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.

Recent Advances in Superspreading-Based Confined Synthesis and Assembly of Functional Nanomaterials

The rapid and complete spreading of liquids on surfaces, which is defined as superspreading, is of great importance in academic research and practical applications. The strong shear flow force during the superspreading process and the obtained confined stable and homogeneous thin liquid layers have great potential in the assembly of functional nanomaterials and confined synthesis. This review aims to summarize the fundamental understanding and emerging applications of superspreading-based confined synthesis and assembly of functional nanomaterials. First, several typical superspreading processes are briefly introduced, followed by highlighting the unique properties and design principles. Then, details about the confined superspreading liquid layers for highly efficient synthesis of functional thin films and the superspreading-induced shear flow to assembly nanomaterials into high-quality nanocomposite materials are presented. The following section then describes the emerging applications of the fabricated functional thin films and nanocomposites. Finally, an outlook for future development is also proposed.

Tailoring Catalysts for CO2 Hydrogenation: Synthesis and Characterization of NH2-MIL-125 Frameworks

Copper nanoparticles have been integrated onto the framework of modified NH2-MIL-125(Ti), a metal-organic framework (MOF), and evaluated as catalysts for converting CO2 into valuable products. The modified MOF was achieved through a post-synthetic modification process involving the partial replacement of titanium with zirconium or cerium within the MOF's structure. The objective behind this alteration is to create a synergistic effect between the MOF, serving as a support matrix, and the embedded copper nanoparticles, thereby enhancing the performance of the catalyst. The obtained catalysts were characterized and evaluated in the hydrogenation of CO2 to methanol under different experimental conditions, reaching CO2 conversions of up to 5%, with a selectivity towards methanol that reached values of up to 60%. According to the obtained results, the catalyst composed of Ti, Zr and Cu stood out for having the highest CO2 conversion and selectivity towards methanol, in addition to practically inhibiting the production of methane. These results demonstrate that the interaction of the framework with the Cu nanoparticles, and thus its catalytic properties, can be changed by modifying the properties of the MOF.

Photocatalytic Dehalogenation of Aryl Halides Mediated by the Flexible Metal-Organic Framework MIL-53(Cr)

The catalytic potential of flexible metal-organic frameworks (MOFs) remains underexplored, particularly in liquid-phase reactions. This study employs MIL-53(Cr), a prototypical "breathing" MOF capable of structural adaptation via pore size modulation, as a photocatalyst for the dehalogenation of aryl halides. Powder X-ray diffraction and Pair Distribution Function analyses reveal that organic solvents influence pore opening, while substrates and products dynamically adjust the framework configuration during catalysis. This structural flexibility enables precise tuning of photocatalytic efficiency via solvent-mediated control of the pore aperture. The results demonstrate that the dynamic behavior of MIL-53(Cr) facilitates enhanced catalytic activity and selectivity, advancing the application of flexible MOFs as tunable, enzyme-mimicking catalysts. These findings pave the way for the rational design of next-generation flexible photocatalysts.

Continuous and Large-Scale Preparation of Hierarchical Porous HKUST-1 via the "Nanofusion" Mechanism Using Liquid-Assisted Mechanosynthesis

Hierarchical porous metal-organic frameworks (HP-MOFs) have attracted considerable attention because of their hierarchical pores, which can address the slow mass transfer and less exposure of active sites in pristine microporous MOFs. Although several preparation methods have been developed to date, a large-scale technique for the synthesis of HP-MOFs is still lacking. In this study, we report a novel method for the large-scale synthesis of HP-HKUST-1 based on liquid-assisted spiral gas-solid two-phase flow (LA-S-GSF). This method ingeniously uses a nebulizer to promote the rapid synthesis of nano-HKUST-1 by introducing trace amounts of water during the S-GSF reaction. During the washing and drying process, these nanoparticles were fully fused to form nanocrystalline aggregates, resulting in a hierarchical porous structure with a large number of micropores, mesopores, and macropores. The pore size distribution can be regulated by changing the drying temperature to obtain HP products with combinations of micropores and mesopores, micropores and macropores, and the formation mechanism of the HP structure was also explored. This method required only 11 min of reaction time to obtain 25.2 g of HP-HKUST-1 in 96% yield, with a corresponding space-time yield (STY) of 6.9 × 104 kg m-3 day-1.

Scalable and Low-Energy Synthesis of Metal-Organic Frameworks by a Seed-Mediated Approach

The synthesis of metal-organic frameworks (MOFs) by low energy input has been a long-term target for practical applications yet remains a great challenge. Herein, we developed a low-energy MOF growth strategy at a temperature down to 50 °C by simply introducing seeds into the reaction system. The MOFs are continuously grown on the surface of the seeds at a growth rate dozens of times higher than that of conventional solvothermal synthesis at low temperature, while the resulting MOFs possess high crystallinity, porosity, and stability similar to solvothermal seeds. Remarkably, the obtained MOFs feature high-density structural defects with Lewis acidity, thereby displaying more than one order of magnitude higher activity than the MOFs obtained by the conventional solvothermal method in the iodination reaction of substituted arenes. This low-energy synthetic approach is readily scaled up, which would be a significant step forward in the dream of the MOF industry.

Thermal Chemisorption and Reduction of Carbon Dioxide on UiO-66(Zr) and MIL-100(Fe)

The continuous increase in global energy consumption has caused a considerable increase in CO2 emissions and environmental problems. To address these challenges, adsorbents and catalytic materials that can effectively reduce the CO2 levels in the atmosphere should be developed. Metal-organic frameworks (MOFs) have emerged as promising materials for CO2 capture owing to their high surface areas and tunable structures. Herein, the CO2 adsorption properties of MIL-100(Fe) and UiO-66(Zr) were investigated. Both MOFs exhibited excellent thermal stability and high CO2 adsorption capacities at 300 K, and they maintained good adsorption properties at 500 K compared to those of activated carbon fiber owing to their high adsorption potentials. A slight change in the UiO-66(Zr) structure and no change in the MIL-100(Fe) structure were observed under the CO2 atmosphere at 500 K. At that time, CO emissions and changes in the carboxyl and OCO functional groups were observed on MIL-100(Fe), suggesting a mechanism of CO2 reduction to CO on the bare Fe(II) sites. These findings confirm the potential of MOFs for the thermo-catalytic reduction of CO2 to achieve effective CO2 capture and conversion.

Efficient uremic toxins adsorption from simulated blood by immobilization of metal organic frameworks anchored Sephadex beads

The current study outlines the removal of Creatinine, p-Cresol sulfate, and Hippuric acid from simulated blood using three new granules: Fe-BTC@Sephadex, Cu-BTC@Sephadex, and Co-BTC@Sephadex. Beads were used to adsorbed toxic chemicals, and the effects of various experimental parameters were examined in the adsorption optimization process. The framework's adsorption isotherms were explained by the application of the Freundlich and Langmuir models. The kinetics of adsorption is represented by a pseudo-first and second-order equation. The morphology and structure of the Fe-BTC@ Sephadex, Co-BTC@ Sephadex, and Cu-BTC@Sephadex beads were investigated using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The adsorption capacities for creatinine were 545.69, 339.76, and 189.88 mg/g for Fe-BTC@ Sephadex, Cu-BTC@ Sephadex, and Co-BTC@ Sephadex, respectively, according to the results; the corresponding adsorption capacities for hippuric acid were 323.78, 206.79, and 68.059 mg/g, and the maximum adsorption capacities for p-Cresol sulfate were 122.65, 71.268, and 40.347 mg/g, respectively. These were, in fact, promising findings that have implications for an industrial-scale transportable artificial kidney.

Enzyme-Photocoupled Catalytic Systems Based on Zirconium-Metal-Organic Frameworks

Green, low-carbon, and efficient chemical conversions are crucial for the sustainable development of modern society. Enzyme-photocoupled catalytic systems (EPCS), which mimic natural photosynthesis, utilize solar energy to drive biochemical reactions, providing emergent opportunities to address the limitations of traditional photocatalytic systems. However, the integration and compatibility of photocatalysis and biocatalysis present challenges in designing highly efficient and stable EPCS. Zirconium-based metal-organic frameworks (Zr-MOFs) with outstanding chemical and thermal stability, large surface area, and tunable pore size are ideal candidates for supporting enzymes and enhancing photocatalytic processes. This review aims to integrate Zr-MOFs with EPCS to further promote the development of EPCS. First, an overview of the basic components and design principles of EPCS is provided, highlighting the importance of the unique properties of Zr-MOFs. After that, three different strategies for combining enzymes with Zr-MOFs are summarized and their respective advantages are evaluated. Finally, the development opportunities and some problems to be solved in this field are proposed.

Nanoscale Rhodium(I) Based Metal-Organic Framework Demonstrating Intense NIR-II Luminescence for Bioimaging

Although luminescent metal-organic frameworks (MOFs) have been widely reported, rare examples were found to emit in the second near-infrared (NIR-II, 1000-1700 nm) window. In this work, two nanoscale rhodium(I)-based MOFs (Rh-1@SDS and Rh-1@DSPE-PEG) have been controllably constructed in the aqueous dispersions of sodium dodecyl sulfate (SDS) and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy-poly(ethylene glycol) (DSPE-PEG), wherein micelle- and vesicle-like aggregates form, respectively, with high colloidal stability. The vesicular dispersion of Rh-1@DSPE-PEG exhibits intense NIR-II luminescence at 1125 (1245, shoulder) nm. Consequently, this nanoMOF was used as an NIR-II luminescence probe, indicative of high-resolution systemic and local vascular imaging, where the postoperative recovery process of flap transplantation was clearly visualized. Meanwhile, it also demonstrates superior tumor targeting in the NIR-II window. To the best of our knowledge, this research represents the first example of nanoMOFs having intense NIR-II luminescence and excellent imaging capabilities.

Next-Generation Metal-Organic Frameworks: Shaping the Future of Steroid Compound Management

Metal-Organic Frameworks (MOFs), as a new type of porous material, have attracted widespread attention in the fields of chemistry, materials science, and biomedicine owing to their unique structural characteristics and potential for functionalization. This review summarizes the latest research progress of MOFs in the field of steroid compounds, including the latest research progress of MOFs in the purification and separation of steroids, sensing and detection, catalytic transformation, and drug delivery. First, we explore how the porous structure and chemical functionalization of MOFs achieve efficient separation and purification of steroid compounds. Second, the high sensitivity and selectivity of MOFs as sensing materials in steroid detection, as well as their application potential in actual sample analysis, are analyzed. Furthermore, the role of MOFs in steroid catalytic transformation reactions is discussed, including their performance as catalysts or catalyst carriers. Finally, we focus on the innovative applications of MOFs in drug delivery systems, especially their advantages in controlled release and targeted drug delivery. This article also explores the future development trends and application prospects of MOFs in the field of steroids, highlighting the challenges and opportunities in material design, functionalization strategies, and practical implementations. Through this review, we aim to provide a comprehensive theoretical basis and practical guidance for further research and application of MOFs in the field of steroids.

Conductive Metal-Organic Frameworks and Their Electrocatalysis Applications

Recently, electrically conductive metal-organic frameworks (EC-MOFs) have emerged as a wealthy library of porous frameworks with unique properties, allowing their use in diverse applications of energy conversion, including electrocatalysis. In this review, the electron conduction mechanisms in EC-MOFs are examined, while their electrical conductivities are considered. There have been various strategies to enhance the conductivities of MOFs including ligand modification, the incorporation of conducting materials, and the construction of multidimensional architectures. With sufficient conductivities being established for EC-MOFs, there have been extensive pursuits in their electrocatalysis applications, such as in the hydrogen evolution reaction, oxygen reduction reaction, oxygen evolution reaction, N2 reduction reaction, and CO2 reduction reaction. In addition, computational modeling of EC-MOFs also exerts an important impact on revealing the synthesis-structure-performance relationships. Finally, the prospects and current challenges are discussed to provide guidelines for designing promising framework materials.

Construction of CeCu x -BTC/CN S-type heterojunctions and photocatalytic CO2 reduction to CO and CH4

S-type heterojunction photocatalysts (CeCu x -BTC/CN) of cerium-copper bimetallic organic framework (CeCu x -BTC) and graphitic carbon nitride (g-C3N4) were constructed by a simple solvothermal method using cerium nitrate, copper nitrate, and urea as the raw materials, and 1,3,5-benzene-tricarboxylic acid as the ligand for the photocatalytic CO2 reduction to CO and CH4. The results show that the built-in electric field constructed by Fermi energy level flattening transfers the electrons in an S-type manner, which not only preserves the strong reducing properties of the electrons in the material but also provides the maximum redox capacity and enables the composite samples to obtain higher visible-light trapping capacity and improve the separation efficiency of the carriers while refining the crystal particles. With the addition of only 1 mL of H2O as the proton supply source, CeCu0.05-BTC/CN exhibits the optimal photocatalytic performance. The CO and CH4 yields were 64.44 and 0.5575 μmol g-1, which were 7.56 and 2.42 times higher than those of g-C3N4, respectively, and the catalytic performances were basically stable after cycling tests.

Facile synthesis of ZIF-8@GO composites for enhanced adsorption of cationic and anionic dyes from their aqueous solutions

In this study, zeolitic imidazolate frameworks (ZIFs) and ZIF-8-graphene oxide (ZIF-8@xGO) composites were prepared at room temperature to be used as adsorbents for cationic (methylene blue (MB)) and anionic dyes (methyl orange (MO)) from their aqueous solutions. The structural characteristics confirmed the successful preparation of amorphous ZIF-8 and its ZIF-8@GO composites at room temperature. The BET surface area of the ZIF-8@0.5GO composite was estimated to be 286.22 m2 g-1, with a mean pore diameter of 3.34 nm. The adsorption study confirmed that dye removal efficiency of ZIF-8 was significantly enhanced when blended with GO. The maximum removal efficiency of the ZIF-8@0.5GO composite was achieved within 60 min, and the removal percentages of MB and MO dyes were 95.2% and 94.6%, respectively. These values were close to those achieved by GO at 60 min (96.2% for MB and 96.3% for MO). The kinetic study confirmed that the adsorption data of MB onto GO, ZIF-8, and the ZIF-8@xGO composites fitted the non-linear pseudo-first-order kinetic model, while the adsorption of MO dye obeyed the non-linear pseudo-second-order kinetic model. Moreover, the adsorption isotherm study confirmed that the adsorption of both MB and MO dyes onto the ZIF-8 and its ZIF-8@xGO composites were fitted to the Langmuir model, which indicates a chemical adsorption process. The estimated maximum adsorption capacity of the ZIF-8@0.5GO composite towards MB and MO were 87.39 and 82.78 mg g-1, which are much higher than that achieved by pure ZIF-8 and very close to that obtained by pure GO. This indicates that our prepared ZIF-8@GO composites are comparable to pure GO. The thermodynamic study confirmed that adsorption of both the dyes onto the prepared materials is endothermic, spontaneous, and thermodynamically favorable.

Functional crystalline porous framework materials based on supramolecular macrocycles

Crystalline porous framework materials like metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) possess periodic extended structures, high porosity, tunability and designability, making them good candidates for sensing, catalysis, gas adsorption, separation, etc. Despite their many advantages, there are still problems affecting their applicability. For example, most of them lack specific recognition sites for guest uptake. Supramolecular macrocycles are typical hosts for guest uptake in solution. Macrocycle-based crystalline porous framework materials, in which macrocycles are incorporated into framework materials, are growing into an emerging area as they combine reticular chemistry and supramolecular chemistry. Organic building blocks which incorporate macrocycles endow the framework materials with guest recognition sites in the solid state through supramolecular interactions. Distinct from solution-state molecular recognition, the complexation in the solid state is ordered and structurally achievable. This allows for determination of the mechanism of molecular recognition through noncovalent interactions while that of the traditional recognition in solution is ambiguous. Furthermore, crystalline porous framework materials in the solid state are well-defined and recyclable, and can realize what is impossible in solution. In this review, we summarize the progress of the incorporation of macrocycles into functional crystalline porous frameworks (i.e., MOFs and COFs) for their solid state applications such as molecular recognition, chiral separation and catalysis. We focus on the design and synthesis of organic building blocks with macrocycles, and then illustrate the applications of framework materials with macrocycles. Finally, we propose the future directions of macrocycle-based framework materials as reliable carriers for specific molecular recognition, as well as guiding the crystalline porous frameworks with their chemistry, applications and commercialization.

A Fluorinated Zinc-based Metal-Organic Framework for Efficient Separation of Butane Isomers via Pore Engineering

Separating n-butane/iso-butane is a challenging and energy-intensive task in the petrochemical industry. There have been only several adsorbents reported for C4 paraffins separation while they are confronted in real-world applications with either poor selectivity or low n-butane uptake capacity. In this study, a fluorinated zinc-based metal-organic framework (MOF), Znpyc-CF3, derived from Znpyc-CH3 is developed, which has fluorine-containing functional groups on the pore surface that can enhance the interaction with the linear n-butane. Remarkably, this fluorinated porous material demonstrates both high n-butane uptake (55.5 cm3 g⁻¹) and excellent selectivity (IAST selectivity = 187) at ambient temperature. Multicycle breakthrough experiments confirmed its practical performance for real gas mixtures. Znpyc-CF3 exhibits outstanding stability, maintaining its structural integrity after repeated sorption cycles and dynamic breakthrough tests under both dry and highly humid conditions. The preferential adsorption mechanism of n-butane is further elucidated through Grand Canonical Monte Carlo (GCMC) simulations and Density Functional Theory (DFT) calculations. Overall, this research presents an efficient and stable adsorbent for the separation of butane isomers.

Supercritical Ethane Processing of ZIF-8 Membranes towards Pressure-Resistant C3H6/C3H8 Separation

ZIF-8 membranes have shown great promise in industrial-scale C3H6/C3H8 separation. Nonetheless, sustainable preparation of pressure-resistant ZIF-8 membranes remains a grand challenge. In this study, we pioneered the use of supercritical ethane (scC2H6) as reaction medium for preparing pressure-resistant ZIF-8 membranes. Membrane growth in neutral organic environment was proven to have less disturbance to structure integrity compared with supercritical CO2 (scCO2). Gas permeation results indicated that obtained ZIF-8 membrane exhibited an ideal C3H6/C3H8 selectivity of 172.1 with C3H6 permeance of 5.9×10-9 mol ⋅ m-2 ⋅ s-1 ⋅ Pa-1. Of particular note, the membrane maintained stable C3H6/C3H8 selectivity of ~150 with C3H6 flux of ~1.6×10-3 mol ⋅ m-2 ⋅ s-1 at operation pressure of 6 bar, which was significantly different from ZIF-8 membranes obtained from scCO2 reaction medium. Through combining with advantages of zero pollutant discharge and full ligand recovery, our protocol holds great promise in sustainable preparation of pressure-resistant ZIF-8 membranes towards practical application in high-purity C3H6 production.

Metal-Organic Framework with Constrained Flexibility for Benchmark Separation of Hexane Isomers

Flexible metal-organic frameworks (MOFs) are promising candidates for adsorptive separations, but achieving a balance among flexibility, adsorption capacity, and selectivity remains challenging. Herein, we report a novel flexible MOF, Ni(bhdc)(ted)0.5 (ZUL-C6), incorporating hybrid three-dimensional alkane-bridged ligands, which realizes high-capacity molecular sieving for hexane isomer separation - a critical process in the petroleum industry. The alkyl-rich, confined pore system within the ZUL-C6 framework facilitated a strong affinity for n-hexane and 3-methylpentane. However, the narrow pore size and the constrained flexibility limited the uptake of 2,2-dimethylbutane (<4.0 mg/g), accompanied by a high gate-opening pressure. The gating behavior was elucidated by guest-loaded single-crystal (SC) X-ray diffraction and density functional theory (DFT) simulations, which revealed a unique SC to SC transformation driven by the non-centrosymmetric rotation of the 3D bhdc linker and distortion of the metal cluster and pillar units, along with a high deformation energy barrier. As a result, ZUL-C6 exhibited not only significantly higher uptake and selectivity than the industrially used 5 A molecular sieve, but also the record-high nHEX/3MP breakthrough uptake (92.8/73.9 mg/g) and unprecedented 22DMB producing time (309.2 min/g, corresponding to the productivity of 770 mmol/kg and yield of 92.8 %) among reported MOFs.

Dose-responsive phytotoxicity and oxidative stress induced by metal-organic framework PCN-224 in Arabidopsis thaliana seedlings

Metal-organic frameworks (MOFs) are advanced porous materials composed of metal ions and organic ligands, known for their unique structures and fascinating physio-chemical properties. To ensure their safe production and applications, it is crucial to thoroughly investigate their toxicity and environmental hazards. However, the potential risks of MOFs, particularly their impact on plants remained underexplored. Herein, we systematically assessed the phytotoxicity of PCN-224 on Arabidopsis thaliana (A. thaliana) due to its commercial availability and widespread use. To achieve this goal, A. thaliana seedlings were subjected to PCN-224 concentrations (10-300 µg/mL) and durations (1-12 days) in agar media, with a control group. PCN-224 slightly accelerated seed germination across all concentrations without altering the total germination rate. Exposure to a higher concentration of PCN-224 (300 µg/mL) significantly impaired A. thaliana development, reducing fresh weight (54.0 %) and root length (82.3 %) compared with control; however, lower exposure (10 µg/mL) showed minimal growth inhibition. Fluorescence microscopy showed that PI-labeled PCN-224 particles adhered to root surfaces and internalized in a concentration- and time-dependent manner, with notable xylem accumulation after 2 h. The net photosynthetic rate, transpiration rate, and stomatal conductance decreased by 54.25 %, 62.37 % and 38.53 %, respectively, compared with control, when the material concentration exceeded 100 µg/mL. Regarding the oxidative damage, higher PCN-224 exposure reduced antioxidant levels and downregulation of antioxidant-related genes resulted in a diminished oxidative stress response. Overall, our study highlights the potential risk of MOFs for plant growth and emphasizes the need to assess their environmental impact for sustainable agricultural practices.

Current landscape of metal-organic framework-mediated nucleic acid delivery and therapeutics

Nucleic acid drugs utilize DNA or RNA molecules to modulate abnormal gene expression or protein translation in cells, enabling precise treatment for specific conditions. In recent years, nucleic acid drugs have demonstrated tremendous potential in vaccine development and treating genetic disorders. Currently, the primary carriers for clinically approved nucleic acid therapies include lipid nanoparticles and viral vectors. Beyond that, metal-organic frameworks (MOFs) are highly ordered, porous nanomaterials formed through the self-assembly of metal ions and organic ligands via coordination bonds. Their porosity structure offers great loading efficiency, stability, tunability, and biocompatibility, making them an attractive option for nucleic acid delivery. Given the research on MOFs as nucleic acid carriers has garnered significant attention in recent years, this review provides an overview of the therapeutic strategies and advancements in MOF-mediated nucleic acid delivery. The unique properties of various MOF carriers are introduced, and different approaches for nucleic acid loading are parallelly compared. Moreover, a systematic classification based on the type of nucleic acid cargo loaded in MOFs and corresponding applications is thoroughly described. This summary outlines the unique mechanisms through MOFs enhance nucleic acid delivery and emphasizes their substantial impact on therapeutic efficacy. In addition, the utilization of MOF-mediated nucleic acid treatment in combination with other therapies against malignant tumors is discussed in particular. Finally, an outlook on the challenges and potential opportunities of this technology in future translational production and clinical implementation is presented and explored.

Engineered extracellular vesicles loaded in boronated cyclodextrin framework for pulmonary delivery

Extracellular vesicles (EVs) are promising therapeutic carriers for their ideal nano-size and intrinsic biocompatibility, while rapid clearance and limited targeting ability are the major setbacks of EVs. With minimal absorption into the systemic circulation, inhalation for pulmonary disease therapy minimizes off-target toxicity to other organs and offers a safe and effective treatment for respiratory disorders. Herein, a nano-grid carrier made of boronated cyclodextrin framework (BCF) was prepared for pH/H2O2 responsive release of EVs. A novel design of cyclo (Arg-Gly-Asp-D-Tyr-Lys) peptide (RGD)-modified milk-derived EVs (mEVs) loaded in the BCF particles (RGD-mEVs@BCF) was developed for pulmonary delivery. The results indicated that RGD-mEVs showed superior anti-inflammatory activity in contrast with mEVs in vitro. BCF was able to capture and protect RGD-mEVs, which showed extended-release profiles and responsiveness. Pulmonary administration of RGD-mEVs@BCF showed favorable biocompatibility in rats. Taken together, RGD-mEVs@BCF features biocompatibility and pH-responsive mEVs release as a therapeutic platform for pulmonary delivery of drugs to treat lung diseases, especially for inflammatory diseases.

Intercalated MOF nanocomposites: robust, fluorine-free and waterborne amphiphobic coatings

Transparent non-wetting surfaces with mechanical robustness are critical for applications such as contamination prevention, (anti-)condensation, anti-icing, anti-biofouling, etc. The surface treatments in these applications often use hazardous per- and polyfluoroalkyl substances (PFAS), which are bio-persistent or have compromised durability due to weak polymer/particle interfacial interactions. Hence, developing new approaches to synthesise non-fluorinated liquid-repellent coatings with attributes such as scalable fabrication, transparency, and mechanical durability is important. Here, we present a water-based spray formulation to fabricate non-fluorinated amphiphobic (repellent to both water and low surface tension liquids) coatings by combining polyurethane and porous metal-organic frameworks (MOFs) followed by post-functionalisation with flexible alkyl silanes. Owing to intercalation of polyurethane chains into MOF pores, akin to robust bicontinuous structures in nature, these coatings show excellent impact robustness, resisting high-speed water jets (∼35 m s-1), and a very low ice adhesion strength of ≤30 kPa across multiple icing/de-icing cycles. These surfaces are also smooth and highly transparent, and exhibit excellent amphiphobicity towards a range of low surface tension liquids from water to alcohols and ketones. The multi-functionality, robustness and potential scalability of our approach make this formulation a good alternative to hazardous PFAS-based coatings or solid particle/polymer nanocomposites.

MOF-KAN: Kolmogorov-Arnold Networks for Digital Discovery of Metal-Organic Frameworks

Digital discovery of functional materials, such as metal-organic frameworks (MOFs), entails accurate and data-efficient approaches to navigate complex chemical and structural space. Based on an innovative deep learning approach, namely, Kolmogorov-Arnold Networks (KANs), we introduce MOF-KAN, a state-of-the-art architecture as the first application of KANs to digital discovery of MOFs. Through meticulous fine-tuning of network architecture, we demonstrate that MOF-KAN outperforms standard multilayer perceptrons (MLPs) in predicting diverse properties for MOFs, including gas separation, electronic band gap, and thermal expansion. Furthermore, MOF-KAN excels in low-data regimes, facilitating robust performance in challenging prediction scenarios. Feature importance analysis reveals that MOF-KAN accurately captures critical features of MOFs relevant to targeted properties. MOF-KAN not only serves as a transformative tool for the rational design of functional materials but also holds broad applicability across various domains in physical sciences.

Enhancing Electron Donor-Acceptor Complex Photoactivation with a Stable Perylene Diimide Metal-Organic Framework

Electron donor-acceptor complexes are commonly employed to facilitate photoinduced radical-mediated organic reactions. However, achieving these photochemical processes with catalytic amounts of donors or acceptors can be challenging, especially when aiming to reduce catalyst loadings. Herein, we have unveiled a framework-based heterogenization approach that significantly enhances the photoredox activity of perylene diimide species in radical addition reactions with alkyl silicates by promoting faster and more efficient electron donor-acceptor complex formation. Besides offering broad substrate scope in alkene hydroalkylation, the newly developed heterogeneous photocatalysis substantially improves the catalyst turnover numbers in comparison to previous homogeneous photocatalytic systems and demonstrates outstanding catalyst recyclability. These research findings pave the way for the advancement of various efficient and practical organic transformations using framework-supported organocatalysts.

Exceeding flexpectations: a combined experimental and computational investigation of structural flexibility in 3-dimensional linker-based metal-organic frameworks

Designing sorbents for the separation of molecules with sub-angstrom differences in size requires precise control over pore size and environment, which can be challenging to establish in the presence of structural flexibility. However, metal-organic frameworks (MOFs) that incorporate 3-dimensional (3D) linkers-ditopic ligands with 3-dimensional, sterically bulky cores-are well-suited to address this challenge, as 3D linkers enable sub-angstrom level control over pore size by mitigating the effects of structural flexibility. In this study, we used a combined computational and experimental approach to quantify flexibility in two systems of MOFs with increasing linker bulkiness, leveraging these systems to distinguish between two classes of flexibility: global and local. Specifically, we used density functional theory (DFT) calculations to understand the electronic energy landscapes of MIL-53(Al), MIL-47(V) and their corresponding 3D linker analogues of increasing bulkiness. We further characterized the mechanical properties of these materials with DFT calculations of elastic tensors and in practical compression conditions using in situ variable pressure X-ray diffraction experiments. Finally, we illustrated the importance of establishing sub-angstrom level pore control by demonstrating the effects of each type of flexibility on the adsorption properties of MOFs using grand canonical Monte Carlo simulations.

A Semi-Interpenetrating Network Hydrogel with Excellent Photothermal Antibacterial and ROS Scavenging Activities for MRSA-Infected Wounds

The prolonged infection of bacteria at the wound site may lead to serious physical problems. Herein, a multifunctional macroporous hydrogel with superior photothermal antibacterial and ROS scavenging activity (denoted as M-XG gel) was designed for the treatment of MRSA-infected wounds. The M-XG gels are composed of embedding Prussian blue nanoparticles (PBNPs) as photothermal converters and chelating ferric ions with xanthan gum (XG) and dopamine (DA) to form a semipermeable network. The introduction of DA occupies the cross-link sites of ferric ions, further increasing the pore size (200-500 μm open macropores) and endowing the hydrogel with ideal adhesion. The increase of cross-link sites in PBNPs formed a promising equilibrium M-XG gel with identical macroporous structures and toughened mechanical performance. The metal ligands between ferric ions and catechols, as well as the unique photothermal response of PBNPs, endow the hydrogels with a fast and stable near-infrared (NIR) photothermal conversion efficiency (48%). In the MRSA-infected SD rat trauma model, wounds treated with the M-XG gel group had completely closed after 14 days, effectively controlling wound bacterial infection and accelerating angiogenesis and collagen deposition, synergistically promoting infected wound healing. Therefore, the photothermal hydrogel with a semi-interpenetrating network demonstrates its great potential for infected wound tissue engineering.

Electrospun Polyvinyl Chloride/UiO-66(COOH)2 Nanocomposite Membranes for Efficient and Rapid Heavy Metal Removal

This study explores the effectiveness of a new composite membrane fabricated from poly(vinyl chloride) (PVC) and the UiO-66(COOH)2 metal-organic framework (MOF) for the removal of heavy metals from water. The electrospinning technique was successfully employed to homogeneously incorporate UiO-66(COOH)2 nanocrystals into PVC, producing fibrous composite membranes. The membranes were fully characterized using several techniques such as scanning electron microscopy (SEM), capillary flow porometry, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), and tensile strength analysis. The metal removal performance of the membranes was evaluated against lead, cadmium, and mercury in both single and mixed metal solutions at different concentrations. Results indicated a high removal efficiency (>90%) and selectivity for lead in both single and mixed solutions, especially at concentrations less than 50 ppm, along with a high adsorption capacity (Qmax = 203 mg/g). While cadmium demonstrated a lower % removal efficiency of 40% in mixed solutions compared to 80% in single solutions, it exhibited the highest adsorption capacity (Qmax = 1312 mg/g) among the three metals. For mercury, however, the decrease in removal efficiency was more pronounced, with only 10% removal in mixed systems and the lowest adsorption capacity (Qmax = 40.5 mg/g). Further experiments showed that the presence of salts, such as chlorides, nitrates, and sulfates, did not significantly affect lead and cadmium removal. Conversely, mercury removal was consistently low, regardless of these conditions. Additionally, temperature-dependent studies revealed that increasing temperature enhanced both removal efficiency and adsorption capacity, confirming that the process was spontaneous and endothermic. Interestingly, the reusability of the membranes showed a consistent removal efficiency of over 90% for lead after four cycles of use, particularly at 15 ppm, although the other metals exhibited a decrease in efficiency. Almost all pollutants showed a better fit for Langmuir and second-order kinetic models, suggesting that adsorption is a single-layered chemical adsorption process. Furthermore, a membrane holder design was fabricated using three-dimensional (3D) printing and tested to underscore the potential of PVC/MOFs composite membranes as effective materials for efficient and rapid heavy metal remediation (5 mins) in contaminated water sources. The holder significantly improved lead removal efficiency while maintaining mechanical stability, addressing the issue of handling MOFs powder alone by providing a robust matrix and support for both the MOFs and the membrane. This approach facilitates easier handling while maintaining a high efficiency, paving the way for potential industrial applications.

Structural and Interfacial Characterization of a Photocatalytic Titanium MOF-Phosphate Glass Composite

Metal-organic framework (MOF) composites are proposed as solutions to the mechanical instability of pure MOF materials. Here, we present a new compositional series of recently discovered MOF-crystalline inorganic glass composites. In this case, formed by the combination of a photocatalytic titanium MOF (MIL-125-NH2) and a phosphate-based glass (20%Na2O-10%Na2SO4-70%P2O5). This new family of composites has been synthesized and characterized using powder X-ray diffraction, thermal gravimetric analysis, differential scanning calorimetry, scanning electron microscopy, and X-ray total scattering. Through analysis of the pair distribution function extracted from X-ray total scattering data, the atom-atom interactions at the MOF-glass interface are described. Nitrogen and carbon dioxide isotherms demonstrate good surface area values despite the pelletization and mixing of the MOF with a dense inorganic glass. The catalytic activity of these materials was investigated in the photooxidation of amines to imines, showing the retention of the photocatalytic effectiveness of the parent pristine MOF.

Teaching copolymerization catalysis to metal-organic frameworks by confining molecular catalysts in lattices

Copolymerization catalysis remains underexplored compared to the broad range of other catalytic reactions promoted by metal-organic frameworks (MOFs). Here, we report a lattice-confinement strategy that immobilizes a highly active molecular complex within MOFs, transforming them into effective heterogeneous catalysts for copolymerization-that couples cyclohexene oxide and CO2 into poly(cyclohexene carbonate) or integrates epoxide and phthalic anhydride into ester-ether copolymers. The encapsulated catalytically active species not only introduce new reaction patterns for MOFs but also enhance the structural robustness of the lattice, enabling the catalyst to be recycled multiple times.

Cu(II) Metal-Organic Framework as a Recyclable Heterogeneous Catalyst for Substituted Pyridine Synthesis from Cyclic Ketones with Propargylamine

The creation of efficient and stable metal-organic framework (MOF) catalysts with coordinatively unsaturated metal sites is critical in modern organic synthesis. Herein, we reported one new Cu(II)-MOF with the chemical formula of {[Cu(L)(H2O)]·2DMA·H2O}∞ (1) (H2L = 4,4'-((4R,5R)-4,5-diphenylimidazolidine-1,3-diyl)dibenzoic acid) for the annulation of cyclic ketones with propargylamine. Compound 1 possesses a 2-fold interpenetrating 3D kagome net with one channel opening of about 20 Å in diameter. Framework 1' exhibits high permanent porosity (778 m2/g, BET) and efficient recyclable catalytic activity for the annulation of cyclic ketones with propargylamine in a one-pot tandem reaction, affording a series of substituted pyridines in a good yield. X-ray photoelectron spectroscopy analysis indicates that Cu(II) is reduced to active Cu(I) species in the reaction system, while Cu(I) species selectively activate the triple bond to promote the annulation. The successful preparation of the heterogeneous Cu(II)-MOF presents new opportunities for developing highly active Cu catalysts for the annulation or other transformations mediated by Cu.

A Hydrolytically Stable Metal-Organic Framework for Simultaneous Desulfurization and Dehydration of Wet Flue Gas

Metal-organic frameworks (MOFs) have great prospects as adsorbents for industrial gas purification, but often suffer from issues of water stability and competitive water adsorption. Herein, we present a hydrolytically stable MOF that could selectively capture and recover trace SO2 from flue gas, and exhibits remarkable recyclability in the breakthrough experiments under wet flue-gas conditions, due to its excellent resistance to the corrosion of SO2 and the water-derived capillary forces. More strikingly, its SO2 capture efficiency is barely influenced by the increasing humidity, even if the pore filling with water is reached. Mechanistic studies demonstrate that the delicate pore structure with diverse pore dimensions and chemistry leads to different adsorption kinetics and thermodynamics as well as segregated adsorption domains of SO2 and H2O. Significantly, this non-competitive adsorption mechanism enables simultaneous desulfurization and dehydration by a single adsorbent, opening an avenue toward cost-effective and simplified processing flowcharts for flue gas purification.

A Facile Two-Step High-Throughput Screening Strategy of Advanced MOFs for Separating Argon from Air

Metal-organic frameworks (MOFs) based on the pressure swing adsorption (PSA) process show great promise in separating argon from air. As research burgeons, the number of MOFs has grown exponentially, rendering the experimental identification of materials with significant gas separation potential impractical. This study introduced a high-throughput screening through a two-step strategy based on structure-property relationships, which leveraged Grand Canonical Monte Carlo (GCMC) simulations, to swiftly and precisely identify high-performance MOF adsorbents capable of separating argon from air among a vast array of MOFs. Compared to traditional approaches for material development and screening, this method significantly reduced both experimental and computational resource requirements. This research pre-screened 12,020 experimental MOFs from a computationally ready experimental MOF (CoRE MOF) database down to 7328 and then selected 4083 promising candidates through structure-performance correlation. These MOFs underwent GCMC simulation assessments, showing superior adsorption performance to traditional molecular sieves. In addition, an in-depth discussion was conducted on the structural characteristics and metal atoms among the best-performing MOFs, as well as the effects of temperature, pressure, and real gas conditions on their adsorption properties. This work provides a new direction for synthesizing next-generation MOFs for efficient argon separation in labs, contributing to energy conservation and consumption reduction in the production of high-purity argon gas.

Verdazyl-Based Radicals for High-Field Dynamic Nuclear Polarization NMR

High-field dynamic nuclear polarization nuclear magnetic resonance (DNP NMR) spectroscopy transfers polarization from unpaired electrons in polarizing agents to nuclei of interest to boost NMR sensitivity. Verdazyl biradicals are a promising choice as polarizing agents because they have been found to generate narrower electron paramagnetic resonance (EPR) signals compared to nitroxide biradicals; an advantageous characteristic for high-field DNP when operating above 400 MHz/263 GHz. The use of verdazyl radicals as DNP polarizing agents has been very limited to date, yet, recent numerical simulations have predicted that verdazyl-nitroxide hybrid biradicals could be more effective polarizing agents than nitroxide-nitroxide biradicals. Herein, the syntheses of a series of verdazyl mono- and biradicals, as well as verdazyl-nitroxide biradicals are described. These radicals were examined in high-field DNP NMR experiments (600 MHz/395 GHz), by measuring 1H signal enhancements directly and through 13C{1H} cross-polarization experiments. X-band EPR, 1H DNP field profiles, and experiments to determine the nuclear build-up times were performed for verdazyl-nitroxide biradicals VerTEMPol and VerTEKol. These hybrid biradicals provide enhancements of up to 100-fold increased signal intensities (i.e., representing >104-fold time savings), approximately four times higher than that of the nitroxide biradical TEKPol, a commonly used polarizing agent in the field.

Manipulating Hydrogen-Bonding Donor/Acceptor in Ultra-Robust Isoreticular Zr(IV) Metal-Organic Frameworks for Efficient Regulation of Water Sorption Inflection Point and Steepness

The development of porous materials exhibiting steep and stepwise adsorption of water vapor at desired humidity is crucial for implementing diverse applications such as humidity control, heat allocation, and atmospheric water harvesting. The precise molecular-level elucidation of structural characteristics and chemical components that dictate the water sorption behaviors in confined nanospaces, metal-organic frameworks (MOFs) in particular, is fundamentally important, but this has yet to be largely explored. In this work, by leveraging the isoreticular principle, we crafted two pairs of isostructural Zr-MOFs with linker backbones of benzene and pyrazine acting as hydrogen-bonding donor and acceptor, respectively. The outstanding water sorption cyclic durability of the four Zr-MOFs permits persuasive investigation of the correlation of the water sorption inflection point and steepness (the two central figures-of-merit for water sorption) with the linker functionality. The two pyrazine-carrying Zr-MOFs both show steep water uptake at lower relative pressure and slightly decreased steepness, which are quantitatively described by the Dubinin-Astakhov relation. We deciphered the privileged water clusters through single-crystal X-ray diffraction studies in which the pyrazine moiety formed stronger hydrogen-bonding interactions with guest water molecules and favored the formation of water pentamers instead of hexamers that are observed in the benzene analog. The hydrogen-bonding donor/acceptor manipulation approach presented in this work may facilitate future research endeavors focusing on molecular attribute engineering in predeterminedly ultrawater-resistant MOF platforms for efficient regulation of water sorption behaviors toward customized applications.

Tuning the Crystallinity of a Metal-Organic Coordination Network at the Liquid-Solid Interface

Single layered metal-organic coordination networks (MOCNs) are gaining attention thanks to their unique electronic and magnetic properties. The presence of coordinatively unsaturated metal sites within their structures provides additional binding locations for substrates in catalytic processes. Consequently, MOCNs fabricated on solid surfaces are emerging as promising candidates for use in solution-based heterogeneous applications. The bottom-up synthesis of such surface-supported MOCNs requires a rigorous design by utilizing two-dimensional (2D) crystal engineering. However, a comprehensive description of the factors governing their synthesis at the liquid-solid interface is still missing, resulting in only a few reported examples. In this work, we use scanning tunneling microscopy (STM) at the liquid-solid interface to reveal the effect of the choice of solvent, concentration, and temperature on the structure of a surface-supported MOCN constituted by a tritopic ligand containing pyridyl moieties and trans-protected Pd(II) cations. A quantitative analysis of the network's crystallinity is presented. Furthermore, the impact of the synthetic pathway is investigated and a qualitative description of the growth mechanism is provided. Finally, the porosity of the extended honeycomb network is examined by studying the adsorption of guest molecules in its pores.

Engineering Helical Chirality in Metal-Coordinated Cyclodextrin Nanochannels

Helicates are a defining element of DNAs and proteins, with functions that are critical to a variety of biological processes. Cyclodextrins are promising candidates for forging multiple-stranded helicates with well-defined helicity, but a lack of available tools has precluded the construction of artificial helical nanochannels with a controllable geometry and helicity from these widely available chiral building blocks. Herein, we disclose a family of Ag6L2 helical nanochannels that can be readily assembled from α-cyclodextrin-derived ligands through coordination between pyridinyl groups and Ag+ cations. We discovered that the nanochannels exhibit either an M or a P helicity when the Ag+ cations adopt a tetrahedral coordination geometry while losing most of their helicity when the Ag+ cations are linearly coordinated. Both the geometry and helicity of the nanochannels can be precisely controlled by simply changing the number of methyl groups at the ortho positions of the pyridinyl ligands. The tetracoordinated Ag+ cations interconnect the helical nanochannels into an infinite two-dimensional coordinative network characterized by hexagonal tessellation. Theoretical calculations, which reveal lower energies of the helical conformations observed in crystals compared with those of their inverted counterparts, support the experimental results.

Non-van-der-Waals Oriented Two-Dimensional UiO-66 Films by Rapid Aqueous Synthesis at Room Temperature

The synthesis of MOFs in a two-dimensional (2D) film morphology is attractive for several applications including molecular and ionic separation. However, 2D MOFs have only been reported from structures that crystallize in lamellar morphology, where layers are held together by van der Waals (vdW) interaction. By comparison, UiO-66, one of the most studied MOFs because of its exceptional chemical stability, has only been reported in three-dimensional (3D) morphology. 2D UiO-66 is challenging to obtain given the robust isotropic bonds in its cubic crystal structure. Herein, we report the first synthesis of non-vdW 2D UiO-66-NH2 by developing crystal growth conditions that promote in-plane growth over out-of-plane growth. Continuous, oriented UiO-66-NH2 film with thickness tunable in the range of 0.5 to 2 unit cells could be obtained by sustainable, scalable chemistry, which yielded attractive ion-ion selectivity. The preparation of non-vdW 2D MOF is highly attractive to advance the field of MOF films for diverse applications.

Customized Controllable Pyrophosphate Nanosensor Based on Lanthanide Metal-Organic Frameworks for Accurate and Sensitive Detection of Nucleic Acids

Pyrophosphate (PPi) and nucleic acid amplification play a critical role in medical diagnostics, making the development of precise nanosensors essential. Lanthanide metal-organic frameworks (Ln-MOFs) are increasingly recognized for their potential in advanced luminescent biosensing applications. However, research on customized controllable responses in Ln-MOF nanosensors is still lacking, which is critical for the molecular-level modular design. In this work, we introduce a ligand engineering strategy to regulate coordination-induced antenna effect emission in Ln-MOFs, optimizing their pyrophosphate (PPi) sensing from fluorescence turn-off to turn-on modes. By tuning the coordination environment through ligand programming, we discovered a "near coordination compensation" effect, allowing for controllable transitions between aggregation-induced emission and quenching (AIE/AIQ). This reversible response was supported by density functional theory calculations. Using a Eu3+/Tb3+ dual-emission Ln-MOF designed with 2,6-pyridinedicarboxylic acid as the optimized ligand, we developed a self-correcting PPi nanosensor with a detection limit of 0.2 μM. Moreover, this system enabled ultrasensitive nucleic acid detection, achieving a limit of detection (LOD) as low as 1 fM, with applications in DNA pyrosequencing, qPCR, and DNA epigenetic modification (5-formylcytosine) analysis. These findings shed light on the structural and photophysical factors controlling Ln-MOF luminescence, offering a promising platform for highly accurate and sensitive nucleic acid detection in biomedical diagnostics.

Boosted recovery of rare earth elements from mining wastes and discarded NdFeB magnets by tributyl phosphate-grafted ZIF-8

The escalating demand for rare earth elements (REEs) highlights the necessity for their sustainable recovery from waste streams and secondary resources. However, this process requires materials with exceptional selectivity and capacity for REEs due to their low concentration and high presence of interfering ions. Herein, we synthesized zeolitic imidazolate framework-8 (ZIF-8) and subsequently modified it with tributyl phosphate (TBP) to enhance its affinity and selectivity for the recovery of REEs. The distribution coefficients (Kd) of ZIF-8-TBP for REEs (neodymium, Nd, and dysprosium, Dy) were orders of magnitude higher than the Kd of main interfering ions (e.g., Mg, Ni Al, and Fe). Particularly, the maximum sorption capacities (qm) for Nd and Dy were 475 and 529 mg g-1, respectively. In addition, the separation factor between Dy (a representative of heavy REE) and Nd (a representative of light REE) reached 24, greatly exceeding the figures reported previously. Importantly, the outstanding ability of ZIF-8-TBP for selective separation and recovery of REEs was demonstrated via its application to real samples including mining wastewater, and leaching solutions from REE filter cakes and discarded NdFeB magnets. Multiscale simulations reveal that ZIF-8-TBP possessed a stronger binding strength and greater sorption energy for REE ions. These results indicate that ZIF-8-TBP could effectively harvest REEs from wastes and offers an efficient alternative for industrial applications in REE recovery.

High-Nuclearity Polyoxometalate-Based Metal-Organic Frameworks for Photocatalytic Oxidative Cleavage of C-C Bond

High-nuclearity polyoxometalate (POM) clusters are attractive building blocks (BBs) for the synthesis of metal-organic frameworks (MOFs) due to their high connectivity and inherently multiple metal centers as functional sites. This work demonstrates a strategy of step-wise growth on ring-shaped [P8W48O184]40- precursor, which produced two new high-nuclearity polyoxotungstates, a half-closed [H16P8W58O218]32- {W58} and a fully-closed [H16P8W64O236]32- {W64}. By in situ synthesis, unique MOFs of copper triazole-benzoic acid (HL) complexes incorporating the negatively-charged {W58} and {W64} as nodes, {Cu11(HL)9W58} HNPOMOF-1 and {Cu9(HL)9W64} HNPOMOF-2, were constructed by delicately tuning the reaction conditions, mainly solution pH, which controls the formation of {W58} and {W64}, and at the same time the protonation of triazole-benzoic acid ligand thus its coordination mode to copper ion that creates the highest nuclearity POM-derived MOFs reported to date. HNPOMOF-1 features 3D framework possessing cage-like cavities filled with exposed carboxyl groups, while the inherent 2D layer-like HNPOMOF-2 allows for facile exfoliation into ultrathin nanosheets, and the resulted HNPOMOF-2NS exhibits superior activity towards photocatalytic oxidative cleavage of C-C bond for a series of lignin models. This work not only provides a strategy to build high-nuclearity POM cluster-based frameworks, but also demonstrates their great potential as functional materials for green catalysis.

Recent Advances on Integrating Porous Nanomaterials with Chemiluminescence Assays

Advanced porous nanomaterials have recently been the subject of considerable interest due to their high surface areas, tunable pore structures, high porosity, and ease of modification. In the chemiluminescence (CL) domain, the incorporation of additional pores into nanostructures not only enhances the loading capacity for signal amplification but also allows the confinement effect in a nanoscale microreactor and the controlled release of reaction agents. In light of this, increasing efforts have been made to fabricate various porous nanomaterials and explore their potential applications in CL assays. This review therefore aims to highlight the recent advances in preparation strategies and basic attributes of the CL-related porous nanomaterials. Moreover, it offers a comprehensive summary of the emerging CL sensing applications based on these materials. The key challenges and future perspectives of porous nanomaterials in CL assays are finally discussed.

Post-Synthetic Modification of a MOF via Continuous Flow Methods for Gold E-Waste Recycling

This work represents a pioneering effort in utilizing continuous flow methods for the post-synthetic modification of a nanoporous metal-organic framework (Fe-BTC or MIL-100(Fe)) with short-chain redox-active oligomers (poly-p-phenylenediamine, PpPDA). The Fe-BTC/PpPDA composite has been previously demonstrated to rapidly and selectively extract gold from complex liquids. Thus, in the present study, Fe-BTC/PpPDA was synthesized on a 250 g scale and tested in eight industrially relevant solutions used for leaching metals from electronic waste. These leachates (e. g., cyanide, thiourea, and aqua regia) exhibited varying effectiveness, pH, and gold speciation, which led to significant differences in the composite's performance during gold extraction. Notably, Fe-BTC/PpPDA performed best in leaching solutions containing [AuCl4]- species. Subsequently, Fe-BTC/PpPDA was structured into spherical beads using a novel microdroplet technique in continuous flow. These structured adsorbents were then placed in a column and assessed for gold recovery from real e-waste solutions containing [AuCl4]- species. The composite reached a capacity of ~600 mg of gold per gram before breakthrough and a capacity of ~900 mg of gold per gram at a gold recovery rate of ~60 %. The selectivity of the composite was calculated to be 972, 262, and 193 for Au/Ni, Au/Co, and Au/Fe, respectively. Also, in situ X-ray absorption near edge spectroscopy (XANES) was employed to monitor the gold oxidation state, providing the first evidence of gold reduction occurring on a timescale relevant to flow-through experiments. It was confirmed that the redox-active oligomers facilitate the reduction of Au3+ to metallic Au during extraction, enhancing the composite's capacity and selectivity. Additionally, Fe-BTC/PpPDA outperformed several commercial resins commonly used in gold recovery. Considering the scalability of the composite and its outstanding performance in realistic solutions, this work suggests a promising future for MOF/polymer composites in selective metal recovery from waste streams. Furthermore, the continuous flow methods used for post-synthetic modification of the MOF may pave the way for more scalable production in the future.

Exploring the Potential of Metal-Organic Frameworks as Reverse Osmosis Membranes for Water Desalination

Water desalination via reverse osmosis (RO) to produce fresh water represents an ideal solution to address water shortage. Membranes of large water permeability and high salt rejection are desired, and these properties are subject to the design of the membrane structure. The structural tunability of metal-organic frameworks (MOFs) therefore provides tremendous opportunities, but their potential has not yet been systematically explored. In this study, molecular dynamics simulations are conducted to investigate MOFs with a focus on a subclass of water stable Zirconium-based MOFs as RO membranes in water desalination. The results show that MOF membranes can indeed achieve a perfect salt rejection while allowing notably high permeability as compared to commercial polymeric membranes. Moreover, the structure-performance relationship is explored, and the critical role of channel homogeneity is identified. Overall, the outcomes of this study demonstrate the great promise of MOFs and provide guidelines on the selection and design of MOFs for effective and efficient water desalination.

Photosynthesis-Inspired NIR-Triggered Fe₃O₄@MoS₂ Core-Shell Nanozyme for Promoting MRSA-Infected Diabetic Wound Healing

Bacterial infections can lead to severe medical complications, including major medical incidents and even death, posing a significant challenge in clinical trauma repair. Consequently, the development of new, efficient, and non-resistant antimicrobial agents has become a priority for medical practitioners. In this study, a stepwise hydrothermal reaction strategy is utilized to prepare Fe3O4@MoS2 core-shell nanoparticles (NPs) with photosynthesis-like activity for the treatment of bacterial infections. The Fe3O4@MoS2 NPs continuously catalyze the production of reactive oxygen species (ROS) from hydrogen peroxide through photosynthesis-like reactions and convert light energy into heat with a photothermal efficiency of 30.30%. In addition, the photosynthetically generated ROS, combined with the iron-induced cell death mechanism of the Fe3O4@MoS2 NPs, confer them with exceptional and broad-spectrum antibacterial properties, achieving antimicrobial activities of up to 98.62% for Staphylococcus aureus, 99.22% for Escherichia coli, and 98.55% for methicillin-resistant Staphylococcus aureus. The composite exhibits good cell safety and hemocompatibility. Finally, a full-thickness diabetic wound model validates the significant pro-healing properties of Fe3O4@MoS2 in chronic diabetic wounds. Overall, the design of photosynthesis-inspired Fe3O4@MoS2 presents new perspectives for developing efficient photothermal nano-enzymatic compounds, offering a promising solution to the challenges of antimicrobial drug resistance and antibiotic misuse.

An apparatus for preparing frozen solution samples in ultrahigh vacuum experiments

Here, we develop an apparatus for preparing frozen solution samples, which can be characterized by surface science techniques under ultrahigh vacuum (UHV) conditions. When a temperature-controlled substrate makes contact with a frozen solution at 77 K, the surface of the frozen solution is locally melted and then refreezes together with the substrate. By detaching the substrate from the frozen solution in situ in a high vacuum, the frozen solution is cleaved and transferred onto the substrate. Applying this method, we demonstrate transferring NaCl and LiNO3 frozen solutions onto an Au substrate and directly imaging the crystallization of NaCl and LiNO3 with atomic resolution using atomic force microscopy (AFM) in UHV at 5 K. This apparatus provides a new approach to transfer solution samples in their glassy states into the UHV environment while maintaining the cleanliness of the samples, laying the foundation for further research related to the solution environment in real life, such as crystallization, hydration, chemical reaction, materials synthesis, and bioimaging.

Biomineralize Mitochondria in Metal-Organic Frameworks to Promote Mitochondria Transplantation From Non-Tumorigenic Cells Into Cancer Cells

Mitochondria are crucial to cellular physiology, and growing evidence highlights the significant impact of mitochondrial dysfunction in diabetes, aging, neurodegenerative disorders, and cancers. Therefore, mitochondrial transplantation shows great potential for therapeutic use in treating these diseases. However, transplantation process is notably challenging due to very low efficiency and rapid loss of bioactivity post-isolation, leading to poor reproducibility and reliability. In this study, we develop a novel strategy to form a nanometer-thick protective shell around isolated mitochondria using Metal-Organic Frameworks (MOFs) through biomineralization. Our findings demonstrate that this encapsulation method effectively maintains mitochondria bioactivity for at least 4 weeks at room temperature. Furthermore, the efficiency of intracellular delivery of mitochondria is significantly enhanced through the surface functionalization of MOFs with polyethyleneimine (PEI) and the cell-penetrating peptide Tat. The successful delivery of mitochondria isolated from non-tumorigenic cells into cancer cells results in notable tumor-suppressive effects. Taken together, our technology represents a significant advancement in mitochondria research, particularly on understanding their role in cancer. It also lays the groundwork for utilizing mitochondria as therapeutic agents in cancer treatment.

Immobilization of β-glucosidase and β-xylosidase on inorganic nanoparticles for glycosylated substances conversion

There are abundant glycosylated substances such as cellulose, hemicellulose, and phytochemical glycosides in plants, which could be converted into functional chemicals such as monosaccharides, oligosaccharides, and bioactive aglycones by cleavage of glycosidic bonds using glycoside hydrolases (GHs). Among those GHs, β-glucosidase and β-xylosidase are the rate-limiting enzymes for degrading cellulose and hemicellulose, respectively, and can convert a variety of glycosylated substances. These two enzymes play important roles in the high value use of plant resources and have great potential applications. However, the fragility of enzymes suggests there is an urgent need to improve the activity, stability and reusability of GHs under industrial conditions. Enzyme immobilization is an efficient approach to meet the need. Inorganic materials are preferred carriers for enzyme immobilization, since they possess high surface area, pore size, stability and long service life. Recently, many reports have showed that GHs immobilized on inorganic materials exhibit potential applications on industry and will benefit the process economy. The present review provides an overview of these reports from the perspectives of materials, strategies, activities, stability and reusability, as well as an insight into the related mechanisms, with a view to providing a reference for the GHs immobilization and their applications.

Integrating Humidity-Resistant and Colorimetric COF-on-MOF Sensors with Artificial Intelligence Assisted Data Analysis for Visualization of Volatile Organic Compounds Sensing

Direct visualization and monitoring of volatile organic compounds (VOCs) sensing processes via portable colorimetric sensors are highly desired but challenging targets. The key challenge resides in the development of efficient sensing systems with high sensitivity, selectivity, humidity resistance, and profuse color change. Herein, a strategy is reported for the direct visualization of VOCs sensing by mimicking human olfactory function and integrating colorimetric COF-on-MOF sensors with artificial intelligence (AI)-assisted data analysis techniques. The Dye@Zeolitic Imidazolate Framework@Covalent Organic Framework (Dye@ZIF-8@COF) sensor takes advantage of the highly porous structure of MOF core and hydrophobic nature of the COF shell, enabling highly sensitive colorimetric sensing of trace number of VOCs. The Dye@ZIF-8@COF sensor exhibits exceptional sensitivity to VOCs at sub-parts per million levels and demonstrates excellent humidity resistance (under 20-90% relative humidity), showing great promise for practical applications. Importantly, AI-assisted information fusion and perceptual analysis greatly promote the accuracy of the VOCs sensing processes, enabling direct visualization and classification of seven stages of matcha drying processes with a superior accuracy of 95.74%. This work paves the way for the direct visualization of sensing processes of VOCs via the integration of advanced humidity-resistant sensing materials and AI-assisted data analyzing techniques.