Microwave-assisted activation and modulator removal in zirconium MOFs for buffer-free CWA hydrolysis

Valorizing natural-abundant glucose to lactic acid using a MOF-808 catalyst under green hydrothermal conditions

Highly robust Zr-based MOF-808, featuring Lewis acid Zr sites and coordinate hydroxide ions upon the removal of the monocarboxylate capping reagent, emerges as an efficient catalyst for the hydrothermal conversion of glucose into lactic acid. A remarkable 99% glucose conversion with an impressive 76.6% yield of lactic acid can be achieved. The large pore window of MOF-808 facilitates the diffusion of glucose to the active sites within the framework. The single-site attribute of the catalytic center enables a high selectivity of lactic acid over the competitive product, 5-(hydroxymethyl)furfural, under hydrothermal reaction conditions.

Facile Recycling Strategy of Dyed Polyester Waste by Template-Based Synthesis of UiO-66 for Value-Added Transformation into Self-detoxifying Fabrics

Polyethylene terephthalate (PET) accounts for a significant portion of textile waste, and recycling strategies for this material have attracted much attention. This study proposes a facile and innovative PET recycling method applicable to environmental remediation that involves the conversion of dyed PET fabric waste into a value-added fabric. Herein, a template-based synthesis approach capable of growing a UiO-66 metal-organic framework (MOF) directly on a dyed PET fabric is reported. The advantage of this process lies in its simplicity, where the partial hydrolysis of PET followed by a zirconium chloride treatment results in the successful growth of UiO-66 on a dyed PET fabric with the concurrent removal of the dye without additional steps. The catalytic performance of the UiO-66-grown fabric was evaluated through the degradation of dimethyl 4-nitrophenyl phosphate (DMNP), a nerve agent simulant. The fabric produced by the simple metal treatment (Zr@PEThyd) exhibited excellent DMNP degradation performance with t1/2 = 43.3 min and maintained functional stability after a harsh washing procedure, an outcome attributed to the surface-assisted UiO-66 growth that ensured good bonding stability. The developed process is innovative in that it uses dyed PET waste as a template for the direct growth of UiO-66, simplifying the process without compromising the catalytic functionality. This research provides an informative option for a sustainable textile recycling strategy by transforming dyed PET waste into an advanced self-detoxifying material.

Greatly Intensified Guest Exchange Strategy for Highly-Efficient Activation of Metal-Organic Frameworks

The preservation and accessibility of pores are prerequisites to the application of metal-organic frameworks (MOFs). Activation is a key step to eliciting rich features of pores, but it needs a repeated solvent-exchange process which is tedious and time/cost-consuming. Herein, a facile strategy for highly-efficient activation of MOFs utilizing rotating packed bed is proposed. With the tremendous enhancement of molecular mixing and mass transfer in high-gravity and strong-shearing surrounding, nine representative MOFs are completely activated within 2 h without structural change. Compared with conventional process, this activation displays surprising efficiency by accelerating the diffusion of solvents and redissolution of residual reactants in the pores. The complete activation time can be significantly shortened by over 90%. As a proof-of-concept, the methane storage of as-activated UiO-66 is five times that of as-synthesized UiO-66. This strategy provides a potential platform with industrial worth for the activation of MOF materials with ultra-high efficiency and versatility.

Ligand regulated metal–organic frameworks for synergistic photoredox and nickel catalysis

Synergistic photoredox and nickel catalytic cross-coupling systems have created a great attraction as a promising methodology to produce the aryl C−N bonds under mild conditions as well as extreme challenge,...

Facile Synthesis of Metal-Organic Layers with High Catalytic Performance toward Detoxification of a Chemical Warfare Agent Simulant

Two-dimensional (2D) metal-organic layer (MOL) materials are highly desired against chemical warfare agents (CWAs). However, the rapid synthesis of 2DMOLs with open metal sites in a single step is very challenging. Herein, a facile bottom-up method for synthesizing MOLs with microwave assistance is applied to produce Zr/Hf-BTB MOLs, composed of six-connected M₆O₄(OH)₄¹²⁺ and the tritopic carboxylate ligand 1,3,5-tris(4-carboxyphenyl)benzene (BTB). The synthesis and ligand exchange steps can be combined into a single step to yield MOLs with active open sites directly. The as-synthesized MOLs demonstrate excellent catalytic performance toward the degradation of a CWA simulant. The theoretical calculations confirm that the high catalytic activity is due to the formate groups coordinated to the metal nodes being replaced by hydroxyl groups. The present work not only develops a method for the fast synthesis of 2D MOLs with active open metal sites in a single step but also provides a first demonstration for the application of 2D metal coordination materials in CWA protection.

Advances in applied supramolecular technologies

Supramolecular chemistry has successfully built a foundation of fundamental understanding. However, with this now achieved, we show how this area of chemistry is moving out of the laboratory towards successful commercialisation.

Modulated self-assembly of metal-organic frameworks

Exercising fine control over the synthesis of metal-organic frameworks (MOFs) is key to ensuring reproducibility of physical properties such as crystallinity, particle size, morphology, porosity, defectivity, and surface chemistry. The principle of modulated self-assembly - incorporation of modulator molecules into synthetic mixtures - has emerged as the primary means to this end. This perspective article will detail the development of modulated synthesis, focusing primarily on coordination modulation, from a technique initially intended to cap the growth of MOF crystals to one that is now used regularly to enhance crystallinity, control particle size, induce defectivity and select specific phases. The various mechanistic driving forces will be discussed, as well as the influence of modulation on physical properties and how this can facilitate potential applications. Modulation is also increasingly being used to exert kinetic control over self-assembly; examples of phase selection and the development of new protocols to induce this will be provided. Finally, the application of modulated self-assembly to alternative materials will be discussed, and future perspectives on the area given.

Swell and Destroy: A Metal-Organic Framework-Containing Polymer Sponge That Immobilizes and Catalytically Degrades Nerve Agents

Organophosphorus chemical warfare agents function as potent neurotoxins. Whilst the destruction of nerve agents is most readily achieved by hydrolysis, their storage and transport are hazardous and lethal in milligram doses, with any spillage resulting in fatalities. Furthermore, current decontamination and remediation measures are limited by a need for stoichiometric reagents, solvents, and buffered solutions, complicating the process for the treatment of bulk contaminants. Herein, we report a composite polymer material capable of rendering bulk VX unusable by immobilization within a porous polymer until a metal-organic framework (MOF) catalyst fully hydrolyzes the neurotoxin. This is an all-in-one capability that minimizes the use of multiple reagents, facilitated by a porous high internal phase emulsion-based polystyrene monolith housing an active zirconia MOF catalyst (MOF-808); the porous polymer absorbs and immobilizes the liquid agents, while the MOF enables hydrolysis. The dichotomous hierarchy of porous materials facilitates the containment and rapid hydrolysis of VX (>80% degradation in 8 h) in the presence of excess H₂O. This composite can further enable the hydrolysis of neat VX with reliance on ambient humidity (>95% in 11 days). Potentially, 4.5 kg of the composite can absorb, immobilize, and degrade the contents of a standard chemical drum/barrel (208 L, 55 gal) of the chemical warfare agent (CWA). We believe that this composite is the first example of what will be the go-to approach for CWA immobilization and degradation in the future. Furthermore, we believe that this demonstration of a catalytically reusable absorbent sponge provides a signpost for the development of similar materials where immobilization of a substrate in a catalytically active environment is desirable.

A historical overview of the activation and porosity of metal–organic frameworks

A historical overview of the activation and porosity of MOFs including strategies to design and preserve permanent porosity in MOFs.

Exploiting Microwave Chemistry for Activation of Metal-Organic Frameworks

Microwave is thought of as a useful electromagnetic radiation tool because it is often used in real life as well as in a variety of chemical processes. Meanwhile, activation of metal-organic frameworks (MOFs), which must be essentially done to remove coordinating and pore-filling solvents before the use of MOFs for various applications, has been performed commonly with the methods of heat supply or solvent exchange. Here, we show a new methodological microwave activation (MA), realizing it with various MOFs such as HKUST-1, UiO-66, and MOF-74s. For instance, microwave irradiation to the MOF samples for 4-35 min leads to the complete activation of the MOFs without structural damage. As described below, we further demonstrate that the solvent-assisted MA, which is the MA process performed after the solvent exchange, can substantially reduce the time for the activation by 4 min.

Nanomaterials with enzyme-like characteristics (nanozymes): next-generation artificial enzymes (II)

An updated comprehensive review to help researchers understand nanozymes better and in turn to advance the field.