Cu(I)-Induced 'Click Reaction' Involving Coordination and Covalent Assembly of Hybrid Borates for the Electrocatalytic CO2 Reduction

The design and synthesis of hybrid borates by the organic ligand modification method are urgent and undeveloped areas of research. It is difficult to directly integrate organoboronic acids within inorganic borate chemistry by adopting the traditional preparation approaches. This work reports a facile synthetic method to synthesize a large family of pyrazole molecule-protected borates in a rapid and precise manner under mild conditions. A unique cyclic eight-membered B4O4-ring has been identified as the cluster core for all these hybrid borates with two different conformations (boat and crown). This strategy can be applied to a system of pyrazolyl molecules to generate such hybrid borates in two independent routes from organoboronic or inorganic boric acids. Furtherly, the mechanism of 'click reaction' between boric acid and pyrazole induced by copper ions has been proposed based on the synthetic conditions and the structure of intermediate. Due to the bimetallic Cu sites and the functional surfaces, these materials can be used as electrocatalysts for CO2 reduction reaction and efficiently enhance the selectivity of HCOOH and C2H4. Our strategy can be regarded as a typical template technique for organic molecule-protected borates.

Ligand Circuit Concept for Developing Gas Separation Materials from Pore-Space-Partitioned Metal-Organic Frameworks

Isoreticular chemistry is among the most powerful strategies for designing novel materials with optimizable pore geometry and properties. Of great significance to the further advance of isoreticular chemistry is the development of broadly applicable new concepts capable of guiding and systematizing the ligand-family expansion as well as establishing correlations between dissimilar and seemingly uncorrelated ligands for better predictive synthetic design and more insightful structure and property analysis. Here ligand circuit concept is proposed and its use has been demonstrated for the synthesis of a family of highly stable, high-performance pore-space-partitioned materials based on an acyclic ligand, trans, trans-muconic acid. This work represents a key step toward developing highly porous and highly stable pore-space-partitioned materials from acyclic ligands. The new materials exhibit excellent sorption properties such as high uptake capacity for CO2 (81.3 cm3 g-1) and C2H2 (165.4 cm3 g-1) by CPM-7.3a-NiV. CPM-7.3a-CoV shows C2H6-selective C2H6/C2H4 separation properties and its high uptakes for C2H4 (134.0 cm3 g-1) and C2H6 (148.0 cm3 g-1) at 1 bar and 298 K contribute to the separation potential of 1.35 mmol g-1. The multi-cycle breakthrough experiment confirms the promising separation performance for C2H2/CO2.

Impact of Postsynthetic Modification on the Covalent Organic Framework (COF) Structures

Covalent organic frameworks (COFs) have emerged as a versatile class of materials owing to their well-defined crystalline structures and inherent porosity. In the realm of COFs, their appeal lies in their customizable nature, which can be further enhanced by incorporating diverse functionalities. Postsynthetic modifications (PSMs) emerge as a potent strategy, facilitating the introduction of desired functionalities postsynthesis. A significant challenge in PSM pertains to preserving the crystallinity and porosity of the COFs. In this study, we aim to investigate the intricate interplay between PSM strategies and the resulting crystalline and porous structures of the COFs. The investigation delves into the diverse methodologies employed in PSMs, to elucidate their distinct influences on the crystallinity and porosity of the COFs. Through a comprehensive analysis of recent advancements and case studies, the study highlights the intricate relationships among PSM parameters, including reaction conditions, precursor selection, and functional groups, and their impact on the structural features of COFs. By understanding how PSM strategies can fine-tune the crystalline and porous characteristics of COFs, researchers can harness this knowledge to design COFs with tailored properties for specific applications, contributing to the advancement of functional materials in diverse fields. This work not only deepens our understanding of COFs but also provides valuable insights into the broader realm of PSM strategies for other solid materials.

Ultrastable Carboxyl-Functionalized Pore-Space-Partitioned Metal-Organic Frameworks for Gas Separation

Isoreticular chemistry, which enables property optimization by changing compositions without changing topology, is a powerful synthetic strategy. One of the biggest challenges facing isoreticular chemistry is to extend it to ligands with strongly coordinating substituent groups such as unbound -COOH, because competitive interactions between such groups and metal ions can derail isoreticular chemistry. It is even more challenging to have an isoreticular series of carboxyl-functionalized MOFs capable of encompassing chemically disparate metal ions. Here, with the simultaneous introduction of carboxyl functionalization and pore space partition, a family of carboxyl-functionalized materials is developed in diverse compositions from homometallic Cr3+ and Ni2+ to heterometallic Co2+/V3+, Ni2+/V3+, Co2+/In3+, Co2+/Ni2+. Cr-MOFs remain highly crystalline in boiling water. Unprecedentedly, one Cr-MOF can withstand the treatment cycle with 10m NaOH and 12m HCl, allowing reversible inter-conversion between unbound -COOH acid form and -COO- base form. These materials exhibit excellent sorption properties such as high uptake capacity for CO2 (100.2 cm3 g-1) and hydrocarbon gases (e.g., 142.1 cm3 g-1 for C2H2, 110.5 cm3 g-1 for C2H4) at 1 bar and 298K, high benzene/cyclohexane selectivity (up to ≈40), and promising separation performance for gas mixtures such as C2H2/CO2 and C2H2/C2H4.

Multi-Stage Optimization of Pore Size and Shape in Pore-Space-Partitioned Metal-Organic Frameworks for Highly Selective and Sensitive Benzene Capture

Compared to exploratory development of new structure types, pushing the limits of isoreticular synthesis on a high-performance MOF platform may have higher probability of achieving targeted properties. Multi-modular MOF platforms could offer even more opportunities by expanding the scope of isoreticular chemistry. However, navigating isoreticular chemistry towards best properties on a multi-modular platform is challenging due to multiple interconnected pathways. Here on the multi-modular pacs (partitioned acs) platform, we demonstrate accessibility to a new regime of pore geometry using two independently adjustable modules (framework-forming module 1 and pore-partitioning module 2). A series of new pacs materials have been made. Benzene/cyclohexane selectivity is tuned, progressively, from 4.5 to 15.6 to 195.4 and to 482.5 by pushing the boundary of the pacs platform towards the smallest modules known so far. The exceptional stability of these materials in retaining both porosity and single crystallinity enables single-crystal diffraction studies of different crystal forms (as-synthesized, activated, guest-loaded) that help reveal the mechanistic aspects of adsorption in pacs materials.

Full-Color Emissive Zirconium-Organic Frameworks Constructed via in Situ "One-Pot" Single-Site Modification for Tryptophan Detection and Energy Transfer

Organic linker-based luminescent metal-organic frameworks (LMOFs) have received extensive studies due to the unlimited species of emissive organic linkers and tunable structure of MOFs. However, the multiple-step organic synthesis is always a great challenge for the development of LMOFs. As an alternative strategy, in situ "one-pot" strategy, in which the generation of emissive organic linkers and sequential construction of LMOFs happen in one reaction condition, can avoid time-consuming pre-synthesis of organic linkers. In the present work, we demonstrate the successful utilization of in situ "one-pot" strategy to construct a series of LMOFs via the single-site modification between the reaction of aldehydes and o-phenylenediamine-based tetratopic carboxylic acid. The resultant MOFs possess csq topology with emission covering blue to near-infrared. The nanosized LMOFs exhibit excellent sensitivity and selectivity for tryptophan detection. In addition, two component-based LMOFs can also be prepared via the in situ "one-pot" strategy and used to study energy transfer. This work not only reports the construction of LMOFs with full-color emissions, which can be utilized for various applications, but also indicates that in situ "one-pot" strategy indeed is a useful and powerful method to complement the traditional MOFs construction method for preparing porous materials with tunable functionalities and properties.

Reversible Adsorption of Ammonia in the Crystalline Solid of a CO2H-Functionalized Cyclic Oligophenylene

Ammonia (NH3) is a viable candidate for the storage and distribution of hydrogen (H2) due to its exceptional volumetric and gravimetric hydrogen energy density. Therefore, it is desirable to develop NH3 storage materials that exhibit robust stability across numerous adsorption-desorption cycles. While porous materials with polymeric frameworks are often used for NH3 capture, achieving reversible NH3 uptake remains a formidable challenge, primarily due to the high reactivity of NH3. Here, we advocate the use of CO2H-functionalized cyclic oligophenylene 1a with high chemical stability as a novel single-molecule-based adsorbent for NH3. Simple reprecipitation of 1a selectively yielded microporous crystalline solid 1a (N). Crystalline 1a (N) adsorbs up to 8.27 mmol/g of NH3 at 100 kPa and 293 K. Adsorbed NH3 in the pore of 1a (N) has a packing density of 0.533 g/cm3 at 293 K, which is close to the density of liquid NH3 (0.681 g/cm3 at 240 K). Crystalline 1a (N) also exhibits reversible NH3 adsorption over at least nine cycles, sustaining its storage capacity (1st cycle: 8.27 mmol/g; 9th cycle: 8.25 mmol/g at 100 kPa and 293 K) and crystallinity. During each desorption cycle, NH3 was removed from 1a (N) under reduced pressure (∼65 Pa), leaving <3% of the total uptake, and 1a (N) was fully purged under dynamic vacuum conditions (∼5 × 10-4 Pa at 293 K for 1 h) before the subsequent adsorption cycles. Thus, microporous crystalline 1a (N) can reliably adsorb and desorb NH3 repeatedly, which avoids the need for heat-based activation between cycles.

Advancing Pore-Space-Partitioned Metal-Organic Frameworks with Isoreticular Cluster Concept

Trigonal planar M3(O/OH) trimers are among the most important clusters in inorganic chemistry and are the foundational features of multiple high-impact MOF platforms. Here we introduce a concept called isoreticular cluster series and demonstrate that M3(O/OH), as the first member of a supertrimer series, can be combined with a higher hierarchical member (double-deck trimer here) to advance isoreticular chemistry. We report here an isoreticular series of pore-space-partitioned MOFs called M3M6 pacs made from co-assembly between M3 single-deck trimer and M3x2 double-deck trimer. Important factors were identified on this multi-modular MOF platform to guide optimization of each module, which enables the phase selection of M3M6 pacs by overcoming the formation of previously-always-observed same-cluster phases. The new pacs materials exhibit high surface area and high uptake capacity for CO2 and small hydrocarbons, as well as selective adsorption properties relevant to separation of industrially important mixtures such as C2H2/CO2 and C2H2/C2H4. Furthermore, new M3M6 pacs materials show electrocatalytic properties with high activity.

Tailorable Multi-Modular Pore-Space-Partitioned Vanadium Metal-Organic Frameworks for Gas Separation

Currently, few porous vanadium metal-organic frameworks (V-MOFs) are known and even fewer are obtainable as single crystals, resulting in limited information on their structures and properties. Here this work demonstrates remarkable promise of V-MOFs by presenting an extensible family of V-MOFs with tailorable pore geometry and properties. The synthesis leverages inter-modular synergy on a tri-modular pore-partitioned platform. New V-MOFs show a broad range of structural features and sorption properties suitable for gas storage and separation applications for C2H2/CO2, C2H6/C2H4, and C3H8/C3H6. The c/a ratio of the hexagonal cell, a measure of pore shape, is tunable from 0.612 to 1.258. Other tunable properties include pore size from 5.0 to 10.9 Å and surface area from 820 to 2964 m2 g-1. With C2H2/CO2 selectivity from 3.3 to 11 and high uptake capacity for C2H2 from 65.2 to 182 cm3 g-1 (298K, 1 bar), an efficient separation is confirmed by breakthrough experiments. The near-record high uptake for C2H6 (166.8 cm3 g-1) contributes to the promise for C2H6-selective separation of C2H6/C2H4. The multi-module pore expansion enables transition from C3H6-selective to more desirable C3H8-selective separation with extraordinarily high C3H8 uptake (254.9 cm3 g-1) and high separation potential (1.25 mmol g-1) for C3H8/C3H6 (50:50 v/v) mixture.

Pore Space Partition Synthetic Strategy in Imine-linked Multivariate Covalent Organic Frameworks

Partitioning the pores of covalent organic frameworks (COFs) is an attractive strategy for introducing microporosity and achieving new functionality, but it is technically challenging to achieve. Herein, we report a simple strategy for partitioning the micropores/mesopores of multivariate COFs. Our approach relies on the predesign and synthesis of multicomponent COFs through imine condensation reactions with aldehyde groups anchored in the COF pores, followed by inserting additional symmetric building blocks (with C2 or C3 symmetries) as pore partition agents. This approach allowed tetragonal or hexagonal pores to be partitioned into two or three smaller micropores, respectively. The synthesized library of pore-partitioned COFs was then applied for the capture of iodine pollutants (i.e., I2 and CH3I). This rich inventory allowed deep exploration of the relationships between the COF adsorbent composition, pore architecture, and adsorption capacity for I2 and CH3I capture under wide-ranging conditions. Notably, one of our developed pore-partitioned COFs (COF 3-2P) exhibited greatly enhanced dynamic I2 and CH3I adsorption performances compared to its parent COF (COF 3) in breakthrough tests, setting a new benchmark for COF-based adsorbents. Results present an effective design strategy toward functional COFs with tunable pore environments, functions, and properties.

Multi-Modular Design of Stable Pore-Space-Partitioned Metal-Organic Frameworks for Gas Separation Applications

Pore space partition (PSP) is an effective materials design method for developing high-performance small-pore materials for storage and separation of gas molecules. The continued success of PSP depends on broad availability and judicious choice of pore-partition ligands and better understanding of each structural module on stability and sorption properties. Here, by using substructural bioisosteric strategy (sub-BIS), a dramatic expansion of pore-partitioned materials is targeted by using ditopic dipyridyl ligands with non-aromatic cores or extenders, as well as by expanding heterometallic clusters to uncommon nickel-vanadium and nickel-indium clusters rarely known before in porous materials. The dual-module iterative refinement of pore-partition ligands and trimers leads to remarkable enhancement of chemical stability and porosity. Here a family of 23 pore-partitioned materials synthesized from five pore-partition ligands and seven types of trimeric clusters is reported. New materials with such compositionally and structurally diverse framework modules reveal key factors that dictate stability, porosity, and gas separation properties. Among these, materials based on heterometallic vanadium-nickel trimeric clusters give rise to the highest long-term hydrolytic stability and remarkable uptake capacity for CO2 , C2 H2 /C2 H4 /C2 H6 , and C3 H6 /C3 H8 hydrocarbon gases. The breakthrough experiment shows the potential application of new materials for separating gas mixtures such as C2 H2 /CO2 .

Covalent organic frameworks: linkage types, synthetic methods and bio-related applications

Covalent organic frameworks (COFs) are composed of small organic molecules linked via covalent bonds, which have tunable mesoporous structure, good biocompatibility and functional diversities. These excellent properties make COFs a promising candidate for constructing biomedical nanoplatforms and provide ample opportunities for nanomedicine development. A systematic review of the linkage types and synthesis methods of COFs is of indispensable value for their biomedical applications. In this review, we first summarize the types of various linkages of COFs and their corresponding properties. Then, we highlight the reaction temperature, solvent and reaction time required by different synthesis methods and show the most suitable synthesis method by comparing the merits and demerits of various methods. To appreciate the cutting-edge research on COFs in bioscience technology, we also summarize the bio-related applications of COFs, including drug delivery, tumor therapy, bioimaging, biosensing and antimicrobial applications. We hope to provide insight into the interdisciplinary research on COFs and promote the development of COF nanomaterials for biomedical applications and their future clinical translations.

Cyclobutanedicarboxylate Metal-Organic Frameworks as a Platform for Dramatic Amplification of Pore Partition Effect

Ultrafine tuning of MOF structures at subangstrom or picometer levels can help improve separation selectivity for gases with subtle differences. However, for MOFs with a large enough pore size, the effect from ultrafine tuning on sorption can be muted. Here we show an integrative strategy that couples extreme pore compression with ultrafine pore tuning. This strategy is made possible by unique combination of two features of the partitioned acs (pacs) platform: multimodular framework and exceptional tolerance toward isoreticular replacement. Specifically, we use one module (ligand 1, L1) to shrink the pore size to an extreme minimum on pacs. A compression ratio of about 30% was achieved (based on the unit cell c/a ratio) from prototypical 1,4-benzenedicarboxylate-pacs to trans-1,3-cyclobutanedicarboxylate-pacs. This is followed by using another module (ligand 2, L2) for ultrafine pore tuning (<3% compression). This L1-L2 strategy increases the C2H2/CO2 selectivity from 2.6 to 20.8 and gives rise to an excellent experimental breakthrough performance. As the shortest cyclic dicarboxylate that mimics p-benzene-based moieties using a bioisosteric (BIS) strategy on pacs, trans-1,3-cyclobutanedicarboxylate offers new opportunities in MOF chemistry.

Composite materials based on covalent organic frameworks for multiple advanced applications

Covalent organic frameworks (COFs) stand for a class of emerging crystalline porous organic materials, which are ingeniously constructed with organic units through strong covalent bonds. Their excellent design capabilities, and uniform and tunable pore structure make them potential materials for various applications. With the continuous development of synthesis technique and nanoscience, COFs have been successfully combined with a variety of functional materials to form COFs-based composites with superior performance than individual components. This paper offers an overview of the development of different types of COFs-based composites reported so far, with particular focus on the applications of COFs-based composites. Moreover, the challenges and future development prospects of COFs-based composites are presented. We anticipate that the review will provide some inspiration for the further development of COFs-based composites.

Simultaneous Control of Flexibility and Rigidity in Pore-Space-Partitioned Metal-Organic Frameworks

Flexi-MOFs are typically limited to low-connected (<9) frameworks. Here we report a platform-wide approach capable of creating a family of high-connected materials (collectively called CPM-220) that integrate exceptional framework flexibility with high rigidity. We show that the multi-module nature of the pore-space-partitioned pacs (partitioned acs net) platform allows us to introduce flexibility as well as to simultaneously impose high rigidity in a tunable module-specific fashion. The inter-modular synergy has remarkable macro-morphological and sub-nanometer structural impacts. A prominent manifestation at both length scales is the retention of X-ray-quality single crystallinity despite huge hexagonal c-axial contraction (≈ 30%) and harsh sample treatment such as degassing and sorption cycles. CPM-220 sets multiple precedents and benchmarks on the pacs platform in both structural and sorption properties. They possess exceptionally high benzene/cyclohexane selectivity, unusual C₃H₆ and C₃H₈ isotherms, and promising separation performance for small gas molecules such as C₂H₂/CO₂.

Covalent Organic Frameworks: The Rising-Star Platforms for the Design of CO2 Separation Membranes

Membrane-based carbon dioxide (CO₂ ) capture and separation technologies have aroused great interest in industry and academia due to their great potential to combat current global warming, reduce energy consumption in chemical separation of raw materials, and achieve carbon neutrality. The emerging covalent organic frameworks (COFs) composed of organic linkers via reversible covalent bonds are a class of porous crystalline polymers with regular and extended structures. The inherent structure and customizable organic linkers give COFs high and permanent porosity, short transport channel, tunable functionality, and excellent stability, thereby enabling them rising-star alternatives for developing advanced CO₂ separation membranes. Therefore, the promising research areas ranging from development of COF membranes to their separation applications have emerged. Herein, this review first introduces the main advantages of COFs as the state-of-the-art membranes in CO₂ separation, including tunable pore size, modifiable surfaces property, adjustable surface charge, excellent stability. Then, the preparation approaches of COF-based membranes are systematically summarized, including in situ growth, layer-by-layer stacking, blending, and interface engineering. Subsequently, the key advances of COF-based membranes in separating various CO₂ mixed gases, such as CO₂ /CH₄ , CO₂ /H₂ , CO₂ /N₂ , and CO₂ /He, are comprehensively discussed. Finally, the current issues and further research expectations in this field are proposed.

Solvent-free Synthesis of Multi-Module Pore-Space-Partitioned Metal-Organic Frameworks for Gas Separation

Multi-module design of framework materials with multiple distinct building blocks has attracted much attention because such materials are more amenable to compositional and geometrical tuning and thus offer more opportunities for property optimization. Few examples are known that use environmentally friendly and cost-effective solvent-free method to synthesize such materials. Here, we report the use of solvent-free method (also modulator-free) to synthesize a series of multi-module MOFs with high stability and separation property for C₂ H₂ /CO₂ . The synthesis only requires simple mixing of reactants and short reaction time (2 h). Highly porous and stable materials can be made without any post-synthetic activation. The success of solvent-free synthesis of multi-module MOFs reflects the synergy between different modules, resulting in stable pore-partitioned materials, despite the fact that other competitive crystallization pathways with simpler framework compositions also exist.

Facile synthesis of Co-Ni layered double hydroxides nanosheets wrapped on a prism-like metal-organic framework for efficient oxygen evolution reaction

The construction of low-cost oxygen evolution reaction (OER) electrocatalysts with high activity and good durability is a considerable challenge for facilitating the efficient utilization of green energy. Herein, the prism-like materials of institute lavoisier frameworks-88 (MIL-88) was first synthesized by a hydrothermal method. Then, Co-Ni layered double hydroxides (CoNi-LDHs) nanosheets were directly wrapped on the MIL-88 surface by electrodeposition to form core-shell MIL-88@CoNi-LDHs composites. Due to the distinct structure and synergistic effect between the MIL-88 core and CoNi-LDHs shell, it was found that MIL-88@CoNi-LDHs had outstanding OER activity with a small Tafel slope (45.55 mV dec^-1), low overpotential (314 mV) at 10 mA cm^-2, and superior durability. This study provides a prospective pathway to exploit highly efficient low-cost electrocatalysts for OER.

Developing Water-Stable Pore-Partitioned Metal-Organic Frameworks with Multi-Level Symmetry for High-Performance Sorption Applications

A new perspective is proposed in the design of pore-space-partitioned MOFs that is focused on ligand symmetry properties sub-divided here into three hierarchical levels: 1) overall ligand, 2) ligand substructure such as backbone or core, and 3) the substituent groups. Different combinations of the above symmetry properties exist. Given the close correlation between nature of chemical moiety and its symmetry, such a unique perspective into ligand symmetry and sub-symmetry in MOF design translates into the influences on MOF properties. Five new MOFs have been prepared that exhibit excellent hydrothermal stability and high-performance adsorption properties with potential applications such as C₃ H₆ /C₂ H₄ and C₂ H₂ /CO₂ selective adsorption. The combination of high stability with high benzene/cyclohexane selectivity of ≈13.7 is also of particular interest.

MOF/COF hybrids as next generation materials for energy and biomedical applications

The rapid increase in the number and variety of metal organic frameworks (MOFs) and covalent organic frameworks (COFs) has led to groundbreaking applications in the field of materials science and engineering. New MOF/COF hybrids combine the outstanding features of MOF and COF structures, such as high crystallinities, large surface areas, high porosities, the ability to decorate the structures with functional groups, and improved chemical and mechanical stabilities. These new hybrid materials offer promising performances for a wide range of applications including catalysis, energy storage, gas separation, and nanomedicine. In this highlight, we discuss the recent advancements of MOF/COF hybrids as next generation materials for energy and biomedical applications with a special focus on the use of computational tools to address the opportunities and challenges of using MOF/COF hybrids for various applications.

Tuning the Pore Environment of MOFs toward Efficient CH4/N2 Separation under Humid Conditions

Adsorption separation technology using adsorbents is promising as an alternative to the energy-demanding cryogenic distillation of natural gas (CH₄/N₂) separation. Although a few adsorbents, such as metal-organic frameworks (MOFs), with high performance for CH₄/N₂ separation, have been reported, it is still challenging to target the desired adsorbents for the actual CH₄/N₂ separation under humid conditions because the adsorption capacity and selectivity of the adsorbents might be mainly dampened by water vapor. Except for the high CH₄ uptake and CH₄/N₂ selectivity, the adsorption material should simultaneously have excellent stability against moisture and relatively low-water absorption affinity. Here, we tuned the ligands and metal sites of reticular MOFs, Zn-benzene-1,4-dicarboxylic acid-1,4-diazabicyclo[2.2.2]octane (Zn-BDC-DABCO) (DMOF), affording a series of isostructural MOFs (DMOF-N, DMOF-A₁, DMOF-A₂, and DMOF-A₃). Because of the finely engineered pore size and introduced aromatic rings in the functional DMOF, gas sorption results reveal that the materials show improved performance with a benchmark CH₄ uptake of 37 cm³/g and a high CH₄/N₂ adsorption selectivity of 7.2 for DMOF-A₂ at 298 K and 1.0 bar. Moisture stability experiments show that DMOF-A₂ is a robust MOF with low water vapor capacity even at ∼40% relative humidity (RH) because of the presence of more hydrophobic aromatic rings. Breakthrough experiments verify the excellent CH₄/N₂ separation performances of DMOF-A₂ under high humidity.

Simultaneous Control of Pore-Space Partition and Charge Distribution in Multi-Modular Metal-Organic Frameworks

We report here a strategy for making anionic pacs type porous materials by combining pore space partition with charge reallocation. The method uses the first negatively charged pore partition ligand (2,5,8-tri-(4-pyridyl)-1,3,4,6,7,9-hexaazaphenalene, H-tph) that simultaneously enables pore partition and charge reallocation. Over two dozen anionic pacs materials have been made to demonstrate their excellent chemical stability and a high degree of tunability. Notably, Ni₃ -bdt-tph (bdt=1,4-benzeneditetrazolate) exhibits month-long water stability, while CoV-bdt-tph sets a new benchmark for C₂ H₂ storage capacity under ambient conditions for ionic MOFs. In addition to tunable in-framework modules, we show feasibility to tune the type and concentration of extra-framework counter cations and their influence on both stability and capability to separate industrial C₃ H₈ /C₃ H₆ and C₆ H₆ /C₆ H₁₂ mixtures.

Chiral copper(i)–organic frameworks for dye degradation and the enantioselective recognition of amino acids

Four novel chiral CMOFs with a 2D layered hexagonal network have been prepared and used for dye adsorption and degradation. Furthermore, one exhibits different adsorption rates and efficiencies for chiral amino acids.

Syntheses of New Zeolitic Imidazolate Frameworks in Dimethyl Sulfoxide

Presented here are the syntheses of ZIFs in dimethyl sulfoxide (DMSO). A series of new ZIFs with various topologies such as ACO, coi, zni, ANA, GIS, even new topology can...

Tailoring Multiple Sites of Metal-Organic Frameworks for Highly Efficient and Reversible Ammonia Adsorption

The structural diversity and designability of metal-organic frameworks (MOFs) make these porous materials a strong candidate for NH₃ uptake. However, to achieve a high NH₃ capture capacity and good recyclability of MOFs at the same time remains a great challenge. Here, a multiple-site ligand screening strategy of MOFs is proposed for highly efficient and reversible NH₃ uptake for the first time. Based on the optimized DFT results for various possible ligands, pyrazole-3,5-dicarboxylate with multiple sites was screened as the best ligand to construct robust MOF-303(Al) with Al³⁺. It is experimentally found that the NH₃ adsorption capacity of MOF-303(Al) is as high as 19.7 mmol g^-1 at 25.0 °C and 1.0 bar, and the NH₃ capture is fully reversible and no clear loss of capture capacity is observed after 20 cycles of adsorption-desorption. Various spectral studies verify that the superior NH₃ capacity and excellent recyclability of MOF-303(Al) are mainly attributed to the hydrogen bonding interactions of NH₃ with multiple sites of MOF-303(Al).

A {Ni12}-Wheel-Based Metal-Organic Framework for Coordinative Binding of Sulphur Dioxide and Nitrogen Dioxide

Air pollutions by SO 2 and NO 2 have caused significant risks on the environment and human health. Understanding the mechanism of active sites within capture materials is of fundamental importance to the development of new clean-up technologies. Here we report the crystallographic observation of reversible coordinative binding of SO 2 and NO 2 on open Ni(II) sites in a metal-organic framework (NKU-100) incorporating an unprecedented {Ni 12 }-wheel, which exhibits six open Ni(II) sites on desolvation. Immobilised gas molecules are further stabilised by cooperative host-guest interactions comprised of hydrogen bonds, π ··· π interactions and dipole interactions. At 298 K and 1.0 bar, NKU-100 shows adsorption uptakes of 6.21 and 5.80 mmol g -1 for SO 2 and NO 2 , respectively. Dynamic breakthrough experiments have confirmed the selective retention of SO 2 and NO 2 at low concentrations under dry conditions. This work will inspire the future design of efficient sorbents for the capture of SO 2 and NO 2 .

Pore-Space Partition and Optimization for Propane-Selective High-Performance Propane/Propylene Separation

The development of effective propane (C3H8)-selective adsorbents for the purification of propylene (C3H6) from C3H8/C3H6 mixture is a promising alternative to replace the energy-intensive cryogenic distillation. However, few materials possess the dual desirable features of propane selectivity and high uptake capacity. Here, we report a family of pore-space-partitioned crystalline porous materials (CPM) with remarkable C3H8 uptake capacity (up to 10.9 mmol/g) and the highly desirable yet uncommon C3H8 selectivity (up to 1.54 at 0.1 bar and 1.44 at 1 bar). The selectivity-capacity synergy endows them with record-performing C3H8/C3H6 separation potential (i.e., C3H6 recovered from the mixture). Moreover, these CPMs exhibit outstanding properties including high stability, low regeneration energy, and multimodular chemical and geometrical tunability within the same isoreticular framework. The high C3H8/C3H6 separation performance was further confirmed by the breakthrough experiments.

Rational Design and Growth of MOF-on-MOF Heterostructures

Multiporous metal-organic frameworks (MOFs) have emerged as a subclass of highly crystalline inorganic-organic materials, which are endowed with high surface areas, tunable pores, and fascinating nanostructures. Heterostructured MOF-on-MOF composites are recently becoming a research hotspot in the field of chemistry and materials science, which focus on the assembly of two or more different homogeneous or heterogeneous MOFs with various structures and morphologies. Compared with one single MOF, the dual MOF-on-MOF composites exhibit unprecedented tunability, hierarchical nanostructure, synergistic effect, and enhanced performance. Due to the difference of inorganic metals and organic ligands, the lattice parameters in a, b, and c directions in the single crystal cells could bring about subtle or large structural difference. It will result in the composite material with distinct growth methods to obtain secondary MOF grown from the initial MOF. In this review, the authors wish to mainly outline the latest synthetic strategies of heterostructured MOF-on-MOFs and their derivatives, including ordered epitaxial growth, random epitaxial growth, etc., which show the tutorial guidelines for the further development of various MOF-on-MOFs.

Tunable Metal-Organic Frameworks Based on 8-Connected Metal Trimers for High Ethane Uptake

Metal trimers [M₃ (O/OH)](OOCR)₆ are among the most important structural building blocks. From these trimers, a great success has been achieved in the design of 6- or 9-connected framework materials with various topological features and outstanding gas-sorption properties. In comparison, 8-connected trimer-based metal-organic frameworks (MOFs) are rare. Given multiple competitive pathways for the formation of 6- or 9-connected frameworks, it remains challenging to identify synthetic or structural parameters that can be used to direct the self-assembly process toward trimer-based 8-connected materials. Here, a viable strategy called angle bending modulation is revealed for creating a prototypical MOF type based on 8-connected M₃ (OH)(OOCR)₅ (Py-R)₃ trimers (M = Zn, Co, Fe). As a proof of concept, six members in this family are synthesized using three types of ligands (CPM-80, -81, and -82). These materials do not possess open-metal sites and show excellent uptake capacity for various hydrocarbon gas molecules and inverse C₂ H₆ /C₂ H₄ selectivity. CPM-81-Co, made from 2,5-furandicarboxylate and isonicotinate, features selectivity of 1.80 with high uptake capacity for ethane (123 cm³ g^-1 ) and ethylene (113 cm³ g^-1 ) at 298 K and 1 bar.

Precise Pore Space Partitions Combined with High-Density Hydrogen-Bonding Acceptors within Metal-Organic Frameworks for Highly Efficient Acetylene Storage and Separation

The high storage capacity versus high selectivity trade-off barrier presents a daunting challenge to practical application as an acetylene (C₂ H₂ ) adsorbent. A structure-performance relationship screening for sixty-two high-performance metal-organic framework adsorbents reveals that a moderate pore size distribution around 5.0-7.5 Å is critical to fulfill this task. A precise pore space partition approach was involved to partition 1D hexagonal channels of typical MIL-88 architecture into finite segments with pore sizes varying from 4.5 Å (SNNU-26) to 6.4 Å (SNNU-27), 7.1 Å (SNNU-28), and 8.1 Å (SNNU-29). Coupled with bare tetrazole N sites (6 or 12 bare N sites within one cage) as high-density H-bonding acceptors for C₂ H₂ , the target MOFs offer a good combination of high C₂ H₂ /CO₂ adsorption selectivity and high C₂ H₂ uptake capacity in addition to good stability. The optimized SNNU-27-Fe material demonstrates a C₂ H₂ uptake of 182.4 cm³  g^-1 and an extraordinary C₂ H₂ /CO₂ dynamic breakthrough time up to 91 min g^-1 under ambient conditions.

Multidimensional Anisotropic Architectures on Polymeric Microparticles

Next generation life science technologies will require the integration of building blocks with tunable physical and chemical architectures at the microscale. A central issue is to govern the multidimensional anisotropic space that defines these microparticle attributes. However, this control is limited to one or few dimensions due to profound fabrication tradeoffs, a problem that is exacerbated by miniaturization. Here, a vast number of anisotropic dimensions are integrated combining SU-8 photolithography with (bio)chemical modifications via soft-lithography. Microparticles in a 15-D anisotropic space are demonstrated, covering branching, faceting, fiducial, topography, size, aspect ratio, stiffness, (bio)molecular and quantum dot printing, top/bottom surface coverage, and quasi-0D, 1D, 2D, and 3D surface patterning. The strategy permits controlled miniaturization on physical dimensions below 1 µm and molecular patterns below 1 µm² . By combining building blocks, anisotropic microparticles detect pH changes, form the basis for a DNA-assay recognition platform, and obtain an extraordinary volumetric barcoding density up to 1093 codes µm^-3 in a 3 × 12 × 0.5 µm³ volume.

Adjustment of the performance and stability of isostructural zeolitic tetrazolate-imidazolate frameworks

Presented here are two isostructural SOD-type zeolitic tetrazolate-imidazolate frameworks (ZTIFs), Zn(etz)0.86(mim)1.14 (ZTIF-9, Hetz = 5-ethyltetrazole, Hmim = 2-methylimidazole) and Zn(vtz)0.63(mim)1.37 (ZTIF-10, Hvtz = 5-vinyltetrazole). The adjustment of the ligand ratios within these ZTIFs was realized through changing the substituent groups of tetrazole ligands. Remarkably, ZTIF-9 with a suitable ligand ratio perfectly balances gas uptake and stability, exhibiting 6-fold improvement of C2H2 uptake compared to the prototype ZIF-8 (Zn(mim)2).

A Flexible Interpenetrated Zirconium-Based Metal-Organic Framework with High Affinity toward Ammonia

Flexible metal-organic frameworks (MOFs) are highly attractive porous crystalline materials presenting structural changes when exposed to external stimuli, the mechanism of which is often difficult to glean, owing to their complex and dynamic nature. Herein, a flexible interpenetrated Zr-MOF, NU-1401, composed of rare 4-connected Zr₆ nodes and tetratopic naphthalenediimide (NDI)-based carboxylate linkers, was designed. The intra-framework pore opening deformation and inter-framework motions, when subjected to different solvent molecules, were investigated by single-crystal XRD. The distance and overlap angle between the stacked NDI pairs in the entangled structure could be finely tuned, and the interactions between NDI and solvent molecules led to solvochromism. Furthermore, the presence of electron-deficient NDI units in the linker and acid sites on the node of the interpenetrated porous structure offered high density of adsorption sites for ammonia molecules, resulting in high uptake at low pressures.

Modular Total Synthesis in Reticular Chemistry

The idea of modularity in organic total synthesis has promoted the construction of diverse targeted natural products by varying the building blocks and assembly sequences. Yet its utilization has been mainly limited to the synthesis of molecular compounds based on covalent bonds. In this work, we expand the conceptual scope of modular synthesis into framework materials, which bridges metal- and covalent organic frameworks (MOFs and COFs) hierarchically in reticular chemistry. While the assembly sequences are determined by the coordination or the covalent bond strengths, a modular synthesis strategy which progressively links simple building blocks into increasingly sophisticated superstructures was reported. As a result, a series of hierarchical COF-on-MOF structures with architectural intricacy were obtained through sequence-defined reactions of diverse building blocks. The tunability of spatial apportionment, compositions, and functionality was successfully managed in these framework materials. To the best of our knowledge, this is the first report on the synthesis of COF@MOF composites and also the first discovery of controlled COF alignment. This generalizable modularity strategy will not only accelerate the discovery of multicomponent framework materials by the hierarchical assembly of MOFs and COFs but also offer a predictable retrosynthetic route to smart materials with unusual tunability owing to the diverse inorganic or organic building units.

Rational design of multiple Prussian-blue analogues/NF composites for high-performance surpercapacitors

Multiple Prussian-blue analogues/NF composites were successfully fabricated through a one-pot chemical etching and growing process. The target materials NiCo_xFe_1−x-PBA/NF exhibited excellent electrochemical performance.