Metal-organic Frameworks Research Research Articles

Heavy metal sequestration from wastewater by metal-organic frameworks: a state-of-the-art review of recent progress.

Metal-organic frameworks (MOFs) have emerged as highly promising adsorbents for removing heavy metals from wastewater due to their tunable structures, high surface areas, and exceptional adsorption capacities. This review meticulously examines and summarizes recent advancements in producing and utilizing MOF-based adsorbents for sequestering heavy metal ions from water. It begins by outlining and contrasting commonly employed methods for synthesizing MOFs, such as solvothermal, microwave, electrochemical, ultrasonic, and mechanochemical. Rather than delving into the specifics of adsorption process parameters, the focus shifts to analyzing the adsorption capabilities and underlying mechanisms against critical metal(loid) ions like chromium, arsenic, lead, cadmium, and mercury under various environmental conditions. Additionally, this article discusses strategies to optimize MOF performance, scale-up production, and address environmental implications. The comprehensive review aims to enhance the understanding of MOF-based adsorption for heavy metal remediation and stimulate further research in this critical field. In brief, this review article presents a comprehensive overview of the contemporary information on MOFs as an effective adsorbent and the challenges being faced by these adsorbents for heavy metal mitigation (including stability, cost, environmental issues, and optimization), targeting to develop a vital reference for future MOF research.

Accelerating the practical application of MOFs for hydrogen storage—from performance-driven to application-oriented

Metal–organic frameworks (MOFs) are highly promising porous materials known for their exceptional porosity, extensive surface area, and customizable pore structures, making them an ideal solution for hydrogen storage. However, most MOFs research remains confined to the laboratory, lacking practical applications. To address this, the author proposes a shift towards practical applications, the creation of a comprehensive MOFs database, alignment of synthesis with practical considerations, and diversification of MOFs applications. These steps are crucial for harnessing the full potential of MOFs in real-world energy challenges.

Evaluation of Open-Source Large Language Models for Metal-Organic Frameworks Research.

Along with the development of machine learning, deep learning, and large language models (LLMs) such as GPT-4 (GPT: Generative Pre-Trained Transformer), artificial intelligence (AI) tools have been playing an increasingly important role in chemical and material research to facilitate the material screening and design. Despite the exciting progress of GPT-4 based AI research assistance, open-source LLMs have not gained much attention from the scientific community. This work primarily focused on metal-organic frameworks (MOFs) as a subdomain of chemistry and evaluated six top-rated open-source LLMs with a comprehensive set of tasks including MOFs knowledge, basic chemistry knowledge, in-depth chemistry knowledge, knowledge extraction, database reading, predicting material property, experiment design, computational scripts generation, guiding experiment, data analysis, and paper polishing, which covers the basic units of MOFs research. In general, these LLMs were capable of most of the tasks. Especially, Llama2-7B and ChatGLM2-6B were found to perform particularly well with moderate computational resources. Additionally, the performance of different parameter versions of the same model was compared, which revealed the superior performance of higher parameter versions.

Focused ion beam milling and MicroED structure determination of metal-organic framework crystals

We report new advancements in the determination and high-resolution structural analysis of beam-sensitive metal organic frameworks (MOFs) using microcrystal electron diffraction (MicroED) coupled with focused ion beam milling at cryogenic temperatures (cryo-FIB). A microcrystal of the beam-sensitive MOF, ZIF-8, was ion-beam milled in a thin lamella approximately 150 nm thick. MicroED data were collected from this thin lamella using an energy filter and a direct electron detector operating in counting mode. Using this approach, we achieved a greatly improved resolution of 0.59 Å with a minimal total exposure of only 0.64 e−/A2. These innovations not only improve model statistics but also further demonstrate that ion-beam milling is compatible with beam-sensitive materials, augmenting the capabilities of electron diffraction in MOF research.

Exploring the Structural, Dynamic, and Functional Properties of Metal‐Organic Frameworks through Molecular Modeling

AbstractThis review spotlights the role of atomic‐level modeling in research on metal‐organic frameworks (MOFs), especially the key methodologies of density functional theory (DFT), Monte Carlo (MC) simulations, and molecular dynamics (MD) simulations. The discussion focuses on how periodic and cluster‐based DFT calculations can provide novel insights into MOF properties, with a focus on predicting structural transformations, understanding thermodynamic properties and catalysis, and providing information or properties that are fed into classical simulations such as force field parameters or partial charges. Classical simulation methods, highlighting force field selection, databases of MOFs for high‐throughput screening, and the synergistic nature of MC and MD simulations, are described. By predicting equilibrium thermodynamic and dynamic properties, these methods offer a wide perspective on MOF behavior and mechanisms. Additionally, the incorporation of machine learning (ML) techniques into quantum and classical simulations is discussed. These methods can enhance accuracy, expedite simulation setup, reduce computational costs, as well as predict key parameters, optimize geometries, and estimate MOF stability. By charting the growth and promise of computational research in the MOF field, the aim is to provide insights and recommendations to facilitate the incorporation of computational modeling more broadly into MOF research.

Alignment of Breathing Metal-Organic Framework Particles for Enhanced Water-Driven Actuation.

As the majority of known metal-organic frameworks (MOFs) possess anisotropic crystal lattices and thus anisotropic physicochemical properties, a pressing practical challenge in MOF research is the establishment of robust and simple processing methods to fully harness the anisotropic properties of the MOFs in various applications. We address this challenge by applying an E-field to precisely align MIL-88A microcrystals and generate MIL-88A@polymer films. Thereafter, we demonstrate the impact of MOF crystal alignment on the actuation properties of the films as a proof of concept. We investigate how different anisotropies of the MIL-88A@polymer films, specifically, crystal anisotropy, particle alignment, and film composition, can lead to the synergetic enhancement of the film actuation upon water exposure. Moreover, we explore how the directionality in application of the external stimuli (dry/humid air stream, water/air interface) affects the direction and the extent of the MIL-88A@polymer film movement. Apart from the superior water-driven actuation properties of the developed films, we demonstrate by dynamometer measurements the higher degree of mechanical work performed by the aligned MIL-88A@polymer films with the preserved anisotropies compared to the unaligned films. The insights provided by this work into anisotropic properties displayed by aligned MIL-88A@polymer films promise to translate crystal performance benefits measured in laboratories into real-world applications. We anticipate that our work is a starting point to utilize the full potential of anisotropic properties of MOFs.

Constructing Physiological Defense Systems against Infectious Disease with Metal-Organic Frameworks: A Review.

The swift and deadly spread of infectious diseases, alongside the rapid advancement of scientific technology in the past several centuries, has led to the invention of various methods for protecting people from infection. In recent years, a class of crystalline porous materials, metal-organic frameworks (MOFs), has shown great potential in constructing defense systems against infectious diseases. This review addresses current approaches to combating infectious diseases through the utilization of MOFs in vaccine development, antiviral and antibacterial treatment, and personal protective equipment (PPE). Along with an updated account of MOFs used for designing defense systems against infectious diseases, directions are also suggested for expanding avenues of current MOF research to develop more effective approaches and tools to prevent the widespread nature of infectious diseases.

Applications of MOFs in Drug Delivery

The main research focus of this article is the application of Metal-Organic Frameworks (MOFs) in drug delivery applications. The review primarily concentrates on the methods used for loading drugs into MOFs, their response to stimuli, potential applications, and limitations. The article begins with discussing the limitations of traditional drug delivery systems and introduces MOFs as a potential solution to these limitations. The drug loading strategy section describes the three main methods for loading drugs into MOFs, including their respective benefits and drawbacks. The stimulus response release program section explores various stimuli that can trigger drug release from MOFs, including physical, chemical, and biological factors, and provides examples of how MOFs can respond to these stimuli. The section on application and challenges provides an overview of current studies exploring the potential of MOFs in biomedical applications, including cancer therapy, antibacterial therapy, and anti-inflammatory therapy, while also highlighting the key challenges facing MOFs research, such as biocompatibility and toxicity. Finally, the article concludes by offering prospects for future developments in MOFs research. This review article provides a significant resource for drug delivery researchers and practitioners who wish to investigating the possibility of utilizing MOFs as novel drug delivery vehicles.

The Upcoming Future of Metal-Organic Frameworks: Challenges and Opportunities

Metal–organic frameworks (MOFs) belong to the group of porous and crystalline substances that enable the diversity of composition and structure beyond conventional solid-state materials. In the past few years’ MOFs have created enormous interest due to their potential applications in clean energy, becoming a storage medium for H2 and CH4. The luminescent metal-organic frameworks (LMOFs) are recognized for a broad range of applications in chemical sensing, energy-efficient lighting, removal of toxic substances from gases and liquids, bio-imaging, and related fields. The present review highlights the basic methods of synthesis, current challenges in the synthesis of novel MOF materials, various characterization methods, scope, and opportunities available for the future related to MOF research. The application of MOF materials in packaging and catalysis was also discussed.Keywords: Luminescent, Metal–organic frameworks (MOFs), Sensors, Storage energies, Supercapacitors.

Experimental Approaches for the Synthesis of Low-Valent Metal-Organic Frameworks from Multitopic Phosphine Linkers.

Metal-organic frameworks (MOFs) are the subject of intense research focus due to their potential applications in gas storage and separation, biomedicine, energy, and catalysis. Recently, low-valent MOFs (LVMOFs) have been explored for their potential use as heterogeneous catalysts, and multitopic phosphine linkers have been shown to be a useful building block for the formation of LVMOFs. However, the synthesis of LVMOFs using phosphine linkers requires conditions that are distinct from those in the majority of the MOF synthetic literature, including the exclusion of air and water and the use of unconventional modulators and solvents, making it somewhat more challenging to access these materials. This work serves as a general tutorial for the synthesis of LVMOFs with phosphine linkers, including information on the following: 1) the judicious choice of the metal precursor, modulator, and solvent; 2) the experimental procedures, air-free techniques, and required equipment; 3) the proper storage and handling of the resultant LVMOFs; and 4) useful characterization methods for these materials. The intention of this report is to lower the barrier to this new subfield of MOF research and facilitate advancements toward novel catalytic materials.

Review on Metal-Organic Framework Classification, Synthetic Approaches, and Influencing Factors: Applications in Energy, Drug Delivery, and Wastewater Treatment.

Metal ions or clusters that have been bonded with organic linkers to create one- or more-dimensional structures are referred to as metal-organic frameworks (MOFs). Reticular synthesis also forms MOFs with properly designated components that can result in crystals with high porosities and great chemical and thermal stability. Due to the wider surface area, huge pore size, crystalline nature, and tunability, numerous MOFs have been shown to be potential candidates in various fields like gas storage and delivery, energy storage, catalysis, and chemical/biosensing. This study provides a quick overview of the current MOF synthesis techniques in order to familiarize newcomers in the chemical sciences field with the fast-growing MOF research. Beginning with the classification and nomenclature of MOFs, synthesis approaches of MOFs have been demonstrated. We also emphasize the potential applications of MOFs in numerous fields such as gas storage, drug delivery, rechargeable batteries, supercapacitors, and separation membranes. Lastly, the future scope is discussed along with prospective opportunities for the synthesis and application of nano-MOFs, which will help promote their uses in multidisciplinary research.

Metal‐organic framework derived porous structures towards lithium rechargeable batteries

AbstractBatteries are a promising technology in the field of electrical energy storage and have made tremendous strides in recent few decades. In particular, lithium‐ion batteries are leading the smart device era as an essential component of portable electronic devices. From the materials aspect, new and creative solutions are required to resolve the current technical issues on advanced lithium (Li) batteries and improve their safety. Metal‐organic frameworks (MOFs) are considered as tempting candidates to satisfy the requirements of advanced energy storage technologies. In this review, we discuss the characteristics of MOFs for application in different types of Li batteries. A review of these emerging studies in which MOFs have been applied in lithium storage devices can provide an informative blueprint for future MOF research on next‐generation advanced energy storage devices.image

Bio-metal-organic framework-based cobalt glutamate for CO2/N2 separation: Experimental and multi-objective optimization with a neural network

The outstanding properties of metal-organic frameworks (MOFs) have proven that this type of crystalline adsorbent has great potential in CO2 capture applications. Most of the MOF research studies on new functional MOFs are conducted to improve the performance of CO2 gas adsorption. Combined studies of material evaluation and process design on engineering issues in CO2 capture applications in industry are rarely carried out. In this study, the authors attempted to address engineering issues by developing a biometal-organic framework with the bioligand L-glutamic acid that has more practical fabrication cost than petrochemical MOFs. Herein, the demonstration of the prediction and optimization of CO2 adsorption capacity, selectivity, and heat of adsorption using a multiobjective genetic algorithm (MOGA) combined with an artificial neural network (ANN). The success of the Bio-MOF fabrication was evaluated by scanning electron microscopy, N2 adsorption-desorption isotherm analysis, thermal gravimetric analysis, X-ray diffraction, and Fourier transform infrared spectroscopy techniques. Furthermore, volumetric measurements were performed at several temperatures (27, 35 and, 50 °C). The isosteric heat of adsorption was then evaluated by an indirect method with the Clausius-Clapeyron (C-C) and Chakraborty, Saha, and Koyama (CSK) equations. Then, CO2/N2 selectivity was analysed by IAST techniques by regressing the experimental data with the Langmuir-Freundlich isothermal equation. The computational study by ANN and MOGA also gives satisfying results in balancing three requirements criteria. Thus, this study paved the way for the development of low-cost scalable MOF fabrication in industry by applying the optimization and balancing principles of the three objective functions.

Metal‐Organic Frameworks: Synthesis, Structures, and Applications

Metal‐Organic Frameworks: Synthesis, Structures, and Applications

Seed-aided green synthesis of metal-organic frameworks in water

Green synthesis of metal-organic frameworks (MOFs) in water with alleviated environmental influence and reduced cost is an essential step to transfer laboratory MOFs research to industrial application. Switching from the commonly used organic solvents to pure water encounters challenges of the poor solubility of organic linkers, slow reaction kinetics, and the formation of polymorphic products. So far, a universal MOFs synthetic strategy in water system has yet to be developed. This study reports the seed-aided synthesis of eleven MOFs with diverse compositions and structures while pure water serving as solvent. The corresponding reaction temperature and time of using this new strategy were reduced compared with original synthetic approaches, while the products maintain porous structure and high crystallinity. The success of this strategy relies on the addition of parent MOFs as seeds which could promote crystallization process by skipping the time-consuming induction period and avoiding the formation of polymorphic impurities.

Structural Investigation into Magnesium Based MOFs Derived from Aliphatic Linkers

Lightweight metal–organic frameworks (MOFs) with large volume storage capabilities are highly sought after as solid adsorbents in gas storage applications. This is particularly important for hydrogen gas adsorbents and can be explored through constructing MOFs from magnesium, which is a light metal and can readily form lightweight frameworks. Recently, the use of bulky, 3D aliphatic linkers in MOF synthesis has resulted in materials with higher gas adsorption enthalpies at lower pressures. Here, we employ both aliphatic linkers and magnesium clusters to produce lightweight, aliphatic frameworks with potential use for gas adsorption applications. Two magnesium MOFs were synthesised, 3DL-MOF-2 and 3DL-MOF-3 (3DL = 3DLinker), and structurally investigated using single crystal X-ray diffraction. While these MOFs do not have any accessible void spaces and therefore cannot be used for gas adsorption, they create a platform for future magnesium aliphatic MOF research to form open frameworks.

The Current Status of MOF and COF Applications.

The amalgamation of different disciplines is at the heart of reticular chemistry and has broadened the boundaries of chemistry by opening up an infinite space of chemical composition, structure, and material properties. Reticular design has enabled the precise prediction of crystalline framework structures, tunability of chemical composition, incorporation of various functionalities onto the framework backbone, and as a consequence, fine-tuning of metal-organic framework (MOF) and covalent organic framework (COF) properties beyond that of any other material class. Leveraging the unique properties of reticular materials has resulted in significant advances from both a fundamental and an applied perspective. Here, we wish to review the milestones in MOF and COF research and give a critical view on progress in their real-world applications. Finally, we briefly discuss the major challenges in the field that need to be addressed to pave the way for industrial applications.

Preparation of UiO-66-NH2@PDA under Water System for Chemical Warfare Agents Degradation.

There is an urgent need to develop catalytic degradation technologies for chemical warfare agents (CWAs) that are environmentally friendly and do not require secondary treatment. UiO-66-NH2 and other metal–organic frameworks (MOFs) based on zirconium have been shown to promote the catalytic degradation of CWAs. At the same time, MOFs have been studied, and they have shown interesting properties in CWA removal because of their ultrahigh surface area, tunable structures, and periodically distributed abundant catalytic sites. However, MOFs synthesized by conventional methods are mostly powdery crystals that are difficult to process and have poor mechanical stability, which largely limit the development of MOFs in practical applications. An emerging trend in MOF research is hybridization with flexible materials. Polymers possess a variety of unique attributes, such as flexibility, thermal and chemical stability, and process ability, and these properties can be combined with MOFs to make a low-cost and versatile material that also provides convenience for the subsequent integration of such MOFs into independent substrates or textiles. In this article, we used a green and simple method to coat the surface of UiO-66-NH2 with polydopamine (PDA), PDA can promote the catalytic hydrolysis of UiO-66-NH2 to DMNP (a simulant of chemical warfare agents). Additionally, it can adsorb the toxic hydrolysis product p-nitrophenol, avoiding the trouble of secondary treatment. The half-life of UiO-66-NH2 coated with polydopamine (UiO-66-NH2@PDA) for catalytic hydrolysis is 8.9 min, and that of pure UiO-66-NH2 is 20 min. We speculate that the surface coated with PDA can improve the diffusion of DMNP to the active sites of UiO-66-NH2.

Structural Transformation and Spatial Defect Formation of a Co(II) MOF Triggered by Varied Metal-Center Coordination Configuration.

In spite of the attractive potential application of the dynamic behavior and defect of metal-organic framework (MOF), the achievement of these features is a challenging goal in the MOF research field. Herein, we report a Co(II) MOF, namely, [Co3(L)2(4-PTZ)2(H2O)2]n·solvent (H2L = 5-(isonicotinamido)isophthalic acid, 4-PTZ = 5-(4-pyridyl)-1H-tetrazole), that features dynamic structural transformation behaviors. By varying the coordination configuration of metal center through the removal of coordinated water molecules, the porous compound could undergo structural transformation to give a new crystalline phase with larger pore dimension. Moreover, the new phase features a mesoporous structure originating from the spatial defect that formed with the transformation process, which indicates that the modulation of dynamic behavior of the MOF could be a potential method for the engineering of a spatial defect. In addition, the gas sorption investigation results reveal that the new phase has enhanced selectivity for CO2/N2, CO2/CH4, and C2H2/C2H4 systems compared with that of the pristine phase, suggesting the potential of spatial defect engineering for the tuning of MOF gas sorption properties.

Ab Initio Prediction of Metal-Organic Framework Structures

Metal-organic frameworks (MOFs) have emerged as highly versatile materials with applications in gas storage and separation, solar light energy harvesting and photocatalysis. The design of new MOFs, however, has been hampered by the lack of computational methods for ab initio MOF structure prediction, which could be used to inspire and direct experimental synthesis. Here, we report the first ab initio method for the prediction of MOF structures and test it against a diverse set of known MOFs that were chosen for their differences in topology, metal coordination geometry, and ligand binding sites. In all cases, our calculations produced structures that match experiment using only the target composition and ligand molecular structure, proving the versatility of our procedure. The herein presented methodology utilizes the point group symmetry of ligands to enable, for the first time, prediction of MOF structures from first principles, without having to resort to empirical guidelines based on rigid connectivity of nodes and linkers, or to previously determined crystal structures and topologies of known MOFs. This advance provides the first tool to change MOF design from an empirically based process that is based on chemistʼs intuition rooted in literature- or database-established knowledge of node-and-linker connectivity to a more general and theory-driven materials development. This ab initio MOF structure prediction approach, which is here validated on a range of known MOF classes, provides a unique opportunity to explore the phase landscape of MOFs computationally and enables MOF research and development even in case of limited access to laboratory resources, as for example in case of a global pandemic.