Organic Linkers Research Articles

The Ag based composites derived from Ag-MOFs with tunable forms for electromagnetic wave absorption

The wireless communication and network technology make our lives more and more convenient. However, the inevitable electromagnetic pollution and interference deriving from these technologies have hazardous influences on the electronic equipment and human health. Therefore, continuous explorations have been strived to fabricate excellent electromagnetic wave (EMW) absorbers to diminish the impact of these negative effects. MOF, as an emerging hybrid material is widely investigated as the EMW absorber due to its multiple attenuation mechanisms. However, attentions are always focused on the influence of different inorganic ions and organic linkers on the electromagnetic wave absorption (EMWA) performance of MOF. Significantly, tremendous facts have proved that the control of morphologies and forms of hybrid materials is vital for further enhancement of many applications. Hence, the investigation of effect of MOF forms on EMWA performance will be the important foundation for further explorations. Here, three different forms of Ag based MOFs, named Ag-MOF, Ag-MOF-Microcrystal and Ag-MOG were successfully fabricated. Further investigations of XPS, XRD as well as FT-IR manifested that these three materials had the same coordination behaviors. The different forms could be obtained by the controlling of crystallization. Ag-MOG was proved to be the best EMW absorber among the fabricated materials. The minimum RL of −41.8 dB and a wider EAB of 6.3 GHz could be obtained by Ag-MOG derived composite.

Cu-Metalated Porphyrin-Based MOFs Coupled with Anatase as Photocatalysts for CO2 Reduction: The Effect of Metalation Proportion

Converting carbon dioxide (CO2) into valuable chemicals such as fossil resources via photocatalysis requires the development of advanced materials. Herein, we coupled zirconium-based metal–organic frameworks (MOFs) containing porphyrin and Cu-porphyrin with anatase TiO2. The effect of the porphyrin metalation proportion was also investigated. Notably, while the use of free-base porphyrin as the organic linker resulted in the development of PCN-224, the presence of Cu-porphyrin provided mixed-phase MOF structures containing both PCN-224 and PCN-222. MOF/TiO2 composites bearing partial (50%) metalated porphyrin were proven more active and selective towards the production of CH4, at ambient conditions, in the gas phase and using water vapors without the use of hole scavengers. The optimized composite bearing 15 wt.% of the partial metalated MOF was three times more active than pure TiO2 towards CH4 production. This study provides insights on the effect of precise materials engineering at a molecular level on the development of advanced MOF-based photocatalysts for CO2 reduction.

A 5-fold Interpenetrated and Porous Dia-net Metal-Organic Framework Constrcuted from Long and Linear Phenyl-carboxylate Linkers

Interpenetration regulation is of great significance for both the crystal engineering and functional chemistry of MOFs. The combination of long and linear ditopic organic linkers with single or small metal node is effective to produce interpenetration metal-organic framework. Here, a 5-fold interpenetrated and porous dia-net metal-organic framework of [Cd(tpdc)2 ]·3DMF (Cd-MOF, H2 tpdc = 2′,5′-dimethylterphenyl-4,4″-dicarboxylate) was synthesizd under solvothermal reaction, which was structurally characterizaed by single X-ray crystal diffraction, coupled with thermal and luminescence properties study. The compound crystallises in monoclinic P2/c space group with cell parameters of a = 15.7789(4) Å, b = 24.8437(7) Å, c = 26.3720(4) Å, α = 90o , β = 96.5583(19)o , γ = 90o , and V = 23967 Å3 There are 1D channels and porosity of 57.5% for the Cd-MOF, which is a rare example of MOFs with coexistence of high-degree interpenetration and high porosity. The MOF can thermally stable up to 360 o C, with light blue lumiscent emission at 360 nm under a ultraviolet radiation.

Cobalt sulfide flower-like derived from metal organic frameworks on nickel foam as an electrode for fabrication of asymmetric supercapacitors

Metal–organic frameworks, as a kind of advanced nanoporous materials with metal centers and organic linkers, have been applied as promising electrode materials in energy storage devices. In this study, we are successfully prepared cobalt sulfide nanosheets (CoS) derived from the metal–organic framework on nickel foam (NF). The prepared electrodes are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller and Barrett-Joyner-Halenda and electrochemical methods like voltammetry, galvanostatic charge–discharge curve and electrochemical impedance spectroscopy. The CoS/NF electrode demonstrates a high specific capacity of 377.5 mA h g−1 (1359 C g−1) at the current density of 2 A g−1, considerable rate performance and excellent durability (89.4% after 4000 cycles). A hybrid supercapacitor is assembled using CoS/NF as the positive electrode and activated carbon as the negative electrode, it shows a high energy density of 57.4 W h kg−1 at a power density of 405.2 W kg−1. The electrochemical results suggest that the CoS nanosheet arrays would possess excellent potential for applications in energy storage devices.

Energy Storage Performance of Electrode Materials Derived from Manganese Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) are porous materials assembled using metal and organic linkers, showing a high specific surface area and a tunable pore size. Large portions of metal open sites in MOFs can be exposed to electrolyte ions, meaning they have high potential to be used as electrode materials in energy storage devices such as supercapacitors. Also, they can be easily converted into porous metal oxides by heat treatment. In this study, we obtained high energy storage performance by preparing electrode materials through applying heat treatment to manganese MOFs (Mn-MOFs) under air. The chemical and structural properties of synthesized and thermally treated Mn-MOFs were measured by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The surface area and porosity were investigated by nitrogen adsorption/desorption isotherms. The electrochemical properties were studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) using a three-electrode cell. It was found that Mn-MOF electrodes that underwent heat treatment at 400 °C under air consisted of Mn2O3 with high specific surface area and porosity. They also showed a superior specific capacitance of 214.0 F g-1 and an energy density value of 29.7 Wh kg-1 (at 0.1 A g-1) compared to non-treated Mn-MOFs.

Coarse-Grained Crystal Graph Neural Networks for Reticular Materials Design.

Reticular materials, including metal-organic frameworks and covalent organic frameworks, combine the relative ease of synthesis and an impressive range of applications in various fields from gas storage to biomedicine. Diverse properties arise from the variation of building units─metal centers and organic linkers─in almost infinite chemical space. Such variation substantially complicates the experimental design and promotes the use of computational methods. In particular, the most successful artificial intelligence algorithms for predicting the properties of reticular materials are atomic-level graph neural networks, which optionally incorporate domain knowledge. Nonetheless, the data-driven inverse design involving these models suffers from the incorporation of irrelevant and redundant features such as a full atomistic graph and network topology. In this study, we propose a new way of representing materials, aiming to overcome the limitations of existing methods; the message passing is performed on a coarse-grained crystal graph that comprises molecular building units. To highlight the merits of our approach, we assessed the predictive performance and energy efficiency of neural networks built on different materials representations, including composition-based and crystal-structure-aware models. Coarse-grained crystal graph neural networks showed decent accuracy at low computational costs, making them a valuable alternative to omnipresent atomic-level algorithms. Moreover, the presented models can be successfully integrated into an inverse materials design pipeline as estimators of the objective function. Overall, the coarse-grained crystal graph framework is aimed at challenging the prevailing atom-centric perspective on reticular materials design.

Multifunctional Metal-Organic Frameworks as Catalysts for Tandem Reactions.

Owing to well-defined structure as well as easy synthesis and modification, metal-organic frameworks (MOFs) have emerged as promising catalysts for tandem reactions. In this article, we aim to summarize the development of multifunctional MOFs, including mixed metal MOFs, MOFs that are synergistically catalyzed by metal nodes and organic linkers, MOFs loaded with metal nanoparticles, etc, as heterogenous catalysts for tandem reactions over the past five years. This concept briefly discusses on present challenges, future trends, and prospects of multifunctional MOFs catalysts in tandem reactions.

Facile Tailoring of Metal-Organic Frameworks for Förster Resonance Energy Transfer-Driven Enhancement in Perovskite Photovoltaics.

Förster resonance energy transfer (FRET) has demonstrated its potential to enhance the light energy utilization ratio of perovskite solar cells by interacting with metal-organic frameworks (MOFs) and perovskite layers. However, comprehensive investigations into how MOF design and synthesis impact FRET in perovskite systems are scarce. In this work, nanoscale HIAM-type Zr-MOF (HIAM-4023, HIAM-4024, and HIAM-4025) is meticulously tailored to evaluate FRET's existence and its influence on the perovskite photoactive layer. Through precise adjustments of amino groups and acceptor units in the organic linker, HIAM-MOFs are synthesized with the same topology, but distinct photoluminescence (PL) emission properties. Significant FRET is observed between HIAM-4023/HIAM-4024 and the perovskite, confirmed by spectral overlap, fluorescence lifetime decay, and calculated distances between HIAM-4023/HIAM-4024 and the perovskite. Conversely, the spectral overlap between the PL emission of HIAM-4025 and the perovskite's absorption spectrum is relatively minimal, impeding the energy transfer from HIAM-4025 to the perovskite. Therefore, the HIAM-4023/HIAM-4024-assisted perovskite devices exhibit enhanced EQE via FRET processes, whereas the HIAM-4025 demonstrates comparable EQE to the pristine. Ultimately, the HIAM-4023-assisted perovskite device achieves an enhanced power conversion efficiency (PCE) of 24.22% compared with pristine devices (PCE of 22.06%) and remarkable long-term stability under ambient conditions and continuous light illumination.

A ternary dual-emission Eu(III)-functionalized HOF/COF hybrid: Tryptophan, 5-hydroxyindoleacetic acid ratiometric fluorescence detection and latent fingerprint identification

Fluorescent covalent organic framework (COFs) and lanthanide functionalized hydrogen-bonded organic framework have been widely studied in the field of fluorescence sensing due to their excellent properties. To our knowledge, there is no report about HOF/COF composites by combining HOF and COF. In our work, we propose a simple in-situ growth method to synthesize HOF/COF by adding pre-synthesized fluorescent COF into HOF preparation system. Based on the coordination post-synthetic modification, the ternary Eu(III) functional HOF/COF hybrid material (Eu@HOF/COF) is obtained, in which partial organic linkers of HOF are transformed to a new structure induced by Eu(III). At the single excitation wavelength, Eu@HOF/COF has two emission peaks corresponding to COF and Eu(III), respectively, and its luminescence is little affected by water molecules, which is relatively rare in previous work. Eu@HOF/COF, as a ratiometric fluorescence sensor can detect tryptophan and its metabolite 5-hydroxyindoleacetic acid with high selectivity, fast response, good sensitivity and recovery. Eu@HOF/COF has good fluorescence emission of Eu(III) and COF, and a large number of free carboxyl groups of HOF react with residues in latent fingerprint (LFP), which is beneficial in LFP identification. In summary, this study not only provides a useful reference for the construction of hybrid materials with Eu(III) and COF dual-emission centers, but also reveals that the new structure formed after the coordination of Eu(III) and HOF to sensitize Eu(III) luminescence, and also has the potential for the early detection of depression and diagnosis of carcinoid tumors.

TEMPO radically expedites the conversion of sulfides to sulfoxides by pyrene-based metal-organic framework photocatalysis

Metal-organic frameworks (MOFs) are well-documented for visible light photocatalysis because of their tailorable structures and tunable absorptions through organic linkers. By employing a highly conjugated linker, 4,4’,4’’,4’’’-(pyrene-1,3,6,8-tetrayltetrakis(ethyne-2,1-diyl))tetrabenzoic acid, the optical absorption of the MOF NU-1100 is effectively tuned to visible light below 600 nm region. Under green light irradiation, NU-1100 triggers charge separation and modulates electron transfer from the linkers to the Zr6O4(OH)412+ clusters, driving the oxidation of sulfides to sulfoxides. Notably, adding a redox mediator radically expedites the oxidation of sulfides by NU-1100 photocatalysis, TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) and 4-carboxy-TEMPO. At least 2.7 and 5.2 times of conversions of phenyl methyl sulfide are achieved by NU-1100 photocatalysis with TEMPO and 4-carboxy-TEMPO, respectively. A series of characterizations illustrate that 4-carboxy-TEMPO is adsorbed onto the exterior surface of Zr6O4(OH)412+ clusters of NU-1100 to mediate hole transfer and achieve higher charge transfer efficiency. Mechanistic studies indicate that superoxide is the essential reactive oxygen species and that the oxidation of sulfides is driven by an electron transfer pathway. This study demonstrates the integration of redox mediators with MOFs can drive more efficient visible light photocatalytic reactions.

Expanding the Reticular Chemistry Building Block Library toward Highly Connected Nets: Ultraporous MOFs Based on 18-Connected Ternary, Trigonal Prismatic Superpolyhedra.

The chemistry of metal-organic frameworks (MOFs) continues to expand rapidly, providing materials with diverse structures and properties. The reticular chemistry approach, where well-defined structural building blocks are combined together to form crystalline open framework solids, has greatly accelerated the discovery of new and important materials. However, its full potential toward the rational design of MOFs relies on the availability of highly connected building blocks because these greatly reduce the number of possible structures. Toward this, building blocks with connectivity greater than 12 are highly desirable but extremely rare. We report here the discovery of novel 18-connected, trigonal prismatic, ternary building blocks (tbb's) and their assembly into unique MOFs, denoted as Fe-tbb-MOF-x (x: 1, 2, 3), with hierarchical micro- and mesoporosity. The remarkable tbb is an 18-c supertrigonal prism, with three points of extension at each corner, consisting of triangular (3-c) and rectangular (4-c) carboxylate-based organic linkers and trigonal prismatic [Fe3(μ3-Ο)(-COO)6]+ clusters. The tbb's are linked together by an 18-c cluster made of 4-c ligands and a crystallographically distinct Fe3(μ3-Ο) trimer, forming overall a 3-D (3,4,4,6,6)-c five nodal net. The hierarchical, highly porous nature of Fe-tbb-MOF-x (x: 1, 2, 3) was confirmed by recording detailed sorption isotherms of Ar, CH4, and CO2 at 87, 112, and 195 K, respectively, revealing an ultrahigh BET area (4263-4847 m2 g-1) and pore volume (1.95-2.29 cm3 g-1). Because of the observed ultrahigh porosities, the H2 and CH4 storage properties of Fe-tbb-MOF-x were investigated, revealing well-balanced high gravimetric and volumetric deliverable capacities for cryoadsorptive H2 storage (11.6 wt %/41.4 g L-1, 77 K/100 bar-160 K/5 bar), as well as CH4 storage at near ambient temperatures (367 mg g-1/160 cm3 STP cm-3, 5-100 bar at 298 K), placing these materials among the top performing MOFs. The present work opens new directions to apply reticular chemistry for the construction of novel MOFs with tunable porosities based on contracted or expanded tbb analogues.

Comment: AI Accelerates Modeling of New Materials for Carbon Capture

_ Artificial intelligence (AI) is increasingly being employed to assist in the development of materials, including metal-organic frameworks (MOFs), to develop carbon capture technologies. MOFs are modular materials made up of three building blocks: inorganic nodes such as zinc or copper; organic nodes; and organic linkers made up of carbon, oxygen, and other elements. By changing the relative positions and configurations of the building blocks, the potential combinations for creation of unique MOFs are countless. The idea is to create a porous carbon dioxide “trap” to capture carbon from the air. The structure created by the building blocks can be thought of simplistically as a scaffolding with joints (linkers) that functions to absorb carbon. In a recent paper, researchers from the US Department of Energy Argonne National Laboratory, The University of Illinois Chicago (UIC), University of Illinois, Northwestern University, and TotalEnergies described their use of generative AI to identify “good carbon absorbers” among “billions and billions of possibilities.” Although early work on developing MOFs began in the 1990s, the power of AI modeling can generate new models with desired properties such as optimal selectivity and capacity without the laborious, reiterative experimental and computational efforts once required. In a press release, Argonne said, “… The team was able to quickly assemble, building block by building block, over 120,000 new MOF candidates within 30 minutes” on a supercomputer at the Argonne Leadership Computing Facility. “The race for capturing carbon hinges on finding needles in a haystack, and trial and error is too slow. You have billions and billions of possibilities, and then you must narrow down to candidates that are good carbon absorbers,” said paper coauthor Santanu Chaudhuri, professor of civil, materials, and environmental engineering at UIC and director of manufacturing science and engineering at Argonne, in a news release. “With this project, we have taken the first significant step towards closing that gap by using generative AI.” Coauthor Eliu Huerta, an Argonne computational scientist who helped lead the study, said, “The traditional methods have typically involved experimental synthesis and computational modeling with molecular dynamics simulations. But trying to survey the vast MOF landscape in this way is just impractical. “We wanted to add new flavors to the MOFs that we were designing. We needed new ingredients for the AI recipe,” Huerta said. The AI framework, called GHP-MOFassemble, screened the newly built 120,000 MOFs in 40 minutes to identify nearly 79,000 with valid bonds (joints). Those were screened to identify 19,000 with valid chemistry within 205 minutes. From this group, 364 MOFs were identified in 50 minutes with CO2 capacity higher than a selected value. From assembly to selection of MOFs, GHP-MOFassemble completed the analysis within 5 hours and 7 minutes. Powering the AI Future It’s ironic that processing of massive volumes of data on supercomputers for emissions-related research, such as AI simulations, could contribute to the problem to be solved because of the electricity required. Supercomputers use the computing power of multiple interconnected processing cores, which require an immense amount of energy—and depending on the source of the electricity generation, also contribute to emissions. In a November 2023 commentary, International Energy Agency (IEA) analysts estimated that AI uses more energy than other forms of computing. Training a single model uses more electricity than 100 US homes consume in an entire year. In 2022, Google reported that machine learning accounted for about 15% of its total energy use over the prior 3 years. In a January report, IEA estimated that Google could see a tenfold increase in their electricity demand if AI is fully implemented in its search engine. The average electricity demand of a typical search is 0.3 Wh. OpenAI’s ChatGPT requires 2.9 Wh per request. Considering 9 billion searches per day, nearly 10 TWh of additional electricity would be required in a year. Google and other tech companies are shifting their data operations around the world daily or hourly to tap into excess renewable energy production. Google uses its “carbon-intelligent” platform to analyze day-ahead predictions of how much a given grid will be relying on carbon-intensive energy. It then shifts computing globally in favor of regions where more carbon-free electricity is available. As AI advances in modeling complexity with a greater number of parameters, there is a growing emphasis on sustainability and optimizing power consumption, including developing energy-efficient algorithms, hardware, and data center management strategies. For Further Reading A Generative Artificial Intelligence Framework Based on a Molecular Diffusion Model for the Design of Metal-Organic Frameworks for Carbon Capture by H. Park, X. Yan, and R. Zhu, et al. Communications Chemistry. Why AI and Energy Are the New Power Couple by V. Rozite, J. Miller, and S. Oh, International Energy Agency. Electricity 2024. International Energy Agency. We Now Do More Computing Where There’s Cleaner Energy by R. Koningstein, Google Research.

Effective photo-catalytic degradation of Malachite Green with water stable Cu based aliphatic di-carboxylate MOFs

Four different mesoporous Cu-MOFs named as Cu(Pima), Cu(Suba), Cu(Azla) and Cu(Seba) were prepared from aliphatic di-carboxylate linkers with the dimeric Cu paddle wheels as Secondary Building Units (SBUs). These as-synthesized aliphatic Cu-MOFs were applied as fresh heterogeneous catalysts for the catalytic wet peroxide oxidation of simulated Malachite Green waste-water and characterized using PXRD, FT-IR, Fe-SEM and BET. The results exhibited a better catalytic degradation efficiency of Cu(Seba) and Cu(Azla) (>90% in 200 mins) as compared to Cu(Pima) and Cu(Suba). It was established that degradation efficiency of Cu(seba) was approximately 9.8 times better than the rest of the synthesized Cu(MOFs). It was recognized that increasing the organic linker length can evidently boost the dye degradation process. Under optimum conditions, the degradation efficiency of 98% and 97% for Cu(Seba) and Cu(Azla) were achieved respectively. A optimal condition of 1.0 mL H2O2, 50 °C temperature and 3.5 pH was obtained. A recyclability experiment of four runs was performed for Cu(Seba) and Cu(Azla) which exhibited they maintained an effective degradation efficiency of ∼80% simulated MG solution. These analytical results of the degradation efficiency for Cu(Seba) and Cu(Azla) led us on a conclusion that, as synthesized Cu-MOFs outperformed several other reported MOFs, nanoparticles, adsorbents etc., as heterogeneous catalysts in the field of dye degradation for wastewater treatment.

Enhanced Crystallinity of MIL-53 (Fe) and Improved Pb2+ Ion Removal by MIL-53(Fe) in the Presence of TiO2

Water pollution due to improper disposal of various contaminants is one of the most serious threats faced by living beings all around the world. Lead (Pb) is a heavy metal which is commonly added to the environment by the industries such as battery manufacturing, paints etc. According to the world health organization, the maximum bearable Pb concentration of the human body is 70 μg dL- 1. However, in a contaminated water sample, this value could range from 200 to 500 mg L-1. Thus, the efficient removal of heavy metals from contaminated water is vital. Among various removal techniques available, adsorption plays a major role due to its high efficiency, low cost and ease of designing. MOFs are a class of crystalline porous adsorbent material that consists of a metal ion/cluster and an organic linker. Owing to their tailoring ability, high porosity, and high surface area they have been widely used in the removal of contaminants from wastewater. The main objectives of this study are to synthesize MIL-53 (Fe) MOF and MIL-53/TiO2 composite and determine the Pb (II) removal efficiency under light and dark conditions. MIL-53 (Fe) MOF was synthesized using iron (III) and 1, 4-dicarboxylic acid under solvothermal conditions. The composite was synthesized similarly in the presence of TiO2 nanoparticles. The successful synthesis of MIL-53 (Fe) MOF and MOF/TiO composite was confirmed by powder X-ray diffraction and Fourier-transform infrared spectroscopy. By the Debye−Scherrer equation, 79.06 nm and 65.46 nm of crystallite size were obtained by the MOF and the MOF/TiO22 composite. Atomic absorption spectroscopy was used to determine the metal ion concentration before and after adsorption. The optimum conditions for the Pb(II) removal are as; 50 mg L-1, 25 mg L-1 initial Pb ion concentration, 10 mg, 12.5 mg of adsorbent dose (for 25 ml of 50 mg L-1 Pb (II)) and 90 min, 90 min contact time for both adsorbents at light and dark conditions respectively. The pH of the solution was kept at a neutral level to ensure the reusability of wastewater after the removal of pollutants. The adsorption isotherms of both adsorbents were well fitted with the Langmuir model indicating the monolayer adsorption. Thus, at pH 7, 396.35 mg g-1 and 786.16 mg g-1 of maximum Pb (II) adsorption capacity were obtained by the MOF and the MOF/TiO2 composite respectively. Thus, a significant improvement in the Pb (II) ion removal was observed with the composite compared to the MOF. 
 Keywords: Adsorption, Heavy metal, Isotherm, MIL-53 (Fe)

Solvent-Driven Dynamics: Crafting Tailored Transformations of Cu(II)-Based MOFs.

Metal-organic frameworks (MOFs), a sort of crystalline porous coordination polymers composed of metal ions and organic linkers, have been intensively studied for their ability to take up nonpolar gas-phase molecules such as ethane and ethylene. In this context, interpenetrated MOFs, where multiple framework nets are entwined, have been considered promising materials for capturing nonpolar molecules due to their relatively higher stability and smaller micropores. This study explores a solvent-assisted reversible strategy to interpenetrate and deinterpenetrate a Cu(II)-based MOF, namely, MOF-143 (noninterpenetrated form) and MOF-14 (doubly interpenetrated forms). Interpenetration was achieved using protic solvents with small molecular sizes such as water, methanol, and ethanol, while deinterpenetration was accomplished with a Lewis-basic solvent, pyridine. Additionally, this study investigates the adsorptive separation of ethane and ethylene, which is a significant application in the chemical industry. The results showed that interpenetrated MOF-14 exhibited higher ethane and ethylene uptakes compared to the noninterpenetrated MOF-143 due to narrower micropores. Furthermore, we demonstrate that pristine MOF-14 displayed higher ethane selectivity than transformed MOF-14 from MOF-143 by identifying the "fraction of micropore volume" as a key factor influencing ethane uptake. These findings highlight the potential of controlled transformations between interpenetrated and noninterpenetrated MOFs, anticipating that larger MOF crystals with narrower micropores and higher crystallinity will be more suitable for selective gas capture and separation applications.

Laser-Induced and MOF-Derived Metal Oxide/Carbon Composite for Synergistically Improved Ethanol Sensing at Room temperature

HighlightsMetal oxide and carbon hybrids (MOx/C) were micropatterned very rapidly and energy efficiently by direct laser writing.Metal-organic framework was the ideal precursor for fabricating homogeneous MOx/C hybrids due to regularly spaced metal ions and organic ligands.The fabricated sensor not only demonstrated broad-range gas sensing capability for ethanol gas (170-3,400 ppm) but also exhibited exceptional sensitivity, rapid response and recovery, selectivity, linearity, and thermal stability.

Metal‐organic Frameworks in Semiconductor Devices

AbstractMetal‐organic frameworks (MOFs) are a specific class of hybrid, crystalline, nano‐porous materials made of metal‐ion‐based ‘nodes’ and organic linkers. Most of the studies on MOFs largely focused on porosity, chemical and structural diversity, gas sorption, sensing, drug delivery, catalysis, and separation applications. In contrast, much less reports paid attention to understanding and tuning the electrical properties of MOFs. Poor electrical conductivity of MOFs (~10−7–10−10 S cm−1), reported in earlier studies, impeded their applications in electronics, optoelectronics, and renewable energy storage. To overcome this drawback, the MOF community has adopted several intriguing strategies for electronic applications. The present review focuses on creatively designed bulk MOFs and surface‐anchored MOFs (SURMOFs) with different metal nodes (from transition metals to lanthanides), ligand functionalities, and doping entities, allowing tuning and enhancement of electrical conductivity. Diverse platforms for MOFs‐based electronic device fabrications, conductivity measurements, and underlying charge transport mechanisms are also addressed. Overall, the review highlights the pros and cons of MOFs‐based electronics (MOFtronics), followed by an analysis of the future directions of research, including optimization of the MOF compositions, heterostructures, electrical contacts, device stacking, and further relevant options which can be of interest for MOF researchers and result in improved devices performance.

Metal-organic Frameworks: Emerging Luminescent Sensors

Abstract: Metal-organic frameworks (MOFs), a crystalline material, are a new type of inorganicorganic hybrid material. MOFs are of great interest to researchers in chemistry and material science due to their various chemical and physical properties, and features include their remarkable surface area, high porosity, flexibility, structural variety, flexibility, extreme porosity, a large surface area, augmented adsorption/desorption kinetics, biocompatibility and functional tunability. MOFs are multi-dimensional crystals and have extended net-like frameworks from molecular building units such as inorganic metal nodes and organic linkers. The structurally diverse MOFs have found applications in chemical sensing and several other fields, such as energy applications, biomedicine, and catalysis. Numerous researchers from other fields have been drawn to this topic by the intrinsic potential to absorb gas molecules, which has led to the applications of gas storage and heterogeneous catalysis. Because of their low framework density, open metal sites for interaction, adjustable pore size, fast response with high sensitivity and selectivity, and real-time monitoring, luminescent metalorganic frameworks, or LMOFs, have piqued the interest of a large scientific community as a promising candidate for sensor applications. A number of characteristics, including non-toxicity, biodegradability, and reasonably priced, varied functionality, are important factors in the use of MOFs in chemo- and biosensing. MOFs can be very promising candidates as selective and sensitive chemosensors for the detection of cations, anions, small molecules, gases and explosives. In this manuscript, we address recent research advances in the use of metal-organic-framework-based luminescent sensors for detecting some small molecules and various metal ions in aqueous biological and environmental samples. A wide range of materials may be reached in the emerging field of synthetic and material chemistry, thanks to the capacity to change the pore size and chemically functionalize its nature without changing its architecture.

Preparation of manganese-based metal organic framework (MOF) and its characterization properties

Metal-organic frameworks (MOFs) are produced by the reaction of metal ions and organic linkers with extremely crystalline and porous coordination networks. The applications of MOF cover from gas purification, gas separation, catalysis and super-capacitors. This work reports on the synthesization of metal-organic framework (MOF), using mangan (II) nitrate tetrahydrate as source of metal ions, 2-methylimidazole as organic ligand and ethanol as solvent. The material was prepared using precipitation method, at room temperature for 48 hours. The characterization of this material were carried out including X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The SEM analysis shows an irregular structure with a few petals. XRD shows several peaks, indicating crystallinity of the material, and amorphous state. To study the electrochemical property of the material, Cyclic Voltammetry (CV) was conducted. The cyclic voltammetry result shows peak at 0.23 V, with current output of 0.14 μA, with no changes in peak position as the scanning rate increases from 10 to 100 mV/s.

Covalent Organic Framework Membranes and Water Treatment.

Covalent organic frameworks (COFs) are an emerging class of highly porous crystalline organic polymers comprised entirely of organic linkers connected by strong covalent bonds. Due to their excellent physicochemical properties (e.g., ordered structure, porosity, and stability), COFs are considered ideal materials for developing state-of-the-art separation membranes. In fact, significant advances have been made in the last six years regarding the fabrication and functionalization of COF membranes. In particular, COFs have been utilized to obtain thin-film, composite, and mixed matrix membranes that could achieve effective rejection (mostly above 80%) of organic dyes and model organic foulants (e.g., humic acid). COF-based membranes, especially those prepared by embedding into polyamide thin-films, obtained adequate rejection of salts in desalination applications. However, the claims of ordered structure and separation mechanisms remain unclear and debatable. In this perspective, we analyze critically the design and exploitation of COFs for membrane fabrication and their performance in water treatment applications. In addition, technological challenges associated with COF properties, fabrication methods, and treatment efficacy are highlighted to redirect future research efforts in realizing highly selective separation membranes for scale-up and industrial applications.