Yabing He

The construction of multinary metal–organic frameworks (MOFs) incorporating multiple distinct metal clusters within a single framework remains a significant challenge, particularly in copper‐carboxylate systems where binary assemblies predominate. Herein, we report a quaternary copper–carboxylate framework, ZJNU‐175, assembled from a low‐symmetry hexacarboxylate ligand and three distinct copper‐based secondary building units. The material features high porosity (BET surface area of 2321 m ² g ⁻¹ ) and abundant supramolecular recognition sites. It achieves a C ₃ H ₆ uptake of 8.57 mmol g ⁻¹ , an equimolar IAST selectivity of 8.1, and a polymer‐grade C ₂ H ₄ productivity of 5.28 mmol g ⁻¹ , placing it as one of the leading MOF adsorbents for C ₃ H ₆ /C ₂ H ₄ separation. This work highlights ligand symmetry engineering as a promising strategy for constructing multinary MOFs for energy‐efficient hydrocarbon separations.

Pore-space-partitioned metal–organic frameworks (PSP-MOFs) offer a modular platform for gas adsorption, yet the influence of substituents on the pore-dividing agent remains unexplored. Herein, we report the first systematic investigation of substituent effects on 1,3,5-tri(pyridin-4-yl)benzene (TPB)-based pore-dividing ligands in four isostructural partitioned ACS MOFs (PACS-MOFs). By introducing substituents of increasing steric bulk (–H, –NH2, −CH3, and –OCH3) onto a fixed framework, we observe a clear, volume-dependent trend: SF6 uptake, SF6/N2 selectivity, and dynamic breakthrough separation time all follow the order unsubstituted > –NH2 ≈ −CH3 > –OCH3. Notably, the isosteric heats of adsorption for SF6 are remarkably similar across all four MOFs (21.18–26.15 kJ mol–1), confirming that the substituents exert negligible influence on the intrinsic binding sites. The performance differences are therefore dominated by steric hindrance that reduces pore accessibility, rather than by changes in binding affinity. This work establishes a fundamental design principle for PACS-MOFs: substituent volume on pore-dividing agents should be minimized to preserve pore accessibility for optimal separation performance of SF6.

Replacing pure SF6 with SF6/N2 mixtures curbs emissions but demands efficient low-concentration SF6 recovery. We report a gradient enhancement strategy combining cis-trans isomerism and methylation to boost ligand dipole moment and confinement in three isostructural partitioned acs-MOFs (ZJNU-181-trans, -cis, and -2Me). Pre-synthesis DFT predictions of SF6 affinity (2Me > cis > trans) are validated experimentally. At 298 K and 10 kPa, SF6 uptake follows 2Me > cis > trans, consistent with isosteric heats and IAST selectivity (169.8 for 2Me). Breakthrough tests confirm this order, with 2Me showing the largest SF6/N2 breakthrough gap (141.5 min g–1) and excellent recyclability. DFT reveals that methyl groups act as additional C–H···F donors while creating uniform 7.3 Å pores, synergistically enhancing SF6 binding to –33.04 kJ mol–1. This work establishes gradient dipole-confinement modulation as a generalizable MOF design paradigm.

The efficient separation of C₂H₂ from CO₂ and CH₄ remains challenging due to their similar molecular sizes and physical properties. Herein, we report a NbO-type metal-organic framework (MOF) (ZJNU-170) constructed from a thiazolothiazole-based diisophthalate ligand and Cu²⁺ paddlewheel units. The thiazolothiazole heterocycle serves as a hydrogen bond acceptor, enabling C-H···N and C-H···S interactions with C₂H₂. Benefiting from this design, ZJNU-170a exhibits a high C₂H₂ uptake of 237.1 cm³ (STP) g^-1 at 278 K and 1 atm, with a moderate isosteric heat of adsorption of 30.7 kJ mol^-1, achieving a favorable balance between affinity and regenerability. IAST selectivity calculations at 298 K and 1 atm for equimolar mixtures give values of 4.4 for C₂H₂/CO₂ and 29.6 for C₂H₂/CH₄. Dynamic breakthrough experiments confirm practical separation performance for binary and ternary mixtures, delivering high-purity CH₄ (>99.95%) and C₂H₂ (>99.8%) under ambient conditions. Density functional theory (DFT) calculations reveal that open metal sites serve as primary adsorption sites via π-coordination, while thiazolothiazole units provide additional hydrogen-bonding interactions. Collectively, this work presents a promising adsorbent for energy-efficient C₂H₂ purification and offers insights into the rational design of NbO-type MOFs for multicomponent gas separation.

Gas storage and separation are critical for industrial, environmental, and energy sustainability, yet conventional methods like cryogenic distillation and compression suffer from high energy consumption, cost, and infrastructural complexity. Physical adsorption using porous materials, operating without gas-phase transitions, presents a promising alternative due to its low energy requirements and ease of operation. Covalent organic frameworks (COFs), a new class of crystalline porous materials synthesized through covalent bonding, have demonstrated significant potential as adsorbents due to their structural regularity, excellent stability, high surface areas, low density, and tunable pore properties, including the pore size, shape, and environment. These attributes facilitate efficient gas storage and separation. This comprehensive review summarizes the latest advancements in gas storage and separation using COF materials. Adsorption-based methods will be emphasized, with supplementary coverage of membrane-based technology. Based on the properties of gases, the main part will be divided into the following parts: hydrogen storage, methane storage, hydrocarbon separation, CO₂ capture, SO₂ capture, SF₆ capture, H₂/D₂ separation, NH₃ separation, and CH₄/N₂ and O₂/N₂ separations. In addition, the underlying mechanisms of separation, the innovation in COF structural design, and the strategies (e.g., bottom-up synthesis, post-synthetic modification, and interpenetration regulation) employed to enhance storage or separation performance will be analyzed. Finally, this work will outline the key challenges in translating COF materials from laboratory research to industrial applications, while highlighting the prospects of future developments in COF materials for gas storage and separation.

Ultradry ethanol is widely and crucially used in industry, primarily owing to its excellent solvent properties, reactivity, relatively low toxicity, and volatility. However, trace amounts of water present within it can significantly diminish its efficacy. Herein, we designed a low-cost and green-synthesized metal-organic framework material (ZNU-68) for kinetic ethanol/water separation. Owing to its larger kinetic diameter compared to water, ethanol diffuses more slowly within the pores, consequently leading to differences in both the adsorption capacity and adsorption rate. Ten cycles of dynamic vapor adsorption tests for water confirm that ZNU-68 possesses excellent stability and regenerability. Under a feed composition of ethanol/water = 95/5, a high productivity of anhydrous ethanol (18.36 mol/kg) is achieved. Density functional theory calculations and water-loaded single-crystal structures indicate that ZNU-68 has two distinct adsorption sites for water molecules.

The development of efficient methane (CH₄) purification technology from natural gas is crucial to its utilization. Adsorptive separation using porous metal-organic frameworks (MOFs) offers a promising and energy-efficient strategy. Herein, a novel carborane hybrid MOF, Cu-CB-DMTPA, was solvothermally synthesized by using Cu²⁺, p-C₂B₁₀H₁₀-(COOH)₂, and 2,6-dimethyl-N,N-di(pyridin-4-yl)pyridin-4-amine (DMTPA). This material features electronegative pore surfaces rich in B-H^δ- groups and unique one-dimensional (1D) channels with dual pore sizes (large: 6.5 × 4.3 Ų; small: 3.4 × 2.8 Ų). Gas adsorption studies revealed significantly higher uptake of C₃H₈ (29.9 cm³ g^-1) and C₂H₆ (31.3 cm³ g^-1) over CH₄ (9.9 cm³ g^-1) at 298 K and 1.0 bar. Ideal adsorbed solution theory (IAST) selectivity calculations demonstrated outstanding performance for equimolar C₃H₈/CH₄ (61.2) and C₂H₆/CH₄ (14.4) separations, outperforming many popular materials. The separation mechanism, probed via in situ single-crystal X-ray diffraction (SCXRD) and Grand Canonical Monte Carlo (GCMC) simulations, is attributed to multiple cooperative weak interactions between the framework and hydrocarbons, with stronger binding affinity for larger and more polarizable molecules. Dynamic breakthrough experiments confirmed efficient one-step purification of CH₄ (>99.99% purity) from a CH₄/C₂H₆/C₃H₈ (85:10:5) mixture at 298 K, achieving a high CH₄ productivity of 81.53 L kg^-1. Cu-CB-DMTPA also maintains excellent recyclability and humidity resistance, highlighting its potential for industrial natural gas upgrading.

Organic dye pollutants pose a serious threat to ecosystems and human health, whereas there still exist challenges in efficient and selective adsorption of them due to the difficulty in structure tunability of traditional adsorption materials. Based on the tailorable pore structure of anionic metal‐organic frameworks (MOFs), the pore size can be optimized to match the dye molecules through a solvothermal control strategy, thereby achieving efficient adsorption. Herein, the pore size of anionic MOFs was modulated by varying solvents and temperature, facilitating high‐performance selective adsorption of cationic dye via a large‐pore size effect. The optimized MOF (Bio‐MOF‐100) of large pore size achieved a methylene blue adsorption capacity is high to 443.01 mg/g, which is approximately 2.45 times higher than that of the MOF (Bio‐MOF‐1) before pore regulation. Using a mixed matrix membrane (MMM) strategy, the optimized MOF was mixed with polyvinylidene fluoride (PVDF) to form a membrane. The membrane is not only portable and recyclable, but also inherits the characteristics of MOFs, enabling selective adsorption of cationic dyes. Its maximum adsorption capacity for methylene blue is 141.78 mg/g. These results provide an example for the design and utility of largely‐pore MOFs for targeted pollutants adsorption.