dicarboxyphenyl)pyridine (H6TDP) as structure-oriented multifunctional ligands under acidic solvothermal conditions. NUC-55 is a holmium(iii)-based 3D MOF with a hierarchical porous architecture containing tetragonal microchannels (0.56 nm in diameter) and octagonal nanochannels (1.79 nm in diameter), In NUC-55, plenty of Lewis acidic and basic sites, including open Ho3+ sites and Npyridine atoms, coexist. Moreover, it is worth mentioning that the void volume (∼65%) is significantly higher in NUC-55 than in most documented 3D lanthanide-based MOFs (Ln-MOFs). Catalytic experiments show that activated NUC-55 exhibits high catalytic activity in the CO2-styrene oxide cycloaddition reactions under mild conditions, with a high turnover number of 2475 and a high turnover frequency of 619 h-1. In addition, activated NUC-55 can remarkably accelerate the deacetalization-Knoevenagel condensation reactions of benzaldehyde dimethyl acetal and malononitrile. Taken together, this work can not only establish an effective self-assembly strategy for fabricating highly porous Ln-MOFs, but also provide new insights into their catalytic mechanism.

Ultrasound-assisted continuous aqueous synthesis of sulfonate, imidazolate, and carboxylate MOFs with high space time yield

The boom in metal-organic frameworks (MOFs) for applications from chemical separations and gas storage to membranes for energy conversion and storage has stimulated interest in scalable MOF production methods. Combining the increased heat and mass transfer of flow reactors with the enhanced mixing and nucleation rates of sono-chemical synthesis, we developed an ultrasound-assisted two-phase flow platform for the aqueous synthesis of MOFs spanning three ligand chemistries, sulfonate Ca-NDS (water), imidazolate ZIF-8, and carboxylate UiO-66-NH2. We show that this reactor does not foul, facilitating continuous operation at an STY of 3.4 × 104 (±1 × 103) kg m-3 day-1 of proton-conducting Ca-NDS (water). ZIF-8 and UiO-66-NH2 MOFs prepared in ultrasound-assisted flow with smaller, uniform particle sizes exhibited matched or superior gas sorption to those made in batch. These results highlight the potential of ultrasound-assisted flow synthesis for MOFs, offering enhanced nucleation alongside process intensification, and paving the way for more efficient MOF production.

Revisiting Water Oxidation Reaction with Micro Bubble Lithography (MBL) Printed ZIF-67 MOF Electrocatalysts

Microbubble-based micro-lithographic techniques have developed rapidly over the last ten years and are capable of reproducibly patterning a wide variety of soft materials and colloids, including polymers, metals, and proteins. Zeolitic imidazolate framework (ZIF) materials have attracted a great deal of research and application interest in the field of materials science because of their chemical and thermal stabilities. Furthermore, ZIF-67 has demonstrated significant potential for applications in gas adsorption, molecule separation, electrochemistry, and catalysis, which when converted into "lab-on-a-chip" platforms might produce remarkable and diverse application-oriented outcomes. This is due to their highly adjustable nanostructures. Using Co(OAc)2.4H2O and Co(NO3)2.6H2O as the metal ion sources and 2-methylimidazole as the ligand, To design ZIF-67 (composed of Co2+ ions and imidazolate ligands) is attempted. Inspired by previous results, the Micro-Bubble Lithography (MBL) approach is used to successfully demonstrate an instantaneous in situ green synthesis and micro-patterning of ZIF-67 MOFs in this work. With reasonable stability and an over-potential of 440 mV, these micro-patterns are used as microelectrodes for the electrocatalytic oxygen evolution reaction (OER) in media having different pH.

Towards effective Pd nanoparticles immobilization on NH2-MIL-53(Al) coated cellulose fiber: A stable and efficient catalyst for Suzuki reaction

The modification of cotton fibers with sodium chloroacetate, followed by the incorporation of NH2-MIL-53(Al) through covalent bonding, has been successfully developed as a support for the immobilization of palladium nanoparticles. The integration of NH2-MIL-53(Al) into cellulose enhanced the specific surface area and introduced a significant number of amino groups and pore structures, which physically isolated the metal sites. Additionally, the introduction of nitrogen heteroatoms offers numerous anchoring points, effectively preventing the loss and aggregation of the metal species. Transmission electron microscopy (TEM) analysis demonstrated that palladium nanoparticles were uniformly distributed throughout the matrix, with an average particle size of 1.29 nm. The catalytic performance of this catalyst was evaluated in the Suzuki-Miyaura reaction, which facilitates the coupling of aryl halides with arylboronic acids in the presence of 0.006 mol% palladium species. Notably, the catalyst exhibited good reusability, maintaining its catalytic performance over four cycles without a significant loss of activity.

MOF-derived Cu@Cu2O nanoclusters for photothermally enhanced Fenton-like catalytic degradation of dye pollutants

This paper presents a synthesis method for a novel octahedral Cu@Cu2O nanocluster (NAs), which is prepared by calcining Cu-BTC (metal-organic framework, 1,3,5-benzenetricarboxylate) in air, resulting in a porous carbon structure. The obtained Cu@Cu2O nanoclusters exhibit heterogeneous interfaces between Cu and Cu2O, significantly enhancing their Fenton-like catalysis and photothermal properties. Using SEM, TEM, XPS, and XRD techniques, the Cu@Cu2O NAs were comprehensively characterized. Upon near-infrared irradiation, these nanoclusters rapidly heat to 45 °C, generating reactive oxygen species (•OH) that effectively catalyze the degradation of Rhodamine B (RhB) dye. Moreover, cellular and animal experiments demonstrated that Cu@Cu2O NAs possess good biocompatibility and exhibit excellent biological safety. Overall, this study offers a promising and biocompatible material option for environmental remediation, integrating Fenton-like reactions with photothermal effects.

Unravelling the Potential of Crude Enzyme Extracts for Biocatalyst Entrapment in Metal-Organic Frameworks

To bolster the applicability of enzymes as catalysts, it is imperative not only to address their inherent fragility, particularly when used under harsh organic-synthetic reaction conditions, but also to mitigate deactivation during purification and enable applicability in a broad range of organic-synthetic transformations. Currently, the process of purification of crude enzyme extracts and subsequent heterogenization to obtain immobilized biocatalysts often leads to partial enzyme deactivation and represents, at least in part, a resource-intensive process that is driving up the overall production efforts. To tackle both the enzyme fragility and deactivation during purification and immobilization, we propose the direct use of crude enzyme extracts obtained from cell lysis instead of pure enzymes and their entrapment in metal-organic framework (MOF) structures. We focus on three enzyme types with varying sensitivities: aldoxime dehydratase, imine reductase, and lipase. We evaluate the effects of different metal sources (Al, Fe, Co, Ni, Cu, and Zn), their oxidation state and counterions, and MOF synthesis parameters on enzyme stability and activity during their entrapment in the MOF structures. Based on this, we optimize protocols for enzyme entrapment in Fe-MIL-88A, Fe-MIL-100, Zn-MOF-74, and Zn-ZIF-8 and develop a fast-aqueous room temperature synthesis of Al-MIL-53. Investigation of the biocatalytic performance of the enzyme@MOF biocomposites suggests that enzyme entrapment in MOFs using crude enzyme extracts can effectively maintain enzyme activity and stability in various catalytic reactions, offering a perspective for an efficient pathway for industrial applications.

Synthesis of metal-organic framework functionalized macroscopic flow-through precipitate tubes

The guided growth and the composition control of the well-known chemical garden tubular structures have been widely studied in the literature. However, the applicability of these macroscopic hollow precipitate tubes (e.g., for catalysis, sensorics etc.) is still limited, since these pipes originally do not have a flow-through character, thus the functionalization of these tubes is difficult to implement. In this work, our goal was to design a novel reactor that enables the production of these flow-through precipitate pipes with robust junctions, and thus their functionalization for further applications. We successfully built the reactor and synthesized such pipes. Their flow-through character was proven in case of various template tubes which were produced by injecting one of the reactant solutions into the pool of the other in three dimensions. After the production of the template tubes, we attempted to decorate the surface with sodalite type ZIF-8 crystals, which are of great interest thanks to their beneficial properties (porous structure, huge specific surface area etc.) for catalysis or gas separation. The surface functionalization was carried out by exchanging the reactant solutions inside and outside the template precipitate tubes. Due to the semi-permeable nature of the tube wall, the reactants could diffuse through the membrane and react with each other. This way we produced (most probably sodalite type) ZIF-8 crystals on the inner tube surface and thus functionalized it.

Evaluation of Semiempirical Quantum Mechanical Methods for Zr-Based Metal-Organic Framework Catalysts

Zr-based metal-organic frameworks (MOFs) are typically employed in heterogeneous catalysis due to their porosity, chemical and thermal stability, and well-defined active sites. Density functional theory (DFT) is the workhorse to compute their electronic structure; however, it becomes very costly when dealing with reaction mechanisms involving large unit cells and vast configurational spaces. Semiempirical quantum mechanical (SQM) methods appear as an alternative approach to simulate such chemical systems at low computational cost, but their feasibility to model catalysis with MOFs is still unexplored. Thus, here we present a benchmark study on UiO-66 to evaluate the performance of SQM methods (PM6, PM7, GFN1-xTB, GFN2-xTB) against hybrid DFT (M06). We evaluate defective nodes, ligand exchange reactions, barrier heights, and host-guest interactions with metal nanoclusters. Despite some caveats, GFN1-xTB on properly constrained models is the best SQM method across all studied properties. Under proper supervision, this protocol holds promise for application in exploratory high-throughput screenings of Zr-based MOF catalysts, subject to further refinement with more accurate methods.

Strategic Secondary Ligand Selection for Enhanced Pore-Type Construction and Water Purification Capacity in Zeolitic Imidazolate Frameworks

Selective ligand removal (SeLiRe) is a powerful strategy for constructing novel pore-type and ligand-defective structures in metal-organic frameworks (MOFs), but few studies have focused on the effect of secondary ligands with different functional groups on this process. We synthesized versions of zeolitic imidazolate framework-8 with six different secondary ligands and comprehensively investigated their pore-type structures after SeLiRe treatment. Their pore volume, size, and distribution are closely related to the respective organic functional groups on the secondary ligands. NH2-functionalized ligands tend to form larger domains and have weaker Zn-Nβ covalent bonds, which facilitate the removal process and the construction of larger cavities. Among the six secondary ligands, 5-bromo-1H-benzo[d]imidazol-2-amine exhibits the composite pore-type structure with hierarchical micro- and mesopores, achieving the highest methylene blue adsorption capacity of 28.1 mg g-1. Compared to traditional sodalite-type ZIFs, this results in a 53-fold increase in water pollutant adsorption. This work highlights the crucial role of the secondary ligand in the SeLiRe strategy and provides valuable insights for designing other hierarchical porous hybrid structures.

The structuring of porous reticular materials for energy applications at industrial scales

Reticular synthesis constructs crystalline architectures by linking molecular building blocks with robust bonds. This process gave rise to reticular chemistry and permanently porous solids. Such precise control over pore shape, size and surface chemistry makes reticular materials versatile for gas storage, separation, catalysis, sensing, and healthcare applications. Despite their potential, the transition from laboratory to industrial applications remains largely limited. Among various factors contributing to this translational gap, the challenges associated with their formulation through structuring and densification for industrial compatibility are significant yet underexplored areas. Here, we focus on the shaping strategies for porous reticular materials, particularly metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), to facilitate their industrial application. We explore techniques that preserve functionality and ensure durability under rigorous industrial conditions. The discussion highlights various configurations - granules, monoliths, pellets, thin films, gels, foams, and glasses - structured to maintain the materials' intrinsic microscopic properties at a macroscopic level. We examine the foundational theory and principles behind these shapes and structures, employing both in situ and post-synthetic methods. Through case studies, we demonstrate the performance of these materials in real-world settings, offering a structuring blueprint to inform the selection of techniques and shapes for diverse applications. Ultimately, we argue that advancing structuring strategies for porous reticular materials is key to closing the gap between laboratory research and industrial utilization.

Polymer Encapsulated Framework Materials for Enhanced Gas Storage and Separations

Within the broader field of energy storage, polymer-encapsulated framework (PEF) materials have witnessed remarkable growth in recent years, with transformative implications for diverse applications. This comprehensive review discusses in detail the latest advancements in the design, synthesis, and applications of PEFs in gas storage and separations. Following a thorough survey of existing literature, the article delves into mechanistic considerations and foundational principles governing PEF synthesis. Emphasis is placed on covalent and coordinative covalent grafting methods, physical blending, nonsolvent utilization, and various vapor deposition techniques. The discussion critically evaluates the advantages and disadvantages of these synthesis approaches, considering factors such as grafting density, coating thickness, and other physical properties relevant to processability and stability in comparison to traditional framework materials. Special attention is given to the impact of polymer coatings on gas adsorption analysis. Finally, notable accomplishments and advancements in the PEF field, including mixed matrix membrane (MMM) technology, improvements in framework form factors, and enhanced chemical and mechanical stability are summarized. This review concludes by offering valuable perspective for researchers, highlighting gaps and challenges that confront the current state-of-the-art in PEF materials, paving the way for future innovations that are poised to help address global energy challenges.

Sight into a Rare-Earth-Based Catalyst with Spatial Confinement Effect from the Perspective of Electronic Structure

Rare-earth elements include 15 kinds of lanthanides as well as Sc and Y elements. Interestingly, the special electronic configuration of a lanthanide rare earth is [Xe]4fn5d0-16s2 (n = 0-14), which results in rare-earth materials' unique activity in such areas as thermal catalysis, electrocatalysis, photocatalysis, etc. It is worth noting that a class of materials with spatial confinement effects are playing an increasingly important role in the catalytic performance; especially, the construction of hollow multishelled structures (HoMSs) can further enhance the activity of rare-earth catalytic materials. In this review, we discuss in depth the important roles of the rare-earth 4f5d electronic structure. Subsequently, this review systematically summarizes the synthesis methods of rare-earth HoMSs and their research progress in the field of catalysis and specifically introduces the advanced characterization and analysis methods of rare-earth HoMSs. Finally, the research directions, application prospects, and challenges that need to be focused on in the future of rare-earth-based HoMSs are discussed and anticipated. We believe that this review will not only inspire more creativity in optimizing the local electronic structure and spatial confinement structure design of rare-earth-based catalysts but also provide valuable insights for designing other types of catalysts.

Catalytic Efficacy of a 2D Chemically Robust MOF for the Synthesis of Bioactive Diindolylmethane (DIM)-Based Drug Molecules

Synthesis of biologically and pharmaceutically important drugs via organic transformations in one pot under mild conditions with efficient catalysts is of significant interest in terms of practical utility. Though metal-organic frameworks (MOFs) prove their efficiencies in various catalytic reactions, synthesis of drug molecules employing MOF catalysts is still in its early stage, in fact, restricted to only 1,4-Dihydropyridines (1,4-DHP) based drug molecules synthesis. Although the Friedel-Crafts alkylation (FCA) reaction is one of the oldest reactions with a significant impact on drug molecules synthesis, surprisingly this reaction triggered by MOF catalyst is largely unexplored. Herein, we report a robust framework, MOF: IITKGP-55, synthesized solely in aqueous medium, which exhibits its superior catalytic efficiencies for one-pot FCA reaction with the well tolerance of various substrate scopes. Most importantly, based on this catalytic reaction, three drug molecules with bioactive diindolylmethane (DIM) core are synthesized for the first time, which was never realized by employing any sort of heterogeneous catalysts. Moreover, Arundine drug is crystallized and an in-depth crystallographic analysis is performed. The superior catalytic efficiencies with excellent framework robustness highlight the potentiality of the developed framework and unwrap a new avenue for drug molecule synthesis via FCA reaction by employing heterogeneous catalysts.

Local order, disorder, and everything in between: using 91Zr solid-state NMR spectroscopy to probe zirconium-based metal-organic frameworks

Characterization of metal centers in metal-organic frameworks (MOFs) is critical for rational design and further understanding of structure-property relationships. The short-range structure about Zr atoms is challenging to properly elucidate in many Zr MOFs, particularly when local disorder is present. Static 91Zr solid-state NMR spectra of the seven zirconium MOFs UiO-66, UiO-66-NH2, UiO-67, MOF-801, MOF-808, DUT-68 and DUT-69 have been acquired at high magnetic fields of 35.2 T and 19.6 T, yielding valuable information on the local structure, site symmetry and order about Zr. 91Zr NMR is very sensitive to differences in MOF short-range structure caused by guest molecules, linker substitution and post-synthetic treatment. Complementary density functional theory (DFT) calculations assist in the interpretation and assignment of 91Zr solid-state NMR spectra, lend insight into structural origins of 91Zr NMR parameters and enable determination of local Zr coordination environments. This approach can be extended to many other materials containing zirconium.

Vapor-Deposited MOF for Low-k Dielectric Seamless High-Aspect-Ratio Interconnect Gap Fill

A vapor-phase ZIF-8 MOF deposition procedure for seamless high-aspect-ratio interconnect gap fill has been developed with a short process time (15 min) at a 160 °C process temperature. This is the most rapid documented vapor technique to produce a MOF film and is made possible by a higher process temperature and a low background H2O environment. The process consists of ALD of a thin (<5 nm) ZnO film followed by conversion to ZIF-8 in an organic linker (ALD + soak cycle). This method exhibited complete ZnO to MOF conversion, as well as MOFs with low-k (k ∼ 2.6). Dielectric gap fill was investigated utilizing patterned samples with widths ranging from 40 to 400 nm. Both high aspect ratio gap fill and multiple aspect ratio gap fills were shown with no residual ZnO. The MOF gap-fill process could be attributed to the reflow behavior of 2-methylimidazole-ZnO reaction intermediates or nascent product. The MOF was found to be stable at 400 °C under vacuum (1 × 10-2 Torr), which is comparable to other low-k dielectrics. Fluorine plasma etch resistance was tested for the ZIF-8 MOF in comparison to bare Si, SiCOH, and SiO2; the MOF was proven to be the best in resisting plasma etch. This work demonstrated that ALD + soak cycle conversion low-k ZIF-8 MOF films have the potential to be a plasma-free vapor-phase seamless gap fill for high aspect ratio features to be employed in logic and memory device fabrication, as well as three-dimensional heterogeneous integration (3DHI).

Reusable Ni-Immobilized MOF Catalyst for Dehydrogenation of N-Heterocycles Under Milder Conditions

Herein, we have demonstrated the design and synthesis of a novel Ni-immobilized MOF as heterogeneous catalyst for the dehydrogenation of N-heterocycles. A series of five and six-membered N-heteroarenes bearing one or more heteroatoms were synthesized in up to 98 % yield (>33 examples). Late stage functionalization to the synthesis of β-glucuronides inhibitor, antimalarial drug quinine, and the nonsteroidal anti-inflammatory drug (NSAID) indomethacin were obtained under milder reactions conditions. A series of mechanistic studies revealed the detection of H2 and H2O2 during the progress of the reactions and suggested the involvement of enamine-imine intermediate species for sequential dehydrogenation. Detailed characterization of the fresh catalyst and reused catalyst were performed using SEM, TEM, BET, PXRD, and EDX elemental mappings. The catalyst could be recycled up to four-times without much loss in catalytic activities. In-situ formed defects, pore size enlargement and additional Lewis acid sites within catalyst nanocrystals assisted in attaining high activity and selectivity to N-heteroarenes.

Functionalization of monolithic MOF thin films with hydrocarbon chains to achieve superhydrophobic surfaces with tunable water adhesion strength

While the accessible pores render an enormous variety of functionalities to the bulk of metal-organic frameworks (MOFs), the outer surfaces exposed by these crystalline materials also offer unique characteristics not available when using conventional substrates. By grafting hydrocarbon chains to well-defined MOF thin films (SURMOFs) prepared using layer-by-layer methods, we were able to fabricate superhydrophobic substrates with static water contact angles over 160°. A detailed theoretical modelling of the hydrocarbon chains grafted on the outer SURMOF surface with well-defined spacing between anchoring points reveals that the grafted hydrocarbon chains behave similarly to polymer brushes during wetting, where conformational entropy is traded with mixing entropy. The chains are coiled and can access many different conformations, as evidenced directly by infrared spectroscopy. The entropic contributions from the coiled state lead to a pronounced reduction of the surface free energy, rendering superhydrophobic properties to the functionalized SURMOFs. On the other side, the water adhesion strength could be decreased by increasing the surface roughness on the nanometer scale.

Integrating Ni-MOF/g-C3N4/chitosan derived S-scheme photocatalyst for efficient visible light photodegradation of tetracycline and antibacterial activities

Nickel MOF (Ni-MOF) nanoparticles were successfully anchored onto a polymeric graphitic carbon nitride (g-C3N4) and Chitosan nanostructure (NS) using an eco-friendly and straightforward synthesis method. These newly fabricated photocatalysts were thoroughly characterized with standard techniques, revealing that the nanoscale Ni-MOF particles were uniformly deposited on the sheet-like g-C3N4 matrix. This configuration demonstrated excellent antimicrobial properties and outstanding photodegradation of tetracycline hydrochloride under visible light exposure. The MOF@GC photocatalyst exhibited robust bactericidal activity against pathogens like Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Additionally, it achieved superior visible-light-driven degradation of tetracycline in a significantly shorter time compared to other studies, with approximately 96% of the tetracycline being degraded in just 70 min under visible light. These findings suggest that the effective deposition of Ni-MOF onto the g-C3N4 structure reduces the recombination rate of photogenerated electrons and holes, thereby enhancing the photocatalytic efficiency of pure g-C3N4 under visible light. The proposed catalytic mechanism, informed by valence band (VB) and conduction band (CB) data from cyclic voltammetry measurements, further supports this conclusion. The MOF@GC photocatalyst is a promising nanostructured material for antimicrobial applications and visible-light-driven photocatalysis.

Chemospecific Heterostructure and Heteromaterial Assembly of Metal-Organic Framework Nanoparticles

Nanoparticles of highly porous metal-organic frameworks (MOFs) are some of the most exciting nanomaterials under development, with potential applications that range from biomedicine and catalysis to adsorption technologies. However, our synthetic methodologies to functionalize and manipulate MOF nanoparticles (NPs) are less well developed than they might be. Here we create MOF NPs derivatized with hydrazone units on their exterior, enabling chemospecific reversible dynamic covalent modification of structures on the external surface. Pairwise combinations of nanometer-sized building blocks with complementary dynamic covalent surface units can be used to prepare heterostructure assemblies (i.e., two MOFs with different structures and morphologies) and heteromaterial assemblies (a MOF with a nanoparticle of another kind, in this case gold) in which the directional molecular-level dynamic covalent links demand intimate mixing of the two nanoscale components. Crucially, the defining characteristic of the MOF components─their porosity─is minimally affected by the external functionalization and interparticle linking. The development of atomically precise dynamic covalent functionalization on the external surface of MOF NPs opens up new avenues for programmable frameworks with responsive behaviors and modular assembly of porous materials with precise control over the spatial organization of multiple nanoscale building blocks.

Defect-derived catalytic sites in Ce/Zr-UiO-66 for degradation of hexachlorobenzene

It is of great significance to develop catalysts for the degradation of hexachlorobenzene from the industrial thermal process. In this paper, formic acid was used as a modulator to generate defect sites in Ce/Zr-UiO-66 with intrinsic Brønsted acidity. The defective formate ligands were removed through methanol-water vapor treatment to expose additional open metal sites with Lewis acidity. The intrinsic Brønsted acid sites of the resulting Ce/Zr-UiO-66-FA-P achieved a hexachlorobenzene degradation efficiency of 99.5% at 250 °C. The generated Lewis acid sites facilitated the C-C cleavage of degradation intermediates. More than 95.0% of the final products were CO2/CO, coupled with chlorinated alkanes/alkenes, which outperformed other benchmark metal oxide catalysts. The Ce/Zr-UiO-66-FA-P catalyst maintained its catalytic activity in the model industrial flue gas and humid environment. The degradation pathway of hexachlorobenzene was tracked using in situ FT-IR spectra.

2D Cerium-Organic Frameworks as an Efficient Heterogeneous Catalyst for the Synthesis of 1,4-Dihydropyridines via Hantzsch Reaction

Herein, a new two-dimensional (2D) Ce-organic frameworks (referred to as SLX-4) was achieved by traditional solvothermal conditions. Initial studies of SLX-4 toward Hantzsch reaction showed that good catalytic activity can be obtained under mild conditions, giving the desired 1,4-dihydropyridines in moderate to high yields. The catalyst could be reused at least 4 times keeping good catalytic activity. Moreover, compared to the previously reported MOFs catalysts for Hantzsch reactions, SLX-4 was stable in most acidic and basic environment, and gave comparable yield.

Diffusion-programmed catalysis in nanoporous material

In the realm of heterogeneous catalysis, the diffusion of reactants into catalytically active sites stands as a pivotal determinant influencing both turnover frequency and geometric selectivity in product formation. While accelerated diffusion of reactants can elevate reaction rates, it often entails a compromise in geometric selectivity. Porous catalysts, including metal-organic and covalent organic frameworks, confront formidable obstacles in regulating reactant diffusion rates. Consequently, the chemical functionality of the catalysts typically governs turnover frequency and geometric selectivity. This study presents an approach harnessing diffusion length to achieve improved selectivity and manipulation of reactant-active site residence time at active sites to augment reaction kinetics. Through the deployment of a thin film composed of a porous metal-organic framework catalyst, we illustrate how programming reactant diffusion within a cross-flow microfluidic catalytic reactor can concurrently amplify turnover frequency (exceeding 1000-fold) and enhance geometric selectivity ( ~ 2-fold) relative to conventional nano/microcrystals of catalyst in one-pot reactor. This diffusion-programed strategy represents a robust solution to surmount the constraints imposed by bulk nano/microcrystals of catalysts, marking advancement in the design of porous catalyst-driven organic reactions.

Supramolecular Chemistry in Metal-Organic Framework Materials

Far from being simply rigid, benign architectures, metal-organic frameworks (MOFs) exhibit diverse interactions with their interior environment. From developing crystal sponges to studying reactions in framework materials, the role of both supramolecular chemistry and framework structure is evident. We explore the role of supramolecular chemistry in determining framework…guest interactions and attempts to understand the dynamic behavior in MOFs, including attempts to control pore behavior through the incorporation of mechanically-interlocked molecules. Appreciating and understanding the role of supramolecular interactions and dynamic behavior in metal-organic frameworks emerge as important directions for the field.

A coordination polymer with a silylene-supported Pd6 core as an efficient heterogeneous hydrogenation catalyst

A hexanuclear palladium cluster supported by two silylene units was readily linked by molecules of a linear ditopic isocyanide to afford a coordination polymer that retained the core Pd6(SiPh2)2Cl2 framework. The obtained coordination polymer exhibited good performance as a heterogeneous catalyst in the hydrogenation of various alkenes in common organic solvents and in protic solvents such as H2O. Furthermore, the obtained coordination polymer showed sufficient stability during the hydrogenation in order for it to be recycled and reused.

Modification of ZIF-8 Membranes for Gas Separation Using X-ray Radiation

We report an X-ray radiation-induced modification of the structure and gas permeation behavior of ZIF-8 membranes. With 300 min irradiation time, CO2 permeance decreases by only 9 %, while N2 and CH4 permeances reduce by 75 and 65 %, respectively, leading to 3.7- and 2.6-fold enhancements in ideal selectivity for CO2/N2 and CO2/CH4.

Human interpretable structure-property relationships in chemistry using explainable machine learning and large language models

Explainable Artificial Intelligence (XAI) is an emerging field in AI that aims to address the opaque nature of machine learning models. Furthermore, it has been shown that XAI can be used to extract input-output relationships, making them a useful tool in chemistry to understand structure-property relationships. However, one of the main limitations of XAI methods is that they are developed for technically oriented users. We propose the XpertAI framework that integrates XAI methods with large language models (LLMs) accessing scientific literature to generate accessible natural language explanations of raw chemical data automatically. We conducted 5 case studies to evaluate the performance of XpertAI. Our results show that XpertAI combines the strengths of LLMs and XAI tools in generating specific, scientific, and interpretable explanations.

A Chemically Robust 2D Ni-MOF as an Efficient Heterogeneous Catalyst for One-Pot Synthesis of Therapeutic and Bioactive 2-Amino-3-Cyano-4H-Pyran Derivatives

Despite possessing numerous catalytic advantages of MOFs, developing 2D frameworks having excellent chemical stability along with new catalytic properties remains a grand challenge. Herein, by employing a mixed ligand synthetic approach, we have constructed a 2D Ni-MOF, IITKGP-52, which exhibits excellent framework robustness in open air, water, as well as over a wide range of aqueous pH solutions (2-12). Benefitting from its robustness and abundant Lewis acidic open metal sites (OMSs), IITKGP-52 is explored in catalyzing the heterogeneous three-component condensation reaction for the tandem synthesis of bioactive 2-amino-3-cyano-4H-pyran derivatives with low catalytic loading, greater compatibility for a wide range of substrates, excellent recyclability and superior catalytic efficiency than the previously employed homo and heterogeneous systems. IITKGP-52 inaugurates the employment of MOF-based catalysts for one-pot synthesis of therapeutic and bioactive 2-amino-3-cyano-4H-pyran derivatives.

Recent advances in heterogeneous porous Metal-Organic Framework catalysis for Suzuki-Miyaura cross-couplings

Suzuki-Miyaura coupling (SMC), a crucial C-C cross-coupling reaction, is still associated with challenges such as high synthetic costs, intricate work-ups, and contamination with homogeneous metal catalysts. Research intensely focuses on strategies to convert homogeneous soluble metal catalysts into insoluble powder solids, promoting heterogeneous catalysis for easy recovery and reuse as well as for exploring greener reaction protocols. Metal-Organic Frameworks (MOFs), recognized for their high surface area, porosity, and presence of transition metals, are increasingly studied for developing heterogeneous SMC. The molecular fence effect, attributed to MOF surface functionalization, helps preventing catalyst deactivation by aggregation, migration, and leaching during catalysis. Recent reports demonstrate the enhanced catalytic activity, selectivity, stability, application scopes, and potential of MOFs in developing greener heterogeneous synthetic methodologies. This review focuses on the catalytic applications of MOFs in SMC reactions, emphasizing developments after 2016. It critically examines the synthesis and incorporation of active metal species into MOFs, focusing on morphology, crystallinity, and dimensionality for catalytic activity induction. MOF catalysts are categorized based on their metal nodes in subsections, with comprehensive discussion on Pd incorporation strategies, catalyst structures, optimal SMC conditions, and application scopes, concluding with insights into challenges and future research directions in this important emerging area of MOF applications.

Stoichiometry-Regulated Synthesis of Three Adenine-Based Coordination Polymers for Catalytic Excellence through the Synergistic Amalgamation of Coordinative Unsaturation and Lewis Basic Sites

Nucleobase adenine is a promising candidate for synthesizing fascinating coordination polymers (CPs) due to the presence of five potential metal-ion binding centers. In recent years, CPs have emerged as promising Lewis acid-base centers containing heterogeneous catalysts for a wide range of organic transformations. However, the crucial role of stoichiometric regulations of the starting materials and their consequential impact on catalytic performance are rarely studied. Herein, we have synthesized three adenine (Ad)-based cadmium CPs with 5-nitro isophthalic acid (H2NIPA) by a mixed linker approach by tuning the substrate's stoichiometric proportion. The single-crystal X-ray diffraction analysis of the synthesized CPs, SSICG-11, [Cd(Ad)(NIPA)(H2O)]·H2O; SSICG-12, [Cd(Ad)2(NIPA)(H2O)]; and SSICG-13, [Cd4(Ad)(NIPA)3]·H2O·DMF, reveals that these three compounds exhibit distinct asymmetric units, each reflecting varying precursor proportions. Due to their high chemical stability and the presence of both Lewis acidic-basic sites, SSICG-11-13 were employed as heterogeneous catalysts for Hantzsch and Strecker reactions. However, SSICG-12 is more efficient due to its capacity to form an open metal sites (OMSs) and the presence of a higher number of adenine moieties. Overall, this study demonstrated the stoichiometrically controlled synthesis of adenine-based CPs and dissected their efficiency as a heterogeneous catalyst by correlating their structures and compositions.

Antimicrobial zeolites and metal-organic frameworks

The current surge in antibiotic resistance and the emergence of pandemics have created an urgent need for novel antimicrobial strategies. The controlled release of antimicrobial active principles remains the most viable strategy to date, and transition metal ions currently represent the main alternative to antibiotics. In this review, we explore the potential of two types of materials, zeolites and metal-organic frameworks (MOFs), for the controlled release of antimicrobial active principles, notably transition metal ions. These materials have unique crystalline microporous structures that act as reservoirs, enabling sustained bactericidal effects in various applications such as coatings, packaging, and medical devices. However, there are currently no convenient and standardised methods for evaluating their metal ion release and antimicrobial efficacy. This work discusses analytical techniques and the proposed mechanisms of action while highlighting recent advances in film, membrane, and coating technologies. By addressing the current limitations, microporous materials can revolutionise antimicrobial approaches, offering enhanced effectiveness and long-term sustainability.

Metal-Organic Framework and Covalent-Organic Framework-Based Aerogels: Synthesis, Functionality, and Applications

Metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs)-based aerogels are garnering significant attention owing to their unique chemical and structural properties. These materials harmoniously combine the advantages of MOFs and COFs-such as high surface area, customizable porosity, and varied chemical functionality-with the lightweight and structured porosity characteristic of aerogels. This combination opens up new avenues for advanced applications in fields where material efficiency and enhanced functionality are critical. This review provides a comparative overview of the synthetic strategies utilized to produce pristine MOF/COF aerogels as well as MOF/COF-based hybrid aerogels, which are functionalized with molecular precursors and nanoscale materials. The versatility of these aerogels positions them as promising candidates for addressing complex challenges in environmental remediation, energy storage and conversion, sustainable water-energy technologies, and chemical separations. Furthermore, this study discusses the current challenges and future prospects related to the synthesis techniques and applications of MOF/COF aerogels.

Metal-organic frameworks of p-hydroxybenzoic acid: synthesis, structure and ring opening polymerization capability

Two new, isostructural, metal-organic frameworks {[Co(O2CC6H4O)(DMF)]2} n and {[Mn(O2CC6H4O)(DMF)]2} n have been synthesised and structurally characterized. Use of p-hydroxybenzoic acid resulted in a three-dimensional MOF featuring a linker with a carboxylic group and a para-hydroxyl group. Ring opening polymerization of ε-caprolactone and δ-valerolactone has been performed using these MOFs as catalysts, and results compared with the known zinc MOF Zn(O2CC6H4O). The resulting products are predominantly cyclic polymers. The manganese and zinc MOFs exhibit significant recyclability during ring opening polymerization.

Recent Advances in Immobilizing and Benchmarking Molecular Catalysts for Artificial Photosynthesis

Transition metal complexes have been widely used as catalysts or chromophores in artificial photosynthesis. Traditionally, they are employed in homogeneous settings. Despite their functional versatility and structural tunability, broad industrial applications of these catalysts are impeded by the limitations of homogeneous catalysis such as poor catalyst recyclability, solvent constraints (mostly organic solvents), and catalyst durability. Over the past few decades, researchers have developed various methods for molecular catalyst heterogenization to overcome these limitations. In this review, we summarize recent developments in heterogenization strategies, with a focus on describing methods employed in the heterogenization process and their effects on catalytic performances. Alongside the in-depth discussion of heterogenization strategies, this review aims to provide a concise overview of the key metrics associated with heterogenized systems. We hope this review will aid researchers who are new to this research field in gaining a better understanding.

In situ construction of S-scheme heterojunctions between BiOCl and Bi-MOF for enhanced photocatalytic CO2 reduction and pollutant degradation

Recently, photocatalytic technology has been widely used as a sustainable method to address environmental pollution issues. Herein, BiOCl/Bi-MOF (BOC/Bi-MOF) based semiconductor photocatalysts with S-scheme heterojunction were fabricated by an in situ growth method, and the photocatalytic activity of the materials was explored for CO2 reduction and pollutant degradation. As confirmed by density functional theory calculations and physiochemical characterizations, the established S-scheme heterojunction confers enhanced carrier separation efficiency and retention of redox capability to the BOC/Bi-MOF. Through an improved combination of charge separation and surface reactions, the prepared BOC/Bi-MOF efficiently reduces CO2 solely to CO. The heterojunction as catalyst is more durable and effective than any of its single component. The CO evolution rate of the optimized composite catalyst was 7.66 and 33.10 times of those of BiOCl and Bi-MOF, respectively. In addition, BOC/Bi-MOF exhibits a high efficiency in the photocatalytic degradation of the pollutant rhodamine B (RhB) in aqueous environments, and the pollutant was completely removed within 20 min. Due to the generation of interfacial potential differences, the internal electric field (IEF) generation at heterogeneous interfaces facilitates the separation and transfer of photogenic charges. This work demonstrated a practical and effective route for in situ growth of S-scheme heterojunctions with high efficiencies in CO2 reduction and RhB degradation.

A novel pillar-layered MOF with urea linkers as a capable catalyst for synthesis of new 1,8-naphthyridines via the anomeric-based oxidation

Metal-based catalysts play an essential role in organic chemistry and the chemical industry. This research designed and successfully synthesized a pillar-layered metal-organic framework (MOF) with the urea linkers, namely Basu-HDI, as a novel and efficient heterogeneous catalyst. Various techniques such as FT-IR, EDX, elemental mapping, SEM, XRD, BET, and TGA/DTA studied its structure and morphology. Then, we investigated the synthesis of new 1,8-naphthyridines utilizing Basu-HDI in mild conditions via a one-pot, three-component tandem Knoevenagel/Michael/ cyclization/anomeric-based oxidation reaction. Final products were achieved by anomeric-based oxidation without employing an oxidation agent. Remarkably, this tandem process gave a good range of new 1,8-naphthyridines with high yields in a short reaction time. The pure products were confirmed by FT-IR, 1H NMR, 13C NMR, and mass spectrometry techniques. Moreover, the introduced catalyst showed good efficiency and stability and can be reused four times without significantly reducing efficiency.

Steering diffusion selectivity of chemical isomers within aligned nanochannels of metal-organic framework thin film

The movement of molecules (i.e. diffusion) within angstrom-scale pores of porous materials such as metal-organic frameworks (MOFs) and zeolites is influenced by multiple complex factors that can be challenging to assess and manipulate. Nevertheless, understanding and controlling this diffusion phenomenon is crucial for advancing energy-economic membrane-based chemical separation technologies, as well as for heterogeneous catalysis and sensing applications. Through precise assessment of the factors influencing diffusion within a porous metal-organic framework (MOF) thin film, we have developed a chemical strategy to manipulate and reverse chemical isomer diffusion selectivity. In the process of cognizing the molecular diffusion within oriented, angstrom-scale channels of MOF thin film, we have unveiled a dynamic chemical interaction between the adsorbate (chemical isomers) and the MOF using a combination of kinetic mass uptake experiments and molecular simulation. Leveraging the dynamic chemical interactions, we have reversed the haloalkane (positional) isomer diffusion selectivity, forging a chemical pathway to elevate the overall efficacy of membrane-based chemical separation and selective catalytic reactions.

Accelerating Discovery of Mechanically Stable Metal-Organic Frameworks for Vinylidene Fluoride Storage by Active Learning

Metal-organic frameworks (MOFs) are versatile nanoporous materials for a wide variety of important applications. Recently, a handful of MOFs have been explored for the storage of toxic fluorinated gases (Keasler et al. Science, 2023, 381, 1455), yet the potential of a great number of MOFs for such an environmentally sustainable application has not been thoroughly investigated. In this work, we apply active learning (AL) to accelerate the discovery of hypothetical MOFs (hMOFs) that can efficiently store a specific fluorinated gas, namely, vinylidene fluoride (VDF). First, a force field was developed for VDF and utilized to predict the working capacities (ΔN) of VDF in an initial data set of 4502 MOFs from the computation-ready experimental MOF (CoRE-MOF) database that successfully underwent featurization and grand-canonical Monte Carlo simulations. Next, the initial data set was diversified by Greedy sampling in an unexplored sample space of 119,387 hMOFs from the ab initio REPEAT charge MOF (ARC-MOF) database. A budget of 10,000 samples (i.e., <10% of total ARC-MOFs) was selected to train a random forest model. Then, ΔN in the unlabeled ARC-MOFs were predicted and top-performing ones were validated by simulations. Integrating with the stability requirement, mechanically stable ARC-MOFs were finally identified, along with high ΔN. Furthermore, by Pareto-Frontier analysis, we revealed that long linear linkers can enhance ΔN, while bulkier multiphenyl linkers or interpenetrated frameworks improve mechanical strength. From this work, we efficiently discover top-performing MOFs for VDF storage by AL and also demonstrate the importance of integrating stability to identify stable promising MOFs for a practical application.

Ligand engineering enhances (photo) electrocatalytic activity and stability of zeolitic imidazolate frameworks via in-situ surface reconstruction

The current limitations in utilizing metal-organic frameworks for (photo)electrochemical applications stem from their diminished electrochemical stability. In our study, we illustrate a method to bolster the activity and stability of (photo)electrocatalytically active metal-organic frameworks through ligand engineering. We synthesize four distinct mixed-ligand versions of zeolitic imidazolate framework-67, and conduct a comprehensive investigation into the structural evolution and self-reconstruction during electrocatalytic oxygen evolution reactions. In contrast to the conventional single-ligand ZIF, where the framework undergoes a complete transformation into CoOOH via a stepwise oxidation, the ligand-engineered zeolitic imidazolate frameworks manage to preserve the fundamental framework structure by in-situ forming a protective cobalt (oxy)hydroxide layer on the surface. This surface reconstruction facilitates both conductivity and catalytic activity by one order of magnitude and considerably enhances the (photo)electrochemical stability. This work highlights the vital role of ligand engineering for designing advanced and stable metal-organic frameworks for photo- and electrocatalysis.

Synthesis, Characterization and Photophysical Properties of a New Family of Rare-Earth Cluster-Based Metal-Organic Frameworks

In this work, nine new rare-earth metal-organic frameworks (RE-MOFs, where RE=Lu(III), Yb(III), Tm(III), Er(III), Ho(III), Dy(III), Tb(III), Gd(III), and Eu(III)) isostructural to Zr-MOF-808 are synthesized, characterized, and studied regarding their photophysical properties. Materials with high crystallinity and surface area are obtained from a reproducible synthetic procedure that involves the use of two fluorinated modulators. At the same time, these new RE-MOFs display tunable photoluminescent properties due to efficient linker-to-metal energy transfer promoted by the antenna effect, resulting in a series of RE-MOFs displaying lanthanoid-based emissions spanning the visible and near-infrared regions of the electromagnetic spectrum.

Installation of Copper(I) and Silver(I) Sites into TREN-Based Porous Organic Cages via Postsynthetic Metalation

Porous organic cages (POCs) and metal-organic polyhedra (MOPs) function as zero-dimensional porous materials, able to mimic many functions of insoluble framework materials while offering processability advantages. A popular approach to access tailored metal-based motifs in extended network materials is postsynthetic metalation, which allows metal installation to be decoupled from framework assembly. Surprisingly, this approach has only sparingly been reported for molecular porous materials. In this report, we demonstrate postsynthetic metalation of tetrahedral [4 + 4] POCs assembled from tris(2-aminoethyl)amine (TREN) and 1,3,5-tris(4-formylphenyl)benzene. The trigonally symmetric TREN motif is a common chelator in coordination chemistry and, in the POCs explored herein, readily binds copper(I) and silver(I) to form cationic cages bearing discrete mononuclear coordination fragments. Metalation retains cage porosity, allowing us to compare the sorption properties of the parent organic and metalated cages. Interestingly, introduction of copper(I) facilitates activated oxygen chemisorption, demonstrating how targeted metalation can be exploited to tune the sorption characteristics of porous molecular materials.

MOFs with the Stability for Practical Gas Adsorption Applications Require New Design Rules

Metal-organic frameworks (MOFs) have been widely studied for their ability to capture and store greenhouse gases. However, most computational discovery efforts study hypothetical MOFs without consideration of their stability, limiting the practical application of novel materials. We overcome this limitation by screening hypothetical ultrastable MOFs that have predicted high thermal and activation stability, as judged by machine learning (ML) models trained on experimental measures of stability. We enhance this set by computing the bulk modulus as a measure of mechanical stability and filter 1102 mechanically robust hypothetical MOFs from a database of ultrastable MOFs (USMOF DB). Grand Canonical Monte Carlo simulations are then employed to predict the gas adsorption properties of these hypothetical MOFs, alongside a database of experimental MOFs. We identify privileged building blocks that lead MOFs in USMOF DB to show exceptional working capacities compared to the experimental MOFs. We interpret these differences by training ML models on CO2 and CH4 adsorption in these databases, showing how poor model transferability between data sets indicates that novel design rules can be derived from USMOF DB that would not have been gathered through assessment of structurally characterized MOFs. We identify geometric features and node chemistry that will enable the rational design of MOFs with enhanced gas adsorption properties in synthetically realizable MOFs.

A 3D copper (II) coordination polymer based on sulfanilic acid ligand (CP 1) for efficient biomolecular interaction with bovine serum albumin: spectroscopic, molecular modelling and DFT analysis

Several biochemical reactions occur during the interaction of metal complexes and proteins due to conformational modifications in the structure of the protein, which provide fundamental knowledge of the effect, mechanism, and transport of many drugs throughout the body. Here, we report the synthesis, identification, and impact of the 3-dimensional Copper(II)sulfanilic acid coordination polymer (CP 1) on interactions with bovine serum albumin (BSA). The CP 1 was synthesized via a simple hot stirring method, and the single crystal XRD confirms the effective bonding interactions between metal and organic ligand, forming a crystalline polymeric chain and the topological study shows the sql type of underlying net topology. Powder XRD, Fourier transform infrared spectroscopy, and thermogravimetric analysis were also performed. Moreover, DFT/B3LYP calculations provide chemical precision for the resulting complex. Further, the changes that occur in the secondary structure of protein when CP 1 binds with BSA as well as its binding capacity were investigated via circular dichroism analysis and spectroscopic methods such as UV-absorption spectroscopy and fluorescence spectroscopy, respectively. The CP 1/BSA complex melting point was also measured, and its temperature-dependent heat denaturation was studied along with molecular docking.Communicated by Ramaswamy H. Sarma.

A Zr-hydroxamate metal-organic framework with intrinsic chelating sites for postsynthetic Pd metalation and Suzuki-Miyaura catalysis

A highly crystalline and robust Zr-hydroxamate metal-organic framework (MOF) was prepared from a pyrazine-based ligand, featuring abundant N,N' chelating sites. High-degree Pd(II) metalation of the MOF was achieved through straightforward postsynthetic modification, with detailed coordination chemistry elucidated spectroscopically. The Pd-functionalized MOF was then studied as a heterogeneous Suzuki-Miyaura catalyst, through combined experimental/computational methods.

Organic and Metal-Organic Polymer-Based Catalysts-Enfant Terrible Companions or Good Assistants?

This overview provides insights into organic and metal-organic polymer (OMOP) catalysts aimed at processes carried out in the liquid phase. Various types of polymers are discussed, including vinyl (various functional poly(styrene-co-divinylbenzene) and perfluorinated functionalized hydrocarbons, e.g., Nafion), condensation (polyesters, -amides, -anilines, -imides), and additional (polyurethanes, and polyureas, polybenzimidazoles, polyporphyrins), prepared from organometal monomers. Covalent organic frameworks (COFs), metal-organic frameworks (MOFs), and their composites represent a significant class of OMOP catalysts. Following this, the preparation, characterization, and application of dispersed metal catalysts are discussed. Key catalytic processes such as alkylation-used in large-scale applications like the production of alkyl-tert-butyl ether and bisphenol A-as well as reduction, oxidation, and other reactions, are highlighted. The versatile properties of COFs and MOFs, including well-defined nanometer-scale pores, large surface areas, and excellent chemisorption capabilities, make them highly promising for chemical, electrochemical, and photocatalytic applications. Particular emphasis is placed on their potential for CO2 treatment. However, a notable drawback of COF- and MOF-based catalysts is their relatively low stability in both alkaline and acidic environments, as well as their high cost. A special part is devoted to deactivation and the disposal of the used/deactivated catalysts, emphasizing the importance of separating heavy metals from catalysts. The conclusion provides guidance on selecting and developing OMOP-based catalysts.

Topochemical Polymerization at Diacetylene Metal-Organic Framework Thin Films for Tuning Nonlinear Optics

Developing the topochemical polymerization of metal-organic frameworks (MOFs) is of pronounced significance for expanding their functionalities but is still a challenge on third-order nonlinear optics (NLO). Here, we report diacetylene MOF (CAS-1-3) films prepared using a stepwise deposition method and film structural transformation approach, featuring dynamic structural diversity. The MOF structures were determined by the three-dimensional electron diffraction (3D ED) method from nanocrystals collected from the films, which provides a reliable strategy for determining the precise structure of unknown MOF films. We demonstrate the well-aligned diacetylene groups in the MOFs can promote topological polymerization to produce a highly conjugated system under thermal stimulation. As a result, the three MOF films have distinct NLO properties: the CAS-1 film exhibits saturable absorption (SA) while CAS-2 and CAS-3 films exhibit reverse saturable absorption (RSA). Interestingly, due to the topochemical polymerization of the MOF films, a transition from SA to RSA response was observed with increasing temperatures, and the optical limiting effect was significantly enhanced (∼46 times). This study provides a new strategy for preparing NLO materials and thermally regulation of nonlinear optics.

Rise of Metal-Organic Frameworks: From Synthesis to E-Skin and Artificial Intelligence

Metal-organic frameworks (MOFs) have attained broad research attention in the areas of sensors, resistive memories, and optoelectronic synapses on the merits of their intriguing physical and chemical properties. In this review, recent progress on the synthesis of MOFs and their electronic applications is introduced and discussed. Initially, the crystal structures and properties of MOFs encompassing optical, electrical, and chemical properties are discussed in brief. Subsequently, advanced synthesis methods for MOFs are introduced, categorized into hydrothermal approach, microwave synthesis, mechanochemical synthesis, and electrochemical deposition. After that, the various roles of MOFs in widespread applications, including sensing, information storage, optoelectronic synapses, machine learning, and artificial intelligence, are discussed, highlighting their versatility and the innovative solutions they provide to long-standing challenges. Finally, an outlook on remaining challenges and a future perspective for MOFs are proposed.