Recent Advances on the Gas-Sensing Properties and Mechanism of Perovskite Oxide Materials - A Review

Perovskite oxide-based materials (ABO3) have gained much attention as promising candidates for advanced gas-sensing applications due to their versatile structures, tunable properties, and excellent stability. This review discusses recent developments in the synthesis, structural optimization, and functionalization of perovskites to enhance their gas-sensing performance. Strategies such as doping, creating oxygen vacancies, tuning morphology, and forming heterojunctions have significantly improved their sensitivity, selectivity, response, and recovery times. Specific advances include the incorporation of nanostructures, porous morphologies, and catalytic elements, which have optimized the adsorption and desorption processes for various target gases, including volatile organic compounds, NO2, and CO2. Mechanistic insights into the role of oxygen vacancies, surface defects, and charge carrier dynamics are also addressed. These developments position perovskite materials as important components in next-generation gas sensors for environmental monitoring and industrial applications.

Innovative Chemical Strategies for Advanced CRISPR Modulation

ConspectusOver the past decade, RNA-guided gene editing technologies, particularly those derived from CRISPR systems, have revolutionized life sciences and opened unprecedented opportunities for therapeutic innovation. Despite their transformative potential, achieving precise control over the activity and specificity of these molecular tools remains a formidable challenge, requiring advanced and innovative regulatory strategies. We and others have developed new approaches that integrate chemical ingenuity with bioorthogonal techniques to achieve remarkable precision in CRISPR regulation. One key innovation lies in the chemical modulation of guide RNA (gRNA), significantly expanding the CRISPR toolkit. Strategies such as CRISPR-ON and CRISPR-OFF switches rely on selective chemical masking and demasking of gRNA. These approaches use either bulky chemical groups to preemptively mask RNA or minor, less obstructive groups to fine-tune its function, followed by bioorthogonal reactions to restore or suppress activity. These methodologies have proven to be pivotal for controlled gene editing and expression, addressing the challenges of precision, reversibility, and dynamic regulation.Parallel to these advances, the development of mesoporous metal-organic frameworks (MOFs) has emerged as a promising solution for RNA deprotection and activation. By serving as catalytic tools, MOFs enhance the versatility and efficiency of CRISPR systems, pushing their applications beyond the conventional boundaries. In addition, the synthesis of novel small molecules for regulating CRISPR-Cas9 activity marks a critical milestone in the evolution of gene therapy protocols. Innovative RNA structural control strategies have also emerged, particularly through the engineering of G-quadruplex (G4) motifs and G-G mismatches. These methods exploit the structural propensities of engineered gRNAs, employing small-molecule ligands to induce specific conformational changes that modulate the CRISPR activity. Whether stabilizing G4 formation or promoting G-G mismatches, these strategies demonstrate the precision and sophistication required for the molecular-level control of gene editing.Further enhancing these innovations, techniques like host-guest chemistry and conditional diacylation cross-linking have been developed to directly alter gRNA structure and function. These approaches provide nuanced, reversible, and safe control over CRISPR systems, advancing both the precision and reliability of gene editing technologies. In conclusion, this body of work highlights the convergence of chemistry, materials science, and molecular biology to create integrative solutions for gene editing. By combination of bioorthogonal chemistry, RNA engineering, and advanced materials, these advancements offer unprecedented accuracy and control for both fundamental research and therapeutic applications. These innovations not only advance genetic research but also contribute to developing safer and more effective gene editing strategies, moving us closer to realizing the full potential of these technologies.

In situ generated hydrogen-bonding microenvironment in functionalized MOF nanosheets for enhanced CO2 electroreduction

The microenvironment around catalytic sites plays crucial roles in enzymatic catalysis while its precise control in heterogeneous catalysts remains challenging. Herein, the coordinatively unsaturated metal nodes of Hf-based metal-organic framework nanosheets are simultaneously codecorated with catalytically active Co(salen) units and adjacent pyridyl-substituted alkyl carboxylic acids via a post modification route. By varying pyridyl-substituted alkyl carboxylic acids, the spatial positioning of the N atom in pyridine group relative to adjacent Co(salen) can be precisely controlled. Notably, the 3-(pyridin-4-yl)propionic acid, with para-position pyridine N atom, maximally improves the electrocatalytic CO2 reduction performance of Co(salen) unit, far superior to other counterparts. Mechanism investigations reveal that the pyridine unit of 3-(pyridin-4-yl)propionic acid is optimally positioned relative to Co(salen) and undergoes in situ reduction to pyridinyl radical under working potentials. This greatly facilitates the stabilization of *COOH intermediate via hydrogen-bonding interaction, lowering the formation energy barrier of *COOH and therefore boosting CO2 electroreduction.

Metal pyrazolate frameworks: crystal engineering access to stable functional materials

As the focus evolves from structure discovery/characterization (what it is) to property/performance exploration (what it is for), the pursuit of stable functional metal-organic frameworks (MOFs) has been ongoing in terms of both fundamental research and industrial implementation. Under the guidance of crystal engineering principles, a plethora of research has developed pyrazolate MOFs (metal pyrazaolate frameworks, MPFs) featuring strong coordination M-N bonding. This attribution helps them retain their structures and functions under the alkaline conditions required for practical use. Based on poly-topic pyrazolate ligands, various classic MOFs, such as Co(bdp), Fe2(BDP)3, Ni8L6, PCN-601, and BUT-55, to name a few, have revealed fascinating architectures, intriguing properties, and record-breaking performances in applications during the past decade. This review will present the full scope of MPFs to date: (1) the superiority and significance of constructing MPFs through the crystal engineering approach, (2) synthetic strategies adopted in building and/or modifying MPFs, (3) structural features and stability of the MPF community, and (4) potential applications in energy and environmental related fields. The future opportunities of MPFs are also discussed for designing the next-generation of smart materials. Overall, this review attempts to provide insights and guidelines for the customization of pyrazolate-based MOFs for specific purposes, which would also promote the development of stable functional porous materials for addressing societal challenges.

Benchmark Paraffin Adsorption in a Super-Hydrophobic Porous Coordination Polymer with Blade-Like Circular Phenyl Nanotraps

Selective capture of paraffin from olefin that permits one-step purification of olefin is significantly important, yet developing adsorbents with high selectivity and hydrophobicity remains a daunting challenge. Although aromatic environments can enhance paraffin affinity and hydrophobicity through nonpolar interactions, water adsorption still occurs in regions distant from the aromatic rings, as well as in secondary pores that are always overlooked. Herein, we reported an ultramicroporous porous coordination polymer (ZnFPCP) featuring blade-like circular phenyl paraffin nanotraps. As further validated by density functional tight binding (DFTB) calculations, grand canonical Monte Carlo (GCMC) simulations, and in situ Fourier-tansform infrared absorption (FT-IR) analysis, these ultramicroporous paraffin nanotraps created by surrounding benzene rings enhance the paraffin-selective adsorption, and the segmented spaces between adjacent nanotraps in the blade-like structure, combined with hydrophobic petal-like secondary pore channels enclosed by fluorinated functional groups, further mitigate the water co-adsorption. Remarkably, ZnFPCP exhibited outstanding ideal adsorption solution theory (IAST) selectivity (C3H8/C3H6: 2.08, C2H6/C2H4: 2.93) under ambient conditions and record-breaking C3H8/C2H6 uptake at low pressures. Breakthrough experiments demonstrated the excellent performance of ZnFPCP in olefin purification, affording the exceptional productivity of ultra-high purity (99.99%) for C3H6 and C2H4. Robust stability and super hydrophobicity highlight its potential in harsh industrial application scenarios.

Assessing UFF and DFT-Tuned Force Fields for Predicting Experimental Isotherms of MOFs

Metal-organic frameworks (MOFs) are promising materials for gas storage and separation applications due to their high tunability and porosity. The rational design of MOFs relies on accurate computational modeling, with grand canonical Monte Carlo (GCMC) simulations frequently employed to model gas uptake. However, GCMC predictions often deviate from experimental observations, limiting their utility in MOF screening. These discrepancies primarily arise from three factors: inaccuracies in the force field, neglect of atomic motions, and neglect of structural imperfections in MOFs. In this study, we systematically evaluate the impact of the first factor on the predictive accuracy of the GCMC simulations. We evaluate the widely used Universal Force Field (UFF) by comparing its predictions with experimental isotherms for four representative adsorbates, H2, CO2, C2H4, and C2H6, across 379 isotherms from 142 MOFs. The results show that UFF consistently overestimates the gas uptake in GCMC simulations. To isolate the contribution of force field inaccuracies to errors in GCMC, we developed a practical scheme for fitting force field parameters to DFT-calculated energies for a large set of MOFs. While the refined force field improves the accuracy of interatomic interaction energies, its reduction of repulsion, combined with UFF's tendency to overestimate gas uptake, ultimately amplifies the overestimation of experimental gas uptake meaurement. Our analysis suggests that improving the agreement of gas adsorption prediction with experiments requires addressing atomic motion and structural defects in MOFs alongside force field refinements.

Zirconium Metal-Organic Frameworks as Micromotors with Enzyme-like Activity for Glutathione Detection

Herein, we report a novel UiO-67-Co(bpy)0.35 micromotor synthesized by a facile postsynthesis metalation via introducing cobalt salts ligated with 2,2'-bipyridine-5,5'dicarboxylic acid into UiO-67-bpy0.35 framework. The Co2+ active sites can decompose H2O2 to generate bubbles to power UiO-67-Co(bpy)0.35. Meanwhile, the UiO-67-Co(bpy)0.35 micromotor exhibits robust peroxidase-like activity through catalyzing H2O2 to generate •OH under neutral conditions. Based on this, a sensing platform was constructed for the colorimetric detection of GSH. Due to the synergy of self-driven motion and excellent peroxide-like activity, UiO-67-Co(bpy)0.35 micromotor can sensitively detect GSH with a low analytic limitation as 0.13 μM for GSH detection. This study provides a new sight of using the postsynthesis metalation method to prepare Zr(Co)-MOF micromotor for highly selective, sensitive, and facile detection of GSH.

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.

Silver Nanoparticles Decorated UiO-66-NH2 Metal-Organic Framework for Combination Therapy in Cancer Treatment

Background: Nanomedicine has shown significant promise in advancing cancer diagnostics and therapeutics. In particular, nanoparticles (NPs) offer potential for overcoming limitations associated with conventional therapies, such as off-target toxicity and side effects. Among the various NPs, silver nanoparticles (AgNPs) have garnered attention due to their cytotoxic and genotoxic properties in cancer cells. However, despite their potential, the optimization of AgNPs efficacy often necessitates combination strategies with other therapeutic agents. This study explores the potential of AgNPs integrated with Zr-based metal-organic frameworks (MOFs) UiO-66 for drug delivery, to enhance cancer therapy. Methods: We decorated amino-terephthalic based UiO-66-NH2 with AgNPs and loaded it with the chemotherapeutic agent cisplatin (Cis-Pt) to make the UiO-66-NH2@AgNPs@Cis-Pt. A preliminary MTT assay was conducted to evaluate the cytotoxic effects of the nanocomposite on several glioblastoma and other tumour cell lines, including U251, U87, GL261, HeLa, RKO, and HepG2. Results: Our results demonstrate that UiO-66-NH2@AgNPs@Cis-Pt and its combinations exhibit enhanced cytotoxicity compared to individual components such as AgNPs and Cis-Pt. Conclusions: This work offers preliminary insights into the potential of AgNP-functionalized MOFs as effective drug and delivery platforms, particularly in the context of combination therapy for cancer treatment.

Tuning the Pore Microenvironment of Metal-Organic Frameworks for Boosting CO2 Fixation

The pore microenvironment plays an important role in catalytic systems, as it can regulate substrate transport, reactant molecule enrichment, and the strength of active centers, thereby affecting catalytic performance. However, the effect of pore sizes/functionality/Lewis acid strength on catalytic performance has still not been adequately and systematically investigated and summarized. Herein, a series of isostructural fcu-type metal-organic frameworks (MOFs) are used through a novel strategy to study the effect of subtle changes in pore microenvironment on the catalysis of carbon dioxide (CO2) cycloaddition at ambient temperature and pressure. The results of systematic experiments indicate that the enlargement of the pore size of MOFs, the access of pore wall functional groups, and the increase of Lewis acid strength of metal nodes can significantly improve the performance of the CO2 cycloaddition reaction. The reaction mechanism catalyzed by fcu-type MOFs is investigated in detail, based on the experimental inferences and periodic calculations of density functional theory. This study provides a reference for designing of high-performance catalysts for CO2 fixation.

Three-Dimensional Metal-Organic Frameworks with Selectively Activated Aromatic Rings for High-Capacity and High-Rate Lithium-Ion Storage

Metal-organic frameworks (MOFs) are considered promising candidates for anode materials in Li-ion batteries (LIBs) owing to their designable structure, abundant active sites, and well-organized porosity. However, the structural factors governing active site utilization and Li-ion storage kinetics remain inadequately understood. In particular, the Li-ion storage behaviors of aromatic rings with high LUMO energy levels and situated in varying chemical environments remain a highly debated issue. Herein, a new cobalt-based MOF (Co-NTTA, NTTA ligand: 5,5',5''-((4,4',4''-nitrilotris (benzoyl)) tris-(azanediyl)) triisophthalic acid), featuring aromatic rings situated in diverse local environments, is deliberately designed and synthesized. Experimental characterizations and first-principles calculations have verified the occurrence of a reversible electrochemical reaction involving a total of 51 electrons among the NTTA ligands, cobalt cations, and Li+ ions. Unlike the traditional concept of superlithiation, the three inner aromatic rings are selectively activated by π-aromatic conjugation networks and π ⋯ ${\cdots }$ π stacking, contributing to a reversible 6-electron pseudocapacitive Li+ intercalation reaction. Conversely, the three outer aromatic rings remain inert toward Li+ ions. Impressively, the Co-NTTA MOF anode, with selectively activated aromatic rings, delivers a reversible capacity of up to 956 mAh g-1 at 200 mA g-1 and demonstrates exceptional high-rate durability, further supporting a 4.3 V lithium-ion hybrid electrochemical capacitor with high energy/power density.

Engineered Metal-Organic Frameworks for Targeted CRISPR/Cas9 Gene Editing

The development of precise and efficient delivery systems is pivotal for advancing CRISPR/Cas9 gene-editing technologies, particularly for therapeutic applications. Engineered metal-organic frameworks (MOFs) have emerged as a promising class of inorganic nonviral vectors, offering unique advantages such as tunable porosity, high cargo-loading capacity, and biocompatibility. This review explores the design and application of MOF-based nanoplatforms tailored for the targeted delivery of CRISPR/Cas9 components, aiming to enhance gene-editing precision and efficiency. By incorporating stimuli-responsive linkers and bioactive ligands, these MOFs enable controlled release of CRISPR/Cas9 payloads at the target site. Comparative discussions demonstrate superior performance of MOFs over conventional nonviral systems in terms of stability, transfection efficiency, and reduced off-target effects. Additionally, the intracellular trafficking mechanisms and the therapeutic potential of these platforms in preclinical models are discussed. These findings highlight the transformative potential of MOF-based delivery systems in overcoming the challenges associated with gene-editing technologies, such as immunogenicity and cytotoxicity, paving the way for their application in precision medicine. This review provides a blueprint for the integration of nanotechnology and genome editing, advancing the frontier of nonviral therapeutic delivery systems.

Open tubular column coated with a novel zinc-based MOF/imine COF hybrid, for small molecular separation using capillary electrochromatography

Metal organic frameworks (MOFs) and covalent organic frameworks (COFs) represent two burgeoning categories of advanced porous materials that have garnered substantial interest within the scientific community in recent years. Notably, the synergistic effect of MOFs and COFs facilitates their integration into MOF/COF hybrid structures, thereby enhancing performance and broadening their applicability across diverse fields. Herein, we report the development of a novel capillary electrochromatographic coated open tubular column, utilizing a MOF/COF hybrid material (ZIF-93/TpBD) as the stationary phase, to achieve high-resolution separation of six groups of analogues. Both ZIF-93/TpBD-coated open tubular (OT) column and the hybrid stationary phase were characterized using a series of analytical techniques. The outstanding separation performance of the as-prepared OT column was evaluated using alkaline amino acids, sulfonamides, acidic antibiotics, vitamin B, purine compounds and β-blocker analyte groups, under optimal separation conditions. The six groups of analytes achieved baseline separation within 9.5 minutes and achieved high resolution (ranging from 1.50 to 9.71). Furthermore, the run to run, day to day, column to column and batch to batch relative standard deviations of retention time and column efficiency were in the range 0.71-3.91% and 0.49-4.19%, respectively. The ZIF-93/TpBD-coated OT column exhibited remarkable stability after 200 consecutive runs. Finally, a rapid, highly efficient, accurate, and reliable method was developed for the qualitative and quantitative analysis of vitamins B1, B2, B6 and nicotinamide in healthcare settings. This novel hybrid stationary phase, composed of MOF/COF, presents a new avenue for the advancement of chromatographic separation.

Chemoselective Hydrogenation of Halonitrobenzenes by Platinum Nanoparticles with Auxiliary Co-N4 Single Sites in Sandwiched Catalysts

The chemoselective hydrogenation of halonitrobenzenes to haloanilines is of great importance but remains challenging to simultaneously achieve high catalytic activity, excellent selectivity, and good reusability, especially for ortho-substituted substrates. This is due to the occurrence of hydrogenolysis of halogen groups, as well as the easy migration and aggregation of active species on the catalyst surface during the hydrogenation of nitro groups. In this study, we integrate Pt nanoparticles (NPs) with auxiliary Co-N4 single sites from a porphyrinic metal-organic framework [known as PCN-221(Co)] in a sandwiched nanostructure as a catalyst for the chemoselective hydrogenation of ortho-halonitrobenzenes at 80 °C and 1 MPa H2 in a 50 mL batch microreactor. This sandwiched catalyst achieves 97.3% selectivity for ortho-chloroaniline at nearly complete conversion of ortho-chloronitrobenzene, with an exceptionally high turnover frequency (TOF) of 11,625 h-1 and good reusability over ten cycles, outperforming state-of-the-art heterogeneous supported metal catalysts. Theoretical and experimental investigations reveal that the nitro group in ortho-chloronitrobenzene is preferentially hydrogenated by Pt NPs, while the ortho-chloro group is selectively adsorbed by Co-N4 single sites in PCN-221(Co), preventing its hydrogenolysis and enhancing selectivity for ortho-chloroaniline. Furthermore, the PCN-221(Co) shell in the sandwiched catalyst plays a key role in enriching ortho-chloronitrobenzene and stabilizing the supported Pt NPs, thus leading to high catalytic activity and good reusability. Additionally, at nearly complete conversion of ortho-fluoronitrobenzene and ortho-bromonitrobenzene, this sandwiched Pt catalyst displays 100% selectivity for ortho-fluoroaniline with a TOF of 8680 h-1 and 99.2% selectivity for ortho-bromoaniline with a TOF of 5859 h-1, respectively. When meta- and para-halonitrobenzenes are used as substrates, high activity and excellent selectivity for the corresponding haloanilines are also achieved by the sandwiched Pt catalysts.

Theoretical Calculations in Separation Science for Analytical Chemistry: Applications and Insights

Separation and enrichment are critical steps in analytical detection, necessitating advanced materials with high selectivity and adsorption capacity for target compounds. In order to improve separation efficiency and selectivity, computational simulation could elucidate interaction mechanisms and analyze potential adsorption/desorption processes, providing a theoretical foundation for the optimization and design of separation materials. Recently, computational simulation has become an indispensable and crucial mean in separation science for analytical chemistry. Using various simulation software, researchers could investigate the structures, properties, and performance of separation materials at multiple levels and scales. In this review, we summarize the applications of computational simulations in the field of separation science, focusing on the separation of polar molecules, geometric isomers, enantiomer compounds, and post-translationally modified peptides. These calculation methods include quantum chemistry, molecular docking, molecular dynamics simulations, high-throughput screening, and machine learning. Finally, we discuss the current challenges and potential breakthroughs in computational simulation, aiming to offer valuable insights for researchers dedicated to computational simulation, material development, and separation applications.

Microscopic Kinetics of Water Adsorption in Metal-Organic Frameworks

Metal-organic frameworks (MOFs) have shown great potential in atmospheric water harvesting, dehumidification, and passive evaporative cooling. Their performance is determined by the water uptake and adsorption kinetics of the MOFs. Here, the water adsorption kinetics in MOFs are systematically investigated using our proposed theoretical framework and experimental measurements. At low relative humidities (RHs), water molecules are adsorbed and diffuse freely in MOFs, as described by the linear driving force assumption and Fick's law. At high RHs, water condenses into liquid clusters before diffusing, modeled by a two-concentration framework. At medium RHs, both water molecules and clusters coexist in MOFs. Good agreement between experiments and simulations of water uptake and kinetics of UiO-66, CAU-10-H, MOF-801, MIL-101, and MOF-303 demonstrates our theoretical framework fully captures water vapor adsorption processes in MOFs. Our results further show that water adsorption capacity and kinetics are jointly influenced by the porosity, pore radius, and pore geometry factor.

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.

Target-Triggered Cascaded Self-Feedback DNAzyme Circuit Loaded in ZIF-8 for Highly Sensitive miRNA Imaging in Living Cells

The highly sensitive and rapid imaging of miRNA in living cells promises to advance our understanding of diseases and promote their diagnosis and treatment. To enhance the sensitivity of miRNA imaging, a series of cascade signal amplification strategies based on enzyme-free methods have been developed. However, these cascaded amplification strategies involve complex designs and multiple amplification mechanisms, leading to potential side effects. Herein, we have developed a novel hairpins@ZIF-8 nanosystem by rationally integrating ZIF-8 with a cascaded self-feedback DNAzyme circuit (CSDC), achieving highly sensitive and rapid imaging of miRNA in living cells. ZIF-8 facilitates the efficient transfection of nucleic acid probes into cells and provides the necessary cofactor ions for CSDC. The developed CSDC possesses exponential amplification based solely on the DNAzyme mechanism. Benefiting from the exponential amplification efficiency, the CSDC exhibited higher sensitivity than traditional DNAzyme-based amplification, with a detection limit of 2.28 fM, approximately 105 times more sensitive than traditional DNAzyme-based amplification. This hairpins@ZIF-8 nanosystem demonstrated strong practical application capabilities, effectively reflecting fluctuations in intracellular miRNA levels and successfully distinguishing between normal and tumor cells based on miRNA expression differences. It could also be applied for in vivo miRNA imaging. This proposed strategy is anticipated to pave the way for innovative amplification approaches and serve as a vital instrument in miRNA-related research, diagnosis, and treatment.

Topological Supramolecular Complexation of Metal-Organic Polyhedra for Tunable Interconnected Hierarchical Microporosity in Amorphous Form

The precise engineering of microporosity is challenging due to the interference at the sub-nm scale from unexpected structural flexibility and molecular packing. Herein, the concept of topological supramolecular complexation is proposed for the feasible fabrication of hierarchical microporosity with broad tunability in amorphous form. The 2.5 nm metal-organic polyhedra (MOP) are complexed with quadridentate ligands through hydrogen and coordination bonding while the mismatch between the MOPs' cuboctahedron and ligands' tetrahedron topology leads to frustrated packing with extrinsic microporosity. Amorphous supramolecular frameworks can be obtained that integrate the intrinsic microporosity of the MOPs with the extrinsic porosity from the frustrated packing. The topologies, sizes and flexibility of ligands as well as ligand/MOP ratios are systemically varied, and the pore size distribution can be precisely adjusted. The hierarchical structures ranging from molecular packing to the morphologies of meso-scale assemblies are probed using ultra-small, small- and wide-angle X-ray scattering, enabling the quantitative evaluation of the micropores interconnectivity for the understanding of gas permeation performance. Gas separation membranes with permselectivity surpassing the Robeson upper bound can be designed. The findings not only give insight into the microscopic mechanism of supramolecular frustrated packing from topological design, but also pave new avenues for the cost-effective fabrications of microporous frameworks.

Stable Interpenetrated Zirconium-Based Metal-Organic Framework for the Fluorescence Detection of MnO4. Inorg Chem 2025;64:6648-6655. [PMID: 40128184 DOI: 10.1021/acs.inorgchem.5c00200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

In this work, a novel stable zirconium-based metal-organic framework (Zr-MOF) with the formula [Zr6O4(OH)4(PVDC)6]4·66DMF (Zr-1, H2PVDC = (E,E)-2,5-dimethoxy-1,4-bis[2-(4-carboxylatestyryl)]benzene; DMF = N,N-dimethylformamide) was synthesized by introducing a linear phenylenevinylene-based carboxylate ligand to react with ZrCl4 under solvothermal conditions. According to single-crystal X-ray diffraction measurement, complex Zr-1 featured a 2-fold interpenetrated framework, in which the single coordination framework possessed a structure similar to that of the well-known Zr-MOF, UiO-66, constructed from [Zr6O4(OH)4]12+ clusters and carboxylate ligands PVDC2-. Due to the introduction of the phenylenevinylene-functionalized ligand, complex Zr-1 exhibited a unique fluorescence sensing performance toward permanganate (MnO4-) with different concentrations. At low concentrations, the fluorescence emission intensity of Zr-1 around 510 nm was enhanced significantly with an increase in the concentration of MnO4- in an aqueous suspension. However, while excess MnO4- was added into the suspension, the fluorescence emission intensity decreased significantly, and the single emission peak turned into five emission peaks upon the addition of MnO4-. Such a phenomenon has been scarcely reported in previous MOF-based fluorescence sensors. Moreover, complex Zr-1 showed high anti-interference capability for the detection of MnO4- both at low and high concentrations. This work may pave a new way for the development of MOF-based fluorescence sensing platforms.

Dimensionality Reduction of Metal-Organic Frameworks to Monolayers for Enhanced Electrocatalysis

Metal-organic frameworks (MOFs) are potential candidates for electrocatalysis due to their well-defined, tunable structures, and ability to incorporate diverse active sites. However, their inherent insulating nature restricts electron transfer from electrode to remote active sites, leading to diminished catalytic performance. In this work, we present a novel strategy to overcome this limitation by reducing 3D MOFs (3D_MOFs) into monolayered MOFs (monoMOFs) with a thickness of ∼1.8 nm, maximizing the exposure of catalytic sites to the electrode and enhancing electrocatalytic performance. We designed and synthesized a monoMOF incorporating cobalt(II)-porphyrin sites in the linker (monoMOF-Co) for CO2 electroreduction. After being grafted onto graphene oxide, the monoMOF-Co exhibited a peak faradaic efficiency for CO production (FECO = 93%), surpassing the performance of a 3D_MOF incorporating the same porphyrin-Co-based linker (3D_MOF-Co, FECO = 51%). Additionally, monoMOF-Co achieved a turnover frequency of 10 600 h-1 at -0.8 V versus the reversible hydrogen electrode (RHE) and maintained stability over 47 h in a near-neutral aqueous solution. In situ spectroscopic studies further confirmed the distinct electric field environment in the Stern layer between monoMOF-Co and 3D_MOF-Co. Furthermore, similar enhancement effects of monoMOFs over 3D_MOFs were observed in the nitrate and oxygen electroreduction reactions, highlighting the broader applicability of monoMOFs in electrocatalysis.

Engineering Bodipy-Based Metal-Organic Frameworks for Efficient Full-Spectrum Photocatalysis in Amide Synthesis

Developing photocatalysts that can efficiently utilize the full solar spectrum is a crucial step toward transforming sustainable energy solutions. Due to their light absorption limitations, most photo-responsive metal-organic frameworks (MOFs) are constrained to the ultraviolet (UV) and blue light regions. Expanding their absorption to encompass the entire solar spectrum would unlock their full potential, greatly enhancing efficiency and applicability. Here, we report the design and synthesis of a series of highly stable boron-dipyrromethene (bodipy)-based MOFs (BMOFs) by reacting dicarboxyl-functionalized bodipy ligands with Zr-oxo clusters. Leveraging the acidity of the methyl groups on the bodipy backbone, we expanded the conjugation system through a solid-state condensation reaction with various aldehydes, achieving full-color absorption, thereby extending the band edge into the near-infrared (NIR) and infrared (IR) regions. These BMOFs demonstrated exceptional reactivity and recyclability in heterogeneous photocatalytic activities, including C─H bond activation of saturated aza-heterocycles and C─N bond cleavage of N,N-dimethylanilines to produce amides under visible light. Our findings highlight the transformative potential of BMOFs in photocatalysis, marking a significant leap forward in the design of advanced photocatalytic materials with tunable properties.

Hydroxyl-induced structural defects in metal-organic frameworks for improved photocatalytic decontamination: Accelerated exciton dissociation and hydrogen bonding interaction

The introduction of structural defects can improve the charge separation efficiency of metal-organic frameworks (MOFs)-based photocatalysts, which however come with suboptimal decontamination performance, due to steric hindrance and limited binding capacity of the involved modulators. In this work, hydroxyl group capturing the advantages of both worlds was utilized as new modulator to improve the photocatalytic performance of Fe-based defective MOFs. Benefited from its low steric effect and strong coordination bonding capability, hydroxyl-induced defects in Fe-MOF contributed to a nearly 8-fold increase of rate constant for the photocatalytic removal of hexavalent chromium (Cr(VI)) compared to that of pristine one, which also exceeded the defective one induced by acetic acid as modulator. A combination of characterizations and theoretical calculations suggests that hydroxyl-induced structural defects fostered faster kinetics of exciton dissociation and optimal charge separation. The higher electron utilization through hydrogen bonding interaction between these hydroxyl-induced structural defects and contaminant was further confirmed by ab initio molecular dynamics (AIMD) simulations. This work presents a simple yet robust strategy for the generation of defective MOFs, upon which efficient photoreduction systems toward Cr(VI) removal are anticipated.

Selective adsorption of CO2 in TAMOF-1 for the separation of CO2/CH4 gas mixtures

TAMOF-1 is a robust, highly porous metal-organic framework built from Cu2+ centers linked by a L-histidine derivative. Thanks to its high porosity and homochirality, TAMOF-1 has shown interesting molecular recognition properties, being able to resolve racemic mixtures of small organic molecules in gas and liquid phases. Now, we have discovered that TAMOF-1 also offers a competitive performance as solid adsorbent for CO2 physisorption, offering promising CO2 adsorption capacity ( > 3.8 mmol g-1) and CO2/CH4 Ideal Adsorbed Solution Theory (IAST) selectivity ( > 40) at ambient conditions. Moreover, the material exhibits favorable adsorption kinetics under dynamic conditions, demonstrating good stability in high-humidity environments and minimal degradation in strongly acidic media. We have identified the key interactions of CO2 within the TAMOF-1 framework by a combination of structural (neutron diffraction), spectroscopic and theoretical analyses which conclude a dual-site adsorption mechanism with the majority of adsorbed CO2 molecules occupying the empty voids in the TAMOF-1 channels without strong, directional supramolecular interactions. This very weak dominant binding opens the possibility of a low energy regeneration process for convenient CO2 purification. These features identify TAMOF-1 as a viable solid-state adsorbent for the realization of affordable biogas upgrading.

Enhanced the Trans-Cleavage Activity of CRISPR-Cas12a Using Metal-Organic Frameworks as Stimulants for Efficient Electrochemical Sensing of Circulating Tumor DNA

Continued development of clustered regularly interspaced short palindromic repeats (CRISPR)-powered biosensing system on the electrochemical interface is vital for accurate and timely diagnosis in clinical practice. Herein, an electrochemical biosensor based on manganese metal-organic frameworks (MOFs)-enhanced CRISPR (MME-CRISPR) is proposed that enables the efficient detection of circulating tumor DNA (ctDNA). In this design, customized enzyme stimulants (Mn2+) are co-assembled with Cas12a/crRNA to form enzyme-MOF composites, which can be released quickly under mild conditions. The MOFs-induced proximity effect can continuously provide adequate Mn2+ to sufficiently interact with Cas12a/crRNA during the release process, enhancing the trans-cleavage activity of complex available for biosensor construction. The MOFs-based enzyme biocomposites also afford efficient protection against various external stimulus. It is demonstrated that the developed biosensor can achieve ultrasensitive detection of epidermal growth factor receptor L858R mutation in ctDNA with a low detection limit of 0.28 fm without pre-amplification. Furthermore, the engineered mismatch crRNA enables the biosensor based on MME-CRISPR to detect single nucleotide variant with a high signal-to-noise ratio. More importantly, it has been successfully used to detect the targets in clinical practice, requiring low-dose samples and a short time. This strategy is believed to shed new light on the applications of cancer diagnosis, treatment, and surveillance.

A Capping-assisted Strategy for Synthesis of Glass-like Carboxylate-biased Coordination Polymers

The direct preparation of glass-like carboxylate-based coordination polymers (CPs) possessing continuous internal structure and transparency is challenging due to the lack of control on coordination kinetics and subsequently the range of order. Herein, a capping-assisted strategy was presented to control the molecular assembly during the metal-ligand coordination in the solution and to inhibit the long-range of order hence building glass-like CPs (g-CPs) mimicking the polymerization process. 1,3,5-benzene tricarboxylate (BTC) ligand was used to connect the copper cations (Cu2+) into metal-organic complexes of different Cu: BTC ratios (metal-organic pool) in presence of an excess of triethyl amine as a capping agent. Concentrating the Cu-BTC complexes and further drying under mild conditions induced the decapping process which triggered the random crosslinking between the free carboxylate and Cu2+ to form a boundary-free continuous internal structure. The as-prepared Cu-BTC g-CP exhibited an approximately similar fine structure like its crystalline counterpart (HKUST-1), which facilitated solvent and thermal-induced crystallization. Due to the internal structure continuity, the g-CP possesses ceramic-like hardness and wear resistance and plastic-like resilience. This capping-assisted strategy has been successfully extended to Ni-BTC and Fe-BTC systems under mild conditions and thus presenting a general method for the formation of glass-like carboxylate-based CPs.

Advances in crystalline metal-organic photochromic materials

Metal-organic materials have undergone rapid advancements due to their unique structural properties and exceptional application potential. As a key branch, crystalline metal-organic photochromic materials (CMOPMs), have attracted significant attention for their ability to modulate physical properties in response to light stimulation, thereby expanding the research landscape of metal-organic materials in areas such as molecular switch, gas adsorption and separation, and sensing applications. Furthermore, light as a renewable and clean energy source significantly enhances its application potential. In this feature article, we review the design and synthesis strategies, classification, and applications of CMOPMs. Finally, we present the opportunities and challenges for the development of CMOPMs.

Examining proton conductivity of metal-organic frameworks by means of machine learning

The tunable structure of metal-organic frameworks (MOFs) is an ideal platform to meet contradictory requirements for proton exchange membranes: a key component of fuel cells. Nonetheless, rational design of proton-conducting MOFs remains a challenge owing to the intricate structure-property relationships that govern the target performance. In the present study, the modeling of quantities available for hundreds of MOFs was scaled up to many thousands of entities using supervised machine learning. The experimental dataset was curated to train multimodal transformer-based networks, which integrated crystal-graph, energy grid, and global-state embeddings. Uncertainty-aware models revealed superprotonic conductors among synthesized MOFs that have not been previously investigated for the application in question, thus highlighting magnesium-containing frameworks with aliphatic linkers as high-confidence candidates for experimental validation. Furthermore, classifiers trained on the activation energy threshold effectively discriminated between well-known proton conduction mechanisms, thereby providing physical insights beyond the black-box routine. Thus, our findings prove high potential of data-driven materials design, which is becoming a valuable addition to experimental studies on proton-conducting MOFs.

Pushing Limits of Ultra-wideline Solid-State NMR Spectroscopy: NMR Signatures of 209Bi and 127I in Metal-Organic Frameworks at Ultra-high Magnetic Fields

Bismuth- and iodine-containing metal-organic frameworks (MOFs) are crucial in catalysis, gas adsorption, and luminescence, with local environments of Bi and I ions shaping their performance. Using 209Bi and 127I solid-state NMR (SSNMR) for characterization is extremely challenging due to the exceedingly large quadrupolar interactions in MOFs. Here, we present ultra-wideline (UW) SSNMR spectra of eight MOFs acquired at ultra-high magnetic fields up to 36 T, with breadths of 8-50 MHz, revealing very large quadrupolar couplings. These spectra uncover key structural details, including dehydration, guest adsorption, phase transitions, and disorder. This study establishes 209Bi and 127I UW SSNMR as powerful tools for probing Bi and I ions in weight-dilute systems, offering broad applications in catalysis, solar cells, biochemistry, and beyond.

Unlocking Advanced Architectures of Single-Crystal Metal-Organic Frameworks

The synthesis of metal-organic frameworks (MOFs) with diverse geometries has captivated considerable interest due to their manifestation of novel and extraordinary properties. While much progress has been made in shaping regular polyhedral single-crystal MOFs, the creation of more complex, topologically intricate nanostructures remains a largely unexplored frontier. Here, we present a refined site-specific anisotropic assembly and etching co-mediation approach to fabricate a series of hierarchical MOF nanohybrids and single-crystal MOFs. This approach yields ZIF-8&mSiO2 nanohybrids with diverse topologies, alongside derived single-crystal MOF nanoparticles exhibiting intricate morphologies such as hexapods, nested nanocages, and octopods. Our method involves the selective growth of six mSiO2 nanoplates on the {100} facets of ZIF-8 nanocubes, forming the cubic-shaped ZIF-8&mSiO2 nanohybrids, with the concurrent etching of the {110} facets of initial ZIF-8 nanocubes. By fine-tuning this balance between the growth and etching, we achieved precise morphological control, transforming cubic nanohybrids into intricate hexapods nanohybrids. Additionally, secondary epitaxial growth of homo- or hetero-MOFs on these hybrids led to ZIF-8&mSiO2&MOF composites with six mSiO2 inlays. Finally, selective alkaline etching of the mSiO2 compartments result in single-crystal MOF nanoparticles with unprecedented and sophisticated morphologies, such as hexapods, nested nanocages, octopods. This work advances the field of MOF nanostructure design, opening new avenues for the development of sophisticated, multifunctional materials.

Supramolecular Interpenetrated Faujasite-Like Crystals from [4+4] Imine Cages

In recent years, porous organic cages have gained in importance, inter alia, due to their ability to be processed from solution. Especially the packing of the cages in the solid state has a significant effect on the porosity. Therefore, it is important to be able to control the packing pattern either by crystallization conditions or the interaction of molecular units, defined as crystal engineering synthons. Here, tribromoarene subunits as such are incorporated into cage structures, namely a [2+3] and a [4+4] imine cage, to study the reliability of this subunit as crystal engineering synthon. Several solvatomorphs of both cages were studied by single-crystal X-ray diffraction and packing patterns thoroughly analyzed. Among those solvatomorphs an interpenetrated Faujasite-type supramolecular arrangement is found.

Advances in the development of N-glycopeptide enrichment materials based on hydrophilic interaction chromatography

Protein glycosylation is one of the most important post-translational modifications, implicated in the development of various diseases, including neurodegenerative diseases, diabetes, and cancers. However, the low content of glycoproteins in biological samples, the diversity and heterogeneity of glycan structures, and insensitive detection methods make glycosylation analysis challenging. As a result, efficient enrichment of glycopeptides from complex samples is a critical step. Efficient enrichment technology can increase the abundance of intact N-glycopeptides in complex biological samples, thereby improving the sensitivity and coverage of glycosylation analysis, which is of great significance for the accurate identification of biomarkers and the development of glycopeptide-based drugs. Among various separation methods for N-glycopeptides, hydrophilic interaction chromatography has received increasing attention, and a variety of enrichment materials have been developed. This article classifies and describes the relevant hydrophilic interaction chromatography materials and provides a comprehensive review of their applications in N-glycopeptide enrichment regarding selectivity, sensitivity, and enrichment performance. Future development trends of ideal glycopeptide enrichment materials are also discussed.

Saliva analysis using metal-organic framework-coated miniaturized vials

BACKGROUND

In-vial microextraction is probably the simplest microextraction technique because it eliminates centrifugation and/or filtration steps while offering short extraction and desorption times. However, it has had limited applicability, mostly involving polydimethylsiloxane coatings and gas chromatography applications. Quite recently, one study introduced metal-organic framework (MOF)-coated glass vials for environmental analyses and liquid chromatography, thus combining the advantages of MOFs as adsorbents with the advantages of the in-vial approach, while not limiting the application to volatile analyses. Besides, a much higher exposure of the MOF to the sample due to the thin film coating available within the vial's inner walls is attained. Clearly, the applicability of this format for bioanalysis has not been evaluated, as there are not many stable and reusable sorbents useful for biological samples presenting high protein content. Besides, the in-vial technique must demonstrate to be valid for low-availability samples, such as saliva.

RESULTS

A vial with 2 mL-capacity and coated uniformly with a MOF has been developed to analyze saliva in a thin film solid-phase microextraction approach, while keeping an adequate analytical performance using only 50 μL of solvent for desorption. The procedure only requires 12.5 min of operation. Interestingly, the issues related to pore-blocking of the crystalline materials by proteins present in the saliva samples are solved with a simple cleaning protocol that also ensures a high reusability of the vials (more than 50 times). Seven bisphenols were determined in saliva with these devices, reaching limits of detection down to 0.10 μg L-1, and with inter-vial and inter-day precision values as RSD (in %) lower than 15% at a low concentration level (2.0 μg L-1).

SIGNIFICANCE

A device is presented to analyze complex saliva samples with a novel miniaturized MOF-coated vial ensuring proper reusability, while addressing the challenge of protein clogging and, at the same time, keeping adequate analytical performance with short analysis times. This approach represents significant progress in the bioanalytical sample preparation field, particularly when using sorbent porous materials integrated within miniaturized devices.

The Construction of Highly Conductive Framework in Mn3O4@C-MWCNTs Slurry for Aqueous Zinc-Based Semi-Solid Flow Batteries

Aqueous zinc-based semi-solid flow batteries (AZSSFBs) are promising large-scale energy storage devices due to their low cost and superior safety. The formation of a conductive network in the slurry plays an important role in the capacity of active materials and the stability of suspension. Meanwhile, the suspension stability of the slurry will determine the cycle life of AZSSFBs. Herein, metal-organic-framework-derived carbon-coated Mn3O4@C composites are fabricated and dispersed in the aqueous electrolyte to construct a stable 3D conductive carbon framework in slurry by combining multi-walled carbon nanotubes (MWCNTs). The 3D conductive carbon framework can not only facilitate rapid electron transportation, but also enhance the suspension stability of slurry, ensuring stable electron conduction for Mn3O4 in the fluidic semi-solid slurry. Based on Mn3O4@C-MWCNTs semi-solid slurry, AZSSFBs display enhanced electrochemical performance.

Solvent-Driven Synthesis of DNA-Based Liquid Crystalline Organogels with Extraordinary Stretchability, Self-Healing, and Higher-Order Structural Assembly

The fabrication of liquid crystalline (LC) organogel via supramolecular interactions between Deoxyribonucleic acid (DNA) and lyotropic cationic surfactant containing cyanobiphenyl moiety is reported. The fabricated organogel endows dominantly viscous behavior in dimethyl sulfoxide (DMSO) and elastic behavior in n-propanol (n-PrOH), respectively. By judiciously controlling the viscosity, DMSO organogels can be drawn to form a fiber with an elongation of up to 4.6 × 103%, emphasizing extraordinary stretchability. Higher-order structures, such as yarn and a co-alignment matrix for anisotropic particles, can be produced by assembling a single fiber. On the other hand, free-standing n-PrOH organogels demonstrate a remarkable storage modulus of 105 Pa and manifest self-healing properties. Finally, a sustainable method by transforming n-PrOH gel into an aerogel through critical point drying (CPD), enabling its use as an adsorbent while simultaneously enhancing its reusability is proposed. It is envisaged that these DNA-based organogels, through conceivable combinations between DNA as a building block and cationic surfactant with functionalities as a counterpart, will contribute to significant progress in DNA-based multi-functional organogels.

Precise C2H2 Adsorption Affinity Modulation by Nitrogen Functionalization in Isostructural Coordination Networks

Meticulous regulation of pore chemistry is essential for elucidating the intricate mechanism of the adsorption efficacy of porous materials. However, it is a great challenge to address the functionalization of pore chemistry while preserving pore size and geometry. In this study, the robust NPU-1 series network is selected as a platform to address this challenge. By regulating the nitrogen distribution in bilayer-pyridine ligands, a series of coordination networks (NPU-1-TPB/TPP/TPT) with the same pore size and geometry but different pore polarity is obtained, affording an increase in C2H2 enthalpies from -28.3 to -33.1 kJ mol-1. In situ, infrared spectroscopy uncovers the enhanced C2H2 interaction with the central phenyl ring of bilayer-pyridine ligands with the extent of nitrogen functionalization.

Instantaneous Hydrolysis of Methyl Paraoxon Nerve Agent Simulant Is Catalyzed by Nontoxic Aminoguanidine Imines

Exposure to organophosphate-based nerve agents and pesticides poses health and security threats to civilians, soldiers, and first responders. Thus, there is a need to develop effective decontamination agents that are nonhazardous to human health. To address this, we demonstrate that instantaneous hydrolysis of methyl paraoxon (Me-POX), a nerve agent simulant, can be achieved in the presence of aminoguanidine imines at pH 10: ● the pyridine-4-aldehyde aminoguanidine-imine (1) and ● the 2,3-butanedione aminoguanidine-imine (2). The hydrolysis of Me-POX under these conditions is substantially faster than that of the state-of-the-art decontaminating agent, Dekon-139 (2,3-butanedione oxime, potassium salt). Furthermore, Dekon-139 shows adverse effects when applied on skin surfaces, making it of great interest to develop safer but effective decontaminating agents for neutralizing nerve agents and pesticides exposed to skin-surface areas. Our pharmaceutically relevant aminoguanidine derivatives serve as rather nontoxic and safe decontaminating agents for organophosphate-based nerve agents and pesticides. The hydrolytic degradation products of Me-POX by our aminoguanidine-based imines and Dekon-139 are pH dependent. At pH > 10, Me-POX is hydrolyzed to give dimethyl phosphate as the exclusive product, whereas at pH < 9, the major product of hydrolysis is methyl 4-nitrophenyl phosphate (M4NP). We applied Quantum Mechanics calculations to investigate the mechanism of this dramatically accelerated decontamination process. We predict that in the rate-determining transition state, both 1 and 2 stabilize the reaction center through hydrogen bonding. Compared to Dekon-139, the rate constants of the rate-determine steps (RDS) are predicted to be over 9,000 times larger for 1 and over 600 times larger for 2, explaining the improvement. Quantum Mechanics calculations rationalize the pH-dependent hydrolysis products of the Me-POX in the gas phase, and gauge-including atomic orbital (GIAO)-31P NMR chemical shift calculations confirm the experimental values.

Decorating channel walls in ordered macroporous ZIF-8 with hydrophilic PEG to immobilize lipase for efficient chiral resolution

The development of efficient immobilization support for the enhancement of enzyme activity and recyclability is a highly desirable objective. Single-crystalline ordered macro-microporous ZIF-8 (SOM-ZIF-8), has emerged as a highly effective matrix for enzyme immobilization, however, the inherent hydrophobic nature limits its further advancement. Herein, we have customized the immobilization of the Pseudomonas cepacia lipase (LP) in the modification-channels of SOM-ZIF-8 by functionalizing the inner surface-properties with polyethylene glycol (PEG) (LP@SOM-ZIF-8-PEG), and significant enhancement of the activity and (thermal, solvent and cyclic) stability can be realized. The incorporation of PEG into SOM-ZIF-8 regulates its inner surface charge and hydrophobic properties, thereby enhancing enzyme loading, facilitating enzyme conformational adjustments, and achieving a uniform dispersion of LP in SOM-ZIF-8-PEG. LP@SOM-ZIF-8-PEG not only demonstrates a pronounced elevation in enzyme loading and activity over LP@SOM-ZIF-8 but also shows an enzyme activity that is impressively three times greater than LP@ZIF-8. It can completely resolve the 1-phenylethanol racemate in 60 min, with a conversion close to 50 % and an enantioselectivity of 99.8 %. After nine cycles of reuse, the LP@SOM-ZIF-8-PEG still holds onto 95 % of its initial activity. The excellent catalytic performance and stability of LP@SOM-ZIF-8-PEG, along with the universality of the PEG modification strategy for other enzymes, make this work promising in industrial applications.

Efficient Separation of Dibranched Hexane from its Linear and Monobranched Isomers via the Synergistic Molecular Sieving and Pore Shape-Matching Strategy

The efficient separation of dibranched hexane from its linear and monobranched isomers is crucial but challenging for the production of high-RON (Research Octane Number) gasoline. Here, a strategy is presented to realize the efficient separation of high-purity (99.8%) dibranched 2,2-dimethylbutane from a ternary mixture of n-hexane/3-methylpentane/2,2-dimethylbutane by combining the sieving aperture and shape-matching cavity within the ultramicroporous metal-organic framework, Zn4O(NTB)2 (H3NTB = 4,4',4″-Nitrilotrisbenzoic acid). The static adsorption isotherms exhibit both high capacity for linear n-hexane (2.72 mmol g-1) and monobranched 3-methylpentane (2.59 mmol g-1). Dynamic breakthrough experiment shows that Zn4O(NTB)2 is capable of completely separating high-RON dibranched 2,2-dimethylbutane with a record-high productivity (0.98 mmol g-1), which is ≈1.6 times that of the previous benchmark material. Single-crystal X-ray diffraction of guest-loaded Zn4O(NTB)2 reveals that there exist high-density elongated cavities that match well with the shape of both n-hexane and 3-methylpentane, which can account for the high adsorption capacity for both of them. This work demonstrates the effectiveness of the synergistic effect of molecular sieving and shape matching in the efficient production of dibranched hexane from complex mixture.

Enhancing strategies of MOFs-derived materials for microwave absorption: review and perspective

Microwave absorption materials (MAMs) gradually exhibit crucial applications in reducing electromagnetic wave (EMW) pollution, avoiding EMW information leakage, and solving radar stealth. Metal-organic frameworks (MOFs)-derived materials are flourishing in the domain of EMW absorption attributed to their especial structures, heteroatom doping and controllable components. Herein, various strategies to enhance the EMW absorption ability of MOFs-derived materials are outlined, covering structural design and compositional regulation. Additionally, the applications of MOFs-derived composites in EMW absorption domains are introduced in detail, with emphasis on recent progress in MOFs-derived composites materials like foams, films and aerogels. Finally, existent opportunities, challenges and future orientations of MOFs-derived MAMs are proposed.

Retrieving the Stability and Practical Performance of Activation-Unstable Mesoporous Zr(IV)-MOF for Highly Efficient Self-Calibrating Acidity Sensing

The practical applications of activation-unstable mesoporous metal-organic frameworks (MOFs) are often constrained by their structural instability. However, enhancing their stability could unlock valuable functionalities. Herein, we stabilized the otherwise unstable, post-activated structure of a novel mesoporous Zr(IV)-MOF, NKM-809, which constructed from a pyridine-containing amphiprotic linker (PPTB). We applied two strategies: mixed-linker synthesis and linker installation. In the mixed-linker approach, we incorporated an auxiliary linker, TPTB, which resembles PPTB, during synthesis to improve the framework's stability. In the linker installation approach, we introduced a ditopic carboxylate linker (BPDC) into the coordination-unsaturated sites of NKM-809. These strategies produced stabilized derivatives, named NKM-808.X (X=χPPTB) and NKM-809-BPDC, which exhibit pH-responsive dual-wavelength fluorescence at distinct emission wavelengths. Remarkably, these emissions shift oppositely upon protonation and dissociation, distinguishing them as highly sensitive, self-calibrating acidity sensors. In NKM-809-BPDC, an additional quenching of the linker-emission (419 nm) minimizes inherent interference, enabling integrated quality and lifespan self-monitoring. Theoretical calculations identified transitions between (n, π*) and (π, π*) emission states during the sensing process and highlighted the role of a stable mesoporous network in achieving stronger protonation response. These findings showcase the potential of stabilized mesoporous MOFs for practical applications, alongside valuable insights into strategies for optimizing such materials.

Free Volume Space of Polymers as a New Functional Nanospace: Synthesis of Guest Polymers

Nanospace has been used as a specific field for syntheses and assemblies of molecules, polymers, and materials. Free volume space among polymer chains is related to their properties, such as permeation of gas and small molecules. However, the void has not been used as a functional nanospace in previous works. The present work shows synthesis of guest conductive polymers in free volume space of conventional synthetic resins and rubbers as a new nanospace. Vapor of heteroaromatic monomer and oxidative agent is diffused into the soft dynamic nanospace among the polymer chains under ambient pressure at low temperature. The oxidative polymerization provides the conductive polymers, such as polypyrrole (PPy), in the free volume space of poly(methyl methacrylate) (PMMA), polypropylene (PP), silicone rubber (SR), and polyurethane rubber (PU). The ratio of the free volume decreases with the infiltration of the conductive polymers. The composites exhibit the improved mechanical and gas barrier properties. The rubbers containing PPy are used as mechanical-stress sensors with both the conductivity and flexibility. The free volume space of resins and rubbers can be used as a new dynamic nanospace for synthesis of functional polymer composites.

Thermostability of tetanus toxoid vaccine encapsulated in metal-organic frameworks

Most vaccines require refrigerated transport and storage, which is costly, challenging in low-resource settings, and results in the loss of up to 50% of vaccines globally due to "cold-chain" failures. Here, tetanus toxoid vaccine (TT) was thermostabilized by encapsulation within a metal-organic framework (MOF), zeolitic imidazolate framework-8 (TT@ZIF-8). Its physicochemical properties were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and confocal microscopy. Unencapsulated TT fell below the 80% activity threshold within 4 days at 40˚C and 60˚C according to immunoassay analysis. Aqueous suspensions of TT@ZIF-8 also declined below 80% activity within a week at both temperatures, likely due to MOF degradation in water. Dried TT@ZIF-8 performed better, retaining 80% stability for 33 days at 40˚C and 22 days at 60˚C. When TT@ZIF-8 was suspended in a non-aqueous mixture of propylene glycol and ethanol, it remained 80% stable for approximately 4 months at 40˚C and 2.5 months at 60˚C. Arrhenius modeling predicted this formulation may qualify for "controlled temperature chain" designation, allowing partial vaccine removal from the cold chain. These studies suggest that MOF encapsulation of vaccines like TT can enable dramatic improvements in vaccine stability during storage without refrigeration.

Effect of Functional Group-Modified UiO-66 on the Dehydrogenation of Ammonia Borane

Ammonia borane (AB) has attracted much attention in the field of solid-state hydrogen storage due to its high hydrogen storage capacity. Nanoconfinement in UiO-66 can reduce the hydrogen release temperature. In particular, terephthalic acid was used as a linker to further improve the dehydrogenation properties through the modification of -NH2, -OH, -NO2, -Br, and -F groups. The hydrogen release content of 0.5AB/UiO-66 was 1.98 wt.%, whereas the hydrogen release content of UiO-66-2OH modified by -OH groups increased to 3.85 wt.%. The non-covalent interaction results show that -NH2 and -OH preferred adsorption with -BH3, and the H in -NH2 and -OH were able to interact directly with the H in AB to modify the dehydrogenation process of AB, whereas -NO2, -Br, and -F indirectly affected the charge density of hydrogen atoms in AB to alter the dehydrogenation property of AB. The modification of functional groups provides a theoretical basis for the design of high-performance MOF nanoconfinement AB composite hydrogen storage materials.

Calcium l-Malate and d-Tartarate Frameworks as Adjuvants for the Sustainable Delivery of a Fungicide

Agrichemical adjuvants that combine a highly selective, efficient, and active mode of operation are critically needed to realize a more sustainable approach to their usage. Herein, we report the synthesis and full characterization of two new metal-organic frameworks (MOFs), termed UPMOF-1 and UPMOF-2, that were constructed from eco-friendly Ca2+ ions and naturally occurring, low-molecular weight plant acids, l-malic and d-tartaric acid, respectively. Upon structural elucidation of both MOFs, a widely used fungicide, hexaconazole (Hex), was loaded on the structures, reaching binding affinities of -5.0 and -3.5 kcal mol-1 and loading capacities of 63% and 62% for Hex@UPMOF-1 and Hex@UPMOF-2, respectively, as a result of the formation of stable host-guest interactions. Given the framework chemistry of the MOFs and their predisposition to disassembly under relevant agricultural conditions, the sustained release kinetics were determined to show nearly quantitative release (98% and 95% for Hex@UPMOF-1 and Hex@UPMOF-2, respectively) after >500 h, a release profile drastically different than the control (>80% release in 24 h), from which the high efficiency of these new systems was established. To confirm their high selectivity and activity, in vitro and in vivo studies were performed to illustrate the abilities of Hex@UPMOF-1 and Hex@UPMOF-2 to combat the known aggressive pathogen Ganoderma boninense that causes basal stem rot disease in oil palm. Accordingly, at an extremely low concentration of 0.05 μg mL-1, both Hex@UPMOF-1 and Hex@UPMOF-2 were demonstrated to completely inhibit (100%) G. boninense growth, and during a 26 week in vivo nursery trial, the progression of basal stem rot infection was completely halted upon treatment with Hex@UPMOF-1 and Hex@UPMOF-2 and seedling growth was accelerated given the additional nutrients supplied via the disassembly of the MOFs. This study represents a significant step forward in the design of adjuvants to support the environmentally responsible use of agrichemical crop protection.

Tunable Platform Capacity of Metal-Organic Frameworks via High-Entropy Strategy for Ultra-Fast Sodium Storage

Precise regulation of the platform capacity/voltage of electrode materials contributes to the efficient operation of sodium-ion fast-charging devices. However, the design of such electrode materials is still in a blank stage. Herein, based on tunable metal-organic frameworks, we have designed a novel material system-two-dimensional high-entropy metal-organic frameworks (HE-MOFs), which exhibits unique properties in sodium storage and is of vital importance for realizing fast-charging batteries. Furthermore, we have found that the high-entropy effect can regulate the electronic structure, the sodium-ion migration environment, and the sodium-ion storage active sites, thereby meeting the requirements of electrode materials for sodium-ion fast-charging devices. Impressively, the HE-MOFs material still maintains a reversible specific capacity of 89 mAh g-1 at a current density of 20 A g-1. It presents an ideal sodium storage voltage plateau of approximately 0.5 V, and its platform capacity is increased to 122.7 mAh g-1, far superior to that of Mn-MOFs (with no platform capacity). This helps to reduce safety hazards during the fast-charging process and demonstrates its great application value in the fields of fast-charging sodium-ion batteries and capacitors. Our research findings have broken the barriers to the application of non-conductive MOFs as energy storage materials, enhanced the understanding of the regulation of platform capacity and voltage, and paved the way for the realization of high-security sodium-ion fast-charging devices.

Adaptive representation of molecules and materials in Bayesian optimization

Bayesian optimization (BO) is increasingly used in molecular optimization and in guiding self-driving laboratories for automated materials discovery. A crucial aspect of BO is how molecules and materials are represented as feature vectors, where both the completeness and compactness of these representations can influence the efficiency of the optimization process. Traditionally, a fixed representation is chosen by expert chemists or applying data-driven feature selection methods on available labeled datasets. However, when dealing with novel optimization tasks, prior knowledge or large datasets are often unavailable, and relying on these even can introduce bias into the search process. In this work, we demonstrate a Feature Adaptive Bayesian Optimization (FABO) framework, which integrates feature selection in the Bayesian optimization process with Gaussian processes to dynamically adapt material representations throughout the optimization cycles. We demonstrate the effectiveness of this adaptive approach across several molecular optimization tasks, including the discovery of high-performing metal-organic frameworks (MOFs) in three distinct tasks, each involving unique property distributions and requiring a distinct representation. Our results show that the adaptive nature of the representation leads to outperforming random search baseline and scenarios where prior knowledge of the feature space is available. Notably, for known optimization tasks, FABO automatically identifies representations that are aligned with human chemical intuition, validating its utility for optimization tasks where such insights are not available in advance. Lastly, we show how a suboptimal representation, e.g., when missing key features, can adversely impact BO performance, highlighting the importance of starting from a full feature set and adapt it to different tasks. Our findings highlight FABO as a robust approach for navigating large, complex materials search spaces in automated discovery campaigns.

Two-dimensional conjugated metal-organic frameworks for electrochemical energy conversion and storage

Effective electrocatalysts and electrodes are the core components of energy conversion and storage systems for sustainable carbon and nitrogen cycles to achieve a carbon-neutral economy. Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) have emerged as multifunctional materials for electrochemical applications benefiting from their similarity to graphene with remarkable conductivity, abundant active sites, devisable components, and well-defined crystalline structures. In this review, the structural design strategies to establish active components with a maximum degree through redox-active ligand assembly in 2D c-MOFs are briefly summarized. Next, recent representative examples of 2D c-MOFs applied in electrocatalysis (hydrogen/oxygen evolution and oxygen/carbon dioxide/nitrogen reduction) and energy storage systems (supercapacitors and batteries) are introduced. The synergistic effect of multiple components in 2D c-MOFs is particularly emphasized for enhanced performance in electrochemical energy conversion and storage systems. Finally, an outlook and challenges are proposed for realizing more active components, elucidating the reaction mechanism involving the derived structures, and achieving low-cost economy in practical applications.

Controlled Growth of Highly Defected Zirconium-Metal-Organic Frameworks via a Reaction-Diffusion System for Water Remediation

The relentless growth of metal-organic framework (MOF) chemistry is paralleled by the persistent urge to control the MOFs physical and chemical properties. While this control is mostly achieved by solvothermal syntheses, room temperature procedures stand out as more convenient and sustainable pathways for the production of MOF materials. Herein, a novel approach to control the crystal size and defect numbers of a dihydroxy-functionalized zirconium-based metal-organic framework (UiO-66(OH)2) at room temperature is reported. Through a reaction-diffusion method in a 1D system, zirconium salt was diffused into an agar gel matrix containing the organic linker to form nanocrystals of UiO-66(OH)2 with tailored structural features that include crystal size distribution, surface area, and defect number. By variation of the synthesis parameters of the system, hierarchical MOF nanocrystals with an average size ranging from 30 nm up to 270 nm and surface areas between 201 and 500 m2 g-1 were obtained in a one-pot synthetic route. To stress the importance of crystal size, morphology, and structural defects on the adsorption properties of UiO-66(OH)2, the adsorption capacity of the MOF toward methylene blue dye was tested with the largest and most defected crystals achieving the best performance of 202 mg/g. The distinctive structural characteristics including the hierarchical micromesoporous frameworks, the nanosized particles, and the highly defective crystals obtained by our synthesis procedure are deemed challenging through the conventional synthesis methods. This work paves the way for engineering MOF crystals with tunable physical and chemical properties, using a green synthesis procedure, for their advantageous use in many desirable applications.

High performance supercapacitors driven by the synergy of a redox-active electrolyte and core-nanoshell zeolitic imidazolate frameworks

The selection of appropriate electrolytes plays a crucial role in improving the electrochemical performance of the supercapacitor electrode. The electrolyte helps to select an appropriate potential window of the device, which is directly related to its energy density. Also, the selection of an appropriate electrode material targets the specific capacitance. Therefore, in this work, we targeted an electrode material based on a ZIF-8@ZIF-67 (Z867) core-nanoshell structure and tested its performance in redox active electrolyte (RAE), i.e., 0.2 M K3[Fe(CN)6] in 1 M Na2SO4. The synergy between the core-nanoshell electrode having ZIF-8 as a core and ZIF-67 as a nanoshell along with RAE further complements the redox active sites, resulting in the improved charge transport. Therefore, when the Z867 core-nanoshell electrode is tested in a three-electrode system, it outperforms pristine ZIF-8 and ZIF-67 electrode materials. The working electrode modified with the Z867 core-nanoshell showed a maximum specific capacitance of 496.4 F g-1 at 4.5 A g-1 current density with the RAE, which is much higher than that of the aqueous electrolyte. A Z867-modified working electrode was assembled as the positive and negative electrode in a symmetrical cell configuration to create a redox supercapacitor device for practical application. The constructed device displayed maximal energy and power densities of 49.6 W h kg-1 and 3.2 kW kg-1 respectively, along with a capacitance retention of 92% after 10 000 charge-discharge cycles. Hence, these studies confirm that using RAE can improve the electrochemical performance of electrodes to a greater extent than that of aqueous electrolyte-based supercapacitors.