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The selective removal of the β‐emitting pertechnetate ion (99TcO4−) from nuclear waste streams is technically challenging. Herein, a practical approach is proposed for the selective removal of 99TcO4− (or its surrogate ReO4−) under extreme conditions of high acidity, alkalinity, ionic strength, and radiation field. Hollow porous N‐doped carbon capsules loaded with ruthenium clusters (Ru@HNCC) are first prepared, then modified with a cationic polymeric network (R) containing imidazolium‐N+ units (Ru@HNCC‐R) for selective 99TcO4− and ReO4− binding. The Ru@HNCC‐R capsules offer high binding affinities for 99TcO4−/ReO4− under wide‐ranging conditions. An electrochemical redox process then transforms adsorbed ReO4− to bulk ReO3, delivering record‐high removal capacities, fast kinetics, and excellent long‐term durability for removing ReO4− (as a proxy for 99TcO4−) in a 3 m HNO3, simulated nuclear waste‐Hanford melter recycle stream and an alkaline high‐level waste stream (HLW) at the U.S. Savannah River Site (SRS). In situ Raman and X‐ray absorption spectroscopy (XAS) analyses showed that adsorbed Re(VII) is electrocatalytically reduced on Ru sites to a Re(IV)O2 intermediate, which can then be re‐oxidized to insoluble Re(VI)O3 for facile collection. This approach overcomes many of the challenges associated with the selective separation and removal of 99TcO4−/ReO4− under extreme conditions, offering new vistas for nuclear waste management and environmental remediation. [ABSTRACT FROM AUTHOR]

Optimizing the electronic structure of covalent organic framework (COF) photocatalysts is essential for maximizing photocatalytic activity. Herein, we report an isoreticular family of multivariate COFs containing chromenoquinoline rings in the COF structure and electron‐donating or withdrawing groups in the pores. Intramolecular donor‐acceptor (D‐A) interactions in the COFs allowed tuning of local charge distributions and charge carrier separation under visible light irradiation, resulting in enhanced photocatalytic performance. By optimizing the optoelectronic properties of the COFs, a photocatalytic uranium extraction efficiency of 8.02 mg/g/day was achieved using a nitro‐functionalized multicomponent COF in natural seawater, exceeding the performance of all COFs reported to date. Results demonstrate an effective design strategy towards high‐activity COF photocatalysts with intramolecular D‐A structures not easily accessible using traditional synthetic approaches. [ABSTRACT FROM AUTHOR]

One striking feature of enzyme is its controllable ability to trap substrates via synergistic or cooperative binding in the enzymatic pocket, which renders the shape‐selectivity of product by the confined spatial environment. The success of shape‐selective catalysis relies on the ability of enzyme to tune the thermodynamics and kinetics for chemical reactions. In emulation of enzyme's ability, we showcase herein a targeting strategy with the substrate being anchored on the internal pore wall of metal‐organic frameworks (MOFs), taking full advantage of the sterically kinetic control to achieve shape‐selectivity for the reactions. For this purpose, a series of binding site‐accessible metal metalloporphyrin‐frameworks (MMPFs) have been investigated to shed light on the nature of enzyme‐mimic catalysis. They exhibit a different density of binding sites that are well arranged into the nanospace with corresponding distances of opposite binding sites. Such a structural specificity results in a facile switch in selectivity from an exclusive formation of the thermodynamically stable product to the kinetic product. Thus, the proposed targeting strategy, based on the combination of porous materials and binding events, paves a new way to develop highly efficient heterogeneous catalysts for shifting selectivity. [ABSTRACT FROM AUTHOR]

Tuning catalytic centers in heterogeneous catalyst, both in a chemical and a spatial manner, is a powerful approach to improve the stability and the efficiency of catalysts. While the chemical aspects are largely understood, the spatial interactions around active sites, comprised of non‐covalent interactions, are difficult to maintain and challenging to study. Herein, the unique properties of covalent organic frameworks (COFs) are utilized to establish an ideal reaction environment for the hydrolysis of cellobiose and other common disaccharides in mild, metal‐free, and neutral aqueous conditions. The chosen COF, HCl‐PSA‐IM‐COF‐OMe ("HCl" for hydrochloric acid, "PSA" for propyl sulfonic acid, "IM" for imidazole, and "OMe" for methoxy), is modified to be ultra‐stable in aqueous conditions and possesses sulfonic acid groups for general acid catalysis and for enhanced hydrogen bonding with reactants as well as intraporous chloride anions for oxocarbenium intermediate stabilization. In addition, the system also relies on the differences in adsorptive binding behavior, Kads, of the reactants and the products to the functionalized framework and benefits from a separate physical, kinetic process to boost the catalytic cycle. Due to its stability in aqueous conditions, HCl‐PSA‐IM‐COF‐OMe can be recycled and maintains its hydrolytic properties for five cycles before regeneration is needed. [ABSTRACT FROM AUTHOR]

Developing adsorptive separation processes based on C2H6‐selective sorbents to replace energy‐intensive cryogenic distillation is a promising alternative for C2H4 purification from C2H4/C2H6 mixtures, which however remains challenging. During our studies on two isostructural metal–organic frameworks (Ni‐MOF 1 and Ni‐MOF 2), we found that Ni‐MOF 2 exhibited significantly higher performance for C2H6/C2H4 separation than Ni‐MOF‐1, as clearly established by gas sorption isotherms and breakthrough experiments. Density‐Functional Theory (DFT) studies showed that the unblocked unique aromatic pore surfaces within Ni‐MOF 2 induce more and stronger C−H⋅⋅⋅π with C2H6 over C2H4 while the suitable pore spaces enforce its high C2H6 uptake capacity, featuring Ni‐MOF 2 as one of the best porous materials for this very important gas separation. It generates 12 L kg−1 of polymer‐grade C2H4 product from equimolar C2H6/C2H4 mixtures at ambient conditions. [ABSTRACT FROM AUTHOR]

Water pollution is a growing threat to humanity due to the pervasiveness of contaminants in water bodies. Significant efforts have been made to separate these hazardous components to purify polluted water through various methods. However, conventional remediation methods suffer from limitations such as low uptake capacity or selectivity, and current water quality standards cannot be met. Recently, advanced porous materials (APMs) have shown promise in improved segregation of contaminants compared to traditional porous materials in uptake capacity and selectivity. These materials feature merits of high surface area and versatile functionality, rendering them ideal platforms for the design of novel adsorbents. This Review summarizes the development and employment of APMs in a variety of water treatments accompanied by assessments of task‐specific adsorption performance. Finally, we discuss our perspectives on future opportunities for APMs in water purification. [ABSTRACT FROM AUTHOR]

Asymmetric hydrogenation, a seminal strategy for the synthesis of chiral molecules, remains largely unmet in terms of activation by non‐metal sites of heterogeneous catalysts. Herein, as demonstrated by combined computational and experimental studies, we present a general strategy for integrating rationally designed molecular chiral frustrated Lewis pair (CFLP) with porous metal–organic framework (MOF) to construct the catalyst CFLP@MOF that can efficiently promote the asymmetric hydrogenation in a heterogeneous manner, which for the first time extends the concept of chiral frustrated Lewis pair from homogeneous system to heterogeneous catalysis. Significantly, the developed CFLP@MOF, inherits the merits of both homogeneous and heterogeneous catalysts, with high activity/enantio‐selectivity and excellent recyclability/regenerability. Our work not only advances CFLP@MOF as a new platform for heterogeneous asymmetric hydrogenation, but also opens a new avenue for the design and preparation of advanced catalysts for asymmetric catalysis. [ABSTRACT FROM AUTHOR]

Seawater contains uranium at a concentration of ≈3.3 ppb, thus representing a rich and sustainable nuclear fuel source. Herein, an adsorption–electrocatalytic platform is developed for uranium extraction from seawater, comprising atomically dispersed indium anchored on hollow nitrogen‐doped carbon capsules functionalized with flexible amidoxime moieties (In–Nx–C–R, where R denotes amidoxime groups). In–Nx–C–R exhibits excellent uranyl capture properties, enabling a uranium removal rate of 6.35 mg g−1 in 24 h, representing one of the best uranium extractants reported to date. Importantly, In–Nx–C–R demonstrates exceptional selectivity for uranium extraction relative to vanadium in seawater (8.75 times more selective for the former). X‐ray absorption spectroscopy (XAS) reveals that the amidoxime groups serve as uranyl chelating sites, thus allowing selective adsorption over other ions. XAS and in situ Raman results directly indicate that the absorbed uranyl can be electrocatalytically reduced to an unstable U(V) intermediate, then re‐oxidizes to U(VI) in the form of insoluble Na2O(UO3·H2O)x for collection, through reversible single electron transfer processes involving InNx sites. These results provide detailed mechanistic understanding of the uranium extraction process at a molecular level. This work provides a roadmap for the adsorption–electrocatalytic extraction of uranium from seawater, adding to the growing suite of technologies for harvesting valuable metals from the earth's oceans. [ABSTRACT FROM AUTHOR]

Removal of radioactive technetium‐99 (99TcO4−) from water by effective adsorbents is highly desired but remains a challenge. The currently used resin adsorbents possess several obstacles, such as slow adsorption kinetics and low adsorption capacity. To address these issues, herein a type of fibrous adsorbent with porosity and hyper‐branched quaternary ammonium groups, namely porous cationic electrospun fibers (PCE fibers), is successfully prepared. PCE fibers can remove 97% of 99TcO4− within 1 min and the equilibrium time of 99% removal is 20 min. The predicted maximum adsorption capacity toward the surrogate ReO4− can reach 826 mg g−1, which is higher than the state of art anion‐exchange resins and most of the other reported adsorbents. Furthermore, PCE fibers have good selectivity for ReO4− in the presence of competitive anions, and can retain ReO4− uptake under extreme conditions including high acid–base and gamma irradiation. Importantly, PCE fibrous adsorptive membrane is employed for dynamic ReO4− removal from simulated Hanford LAW stream with a processing capacity of 600 kg simulated stream per kilogram PCE fibers. The excellent performance highlights the advantages of PCE fibers over traditional resins in technetium removal. [ABSTRACT FROM AUTHOR]

A vast amount of energy can be extracted from the untapped low‐grade heat from sources below 100 °C and the Gibbs free energy from salinity gradients. Therefore, a process for simultaneous and direct conversion of these energies into electricity using permselective membranes was developed in this study. These membranes screen charges of ion flux driven by the combined salinity and temperature gradients to achieve thermo‐osmotic energy conversion. Increasing the charge density in the pore channels enhanced the permselectivity and ion conductance, leading to a larger osmotic voltage and current. A 14‐fold increase in power density was achieved by adjusting the ionic site population of covalent organic framework (COF) membranes. The optimal COF membrane was operated under simulated estuary conditions at a temperature difference of 60 K, which yielded a power density of ≈231 W m−2, placing it among the best performing upscaled membranes. The developed system can pave the way to the utilization of the enormous supply of untapped osmotic power and low‐grade heat energy, indicating the tremendous potential of using COF membranes for energy conversion applications. [ABSTRACT FROM AUTHOR]

The capture of the xenon and krypton from nuclear reprocessing off‐gas is essential to the treatment of radioactive waste. Although various porous materials have been employed to capture Xe and Kr, the development of high‐performance adsorbents capable of trapping Xe/Kr at very low partial pressure as in the nuclear reprocessing off‐gas conditions remains challenging. Herein, we report a self‐adjusting metal‐organic framework based on multiple weak binding interactions to capture trace Xe and Kr from the nuclear reprocessing off‐gas. The self‐adjusting behavior of ATC‐Cu and its mechanism have been visualized by the in‐situ single‐crystal X‐ray diffraction studies and theoretical calculations. The self‐adjusting behavior endows ATC‐Cu unprecedented uptake capacities of 2.65 and 0.52 mmol g−1 for Xe and Kr respectively at 0.1 bar and 298 K, as well as the record Xe capture capability from the nuclear reprocessing off‐gas. Our work not only provides a benchmark Xe adsorbent but proposes a new route to construct smart materials for efficient separations. [ABSTRACT FROM AUTHOR]

Uncontrolled mixing remains the primary hurdle impeding the practical application of reverse electrodialysis (RED) to harvest Gibbs free energy in the form of salinity gradients. Improving the permselectivity of membranes is therefore essential, with ionic density being one of the most critical factors. Herein, it is systematically investigated how the charge population in nanofluidic membranes affects the ionic charge separation and consequently the accompanying power density. To establish this relationship, the effect of the ionic density is decoupled from the impact of pore structure using a multivariate strategy to construct covalent‐organic‐framework‐based membranes, in which the content of ionic sites can be precisely manipulated from 0 to 0.18 C m−2, a range that has rarely been experimentally explored. Beyond the region reported (0.002–0.06 C m−2), wherein increasing pore surface charge density of the membrane enhances permselectivity and leads to a greater osmotic voltage, a sharp volcano‐like curve is observed. The optimal membrane affords record‐high power outputs among membrane systems, one order of magnitude higher than the value set for commercialization. The study provides insights into the impact of ionic density of the membrane on osmotic energy harvesting that can guide RED stack design to advance sustainable energy generation from natural salinity gradients. [ABSTRACT FROM AUTHOR]

Titanium metal–organic frameworks (Ti‐MOFs), as an appealing type of artificial photocatalyst, have shown great potential in the field of solar energy conversion due to their well‐studied photoredox activity (similar to TiO2) and good optical responsiveness of linkers, which serve as the antenna to absorb visible‐light. Although much effort has been dedicated to developing Ti‐MOFs with high photocatalytic activity, their solar energy conversion performances are still poor. Herein, we have implemented a covalent‐integration strategy to construct a series of multivariate Ti‐MOF/COF hybrid materials PdTCPP⊂PCN‐415(NH2)/TpPa (composites 1, 2, and 3), featuring excellent visible‐light utilization, a suitable band gap, and high surface area for photocatalytic H2 production. Notably, the resulting composites demonstrated remarkably enhanced visible‐light‐driven photocatalytic H2 evolution performance, especially for the composite 2 with a maximum H2 evolution rate of 13.98 mmol g−1 h−1 (turnover frequency (TOF)=227 h−1), which is much higher than that of PdTCPP⊂PCN‐415(NH2) (0.21 mmol g−1 h−1) and TpPa (6.51 mmol g−1 h−1). Our work thereby suggests a new approach to highly efficient photocatalysts for H2 evolution and beyond. [ABSTRACT FROM AUTHOR]

The structural advantages of metal‐organic frameworks (MOFs) can facilitate wide applications in the field of catalysis, including oxidation, hydrogenation, acetalization, transesterification, catalytic cracking, and so on. The efficiency of catalysis is closely related to the synergy between active center, auxiliary center, and microenvironment. Researchers can customize MOFs according to the needs of catalytic reactions, and many strategies were established for boosting catalytic performance. In this review, we aim to summarize and illustrate recent progress in the nanospace engineering of MOFs. Generally, MOFs were engineered mainly from the following aspects: 1) Regulation of pore size, including micropores, mesopores, and macropores. 2) Engineering of encapsulated active species, such as metal nanoparticles, quantum dots, polyoxometalates, enzymes, etc. 3) Engineering of MOFs morphology from zero dimension to three‐dimension. 4) Controllable integration of MOFs with multi‐strategies. 5) Construction of multivariate MOFs via introducing multiple or mixed organic functional groups into the existing framework. Besides, for further low cost and practical applications, challenges for MOFs as green and sustainable catalysts are also discussed. [ABSTRACT FROM AUTHOR]

The enantioselective separation of racemic mixtures is highly important in the pharmaceutical, food and agrochemical sector. Metal‐organic frameworks, as a class of highly porous materials are emerging as highly efficient and selective platforms for chiral recognition and separation owing to their ultrahigh porosities, functionalized pore walls, controllable pore chemistry and presence of highly ordered chiral recognition sites. In this review, we summarize the progress made in the synthesis of chiral MOFs via direct and indirect methods, followed by their applications in some important chiral separations of alcohols, drugs, amino acids, biologically relevant molecules and important chiral organic mixtures. The developments in chiral MOF membranes as thin films for practical industrial use are also explored. Finally, the outlook for the MOFs as emerging platforms for enantioseparation and the future directions are discussed. [ABSTRACT FROM AUTHOR]

Acetylene is an important precursor in the petrochemical, plastics and electronic industries, as well as the prominent fuel for welding and metal cutting. The high flammability and explosive nature of acetylene, however hinder its safe storage and transportation. Porous materials are highly promising for acetylene storage and as they can provide strong binding interactions and an optimal pore environment. Furthermore, high selectivity and separation can be achieved for acetylene over other gases such as CO2 and small hydrocarbons. In this review, we divulge into the recent advancements and paradigms in acetylene storage and separation with a focus on porous metal‐organic frameworks (MOFs). An overview of the benchmark materials for acetylene storage and separation, along with some recent developments in the strategies to balance the trade‐off between the uptake capacity and selectivity is provided. The approaches of designing small pores and highly functionalized pore environments for strong binding with the acetylene adsorbate; along with the pore space partition, window space directed assembly and inverse CO2/C2H2 adsorption for the separation of acetylene from CO2, CH4, C2H4 and other hydrocarbons are reviewed to provide a summary and help further augment the research in this direction. [ABSTRACT FROM AUTHOR]

Biomimetic metal‐organic frameworks have attracted great attention as they can be used as bio‐inspired models, allowing us to gain important insights into how large biological molecules function as catalysts. In this work, we report the synthesis and utilization of such a metal‐metalloporphyrin framework (MMPF) that is constructed from a custom‐designed ligand as an efficient halogen bond donor catalyst for Diels–Alder reactions under ambient conditions. The implementation of fabricated halogen bonding capsule as binding pocket with high‐density C−Br bonds enabled the use of halogen bonding to facilitate organic transformations in their three‐dimensional cavities. Through combined experimental and computational studies, we showed that the substrate molecules diffuse through the pores of the MMPF, establishing a host‐guest system via the C−Br⋅⋅⋅π interaction. The formation of halogen bonds is a plausible explanation for the observed boosted catalytic efficiency in Diels–Alder reactions. Moreover, the unique capability of MMPF highlights new opportunities in using artificial non‐covalent binding pockets as highly tunable and selective catalytic materials. [ABSTRACT FROM AUTHOR]

Guided by a second‐sphere interaction strategy, we fabricated a Tb(III)‐based metal—organic framework (MMCF‐4) for turn‐on sensing of methyl amine with ultra‐low detection limit and high turn‐on efficiency. MMCF‐4 features lanthanide nodes shielded in a nonacoordinate geometry along with secondary coordination spheres that are densely populated with H‐bond interacting sites. Nonradiative routes were inhibited by binding‐induced rigidification of the ligand on the second coordination sphere, resulting in luminescence amplification. Such remote interacting mechanism involved in the turn‐on sensing event was confirmed by single‐crystal X‐ray diffraction and molecular dynamic simulation studies. The design of both primary and secondary coordination spheres of Tb(III) enabled the first turn‐on sensing of organic amines in aqueous conditions. Our work suggests a promising strategy for high‐performance turn‐on sensing for Ln‐MOFs and luminous materials driven by other metal chromophores. [ABSTRACT FROM AUTHOR]

Accumulation of high concentrations of Al(III) in body has a direct impact on health and therefore, the trace detection of Al(III) has been a matter for substantial concern. An anionic metal organic framework ({[Me2NH2]0.5[Co(DATRz)0.5(NH2BDC)] ⋅ xG}n; 1; HDATRz=3,5‐diamino‐1,2,4‐triazole, H2NH2‐BDC=2‐amino‐1,4‐benzenedicarboxylic acid, G=guest molecule) composed of two types of secondary building units (SBU) and channels of varying sizes was synthesized by employing a rational design mixed ligand synthesis approach. Free −NH2 groups on both the ligands are immobilized onto the pore surface of the MOF which acts as a superior luminescent sensor for turn‐on Al(III) detection. Furthermore, the large channels could allow the counter‐ions to pass through and get exchanged to selectively detect Al(III) in presence of other seventeen metal ions with magnificent luminescence enhancement. The observed limit of detection is as low as 17.5 ppb, which is the lowest among the MOF‐based sensors achieved so far. To make this detection approach simple, portable and economic, we demonstrate MOF filter paper test for real time naked eye observation. [ABSTRACT FROM AUTHOR]

Adsorption‐based cooling is an energy‐efficient renewable‐energy technology that can be driven using low‐grade industrial waste heat and/or solar heat. Here, we report the first exploration of fluorocarbon adsorption using porous covalent organic polymers (COPs) for this cooling application. High fluorocarbon R134a equilibrium capacities and unique overall linear‐shaped isotherms are revealed for the materials, namely COP‐2 and COP‐3. The key role of mesoporous defects on this unusual adsorption behavior was demonstrated by molecular simulations based on atomistic defect‐containing models built for both porous COPs. Analysis of simulated R134a adsorption isotherms for various defect‐containing atomistic models of the COPs shows a direct correlation between higher fluorocarbon adsorption capacities and increasing pore volumes induced by defects. Combined with their high porosities, excellent reversibility, fast kinetics, and large operating window, these defect‐containing porous COPs are promising for adsorption‐based cooling applications. [ABSTRACT FROM AUTHOR]

Various robust, crystalline, and porous organic frameworks based on in situ‐formed imine‐linked oligomers were investigated. These oligomers self‐assembled through collaborative intermolecular hydrogen bonding interactions via liquid–liquid interfacial reactions. The soluble oligomers were kinetic products with multiple unreacted aldehyde groups that acted as hydrogen bond donors and acceptors and directed the assembly of the resulting oligomers into 3D frameworks. The sequential formation of robust covalent linkages and highly reversible hydrogen bonds enforced long‐range symmetry and facilitated the production of large single crystals, with structures that were unambiguously determined by single‐crystal X‐ray diffraction. The unique hierarchical arrangements increased the steric hindrance of the imine bond, which prevented attacks from water molecules, greatly improving the stability. The multiple binding sites in the frameworks enabled rapid sequestration of micropollutant in water. [ABSTRACT FROM AUTHOR]

Herein, a dynamic spacer installation (DSI) strategy has been implemented to construct a series of multifunctional metal—organic frameworks (MOFs), LIFM‐61/31/62/63, with optimized pore space and pore environment for ethane/ethylene separation. In this respect, a series of linear dicarboxylic acids were deliberately installed in the prototype MOF, LIFM‐28, leading to a dramatically increased pore volume (from 0.41 to 0.82 cm3 g−1) and reduced pore size (from 11.1×11.1 Å2 to 5.6×5.6 Å2). The increased pore volume endows the multifunctional MOFs with much higher ethane adsorption capacity, especially for LIFM‐63 (4.8 mmol g−1), representing nearly three times as much ethane as the prototypical counterpart (1.7 mmol g−1) at 273 K and 1 bar. Meanwhile, the reduced pore size imparts enhanced ethane/ethylene selectivity of the multifunctional MOFs. Theoretical calculations and dynamic breakthrough experiments confirm that the DSI is a promising approach for the rational design of multifunctional MOFs for this challenging task. [ABSTRACT FROM AUTHOR]

Biological pores regulate the cellular traffic of a diverse collection of molecules, often with extremely high selectivity. Given the ubiquity of charge‐based separation in nature, understanding the link between the charged functionalities and the ion transport activities is essential for designing delicate separations, with the correlation being comparatively underdeveloped. Herein, the effect of charge density from the impact of pore structure is decoupled using a multivariate strategy for the construction of covalent organic framework‐based membranes. How the density of charged sites in the nanofluidic membranes affect the ion transport activity with particular emphasis on Li+ and Mg2+ ions, relevant to the challenge of salt‐lake lithium mining is systematically investigated. Systematic control of the charge distribution produces membranes with numerous advantages, overcoming the long‐term challenge of Li+/Mg2+ separation. The top membrane exhibits an outstanding equilibrium selectivity for Li+ over Mg2+ and operational stability under diffusion dialysis and electrodialysis conditions (Li+/Mg2+ up to 500), qualifying it as a potential candidate for lithium extraction. It is anticipated that the developed nanofluidic membrane platform can be further leveraged to tackle other challenges in controlled separation processes. [ABSTRACT FROM AUTHOR]

Porous materials with open metal sites have been investigated to separate various gas mixtures. However, open metal sites show the limitation in the separation of some challenging gas mixtures, such as C2H2/CO2. Herein, we propose a new type of ultra‐strong C2H2 nano‐trap based on multiple binding interactions to efficiently capture C2H2 molecules and separate C2H2/CO2 mixture. The ultra‐strong acetylene nano‐trap shows a benchmark Qst of 79.1 kJ mol−1 for C2H2, a record high pure C2H2 uptake of 2.54 mmol g−1 at 1×10−2 bar, and the highest C2H2/CO2 selectivity (53.6), making it as a new benchmark material for the capture of C2H2 and the separation of C2H2/CO2. The locations of C2H2 molecules within the MOF‐based nanotrap have been visualized by the in situ single‐crystal X‐ray diffraction studies, which also identify the multiple binding sites accountable for the strong interactions with C2H2. [ABSTRACT FROM AUTHOR]

Attributed to the unique topological complexity and elegant beauty, Borromean systems are attracting intense attention. However, at present, the construction of Borromean linked organic polymers remains a challenge. To address this formidable challenge, we developed a supramolecular‐synthon‐driven approach to fabricate Borromean linked organic polymer. The solvothermal condensation reaction of a judiciously selected trigonal pyramidal building block, 1,3,5‐Tris(4‐aminophenyl)adamantane, with linear dialdehyde building blocks allowed the construction of two rare covalent organic frameworks (COFs) with high crystallinity and robustness. Structure refinement unveiled the successful formation of entangled 2D→2D Borromean arrayed structures. Both the two COFs were of microporosity and thus demonstrated the potentials for gas separation. The successful synthesis of the first two Borromean linked organic polymers paves the avenue to expand the supramolecular‐synthon‐driven approach to other building blocks and topologies, and broadens the family and scope of COFs. [ABSTRACT FROM AUTHOR]

Preorganization is a basic design principle used by nature that allows for synergistic pathways to be expressed. Herein, a full account of the conceptual and experimental development from randomly distributed functionalities to a convergent arrangement that facilitates cooperative binding is given, thus conferring exceptional affinity toward the analyte of interest. The resulting material with chelating groups populated adjacently in a spatially locked manner displays up to two orders of magnitude improvement compared to a random and isolated manner using uranium sequestration as a model application. This adsorbent shows exceptional extraction efficiencies, capable of reducing the uranium concentration from 5 ppm to less than 1 ppb within 10 min, even though the system is permeated with high concentrations of competing ions. The efficiency is further supported by its ability to extract uranium from seawater with an uptake capability of 5.01 mg g−1, placing it among the highest‐capacity seawater uranium extraction materials described to date. The concept presented here uncovers a new paradigm in the design of efficient sorbent materials by manipulating the spatial distribution to amplify the cooperation of functions. [ABSTRACT FROM AUTHOR]

A photoactive porphyrinic metal−organic framework (MOF) has been prepared by exchanging Ti into a Zr‐based MOF precursor. The resultant mixed‐metal Ti/Zr porphyrinic MOF demonstrates much‐improved efficiency for gas‐phase CO2 photoreduction into CH4 and CO under visible‐light irradiation using water vapor compared to the parent Zr‐MOF. Insightful studies have been conducted to probe the photocatalysis processes. This work provides the first example of gas‐phase CO2 photoreduction into methane without organic sacrificial agents on a MOF platform, thereby paving an avenue for developing MOF‐based photocatalysts for application in CO2 photoreduction and other types of photoreactions. [ABSTRACT FROM AUTHOR]

In this special issue, M. El-Kaderi and co-workers reported the synthesis of a redox-active pyrene-containing polyimide COF (PICOF-1) by linker exchange using an imine-linked COFs as a template (article 2200782). In order to improve the production efficiency of COFs, He and co-workers reported a "thermally promoted homogenous-floating-concentrating" strategy for the rapid synthesis of highly crystalline triazine/hydroxyl-rich COFs under mild conditions (article 2200786). Covalent organic frameworks (COFs) are a class of crystalline, porous polymers formed from the reversible covalent reactions between organic building blocks, resulting in ordered structure, permanent porosity, and topologically diversed. [Extracted from the article]

To offset the environmental impact of platinum‐group element (PGE) mining, recycling techniques are being explored. Porous organic polymers (POPs) have shown significant promise owing to their selectivity and ability to withstand harsh conditions. A series of pyridine‐based POP nanotraps, POP‐Py, POP‐pNH2‐Py, and POP‐oNH2‐Py, have been designed and systematically explored for the capture of palladium, one of the most utilized PGEs. All of the POP nanotraps demonstrated record uptakes and rapid capture, with the amino group shown to be vital in improving performance. Further testing on the POP nanotrap regeneration and selectivity found that POP‐oNH2‐Py outperformed POP‐pNH2‐Py. Single‐crystal X‐ray analysis indicated that POP‐oNH2‐Py provided a stronger complex compared to POP‐pNH2‐Py owing to the intramolecular hydrogen bonding between the amino group and coordinated chlorine molecules. These results demonstrate how slight modifications to adsorbents can maximize their performance. [ABSTRACT FROM AUTHOR]

An enzyme formulation using customized enzyme activators (metal ions) to directly construct metal–organic frameworks (MOFs) as enzyme protective carriers is presented. These MOF carriers can also serve as the disintegrating agents to simultaneously release enzymes and their activators during biocatalysis with boosted activities. This highly efficient enzyme preparation combines enzyme immobilization (enhanced stability, easy operation) and homogeneous biocatalysis (fast diffusion, high activity). The MOF serves as an ion pump that continuously provides metal ion activators that greatly promote the enzymatic activities (up to 251 %). This MOF–enzyme composite demonstrated an excellent protective effect against various perturbation environments. A mechanistic investigation revealed that the spontaneous activator/enzyme release and ion pumping enable enzymes to sufficiently interact with their activators owing to the proximity effects, leading to a boost in biocatalytic performance. [ABSTRACT FROM AUTHOR]

Fabrication of zeolite‐like metal–organic frameworks (ZMOFs) for advanced applications, such as enzyme immobilization, is of great interest but is a great synthetic challenge. Herein, we have developed a new strategy using proteins as structure‐directed agents to direct the formation of new ZMOFs that can act as versatile platforms for the in situ encapsulation of proteins under ambient conditions. Notably, protein incorporation directs the formation of a ZMOF with a sodalite (sod) topology instead of a non‐porous diamondoid (dia) topology under analogous synthetic conditions. Histidines in proteins play a crucial role in the observed templating effect. Modulating histidine content thereby influenced the resultant MOF product (from dia to dia + sod mixture and, ultimately, to sod MOF). Moreover, the resulting ZMOF‐incorporated proteins preserved their activity even after exposure to high temperatures and organic solvents, demonstrating their potential for biocatalysis and biopharmaceutical applications. [ABSTRACT FROM AUTHOR]

Herein, for the first time, we present the successful synthesis of a novel two‐dimensional corrole‐based covalent organic framework (COF) by reacting the unusual approximately T‐shaped 5,10,15‐tris(p‐aminophenyl)corrole H3TPAPC with terephthalaldehyde, which adopts desymmetrized hcb topology and consists of a staggered AB stacking structure with elliptical pores. The resultant corrole‐based COF, TPAPC‐COF, exhibits high crystallinity and excellent chemical stability. The combination of extended π‐conjugated backbone and interlayer noncovalent π–π interactions endows TPAPC‐COF with excellent absorption capability in the entire visible‐light and even near‐infrared regions. Moreover, this work suggests the promise of TPAPC‐COF as a new class of photoactive material for efficient singlet‐oxygen generation with potential photodynamic therapy application as demonstrated by in vitro anticancer studies. [ABSTRACT FROM AUTHOR]

Developing new materials for the fabrication of proton exchange membranes (PEMs) for fuel cells is of great significance. Herein, a series of highly crystalline, porous, and stable new covalent organic frameworks (COFs) have been developed by a stepwise synthesis strategy. The synthesized COFs exhibit high hydrophilicity and excellent stability in strong acid or base (e.g. 12 m NaOH or HCl) and boiling water. These features make them ideal platforms for proton conduction applications. Upon loading with H3PO4, the COFs (H3PO4@COFs) realize an ultrahigh proton conductivity of 1.13×10−1 S cm−1, the highest among all COF materials, and maintain high proton conductivity across a wide relative humidity (40–100 %) and temperature range (20–80 °C). Furthermore, membrane electrode assemblies were fabricated using H3PO4@COFs as the solid electrolyte membrane for proton exchange resulting in a maximum power density of 81 mW cm−2 and a maximum current density of 456 mA cm−2, which exceeds all previously reported COF materials. [ABSTRACT FROM AUTHOR]

As a major greenhouse gas, methane, which is directly vented from the coal‐mine to the atmosphere, has not yet drawn sufficient attention. To address this problem, we report a methane nano‐trap that features oppositely adjacent open metal sites and dense alkyl groups in a metal–organic framework (MOF). The alkyl MOF‐based methane nano‐trap exhibits a record‐high methane uptake and CH4/N2 selectivity at 298 K and 1 bar. The methane molecules trapped within the alkyl MOF were crystalographically identified by single‐crystal X‐ray diffraction experiments, which in combination with molecular simulation studies unveiled the methane adsorption mechanism within the MOF‐based nano‐trap. The IAST calculations and the breakthrough experiments revealed that the alkyl MOF‐based methane nano‐trap is a new benchmark for CH4/N2 separation, thereby providing a new perspective for capturing methane from coal‐mine methane to recover fuel and reduce greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

Herein, we show how the spatial environment in the functional pores of covalent organic frameworks (COFs) can be manipulated in order to exert control in catalysis. The underlying mechanism of this strategy relies on the placement of linear polymers in the pore channels that are anchored with catalytic species, analogous to outer‐sphere residue cooperativity within the active sites of enzymes. This approach benefits from the flexibility and enriched concentration of the functional moieties on the linear polymers, enabling the desired reaction environment in close proximity to the active sites, thereby impacting the reaction outcomes. Specifically, in the representative dehydration of fructose to produce 5‐hydroxymethylfurfural, dramatic activity and selectivity improvements have been achieved for the active center of sulfonic acid groups in COFs after encapsulation of polymeric solvent analogues 1‐methyl‐2‐pyrrolidinone and ionic liquid. [ABSTRACT FROM AUTHOR]

Frustrated Lewis pairs (FLPs) have recently been advanced as efficient metal‐free catalysts for catalytic hydrogenation, but their performance in chemoselective hydrogenation, particularly in heterogeneous systems, has not yet been achieved. Herein, we demonstrate that, via tailoring the pore environment within metal–organic frameworks (MOFs), FLPs not only can be stabilized but also can develop interesting performance in the chemoselective hydrogenation of α,β‐unsaturated organic compounds, which cannot be achieved with FLPs in a homogeneous system. Using hydrogen gas under moderate pressure, the FLP anchored within a MOF that features open metal sites and hydroxy groups on the pore walls can serve as a highly efficient heterogeneous catalyst to selectively reduce the imine bond in α,β‐unsaturated imine substrates to afford unsaturated amine compounds. [ABSTRACT FROM AUTHOR]

Photomechanical molecular crystals are receiving much attention due to their efficient conversion of light into mechanical work and advantages including faster response time; higher Young's modulus; and ordered structure, as measured by single‐crystal X‐ray diffraction. Recently, various photomechanical crystals with different motions (contraction, expansion, bending, fragmentation, hopping, curling, and twisting) are appearing at the forefront of smart materials research. The photomechanical motions of these single crystals during irradiation are triggered by solid‐state photochemical reactions and accompanied by phase transformation. This Minireview summarizes recent developments in growing research into photoresponsive molecular crystals. The basic mechanisms of different kinds of photomechanical materials are described in detail; recent advances in photomechanical crystals for promising applications as smart materials are also highlighted. [ABSTRACT FROM AUTHOR]

The separation of racemic compounds is important in many fields, such as pharmacology and biology. Taking advantage of the intrinsically strong chiral environment and specific interactions featured by biomolecules, here we contribute a general strategy is developed to enrich chirality into covalent organic frameworks (COFs) by covalently immobilizing a series of biomolecules (amino acids, peptides, enzymes) into achiral COFs. Inheriting the strong chirality and specific interactions from the immobilized biomolecules, the afforded biomolecules⊂COFs serve as versatile and highly efficient chiral stationary phases towards various racemates in both normal and reverse phase of high‐performance liquid chromatography (HPLC). The different interactions between enzyme secondary structure and racemates were revealed by surface‐enhanced Raman scattering studies, accounting for the observed chiral separation capacity of enzymes⊂COFs. COF chirality: A general and efficient strategy has been developed to introduce chirality into covalent organic frameworks (COFs) by covalently immobilizing biomolecules into achiral COFs. The biomolecules⊂COFs can serve as chiral stationary phases for efficient chiral separation of a broad range of racemates. [ABSTRACT FROM AUTHOR]

The removal of C2H2 and C2H6 from C2H4 streams is of great significance for feedstock purification to produce polyethylene and other commodity chemicals but the simultaneous adsorption of C2H6 and C2H2 over C2H4 from a ternary mixture has never been realized. Herein, a robust metal–organic framework, TJT‐100, was designed and synthesized, which demonstrates remarkably selective adsorption of C2H2 and C2H6 over C2H4. Breakthrough experiments show that TJT‐100 can be used as an adsorbent for high‐performance purification of C2H4 from a ternary mixture of C2H2/C2H4/C2H6 (0.5:99:0.5) to afford a C2H4 purity greater than 99.997 %, beyond that required for ethylene polymerization. Computational studies reveal that the uncoordinated carboxylate oxygen atoms and coordinated water molecules pointing towards the pore can trap C2H2 and C2H6 through the formation of multiple C−H⋅⋅⋅O electrostatic interactions, while the corresponding C2H4–framework interaction is unfavorable. A robust porous metal–organic framework was synthesized and utilized for the highly selective separation of C2H4 from a ternary mixture of C2 hydrocarbons. After a single operation, the C2H4 purity of the outlet was greater than 99.997 %. [ABSTRACT FROM AUTHOR]

Abstract: Artificial muscles triggered by light are of great importance, especially for the development of non‐contact and remotely controlled materials. Common materials for synthesis of photoinduced artificial muscles typically rely on polymer‐based photomechanical materials. Herein, we are able to prepare artificial muscles using a mixed‐matrix membrane strategy to incorporate photomechanical molecular crystals with connective polymers (e.g. PVDF). The formed hybrid materials inherit not only the advantages of the photomechanical crystals, including faster light response, higher Young's modulus and ordered structure, but also the elastomer properties from polymers. This new type of artificial muscles demonstrates various muscle movements, including lifting objects, grasping objects, crawling and swimming, triggered by light irradiation. These results open a new direction to prepare light‐driven artificial muscles based on molecular crystals. [ABSTRACT FROM AUTHOR]

Abstract: Industrial synthesis is driven by a delicate balance of the value of the product against the cost of production. Catalysts are often employed to ensure product turnover is economically favorable by ensuring energy use is minimized. One method, which is gaining attention, involves cooperative catalytic systems. By inserting a flexible polymer into a metal–organic framework (MOF) host, the advantages of both components work synergistically to create a composite that efficiently fixes carbon dioxide to transform various epoxides into cyclic carbonates. The resulting material retains high yields under mild conditions with full reusability. By quantitatively studying the kinetic rates, the activation energy was calculated, for a physical mixture of the catalyst components to be about 50 % higher than that of the composite. Through the unification of two catalytically active components, a new opportunity opens up for the development of synergistic systems in multiple applications. [ABSTRACT FROM AUTHOR]

In their Research Article (e202303129), Hui Yang, Xiangke Wang, Shengqian Ma et al. report a strategy to regulate local charge distributions and intramolecular donor-acceptor interactions in multivariate covalent organic frameworks. Keywords: Charge Distribution; Covalent Organic Frameworks; Donor-Acceptor; Photocatalysis; Post-Synthesis EN Charge Distribution Covalent Organic Frameworks Donor-Acceptor Photocatalysis Post-Synthesis 1 1 1 07/21/23 20230724 NES 230724 B Covalent Organic Frameworks b . [Extracted from the article]

Abstract: Herein, we report that a new flexible coordination network, NiL2 (L=4‐(4‐pyridyl)‐biphenyl‐4‐carboxylic acid), with diamondoid topology switches between non‐porous (closed) and several porous (open) phases at specific CO2 and CH4 pressures. These phases are manifested by multi‐step low‐pressure isotherms for CO2 or a single‐step high‐pressure isotherm for CH4. The potential methane working capacity of NiL2 approaches that of compressed natural gas but at much lower pressures. The guest‐induced phase transitions of NiL2 were studied by single‐crystal XRD, in situ variable pressure powder XRD, synchrotron powder XRD, pressure‐gradient differential scanning calorimetry (P‐DSC), and molecular modeling. The detailed structural information provides insight into the extreme flexibility of NiL2. Specifically, the extended linker ligand, L, undergoes ligand contortion and interactions between interpenetrated networks or sorbate–sorbent interactions enable the observed switching. [ABSTRACT FROM AUTHOR]

Abstract: A majority of metal–organic frameworks (MOFs) fail to preserve their physical and chemical properties after exposure to acidic, neutral, or alkaline aqueous solutions, therefore limiting their practical applications in many areas. The strategy demonstrated herein is the design and synthesis of an organic ligand that behaves as a buffer to drastically boost the aqueous stability of a porous MOF (JUC‐1000), which maintains its structural integrity at low and high pH values. The local buffer environment resulting from the weak acid–base pairs of the custom‐designed organic ligand also greatly facilitates the performance of JUC‐1000 in the chemical fixation of carbon dioxide under ambient conditions, outperforming a series of benchmark catalysts. [ABSTRACT FROM AUTHOR]