Reactive Polymers of Intrinsic Microporous Aerogels for Rapid Mustard Gas Detoxification

Polymers of intrinsic microporosity (PIMs) have broad application prospects in the detoxification of chemical warfare agents (CWAs) due to their unique pore structure, good tunable reactivity, and solution processability. However, its pore structure is relatively homogeneous, resulting in high resistance to mass transfer. Here, inspired by fractal structure in nature, a structure engineering strategy is proposed to develop 3D reactive nanofibrous aerogels featuring hierarchical porous structures to minimize mass transfer resistance. These aerogels are fabricated with amidoxime-modified PIM-1 (AO-PIM-1) nanofibers serving as building units and flexible SiO2 nanofibers acting as reinforcement. The macro/mesopores of amidoxime-modified PIM-1 nanofibrous aerogels (APAs) originating from freeze-shaping and electrospinning provide interconnected channels for the diffusion of CWAs, and the intrinsic micropores of AO-PIM-1 can effectively trap and anchor adsorbate molecules. In addition, the reactivity of the APAs can be activated by chlorine bleaching. This process forms an N-chlorine structure, which effectively oxidizes the adsorbed CWAs simulant 2-chloroethyl ethyl sulfide (CEES) by APAs, converting them into non-toxic products. The resulting aerogels have the properties of ultralight weight (8 mg cm-3), reversible compression strain of 60%, and repeatable sulfur mustard decontamination (half-life of 1.27 min). These characteristics indicate significant potential for the use in protective materials against vesicant CWAs.

Research Progress in the Degradation of Chemical Warfare Agent Simulants Using Metal-Organic Frameworks

Chemical warfare agents primarily comprise organophosphorus nerve agents, saliva alkaloids, cyanides, and mustard gas. Exposure to these agents can result in severe respiratory effects, including spasms, edema, and increased secretions leading to breathing difficulties and suffocation. Protecting public safety and national security from such threats has become an urgent priority. Porous metal-organic framework (MOF) materials have emerged as promising candidates for the degradation of chemical warfare agents due to their large surface area, tunable pore size distribution, and excellent catalytic performance. Furthermore, combining MOFs with polymers can enhance their elasticity and processability and improve their degradation performance. In this review, we summarize the literature of the past five years on MOF-based composite materials and their effectiveness in degrading chemical warfare agents. Moreover, we discuss key factors influencing their degradation efficiency, such as MOF structure, pore size, and functionalization strategies. Furthermore, we highlight recent developments in the design of MOF-polymer composites, which offer enhanced degradation performance and stability for practical applications in CWA degradation. These composite materials exhibit good performance in degrading chemical warfare agents, playing a crucial role in protecting public safety and maintaining national security. We can expect to see more breakthroughs in the application of metal-organic framework porous materials for degrading chemical warfare agents. It is hoped that these innovative materials will play a positive role in achieving social stability and security.

Sustainable Gold Nanoparticle (Au-NP) Growth within Interspaces of Porphyrinic Zirconium-Based Metal-Organic Frameworks: Green Synthesis of PCN-224/Au-NPs and Its Anticancer Effect on Colorectal Cancer Cells Assay

In this work, a simple green synthesis method of the novel metal-organic framework (MOF) nanocomposite PCN-224/Au-NPs (Au-NPs = gold nanoparticles) is described. In this regard, initially, PCN-224 was synthesized. Afterward, in a single-step, one-pot procedure, under visible-light irradiation, Au-NPs were fabricated on PCN-224. The cytotoxicity effect of the synthesized PCN-224/Au-NPs nanocomposite was investigated in human colon cancer cells. Determination of the apoptosis induction was done by the Annexin- V/propidium iodide flow cytometry method. Besides, to ascertain the biocompatibility of the synthesized sample, the cytotoxicity of PCN-224/Au-NPs was evaluated on the human embryonic kidney (HEK)-293 cell line. The substantial anticancer activity with the biocompatibility of the structure, the green facile synthesis, and the MOF surface of the synthesized nanocomposite make it special for utilization in therapeutic applications.

MOF-Integrated Hierarchical Composite Fiber for Efficient Daytime Radiative Cooling and Antibacterial Protective Textiles

Incorporating passive radiative cooling into textiles is an effective way to improve individual personalized thermophysiological comfort for the human body. Based on radiative cooling textile design, rational functionalization further facilitates practical applications, especially for medical protective products with customized requirements. Herein, we present a hierarchical polyurethane/metal-organic framework (MOF) composite nanofiber membrane with an integrated radiative cooling effect and photocatalytic antibacterial property. Fabricated by a scalable electrospinning method, the hierarchical nanofiber membrane shows high solar reflectance of 97% and improved thermal emissivity of 93% attributed to the abundant chemical bonds in ZIF-8 nanoparticles, rendering a temperature drop of ∼7.2 °C under direct sunlight and ∼5.5 °C at night. In addition, the photocatalytic activity of ZIF-8 ensures a 96% bacterial mortality rate for preventing bacterial infection. In practical application, our composite fabric can prevent superheating by 4.4 °C compared with the traditional protective suit under direct sunlight. Along with its anti-infection ability, the composite fabric is desirable for medical protective textiles. The innovative integration of passive radiative cooling design and functional MOFs breaks through the traditional cooling mode and provides huge substantial advantages for smart textiles and personal cooling applications.

Metal-organic framework-based materials for the abatement of air pollution and decontamination of wastewater

Developing new and efficient technologies for environmental remediation is becoming significant due to the increase in global concerns such as climate change, severe epidemics, and energy crises. Air pollution, primarily due to increased levels of H₂S, SO_x, NH₃, NO_x, CO, volatile organic compounds (VOC), and particulate matter (PM) in the atmosphere, has a significant impact on public health, and exhaust gases harm the natural sulfur, nitrogen, and carbon cycles. Similarly, wastewater discharged to the environment with metal ions, herbicides, pharmaceuticals, personal care products, dyes, and aromatics/organic compounds is a risk for health since it may lead to an outbreak of waterborne pathogens and increase the exposure to endocrine-disrupting agents. Therefore, developing new and efficient air and water quality management systems is critical. Metal-organic frameworks (MOFs) are novel materials for which the main application areas include gas storage and separation, water harvesting from the atmosphere, chemical sensing, power storage, drug delivery, and food preservation. Due to their versatile structural motifs that can be modified during synthesis, MOFs also have a great promise for green applications including air and water pollution remediation. The motivation to use MOFs for environmental applications prompted the modification of their structures via the addition of metal and functional groups, as well as the creation of heterostructures by mixing MOFs with other nanomaterials, to effectively remove hazardous contaminants from wastewater and the atmosphere. In this review, we focus on the state-of-the-art environmental applications of MOFs, particularly for water treatment and air pollution, by highlighting the groundbreaking studies in which MOFs have been used as adsorbents, membranes, and photocatalysts for the abatement of air and water pollution. We finally address the opportunities and challenges for the environmental applications of MOFs.

Metalloporphyrin Metal–Organic Frameworks: Eminent Synthetic Strategies and Recent Practical Exploitations

The emergence of metal–organic frameworks (MOFs) in recent years has stimulated the interest of scientists working in this area as one of the most applicable archetypes of three-dimensional structures that can be used as promising materials in several applications including but not limited to (photo-)catalysis, sensing, separation, adsorption, biological and electrochemical efficiencies and so on. Not only do MOFs have their own specific versatile structures, tunable cavities, and remarkably high surface areas, but they also present many alternative procedures to overcome emerging obstacles. Since the discovery of such highly effective materials, they have been employed for multiple uses; additionally, the efforts towards the synthesis of MOFs with specific properties based on planned (template) synthesis have led to the construction of several promising types of MOFs possessing large biological or bioinspired ligands. Specifically, metalloporphyrin-based MOFs have been created where the porphyrin moieties are either incorporated as struts within the framework to form porphyrinic MOFs or encapsulated inside the cavities to construct porphyrin@MOFs which can combine the peerless properties of porphyrins and porous MOFs simultaneously. In this context, the main aim of this review was to highlight their structure, characteristics, and some of their prominent present-day applications.

Novel "Turn-On" Luminescent Chemosensor for Arginine by Using a Lanthanide Metal-Organic Framework Photosensitizer

Arginine is considered as a biomarker of cystinuria and other diseases, and thus, it is of urgency to develop a simple and rapid method with high sensitivity and selectivity for arginine detection to meet the demand of on-site analysis and bedside diagnosis. In this work, a lanthanide metal-organic framework, La(TATB), was prepared using a triazine-based planar ligand, 4,4',4″-s-triazine-2,4,6-triyltribenzoate (H₃TATB), and lanthanide ion (La³⁺). La(TATB) can be used as a highly photosensitive agent to activate molecular oxygen to ¹O₂ to achieve efficient photosensitive oxidation of arginine accompanied by strong blue fluorescence emission under 302 nm UV irradiation. Due to the porous structure and high specific surface area of La(TATB), short-life ¹O₂ can effectively approach and react with amino acid substrate molecules, thus leading to higher sensitivity than other systems. Therefore, the "turn-on" fluorescence sensing of trace arginine can be realized, with a measured linear response range of 10-20,000 nM and a limit of detection as low as 7 nM. This method can be used for the detection of trace arginine in urine, which is conducive to the bedside diagnosis and rapid screening of cystinuria and other diseases. The proposed method not only expands the application scope of Ln-MOFs but also provides a new construction strategy for "turn-on" luminescence sensors.

Inclusive DFT insight into sensing mechanism of cyclotetrapyrole towards lung irritants

The development of smart sensing devices for toxic analytes detection especially lung irritants is much essential. The cyclic conducting polymers having infinite π-conjugation are proved to be highly sensitive for toxic analytes. Herein, by using the DFT approach, we investigated the sensing mechanism of cyclotetrapyrole (CTPy) for accurate detection of phosgene, diphosgene, chloropicrin and chlorine at the B3LYP-D3/6-31 + G (d, p) level. The calculated interaction energies show the physisorption of analytes over the CTPy surface. Natural bond orbital (NBO) and charge decomposition (CDA) analyses predict charge transfer interactions in the complexes. The reduced density gradient (RDG) approach reveals that hydrogen bonding interactions dominate in the complexes. The sensitivity of CTPy towards lung irritants is further illustrated by the reduction in HOMO-LUMO energy gaps, red shifting of [Formula: see text] in UV-Visible spectra. Density of state (DOS) analysis affirm that enhanced conductivity upon complexation is due to the origination of new energy states in occupied and virtual orbitals nearer to the Fermi level. Moreover, PDOS spectra show that CTPy primarily contributes to the energy of HOMO. The outcome of the current study depicts appreciable sensitivity of CTPy towards lung irritants. Moreover, the competing role of naturally occurring atmospheric water is also investigated. We believe that the upshot of the current findings and their forecasts will provide useful guidelines for an experimentalist to design highly sensitive sensors for toxic analytes using CTPy. HIGHLIGHTS: • The highest QNBO transfer towards the analyte (- 0.121) is seen in the chlorine@CTPy complex. • The highest reduction in Eg (61%) between occupied and virtual orbitals is noticed in chlorine@CTPy. • The orbital overlap results in a 41% red shifting of [Formula: see text] in chlorine@CTPy. • Cyclotetrapyrole is highly sensitive for chlorine.

Porphyrin-based MOFs as heterogeneous photocatalysts for the eradication of organic pollutants and toxins

Water and air pollution are among the major environmental challenges of this era. Waste management, economic sustainable development and renewable energy are unavoidable concomitant considerations. Over the past five years, nanosized metal-organic frameworks (nano-MOFs) have been developed for the elimination of pollutants in wet media and air-born toxins using the highly efficient reactive oxygen species (ROS) of type I (H2O2, •OH, O[Formula: see text] and of type II (1O[Formula: see text]. The ROS are catalytically and efficiently generated through photosensitization, and porphyrins and metalloporphyrins are pigments of choice for this purpose. This short review summarizes the fundamentals of ROS generation by porphyrin-based nano-MOFs (mainly through the formation of ROS type II) and their composites (leading to ROS type I), which includes energy and electron transfer processes, and their applications in these environmental issues.

Tuning the Conduction Band Potential of Bi-based Semiconductors Using a Combination of Organic Ligands

Most Bi-based semiconductors are incapable of photocatalytic reduction reaction from a thermodynamic view, owing to relatively positive conduction band potentials (E_CB ). Here, a novel Bi-based metal-organic framework (Bi-MBA, MBA=4-mercaptobenzoic acid) with excellent photocatalytic reduction activities is developed. The E_CB of Bi-MBA locates at -1.38 eV, which is able to efficiently reduce O₂ , Cr^VI and CO₂ . Theoretical calculations reveal the significant contribution of organic ligand (MBA) to the conduction band. Our results provide an effective route to improve the photocatalytic reduction activities of Bi-based photocatalysts.

The role of metal–organic porous frameworks in dual catalysis

Metal–organic frameworks (MOFs) are a valuable group of porous crystalline solids with inorganic and organic parts that can be used in dual catalysis.

The Effect of Surface Hydroxylation on MOF Formation on ALD Metal Oxides: MOF-525 on TiO2/Polypropylene for Catalytic Hydrolysis of Chemical Warfare Agent Simulants

Metal-organic framework (MOF) fibrous composites were synthesized in a variety of methods in attempt to incorporate the highly effective reactivity of MOFs into a more facile and applicable format. Recent advances have demonstrated incorporating a metal oxide nucleation surface or reactive layer promotes conformal, well-adhered MOF growth on substrates. These materials have demonstrated promising reactivity in capturing or degrading chemical warfare agents and simulants. Here, we examine the mechanisms for MOF nucleation from metal oxide thin films to explore why some metal oxide sources are better suited for one synthesis mechanism over another. We isolate metal oxide extent of hydroxylation as an indicative factor as to whether the film serves as a nucleation promoter or may be converted directly to the MOF thin films. MOF-525 growth on Al₂O₃, TiO₂, and ZnO coated fibers is demonstrated to corroborate these findings and used to degrade chemical warfare agent simulant dimethyl-4-nitrophenyl phosphate.

Triplet-Triplet Annihilation Upconversion in a MOF with Acceptor-Filled Channels

Photon upconversion has enjoyed increased interest in the last years due to its high potential for solar-energy harvesting and bioimaging. A challenge for triplet-triplet annihilation upconversion (TTA-UC) processes is to realize these features in solid materials without undesired phase segregation and detrimental dye aggregation. To achieve this, we combine a palladium porphyrin sensitizer and a 9,10-diphenylanthracene annihilator within a crystalline mesoporous metal-organic framework using an inverted design. In this modular TTA system, the framework walls constitute the fixed sensitizer, while caprylic acid coats the channels providing a solventlike environment for the mobile annihilator in the channels. The resulting solid material shows green-to-blue delayed upconverted emission with a luminescence lifetime of 373±5 μs, a threshold value of 329 mW cm-2 and a triplet-triplet energy transfer efficiency of 82 %. The versatile design allows straightforward changing of the acceptor amount and type.

Visible-light harvesting pyrene-based MOFs as efficient ROS generators

The utilization of reactive oxygen species (ROS) in organic transformations is of great interest due to their superior oxidative abilities under mild conditions. Recently, metal-organic frameworks (MOFs) have been developed as photosensitizers to transfer molecular oxygen to ROS for photochemical synthesis. However, visible-light responsive MOFs for oxygen activation remains scarce. Now we design and synthesize two porous MOFs, namely, PCN-822(M) (M = Zr, Hf), which are constructed by a 4,5,9,10-(K-region) substituted pyrene-based ligand, 4,4',4'',4'''-((2,7-di-tert-butylpyrene-4,5,9,10-tetrayl)tetrakis(ethyne-2,1-diyl))-tetrabenzoate (BPETB4-). With the extended π-conjugated pyrene moieties isolated on the struts, the derived MOFs are highly responsive to visible light, possessing a broad-band adsorption from 225-650 nm. As a result, the MOFs can be applied as efficient ROS generators under visible-light irradiation, and the hafnium-based MOF, PCN-822(Hf), can promote the oxidation of amines to imines by activating molecular oxygen via synergistic photo-induced energy and charge transfer.

Analysis of the Precursors, Simulants and Degradation Products of Chemical Warfare Agents

Recent advances in analysis of precursors, simulants and degradation products of chemical warfare agents (CWA) are reviewed. Fast and reliable analysis of precursors, simulants and CWA degradation products is extremely important at a time, when more and more terrorist groups and radical non-state organizations use or plan to use chemical weapons to achieve their own psychological, political and military goals. The review covers the open source literature analysis after the time, when the chemical weapons convention had come into force (1997). The authors stated that during last 15 years increased number of laboratories are focused not only on trace analysis of CWA (mostly nerve and blister agents) in environmental and biological samples, but the growing number of research are devoted to instrumental analysis of precursors and degradation products of these substances. The identification of low-level concentration of CWA degradation products is often more important and difficult than the original CWA, because of lower level of concentration and a very large number of compounds present in environmental and biological samples. Many of them are hydrolysis products and are present in samples in the ionic form. For this reason, two or three instrumental methods are used to perform a reliable analysis of these substances.

A Polyoxoniobate-Polyoxovanadate Double-Anion Catalyst for Simultaneous Oxidative and Hydrolytic Decontamination of Chemical Warfare Agent Simulants

A novel double-anion complex, H₁₃ [(CH₃ )₄ N]₁₂ [PNb₁₂ O₄₀ (V^V O)₂ ⋅(V^IV₄ O₁₂ )₂ ]⋅22 H₂ O (1), based on bicapped polyoxoniobate and tetranuclear polyoxovanadate was synthesized, characterized by routine techniques and used in the catalytic decontamination of chemical warfare agents. Under mild conditions, 1 catalyzes both hydrolysis of the nerve agent simulant, diethyl cyanophosphonate (DECP) and selective oxidation of the sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES). In the oxidative decontamination system 100 % CEES was transformed selectively to nontoxic 2-chloroethyl ethyl sulfoxide and vinyl ethyl sulfoxide using nearly stoichiometric 3 % aqueous H₂ O₂ with a turnover frequency (TOF) of 16 000 h^-1 . Importantly, the catalytic activity is maintained even after ten recycles and CEES is completely decontaminated in 3 mins without formation of the highly toxic sulfone by-product. A three-step oxidative mechanism is proposed.

Highly Stable Mesoporous Zirconium Porphyrinic Frameworks with Distinct Flexibility

The construction of highly stable metal-porphyrinic frameworks (MPFs) is appealing as these materials offer great opportunities for applications in artificial light-harvesting systems, gas storage, heterogeneous catalysis, etc. Herein, we report the synthesis of a novel mesoporous metal-porphyrinic framework (denoted as NUPF-1) and its catalytic properties. NUPF-1 is constructed from a new porphyrin linker and a Zr6 O8 structural building unit, possessing an unprecedented doubly interpenetrating scu net. The structure exhibits not only remarkable chemical and thermal stabilities, but also a distinct structural flexibility, which is seldom seen in metal-organic framework (MOF) materials. By the merit of high chemical stability, NUPF-1 could be easily post-metallized with [Ru3 (CO)12 ], and the resulting {NUPF-1-RuCO} is catalytically active as a heterogeneous catalyst for intermolecular C(sp(3) )-H amination. Excellent yields and good recyclability for amination of small substrates with various organic azides have been achieved.