Creating Lithium‐Ion Electrolytes with Biomimetic Ionic Channels in Metal–Organic Frameworks

Solid‐state electrolytes are the key to the development of lithium‐based batteries with dramatically improved energy density and safety. Inspired by ionic channels in biological systems, a novel class of pseudo solid‐state electrolytes with biomimetic ionic channels is reported herein. This is achieved by complexing the anions of an electrolyte to the open metal sites of metal–organic frameworks (MOFs), which transforms the MOF scaffolds into ionic‐channel analogs with lithium‐ion conduction and low activation energy. This work suggests the emergence of a new class of pseudo solid‐state lithium‐ion conducting electrolytes.     

Confined Heteropoly Blues in Defected Zr‐MOF (Bottle Around Ship) for High‐Efficiency Oxidative Desulfurization

The Keggin‐type polyoxometalates (POMs) are effective catalysts for oxidative desulfurization (ODS) and confining these POMs in metal–organic frameworks (MOFs) is a promising strategy to improve their performances. Herein, postsynthetic modification of POMs confined in MOFs by adding thiourea creates more unsaturated metal sites as defects, promoting ODS catalytic activity. Additional modification by confining 1‐butyl‐3‐methyl imidazolium POMs in MOFs is performed to obtain higher ODS activity, owing to the affinity between electron‐rich thiophene‐based compounds and electrophilic imidazolium compounds. The ODS catalytic activities of four Zr‐MOF‐based composites (bottle around ship) including phosphomolybdate acid (PMA)/UiO‐66, [Bmim]₃PMo₁₂O₄₀/UiO‐66, PMA/Thiourea/UiO‐66, and [Bmim]₃PMo₁₂O₄₀/Thiourea/UiO‐66 are therefore investigated in detail. In order to explore the catalytic mechanism of these MOF composites, their microstructures and electronic structures are probed by various techniques such as X‐ray diffraction, thermogravimetric analysis, Fourier transform infrared, Raman, scanning electron microscope, transmission electron microscope, BET, X‐ray photoelectron spectroscopy, EPR, UV–vis, NMR spectra, and H₂‐temperature‐programmed reduction. The results reveal that phosphomolybdate blues and imidazolium phosphomolybdate blues with different Mo⁵⁺/Mo⁶⁺ ratios with the Keggin structure are confined in defected UiO‐66 for all four composites. This approach can be applied to design and synthesize other POMs/MOFs composites as efficient catalysts.     

Highly Adsorptive,MOF‐Functionalized Nonwoven Fiber Mats for Hazardous Gas Capture Enabled by Atomic Layer Deposition

While metal‐organic frameworks (MOFs) show great potential for gas adsorption and storage, their powder form limits deployment opportunities. Integration of MOFs on polymeric fibrous scaffolds will enable new applications in gas adsorption, membrane separation, catalysis, and toxic gas sensing. Here, we demonstrate a new synthesis route for growing MOFs on fibrous materials that achieves high MOF loadings, large surface areas and high adsorptive capacities. We find that a nanoscale coating of Al₂O₃ formed by atomic layer deposition (ALD) on the surface of nonwoven fiber mats facilitates nucleation of MOFs on the fibers throughout the mat. Functionality of MOFs is fully maintained after integration, and MOF crystals are well attached to the fibers. Breakthrough tests for HKUST‐1 MOFs [Cu₃(BTC)₂] on ALD‐coated polypropylene fibers reveal NH₃ dynamic loadings up to 5.93 ± 0.20 mol/kg_(MOF+fiber). Most importantly, this synthetic approach is generally applicable to a wide range of polymer fibers (e.g., PP, PET, cotton) and MOFs (e.g., HKUST‐1, MOF‐74, and UiO‐66).     

Super‐Stable,Highly Efficient,and Recyclable Fibrous Metal–Organic Framework Membranes for Precious Metal Recovery from Strong Acidic Solutions

Precious metals such as palladium (Pd) and platinum (Pt) are marvelous materials in the fields of electronic and catalysis, but they are tapering day by day. Zr(IV)‐based metal–organic frameworks (MOFs) are competent for their recovery, notably in harsh environments, while the general powder form limits their practical application. Porous MOF‐based membranes with ultraefficient metal ion permeation, strong stability, and high selectivity are, therefore, strikingly preferred. Herein, a set of polymeric fibrous membranes incorporated with the UiO‐66 series are fabricated; their adsorption/desorption capabilities toward Pd(II) and Pt(IV) are evaluated from strongly acidic solutions; and the MOF–polymer compatibilities are investigated. Polyurethane (PU)/UiO‐66‐NH₂ showed strong acid resistance and high chemical stability, which are attributable to strong π–π interactions between PU and MOF nanoparticles with a high configuration of energy. The as‐fabricated MOF membranes show extremely good adsorption/desorption performances without ruptures/coalitions of nanofibers or leak of MOF nanoparticles, and successfully display the efficacy in a gravity‐driven or even continuous‐flow system with good recycle performance and selectivity. The as‐fabricated MOF membranes set an example of potential MOF–polymer compatibility for practical applications.     

Water‐Stable Chemical‐Protective Textiles via Euhedral Surface‐Oriented 2D Cu–TCPP Metal‐Organic Frameworks

Abatement of chemical hazards using adsorptive metal‐organic frameworks (MOFs) attracts substantial attention, but material stability and crystal integration into functional systems remain key challenges. Herein, water‐stable, polymer fiber surface–oriented M–TCPP [M = Cu, Zn, and Co; H₂TCPP = 5,10,15,20‐tetrakis(4‐carboxyphenyl)porphyrin] 2D MOF crystals are fabricated using a facile hydroxy double salt (HDS) solid‐source conversion strategy. For the first time, Cu–TCPP is formed from a solid source and confirmed to be highly adsorptive for NH₃ and 2‐chloroethyl ethyl sulfide (CEES), a blistering agent simulant, in humid (80% relative humidity (RH)) conditions. Moreover, the solid HDS source is found as a unique new approach to control MOF thin‐film crystal orientation, thereby facilitating radially arranged MOF crystals on fibers. On a per unit mass of MOF basis in humid conditions, the MOF/fiber composite enhances NH₃ adsorptive capacity by a factor of 3 compared to conventionally prepared MOF powders. The synthesis route extends to other MOF/fiber composite systems, therefore providing a new route for chemically protective materials.     

Self‐Template‐Directed Metal–Organic Frameworks Network and the Derived Honeycomb‐Like Carbon Flakes via Confinement Pyrolysis

Metal–organic frameworks (MOFs) have become a research hotspot since they have been explored as convenient precursors for preparing various multifunctional nanomaterials. However, the preparation of MOF networks with controllable flake morphology in large scale is not realized yet. Herein, a self‐template strategy is developed to prepare MOF networks. In this work, layered double‐metal hydroxide (LDH) and other layered metal hydroxides are used not only as a scaffold but also as a self‐sacrificed metal source. After capturing the abundant metal cations identically from the LDH by the organic linkers, MOF networks are in situ formed. It is interesting that the MOF network‐derived carbon materials retain the flake morphology and exhibit a unique honeycomb‐like macroporous structure due to the confined shrinkage of the polyhedral facets. The overall properties of the carbon networks are adjustable according to the tailored metal compositions in LDH and the derived MOFs, which are desirable for target‐oriented applications as exemplified by the electrochemical application in supercapacitors.     

Flexible Metal–Organic Framework‐Based Mixed‐Matrix Membranes: A New Platform for H2S Sensors

Metal–organic framework (MOF)–polymer mixed‐matrix membranes (MMMs) have shown great potential and superior performance in gas separations. However, their sensing application has not been fully established yet. Herein, a rare example of using flexible MOF‐based MMMs as a fluorescent turn‐on sensor for the detection of hydrogen sulfide (H₂S) is reported. These MOF‐based MMMs are readily prepared by mixing a highly stable aluminum‐based nano‐MOF (Al‐MIL‐53‐NO₂) into poly(vinylidene fluoride) with high loadings up to 70%. Unlike the intrinsic fragility and poor processability of pure‐MOF membranes, these MMMs exhibit desirable flexibility and processability that are more suitable for practical sensing applications. The uniform distribution of Al‐MIL‐53‐NO₂ particles combined with the permanent pores of MOFs enable these MMMs to show good water permeation flux and consequently have a full contact between the analyte and MOFs. The developed MMM sensor (70% MOF loading) thus shows a highly remarkable detection selectivity and sensitivity for H₂S with an exceptionally low detection limit around 92.31 × 10^?9m , three orders of magnitude lower than the reported powder‐form MOFs. This work demonstrates that it is feasible to develop flexible luminescent MOF‐based MMMs as a novel platform for chemical sensing applications.     

Ultrafine Silver Nanoparticles Embedded in Cyclodextrin Metal‐Organic Frameworks with GRGDS Functionalization to Promote Antibacterial and Wound Healing Application

The challenge of bacterial infection increases the risk of mortality and morbidity in acute and chronic wound healing. Silver nanoparticles (Ag NPs) are a promising new version of conventional antibacterial nanosystem to fight against the bacterial resistance in concern of the drug discovery void. However, there are several challenges in controlling the size and colloidal stability of Ag NPs, which readily aggregate or coalesce in both solid and aqueous state. In this study, a template‐guided synthesis of ultrafine Ag NPs of around 2 nm using water‐soluble and biocompatible γ‐cyclodextrin metal‐organic frameworks (CD‐MOFs) is reported. The CD‐MOF based synthetic strategy integrates AgNO₃ reduction and Ag NPs immobilization in one pot achieving dual functions of reduced particle size and enhanced stability. Meanwhile, the synthesized Ag NPs are easily dispersible in aqueous media and exhibit effective bacterial inhibition. The surface modification of cross‐linked CD‐MOF particles with GRGDS peptide boosts the hemostatic effect that further enhances wound healing in synergy with the antibacterial effect. Hence, the strategy of ultrafine Ag NPs synthesis and immobilization in CD‐MOFs together with GRGDS modification holds promising potential for the rational design of effective wound healing devices.     

State‐of‐the‐Art Advances and Challenges of Iron‐Based Metal Organic Frameworks from Attractive Features,Synthesis to Multifunctional Applications

Metal organic frameworks (MOFs), as an original kind of organic–inorganic porous material, are constructed with metal centers and organic linkers via a coordination complexation reaction. Among uncountable MOF materials, iron‐containing metal organic frameworks (Fe‐MOFs) have excellent potential in practical applications owing to their many fascinating properties, such as diverse structure types, low toxicity, preferable stability, and tailored functionality. Here, recent research progresses of Fe‐MOFs in attractive features, synthesis, and multifunctional applications are described. Fe‐MOFs with porosity and tailored functionality are discussed according to the design of building blocks. Four types of synthetic methods including solvothermal, hydrothermal, microwave, and dry gel conversion synthesis are illustrated. Finally, the applications of Fe‐MOFs in Li‐ion batteries, sensors, gas storage, separation in gas and liquid phases, and catalysis are elucidated, focusing on the mechanism. The aim is to provide prospects for extending Fe‐MOFs in more practical applications.     

Emerging Multifunctional Metal–Organic Framework Materials

Metal?organic frameworks (MOFs), also known as coordination polymers, represent an interesting type of solid crystalline materials that can be straightforwardly self‐assembled through the coordination of metal ions/clusters with organic linkers. Owing to the modular nature and mild conditions of MOF synthesis, the porosities of MOF materials can be systematically tuned by judicious selection of molecular building blocks, and a variety of functional sites/groups can be introduced into metal ions/clusters, organic linkers, or pore spaces through pre‐designing or post‐synthetic approaches. These unique advantages enable MOFs to be used as a highly versatile and tunable platform for exploring multifunctional MOF materials. Here, the bright potential of MOF materials as emerging multifunctional materials is highlighted in some of the most important applications for gas storage and separation, optical, electric and magnetic materials, chemical sensing, catalysis, and biomedicine.     

Constructing Connected Paths between UiO‐66 and PIM‐1 to Improve Membrane CO2 Separation with Crystal‐Like Gas Selectivity

Most metal–organic‐framework‐ (MOF‐) based hybrid membranes face the challenge of low gas permeability in CO₂ separation. This study presents a new strategy of interweaving UiO‐66 and PIM‐1 to build freeways in UiO‐66‐CN@sPIM‐1 membranes for fast CO₂ transport. In this strategy, sPIM‐1 is rigidified via thermal treatment to make polymer voids permanent, and concurrently polymer chains are mutually linked onto UiO‐66‐CN crystals to minimize interfacial defects. The pore chemistry of UiO‐66‐CN is kept intact in hybrid membranes, allowing full utilization of MOF pores and selective adsorption for CO₂. Separation results show that UiO‐66‐CN@sPIM‐1 membranes possess exceptionally high CO₂ permeability (15433.4–22665 Barrer), approaching to that of UiO‐66‐NH₂ crystal (65–75% of crystal‐derived permeability). Additionally, the CO₂/N₂ permeation selectivity for a representative membrane (23.9–28.6) moves toward that of single crystal (24.6–29.6). The unique structure and superior CO₂/N₂ separation performance make UiO‐66‐CN@sPIM‐1 membranes promising in practical CO₂ separations.     

Metal–Organic‐Framework‐Based Catalysts for Photoreduction of CO2

Photoreduction of CO₂ into reusable carbon forms is considered as a promising approach to address the crisis of energy from fossil fuels and reduce excessive CO₂ emission. Recently, metal–organic frameworks (MOFs) have attracted much attention as CO₂ photoreduction‐related catalysts, owing to their unique electronic band structures, excellent CO₂ adsorption capacities, and tailorable light‐absorption abilities. Recent advances on the design, synthesis, and CO₂ reduction applications of MOF‐based photocatalysts are discussed here, beginning with the introduction of the characteristics of high‐efficiency photocatalysts and structural advantages of MOFs. The roles of MOFs in CO₂ photoreduction systems as photocatalysts, photocatalytic hosts, and cocatalysts are analyzed. Detailed discussions focus on two constituents of pure MOFs (metal clusters such as Ti–O, Zr–O, and Fe–O clusters and functional organic linkers such as amino‐modified, photosensitizer‐functionalized, and electron‐rich conjugated linkers) and three types of MOF‐based composites (metal–MOF, semiconductor–MOF, and photosensitizer–MOF composites). The constituents, CO₂ adsorption capacities, absorption edges, and photocatalytic activities of these photocatalysts are highlighted to provide fundamental guidance to rational design of efficient MOF‐based photocatalyst materials for CO₂ reduction. A perspective of future research directions, critical challenges to be met, and potential solutions in this research field concludes the discussion.     

Shape‐Defined Hollow Structural Co‐MOF‐74 and Metal Nanoparticles@Co‐MOF‐74 Composite through a Transformation Strategy for Enhanced Photocatalysis Performance

In recent years, metal–organic frameworks (MOFs) have received extensive interest because of the diversity of their composition, structure, and function. To promote the MOFs' function and performance, the construction of hollow structural metal–organic frameworks and nanoparticle–MOF composites is significantly effective but remains a considerable challenge. In this article, a transformation strategy is developed to synthesize hollow structural Co‐MOF‐74 by solvothermal transformation of ZIF‐67. These Co‐MOF‐74 particles exhibit a double‐layer hollow shell structure without remarkable shape change compared to original ZIF‐67 particles. The formation of hollow structure stemmed from the density difference of Co between ZIF‐67 and Co‐MOF‐74. By this strategy, hollow structural Co‐MOF‐74 with different sizes and shapes are obtained from corresponding ZIF‐67, and metal nanoparticles@Co‐MOF‐74 is synthesized by corresponding nanoparticles@Co‐ZIF‐67. To verify the structural advantages of hollow structural Co‐MOF‐74 and Ag nanoparticles@Co‐MOF‐74, photocatalytic CO₂ reduction is used as a model reaction. Conventionally synthesized Co‐MOF‐74 (MOF‐74‐C), hollow structural Co‐MOF‐74 synthesized by transformation method (MOF‐74‐T) and Ag nanoparticles@Co‐MOF‐74 (AgNPs@MOF‐74) are used as cocatalysts in this reaction. As a result, the cocatalytic activity of MOF‐74‐T and AgNPs@MOF‐74 is 1.8 times and 3.8 times that of MOF‐74‐C, respectively.     

Introduction of Red‐Green‐Blue Fluorescent Dyes into a Metal–Organic Framework for Tunable White Light Emission

The unique features of the metal–organic frameworks (MOFs), including ultrahigh porosities and surface areas, tunable pores, endow the MOFs with special utilizations as host matrices. In this work, various neutral and ionic guest dye molecules, such as fluorescent brighteners, coumarin derivatives, 4‐(dicyanomethylene)‐2‐methyl‐6‐(p‐dimethylaminostyryl)‐4H‐pyran (DCM), and 4‐(p‐dimethylaminostyryl)‐1‐methylpyridinium (DSM), are encapsulated in a neutral MOF, yielding novel blue‐, green‐, and red‐phosphors, respectively. Furthermore, this study introduces the red‐, green‐, and blue‐emitting dyes into a MOF together for the first time, producing white‐light materials with nearly ideal Commission International ed'Eclairage (CIE) coordinates, high color‐rendering index values (up to 92%) and quantum yields (up to 26%), and moderate correlated color temperature values. The white light is tunable by changing the content or type of the three dye guests, or the excitation wavelength. Significantly, the introduction of blue‐emitting guests in the methodology makes the available MOF host more extensive, and the final white‐light output more tunable and high‐quality. Such strategy can be widely adopted to design and prepare white‐light‐emitting materials.     

Encapsulation,Visualization and Expression of Genes with Biomimetically Mineralized Zeolitic Imidazolate Framework‐8 (ZIF‐8)

Recent work in biomolecule‐metal–organic framework (MOF) composites has proven to be an effective strategy for the protection of proteins. However, for other biomacromolecules such as nucleic acids, the encapsulation into nano MOFs and the related characterizations are in their infancy. Herein, encapsulation of a complete gene‐set in zeolitic imidazolate framework‐8 (ZIF‐8) MOFs and cellular expression of the gene delivered by the nano MOF composites are reported. Using a green fluorescent protein (GFP) plasmid (plGFP) as a proof‐of‐concept genetic macromolecule, successful transfection of mammalian cancer cells with plGFP for up to 4 days is shown. Cell transfection assays and soft X‐ray cryo‐tomography (cryo‐SXT) demonstrate the feasibility of DNA@MOF biocomposites as intracellular gene delivery vehicles. Expression occurs over relatively prolonged time points where the cargo nucleic acid is released gradually in order to maintain sustained expression.     

Nanoarchitectured Design of Porous Materials and Nanocomposites from Metal‐Organic Frameworks

The emergence of metal‐organic frameworks (MOFs) as a new class of crystalline porous materials is attracting considerable attention in many fields such as catalysis, energy storage and conversion, sensors, and environmental remediation due to their controllable composition, structure and pore size. MOFs are versatile precursors for the preparation of various forms of nanomaterials as well as new multifunctional nanocomposites/hybrids, which exhibit superior functional properties compared to the individual components assembling the composites. This review provides an overview of recent developments achieved in the fabrication of porous MOF‐derived nanostructures including carbons, metal oxides, metal chalcogenides (metal sulfides and selenides), metal carbides, metal phosphides and their composites. Finally, the challenges and future trends and prospects associated with the development of MOF‐derived nanomaterials are also examined.     

Self‐Sacrificial Template‐Directed Vapor‐Phase Growth of MOF Assemblies and Surface Vulcanization for Efficient Water Splitting

Direct use of metal–organic frameworks (MOFs) with robust pore structures, large surface areas, and high density of coordinatively unsaturated metal sites as electrochemical active materials is highly desirable (rather than using as templates and/or precursors for high‐temperature calcination), but this is practically hindered by the poor conductivity and low accessibility of active sites in the bulk form. Herein, a universal vapor‐phase method is reported to grow well‐aligned MOFs on conductive carbon cloth (CC) by using metal hydroxyl fluorides with diverse morphologies as self‐sacrificial templates. Specifically, by further partially on‐site generating active Co₃S₄ species from Co ions in the echinops‐like Co‐based MOF (EC‐MOF) through a controlled vulcanization approach, the resulting Co₃S₄/EC‐MOF hybrid exhibits much enhanced electrocatalytic performance toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with overpotentials of 84 and 226 mV required to reach a current density of 10 mA cm^?2, respectively. Density functional theory (DFT) calculations and experimental results reveal that the electron transfer between Co₃S₄ species and EC‐MOF can decrease the electron density of the Co d‐orbital, resulting in more electrocatalytically optimized adsorption properties for Co. This study will open up a new avenue for designing highly ordered MOF‐based surface active materials for various electrochemical energy applications.     

Porous Pt‐Ni Nanowires within In Situ Generated Metal‐Organic Frameworks for Highly Chemoselective Cinnamaldehyde Hydrogenation

Although chemoselective hydrogenation of unsaturated aldehydes is the major route to highly valuable industrially demanded unsaturated alcohols, it is still challenging, as the production of saturated aldehydes is more favorable over unsaturated alcohols from the view of thermodynamics. By combining the structural features of porous nanowires (NWs) and metal‐organic frameworks (MOFs), a unique class of porous Pt‐Ni NWs in situ encapsuled by MOFs (Pt‐Ni NWs@Ni/Fex‐MOFs) is designed to enhance the unsaturated alcohols selectivity in the cinnamaldehyde (CAL) hydrogenation. A detailed catalytic study shows that the porous Pt‐Ni NWs@Ni/Fe_x‐MOFs exhibit volcano‐type activity and selectivity in CAL hydrogenation as a function of Fe content. The optimized porous PtNi_2.20 NWs@Ni/Fe₄‐MOF is highly active and selective with 99.5% CAL conversion and 83.3% cinnamyl alcohol selectivity due to the confinement effect, appropriate thickness of MOF and its optimized electronic structure, and excellent durability with negligible activity and selectivity loss after five runs.     

miRNA‐Specific Unlocking of Drug‐Loaded Metal–Organic Framework Nanoparticles: Targeted Cytotoxicity toward Cancer Cells

UiO‐68 metal–organic framework nanoparticles (NMOFs) are loaded with a doxorubicin drug (fluorescent dye analogs) and locked by means of structurally engineered duplex nucleic acid structures, where one strand is covalently linked to the NMOFs and the second strand is hybridized with the anchor strand. Besides the complementarity of the second strand to the anchor sequence, it includes the complementary sequence to the microRNAs (miRNA)‐21 or miRNA‐221 that is specific miRNA biomarker for MCF‐7 breast cancer cells or OVCAR‐3 ovarian cancer cells. In the presence of the respective miRNA biomarkers, the miRNA‐induced displacement of the strand associated with the anchor strand proceeds, resulting in the release of DNA/miRNA duplexes. The released duplexes are, however, engineered to be digested in the presence of exonuclease III, Exo III, a process that recycles the miRNAs and provides the autonomous amplified unlocking of the NMOFs and the release of the doxorubicin load (or the fluorescent dye analogs) even at low concentrations of miRNA. Preliminary cell experiments reveal that the respective NMOFs are unlocked by the miRNA‐21 or miRNA‐221, resulting in selective cytotoxicity toward MCF‐7 breast cancer cells or OVCAR‐3 ovarian cancer cells.     

Ternary Alloys Encapsulated within Different MOFs via a Self‐Sacrificing Template Process: A Potential Platform for the Investigation of Size‐Selective Catalytic Performances

Functional nanoparticles encapsulated within metal–organic frameworks (MOFs) as an emerging class of composite materials attract increasing attention owing to their enhanced or even novel properties caused by the synergistic effect between the two functional materials. However, there is still no ideal composite structure as platform to systematically analyze and evaluate the relation between the enhanced catalytic performance of composites and the structure of MOF shells. In this work, taking RhCoNi ternary alloy nanoflowers, for example, first the RhCoNi@MOF composite catalysts sheathed with different structured MOFs via a facile self‐sacrificing template process are successfully fabricated. The structure type of MOF shells is easily adjustable by using different organic molecules as etchant and coordination reagent (e.g., 2,5‐dihydroxyterephthalic acid or 2‐methylimidazole), which can dissolve out the Co or Ni element in the alloy template in a targeted manner, thereby producing ZIF‐67(Co) or MOF‐74(Ni) shells accordingly. With the difference between the two MOF shells in the aperture sizes, the as‐prepared two RhCoNi@MOF composites preform distinct size selectivity during the alkene hydrogenation. This work would help us to get more comprehensive understanding of the intrinsic role of MOFs behind the enhanced catalytic performance of nanoparticle@MOF composites.