Dicarboxylate Metal Organic Framework Research Articles

Solvent-exchange-assisted activation of Cu-1,4-benzene dicarboxylate metal-organic framework for use as a bifunctional water splitting electrocatalyst

The activation of metal-organic frameworks (MOFs) to eliminate extra-coordinating and pore-filling solvent molecules is essential before using MOFs in catalysis applications. Herein, we developed a solvent-exchange-assisted technique to activate cathodically electrodeposited MOF containing Cu nodes and 1,4-benzene dicarboxylate (BDC) linkers, known as Cu(BDC). This method was initially executed by washing electrodeposited MOF film in ethanol and acetone, followed by soaking in dichloromethane and applying heat treatment at a low temperature to remove strongly coordinating N,N-dimethylformamide (DMF) molecules, thereby properly accessing a well-arranged mesoporous architecture with abundant active sites toward electrocatalysis. The emergence of open-state Cu centers through this safe activation method offers a catalyst with enhanced electrocatalytic performance that displays low overpotentials of only 212 mV and 341 mV at a current density of 10 mA.cm−2 toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Importantly, this study paves a way for developing low-cost methods for production and activation of MOFs for high efficient and stable alkaline water splitting.

Synthesis of Cu-1,4-Benzene Dicarboxylate Metal-Organic Frameworks (Cu-BDC MOFs) from Plastic Waste and Its Application as Catalyst in Biodiesel Production

The increasing of PET plastic waste causes various environmental problems because decomposing it is difficult to compose. This study aims to utilize PET plastic waste as a source of terephthalic acid organic linker in the solvothermal synthesis of Cu-1,4-Benzene Dicarboxylate metal-organic frameworks (Cu-BDC MOFs). Cu-BDC MOFs were characterized using FTIR, XRD, and SEM-EDX. The characterization results showed that the crystals of Cu-BDC MOFs had an irregular cubic morphology with an average crystal size of 67.96 nm. Furthermore, Cu-BDC MOFs were applied as catalysts for the esterification reaction to produce biodiesel from coconut oil. The conversion percentage of free fatty acids in the esterification process was 43.75 %, while in the transesterification process, it was 68.90 %. Analysis using GC-MS showed the presence of 8 peaks, with the largest percentage of areas identified as fatty acid methyl esters. The major components were methyl laurate (31.17 %), methyl myristate (18.77 %), methyl palmitate (12.50 %), methyl caprylate (10.76 %), methyl elaidate (10.07 %), methyl caprate (7.34 %), methyl stearate (5.67 %), and methyl linoleate (2.26 %). The quality of the biodiesel was tested, and the results were as follows: The density parameter was measured at 842.5 kg/m3, the viscosity measurement showed 2.9572 cSt, and the water content was found to be 0.09 %. Additionally, the acid number parameter was determined to be 0.2799 mg-KOH/g. HIGHLIGHTS Cu-BDC MOFs are produced through the hydrolysis of PET waste using a solvothermal mixture of distilled water, ethanol, and DMF at 85 °C for 24 h. The micrograph of the synthesized Cu-BDC MOFs reveals a clustered topography of Cu-BDC MOFs crystals with irregular cubic (hexahedral) shapes. FTIR analysis of biodiesel displays distinctive peaks corresponding to the -C-H, -C=O, -CH2, -CH3, and -C-O functional groups. The GC-MS analysis of biodiesel from coconut oil shows the presence of 8 major peaks, namely methyl caprylate, methyl caprate, methyl laurate, methyl myristate, methyl palmitate, methyl linoleate, methyl elaidate, and methyl stearate, with the largest percent area. The quality test results of biodiesel indicate a density parameter of 842.5 kg/m3, a biodiesel viscosity measurement of 2.9572 cSt, a water content of 0.0898 %, and an acid number of 0.2799 mg-KOH/g. GRAPHICAL ABSTRACT

Adsorption investigation of a composite of metal-organic framework and polyethylene oxide hydrogel

Though adsorption techniques are eco-environmentally friendly, most lack the effectiveness of complete contaminant elimination leading to increasing concerns about the presence of aqueous contaminants on humans. Thus, synergistic combination of low adsorption capacity adsorbents may be an effective method to enhance their aqueous contaminant uptake. Sol-gel synthesized lanthanum-1,4-benzene dicarboxylate metal organic framework (LaBDC MOF) and polyethylene oxide (PEO) hydrogel were combined to prepare a synergistic composite adsorbent (PEO-LaBDC) for aqueous methylene blue (MB) adsorption. Major properties of the pristine LaBDC MOF and PEO hydrogel were expressed in the characterized composite indicating successful preparation. PEO-LaBDC composite MB removal rate of MB was at least twice as fast (60 min) to those of the pristine LaBDC MOF (120 min) and PEO hydrogel (125 min). The fitting of kinetics model was fractal in nature, and optimum adsorption was on the alkaline end of the pH spectrum for all adsorbents (pH = 12, 10, and 10, respectively). Comparatively, the composite exhibited a better adsorption performance of ≈177% higher than the pristine LaBDC MOF; buttressing the idea that synergistic combination of adsorbents in composites could enhance adsorption processes. Therefore, the PEO-LaBDC composite is a promising adsorbent for the remediation of aqueous MB.

Effectiveness application of Chitosan/Alginic/Copper–organic framework beads on removal of carbaryl carbamate from wastewater

In this study, we concentrated on creating copper-benzene dicarboxylate metal organic frameworks (Cu-BDC MOFs) utilizing scrap copper metal that was obtained from used copper electrical wires. For practical applications, powdered forms of MOFs are typically poorly processed; as a result, Cu-BDC/chitosan/alginic beads were created by cross-linking chitosan, alginic acid, and Cu-BDC MOF. The carbaryl pesticide adsorption from wastewater still challenge due to its low adsorption capacity. Therefore, Copper-BDC/chitosan/alginic beads were compared to chitosan/alginic beads, and the results showed that the latter had a more effective adsorption capacity (225.51 mg g−1) than the former (95.71 mg g−1). Through the use of X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), and Brunauer-Emmett-Teller (BET), the physical and chemical properties of chitosan/alginic and Cu-BDC/chitosan/alginic beads were examined. It's interesting to note that the Cu-BDC/chitosan/alginic beads' morphology is homogeneous and has sizable holes. The uniqueness of the produced materials lends itself to desirable characteristics for the targeted isolation of carbaryl from wastewater. As a result of the current work, MOFs materials for the selective removal of pesticides from wastewater will commercially available and easily process.

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.

In situ synthesis of Cu(II) dicarboxylate metal organic frameworks (MOFs) and their application as battery materials.

New materials for battery electrodes are paramount to ensuring future battery supply can meet the ever-increasing demand for energy storage. Furthermore, detailed investigation on the various physical and chemical aspects of these materials is required to allow the same level of nuanced microstructural and electrochemical tuning that is available for conventional electrode materials. Here a comprehensive investigation is undertaken on the poorly understood in situ reaction between dicarboxylic acids and the copper current collector that occurs during electrode formulation, using a series of simple dicarboxylic acids. Specifically, we focus on the relationship between the extent of the reaction and the properties of the acid. Additionally, the extent of the reaction was demonstrated to affect both the electrode microstructure and the electrochemical performance. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and small and ultra-small angle neutron scattering (U/SANS) are used to provide unprecedented detail on the microstructure ultimately leading to a deeper understanding of formulation based performance enhancing techniques. Ultimately, it was determined that the copper-carboxylates are the active material, not the parent acid, and in some cases i.e., copper malate, capacities as high as 828 mA h g-1 were achieved. This work lays the foundation for future studies that use the current collector as an "active" component in electrode formulation and function rather than simply an inactive component of a battery.

Engineering of Metal–Organic Frameworks/Gelatin Hydrogel Composites Mediated by the Coacervation Process for the Capture of Acetic Acid

A novel strategy is proposed to synthesize metal–organic framework (MOF)–gelatin bionanocomposites by taking profit of the thermo-reversible character of gelatin and the liquid–liquid phase separation process, that is, coacervation. This enables the formation of bionanocomposites based on a series of chemically stable Zr4+ dicarboxylate MOFs (UiO-66 and MOF-801) differing by their hydrophilic–hydrophobic balance and their chemical functionality. Bionanocomposites with homogeneous and uniform distribution of MOF particles in the gelatin matrix as well as a high MOF loading (up to 90%) without compromising their porosity were prepared as a result of an excellent physico-chemical matching between MOFs and gelatin. Finally, this series of bionanocomposites were shaped into films or monoliths, and they have shown high performance for the selective adsorption of acetic acid in the presence of humidity. These composites can be regarded as highly efficient adsorbents for cultural heritage preservation.

Trans-Cis Kinetic Study of Azobenzene-4,4'-dicarboxylic Acid and Aluminium and Zirconium Based Azobenzene-4,4'-dicarboxylate MOFs.

Metal organic frameworks (MOFs) are porous hybrid crystalline materials that consist of organic linkers coordinated to metal centres. The trans–cis isomerisation kinetics of the azobenzene-4,4′-dicarboxylic acid (AZB(COOH)2) precursor, as well as the Al3+ (Al-AZB)- and Zr4+ (Zr-AZB)-based MOFs with azobenzene-4,4′-dicarboxylate linkers, are presented. The photo-isomerization in the MOFs originates from singly bound azobenzene moieties on the surface of the MOF. The type of solvent used had a slight effect on the rate of isomerization and half-life, while the band gap energies were not significantly affected by the solvents. Photo-responsive MOFs can be classified as smart materials with possible applications in sensing, drug delivery, magnetism, and molecular recognition. In this study, the MOFs were applied in the dye adsorption of congo red (CR) in contaminated water. For both MOFs, the UV-irradiated cis isomer exhibited a slightly higher CR uptake than the ambient-light exposed trans isomer. Al-AZB displayed a dye adsorption capacity of over 95% for both the UV-irradiated and ambient light samples. The ambient light exposed Zr-AZB, and the UV irradiated Zr-AZB had 39.1% and 44.6% dye removal, respectively.

Aqueous Flow Reactor and Vapour-Assisted Synthesis of Aluminium Dicarboxylate Metal-Organic Frameworks with Tuneable Water Sorption Properties.

Energy‐efficient indoors temperature and humidity control can be realised by using the reversible adsorption and desorption of water in porous materials. Stable microporous aluminium‐based metal–organic frameworks (MOFs) present promising water sorption properties for this goal. The development of synthesis routes that make use of available and affordable building blocks and avoid the use of organic solvents is crucial to advance this field. In this work, two scalable synthesis routes under mild reaction conditions were developed for aluminium‐based MOFs: (1) in aqueous solutions using a continuous‐flow reactor and (2) through the vapour‐assisted conversion of solid precursors. Fumaric acid, its methylated analogue mesaconic acid, as well as mixtures of the two were used as linkers to obtain polymorph materials with tuneable water sorption properties. The synthesis conditions determine the crystal structure and either the MIL‐53 or MIL‐68 type structure with square‐grid or kagome‐grid topology, respectively, is formed. Fine‐tuning resulted in new MOF materials thus far inaccessible through conventional synthesis routes. Furthermore, by varying the linker ratio, the water sorption properties can be continuously adjusted while retaining the sigmoidal isotherm shape advantageous for heat transformation and room climatisation applications.

Kinetic Control of Interpenetration in Fe–Biphenyl-4,4′-dicarboxylate Metal–Organic Frameworks by Coordination and Oxidation Modulation

Phase control in the self-assembly of metal-organic frameworks (MOFs) is often a case of trial and error; judicious control over a number of synthetic variables is required to select the desired topology and control features such as interpenetration and defectivity. Herein, we present a comprehensive investigation of self-assembly in the Fe-biphenyl-4,4'-dicarboxylate system, demonstrating that coordination modulation can reliably tune between the kinetic product, noninterpenetrated MIL-88D(Fe), and the thermodynamic product, two-fold interpenetrated MIL-126(Fe). Density functional theory simulations reveal that correlated disorder of the terminal anions on the metal clusters results in hydrogen bonding between adjacent nets in the interpenetrated phase and this is the thermodynamic driving force for its formation. Coordination modulation slows self-assembly and therefore selects the thermodynamic product MIL-126(Fe), while offering fine control over defectivity, inducing mesoporosity, but electron microscopy shows MIL-88D(Fe) persists in many samples despite not being evident by diffraction. Interpenetration control is also demonstrated using the 2,2'-bipyridine-5,5'-dicarboxylate linker; it is energetically prohibitive for it to adopt the twisted conformation required to form the interpenetrated phase, although multiple alternative phases are identified due to additional coordination of Fe cations to its N donors. Finally, we introduce oxidation modulation-the use of metal precursors in different oxidation states from that found in the final MOF-to kinetically control self-assembly. Combining coordination and oxidation modulation allows the synthesis of pristine MIL-126(Fe) with BET surface areas close to the predicted maximum for the first time, suggesting that combining the two may be a powerful methodology for the controlled self-assembly of high-valent MOFs.

Vapour-phase deposition of oriented copper dicarboxylate metal-organic framework thin films.

Copper dicarboxylate metal-organic framework films are deposited via chemical vapour deposition. Uniform films of CuBDC and CuCDC with an out-of-plane orientation and accessible porosity are obtained from the reaction of Cu and CuO with vaporised dicarboxylic acid linkers.

A base-stable metal-organic framework for sensitive and non-enzymatic electrochemical detection of hydrogen peroxide

Stability of metal-organic frameworks (MOFs) in aqueous medium and extreme solution conditions (acidic or basic) are important for the development of stable, reproducible, and sensitive electrochemical biosensors. Herein, a base-stable chromium(III) dicarboxylate MOF was synthesized by microwave assisted solvothermal method for non-enzymatic detection of hydrogen peroxide (H2O2). The as-synthesized MOF exhibited excellent base stability without any obvious changes in crystallinity, morphology, and spectroscopic behaviors after base treatment. This MOF-modified glassy carbon electrode showed negligible change in charge transfer resistance at the electrode|electrolyte interface after redox cycling and good catalytic activity for the reduction of H2O2 in 0.1 M NaOH(aq.). The enhanced catalytic activity of H2O2 reduction is enabled by the redox process of CrIII/II in the chromium (III) dicarboxylate. The sensor showed the sensitivity of ca. 11.9 μA mM−1, wide linear range from 25 to 500 μM, and a method detection limit of ca. 3.52 μM. The validation of this sensing platform was evaluated by standard addition method. Thus, the present biosensor could be used for the point of care detection of H2O2.

A Flexible Fluorescent Zr Carboxylate Metal–Organic Framework for the Detection of Electron-Rich Molecules in Solution

A novel Zr(IV) dicarboxylate metal organic framework (MOF) built up from an s-tetrazine derived ligand was prepared. This solid, which exhibits a diamond type network, combines a good stability in water, a structural flexibility, and fluorescence properties thanks to the organic ligand. It is noteworthy that this fluorescence is quenched when exposed to electron-rich molecules in solution, such as amines or phenol, this phenomenon being associated with the adsorption of the quencher, as unambiguously proven by X-ray diffraction (XRD) analysis. Finally, the quenching efficiency is shown to be governed not only by electronic and steric factors but also by the relative polarity of the solvent, the MOF, and the quencher. This work thus suggests that it is possible to develop new MOF-based sensors presenting in a given medium (such as water) highly selective responses.

Metal organic framework-laden composite polymer electrolytes for efficient and durable all-solid-state-lithium batteries

A copper benzene dicarboxylate metal organic framework (Cu-BDC MOF) was synthesized and successfully incorporated in a poly(ethylene oxide) (PEO) and lithium bis(trifluoromethanesulfonylimide) (LiTFSI) complex.

Bimetallic–Organic Framework as a Zero‐Leaching Catalyst in the Aerobic Oxidation of Cyclohexene

AbstractA gallium 2,2′‐bipyridine‐5,5′‐dicarboxylate metal–organic framework (MOF), denoted as COMOC‐4, has been synthesized by solvothermal synthesis. This MOF exhibits the same topology as MOF‐253. CuCl2 was incorporated into COMOC‐4 by a post‐synthetic modification (PSM). The spectroscopic absorption properties of the MOF framework before and after PSM were compared with theoretical data obtained by employing molecular dynamics combined with time‐dependent DFT calculations on both the as‐synthesized and functionalized linker. The catalytic behavior of the resulting Cu2+@COMOC‐4 material was evaluated in the aerobic oxidation of cyclohexene with isobutyraldehyde as a co‐oxidant. In addition, the catalytic performance of Cu2+@COMOC‐4 was compared with that of the commercially available Cu‐BTC (BTC=benzene‐1,3,5‐tricarboxylate) MOF. Cu2+@COMOC‐4 exhibits a good cyclohexene conversion and an excellent selectivity towards cyclohexene oxide in comparison to the Cu‐based reference catalyst. Furthermore, no leaching of the active Cu sites was observed during at least four consecutive runs.

Bipyridine-Based Nanosized Metal–Organic Framework with Tunable Luminescence by a Postmodification with Eu(III): An Experimental and Theoretical Study

A gallium 2,2′-bipyridine-5,5′-dicarboxylate metal–organic framework, Ga(OH)(bpydc), denoted as COMOC-4 (COMOC = Center for Ordered Materials, Organometallics and Catalysis, Ghent University) has been synthesized via solvothermal synthesis procedure. The structure has the topology of an aluminum 2,2′-bipyridine-5,5′-dicarboxylate – the so-called MOF-253. TEM and SEM micrographs show the COMOC-4 crystals are formed in nanoplates with uniform size of 30–50 nm. The UV–vis spectra of COMOC-4 in methanol solution show maximal electronic absorption at 307 nm. This results from linker to linker transitions as elucidated by time-dependent density functional theory simulations on the linker and COMOC-4 cluster models. When excited at 400 nm, COMOC-4 displays an emission band centered at 542 nm. Upon immersion in different solvents, the emission band for the framework is shifted in the range of 525–548 nm depending on the solvent. After incorporating Eu3+ cations, the emission band of the framework is shifted to ev...