Copper-based Metal-organic Framework Research Articles

Preparation of MOF-199/polyacrylonitrile nanofiber membrane and its application in the preparation of flexible VOC gas sensors

A copper-based metal–organic framework (MOF-199) demonstrates excellent performance and considerable potential in the gas detection of volatile organic compounds (VOCs). However, the powder of MOF-199 seriously limits its application in the fabrication of flexible devices. Herein, we introduce a simple method of blending electrospinning, combining MOF-199 with polyacrylonitrile (PAN) nanofiber to form a MOF-199/PAN nanofiber membrane with the flexibility of PAN nanofiber and the functionality of MOF-199. The capacitive sensor comprising MOF-199/PAN nanofiber membrane and carbon nanotubes exhibits good flexibility, high porosity, and sufficient adsorption active sites. The sensor has the highest response to methanol among seven target VOCs. It exhibits outstanding sensitivity, long-term stability, good linear response, and repeatability toward methanol (250–1250 ppm). Owing to the flexibility of the MOF-199/PAN nanofiber membrane, the sensor maintains a stable sensing response after repeated bending at 180˚–0˚ 50 times and exhibits a certain degree of response in the 180˚ bending state. The results show that the sensor has flexibility potential. These provides some ideas and reference for the development of VOCs sensors.

Fabrication of 3D Oriented MOF Micropatterns with Anisotropic Fluorescent Properties.

Micropatterning crystalline materials with oriented pores is necessary for the fabrication of devices with anisotropic properties. Crystalline and porous metal-organic frameworks (MOFs) are ideal materials as their chemical and structural mutability enables precise tuning of functional properties for applications ranging from microelectronics to photonics. Herein, a patternable oriented MOF film is designed: by using a photomask under X-ray exposure, the MOF film decomposes in the irradiated areas, remaining intact in the unexposed regions. The MOF film acts simultaneously as a resist and as functional porous material. While the heteroepitaxial growth from aligned Cu(OH)2 nanobelts is used to deposit oriented MOF films, the sensitivity to radiation is achieved by integrating a brominated dicarboxylate ligand (Br2 BDC) into a copper-based MOF Cu2 L2 DABCO (DABCO = 1,4-diazabicyclo[2.2.2]octane; L = BDC/Br2 BDC). The lithographed samples act as diffraction gratings upon irradiation with a laser, thus confirming the quality of the extended MOF micropattern. Furthermore, the oriented MOF patterns are functionalized with fluorescent dyes. As a result, by rotating the polarization angle of the laser excitation, the alignment of the dye in the MOF is demonstrated. By controlling the functional response to light, this MOF patterning protocol can be used for the microfabrication of optical components for photonic devices.

Efficient phenolic compounds adsorption by immobilization of copper-based metal-organic framework anchored polyacrylonitrile/chitosan beads

The application of newly formulated beads from copper-benzenetricarboxylate (Cu-BTC), polyacrylonitrile (PAN), and chitosan (C), Cu-BTC@C-PAN, C-PAN, and PAN, for the removal of phenolic chemicals from water, is described in the current paper. Phenolic compounds (4-chlorophenol (4-CP) and 4-nitrophenol (4-NP)) were adsorbed using beads and the adsorption optimization looked at the effects of several experimental factors. The Langmuir and Freundlich models were used to explain the adsorption isotherms in the system. A pseudo-first and second-order equation is performed for describing the kinetics of adsorption. The obtained data fit (R2 = 0.999) supports the suitability of the Langmuir model and pseudo-second-order kinetic equation for the adsorption mechanism. Cu-BTC@C-PAN, C-PAN, and PAN beads' morphology and structure were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transforms infrared spectroscopy (FT-IR). According to the findings, Cu-BTC@C-PAN has very high adsorption capacities of 277.02, and 324.74 mg g−1, for 4-CP and 4-NP, respectively. The Cu-BTC@C-PAN beads showed 2.55 times higher adsorption capacity than PAN in the case of 4-NP, but in the case of 4-CP, it was higher by 2.64 times.

Development of carbon nanotube-metal organic framework (MOF) hybrid antiviral microfiltration membrane

We present the development of novel antiviral membranes by immobilizing metal organic framework (MOF) and carbon nanotubes (CNTs) on polymeric microfiltration membranes. The CNTs and the copper-based MOF (HKUST-1) were tested individually and in a hybrid form (MOF-CNT) against MS2 bacteriophage which was used as a surrogate virus. The membranes were synthesized at three different loading (5, 8 and 12% by weight) on a PVDF filtration membrane. The membranes were characterized using scanning electron microscopy, energy dispersive x-ray spectroscopy, thermogravimetric analysis, water contact angle, gas permeation tests and x-ray diffraction. Amongst the CNT immobilized (CNIM), MOF immobilized (MIM) and MOF-CNT (MCNIM) immobilized membranes, the permeate flux was highest for the CNIM (170% higher than MIM at 5% loading) followed by MCNIM (149% higher than MIM at 5% loading). This was because the small MOF particles blocked the membrane pores. No rejection of bacteriophages was observed with the plain PVDF membrane, but with the immobilization of MOF and CNTs, the antiviral activities increased with nano particles loading. The MCNIM with 12% loading exhibited a 99.6% phage deactivation. Kinetics of phage deactivation was studied for MOF, CNTs and MOF-CNT. The median lethal dose to kill 50% of the virus population (LD50) for MOF-CNT was as much as 70% lower than the CNTs and 30% lower than the pure MOF. Similarly, the time taken to deactivate 80% of the viral population (T80) for MOF-CNT was 50% less than the pure CNTs and 24% less than the pure MOF. Overall, the MOF-CNT immobilized membranes appear to be best option for antiviral activity.

MoC@Cu@C composites with structural advantages exhibit excellent electrochemical performance and stability in LIBs

Herein, we synthesized a porous carbon matrix composite (MoC@Cu@C) by pyrolyzing a compound consisting of a copper-based metal organic framework materials and a molybdenum-based polyoxometalate under nitrogen atmosphere. This is a mesoporous molybdenum carbide octahedron consisting of extremely small nanocrystals. Owing to the porous nature of the composite material and its surface-rich carbon matrix, it is believed to provide more active Li+ storage sites, which can enhance electrical conductivity and effectively inhibit volume expansion during cycling. Furthermore, the in-situ synthesis of copper in the sample can bring additional conductivity enhancement and good initial lithium deposition kinetics, doping of heteroatom N in organic ligands brings additional capacity. Benefit from this, the MoC@Cu@C anode shows good rate and cycling performance. When the battery is cycled 100 times at a current density of 100 mA g−1, it can achieve 100 % capacity retention with a high reversible capacity of 820 mAh g−1. Even when cycled at 2000 mA g−1, the capacity stabilizes at 526 mAh g−1, of which 98 % is retained after 1000 cycles. These features make the MoC@Cu@C composites a promising new generation of anode materials for LIBs.

Ambient temperature NO2 removal by reversible NO2 adsorption on copper-based metal-organic frameworks (MOFs)-derived nanoporous adsorbents

Nitrogen dioxide (NO2) is a potent atmospheric pollutant generated from fossil fuel combustion at power plants, industrial plants, and vehicles, which raises serious health concerns (e.g., respiratory diseases) and contributes to severe environmental pollution issues (e.g., acid rain and ground-level ozone). Adsorption is an efficient approach for ambient temperature NO2 removal, whose efficiency highly depends on the design of the adsorbents. The widely reported activated carbon adsorbents suffer from low and typically irreversible NO2 capacity apart from co-generation of considerable amounts of polluting NO (up to 50% of adsorbed NO2), which is released back into the atmosphere. Herein we report copper-based metal–organic framework (MOF)-derived carbon materials (i.e., Cu@C(CuBTC) and Cu@C(CuBDC)) featuring high NO2 capacity coupled with minimal release of NO and outstanding reusability for NO2 removal under ambient temperature. Both Cu@C(CuBTC) and Cu@C(CuBDC) showed an impressive improvement (up to 13.5 times) in NO2 capacity over their pristine MOFs counterparts, with Cu@C(CuBTC) showing the highest NO2 capacity (4.97 mmol/g) and minimal (<20 % of adsorbed NO2) release of NO in this study. Such a massive improvement in the NO2 capacity of carbonized composites is attributed to highly active and homogenously dispersed Cu nanoclusters, which serve as adsorption sites and play the dominant role in NO2 removal. Further, for the first time, Cu@C(CuBTC) exhibited outstanding reusability for NO2 removal under humid conditions, reflected by stable NO2 capacity in the cyclic adsorption tests (5 cycles), suggesting a great potential for real-world applications. This study provides a general and facile strategy for designing highly dispersed, water-resistant, and stable copper nanoclusters on carbon support for efficient adsorptive removal of various toxic gases under ambient temperature.

Gelatin-Coated Copper-Based Metal–Organic Framework for Controlled Insulin Delivery: Possibility toward Oral Delivery System

The development of nontoxic, hemocompatible materials for controlled insulin delivery is a great challenging task for researchers. Herein, we demonstrate the design of a novel linker 5,5′-((pyridine-2,6-diylbis(methylene)) bis(oxy))diisophthalic acid (H4L) and its utilization to synthesize a new Cu-MOF (IITI-3). IITI-3 crystallizes in a tetragonal crystal system with space group I4/mmm and shows a high Brunauer–Emmett–Teller (BET) surface area of 1026.5 m2/g with pore diameter (Barrett–Joyner–Halenda pore size distribution) of 3.413 nm. The IITI-3 is found to be stable in the biological fluid pH ranges from 3 to 10. Moreover, IITI-3 were explored for insulin delivery by coating the IITI-3 with gelatin (gel@insIITI-3); the overall insulin was controlled from the framework. The obtained result paves a new avenue for the oral delivery of insulin using the IITI-3 metal-organic framework.

Tribological properties of metal-organic framework nanosheets functionalized by oleic acid

<p indent="0mm">Terephthalic acid and copper acetate were used as raw materials, and copper-based metal-organic framework (Cu-MOF) nanosheets were synthesized by ultrasonic-assisted self-assembly. Afterward, oleic acid (OA) molecules were successfully modified on the surface of Cu-MOF by ultrasonic treatment to acquire Cu-MOF@OA nanosheets. The morphology of Cu-MOF@OA maintained its sheet structure; however, the size of the nanosheets was reduced, and the agglomeration problem was considerably alleviated compared with Cu-MOF nanosheets. The Cu-MOF@OA nanosheets exhibited good dispersion stability in <sc>500 N</sc> base oil. The tribological tests indicated that Cu-MOF@OA showed the best tribological properties at the addition concentration of 1.0 wt.%. Moreover, the friction coefficient and wear volume were reduced to 3/5 and 1/6 of the base oil, respectively. Finally, scanning electron microscopy and X-ray photoelectron spectroscopy were applied to characterize the morphology and characteristic elements of wear scar lubricated by Cu-MOF@OA nanosheets and explore the lubrication mechanism. The results indicated that complex tribochemical reactions occur among Cu-MOF@OA, base oil, and iron substrate under the action of load and shear stress during the friction experiment, forming a tribofilm composed of nitrogenous substances, carbonaceous substances, and iron oxides, which reduce the friction and wear of metal surfaces.

Different Dimensional Copper-Based Metal–Organic Frameworks with Enzyme-Mimetic Activity for Antibacterial Therapy

Fighting against bacterial infection and accelerating wound healing remain important and challenging in infected wound care. Metal-organic frameworks (MOFs) have received much attention for their optimized and enhanced catalytic performance in different dimensions of these challenges. The size and morphology of nanomaterials are important in their physiochemical properties and thereby their biological functions. Enzyme-mimicking catalysts, based on MOFs of different dimensions, display varying degrees of peroxidase (POD)-like activity toward hydrogen peroxide (H2O2) decomposition into toxic hydroxyl radicals (•OH) for bacterial inhibition and accelerating wound healing. In this study, we investigated the two most studied representatives of copper-based MOFs (Cu-MOFs), three-dimensional (3D) HKUST-1 and two-dimensional (2D) Cu-TCPP, for antibacterial therapy. HKUST-1, with a uniform and octahedral 3D structure, showed higher POD-like activity, resulting in H2O2 decomposition for •OH generation rather than Cu-TCPP. Because of the efficient generation of toxic •OH, both Gram-negative Escherichia coli and Gram-positive methicillin-resistant Staphylococcus aureus could be eliminated under a lower concentration of H2O2. Animal experiments indicated that the as-prepared HKUST-1 effectively accelerated wound healing with good biocompatibility. These results reveal the multivariate dimensions of Cu-MOFs with high POD-like activity, providing good potential for further stimulation of specific bacterial binding therapies in the future.

Catechol detection based on a two-dimensional copper-based metal-organic framework with high polyphenol oxidase activity

In this work, a novel sensing strategy for catechol was successfully developed based on a two-dimensional copper-based metal-organic framework (2D Cu-MOF) with high polyphenol oxidase activity. The 2D Cu-MOF was prepared from dimethylimidazole and Cu 2+ by stirring in a mixture solvent of methanol and water. We firstly found that the 2D Cu-MOF exhibited high polyphenol oxidase (PPO) activity by catalyzing the typical PPO substrate to produce a red color. And the PPO activity of the 2D Cu-MOF was higher than those of the other two reported PPO-mimicking enzymes at the same mass concentration. Subsequently, based on the effective PPO activities of the 2D Cu-MOF, we established a simple and rapid colorimetric method for detecting catechol with a detection limit of 0.35 μg·mL −1 . This method was also used to detect catechol in city water with satisfying results.

Automated Graph Neural Networks Accelerate the Screening of Optoelectronic Properties of Metal–Organic Frameworks

The numerous organic and inorganic components of metal-organic framework (MOF) materials provide intriguing optoelectronic properties. Accurately predicting the electronic structural properties of MOFs has become the main focus. This work establishes two graph neural network models, crystal graph convolutional neural networks and a materials graph network, for predicting the band gaps of more than 10 000 MOF structures and promotes to improve the prediction accuracy through automatic hyperparameter tuning algorithms. Subsequently, for exploring machine learning-assisted screening of MOFs for the broader electronic properties, the screened copper-based MOFs are compared with lead-based MAPbI3 solar cells with respect to the band gaps, densities of states, and charge density distributions, and the results have demonstrated that the overlap of the wave functions between the initial and final states of MOFs is weakened, which is conducive to the improvement of photoelectric performance. The chlorine doping strategy further enhances the advantage. The tuning of the machine learning model and hyperparameters and the doping strategy of halogen elements furnish empirical rules for the design of MOFs with excellent optoelectronic properties.

Phenolic Compounds Removal from Olive Mill Wastewater Using the Composite of Activated Carbon and Copper-Based Metal-Organic Framework.

As the industry of olive oil continues to grow, the management of olive mill wastewater (OMW) by-products has become an area of great interest. While many strategies for processing OMW have been established, more studies are still required to find an effective adsorbent for total phenolic content uptake. Here, we present a composite of a Cu 1,4-benzene dicarboxylate metal-organic framework (Cu (BDC) MOF) and granular activated carbon (GAC) as an adsorbent for total phenolic content removal from OMW. Experimental results demonstrated that the maximum adsorption capacity was 20 mg/g of total phenolic content (TPC) after 4 h. using 2% wt/wt of GAC/Cu (BDC) MOF composite to OMW at optimum conditions (pH of 4.0 and 25 °C). The adsorption of phenolic content onto the GAC/Cu (BDC) MOF composite was described by the Freundlich adsorption and pseudo-second-order reaction. The adsorption reaction was found to be spontaneous and endothermic at 298 K where ΔS° and ΔH° were found to be 0.105 KJ/mol and 25.7 kJ/mol, respectively. While ΔGº value was -5.74 (kJ/mol). The results of this study provide a potential solution for the local and worldwide olive oil industry.

A New 2D Metal-Organic Framework for Photocatalytic Degradation of Organic Dyes in Water

Two-dimensional (2D) metal-organic frameworks (MOFs) are fascinating photocatalytic materials because of their unique physical and catalytic properties. Herein, we report a new (E)-4-(3-carboxyacrylamido) benzoic acid [ABA–MA] ligand synthesized under facile conditions. This ABA–MA ligand is further utilized to synthesize a copper-based 2D MOF via the solvothermal process. The resulting 2D MOF is characterized for morphology and electronic structural analysis using advanced techniques, such as proton nuclear magnetic resonance, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and scanning electron microscopy. Furthermore, 2D MOF is employed as a photocatalyst for degrading organic dyes, demonstrating the degradation/reduction of methylene blue (MeBl) dye with excellent catalytic/photodegradation activity in the absence of any photosensitizer or cocatalyst. The apparent rate constant (kap) values for the catalytic degradation/reduction of MeBl on the Cu(II)–[ABA-MA] MOF are reported to be 0.0093 min−1, 0.0187 min−1, and 0.2539 min−1 under different conditions of sunlight and NaBH4. The kinetics and stability evaluations reveal the noteworthy photocatalytic potential of the Cu(II)–[ABA–MA] MOF for wastewater treatment. This work offers new insights into the fabrication of new MOFs for highly versatile photocatalytic applications.

Constructing MOF-199 anchored RuMoP nanoparticles as a high-performance catalyst for boosting the hydrolysis of AB

Porous octahedral copper-based metal organic framework MOF-199 anchored with Ru, RuMo, RuP, and RuMoP nanoparticles (NPs) was fabricated by a simple liquid impregnation method and applied as a high-performance catalyst for the hydrolysis of ammonia borane (AB) at room temperature. Comparison of the catalytic activities of Ru@MOF-199, RuMo@MOF-199, RuP@MOF-199, and commercial Ru/C shows that RuMoP@MOF-199 owns a very high turnover frequency of 735.6 mol H2 min−1 (mol Ru)−1 and a low activation energy of 46.9 kJ/mol. Loading RuMoP NPs onto MOF-199 owing to synergistic effects, functional, size, and support effects kinetically facilitates the oxidative cleavage of attacked H-OH and elevate the catalytic performance. Moreover, this catalyst shows satisfied durability after five cycles for the hydrolytic dehydrogenation of AB. The novel structural features and efficient performance would provide an essential reference for the utilization of high-performance catalyst development.

Hierarchical copper-based metal-organic frameworks nanosheet assemblies for electrochemical ascorbic acid sensing

Noninvasive human health monitoring requires the development of efficient electrochemical sensors for the quantitative analysis of infinitesimal biomolecules. In this work, we reported a novel hierarchical nanosheet assemblies (HSA) of copper-based metal-organic frameworks (MOFs) as an electrochemical sensor for ascorbic acid (AA) detection. Copper 1,4-benzenedicarboxylate (CuBDC) HSA was constructed by three steps of in situ growth on stone paper, including hydrolysis, anion exchange, and heteroepitaxy growth. The monodispersed two-dimensional MOFs nanosheet units were aligned in an orderly manner and arranged into three-dimensional hierarchical assemblies. The CuBDC HSA-based AA sensor displayed a high sensitivity of 396.8 μA mM-1 cm-2 and a low detection limit of 0.1 μM. Excellent selectivity, stability and reproducibility were also obtained. Benefiting from the advantages of ultrathin nanosheets and nature-inspired hierarchy, this unique architecture facilitated reactant dispersion and maximized the accessible active sites and charge-transport capability and thus had superior catalytic ability for the electro-oxidation of ascorbic acid compared to bulk MOFs. Moreover, the CuBDC HSA sensor performed AA level detection in juice samples with acceptable accuracy and verified the feasibility for sweat AA sensing. This novel MOFs architecture holds great potential as an electrochemical sensor to detect AA for noninvasive human health monitoring in the future.

Copper-Based Metal–Organic Frameworks (MOFs) as an Emerging Catalytic Framework for Click Chemistry

In the extensive terrain of catalytic procedures for the synthesis of organic molecules, metal–organic frameworks (MOFs) as heterogenous catalysts have been investigated in a variety of chemical processes, including Friedel–Crafts reactions, condensation reactions, oxidations, and coupling reactions, and utilized owing to their specific properties such as high porosity, tuneability, extraordinary catalytic activity, and recyclability. The eminent copper-tailored MOF materials can be exceptionally dynamic and regioselective catalysts for click reactions (1,3-dipolar cycloaddition reaction). Considering the fact that Cu(I)-catalyzed alkyne–azide cycloaddition (CuAAC) reactions can be catalyzed by several other copper catalysts such as Cu (II)-β-cyclodextrin, Cu(OAc)2, Fe3O4@SiO2, picolinimidoamide–Cu(II) complex, and Cu(II) porphyrin graphene, the properties of sorption and reusability, as well as the high density of copper-MOFs, open an efficient and robust pathway for regimented catalysis of this reaction. This review provides a comprehensive description and analysis of the relevant literature on the utilization of Cu-MOFs as catalysts for CuAAC ‘click’ reactions published in the past decade.

Exploitation of multi-walled carbon nanotubes/Cu(ii)-metal organic framework based glassy carbon electrode for the determination of orphenadrine citrate.

Metal organic frameworks (MOFs), with structural tunability, high metal content and large surface area have recently attracted the attention of researchers in the field of electrochemistry. In this work, an unprecedented use of multi-walled carbon nanotubes (MWCNTs)/copper-based metal-organic framework (Cu-BTC MOF) composite as an ion-to-electron transducer in a potentiometric sensor is proposed for the determination of orphenadrine citrate. A comparative study was conducted between three proposed glassy carbon electrodes, Cu-MOF, (MWCNTs) and MWCNTs/Cu-MOF composite based sensors, where Cu-MOF, MWCNTs and their composite were utilized as the ion-to-electron transducers. The sensors were developed for accurate and precise determination of orphenadrine citrate in pharmaceutical dosage form, spiked real human plasma and artificial cerebrospinal fluid (ACSF). The sensors employed β-cyclodextrin as a recognition element with the aid of potassium tetrakis(4-chlorophenyl)borate (KTpCIPB) as a lipophilic ion exchanger. The sensors that were assessed based on the guidelines recommended by IUPAC and demonstrated a linear response within the concentration range of 10-7 M to 10-3 M, 10-6 M to 10-2 M and 10-8 M to 10-2 M for Cu-MOF, MWCNTs and MWCNTs/Cu-MOF composite based sensors, respectively. MWCNTs/Cu-MOF composite based sensor showed superior performance over other sensors regarding lower limit of detection (LOD), wider linearity range and faster response. The sensors demonstrated their potential as effective options for the analysis of orphenadrine citrate in quality control laboratories and in different healthcare activities.

A Cu(II) MOF with laccase-like activity for colorimetric detection of 2,4-dichlorophenol and p-nitrophenol.

Metal-organic framework (MOF) materials with aqueous stability have a good potential application in the field of mimetic enzymes. However, most of them have poor robustness in aqueous solution due to competitive coordination effects between water molecules and central metal ions. Herein, a copper-based MOF (Cu-SM MOF) was prepared using copper ions and 5-(sulfomethyl) isophthalic acid (5-SMIPA) by a hydrothermal process. Considering the similarity of coordination and morphology with HKUST-1, the aqueous stability and laccase-like activity of the Cu-SM MOF were investigated using HKUST-1 as the reference. The Cu-SM MOF shows superior aqueous stability to HKUST-1 after immersion in buffer solutions, especially under alkaline conditions. Moreover, the Cu-SM MOF possesses higher catalytic activity than HKUST-1 at a high salt concentration, high temperature, etc., because the Cu-SM MOF exhibits lower Km and higher Vmax values than those of laccase and reported mimetic enzymes. The mimetic enzyme behavior of the Cu-SM MOF is demonstrated in the oxidation of phenols, as well as in the detection of 2,4-dichlorophenol (2,4-DP) and p-nitrophenol with linear ranges of 1-100 μM and 2-250 μM, and limits of detection of 0.53 μM and 1.62 μM, respectively. Owing to the excellent aqueous stability and laccase-like activity of the Cu-SM MOF, it has great application prospects in many fields, such as the determination of phenols and the treatment of industrial wastewater.

Copper-based metal–organic frameworks for CO2reduction: selectivity trends, design paradigms, and perspectives

We relate Cu MOF structure to electrocatalytic performance and outline new lines of inquiry, challenges, and perspectives.

Adsorptive removal of tetracycline and methylene blue from aqueous solution with a water resistance copper-based metal–organic framework

Copper-1,3,5-benzenetricarboxylic acid (Cu–BTC) is a research hotspot for metal–organic frameworks (MOFs) because of its remarkable intrinsic structural features.