This work reports the design and synthesis of a novel imine-linked 2D covalent organic framework (COF), TPDA-BiPy-COF, constructed from [3,3 '-bipyridine]-6,6 '-dicarboxaldehyde (3,3 '-BiPy) as an electron acceptor and tetrakis(4-aminophenyl)-1,4-phenylenediamine (TPDA) as a donor. The COF features pyridylimine linkages, i.e., Nimine-Ni-Nbipyridine, with active nitrogen sites that facilitate proton reduction to hydrogen. To improve photocatalytic hydrogen evolution performance, Ni(II) centers were introduced via post-synthetic metalation, forming TPDA-BiPy@NiX2 COF (X = Cl, Br). The coordination of Ni(II) with the imine and bipyridine nitrogen atoms enhanced framework planarity and conjugation, thereby boosting photocatalytic activity. Notably, TPDA-BiPy@Ni(II) COF achieved an excellent hydrogen evolution rate of 34.13 mmol g-1 h-1 under visible light, without requiring a cocatalyst. Furthermore, the metallaphotoredox activity of TPDA-BiPy@Ni (II) displayed its promise for photocatalyzed C-S cross-coupling reaction. This dual-functional catalyst highlights the advantage of incorporating nickel into COFs, offering a cost-effective and sustainable alternative to noble-metal-based systems for photocatalysis and synthetic transformations.

The global energy supply still largely relies on fossil fuels, whose combustion releases significant amounts of carbon dioxide (CO2), the primary anthropogenic greenhouse gas linked to climate change. Adsorption on solid porous materials offers a promising alternative to conventional amine-based systems for CO2 capture from industrial flue gases. While various materials, including zeolites and metal-organic frameworks (MOFs), have been extensively studied for high-concentration CO2 streams, post-combustion capture at low concentrations (below 5% CO2) under realistic conditions with water vapor remains poorly explored. Material selection requires balancing CO2 adsorption capacity against water affinity, as strong hydrophilicity deteriorates regeneration efficiency. The challenge is to identify scalable, environmentally friendly materials that maintain high CO2 selectivity under realistic flue gas conditions containing both low CO2 concentrations and significant water vapor. Here, we show that CALF-20, a scalable MOF, exhibits superior CO2 adsorption selectivity and regenerability compared to other tested materials, both in dry and humid conditions. Under dynamic breakthrough conditions using 2.5% CO2 and 50% relative humidity, CALF-20 maintained a high CO2 uptake (1.49 mmol g-1) consistent with static isotherm data, and demonstrated complete regenerability at 80 °C without loss of performance over multiple cycles. These results directly contrast with hydrophilic zeolites, which, despite high raw CO2 capacities, are unsuitable under realistic, humid flue gas. Our results under industrially relevant post-combustion conditions demonstrate that low water affinity combined with moderate CO2 capacity outperforms high-capacity hydrophilic materials. This approach represents an effective pathway for CO2 capture under realistic conditions and provides valuable insights for the development of selective, robust, and scalable CO2 adsorbents. Such developments are expected to contribute significantly to reducing atmospheric CO2 emissions and addressing climate change mitigation targets in the coming years.

Accessing metal-organic frameworks (MOFs) with wide mesopores or specific topologies sometimes requires the use of an additional ligand, termed centring structure-directing agent (cSDA), which does not alter the targeted framework's periodicity. Here we report a general strategy to remove cSDAs post-synthetically, in a single-crystal to single-crystal fashion, enabling deliberate topology transformation often associated with substantial porosity enhancement. Such window opening can be achieved through two distinct routes. The first approach, guided by Pearson's hard and soft acids and bases (HSAB) principle, uses acid treatment to release cSDAs from robust frameworks, yielding pore volumes for Cr-MOFs of up to 3.6 cm3 g-1. The second, milder approach uses imidazole to selectively substitute cSDAs in MOFs within minutes. This strategy is applicable across various topologies (sod, nia-d and pop), confirming that cSDAs act as temporary architectural elements essential for framework formation and can be removed on demand. This work expands the scope of reticular chemistry by introducing another level of modularity.

Among the rich chemical and structural diversity of metal-organic frameworks (MOFs), those based on trivalent chromium (Cr(III)-MOFs) have attracted significant interest due to their typically high stability. However, their synthesis as highly crystalline materials remains challenging due to chromium's relative inertness, ability to adopt multiple oxidation states, and intricate electronic interactions with ligands. This study presents an innovative transmetalation approach from cobalt- and indium-based MOFs, expanding beyond the previously reported routes, mostly limited to iron-based MOF precursors. Moreover, the transmetalation can be performed on cations with varied accessibility in clusters with diverse connectivity (6 to 9). By expanding the library of possible metal precursors, we additionally overcome some limitations encountered with the traditional iron-based MOFs while increasing the structural diversity of highly porous Cr-MOFs. Specifically, Co-sod-ZMOF-307 and In-soc-MOF-1, when transformed to their chromium analogs, exhibit significantly enhanced stability and porosity compared to their initial as-synthesized forms. Cr-soc-MOF-1 (from In), for instance, shows a substantial increase in porosity, reaching 1.9 cm3/g, with a BET of 5668 m2/g, while Cr-sod-ZMOF-307 (from In) stands as one of the most porous Cr-MOFs reported, with pore volume reaching 2.4 cm3/g.

2D conjugated polymers (2D-CPs) are currently attracting substantial attention as host materials in electrochemical energy storage. They show some intriguing properties, such as high conductivity (by elevating the conjugated degree), adjustable redox activity (by controlling the monomers), and stable skeleton structure (low solubility in electrolytes). Herein, two aza-based 2D-CPs with different conjugation degrees are designed and developed for pseudocapacitive proton storage. The detailed electrochemical analysis shows that the highly conjugated 2D-CP (2D-HCP) demonstrates an inferior performance compared to partially conjugated 2D-CP (2D-PCP), especially in terms of the high-rate performance. Though combining various in-situ/ex-situ spectroscopy analyses and theoretical simulation, the reason behind this performance is revealed and is associated with the different solid-state proton diffusion kinetics in these two 2D-CPs. We believe this new understanding can be leveraged to design and develop more suitable 2D-CPs for electrochemical energy storage. (c) 2024 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The assembly of ultra-complex structures from simple building units remains a long-term challenge in chemistry. Using small molecular building blocks (MBBs) in a mixed-ligand approach permitted the assembly of unprecedented metal-organic frameworks (MOFs), M-kum-MOF-1 (M = Y, Tb), exhibiting extra-large mesoporous cavities with small access windows. The ultra-complex cage of M-kum-MOF-1 consists of 240 vertices bridged by 432 edges, leading to a 194 faces-containing tile. This tile exhibits more faces than in any periodic structures (zeolites, MOFs, metal-organic polyhedra [MOPs], etc.) known to date. M-kum-MOF-1 not only possess zeolitic features (anionic framework), but they also contain an underlying wse zeolitic topology, which is observed for the first time.

Here, we report the first utilization of covalent organic frameworks (COFs) in optical wireless communication (OWC) applications. In the solid form, aggregation-induced emission (AIE) luminogen often shows promising emissive characteristics that augment radiative decays and improve fluorescence. We have synthesized an AIE-COF through the Knoevenagel condensation reaction by taking advantage of the ability to carefully design and alter the COF structure by integrating an AIE luminogen with linear building blocks. The synthesized AIE-COF exhibited a high solid-state photoluminescence quantum yield (∼39%) and a short photoluminescence lifetime (∼1 ns), crucial for achieving modulation bandwidth for high-speed OWC applications. For comparison, we constructed an aggregation-caused quenching based COF, showing a similar lifetime but almost insignificant quantum yield. The orthogonal frequency-division multiplexing modulation strategy employed by the AIE-COF demonstrates remarkable high-rate data transmission, with a wide -3 dB modulation bandwidth of nearly 200 MHz and achieving high net data rates of 825 Mb/s, outperforming traditional materials. These results open new avenues for the ability to design and finetune new COF materials for their utilization as color converters in developing cutting-edge OWC components, enabling faster and more efficient data transfer.

Aqueous ammonium ion batteries have garnered significant research interest due to their safety and sustainability advantages. However, the development of reliable ammonium-based full batteries with consistent electrochemical performance, particularly in terms of cycling stability, remains challenging. A primary issue stems from the lack of suitable anode materials, as the relatively large NH4 + ions can cause structural damage and material dissolution during battery operation. To address this challenge, an Aza-based covalent organic framework (COF) material is introduced as an anode for aqueous ammonium ion batteries. This material exhibits superior ammonium storage capabilities compared to existing anode materials. It operates effectively within a negative potential range of 0.3 to‒1.0 V versus SCE, achieves high capacity even at elevated current densities (≈74 mAh g-1 at 10 A g-1), and demonstrates exceptional stability, retaining a capacity over 20 000 cycles at 1.0 A g-1. Furthermore, by pairing this COF anode with a Prussian blue cathode, an ammonium rocking-chair full battery is developedd that maintains 89% capacity over 20 000 cycles at 1.0 A g-1, surpassing all previously reported ammonium ion full batteries. This study offers insights for the design of future anodes for ammonium ion batteries and holds promise for high-energy storage solutions.

Metal-organic frameworks (MOFs) incorporating open metal sites (OMS) have been identified as promising sorbents for many societally relevant-adsorption applications including CO$_2$ capture, natural gas purification and H$_2$ storage. It is critical to derive generic interatomic potential to achieve accurate and effective evaluation of MOFs for H$_2$ adsorption. On this path, as a proof-of-concept, the Al-soc-MOF containing Al-OMS, previously envisaged as a potential candidate for H$_2$ adsorption, was selected and a machine learning potential (MLP) was derived from a dataset initially generated by ab-initio molecular dynamics (AIMD) simulations. This MLP was further implemented in MD simulations to explore the binding modes of H$_2$ as well as its temperature dependence distribution in the MOFs pores from 10K to 90K. MLP-Grand Canonical Monte Carlo (GCMC) simulations were further performed to predict the H$_2$ sorption isotherm of Al-soc-MOF at 77K that was further confirmed by gravimetric sorption measurements. As a further step, MLP-based MD simulations were conducted to anticipate the kinetics of H$_2$ in this MOF. This work delivers the first MLP able to describe accurately the interactions between the challenging H$_2$ guest molecule and MOFs containing OMS. This innovative strategy applied to one of the most complex molecules owing to its highly polarizable nature alongside its quantum-mechanical effects that are only accurately described by quantum calculations, paves the way towards a more systematic accurate and efficient in silico assessment of the MOFs containing OMS for H$_2$ adsorption and beyond to the low-pressure capture/sensing of diverse molecules.

Metal-Organic Frameworks can be grafted with amines by coordination to metal vacancies to create amine-appended solid adsorbents, which are being considered as an alternative to using aqueous amine solutions for CO 2 capture. In this study, we propose an alternative mechanism that does not rely on the use of neutral metal vacancies as binding sites but is enabled by the structural adaptability of heterobimetallic Ti 2 Ca 2 clusters. The combination of hard (Ti 4+ ) and soft (Ca 2+ ) metal centers in the inorganic nodes of the framework enables MUV-10 to adapt its pore windows to the presence of triethylenetetramine molecules. This dynamic cluster response facilitates the translocation and binding of tetraamine inside the microporous cavities to enable the formation of bis-coordinate adducts that are stable in water. The extension of this grafting concept from MUV-10 to larger cavities not restrictive to CO 2 diffusion will complement other strategies available for the design of molecular sorbents for decarbonization applications.

Rational design of intricate multicomponent reticular structures is often hindered by the lack of suitable blueprint nets. We established the merged-net approach, proffering optimal balance between designability and complexity, as a systematic solution for the rational assembly of multicomponent structures. In this work, by methodically mapping node-net relationships among 53 basic edge-transitive nets, we conceived a signature net map to identify merging net pairs, resulting in the enumeration of 53 merged nets. We developed a practical design algorithm and proposed more than 100 multicomponent metal-organic framework platforms. The effectiveness of this approach is commended by the successful synthesis of four classes of materials, which is based on merging three-periodic nets with the four possible net periodicities. The construction of multicomponent materials based on derived nets of merged nets highlights the potential of the merged-net approach in accelerating the discovery of intricate reticular materials.

Building blocks with low connectivity and no embedded directionality are prone to polymorphism, as demonstrated by the diversity of 4-connected zeolitic nets (>250). As a result, their deployment for design in reticular and isoreticular chemistries remains a challenge. However, the ability to control geometrical peculiarities offers potential to deviate from the assembly of default structures. Here we report the face-directed assembly of >20 isoreticular zeolite-like metal–organic frameworks (ZMOFs) by using polytopic expanding and tightening centring structure-directing agents (cSDAs). The cSDAs are selected with the appropriate geometrical coding information to alter and control the orientation of adjacent supermolecular building blocks. The ZMOFs have an underlying sodalite ( sod ) topology that is remarkably suited for the rational assembly of multinary materials. In addition to a variety of metal cations (In, Fe, Co and Ni), a diverse range of cSDAs (di-, tri-, tetra-, hexa-, pyridyl or imidazole) are used and combined. Our approach enables isoreticular possibilities at both extremities of the porous materials spectrum: In- sod -ZMOF-102 exhibits small pore aperture suitable for efficient separation, while Fe- sod -ZMOF-320 with 48-Å-wide mesopores exhibits high hydrogen uptake, methane storage working capacity and a high gravimetric working capacity for oxygen.

Metal--organic frameworks (MOFs) are a rapidly growing class of materials that offer great promise in various applications. However, the synthesis remains challenging: for example, a range of crystal structures can often be accessed from the same building blocks, which complicates the phase selectivity. Likewise, the high sensitivity to slight changes in synthesis conditions may cause reproducibility issues. This is crucial, as it hampers the research and commercialisation of affected MOFs. Here, we present the first-ever interlaboratory study of the synthetic reproducibility of two Zr--porphyrin MOFs, PCN-222 and PCN-224, to investigate the scope of this problem. For PCN-222, only one sample out of ten was phase pure and of the correct symmetry, while for PCN-224, three were phase pure, although none of these show the spatial linker order characteristic of PCN-224. Instead, these samples resemble dPCN-224 (disordered PCN-224), which was recently reported by us. The variability in thermal behaviour, defect content, and BET surface area of the synthesised samples are also studied. Our results have important ramifications for field of metal--organic frameworks and their crystallisation, by highlighting the synthetic challenges associated with a multi-variable synthesis space and flat energy landscapes characteristic of MOFs.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A one-stone, two-bird method to integrate the soft porosity and electrical properties of distinct metal-organic frameworks (MOFs) into a single material involves the design of conductive-on-insulating MOF (cMOF-on-iMOF) heterostructures that allow for direct electrical control. Herein, we report the synthesis of cMOF-on-iMOF heterostructures using a seeded layer-by-layer method, in which the sorptive iMOF core is combined with chemiresistive cMOF shells. The resulting cMOF-on-iMOF heterostructures exhibit enhanced selective sorption of CO2 compared to the pristine iMOF (298 K, 1 bar, S CO2/H2 ${{_{{\rm CO}{_{2}}/{\rm H}{_{2}}}}}$ from 15.4 of ZIF-7 to 43.2-152.8). This enhancement is attributed to the porous interface formed by the hybridization of both frameworks at the molecular level. Furthermore, owing to the flexible structure of the iMOF core, the cMOF-on-iMOF heterostructures with semiconductive soft porous interfaces demonstrated high flexibility in sensing and electrical "shape memory" toward acetone and CO2. This behavior was observed through the guest-induced structural changes of the iMOF core, as revealed by the operando synchrotron grazing incidence wide-angle X-ray scattering measurements.

This study investigates the use of chitosan hydrogel microspheres as a template for growing an extended network of MOF-type HKUST-1. Different drying methods (supercritical CO2, freeze-drying, and vacuum drying) were used to generate three-dimensional polysaccharide nanofibrils embedding MOF nanoclusters. The resulting HKUST-1@Chitosan beads exhibit uniform and stable loadings of HKUST-1 and were used for the adsorption of CO2, CH4, Xe, and Kr. The maximum adsorption capacity of CO2 was found to be 1.98 mmol·g-1 at 298 K and 1 bar, which is significantly higher than those of most MOF-based composite materials. Based on Henry's constants, thus-prepared HKUST-1@CS beads also exhibit fair selectivity for CO2 over CH4 and Xe over Kr, making them promising candidates for capture and separation applications.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Conductive-on-insulating metal–organic framework (cMOF-on-iMOF) heterostructured nanocrystals are reported by Ken-ichi Otake, Susumu Kitagawa et al. in their Research Article (e202303903). These nanocrystals combine soft porosity and electrical properties into a single material. They exhibit semiconductive soft porous interfaces that connect a flexible core and a chemiresistive shell. The cMOF-on-iMOF nanocrystals demonstrate enhanced selective sorption towards CO2, as well as readable softness, electrical gating, and shape memory effects for the guest-responsive iMOF core.

The safe storage of flammable gases, such as acetylene, is essential for current industrial purposes. However, the narrow pressure ( P ) and temperature range required for the industrial use of pure acetylene (100 < P < 200 kPa at 298 K) and its explosive behaviour at higher pressures make its storage and release challenging. Flexible metal–organic frameworks that exhibit a gated adsorption/desorption behaviour—in which guest uptake and release occur above threshold pressures, usually accompanied by framework deformations—have shown promise as storage adsorbents. Herein, the pressures for gas uptake and release of a series of zinc-based mixed-ligand catenated metal–organic frameworks were controlled by decorating its ligands with two different functional groups and changing their ratio. This affects the deformation energy of the framework, which in turn controls the gated behaviour. The materials offer good performances for acetylene storage with a usable capacity of ~90 v/v (77% of the overall amount) at 298 K and under a practical pressure range (100–150 kPa).