Monolithic metal-organic frameworks for carbon dioxide separation

The structuring of porous reticular materials for energy applications at industrial scales

Reticular synthesis constructs crystalline architectures by linking molecular building blocks with robust bonds. This process gave rise to reticular chemistry and permanently porous solids. Such precise control over pore shape, size and surface chemistry makes reticular materials versatile for gas storage, separation, catalysis, sensing, and healthcare applications. Despite their potential, the transition from laboratory to industrial applications remains largely limited. Among various factors contributing to this translational gap, the challenges associated with their formulation through structuring and densification for industrial compatibility are significant yet underexplored areas. Here, we focus on the shaping strategies for porous reticular materials, particularly metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), to facilitate their industrial application. We explore techniques that preserve functionality and ensure durability under rigorous industrial conditions. The discussion highlights various configurations - granules, monoliths, pellets, thin films, gels, foams, and glasses - structured to maintain the materials' intrinsic microscopic properties at a macroscopic level. We examine the foundational theory and principles behind these shapes and structures, employing both in situ and post-synthetic methods. Through case studies, we demonstrate the performance of these materials in real-world settings, offering a structuring blueprint to inform the selection of techniques and shapes for diverse applications. Ultimately, we argue that advancing structuring strategies for porous reticular materials is key to closing the gap between laboratory research and industrial utilization.

Exploring porous structures without crystals: advancements with pair distribution function in metal- and covalent organic frameworks

The pair distribution function (PDF) is a versatile characterisation tool in materials science, capable of retrieving atom-atom distances on a continuous scale (from a few angstroms to nanometres), without being restricted to crystalline samples. Typically, total scattering experiments are performed using high-energy synchrotron X-rays, neutrons or electrons to achieve a high atomic resolution in a short time. Recently, PDF analysis provides a powerful approach to target current characterisation challenges in the field of metal- and covalent organic frameworks. By identifying molecular interactions on the pore surfaces, tracking complex structural transformations involving disorder states, and elucidating nucleation and growth mechanisms, structural analysis using PDF has provided invaluable insights into these materials. This review article highlights the significance of PDF analysis in advancing our understanding of MOFs and COFs, paving the way for innovative applications and discoveries in porous materials research.

Water sorption studies with mesoporous multivariate monoliths based on UiO-66

Hierarchical linker thermolysis has been used to enhance the porosity of monolithic UiO-66-based metal-organic frameworks (MOFs) containing 30 wt% 2-aminoterephthalic acid (BDC-NH2) linker. In this multivariate (i.e. mixed-linker) MOF, the thermolabile BDC-NH2 linker decomposed at ∼350 °C, inducing mesopore formation. The nitrogen sorption of these monolithic MOFs was probed, and an increase in gas uptake of more than 200 cm3 g-1 was observed after activation by heating, together with an increase in pore volume and mean pore width, indicating the creation of mesopores. Water sorption studies were conducted on these monoliths to explore their performance in that context. Before heating, monoUiO-66-NH2-30%-B showed maximum water vapour uptake of 61.0 wt%, which exceeded that reported for either parent monolith, while the highly mesoporous monolith (monoUiO-66-NH2-30%-A) had a lower maximum water vapour uptake of 36.2 wt%. This work extends the idea of hierarchical linker thermolysis, which has been applied to powder MOFs, to monolithic MOFs for the first time and supports the theory that it can enhance pore sizes in these materials. It also demonstrates the importance of hydrophilic functional groups (in this case, NH2) for improving water uptake in materials.

Noteworthy synthesis strategies and applications of metal-organic frameworks for the removal of emerging water pollutants from aqueous environment

17 global Sustainable Development Goals (SDGs) were established through the adoption of the 2030 Agenda for Sustainable Development by all United Nations members. Clean water and sanitation (SDG 6) and industry, innovation, and infrastructure (SDG 9) are the SDGs focus of this work. Of late, various new companies delivering metal-organic frameworks (MOFs) have blossomed and moved the field of adsorption utilizing MOFs to another stage. Inside this unique circumstance, this article aims to catch recent advancements in the field of MOFs and the utilizations of MOFs relate to the expulsion of arising contaminations that present huge difficulties to water quality because of their steadiness and possible damage to environments and human wellbeing. Customary water treatment techniques regularly neglect to eliminate these poisons, requiring the advancement of novel methodologies. This study overviews engineering techniques for controlling MOF characteristics for better flexibility, stability, and surface area. A current report on MOFs gathered new perspectives that are amicably discussed in emergent technologies and extreme applications towards environmental sectors. Various applications in many fields that exploit MOFs are being fostered, including gas storage, fluid separation, adsorbents, catalysis, medication delivery, and sensor utilizations. The surface area of a wide range of MOFs ranges from 103 to 104 m2/g, which exceeds the standard permeability of several material designs. MOFs with extremely durable porosity are more significant in their assortment and variety than other classes of porous materials. The work outlines the difficulties encountered in the synthesis steps and suggests ways to make use of MOFs' value in a variety of contexts. This caters to creating multivariate systems enclosed with numerous functionalities, leading to the synthesis of MOFs that offer a synergistic blend of in-built properties and exclusive applications. Additionally, the MOF-related future development opportunities and challenges are discussed.

Low temperature adsorption of CO2 in carbonaceous wedge pores: a Monte Carlo simulation study

A systematic study of carbon dioxide in wedge pores under subcritical conditions were conducted with Grand Canonical Monte Carlo simulation. The effects of various factors: temperature, pore geometry (i.e., pore width, length, tilt angle and corrugation), on the formation of stepwise isotherms, were particularly investigated. The occurrence of this step-wise adsorption behaviour is correlated to the alternate packing between the commensurate and incommensurate along the pore axis direction. The steps faded with temperature, due to the adsorbates are less structured and gradually receded mainly from the wide end where the weakest potential exerted to the fluids. The number of steps on desorption branch depends on the number of junctions and domains formed. The particles accumulating at the narrow end in open wedge pore play a role analogy to the closed end. Moreover, having corrugation on the interior solid surface also results different mechanisms illustrated in the stepwise behaviour due to the change in the actual pore size distribution and the interference to the force field inside the pore.

Metal-Organic Frameworks in Agriculture

Agrochemicals, which are crucial to meet the world food qualitative and quantitative demand, are compounds used to kill pests (insects, fungi, rodents, or unwanted plants). Regrettably, there are some important issues associated with their widespread and extensive use (e.g., contamination, bioaccumulation, and development of pest resistance); thus, a reduced and more controlled use of agrochemicals and thorough detection in food, water, soil, and fields are necessary. In this regard, the development of new functional materials for the efficient application, detection, and removal of agrochemicals is a priority. Metal-organic frameworks (MOFs) with exceptional sorptive, recognition capabilities, and catalytical properties have very recently shown their potential in agriculture. This Review emphasizes the recent advances in the use of MOFs in agriculture through three main views: environmental remediation, controlled agrochemical release, and detection of agrochemicals.