Two-dimensional Metal-organic Framework Research Articles

Two-dimensional metal-organic framework nanosheets coated solid-phase microextraction Arrow coupled with UPLC-Q-ToF-MS for the determination of three veterinary residues in milk and pork

This study presents a method utilizing solid-phase microextraction Arrow (SPME Arrow) combined with ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) for the selective detection of three veterinary drugs-thiabendazole, sulfamethazine, and clenbuterol-in milk and pork. Two-dimensional metal-organic framework nanosheets (2D-MOFs) were employed as coating materials for the SPME Arrow. Three types of 2D-MOFs (Ni, Mn, and Co based) were synthesized and characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and a physical adsorption analyzer. The 2D-MOF coatings were fabricated using the electrospinning technique, with polyacrylonitrile (PAN) serving as the binder. Comparative analysis of the three 2D-MOF coatings revealed that 2D-Ni-MOF was the optimal coating material for the SPME Arrow. Optimization of the coating preparation conditions and SPME procedures included determining the optimal mass ratio of 2D-Ni-MOF to PAN, electrospinning time, and extraction and desorption parameters. Equilibrium extraction was achieved within 60 minutes, and desorption was completed within 30 minutes. Subsequently, the 2D-Ni-MOF-SPME Arrow-UPLC-Q-TOF-MS method was established and validated under optimal conditions, demonstrating high precision with inter-day precision ranging from 3.8% to 9.5% and intra-day precision ranging from 5.1% to 11.5%. The reusability study indicated that the extraction performance of the new SPME Arrow remained consistent after 90 adsorption-desorption cycles. The method exhibited linearity in milk and pork over the ranges of 0.002–5 μg L–1 and 0.01–5 μg L–1, respectively. The detection limits in milk and pork were 0.001–0.004 μg L–1 and 0.003–0.007 μg L–1, respectively. This method demonstrated excellent applicability for determining residues of the three veterinary drugs in milk and pork.

Bio-heterointerface charging through ultrasound-boosted extracellular and intracellular electron transfer for rapid bacterial killing

The deep-seated drug-resistant bacterial infection is one of the most noticeable public-health threat owing to poor drug therapeutic effect, high recurrence, and devastating complication. Herein, we propose a bactericidal strategy of bio-heterointerface charging through ultrasound-boosted bacterial extracellular and intracellular electron transfer for eradicating implant-related drug-resistant bacterial infection, where a TiO2-modified porphyrin-based two-dimensional metal-organic framework (2DMOF-TiO2) is selected as a sonosensitizer. The ultrasound-boosted extracellular and intracellular electron transfer between methicillin-resistant Staphylococcus aureus and 2DMOF-TiO2 induces rapid reactive oxygen species (ROS) burst surrounding bacterial outer and inner, contributing to intracellular oxidation, membrane potential decrease (∼5 mV), membrane disruption, and pyrimidine metabolism disorder, thus causing bacterial death. The in vivo results of 2DMOF-TiO2 implant exhibit rapid sonocatalytic anti-infection and enhanced osseointegration at bone-implant interface. This platform may inspire the universal thinking about ultrasound-boosted extracellular and intracellular electron-transfer-induced ROS and provide a superior therapeutic candidate for various deep-seated infectious diseases.

Solvent-mediated synthesis of 2D In-TCPP MOF nanosheets for enhanced photodynamic antibacterial therapy

Two-dimensional (2D) metal-organic frameworks (MOFs) have emerged as promising photosensitizers in photodynamic therapy in recent years. In comparison to bulk MOFs, constructing 2D MOFs can increase the presence of active sites through increasing the surface area ratio. Herein, we report a simple solvent-mediated synthesis method for preparation of 2D porphyrin-based MOF (In-TCPP) nanosheets without the addition of any surfactants as an efficient photosensitizer for enhancing photodynamic antibacterial therapy. The accurate regulation of the morphology and size of 2D In-TCPP nanosheets can be achieved by varying the ratio of water to N,N-dimethylformamide solvent with the appropriate assistance of pyridine. The optimal synthesized 2D In-TCPP nanosheets exhibit a diameter of 70-120 nm and a thickness of 21.5-27.4 nm. Promisingly, 2D In-TCPP nanosheets produce a higher amount of 1O2 when exposed to 660 nm laser compared to the In-TCPP bulk, indicating that the smaller nanosheets possess more active sites for reactive oxygen species generation and can greatly improve the antibacterial photodynamic therapeutic effect. Both the in vitro and in vivo results prove that the In-TCPP nanosheets can be used as a photosensitizer for efficient photodynamic antibacterial therapy to kill S. aureus and promote wound healing.

Two-Dimensional Silver-Isocyanide Frameworks.

Metal-organic frameworks (MOFs) have been widely studied due to their versatile applications and easily tunable structures. However, heteroatom-metal coordination dominates the MOFs community, and the rational synthesis of carbon-metal coordination-based MOFs remains a significant challenge. Herein, two-dimensional (2D) MOFs based on silver-carbon linkages are synthesized through the coordination between silver(I) salt and isocyanide-based monomers at ambient condition. The as-synthesized 2D MOFs possess well-defined crystalline structures and a staggered AB stacking mode. Most interestingly, these 2D MOFs, without π-π stacking between layers, exhibit narrow bandgaps down to 1.42 eV. As electrochemical catalysts for converting CO2 to CO, such 2D MOFs demonstrate Faradaic efficiency over 92%. Surprisingly, the CO2 reduction catalyzed by these MOFs indicates favorable adsorption of CO2 and *COOH on the active carbon sites of the isocyanide groups rather than on silver sites. This is attributed to the critical σ donor role of isocyanides and the corresponding ligand-to-metal charge-transfer effect. This work not only paves the way toward a new family of MOFs based on metal-isocyanide coordination but also offers a rare platform for understanding the electrocatalysis processes on strongly polarized carbon species.

Mixed matrix membranes (MMMs) fabricated via ultrathin Cu-MOF nanosheets for CO2/N2 separation: Low loading but high performance

Emerging two-dimensional metal-organic frameworks (MOFs) were widely utilized in the fabrication of mixed matrix membranes (MMMs) for CO2/N2 separation, owing to their high specific surface area, high aspect ratio, layered structure, and nanoscale thickness. In the current work, a novel Cu-MOF nanosheet with an approximate thickness of ∼20 nm has been synthesized for the first time and used as nanofillers to fabricate MMMs with Pebax 2533. In the MMMs, these Cu-MOF nanosheets could self-assemble into a unique stacked configuration within the Pebax matrix, facilitating rapid CO2 transport while extending the transport path for N2, thereby enhancing both CO2 permeability and CO2/N2 selectivity of the obtained Pebax-Cu-MOF MMMs. Furthermore, the high aspect ratio of the Cu-MOF nanosheets promotes good interaction with Pebax, thereby improving interfacial compatibility. Under conditions of 2 bar and 35 °C, the CO2 permeability and CO2/N2 selectivity of the Pebax-Cu-MOF 0.2 wt.% MMM was 619.1 Barrer and 23.89, respectively, representing increases of 231.6 % and 112.4 % compared to pure Pebax. The MMMs also demonstrated excellent long-term stability. These novel Cu-MOF nanosheets exhibit significant potential for applications across a wide range of fields.

High-Performance H2S Sensors to Detect SF6 Leakage.

Detecting H2S in oxygen-deficient conditions is vital for identifying leaks in SF6-insulated electrical equipment. Current infrared-based detection methods are expensive and sensitive to environmental conditions, highlighting the necessity for cost-effective and stable gas sensors. Existing gas sensors based on semiconducting metal oxides (SMOXs) are limited by redox reactions with oxygen and require high operating temperatures. Here, we introduce a room-temperature (RT) H2S sensor for oxygen-deficient environments using the intrinsic conducting two-dimensional (2D) metal-organic framework (MOF), Co1.8Ni1.2(hexaiminotriphenylene)2 [Co1.8Ni1.2(HITP)2], overcoming the limitations of SMOX gas sensors. Remarkably, Co1.8Ni1.2(HITP)2 sensors exhibit exceptional selectivity for H2S with negligible cross-responses and a sensitivity drift of less than 4.13% in an SF6 atmosphere over 60 days. The Co1.8Ni1.2(HITP)2 gas sensor shows significant promise for real-time and stable monitoring of H2S gas in oxygen-deficient environments.

F-π* Back Bonding Orbital Induced by Lutetium-Based Conducting MOF Promotes Highly Selective CO 2 to CH 4 at Low Potential.

The research on electrocatalytic carbon dioxide reduction (ECR) catalysts using renewable energy is particularly crucial in energy conversion studies, especially for viable hydrocarbon production. This study employs density functional theory calculations to screen a series of non-radioactive lanthanide two-dimensional metal-organic frameworks (MOFs) for product selectivity in ECR. Based on theoretical screening, our focus is on a lutetium (Lu)-based conducting MOF (Lu-HHTP), which exhibits a Faradaicefficiency of approximately 77% for methane (CH4) production and maintains a stable current density of -280 mA/cm2at -1.1 V vs. RHE. In situ electrochemical experiments and material characterization demonstrate that the Lu sites possess high coordination stability and structural recoverability during catalytic CO2reduction, attributed to the overlap between Lu's f-orbitalsand the π*-orbitals of the ligand O, and the formation of back bonding orbitals between the f-orbitals of Lu and the π* orbitals of CO contribute increasing CH₄selectivity and lowering the potential. This study leverages rare-earth MOF-type materials, offering a novel approach to addressing low conductivity and stabilizing rare-earth materials, thereby establishing a theoretical framework for the conversion of linearly adsorbed *CO into hydrocarbons.

Enhancing Magnetic Ordering in Two-Dimensional Metal-Organic Frameworks via Frontier Molecular Orbital Engineering.

Two-dimensional (2D) metal-organic frameworks (MOFs) have promise for use in lightweight permanent magnets in contrast to inorganic solid- or molecule-based magnets, but the realization of 2D MOF magnets with a high ordering temperature is limited by the typically weak spin exchange interactions. Here, we have proposed a frontier molecular orbital engineering strategy for modulating magnetism in 2D MOFs. It shows that the magnetic ground state can be mediated by two intra-atomic spin exchange pathways in organic ligands, akin to the Bloch and Heisenberg models, depending on the shape of the frontier orbitals of the organic ligands. By engineering the shape of the lowest unoccupied molecular orbital (LUMO) via chemical hydrogenation, we achieved a nearly 11-fold increase in the ordering temperature. In particular, a quantitative analysis shows that the ordering temperature increases linearly with the orbital delocalization index of the ligands' LUMO. This work suggests a general frontier orbital engineering approach for modulating the spin exchange interaction in 2D MOF magnets.

2D mesh-knots metal organic frameworks functionalized with phytic acid for improving flame retardancy

Metal ions and organic compounds were adopted to form a two-dimensional mesh-knots metal organic frameworks (TMMOFs), which could functionalize with Phytic Acid (PA) for fireproof. The results of the functional group test show that two-dimensional mesh-knots metal organic frameworks (TM), TM with -NH2 (TMN) and TMN with PA (TMNP) have been successfully prepared by coordination bond. The samples appeared irregular ellipsoid with size of particles below 100 nm. The values of limiting oxygen index (LOI) test depicted the flame resistance have been enhanced from 22.7 % to 30 % due to the addition of -NH2 and PA. The peak heat release rate (pHRR) and total heat release (THR) value of TM-PA@wood declined noticeably by 55.9 % and 68.6 % compared to pure wood. CO2 emissions intensity of TMNP@wood declined from about 0.40 to 0.12 compared with samples without PA. The CO2 and CO maximum production of TMNP@wood were significantly lower 246% and 64% than TMN@wood, respectively. PA and ZrO2 after combustion could catalyze wood to form carbon residue as condense phase, delay and minimize the peak of CO2 and CO to reduce toxicity. This work provides an effective strategy for synthesis and application of two-dimensional materials in flame retardant field.

Two-dimensional metal-organic framework nanoleaf embedded with nitrogen-doped carbon dots for monitoring of picric acid

A novel preparation of 2D metal–organic framework (Zn-MOF, ZIF-8) nanoleaf (ZIF-L) embedded with nitrogen-doped carbon dots (NCDs) was applied successfully. The NCDs are synthesized through hydrothermal treatment of citric acid and ethylenediamine exhibiting excitation wavelength independence (λex-independence) of 6 nm and higher quantum yield reaches 84 %. The ZIF-L embedded with NCDs generates a 2D continuous framework of NCDs@ ZIF-L nanocomposite. The nanocomposite was fully characterized by FTIR, XRD, TEM, and N2 adsorption-desorption mechanism. The XRD data reveals no significant change in the crystallinity of ZIF-L upon the encapsulation of NCDs, but it enhances the fluorescence emission. The synergetic cooperation between ZIF-L and NCDs might free active sites that lead to higher adsorption capacity and thus enhance their application in chemical sensing. The NCDs@ZIF-L nanocomposite synergistically combines active-rich-electron nanospaces with a high surface area, both of which are particularly beneficial for the selective detection of hazardous picric acid (PA) because of reinforced hydrogen bonding interactions with the hydroxyl groups of PA aromatic rings. The NCDs@ZIF-L framework is utilized to monitor PA as a nitro explosive compound in aqueous media exhibiting a high sensing activity and selectivity to detect PA in diluted solutions with a low detection limit (LOD) reaching 0.139 µM. The nanocomposite was also utilized in real water samples spiked with different concentrations of PA in tap water, with R % reaching 91.3–102 % and RSD % less than 5 %, showing their applicability to detect PA under circumstances.

Polydopamine-assisted minute fabrication of vertically aligned ZIF-L membranes for CO2/N2 separations

Metal-organic framework (MOF) membranes demonstrate significant potential for industrial gas separations, yet fabricating vertically aligned two-dimensional (2D) MOF membranes on polymer substrates remains a considerable challenge due to the weak adhesion and difficulty in achieving precise alignment. This study presents a one-step method for the rapid synthesis of vertically aligned ZIF-L membranes, using a polydopamine (PDA)-assisted approach. This method enables the rapid formation of homogenous, thin but defect-free membranes on polymer substrates within 5 min, drastically reducing the preparation time by over 200 times. The vertically aligned ZIF-L membranes, characterized by the interlayer galleries facing the gas mixtures, exhibit an excellent CO2 permeance exceeding 1200 GPU and a CO2/N2 selectivity of 14.5. The versatility of this approach allows for its application on various flat-sheet or even hollow fiber supports. Our findings highlight the potential of PDA-assisted synthesis for efficient, scalable preparation of high-performance MOF membranes for industrial gas separations.

Construction of Pillared-Layer Metal-Organic Frameworks as an All-Visible-Light Switchable Photocatalyst for Aqueous Cr(VI) Reduction.

Recently, two-dimensional metal-organic frameworks that are photoactive have shown great potential for efficiently converting solar energy into chemical energy. In this work, we successfully synthesized and designed two M2-MOFs ([Cu(L1)((CH3)2NH)]n (Cu-MOF) and [Zn(L1)(CH3)2NH)]n (Zn-MOF), H2L1 = 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid). Structural analysis suggests that the five-coordinated M(II) ion is surrounded by four oxygen ions from two ligands and one nitrogen atom from one dimethylamine molecule. The ligand spacer acts as a bridge between two SBUs and forms a 2D layer with rhomboid windows. These moieties are arranged in a staggered ABAB pattern, which likely aids in exfoliation. The UV-vis diffuse reflectance spectra (DRS) test shows that when the metal center in the MOF framework is replaced with Cu(II) ions, the light absorption range covers 200-1100 nm, which is much larger than the light absorption range of Zn-MOF. Moreover, the photoelectric current, electrochemical impedance spectra (EIS), and Mott-Schottky tests all indicate that Cu-MOF has better photoelectric properties. When applied to the photocatalytic reduction of Cr(VI), Cu-MOF and Zn-MOF can completely reduce Cr(VI) within 100 min under 450 nm LED light irradiation. Under sunlight irradiation, Cu-MOF can completely reduce Cr(VI) within 40 min, achieving the removal of Cr(VI) ions, which is much faster than the rate of Cr(VI) removal by Zn-MOF.

The “d-p orbital hybridization”-guided design of novel two-dimensional MOFs with high anchoring and catalytic capacities in Lithium − Sulfur batteries

The energy system of lithium-sulfur batteries is quite promising, however, lithium-sulfur batteries still suffer from considerable problems, such as the abominable shuttle effect of polysulfides (LiPSs), the low conductivity of the solid-phase products, the slow redox kinetics during charging and discharging, and the volume expansion. Herein, the hybridization pattern between the d-orbitals of various transition metal atoms and the p-orbitals of sulfides is revealed grounded in the theory of density function, which explains the high adsorption strength of two-dimensional metal–organic frameworks (MOFs) with LiPSs and accelerates the screening of high-performance anchoring and catalytic materials. The results elucidate that the coordinated transition metal–organic frameworks (Mo-NH MOF) monolayers increase the capacity of LiPSs to anchor by forming more π-bonds from the hybridization of the S p orbitals and Mo d orbitals. Notably, Mo-NH MOF exhibits bifunctional catalytic activity for sulfur reduction as well as Li2S decomposition reactions during charging and discharging, which improves the conversion efficiency of redox reactions. As a result, new MOF materials featuring unique active centers and the potential mechanism by which the active centers modulate the performance of the substrate materials are revealed, and this finding may accelerate the development of high-performance Li-S batteries.

Interfacial modulation strategy using poly(3,4-ethylenedioxythiophene)–poly(4-styrenesulfonate) (PEDOT:PSS) and ultrathin two-dimensional metal–organic framework nanosheets for wearable supercapacitors: Solution engineering

Two-dimensional metal–organic frameworks (2D MOFs) hold great promise as electrochemically active materials. However, their application in MOF nanocomposite electrodes in solution engineering is limited by structural self-stacking and imperfect conductive pathways. In this study, we used meso-tetra(4-carboxyphenyl) porphine (TCPP) with off-domain π-bonds to reconstitute Zn-TCPP (ZMOF) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) through an interfacial modulation strategy involving electrostatic coupling and hydrogen bonding, creating a conductive composite with a nanosheet structure. The negatively charged PSS and ZMOF formed a three-dimensional interconnected conductive network with excellent interfaces. The positively charged PEDOT, fine tuned with the lamellar structure, established strong π-π stacking interactions between the porphyrin and thiophene rings. ZMOF also induced changes in the PEDOT chain structure, weakening PSS entanglement and enhancing charge-transport properties. The specific capacitance of the prepared supercapacitor was as high as 967.8 F g−1. Flexible supercapacitors produced on a large scale using dispensing printing technology exhibited an energy density of 1.85 μWh cm−2 and a power density of 7.08 μW cm−2. This interfacial modulation strategy also exhibited excellent wearable properties, with 96 % capacitance retention at a 180° bending angle and stable cycling performance. This study presented a significant advancement in the functionalization of 2D materials, highlighting their potential for device-grade capacitive architectures.

O-arylation reaction over lanthanide metal–organic framework: Synthesis, structure and catalytic reaction

Two novel lanthanide based two-dimensional metal-organic framework (MOF) compounds [Tb(NDC)(NO3)(DMA)2]n (MOF-1) and [Ho(NDC)(NO3)(DMA)2]n (MOF-2) [H2NDC=2,6-naphthalenedicarboxylic acid and DMA=N,N-dimethylacetamide] have been synthesized following solvothermal route and structurally characterized. Structural analysis reveals that both the compounds are crystallized in the orthorhombic crystal system with space group Pbca. MOFs feature a “paddle-wheel” (PW) type core building units which are constructed via carboxylato oxygen coordination with lanthanide atoms. 2D lanthanide based MOFs consist of paddle-wheel building block are rare in the literature. MOF-1 and MOF-2 possess an octa-coordinated metal center. Apart from carboxylato groups, oxygen atoms of DMA and NO3− ions are also coordinated to metal centers. Paddle-wheel cores are interconnected to each other to give rise to layered network structure in both the cases. 2D layers are propagated parallel to bc plane and layers are stacked one upon another along the crystallographic a axis. Notably, both MOF-1 and MOF-2 are capable to catalyze O-arylation reaction efficiently under heterogeneous medium. However, amongst them, catalytic efficacy of MOF-1 towards O-arylation reaction is found to be better than that of MOF-2.

(Invited) Two-Dimensional Metal–Organic Framework Acts As a Hydrogen Evolution Cocatalyst for Overall Photocatalytic Water Splitting

Water-splitting semiconductor photocatalysts require hydrogen evolution reaction (HER) cocatalysts, the majority of which are robust metals and metal oxides. Metal complexes feature designability and reaction selectivity. This feature should be appreciated in the application as HER cocatalysts by suppressing unfavorable back reactions; however, low stability hampers their application. In this research, we demonstrate that a fully π-conjugated and conductive two-dimensional metal–organic framework (2D MOF), which possesses both virtues of metals/metal oxides and metal complexes, serves as an ideal HER cocatalyst candidate. NiBHT, a kind of 2D MOF, is deposited on the photocatalyst SrTiO3:Al with CoO x as an oxygen evolution cocatalyst to show long-term overall one-step water splitting with an apparent quantum efficiency (AQE) of 6.5% at 350 nm. In comparison to Pt as a representative HER cocatalyst, NiBHT turns out to be a suppressor of back reactions related to oxygen reduction reactions, which is proven both experimentally and theoretically.

Aptasensor based on gold nanostructure-decorated 2D Cu metal-organic framework nanosheets for highly sensitive and specific electrochemical lipopolysaccharide detection.

Detecting lipopolysaccharide (LPS) using electrochemical methods is significant because of theirexceptional sensitivity, simplicity, and user-friendliness. Two-dimensional metal-organic framework (2D-MOF) that merges the benefits of MOF and 2D nanostructure has exhibited remarkable performance in constructing electrochemical sensors, notably surpassing traditional 3D-MOFs. In this study, Cu[tetrakis(4-carboxylphenyl)porphyrin] (Cu-TCPP) and Cu(tetrahydroxyquinone) (Cu-THQ) 2D nanosheets were synthesized and applied on a glassy carbon electrode (GCE). The 2D-MOF nanosheets, which serve as supporting layers, exhibit improved electron transfer and electronic conductivity characteristics. Subsequently, the modified electrode was subjected to electrodeposition with Au nanostructures, resulting in the formation of Au/Cu-TCPP/GCE and Au/Cu-THQ/GCE. Notably, the Au/Cu-THQ/GCE demonstrated superior electrochemical activity because of the 2D morphology, redox ligand, dense Cu sites, and improved deposition of flower-like Au nanostructure based on Cu-THQ. The electron transfer specific surface area was increased by the improved deposition of Au nanostructures, which facilitates enriched binding of LPS aptamer and significantly improved thedetection performance of Apt/Au/Cu-THQ/GCE electrochemical aptasensor. The limit of detection for LPS reached 0.15fg/mL with a linear range of 1fg/mL - 100pg/mL. Theproposed aptasensor demonstrated the ability to detect LPS in serum samples with satisfactory accuracy, indicating significant potential for clinical diagnosis.

Expression of Concern: In-Silico Tuning of the Nano-Bio Interface by Molecular Dynamics Method: Amyloid beta Targeting with Two-Dimensional Metal-organic Frameworks

Expression of Concern: In-Silico Tuning of the Nano-Bio Interface by Molecular Dynamics Method: Amyloid beta Targeting with Two-Dimensional Metal-organic Frameworks

Decorating Cage-Shaped Cavities with Carboxyl Groups on Two-Dimensional MOF Nanosheet for Trace Uranium(VI) Trapping.

The efficient and complete extraction of uranium from aqueous solutions is crucial for safeguarding human health from potential radiotoxicity and chemotoxicity. Herein, an ultrathin 2D metal-organic framework (MOF) nanosheet with cavity structures was elaborately constructed, based on a calix[4]arene ligand. The large molecular skeleton and cup-shaped feature of the calix[4]arene enabled the as-prepared MOFs with large layer separations, which can be readily delaminated into ultrathin single-layer (∼1.25 nm) nanosheets. The incorporation of permanent cavity structures to the MOF nanosheets can fully utilize their structural features of readily accessible adsorption groups and exposed surface area in uranium removal, reaching ultrafast adsorption kinetics; the functionalized cavity structure endowed MOF nanosheets with the ability to preconcentrate and extract uranium from aqueous solutions with ultrahigh efficiencies, even at extremely low concentrations. As a result, relatively high removal ratios (>95%) can be achieved for uranium within 5 min, even in the ultralow concentration range of 75-250 ppb, and the residual uranium was reduced to below 4.9 ppb. The MOF nanosheets also exhibited extremely high anti-interference ability, which could efficiently remove the low-level uranium (∼150 ppb) from various real samples. The characterizations and density functional theory calculations demonstrated that the synergistic effects of multiple interactions between the carboxylate groups and cage-like cavities with uranyl ions can be responsible for the efficient and selective uranium extraction.

Fabricating Large-Area Thin Films of 2D Conductive Metal-Organic Frameworks.

ConspectusRecent years have witnessed significant interest in two-dimensional metal-organic frameworks (MOFs) due to their unique properties and promising applications across various fields. These materials offer distinct advantages, including high porosity and excellent charge transport properties. Their tunability allows precise control over various factors, including the electronic structure adjustments and local reactivity modulation, facilitating a wide range of properties and applications, such as material sensing and spin dynamics control. Moreover, the precise crystal structure of 2D MOFs supports rational design and mechanism studies, providing insights into their potential applications and enhancing their utility in various scientific and technological endeavors.To fully unveil the latent capabilities of 2D MOFs and advance their applications across diverse fields, thin film synthesis is crucial. Thin films provide a platform for investigating the intrinsic electrical properties of 2D MOFs with anisotropic structures, enabling the exploration of their unique characteristics comprehensively. Additionally, thin films offer the advantage of minimizing interference at contacts and junctions, thereby enhancing the performance of 2D MOFs for various applications. Furthermore, the properties of thin films can vary with thickness, presenting an opportunity to tailor their characteristics based on specific requirements.In this Account, we present an overview of our research focusing on the synthesis of 2D conductive MOF thin films encompassing two primary methods: chemical vapor deposition and solution processing. The chemical vapor deposition method allows for one-step, all-vapor-phase processes resulting in MOFs with edge-on orientation, controllable film thicknesses ranging from 55 to 662.7 nm, and smooth, homogeneous surfaces. On the other hand, solution-processing introduces a novel MOF, Cu3(HHTATP)2, by reducing interlayer interactions through the addition of pendent Brønsted bases on a ligand, enabling spin coating for thin film synthesis. This method yields a concentrated 2D MOF solution, enabling spin coating for thin film synthesis, where reversible electrical conductivity changes occur through doping with an acid and dedoping with a base. Additionally, we discuss various other synthesis methods, such as interfacial synthesis, layer-by-layer assembly, and microfluidic-assisted synthesis, offering versatile approaches for fabricating large-area thin films with tailored properties. Finally, we address ongoing challenges and potential strategies for further advancement in 2D conductive MOF thin film synthesis. We hope that this Account provides insights for selecting synthesis methods tailored to specific purposes, contributes to the development of varied synthesis techniques, and facilitates the exploration of diverse applications, unlocking the full potential of 2D conductive MOFs for next-generation technologies.