Influence of Pressure and Temperature on the Flexible Behavior of Iron-Based MIL-53 with the CO2 Host: A Comprehensive Experimental and DFT Study

This research focuses on developing MIL-53-type compounds with Fe obtained with ligands derived from PET waste, followed by the controlled addition of hydrofluoric acid (HF). Incorporating HF into the MOF structure induced substantial changes in the material textural properties, resulting in a significant change in CO2 adsorption. Furthermore, a distinctive structural alteration (breathing effect) was observed in the CO2 isotherms at different temperatures; these structural changes have not been observed by X-ray diffraction (XRD) because this characterization has been performed at room temperature, whereas the adsorption experiments were conducted at 260, 273, and 303 K and different pressures. Subsequently, DFT studies were performed to investigate the CO2-filling mechanisms and elucidate the material respiration effect. This approach offers promising opportunities for sustainable materials with improved gas adsorption properties.

Porous crystalline materials for memories and neuromorphic computing systems

Porous crystalline materials usually include metal-organic frameworks (MOFs), covalent organic frameworks (COFs), hydrogen-bonded organic frameworks (HOFs) and zeolites, which exhibit exceptional porosity and structural/composition designability, promoting the increasing attention in memory and neuromorphic computing systems in the last decade. From both the perspective of materials and devices, it is crucial to provide a comprehensive and timely summary of the applications of porous crystalline materials in memory and neuromorphic computing systems to guide future research endeavors. Moreover, the utilization of porous crystalline materials in electronics necessitates a shift from powder synthesis to high-quality film preparation to ensure high device performance. This review highlights the strategies for preparing porous crystalline materials films and discusses their advancements in memory and neuromorphic electronics. It also provides a detailed comparative analysis and presents the existing challenges and future research directions, which can attract the experts from various fields (e.g., materials scientists, chemists, and engineers) with the aim of promoting the applications of porous crystalline materials in memory and neuromorphic computing systems.

Highly Efficient Propyne/Propylene Separation in a "Flexible-Robust" and Hydrolytically Stable Cu(II)-MOF

Propyne/propylene separation is important in the petrochemical industry but challenging due to their similar physical properties and close molecular sizes. Metal-organic frameworks (MOFs) are a class of promising adsorbents for light hydrocarbon separations. Among them, the so-called "flexible-robust" MOFs combine the advantages of flexibility and rigidity in structure and could show enhanced gas separation selectivity as well as improved gas uptake at low pressure. Interpenetrated MOFs offer a platform to explore the "flexible-robust" feature of MOFs based on their subnetwork displacement in the process of gas adsorption. Herein, we present two hydrolytically stable MOFs (BUT-308 and BUT-309) with interpenetrated structures and fascinating propyne/propylene separation performance. BUT-308 is composed of interpenetrated 2D Cu(BDC-NH₂)BPB layers (H₂BDC-NH₂ = 2-aminobenzene-1,4-dicarboxylic acid; BPB = 1,4-bis(4-pyridyl)benzene), while BUT-309 consists of twofold interpenetrated 3D pillared-layer Cu₂(BDC-NH₂)₂(BPB-CF₃) nets (BPB-CF₃ = 2-trifluoromethyl-1,4-bis(4-pyridyl)benzene). Gas adsorption measurements showed that BUT-309 was a "flexible-robust" adsorbent with multistep adsorption isotherms for C₃H₄ rather than C₃H₆ at a wide temperature range. The guest-dependent pore-opening behavior endows BUT-309 with high potential in the C₃H₄/C₃H₆ separation. The C₃H₄ adsorption measurements of BUT-309 at 273-323 K showed that the lowering of the temperature induced the pore-opening action at lower pressure. Column breakthrough experiments further confirmed the capability of BUT-309 for the efficient removal of C₃H₄ from a C₃H₄/C₃H₆ binary gas, and the C₃H₆ processing capacity at 273 K (15.7 cm³ g^-1) was higher than that at 298 K (35.2 cm³ g^-1). This work shows a rare example of "flexible-robust" MOFs and demonstrated its high potential for C₃H₄/C₃H₆ separation.

Properties of Aliphatic Ligand-Based Metal-Organic Frameworks

Ligands with a purely aliphatic backbone are receiving rising attention in the chemistry of coordination polymers and metal-organic frameworks. Such unique features inherent to the aliphatic bridges as increased conformational freedom, non-polarizable core, and low light absorption provide rare and valuable properties for their derived MOFs. Applications of such compounds in stimuli-responsive materials, gas, and vapor adsorbents with high and unusual selectivity, light-emitting, and optical materials have extensively emerged in recent years. These properties, as well as other specific features of aliphatic-based metal-organic frameworks are summarized and analyzed in this short critical review. Advanced characterization techniques, which have been applied in the reported works to obtain important data on the crystal and molecular structures, dynamics, and functionalities, are also reviewed within a general discussion. In total, 132 references are included.

Recent advances in Metal-Organic Frameworks as nanocarriers for triggered release of anticancer drugs: Brief history, biomedical applications, challenges and future perspective

Metal-Organic Frameworks (MOFs) have emerged as a promising biomedical material due to its unique features such as high surface area, pore volume, variable pore size, flexible functional groups, and excellent efficiency for drug loading. In this review, we explored the use of novel and smart metal organic frameworks as drug delivery vehicles to discover a safer and more controlled mode of drug release aiming to minimize their side effects. Here, we systematically discussed the background of MOFs following a thorough review on structural and physical properties of MOFs, their synthesis techniques, and the important characteristics to establish a strong foundation for future research. Furthermore, the current status on the potential applications of MOF-based stimuli-responsive drug delivery systems, including pH-, ion-, temperature-, light-, and multiple responsive systems for the delivery of anticancer drugs has also been presented. Lastly, we discuss the prospects and challenges in implementation of MOF-based materials in the drug delivery. Therefore, this review will help researchers working in the relevant fields to enhance their understanding of MOFs for encapsulation of various drugs as well as their stimuli responsive mechanism.

Particle size-dependent flexibility in DUT-8(Cu) pillared layer metal-organic framework

The nature of metal in the isomorphous flexible metal-organic frameworks is often reported to influence flexibility and responsivity. A prominent example of such behaviour is the DUT-8(M) family ([M₂(2,6-ndc)₂(dabco)]_n, 2,6-ndc = 2,6-naphthalene dicarboxylate, dabco = 1,4-diazabicyclo-[2.2.2]-octane), where the isostructural compounds with Ni, Zn, Co, and Cu in the paddle wheel cluster are known. The macro-sized crystals of Ni, Co, and Zn based compounds transform to the closed pore (cp) phase under desolvation and show typical gate opening behaviour upon adsorption. The choice of metal, in this case, allows the adjustment of switching kinetics, selectivity in adsorption, and gate-opening pressures. The submicron-sized crystals of of Ni, Co, and Zn based compounds remain in the open pore (op) phase after desolvation. In this contribution, we demonstrate that the presence of Cu in the paddle wheel leads to fundamentally different flexible behaviour. The DUT-8(Cu) desolvation does not lead to the formation of the cp phase, independent of the particle size regime. However, according to in situ powder diffraction analysis, the desolvated, macro-sized crystals of DUT-8(Cu)_op show breathing upon adsorption of CO₂ at 195 K. The submicron-sized particles show rigid, nonresponsive behaviour.

Metal-ligand Lability and Ligand Mobility Enables Framework Transformation via Ligand Release in a Family of Crystalline 2D Coordination Polymers

A family of seven silver(I)-perfluorocarboxylate-quinoxaline coordination polymers, [Ag4 (O2 CRF )4 (quin)4 ] 1-5 (RF =(CF2 )n-1 CF3 )4 , n=1 to 5); [Ag4 (O2 C(CF2 )2 CO2 )2 (quin)4 ] 6; [Ag4 (O2 CC6 F5 )4 (quin)4 ] 7 (quin=quinoxaline), denoted by composition as 4 : 4 : 4 phases, was synthesised from reaction of the corresponding silver(I) perfluorocarboxylate with excess quinoxaline. Compounds 1-7 adopt a common 2D layered structure in which 1D silver-perfluorcarboxylate chains are crosslinked by ditopic quinoxaline ligands. Solid-state reaction upon heating, involving loss of one equivalent of quinoxaline, yielding new crystalline 4 : 4 : 3 phases [Ag4 (O2 C(CF2 )n-1 CF3 )4 (quin)3 ]n (8-10, n=1 to 3), was followed in situ by PXRD and TGA studies. Crystal structures were confirmed by direct syntheses and structure determination. The solid-state reaction converting 4 : 4 : 4 to 4 : 4 : 3 phase materials involves cleavage and formation of Ag-N and Ag-O bonds to enable the structural rearrangement. One of the 4 : 4 : 3 phase coordination polymers (10) shows the remarkably high dielectric constant in the low electric field frequency range.

Efficient biodiesel production from oleic and palmitic acid using a novel molybdenum metal-organic framework as efficient and reusable catalyst

In this study, metal-organic framework based on molybdenum and piperidine-4-carboxylic acid, was synthesized through a simple solvothermal method and employed as an effective catalyst for biodiesel production from oleic acid and palmitic acid via esterification reaction. The prepared catalyst was characterized by XRD, FTIR, TGA, DSC, BET, SEM, TEM, ICP-OES, X-ray mapping and EDX analysis. The resulting Mo-MOF catalyst exhibit a rod-like morphology, specific surface area of 56 m2/g, and thermal stability up to 300 °C. The solid catalyst exhibited high activities for esterification of oleic acid and palmitic acid. Moreover, the catalyst could be simply recovered and efficiently reutilized for several times without significant loss in its activity, also obtained results revealed that metal-organic framework could be used for the appropriate and rapid biodiesel production.