Metal-organic Framework Composites Research Articles

Toward Selective Transport of Monovalent Metal Ions with High Permeability Based on Crown Ether-Encapsulated Metal-Organic Framework Sub-Nanochannels.

Achieving selective transport of monovalent metal ions with high precision and permeability analogues to biological protein ion channels has long been explored for fundamental research and various applications, such as ion sieving, mineral extraction, and energy harvesting and conversion. However, it still remains a significant challenge to construct artificial nanofluidic devices to realize the trade-off effects between selective ion transportation and high ion permeability. In this work, we report a bioinspired functional micropipet with in situ growth of crown ether-encapsulated metal-organic frameworks (MOFs) inside the tip and realize selective transport of monovalent metal ions. The functional ion-selective micropipet with sub-nanochannels was constructed by the interfacial growth method with the formation of composite MOFs consisting of ZIF-8 and 15-crown-5. The resulting micropipet device exhibited obvious monovalent ion selectivity and high flux of Li+ due to the synergistic effects of size sieving in subnanoconfined space and specific coordination of 15-crown-5 toward Na+. The selectivity of Li+/Na+, Li+/K+, Li+/Ca2+, and Li+/Mg2+ with 15-crown-5@ZIF-8-functionalized micropipet reached 3.9, 5.2, 105.8, and 122.4, respectively, which had an obvious enhancement compared to that with ZIF-8. Notably, the ion flux of Li+ can reach up to 93.8 ± 3.6 mol h-1·m-2 that is much higher than previously reported values. Furthermore, the functional micropipet with 15-crown-5@ZIF-8 sub-nanochannels exhibited stable Li+ selectivity under various conditions, such as different ion concentrations, pH values, and mixed ion solutions. This work not only provides new opportunities for the development of MOF-based nanofluidic devices for selective ion transport but also facilitates the promising practical applications in lithium extraction from salt-like brines, sewage treatment, and other related aspects.

Nonenzymatic dual glucose sensing on boronic acid modified zeolitic imidazolate framework-67 nanoparticles for diabetes management.

For early diabetes identification and management, the progression of an uncomplicated and exceedingly responsive glucose testing technology is crucial. In this study, we present a new sensor incorporating a composite of metal organic framework (MOF) based on cobalt, coated with boronic acid to facilitate selective glucose binding. Additionally, we successfully employed a highly sensitive electro-optical immunosensor for the detection of subtle changes in concentration of the diabetes biomarker glycated haemoglobin (HbA1c), using zeolitic imidazolate framework-67 (ZIF-67) coated with polydopamine which further modified with boronic acid. Utilizing the polymerization characteristics of dopamine and the NH2 groups, a bonding structure is formed between ZIF-67 and 4-carboxyphenylboronic acid. ZIF-67 composite served as an effective substrate for immobilising 4-carboxyphenylboronic acid binding agent, ensuring precise and highly selective glucose identification. The sensing response was evaluated through both electrochemical and optical methods, confirming its efficacy. Under optimized experimental condition, the ZIF-67 based sensor demonstrated a broad detection range of 50-500mg dL-1, a low limit of detection (LOD) of 9.87mg dL-1 and a high correlation coefficient of 0.98. Furthermore, the 4-carboxyphenylboronic acid-conjugated ZIF-67-based sensor platform exhibited remarkable sensitivity and selectivity in optical-based detection for glycated haemoglobin within the clinical range of 4.7-11.3%, achieving a LOD of 3.7%. These findings highlight the potential of the 4-carboxyphenylboronic acid-conjugated ZIF-67-based electro-optical sensor as a highly sensitive platform for diabetes detection.

Copper/cobalt metal-organic framework composites for advanced anode material of lithium-ion battery

In this paper, two new types of metal-organic frameworks (MOFs) materials, namely Cu-IM and Co-MOF, have been successfully applied to the anode of lithium-ion batteries with LiPF6 (EC: DMC = 1:1, volume) electrolyte additive. Cu-IM and Co-MOF employed imidazole (IM) and 2-methylimidazole (2-MeIM) as organic ligands, respectively. The results revealed the synthesized MOFs exhibited high initial discharge specific capacities (Cu-IM: 1964.5 mAh g−1, Co-MOF: 1423.3 mAh g−1) as well as low internal resistances (Cu-IM: 146 Ω; Co-MOF: 236 Ω). To alleviate the issue of capacity decay in single MOFs, we attempted the dual-MOFs materials through the rational design of interfacial/surface properties and microstructure. Compared to Cu-IM, the prepared Cu-IM/Co-MOF composites have a higher specific surface area and pore volume. Furthermore, the charge transfer resistance of Cu-IM/Co-MOF composites (141 Ω) was lower than that of Cu-IM and Co-MOF respectively. After a heat treatment to Cu-IM/Co-MOF composites, the electrochemical performance of obtained Cu-IM/Co-MOF 250 dual-MOFs composites have been significantly improved. The Cu-IM/Co-MOF 250 dual-MOFs composites demonstrated excellent cycling stability and high discharge specific capacities at various current densities. The composites displayed stable discharge specific capacity retention of 834 mAh g−1 (50 mA g−1, 75 cycles), 710.5 mAh g−1 (200 mA g−1, 50 cycles), and 392.5 mAh g−1 (500 mA g−1, 50 cycles), highlighting their promising performance for energy storage applications. The synthesized Cu-IM/Co-MOF 250 dual-MOFs composites demonstrates exceptional cycling performance and rate capability, implying that it has the promising prospects as anode material for lithium-ion batteries.

Enzyme_Metal-Organic Framework Composites as Novel Approach for Microplastic Degradation.

Plastic pollution is one of the main worldwide environmental concerns. Our lifestyle involves persistent plastic consumption, aggravating the low efficiency of wastewater treatment plants in its removal. Nano/microplastics are accumulated in living beings, pushing to identify new water remediation strategies to avoid their harmful effects. Enzymes (e.g.,Candida rugosa-CrL) are known natural plastic degraders as catalysts in depolymerization reactions. However, their practical use is limited by their stability, recyclability, and economical concerns. Here, enzyme immobilization in metal-organic frameworks (CrL_MOF) is originally presented as a new plastic degradation approach to achieve a boosted plastic decomposition in aqueous systems while allowing the catalyst cyclability. Bis-(hydroxyethyl)terephthalate (BHET) was selected as model substrate for decontamination experiments for being the main polyethylene terephthalate (PET) degradation product. Once in contaminated water, CrL_MOFs can eliminate BHET (37%, 24h), following two complementary mechanisms: enzymatic degradation (CrL action) and byproducts adsorption (MOF effect). As aproof-of-concept, the capacity of a selected CrL_MOF composite to eliminate the BHET degradation products and its reusability are also investigated. The potential of these systems is envisioned in terms of improving enzyme cyclability, reducing costs along with feasible co-adsorption of plastic byproducts and other harmful contaminants, to successfully remove themin a single step.

PdRu Bimetallic Nanoparticles/Metal-Organic Framework Composite through Supercritical CO2-Assisted Immobilization.

Metal-nanoparticle (NP)/metal-organic framework (MOF) composites have attracted considerable attention as heterogeneous catalysts. Compared with porous carbon, silica, and alumina, the charge-transfer interaction between the metal NPs and the MOF accelerated the catalytic activity. In this study, PdRu bimetallic NPs were successfully immobilized on MOFs such as MIL-101(Cr) by using supercritical carbon dioxide. The STEM-EDX images show a uniform 3D distribution of the PdRu bimetallic NPs on MIL-101(Cr). The resulting PdRu@MIL-101(Cr) catalyst exhibited higher CO oxidation than monometal/MOF composites such as Pd@MIL-101(Cr) and Ru@MIL-101(Cr). Furthermore, PdRu@MIL-101(Cr) exhibited higher catalytic activity than PdRu@SiO2. This is because the particle size of the PdRu bimetallic NPs in MIL-101(Cr) was within the range of 2-3 nm. The synergistic effects were based on the combination of two metals, Pd and Ru, small bimetal particle formation, and charge-transfer interactions between the bimetal NPs and the MOF. These factors enhance the catalytic activity of the bimetal/MOF composites.

Porphyrin Metal-organic Framework Sensors for Chemical and Biological Sensing.

Porphyrins and porphyrin derivatives have been intensively explored for a number of applications such as sensing, catalysis, adsorption, and photocatalysis due to their outstanding photophysical properties. Their usage in sensing applications, however, is limited by intrinsic defects such as physiological instability and self-quenching. To reduce self-quenching susceptibility, researchers have developed porphyrin metal-organic frameworks (MOFs). Metal-organic frameworks (MOFs), a unique type of hybrid porous coordination polymers comprised of metal ions linked by organic linkers, are gaining popularity. Porphyrin molecules can be integrated into MOFs or employed as organic linkers in the production of MOFs. Porphyrin-based MOFs are a separate branch of the huge MOF family that combines the distinguishing qualities of porphyrins (e.g., fluorescent nature) and MOFs (e.g., high surface area, high porosity) to enable sensing applications with higher sensitivity, specificity, and extended target range. The key synthesis techniques for porphyrin-based MOFs, such as porphyrin@MOFs, porphyrinic MOFs, and composite porphyrinic MOFs, are outlined in this review article. This review article focuses on current advances and breakthroughs in the field of porphyrin-based MOFs for detecting a variety of targets (for example, metal ions, anions, explosives, biomolecules, pH, and toxins). Finally, the issues and potential future uses of this class of emerging materials for sensing applications are reviewed.

Biomimetic spray coating for fruit preservation based on UiO-1 67 metal–organic framework nanozyme

The application of edible coatings for preparing composite antibacterial spray coatings for fruit preservation by incorporating antibacterial nanoparticles has gained increasing attention. Chitosan (CS) is a natural polysaccharide used as an edible coating to preserve fruit; it has properties such as reducing water loss, enhancing appearance, and improving mechanical properties. By combining it with antibacterial material, it can reduce fruit microorganisms. Cerium (Ce) has excellent antibacterial activity combined with the advantages of safety and low cost. Therefore, this study proposes a biocatalytic spray coating for fruit preservation using a CS composite metal–organic framework (CS@Ce-MOF) with strawberry as a model fruit. CS@Ce-MOFs are superior to Ce-MOFs in the aqueous stability of their chemical structure, inoxidizability, antibacterial duration, and validity. The well-characterized CS@Ce-MOF was verified to simultaneously mimic good oxidase- and apyrase-like activities. CS@Ce-MOF biocatalytic spray coating demonstrated excellent antibacterial properties against two common foodborne pathogens: Escherichia coli and the Gram-positive bacterium Staphylococcus aureus, with high killing rates of up to 94.5%. This is due to the unique structure of the CS@Ce-MOF composite, which presents a large surface area for contact with pathogens and enhances the catalytic activity of the incorporated cerium oxide nanoparticles, leading to efficient sterilization. Furthermore, the scavenging rate of DPPH and ABTS free radicals is more than 80%, indicating that CS@Ce-MOF has excellent antioxidant properties. Moreover, CS@Ce-MOF minimized the weight loss and firmness of strawberries and bananas over 7 days of ambient storage. The use of such a biocatalytic spray coating has enormous potential for preserving the quality and safety of fresh produce, reducing food waste, and promoting sustainable agricultural practices.

Synthesis of rare earth MOF/CZS materials derived from aromatic tetracarboxylic acids and photocatalytic hydrogen production

With the increasing urgency of clean energy, photocatalytic hydrogen production serves as a sustainable hydrogen manufacturing method to improve the increasing scarcity of fossil fuels and environmental pollution. Herein, Cd0.2Zn0.8S (CZS)-modified Metal-Organic Framework (MOF) composites Pr–NO2–TPTC/CZS were successfully prepared through the reaction of Pr3+, aromatic tetracarboxylic acid, and Cd0.2Zn0.8S nanoparticles. Pr–NO2–TPTC/CZS composite materials exhibited enhanced photolysis performance compared to pure Pr–NO2–TPTC and Cd0.2Zn0.8S materials. With the decrease of Cd0.2Zn0.8S in Pr–NO2–TPTC/CZS composites, the photocatalytic performance of the synthesized composites is constantly improved. Pr–NO2–TPTC/CZS (1:1) photocatalyst exhibited excellent hydrogen evolution performance, with a hydrogen production capacity of 6321 μmol g−1 h−1. Photoluminescence spectroscopy (PL), photocurrent-time test (I-t), and electrochemical impedance spectroscopy (EIS) confirmed that the heterojunction interface formed between Pr–NO2–TPTC and CZS promoted electron-hole separation and transfer. Electron paramagnetic resonance (EPR) indicated that CZS-modified Pr–NO2–TPTC can promote the production of ·OH and ·O2− in the system, thereby increasing the photocatalytic hydrogen production performance. This work provides an effective solution for photocatalytic hydrogen production and a potential method for solving the energy crisis and environmental pollution.

Recent advances in small-angle scattering techniques for MOF colloidal materials

This paper reviews the recent progress of small angle scattering (SAS) techniques, mainly including X-ray small angle scattering technique (SAXS) and neutron small angle scattering (SANS) technique, in the study of metal-organic framework (MOF) colloidal materials (CMOFs). First, we introduce the application research of SAXS technique in pristine MOFs materials, and review the studies on synthesis mechanism of MOF materials, the pore structures and fractal characteristics, as well as the spatial distribution and morphological evolution of foreign molecules in MOF composites and MOF-derived materials. Then, the applications of SANS technique in MOFs are summarized, with emphasis on SANS data processing method, structure modeling and quantitative structural information extraction. Finally, the characteristics and developments of SAS techniques are commented and prospected. It can be found that most studies on MOF materials with SAS techniques focus mainly on nanoporous structure characterization and the evolution of pore structures, or the spatial distribution of other foreign molecules loaded in MOFs. Indeed, SAS techniques take an irreplaceable role in revealing the structure and evolution of nanopores in CMOFs. We expect that this paper will help to understand the research status of SAS techniques on MOF materials and better to apply SAS techniques to conduct further research on MOF and related materials.

Core–shell MOF@COF composites for ultra-efficient selective recovery of Pd(II)

Developing efficient and selective recovery of Pd(II) adsorbents is crucial for addressing environmental pollution issues. Among them, covalent organic framework (COF) and metal organic framework (MOF) composites due to the multi-site functional groups are expected to exhibit excellent Pd(II) adsorption. However, the design and preparation of COF and MOF composite adsorbents for highly efficient adsorption of heavy metal Pd(II) still face many challenges. Herein, we constructed a series of novel core–shell structure UiO-66-NH2@TAP-COF (denoted as M@C) adsorbents (M@C-X, X = 1–5, representing different MOF doses) by Schiff base reaction and applied in the adsorption of Pd(II). The findings indicated that the M@C-3 exhibited ultra-high adsorption performance, reaching a capacity of 2134.1 mg/g, and displayed excellent selectivity, making it the best among similar materials. Experimental data and density functional theory (DFT) calculations revealed that the efficient and selective adsorption of Pd(II) is attributed to coordination interaction and strong electrostatic between Pd(II) and the abundant N and O groups in M@C. This work demonstrates the significant potential of the constructed core–shell M@C composites for the efficient and selective recovery of precious metal Pd(II).

Highly electrically conductive MOF/conducting polymer nanocomposites toward tunable electromagnetic wave absorption

Metal-organic frameworks (MOFs) have attracted significant interest as self-templates and precursors for the synthesis of carbon-based composites aimed at electromagnetic wave (EMW) absorption. However, the utilization of high-temperature treatments has introduced uncertainties regarding the compositions and microstructures of resulting derivatives. Additionally, complete carbonization has led to diminished yields of the produced carbon composites, significantly limiting their practical applications. Consequently, the exploration of pristine MOF-based EMW absorbers presents an intriguing yet challenging endeavor, primarily due to inherently low electrical conductivity. In this study, we showcase the utilization of structurally robust Zr-MOFs as scaffolds to build highly conductive Zr-MOF/PPy composites via an inner-outer dual-modification approach, which involves the production of conducting polypyrrole (PPy) both within the confined nanoporous channels and the external surface of Zr-MOFs via post-synthetic modification. The interconnection of confined PPy and surface-lined PPy together leads to a consecutive and extensive conducting network to the maximum extent. This therefore entails outstanding conductivity up to ∼14.3 S cm−1 in Zr-MOF/PPy composites, which is approximately 1-2 orders of magnitude higher than that for conductive MOF nanocomposites constructed from either inner or outer modification. Benefiting from the strong and tunable conduction loss, as well as the induced dielectric polarization originated from the porous structures and MOF-polymer interfaces, Zr-MOF/PPy exhibits excellent microwave attenuation capabilities and a tunable absorption frequency range. Specifically, with only 15 wt.% loading, the minimum reflection loss (RLmin) can reach up to -67.4 dB, accompanied by an effective absorption bandwidth (EAB) extending to 6.74 GHz. Furthermore, the microwave absorption characteristics can be tailored from the C-band to the Ku-band by adjusting the loading of PPy. This work provides valuable insights into the fabrication of conductive MOF composites by presenting a straightforward pathway to enhance and regulate electrical conduction in MOF-based nanocomposites, thus paving a way to facilely fabricate pristine MOF-based microwave absorbers.

Efficient Adsorption of Methylene Blue Using a Hierarchically Structured Metal-Organic Framework Derived from Layered Double Hydroxide.

The growing concerns about environmental pollution, particularly water pollution, are causing an increasing alarm in modern society. One promising approach to address this issue involves engineering existing materials to enhance their effectiveness. A one-step solvothermal reconstruction approach was used to build an eco-friendly two-dimensional (2D) AlNiZn-LDH/BDC MOF composite. The characterizations confirm the formation of a metal-organic framework (MOF) at the layered double hydroxide (LDH) surface. The resulting synthesized material, 2D AlNiZn-LDH/BDC MOF, demonstrated remarkable efficacy in decontaminating methylene blue (MB), a model cationic dye found in water systems. The removal performance of 2D AlNiZn-LDH/BDC MOF was significantly higher than that of pristine 2D AlNiZn-LDH. This improvement shows the potential to increase the adsorption capabilities of nanoporous LDH materials by incorporating organic ligands and integrating meso-/microporosity through MOF formation on their surfaces. Furthermore, their kinetic, isothermal, and thermodynamic studies elucidated the adsorption behavior of this composite material. The results of synthesized MOF showed excellent removal efficiency (92.27%) of 10 ppm of MB aqueous solution as compared to pristine LDH. Additionally, the as-synthesized adsorbent could be regenerated for six successive cycles. This method holds promise for the synthesis of novel and highly effective materials to combat water pollution, laying the groundwork for potential advancements in diverse applications.

Puissant synergistic effect between g-C3N4 and MIL-100(Fe) for highly stable enhanced activation of H2O2 to degrade antibiotic tetracycline hydrochloride

The release of antibiotics in the environment has raised concerns about ecological damage and human health. As a promising technology, Fenton-like processes have been extensively studied to degrade pollutants in water and achieve rapid and efficient removal. Composites of metal-organic frameworks (MOFs) and graphitic carbon nitride (g-C3N4) have shown excellent performance in Fenton-like processes as a potent combination. However, there is a lack of similar studies to confirm their outstanding catalytic performance and stability in catalyzing the H2O2 process. Therefore, to complete the research in this field and to explore the efficient removal of antibiotics, composites of g-C3N4 and MIL-100(Fe) (CNMIL-x) were fabricated by post-synthesis for highly efficient H2O2 activation to remove tetracycline hydrochloride (TC-HCl). Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) show that the characteristic morphology and peaks of g-C3N4 and MIL-100(Fe) varied according to the mass ratio between them. According to X-ray photoelectron spectroscopy (XPS), Fe is primarily in the Fe(Ⅲ) state. Besides, CNMIL-1.5 shows a SBET value of 598.46 m2·g−1, a Vpore of 0.42 cm3·g−1, and a pore size of 7.31 nm, which are significantly enhanced compared with g-C3N4. During TC-HCl degradation, the degradation rate of CNMIL-1.5 (0.02772 min−1) is 9.1 and 1.8 times faster compared to that of g-C3N4 and MIL-100(Fe), respectively. Furthermore, the excellent stability of CNMIL-1.5 are demonstrated by the quintuple cyclic experiments and characterization. A possible degradation mechanism dominated by •OH as well as a relative pathway of TC-HCl removal are proposed.

Introducing sulfonic acid polymers into MOF nanochannels for ultra-high Ba2+ adsorption capacity and proton conductivity

Porous materials with a high concentration of sulfonic acid groups are highly desirable for applications such as radioactive Ba2+ adsorption, catalysis, and proton-conductive materials, but they are also challenging to synthesize. In this work, we introduce polymers containing sulfonic acid groups into the nanochannels of metal–organic frameworks (MOFs) through in-situ synthesis to enhance the sulfonic acid content. We use a alkene with sulfonic acid groups (2)-acrylamido-2-methylpropane sulfonic acid, AMPS) and a crosslinking agent N,N’-methylenebisacrylamide (MBAA) to synthesize two MOF composites, PAMPS@MIL-101 and PAMPS@MIL-101-SO3H, in the ultra-stable MIL-101 series through in-situ polymerization with free radical initiators. The two MOF composites have a high and uniform distribution of sulfonic acid groups in the MOF framework, which results in ultra-high barium ion adsorption capacity. The maximum adsorption amounts are 142.7 and 356.9 mg·g−1 for PAMPS@MIL-101 and PAMPS@MIL-101-SO3H, respectively, which are higher than those of most reported adsorbents. Importantly, the adsorption equilibrium can be achieved within 20 min. Moreover, both MOF composites, PAMPS@MIL-101 and PAMPS@MIL-101-SO3H, exhibit super proton conductivity, with values of 6.43 × 10−2 S·cm−1 and 1.43 × 10−1 S·cm−1 at 85 °C and 98 % RH, respectively. This method offers a new way of modifying MOF nanochannels with high sulfonic acid concentrations, and opens up new opportunities for developing radioactive Ba2+ adsorption materials and proton-conductive materials.

Rare [Cu4I2]2+ cationic cluster-based metal-organic framework and hierarchical porous composites design for effective detection and removal of roxarsone and antibiotics

Fluorescence quenching induced by photoinduced electron transfer (PET) stands as an effective strategy for identifying water pollutants. Herein, a novel (4, 8)-connected three-dimensional framework Cu(I)-MOF ([Cu2I(tpt)]n) with unique 8-connected [Cu4I2]2+ cationic clusters is designed by employing the nitrogen-rich ligand (Htpt = 5-[4(1H-1,2,4-triazol-1-yl)]phenyl-2H-tetrazole). Water-stabilized Cu(I)-MOF exhibits outstanding fluorescence properties, facilitating its application in detecting organic pollutants in water. Benefiting from the fact that the Cu(I)-MOF possesses a higher lowest unoccupied molecular orbitals (LUMO) energy level than that of the analyte, the rapid d-PET can occur, entitling Cu(I)-MOF to a sensitive fluorescence quenching response to roxarsone (ROX), nitrofurazone (NFZ) and nitrofurantoin (NFT) (with detection limits as low as 0.13 µM, 0.15 µM, and 0.13 µM, respectively). The nitrogen-containing sites of melamine foam (MF) are utilized to facilitate the anchoring and growth of Cu-MOF crystals, which enables the preparation of hierarchical microporous − macroporous Cu(I)-MOF/MF composites. The ordered porous structure of Cu(I)-MOF/MF provides cavities and open sites for the efficient removal of ROX (qmax = 210.6 mg∙g−1), NFZ (qmax = 111.5 mg∙g−1) and NFT (qmax = 238.9 mg∙g−1) from water. This characteristic endows the Cu(I)-MOF/MF with rapid and recyclable adsorption capacity. Therefore, this work provides valuable insights to address the problem of detection and removal of pollutants in the aquatic environment.

Molecularly imprinted metal-organic frameworks assisted cloth and paper hybrid microfluidic devices for visual detection of gonyautoxin

Marine algal toxin contamination is a major threat to human health. Thus, it is crucial to develop rapid and on-site techniques for detecting algal toxins. In this work, we developed colorimetric cloth and paper hybrid microfluidic devices (μCPADs) for rapid detection of gonyautoxin (GTX1/4) combined with molecularly imprinted polymers. In addition, the metal-organic frameworks (MOFs) composites were applied for this approach by their unique features. Guanosine serves as a dummy template for surface imprinting and has certain structural advantages in recognizing gonyautoxin. MOF@MIPs composites were able to perform a catalytic color reaction using hydrogen peroxide-tetramethylbenzidine for the detection of GTX1/4. The cloth-based sensing substrates were assembled on origami μPADs to form user-friendly, miniaturized colorimetric μCPADs. Combined with a smartphone, the proposed colorimetric μCPADs successfully achieved a low limit of detection of 0.65 μg/L within the range of 1–200 μg/L for rapid visual detection of GTX1/4. Moreover, the GTX1/4 of real shellfish and seawater samples were satisfactorily detected to indicate the application prospect of the μCPADs. The proposed method shows good potential in the low-cost, stable establishment of assays for the rapid detection of environmental biotoxins.

Just Soaping Them: The Simplest Method for Converting Metal Organic Frameworks into Superhydrophobic Materials.

The incorporation of superhydrophobic properties into metal organic framework (MOF) materials is highly desirable to enhance their hydrolytic stability, gas capture selectivity in the presence of humidity and efficiency in oil-water separations, among others. The existing strategies for inducing superhydrophobicity into MOFs have several weaknesses, such as increased cost, utilization of toxic reagents and solvents, applicability for limited MOFs, etc. Here, we report the simplest, most eco-friendly, and cost-effective process to impart superhydrophobicity to MOFs, involving a rapid (90 min) treatment of MOF materials with solutions of sodium oleate, a main component of soap. The method can be applied to both hydrolytically stable and unstable MOFs, with the porosity of modified MOFs approaching, in most cases, that of the pristine materials. Interestingly, this approach was used to isolate superhydrophobic magnetic MOF composites, and one of these materials formed stable liquid marbles, whose motion could be easily guided using an external magnetic field. We also successfully fabricated superhydrophobic MOF-coated cotton fabric and fiber composites. These composites exhibited exceptional oil sorption properties achieving rapid removal of floating crude oil from water, as well as efficient purification of oil-in-water emulsions. They are also regenerable and reusable for multiple sorption processes. Overall, the results described here pave the way for an unprecedented expansion of the family of MOF-based superhydrophobic materials, as virtually any MOF could be converted into a superhydrophobic compound by applying the new synthetic approach.

Enantiomeric analysis of chiral phenyl aromatic compounds by coated capillary electrochromatography based on aMOF-on-MOF stationary phase.

Chiral phenyl aromatic compounds (CPACs) are widely used in drug development, food/cosmetic production, and other organic synthesis processes, and their different enantiomers have distinct physiological activities and application differences. A double-layer metal-organic framework composite (MOF-on-MOF) was obtained by in situ synthesis of chiral metal-organic framework (CMOM-3S) on the surface of an iron-based metal-organic framework (NH2-MIL-101(Fe)). According to ourinvestigation, MOF-on-MOF composite was for the first time applied tothe stationary phase of capillary electrochromatography (CEC), and enantioseparations of eight CPACs were accomplished. Compared with single CMOM-3S, the enantioseparation performance of the coated capillary columns based on NH2-MIL-101(Fe)@CMOM-3S was improved by 34.07 ~ 720.0%. The R-/S-mandelic acid in actual sample (apricot leaves) was detected by the newly CEC system to be 0.0118mgmL-1 and 0.0523mgmL-1, respectively. The spike recoveries were 96.60 ~ 104.7%, indicating its good stability and accuracy. In addition, the selective adsorption capacity of MOF-on-MOF composites was verified by adsorption experiments.

Crystalline porous materials for catalytic conversion of lignin‐related substances

AbstractThe conversion of the biomass into eco‐friendly fuels and chemicals has been extensively recognized as the essential pathway to achieve the sustainable economy and carbon neutral society. Lignin, as a kind of promising biomass energy, has been certified to produce the high‐valued chemicals and fuels. Numerous efforts have been made to develop various catalysts for lignin catalytic conversion. Both metal‐organic frameworks (MOFs) and covalent organic frameworks (COFs) belong to very important heterogeneous porous catalysts due to their regular porous structures, high specific surface area, and precisely tailored diversities. In the review, the first part focused on the catalytic conversion of lignin, lignin model compounds, and lignin derivatives using the pristine MOFs, functional MOF composites, and MOF‐derived materials. The second part summarized the catalytic conversion of lignin model compounds using pristine COFs and functional COF composites. The review here mainly concentrated on the design of the materials, screening of catalytic conditions, and explorations of the corresponded mechanisms. Specifically, (1) we summarized the MOF‐ and COF‐based materials for the effects on the catalytic transformation of lignin‐related substances; (2) we emphasized the catalytic mechanism of C–C and C–O bonds cleavage together with the structure–activity relationships; (3) we in‐depth realized the relationship between the chemical/electronic/structural properties of the MOF‐ and COF‐based catalysts and their catalytic performance for lignin‐related substances. Finally, the challenges and future perspectives were also discussed on the catalytic conversion of lignin‐related substances by MOF‐ and COF‐based catalysts.

Metal-Organic Framework-Based Nanomaterials for Regulation of the Osteogenic Microenvironment.

As the global population ages, bone diseases have become increasingly prevalent in clinical settings. These conditions often involve detrimental factors such as infection, inflammation, and oxidative stress that disrupt bone homeostasis. Addressing these disorders requires exogenous strategies to regulate the osteogenic microenvironment (OME). The exogenous regulation of OME can be divided into four processes: induction, modulation, protection, and support, each serving a specific purpose. To this end, metal-organic frameworks (MOFs) are an emerging focus in nanomedicine, which show tremendous potential due to their superior delivery capability. MOFs play numerous roles in OME regulation such as metal ion donors, drug carriers, nanozymes, and photosensitizers, which have been extensively explored in recent studies. This review presents a comprehensive introduction to the exogenous regulation of OME by MOF-based nanomaterials. By discussing various functional MOF composites, this work aims to inspire and guide the creation of sophisticated and efficient nanomaterials for bone disease management.