Redox-active metal-organic frameworks (MOFs) are very promising materials due to their potential capabilities for postsynthetic modification aimed at tailoring their application properties. However, the research field related to redox-active MOFs is still relatively underdeveloped, which limits their practical application. We investigated the self-assembly process of Cr(II) ions and isophthalate (m-bdc) linkers, which have been previously demonstrated to yield 0D metal-organic polyhedra. However, using the diffusion-controlled synthetic approach, we demonstrate the selective preparation of a 2D-layered Cr(II)-based MOF material [Cr(m-bdc)]·H2O (1·H2O). Remarkably, the controlled oxidation of the developed 2D MOF using nitric oxide or dry oxygen resulted in modified porous materials with excellent H2/N2 adsorption selectivities.

Metal-organic frameworks (MOFs) provide an extensive design landscape for nanoporous materials that drive innovation across energy and environmental fields. However, their practical applications are often hindered by water stability challenges. In this study, a machine learning (ML) approach is proposed to accelerate the discovery of water stable MOFs and validated through experimental test. First, the largest database currently available that contains water stability information of 1133 synthesized MOFs is constructed and categorized according to experimental stability. Then, structural and chemical descriptors are applied at various fragmental levels to develop ML classifiers for predicting the water stability of MOFs. The ML classifiers achieve high prediction accuracy and excellent transferability on out-of-sample validation. Next, two MOFs are experimentally synthesized with their water stability tested to validate ML predictions. Finally, the ML classifiers are applied to discover water stable MOFs in the ab initio REPEAT charge MOF (ARC-MOF) database. Among ≈280 000 candidates, ≈130 000 (47%) MOFs are predicted to be water stable; furthermore, through multi-stability analysis, 461 (0.16%) MOFs are identified as not only water stable but also thermal and activation stable. The ML approach is anticipated to serve as a prerequisite filtering tool to streamline the exploration of water stable MOFs for important practical applications.

Per- and polyfluoroalkyl substances (PFAS) in water requires sufficient removal due to their extreme chemical stability and potential health risk. Membrane separation can be a promising strategy, while membranes with conventional structures used for PFAS removal often face challenges such as limited efficiency and stability. In this study, a novel metal-organic framework (MOF) membrane with local modification of polyamide (PA) was developed by introducing interfacial polymerization process during the construction of lamellar membranes with MOF nanosheets. Benefiting from the dense structure and strong negative surface charge, the PA-modified MOF membrane could effectively remove 11 types of PFAS (five short-chain and six long-chain ones with molecular weights ranging from 214.0 to 514.1 Da), especially displaying high rejections for short-chain PFAS (over 84%), along with a remarkable water permeance of 21.4 L·m⁻²·h⁻¹·bar⁻1. The membrane removal characteristics for PFAS were deeply analyzed by elucidating various rejection mechanisms, with particularly distinguishing the rejection and adsorption capacity. Moreover, the membrane stability was significantly enhanced, demonstrated by the structural integrity after 10 min of ultrasonic treatment and stable separation efficiency over 120 h of continuous filtration. With enhanced surface hydrophilicity and negative charge as well as dense membrane pores, the novel membrane also exhibited more superior anti-fouling performance compared to conventional lamellar and PA membranes, further manifesting advantages for practical applications. This work provides a promising solution for developing high-performance membranes tailored specifically for efficient PFAS removal, addressing a critical need in water treatment.

A refined electrochemical aptamer sensing technique using PEI@Ti-MOF@Ti3C2Tx-MXene was developed for the sensitive detection of ZEN in food samples. A titanium-based metal-organic skeleton (NH2-MIL-125) was synthesized in situ using 2-aminoterephthalic acid as the organic ligand and tetrabutyl titanate as the metal center, followed by the simultaneous hybridization of Ti3C2Tx-MXene to synthesize a Ti-MOF@Ti3C2Tx-MXene composite material. These composites were subsequently functionalized with PEI and covalently linked to form a sensing platform on gold electrodes. Integrating a metal-organic framework (MOF) with MXene materials not only improved the electrochemical properties compared to those of individual elements but also decreased the stacking effect and increased the number of binding sites for the aptamer. The limit of detection (LOD) of this sensor was 1.64 fg mL-1. Additionally, the sensor could efficaciously detect ZEN in cornmeal and beer samples, exhibiting outstanding stability, reproducibility, and selectivity. This highlighted its effectiveness in applications in quality supervision and food safety.

A metal-organic frameworks (MOFs)-in-MOF nanovehicle (160 nm), which was constructed with newly prepared ultrasmall Cu(I)Cu(II)-BTC MOFs (UCMs, 2.95 nm) loaded with doxorubicin (DOX) and a nuclear localization signal (NLS) peptide as multicores (UCMDNs) and ZIF-8 as the shell MOF, was proposed to cross layers of biological barriers with adaptive size evolution capacity for achieving efficient nucleus-targeted drug delivery. It first enhanced tumor tissue penetration through its larger nanosize effect. Then the acidic tumor environment made the ZIF-8 shell degrade, releasing small-sized UCMDNs to enter into the cell and into the nucleus under the guidance of NLS. Furthermore, due to the distinct surface structural characteristics of UCMs, UCMDNs remained stable in the cytoplasm and collapsed in the nucleus due to the DOX-DNA interaction to deliver DOX precisely. It showed superior performance in the nucleus-directed delivery of DOX (delivery efficiency up to 56.7%) and a high tumor growth inhibition rate (96.4%), offering promising prospects in tumor chemotherapy.

The confinement effect of porous materials on the thermodynamical equilibrium of the CO2 hydrogenation reaction presents a cost-effective alternative to transition metal catalysts. In metal-organic frameworks, the type of metal center has a greater impact on the enhancement of formic acid production than the scale of confinement resulting from the pore size. The M-MOF-74 series enables a comprehensive study of how different metal centers affect HCOOH production, minimizing the effect of pore size. In this work, molecular simulations were used to analyze the adsorption of HCOOH and the CO2 hydrogenation reaction in M-MOF-74, where M = Ni, Cu, Co, Fe, Mn, Zn. We combine classical simulations and density functional theory calculations to gain insights into the mechanisms that govern the low coverage adsorption of HCOOH in the surrounding of the metal centers of M-MOF-74. The impact of metal centers on the HCOOH yield was assessed by Monte Carlo simulations in the grand-canonical ensemble, using gas-phase compositions of CO2, H2, and HCOOH at chemical equilibrium at 298.15-800 K, 1-60 bar. The performance of M-MOF-74 in HCOOH production follows the same order as the uptake and the heat of HCOOH adsorption: Ni > Co > Fe > Mn > Zn > Cu. Ni-MOF-74 increases the mole fraction of HCOOH by ca. 105 times compared to the gas phase at 298.15 K, 60 bar. Ni-MOF-74 has the potential to be more economically attractive for CO2 conversion than transition metal catalysts, achieving HCOOH production at concentrations comparable to the highest formate levels reported for transition metal catalysts and offering a more valuable molecular form of the product.

Metal-organic frameworks (MOFs) are composite crystalline materials created through the coordination of metal ions and organic ligands. MOFs have attracted extensive attention in the biomedical field based on the advantages of internal porosity, customizable porosity, and facile surface modification. This review examines the utilization of MOFs in drug delivery systems, focusing on the research progress from the aspects of coloading drug systems, intelligent responsive carriers, biological macromolecule stabilizers, self-driving micro/nanomotors, and multifunctional living carriers. In addition, the current challenges the research faces are also discussed. The review aims to provide a reference for the further application of MOFs as advanced drug delivery systems.

We report a systematic analysis of electron beam damage of the zeolitic imidazolate framework (ZIF-8) during liquid cell transmission electron microscopy (LCTEM). Our analysis reveals ZIF-8 morphology is strongly affected by solvent used (water vs dimethylformamide), electron flux applied, and imaging mode (i.e., TEM vs STEM), while ZIF-8 crystallinity is primarily affected by accumulated electron fluence. Our observations indicate that the stability of ZIF-8 morphology is higher in dimethylformamide (DMF) than in water. However, in situ electron diffraction indicates that ZIF-8 nanocrystals lose crystallinity at critical fluence of ∼80 e-Å-2 independent of the presence of solvent. Furthermore, 4D-STEM analysis as a post-mortem method reveals the extent of electron beam damage beyond the imaging area and indicates that radiolytic reactions are more pronounced in TEM mode than in STEM mode. These results illustrate the significance of radiolysis occurring while imaging ZIF-8 and present a workflow for assessing damage in LCTEM experiments.

The recovery of gold from industrial effluents is crucial for environmental conservation, sustainable resource management, and promoting the green development of gold resources. We designed a Zr-based MOF (UKM-78) by incorporating functional organic ligands that resemble amino groups, using MOFs\' inherent sieving effect for ion separation. This novel material exhibited enhanced gold recovery under acidic conditions, with an adsorption capacity three times and an adsorption rate four times higher than those of nonfunctionalized UKM-77. Notably, UKM-78 efficiently captured gold solutions at concentrations as low as 1 ppm and achieved an adsorption rate exceeding 90%, owing to the electrostatic interactions and coordination between its functionalized groups and the synergistic effect of its porous structure. Despite multiple regeneration cycles, UKM-78 retains 99.4% of its adsorption capacity. X-ray photoelectron spectroscopy (XPS), kinetic studies, and thermodynamics collectively demonstrated that Au(III) binding on UKM-78 involved cooperative electrostatic interactions and chemical adsorption through coordination. This study highlights the potential of MOFs for efficient and sustainable recovery of gold from complex waste streams.

The separation of acetylene (C2H2) from ethylene (C2H4) and ethane (C2H6) is crucial for the production of high-purity C2H2 and the recovery of other gases. Polyhedron-based metal-organic frameworks (PMOFs) are characterized by their spacious cavities, which facilitate gas trapping, and cage windows with varying sizes that enable gas screening. In this study, we carefully selected a class of PMOFs based on V-type tetracarboxylic acid linker (JLU-Liu22 containing benzene ring, JLU-Liu46 containing urea group and recombinant reconstructed In/Cu CBDA on the basis of JLU-Liu46) to study the relationship between pore environment and C2 adsorption and separation performance. Among the three compounds, JLU-Liu46 exhibits superior selectivity toward C2H2/C2H4 (2.06) as well as C2H2/C2H6 (2.43). Comparative structural analysis reveals that the exceptional adsorbed-C2H2 performance of JLU-Liu46 can be attributed to the synergistic effects arising from coordinatively unsaturated Cu sites combined with an optimal pore environment (matched pore size and polarity, urea functional group), resulting in a strong affinity between the framework and C2H2 molecules. Furthermore, transient breakthrough simulations of JLU-Liu46 confirmed its potential for separating C2H2 in ternary C2 gas.