Metal-Organic Frameworks for Water Harvesting and Concurrent Carbon Capture: A Review for Hygroscopic Materials

Bioinspired Water-Stable Sc-MOF with Amino-Barb Vigreux-Type Channels for One-Step Ethylene Purification

We report a bioinspired Sc-MOF NTUniv-77 with Vigreux-type channels and amino-barb protrusions that enable selective gas adsorption. The unique amino group arrangement facilitates multistage cascade separation, enhancing C2H2 and C2H6 adsorption while allowing high-purity C2H4 purification in a single step. NTUniv-77 shows outstanding separation performance, with a C2H2/C2H4 (1:99) selectivity of 42 and C2H6/C2H4 (1:9) selectivity of 3.6, surpassing benchmark MOFs. GCMC simulations reveal that hydrogen bonding interactions at amino-barb sites are key to its efficiency. Breakthrough experiments confirmed the efficient separation of C2 gases, yielding high-purity C2H4 with a production capacity of 1.29 mmol g-1.

Hydrolytically Stable Phosphonate-Based Metal-Organic Frameworks for Harvesting Water from Low Humidity Air

Harvesting water from air offers a promising solution to the global water crisis. However, existing sorbents often struggle in arid climates due to limitations such as low sorption capacities, hydrolytic instability, slow mass transport, high desorption enthalpy, and costly operation. Phosphonate-based metal-organic frameworks (MOFs), known for their exceptional water stability, have not been extensively explored for water harvesting. This study systematically investigates the performance of STA-12 (M═Co, Ni, Mg) and STA-16 (M═Co, Ni), a series of stable phosphonate-based MOFs, as water sorbents. STA-12 MOFs demonstrate remarkable adsorption at ultra-low humidity (<10%), while STA-16(Co) exhibits a high water uptake capacity of 0.54 g g-1 at 10-50% relative humidity (RH) and 0.72 g g-1 at 34% RH. Molecular simulations and solid-state NMR identified liquid-like water, critical for harvesting applications, as the key contributor to the superior sorption performance of STA-16(Co). Scalable aqueous synthesis methods are developed, producing tens of grams of MOFs per batch without high-pressure equipment. A prototype device incorporating STA-12(Ni) demonstrated the feasibility of these materials for real-world water harvesting, showcasing their potential to address water scarcity in arid regions.

Covalent Organic Frameworks with Regulated Water Adsorption Sites for Efficient Cooling of Electronics

The excessive heat accumulation has been the greatest danger for chips to maintain the computing power. In this paper, a passive thermal management strategy for electronics cooling was developed based on the water vapor desorption process of the covalent organic frameworks (COFs). The precise regulation for the number of carbonyl group and the ratio of hydrophilicity and hydrophobicity within pore channels was achieved by water adsorption sites engineering. In particular, COF-THTA with abundant water adsorption sites exhibited highest water uptake and desorption energy, which facilitate efficient cooling of electronics. In proof-of-concept testing, COF-THTA coating (40×40 mm) provided a temperature drop of 7.5 °C in 25 minutes at a heating power of 937.5 W/m2, and remained stable after 10 intermittent heat cycles. Furthermore, the equivalent enthalpy of COF-THTA coating can reach up to 1136 J/gcoating. In real application scenarios, COF-THTA coating improved the performance of two real computing devices by 26.73 % and 22.61 %, respectively. This strategy based on COFs provides a new thinking for passive thermal management, exhibiting great potential in efficient cooling of electronics.

One-Step Ethylene Purification from Ternary Mixture through Adaptive Recognition Sites

One-step adsorptive purification of ethylene (C2H4) from ternary mixture comprising of acetylene (C2H2), ethylene (C2H4) and carbon dioxide (CO2) is a great challenge in the chemical industry. Herein, a microporous metal-organic framework (FJI-H38) has been reported, which possesses high-density electronegative O/N binding sites and appropriate pore size. Notably, at 0.01 bar and 298 K FJI-H38 shows excellent trapping capability for C2H2 (1.64 mmol/g) and CO2 (2.33 mmol/g), while the uptake of C2H4 is only 0.41 mmol/g, which endows FJI-H38 high C2H2/C2H4 and top-level CO2/C2H4 selectivity simultaneously. Polymer-grade C2H4 (≥99.95 %) with record-high productivity can be successfully obtained from ternary C2H2/CO2/C2H4 mixture in one step under various conditions. Even at 318 K, the separation performance has no obvious decrease. Such excellent separation performance is due to the adaptive recognition of C2H2 and CO2 by FJI-H38 through the synergistic effect of appropriate pore size and the match of electrostatic potentials, where C2H2 and CO2 can be stabilized by the O/N and aromatic ring sites.

Advancements of astaxanthin production in Haematococcus pluvialis: Update insight and way forward

The global market demand for natural astaxanthin (AXT) is growing rapidly owing to its potential human health benefits and diverse industry applications, driven by its safety, unique structure, and special function. Currently, the alga Haematococcus pluvialis (alternative name H. lacustris) has been considered as one of the best large-scale producers of natural AXT. However, the industry's further development faces two main challenges: the limited cultivation areas due to light-dependent AXT accumulation and the low AXT yield coupled with high production costs resulting from complex, time-consuming upstream biomass culture and downstream AXT extraction processes. Therefore, it is urgently to develop novel strategies to improve the AXT production in H. pluvialis to meet industrial demands, which makes its commercialization cost-effective. Although several strategies related to screening excellent target strains, optimizing culture condition for high biomass yield, elucidating the AXT biosynthetic pathway, and exploiting effective inducers for high AXT content have been applied to enhance the AXT production in H. pluvialis, there are still some unsolved and easily ignored perspectives. In this review, firstly, we summarize the structure and function of natural AXT focus on those from the algal H. pluvialis. Secondly, the latest findings regarding the AXT biosynthetic pathway including spatiotemporal specificity, transport, esterification, and storage are updated. Thirdly, we systematically assess enhancement strategies on AXT yield. Fourthly, the regulation mechanisms of AXT accumulation under various stresses are discussed. Finally, the integrated and systematic solutions for improving AXT production are proposed. This review not only fills the existing gap about the AXT accumulation, but also points the way forward for AXT production in H. pluvialis.

Encage the Carcinogens: A Metal-"Organic Cage" Framework for Efficient Polycyclic Aromatic Hydrocarbon Removal From Water

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and persistent organic pollutants in water. Their removal is highly challenging for existing generic and nonspecific adsorbents, creating an urgent need for tailored solutions. Herein, a metal-"organic cage" framework, MOF-CC-1, designed for the effective scavenging of PAHs from water is is introduced. This framework is constructed using a propeller-shaped cofacial organic cage (CC-1), equipped with three triazole pillars that coordinate with Ag(I) ions. The cationic MOF-CC-1 adopts a chiral (10,3)-a srs net structure, spontaneously resolving into homochiral crystals. Additionally, bulk homochirality is achieved through chirality induction using chiral counteranions. MOF-CC-1 uniquely encapsulates diverse PAH molecules within the cavities of CC-1, as confirmed by single-crystal X-ray diffraction, marking it as the first metal-"organic cage" framework with structural evidence of guest inclusion inside the organic cage linker. Further, MOF-CC-1 exhibits soft porosity, remaining nonporous to N₂ gas when compressed but expanding to encapsulate PAHs in solution. Moreover, MOF-CC-1 exhibits exceptional efficacy in scavenging ppb levels of PAHs from water. This work represents a significant advancement in utilizing organic cages as ligands toward MOF construction, paving the way for tailored adsorbents for PAH removal, and addressing a critical need for selective and efficient materials in environmental remediation.

Metal-Organic Framework-Assisted Atmospheric Water Harvesting Enables Cheap Clean Water Available in an Arid Climate: A Perspective

Extracting water directly from the atmosphere seems to be a perfect way to solve the water scarcity facing 2 billion people; however, traditional Atmospheric Water Harvesting (AWH) lacks the ability to adsorb water molecules in an arid climate. Porous materials are capable of assisting water adsorption; however, currently, only certain customizable Metal-Organic Frameworks (MOFs) are able to meet the standard of adsorbing water molecules at low humidity and releasing water at low temperatures at certain times that can realize assisted AWH's practical and energy-efficient use (Energy consumption < 5kWh/L-water). From this perspective, we offer a concise review of the advancements in enhanced AWH technologies, delve into the attributes of appropriate MOFs, and offer insights into the potential and future directions of MOFs-AWH. In conclusion, we underscore that that the development of designable MOFs holds the key to the widespread practical implementation of AWH, promising the availability of affordable clean water anywhere in the world.

An Ultramicroporous Physisorbent Sustained by a Trifecta of Directional Supramolecular Interactions

2D and 3D porous coordination networks (PCNs) as exemplified by metal-organic frameworks, MOFs, have garnered interest for their potential utility as sorbents for molecular separations and storage. The inherent modularity of PCNs has enabled the development of crystal engineering strategies for systematic fine-tuning of pore size and chemistry in families of related PCNs. The same cannot be said about one-dimensional (1D) coordination polymers, CPs, which are understudied with respect to porosity. Here, we report that permanent porosity is exhibited by the previously reported family of linear (L) 1D porous CPs, PCPs, of formula [M(bipy)(NO3)2(H2O)2]n (L-chn-1-M-NO3: M = Co, Ni; bipy = 4,4'-bipyridine). Their pore structure comprises 1D channels sustained by three types of directional interaction: coordination bonds; hydrogen bonds; offset π-π interactions. Heating L-chn-1-M-NO3 in vacuo or above 383 K resulted in removal of the aqua ligands and concomitant transformation to nonporous anhydrate phases ZZ-chn-1-Co-NO3 (ZZ = zigzag) and HT-Ni. Exposure of these anhydrate phases to ambient humidity resulted in regeneration of L-chn-1-M-NO3. That L-chn-1-M-NO3 exhibits permanent porosity was supported by CO2 and water sorption measurements, which afforded reversible type I and stepped (S-shaped) isotherm profiles, respectively, making this work the first demonstration of reversible water sorption in a 1D PCP. The water sorption properties are pertinent to atmospheric water harvesting: onset of uptake at ca. 12% relative humidity; activation required only mild heat or vacuum; relatively fast adsorption/desorption kinetics; performance retained over >100 adsorption/desorption cycles. We project water harvesting productivity of L-chn-1-M-NO3 of 3.3 L kg-1 d-1, on par with some leading MOF desiccants. DFT and Monte Carlo simulations provide insights into the structure of water molecules in the channels, provide their influence on the host framework, and provide a plausible argument for the experimental water vapor isotherms. This work demonstrates that easily scalable 1D PCPs, a potentially vast class of materials, can exhibit porous structures sustained by three types of directional supramolecular synthons and offer desirable water sorption properties.

Proton-Mediated Dynamic Nestling of DNA Payloads Within Size-Matched MOFs Nanochannels for Smart Intracellular Delivery

With sequence-programmable biological functions and excellent biocompatibility, synthetic functional DNA holds great promise for various biological applications. However, it remains a challenge to simultaneously retain their biological functions while protecting these fragile oligonucleotides from the degradation by nucleases abundant in biological circumstances. Herein, a smart delivery system for functional DNA payloads is developed based on proton-mediated dynamic nestling of cytosine-rich DNA moieties within the precisely size-matched nanochannels of highly crystalline metal-organic frameworks (MOFs): At neutral pH, cytosine-rich DNA strands exhibit a flexible single-stranded state and can be accommodated by MOFs nanochannels with a size of ca. 2.0 nm; while at acidic conditions, the protonation of cytosine-rich strands weakens their interaction with the nanochannels, and the tendency to form four-stranded structures drives these DNA strands out of the nanochannels. Results confirm the successful protection of DNA payloads from enzymatic hydrolysis by the MOFs nanochannels, and the delicate coupling of the endocytosis processes and the proton-responsive Cytosine-rich DNA/MOFs systems realized the efficient intracellular delivery of DNA payloads. Furthermore, with a complementary sequence to the telomere overhangs, direct imaging of telomeres and the nucleus is successfully achieved with the proton-mediated DNA/MOFs system.

Enhanced Hydrophilicity of DAAQ-TFP COFs via Sulfonate Modification for Air Water Harvesting in Arid Environment

The poor ability of covalent organic frameworks (COFs) based adsorbents at low relative humidity (RH) conditions limits their applications for air-water harvesting in arid environments. In the present work, the sulfonated COFs (DAAQ-TFP-SO3H@LiCl) composites are prepared through the functionalization of sulfonic acid and LiCl composite to improve its hydrophilicity. TheDAAQ-TFP-SO3H@LiCl composites exhibit a good adsorption performance, outperforming many other COF adsorbents developed so far. It can absorb 0.22 ± 0.005 g g-1 and 1.01 ± 0.027 g g-1 of water at room temperature under 20% RH and 90% RH, respectively while demonstrating good cyclic stability. Compared with the isotherm of the DAAQ-TFP, the introduction of the sulfonic acid group shifts the inflection point of the water isotherm toward low humidity, indicating that the sulfonic acid group effectively expends the working humidity range of the adsorbent and enables the effective water adsorption in an arid environment. Furthermore, the DAAQ-TFP-SO3H@LiCl composites display rapid kinetics during both the adsorption and desorption processes, reaching saturation within 60 min in the equilibrium adsorption test and completing desorption within 12 min at 50 °C. This innovative approach provides a new method for designing adsorbent materials with low energy input requirements and high daily water consumption capabilities.

Enhancement of Water Productivity and Energy Efficiency in Sorption-based Atmospheric Water Harvesting Systems: From Material, Component to System Level

To address the increasingly serious water scarcity across the world, sorption-based atmospheric water harvesting (SAWH) continues to attract attention among various water production methods, due to it being less dependent on climatic and geographical conditions. Water productivity and energy efficiency are the two most important evaluation indicators. Therefore, this review aims to comprehensively and systematically summarize and discuss the water productivity and energy efficiency enhancement methods for SAWH systems based on three levels, from material to component to system. First, the material level covers the characteristics, categories, and mechanisms of different sorbents. Second, the component level focuses on the sorbent bed, regeneration energy, and condenser. Third, the system level encompasses the system design, operation, and synergetic effect generation with other mechanisms. Specifically, the key and promising improvement methods are: synthesizing composite sorbents with high water uptake, fast sorption kinetics, and low regeneration energy (material level); improving thermal insulation between the sorbent bed and condenser, utilizing renewable energy or electrical heating for desorption and multistage design (component level); achieving continuous system operation with a desired number of sorbent beds or rotational structure, and integrating with Peltier cooling or passive radiative cooling technologies (system level). In addition, applications and challenges of SAWH systems are explored, followed by potential outlooks and future perspectives. Overall, it is expected that this review article can provide promising directions and guidelines for the design and operation of SAWH systems with the aim of achieving high water productivity and energy efficiency.

Hydrogel-embedded vertically aligned metal-organic framework nanosheet membrane for efficient water harvesting

Highly porous metal-organic framework (MOF) nanosheets have shown promising potential for efficient water sorption kinetics in atmospheric water harvesting (AWH) systems. However, the water uptake of single-component MOF absorbents remains limited due to their low water retention. To overcome this limitation, we present a strategy for fabricating vertically aligned MOF nanosheets on hydrogel membrane substrates (MOF-CT/PVA) to achieve ultrafast AWH with high water uptake. By employing directional growth of MOF nanosheets, we successfully create superhydrophilic MOF coating layer and pore channels for efficient water transportation to the crosslinked flexible hydrogel membrane. The designed composite water harvester exhibits ultrafast sorption kinetics, achieving 91.4% saturation within 15 min. Moreover, MOF-CT/PVA exhibits superior solar-driven water capture-release capacity even after 10 cycles of reuse. This construction approach significantly enhances the water vapor adsorption, offering a potential solution for the design of composite MOF-membrane harvesters to mitigate the freshwater crisis.

Recent Advances of Carbon Capture in Metal-Organic Frameworks: A Comprehensive Review

The excessive emission of greenhouse gases, which leads to global warming and alarms the world, has triggered a global campaign for carbon neutrality. Carbon capture and sequestration (CCS) technology has aroused wide research interest as a versatile emission mitigation technology. Metal-organic frameworks (MOFs), as a new class of high-performance adsorbents, hold great potential for CO2 capture from large point sources and ambient air due to their ultra-high specific surface area as well as pore structure. In recent years, MOFs have made great progress in the field of CO2 capture and separation, and have published a number of important results, which have greatly promoted the development of MOF materials for practical carbon capture applications. This review summarizes the most recent advanced research on MOF materials for carbon capture in various application scenarios over the past six years. The strategies for enhancing CO2 selective adsorption and separation of MOFs are described in detail, along with the development of MOF-based composites. Moreover, this review also systematically summarizes the highly concerned issues of MOF materials in practical applications of carbon capture. Finally, future research on CO2 capture by MOF materials is prospected.

Elimination of Trace Tetracycline with Alkyl Modified MIL-101 in Water

The overuse of antibiotics poses a serious threat to human health and ecosystems. Therefore, the development of high-performance antibiotic removal materials has attracted increasing attention. However, the adsorption and removal of trace amounts of antibiotics in aqueous systems still face significant challenges. Taking tetracycline (TC) as a representative antibiotic and based on its structural characteristics, a series of TC adsorbents are prepared by grafting alkyl groups to the framework of MIL-101(Cr). The adsorptive capacity of the modified materials for tetracycline markedly surpasses that of MIL-101(Cr), with MIL-101-dod achieving the best adsorption performance. MIL-101-dod demonstrated an outstanding ability to adsorb tetracycline at low concentrations, where a 5.0 mg sample of MIL-101-dod can reduce the concentration of a 90 mL 5 ppm tetracycline solution to below 1 ppb, significantly superior to other sorbents. XPS and IR tests indicate that MIL-101-dod has multiple weak interactions with tetracycline molecules, including C─H…O and C─H…π. This work provides theoretical and experimental support for the development of adsorbents for low-concentration antibiotics.

Recent advances in porous organic cages for energy applications

In recent years, the energy and environmental crises have attracted more and more attention. It is very important to develop new materials and technologies for energy storage and conversion. In particular, it is crucial to develop carriers that store energy or promote mass and electron transport. Emerging porous organic cages (POCs) are very suitable for this purpose because they have inherent advantages including structural designability, porosity, multifunction and post-synthetic modification. POC-based materials, such as pristine POCs, POC composites and POC derivatives also exhibit excellent energy-related properties. This latest perspective provides an overview of the progress of POC-based materials in energy storage and conversion applications, including photocatalysis, electrocatalysis (CO2RR, NO3RR, ORR, HER and OER), separation (gas separation and liquid separation), batteries (lithium-sulfur, lithium-ion and perovskite solar batteries) and proton conductivity, highlighting the unique advantages of POC-based materials in various forms. Finally, we summarize the current advances, challenges and further perspectives of POC-based materials in energy applications. This perspective will promote the design and synthesis of next-generation POC-based materials for energy applications.

Cu(II)-Organic Framework for Carboxylative Cyclization of Propargylic Amines with CO2

Effective CO2 transformations hold essential significance for carbon neutrality and sustainable energy development. Carboxylative cyclization of propargylic amines with CO2 serves as an atom-economic reaction to afford oxazolidinones, showing broad applications in organic synthesis and pharmaceutical fields. However, most catalysts involved noble metals, exhibited low efficiency, or required large amounts of base. Hence, it is imperative to explore alternative noble-metal-free catalysts in order to achieve efficient conversion while minimizing the use of additives. Herein, a novel nanopore-based Cu(II)-organic framework (1) based on a new imidazole carboxylic ligand was successfully constructed and exhibited excellent stability. Catalytic investigations revealed that the combination of 1 with 1,4-diaza[2.2.2]bicyclooctane (DABCO) efficiently catalyzed the carboxylative cyclization of propargylic amines with CO2, achieving turnover numbers of 142 based on the catalyst and 7.1 based on DABCO. 1 as a heterogeneous catalyst maintained high catalytic performance even after being reused at least 5 cycles, with its structure remaining stable. The strong activation of Cu(II) cluster nodes of catalyst 1 toward -NH- groups within organic substrates, as demonstrated by mechanism experiments, along with excellent CO2 adsorption performance and the presence of regular 1D channels, synergistically facilitates the reaction rate. This research presents the first instance of a Cu(II)-organic framework achieving this cyclization reaction, offering wide prospects for novel catalyst design and CO2 utilization.

Porous Calcium-Silicate-Hydrate as a Low-Cost Nano-Platform for Ultra-High CO2 Capture and Storage

CO2 capture and storage have been regarded as promising concepts to reduce anthropogenic CO2 emissions. However, the high cost, inferior adsorption capacity, and higher effective activation temperature of traditional sorbents limit their practical application in efficient CO2 capture. Here, a C-S-H@ZIF-8 (C-S-Z) sorbent is fabricated by in situ growth of the ZIF-8 shell on the C-S-H (calcium-silicate-hydrate) surface for ultra-high CO2 adsorption and storage. Among the C-S-Z, the outer ZIF-8 shell acts as a transport channel that promotes CO2 absorption toward the underlying C-S-H substrate for accelerated carbonation while preventing nitrogen and water from reaching the interior C-S-H. As a consequence, C-S-Z possesses the merits of ample pyrrolic nitrogen, porous structure, and ultra-high surface area (577.18 m2 g-1), that contribute to an ultra-high CO2 capture capacity, reaching 293.6 mg g-1. DFT calculations show a high CO2 adsorption energy and the mineral carbonation is dominant by the adsorption process. In particular, the advantages of the outstanding adsorption capacity, low cost, and high CO2 selectivity make this C-S-H-based sorbent hold great potential in the practical application for direct air CO2 capture and storage.

Interpenetrated In(III)-MOF with Multiple Recognition Sites for Single-Step Ethylene Purification

An interpenetrated indium(III) metal-organic framework (MOF), NTUniv-73, with a rarely reported tetrameric indium cluster is developed for streamlining ethylene purification from C2 gases. At 298 K, the adsorption capacities exhibited a complete reversal sequence of C2H6 > C2H2 > C2H4. Grand canonical Monte Carlo simulation indicated that the corners in a octahedral cage facilitated the C2H2/C2H4 separation, while the pocket-like aperture situated between adjacent octahedral cages allows for full contact of C2H6. Breakthrough experiments illustrated that NTUniv-73 could yield pure C2H4 in a single step with a productivity of 0.42 mmol g-1.

Electrochemical Anion Sensing Using Conductive Metal-Organic Framework Nanocrystals with Confined Pores

Anion sensing technology is motivated by the widespread and critical roles played by anions in biological systems and the environment. Electrochemical approaches comprise a major portion of this field but so far have relied on redox-active molecules appended to electrodes that often lack the ability to produce mixtures of distinct signatures from mixtures of different anions. Here, nanocrystalline films of the conductive metal-organic framework (MOF) Cr(1,2,3-triazolate)2 are used to differentiate anions based on size, which consequently affect the reversible oxidation of the MOF. During framework oxidation, the intercalation of larger charge-balancing anions (e.g., ClO4-, PF6-, and OTf-) gives rise to redox potentials shifted anodically by hundreds of mV due to the additional work of solvent reorganization and anion desolvation. Smaller anions (e.g., BF4-) may enter partially solvated, while larger ansions (e.g., OTf-) intercalate with complete desolvation. As a proof-of-concept, we leverage this "nanoconfinement" approach to report an electrochemical ClO4- sensor in aqueous media that is recyclable, reusable, and sensitive to sub-100-nM concentrations. Taken together, these results exemplify an unusual combination of distinct external versus internal surface chemistry in MOF nanocrystals and the interfacial chemistry they enable as a novel supramolecular approach for redox voltammetric anion sensing.

Direct Ethylene Purification from a Four-Component Gas Mixture by a Microporous MOF with Aromatic Pore Surface and Carboxylates

The single-step purification of ethylene (C2H4) from a mixture of carbon dioxide (CO2), acetylene (C2H2), ethylene (C2H4), and ethane (C2H6) was achieved through MOF Compound-1, where the aromatic pore surface and carboxylates selectively recognized C2H6 and CO2, respectively, resulting in a reversal of the adsorption orders for both gases (C2H6 > C2H4 and CO2 > C2H4). Breakthrough testing verified that the C2H4 purification ability could be enhanced 2.6 times after adding impure CO2. Grand Canonical Monte Carlo (GCMC) simulations demonstrate that there are interactions between CO2 and C2H6 molecules as well as between CO2 molecules themselves. These interactions contribute to the enhancement of the C2H4 purification ability upon the addition of CO2 and the increased adsorption of CO2.

Mining for Metal-Organic Systems: Chemistry Frontiers of Th-, U-, and Zr-Materials

The conceptual framework presented in this Perspective overviews the design principles of innovative thorium-based materials that could address urgent needs of the medicinal, nuclear energy, and waste remediation sectors from the lens of zirconium and uranium analogs. We survey the intersections of Zr, Th, and U chemistry with a focus on how the intrinsic behavior of each metal translates to broader material properties, including, but not limited to, structural and topological diversity, preferential metal-ligand binding, and reactivity. On the example of several classes of materials, including organometallic complexes, polyoxometalates, and the primary focus of this Perspective, metal-organic frameworks (MOFs), the design principles that govern the preparation of Zr-, Th-, and U-compounds, including oxophilicity, variation in oxidation states, and stable coordination environments have been considered. Further, we highlight how the impact of the mentioned variables may shift throughout the progression from discrete molecular systems to extended structures. We discuss the common assumption that zirconium-organic materials are typically considered a close analog of thorium-based congeners in areas such as material design and preparation. Through consideration of fundamental chemistry principles, we shed light on the relationships between Zr-, Th-, and U-based materials and highlight how a critical analysis of their distinct properties can be used to target a desired material performance. As a result, we provide a detailed understanding of Th-based materials chemistry by anchoring their fundamental properties between two well-studied reference points, zirconium- and uranium-containing analogs.

Covalent Organic Frameworks for Water Harvesting from Air

Despite approximately 70 % of the earth being covered by water, water shortage has emerged as an urgent social challenge. Sorbent-based atmospheric water harvesting stands out as a potent approach to alleviate the situation, particularly in arid regions. This method requires adsorbents with ample working capacity, rapid kinetics, low energy costs, and long-term stability under operating conditions. Covalent organic frameworks (COFs) are a novel class of crystalline porous materials and offer distinct advantages due to their high specific surface area, structural diversity, and robustness. These properties enable the rational design and customization of their water-harvesting capabilities. Herein, the basic concepts about the water sorption process within COFs, including the parameters that qualitatively or quantitatively describe their water isotherms and the mechanism are summarized. Then, the recent methods used to prepare COFs-based water harvesters are reviewed, emphasizing the structural diversity of COFs and presenting the common empirical understandings of these endeavors. Finally, challenges and research concepts are proposed to help develop next-generation COFs-based water harvesters.

Metal Hydrogen-Bonded Organic Frameworks as Open Lewis Acid Catalysts for Two Types of CO2 Transformations

Efficient and multiple CO2 utilization into high-value-added chemicals holds significant importance in carbon neutrality and industry production. However, most catalysis systems generally exhibit only one type of CO2 transformation with the efficiency to be improved. The restricted abundance of active catalytic sites or an inefficient utilization rate of these sites results in the constraint. Consequently, we designed and constructed two metal hydrogen-bonded organic frameworks (M-HOFs) {[M3(L3-)2(H2O)10]·2H2O}n (M = Co (1), Ni (2); L = 1-(4-carboxyphenyl)-1H-pyrazole-3,5-dicarboxylic acid) in this research. 1 and 2 are well-characterized, and both show excellent stability. The networks connected by multiple hydrogen bonds enhance the structural flexibility and create accessible Lewis acidic sites, promoting interactions between the substrates and catalytic centers. This enhancement facilitates efficient catalysis for two types of CO2 transformations, encompassing both cycloaddition reactions with epoxides and aziridines to afford cyclic carbonates and oxazolidinones. The catalytic activities (TON/TOF) are superior compared with those of most other catalysts. These heterogeneous catalysts still exhibited high performance after being reused several times. Mechanistic studies indicated intense interactions between the metal sites and substrates, demonstrating the reason for efficient catalysis. This marks the first instance on M-HOFs efficiently catalyzing two types of CO2 conversions, finding important significance for catalyst design and CO2 utilization.

Deep learning and big data mining for Metal-Organic frameworks with high performance for simultaneous desulfurization and carbon capture

Carbon capture and desulfurization of flue gases are crucial for the achievement of carbon neutrality and sustainable development. In this work, the "one-step" adsorption technology with high-performance metal-organic frameworks (MOFs) was proposed to simultaneously capture the SO2 and CO2. Four machine learning algorithms were used to predict the performance indicators (NCO2+SO2, SCO2+SO2/N2, and TSN) of MOFs, with Multi-Layer Perceptron Regression (MLPR) showing better performance (R2 = 0.93). To address sparse data of MOF chemical descriptors, we introduced the Deep Factorization Machines (DeepFM) model, outperforming MLPR with a higher R2 of 0.95. Then, sensitivity analysis was employed to find that the adsorption heat and porosity were the key factors for SO2 and CO2 capture performance of MOF, while the influence of open alkali metal sites also stood out. Furthermore, we established a kinetic model to batch simulate the breakthrough curves of TOP 1000 MOFs to investigate their dynamic adsorption separation performance for SO2/CO2/N2. The TOP 20 MOFs screened by the dynamic performance highly overlap with those screened by the static performance, with 76 % containing open alkali metal sites. This integrated approach of computational screening, machine learning, and dynamic analysis significantly advances the development of efficient MOF adsorbents for flue gas treatment.

Recent Progress on Porous Carbons for Carbon Capture

High emission of carbon dioxide (CO2) has caused CO2 levels to reach more than 400 ppm in air and led to a serious climate problem. In addition, in confined spaces such as submarines and aircraft, the CO2 concentration increase in the air caused by human respiration also affects human health. In order to protect the environment and human health, the search for high-performance adsorbents for carbon capture from high and low concentration gas is particularly important. Porous carbon materials, possessing the advantages of low cost and renewability, have set off a boom in the research of porous adsorbents, which have the opportunity to be utilized on a large scale for industrial carbon capture in the future. In this review, we summarize the recent research progress of porous carbons for carbon capture from flue gas and directly from air in the last five years, including activated carbon (AC), heteroatom-modified porous carbon, carbon molecular sieves (CMS), and other porous carbon materials, with a focus on the effects of temperature, water content, and gas flow rate of industrial flue gas on the performance of porous carbon adsorbents. We summarize the preparation strategies of various porous carbons and seek environmental friendly porous carbon materials preparation strategies under the premise of improving the CO2 adsorption capacity and selectivity of porous carbon adsorbents. Based on the effects of real industrial flue gas on adsorbents, we provide new ideas and evaluation methods for the development and preparation of porous carbon materials.

Flow Channel with Wrinkles and Calcium Sites in a Ca-MOF for Direct One-Step Ethylene Purification from C2 Gases and MTO Products Separation

The strategy of flow channel with wrinkles and calcium sites for single-step C2H4 purification from C2 gases and methanol-to-olefins (MTO) products separation was realized in FJI-Y9. The adsorption amounts showed a total reversal order of C3H6 > C2H6 > C2H2 > C2H4 at 298 K. Modeling indicated that the wrinkles and Ca2+ facilitated the full contact of C3H6 and C2H6. Breakthrough experiments illustrated that FJI-Y9 could yield pure C2H4 in a single step with a productivity of 0.78 mmol g-1. In a lone adsorption/desorption cycle for MTO product separation, the productivities of C3H6 and C2H4 were 1.96 and 1.29 mol g-1, standing as the highest recorded values.

Designed Synthesis of Fe/Zr Bimetallic Organic Framework to Enhance the Selective Conversion of H2S to Sulfur

The development of stable and effective catalysts to convert toxic H2S into high value-added sulfur is essential for production safety and environmental protection. However, the inherent defects of traditional iron- and zirconium-based catalysts, such as poor activity, high oxygen consumption, and low sulfur selectivity, limit their further developments and applications. Herein, the Fe-Zr bimetallic organic framework FeUIO-66(x) with different cubic morphologies was synthesized via a facile solvothermal method. The results indicate that the introduction of Fe not only increases the specific surface area and weak L-sites of the catalyst without changing its crystal structure, which provides enough reaction space and more active sites for the adsorption and activation of H2S, but also reduces the activation energy of the reaction, significantly promoting the selective oxidation of H2S. As a result, the as-obtained FeUIO-66(1) catalyst exhibits the highest desulfurization activity and superior durability and water resistance stability, and its H2S conversion and sulfur selectivity within 50 h are 100 and 88%, respectively. More importantly, the structure of the catalyst after the desulfurization reaction is consistent with that of the fresh counterpart. The study offers new insights into the development of effective and stable bimetallic catalysts to eliminate H2S and recycle sulfur.

Pentazolate Anion: A Rare and Preferred Five-Membered Ligand for Constructing Pentasil-Zeolite Topology Architectures

As the fourth full-nitrogen structure, the pentazolate anion (cyclo-N5 - ) was highly coveted for decades. In 2017, the first air-stable non-metal pentazolate salt, (N5 )6 (H3 O)3 (NH4 )4 Cl, was obtained, representing a milestone in this field. As the latest member of the azole family, cyclo-N5 - is comprised of five nitrogen atoms. Although significant attention has been paid to the potential of cyclo-N5 - as an energetic material, its poor thermostability hinders any practical application. However, the unique ring structure and multiple coordination capability of cyclo-N5 - provide a platform for the fabrication of various structures, among which pentasil-zeolite topologies are the most intriguing. In addition, the introduction of structure-directing auxiliaries enables the self-assembly of diverse topological architectures, potentially imparting cyclo-N5 - with the potential to impact wide-ranging areas of coordination chemistry and topology. In this minireview, different pentasil-zeolite topologies based on metal-pentazolate frameworks are evaluated. To date, three zeolitic and zeolite-like topologies have been reported, namely the melanophlogite (MEP), chibaite (MTN), and unj topologies. The MEP topology consists of two nanocages, Na20 N60 and Na24 N60 , whereas the MTN topology contains Na20 N60 and Na28 N80 nanocages. Furthermore, the unj topology features multiple homochiral channels consisting of two helical chains. Various possible strategies for obtaining additional pentasil-zeolite topologies are also discussed.

Carbonyl-Supported Coordination in Imidazolates: A Platform for Designing Porous Nickel-Based ZIFs as Heterogeneous Catalysts

Zeolitic imidazolate frameworks (ZIFs) are a subclass of metal-organic framework that have attracted considerable attention as potential functional materials due to their high chemical stability and ease of synthesis. ZIFs are usually composed of zinc ions coordinated with imidazole linkers, with some other transition metals, such as Cu(II) and Co(II), also showing potential as ZIF-forming cations. Despite the importance of nickel in catalysis, no Ni-based ZIF with permanent porosity is yet reported. It is found that the presence and arrangement of the carbonyl functional groups on the imidazole linker play a crucial role in completing the preferred octahedral coordination of nickel, revealing a promising platform for the rational design of Ni-based ZIFs for a wide range of catalytic applications. Herein, the synthesis of the first Ni-based ZIFs is reported and their high potential as heterogeneous catalysts for Suzuki-Miyaura cross-coupling C─C bond forming reactions is demonstrated.

Water-stable metal-organic frameworks (MOFs): rational construction and carbon dioxide capture

Metal-organic frameworks (MOFs) are considered to be a promising porous material due to their excellent porosity and chemical tailorability. However, due to the relatively weak strength of coordination bonds, the stability (e.g., water stability) of MOFs is usually poor, which severely inhibits their practical applications. To prepare water-stable MOFs, several important strategies such as increasing the bonding strength of building units and introducing hydrophobic units have been proposed, and many MOFs with excellent water stability have been prepared. Carbon dioxide not only causes a range of climate and health problems but also is a by-product of some important chemicals (e.g., natural gas). Due to their excellent adsorption performances, MOFs are considered as a promising adsorbent that can capture carbon dioxide efficiently and energetically, and many water-stable MOFs have been used to capture carbon dioxide in various scenarios, including flue gas decarbonization, direct air capture, and purified crude natural gas. In this review, we first introduce the design and synthesis of water-stable MOFs and then describe their applications in carbon dioxide capture, and finally provide some personal comments on the challenges facing these areas.

Flow Channel with Recognition Corners in a Stable La-MOF for One-Step Ethylene Production

Single-step ethylene (C2H4) production from acetylene (C2H2), ethylene (C2H4), and ethane (C2H6) mixtures was realized via the strategy of a flow channel with recognition corners in MOF NTUniv-64. Both the uptake amounts and the enthalpy of adsorption (Qst) showed the same order of C2H2 > C2H6 > C2H4. Breakthrough testing also verified the above data and the C2H4 purification ability. Grand Canonical Monte Carlo (GCMC) simulations indicated that uneven corners could precisely detain C2H2 and C2H6, in which the C-H···π interaction distance between C2H2 (2.84 Å) and C2H6 (3.03 Å) and the framework was shorter than that of C2H4 (3.85 Å).

Fine Tuning Metal-Organic Frameworks with Halogen Functional Groups for Ethylene Purification

One-step C2H4 purification from a mixture of C2H2/C2H4/C2H6 could be achieved by metal-organic framework (MOF) NTUniv-70 with an F-functional group. The selectivities of C2H4/C2H6 and C2H4/C2H2 of NTUnvi-70 based on ideal adsorbed solution theory were at least twice that of the original MOF platform, which was in line with the enthalpy of adsorption (Qst) and breakthrough testing. Grand canonical Monte Carlo simulations indicated that the C-H···F interactions played an important role in enhanced C2H4/C2H6 and C2H4/C2H2 adsorption selectivities.

Shaping the Water-Harvesting Behavior of Metal-Organic Frameworks Aided by Fine-Tuned GPT Models

We construct a data set of metal-organic framework (MOF) linkers and employ a fine-tuned GPT assistant to propose MOF linker designs by mutating and modifying the existing linker structures. This strategy allows the GPT model to learn the intricate language of chemistry in molecular representations, thereby achieving an enhanced accuracy in generating linker structures compared with its base models. Aiming to highlight the significance of linker design strategies in advancing the discovery of water-harvesting MOFs, we conducted a systematic MOF variant expansion upon state-of-the-art MOF-303 utilizing a multidimensional approach that integrates linker extension with multivariate tuning strategies. We synthesized a series of isoreticular aluminum MOFs, termed Long-Arm MOFs (LAMOF-1 to LAMOF-10), featuring linkers that bear various combinations of heteroatoms in their five-membered ring moiety, replacing pyrazole with either thiophene, furan, or thiazole rings or a combination of two. Beyond their consistent and robust architecture, as demonstrated by permanent porosity and thermal stability, the LAMOF series offers a generalizable synthesis strategy. Importantly, these 10 LAMOFs establish new benchmarks for water uptake (up to 0.64 g g-1) and operational humidity ranges (between 13 and 53%), thereby expanding the diversity of water-harvesting MOFs.

Expanding MOF with Unexpanded Channel via Ketone Decorated Ligand for Ethylene Purification and Stability Enhancement

The concept of an expanding MOF with unexpanded channel size was realized in MOF NTUniv-61 by the utilization of a ketone-functional-group-decorated semirigid ligand and pillar-layer platform. After this unusual expansion, the preferential C2H6 adsorption was preserved via the unchanged pore size, and the functional group was inserted into the MOF. Interestingly, the C2H2 uptake ability, C2H4 selective adsorption ability, and structural stability were obviously enhanced due to the incorporation of the ketone functional group, which were further verified by isosteric heats of adsorption (Qst), GCMC modeling, and breakthrough experiments.

Creating an Ethane Trap in a Ketone-Decorated MOF for One-Step Ethylene Separation from C2 Hydrocarbons

One-step C2H4 purification from a mixture of C2H2/C2H4/C2H6 by physical adsorption separation was realized via creating an ethane trap in MOF NTUniv-63 by the utilization of a ketone-decorated semirigid ligand, which has further been verified by the breakthrough experiment, isosteric heats of adsorption (Qst), and Grand Canonical Monte Carlo (GCMC) modeling.

Positional Isomers of Covalent Organic Frameworks for Indoor Humidity Regulation

Humidity is one of the most important indicators affecting human health. Here, a pair of covalent organic frameworks (COFs) of positional isomers (p-COF and o-COF) for indoor humidity regulation is reported. Although p-COF and o-COF have the same sql topology and pore size, they exhibit different water adsorption behaviors due to the subtle differences in water adsorption sites. Particularly, o-COF exhibits a steep adsorption isotherm in the range of 45-65% RH with a hysteresis loop, which is perfectly suitable for indoor humidity regulation. In the laboratory experiment, when the humidity of the external environment is 20-75% RH, o-COF can control the humidity of the room in the range of 45-60% RH. o-COF has shown great potential as a dual humidification/dehumidification adsorbent for indoor humidity regulation.

Coordination Polymers from an Amino-Functionalized Terphenyl-Tetracarboxylate Linker: Structural Multiplicity and Catalytic Properties

An amino-functionalized terphenyl-tetracarboxylic acid, 2'-amino-[1,1':4',1″-terphenyl]-3,3″,5,5″-tetracarboxylic acid (H4tpta), was used as an adaptable linker to synthesize, under hydrothermal conditions, eight coordination polymers (CPs). The obtained products were formulated as [Co(μ6-H2tpta)]n (1), [Co(μ3-H2tpta)(2,2'-bipy)]n (2), [M3(μ6-Htpta)2(2,2'-bipy)2]n (M = Mn (3), Cd (4)), [Ni2(μ4-tpta)(phen)2(H2O)4]n (5), [Zn2(μ6-tpta)(phen)2]n (6), {[Zn2(μ6-tpta)(μ-4,4'-bipy)]·H2O}n (7), and [Zn2(μ6-tpta)(μ-H2biim)(H2O)2]n (8), wherein 2,2'-bipyridine (2,2'-bipy), 4,4'-bipyridine (4,4'-bipy), 1,10-phenanthroline (phen), or 2,2'-biimidazole (H2biim) are present as additional stabilizing ligands. The structural types of 1-8 vary from one-dimensional (1D) (2, 5) and two-dimensional (2D) (3, 4, 6) CPs to three-dimensional (3D) metal-organic frameworks (MOFs) (1, 7, and 8) with a diversity of topologies. The products 1-8 were investigated as catalysts in the Knoevenagel condensation involving aldehydes and active methylene derivatives (malononitrile, ethyl cyanoacetate, or tert-butyl cyanoacetate), leading to high condensation product yields (up to 99%) under optimized conditions. Various reaction conditions, substrate scope, and catalyst recycling were investigated. This work broadens the application of H4tpta as a versatile tetracarboxylate linker for the generation of diverse CPs/MOFs.

Enhanced atmospheric water harvesting efficiency through green-synthesized MOF-801: a comparative study with solvothermal synthesis

Adsorption-based atmospheric water harvesting has emerged as a compelling solution in response to growing global water demand. In this context, Metal-organic frameworks (MOFs) have garnered considerable interest due to their unique structure and intrinsic porosity. Here, MOF 801 was synthesized using two different methods: solvothermal and green room temperature synthesis. Comprehensive characterization indicated the formation of MOF-801 with high phase purity, small crystallite size, and excellent thermal stability. Nitrogen adsorption-desorption analysis revealed that green-synthesized MOF-801 possessed an 89% higher specific surface area than its solvothermal-synthesized counterpart. Both adsorbents required activation at a minimum temperature of 90 °C for optimal adsorption performance. Additionally, green-synthesized MOF-801 demonstrated superior adsorption performance compared to solvothermal-synthesized MOF-801, attributed to its small crystal size (around 66 nm), more hydrophilic functional groups, greater specific surface area (691.05 m2/g), and the possibility of having a higher quantity of defects. The maximum water adsorption capacity in green-synthesized MOF-801 was observed at 25 °C and 80% relative humidity, with a value of 41.1 g/100 g, a 12% improvement over the solvothermal-synthesized MOF-801. Remarkably, even at a 30% humidity level, green-synthesized MOF-801 displayed a considerable adsorption capacity of 31.5 g/100 g. Importantly, MOF-801 exhibited long-term effectiveness in multiple adsorption cycles without substantial efficiency decline.

Ca-MOF-Derived Porous Sorbents for High-Yield Solar-Driven Atmosphere Water Harvesting

The development of high-yield, metal-organic framework (MOF)-based water harvesters in arid areas remains challenging due to the absence of effective strategies for enhancing water sorption capacity and kinetics. Herein, we presented a novel strategy for in situ fabrication of calcium chloride (CaCl2) decorated MOF-derived porous sorbents (PCC-42) through pyrolysis Ca-MOF and subsequently hydrochloric acid (HCl) vapor treatment process. The resulting PCC-42 sorbents exhibited a high water adsorption capacity of 3.04 g g-1 at 100% relative humidity (RH), outstanding photothermal performance, and rapid water uptake-release kinetics, surpassing most reported MOFs adsorbents. At 20, 30, 40, and 50% RH, PCC-42 demonstrated water uptake capacity of 0.45, 0.59, 0.76, and 0.9 g g-1, which represented an increase of 421 and 940% (at 20% RH) and 333 and 351% (at 30% RH) compared to Ca-MOF and CaCl2·2H2O, respectively. Approximately 80% of the adsorbed water in PCC-42 could be released under one sun within 50 min. Indoor water harvesting experiments demonstrated that PCC-42 is a promising adsorbent for various humidity environments. Additionally, outdoor solar-driven atmospheric water harvesting (AWH) tests revealed a high daily water production of 1.13 L/kgadsorbent under typical arid conditions (30-60% RH). The proposed strategy helps the design of high-performance adsorbents for solar-driven AWH in arid environments.

Enzyme‐Encapsulated Protein Trap Engineered Metal–Organic Framework‐Derived Biomineral Probes for Non‐Invasive Prostate Cancer Surveillance

A paper‐based naked‐eye recognition assay with enzyme‐encapsulated protein engineered metal–organic framework‐derived biominerals is developed for direct quantification of sarcosine in urine samples for screening of prostate cancer individuals. The detection strategy stems from the successful construction of a cascade response model, which involves the introduction of a cascade enzymatic catalytic reaction on Pt nanoparticles (NPs)‐loaded porous CeO2 by integrating a sarcosine oxidase as a special recognition unit and a chromogenic substrate as a signal molecule reporter. Pt NPs‐loaded CeO2 is subjected to a one‐step thermal treatment based on multilayered mesoporous Ce‐based metal–organic framework, and the calcined CeO2 exhibits the same distinct porous graded structure. Importantly, introduction of Pt NPs sharply enhances the peroxidase‐like activity of CeO2, which is considered to be caused by the difference in the adsorption behavior of hydrogen peroxide on the CeO2 surface and Pt/CeO2 obtained by density functional theory calculations. On the basis of this, the probe is used on a mass‐producible paper‐based working platform and 3D‐printed device to specifically screen for minor differences in sarcosine between urine samples from cancer patients and normal individuals. Enzyme‐assisted cascade catalytic reaction can be extended by replacing different recognition units for multiple analytes.

Fine-Tuning MOFs with Amino Group for One-Step Ethylene Purification from the C2 Hydrocarbon Mixture

Due to the similar kinetic diameters of C₂H₂, C₂H₄, and C₂H₆, one-step purification of C₂H₄ from a ternary C₂H₂/C₂H₄/C₂H₆ mixture by adsorption separation is still a challenge. Based on a C₂H₆-trapping platform and crystal engineering strategy, the N atom and amino group were introduced into NTUniv-58 and NTUniv-59, respectively. Gas adsorption testing of NTUniv-58 showed that both the C₂H₂ and C₂H₄ uptake capacities and the C₂H₂/C₂H₄ separation ability were boosted compared with the original platform. However, the C₂H₄ uptake value exceeds the C₂H₆ adsorption data. For NTUniv-59, the C₂H₂ uptake at low pressure increased and the C₂H₄ uptake decreased; thus, the C₂H₂/C₂H₄ selectivity was enhanced and the one-step purification of C₂H₄ from a ternary C₂H₂/C₂H₄/C₂H₆ mixture was realized, which was supported by the enthalpy of adsorption (Q_st) and breakthrough testing. Grand canonical monte carlo (GCMC) simulation indicated that the preference for C₂H₂ over C₂H₄ originates from multiple hydrogen-bonding interactions between amino groups and C₂H₂ molecules.