Lifeng Ding

Adsorptive separation by porous materials holds great potential for natural gas purification, yet precise pore regulation for performance optimization still faces difficulties. This study optimizes the pore environment of metal–organic frameworks (MOFs) via alkoxy engineering for efficient natural gas purification. We designed and successfully synthesized three Zr-MOF materials (UiO-68-MeOMe, UiO-68-MeOEt, and UiO-68-MeOPr), systematically investigating the influence of the alkoxy chain length on the MOF pore structure and thus natural gas separation performance. UiO-68-MeOMe has the highest specific surface area. At 298 K and 1 bar, it exhibits a high C3H8 adsorption capacity of 261.8 cm3 g–1. Compared with UiO-68-MeOEt and UiO-68-MeOPr, it exhibits the highest separation potential, a comprehensive metric that integrates both adsorption capacity and selectivity, with values of 7.2 mmol g–1 for C3H8/CH4 and 1.6 mmol g–1 for C2H6/CH4. UiO-68-MeOMe delivers the most outstanding overall performance by optimally balancing the enhanced host-guest interactions against the structural defects arising from alkoxy chain modification. Breakthrough experiments further confirm that UiO-68-MeOMe exhibits good separation performance and shows remarkable cycling stability. Grand Canonical Monte Carlo simulations further verify that UiO-68-MeOMe displays preferential adsorption toward C3H8 and C2H6 over CH4. This work offers a straightforward ligand-engineering route to tailor MOF and adsorbate interactions, guiding the rational design of advanced adsorbents for natural gas purification.

The separation of ethane (C2H6)/ethylene (C2H4) by metal–organic frameworks (MOFs) depends largely on the pore environment. Here we construct a C2H6-selective mesoporous Zr-MOF, NUT-77, using indolo[3,2-b]carbazole-based tetracarboxylate ligands, and then apply post-synthetic linker installation of dicarboxylate linkers for pore space partition (PSP). The resulting NUT-77-Me2BPDC and NUT-77-BPDC-NH2 show increased pore volumes and reduced pore sizes, leading to higher C2H6 uptake and selectivity. At 273 K and 1 bar, the C2H6/C2H4 separation potential (Δq) of NUT-77-Me2BPDC is 122% higher than that of parent NUT-77. Breakthrough experiments confirm the improved dynamic separation. Density functional theory calculations indicate that the installed linkers introduce more C–H···π and hydrogen-bonding sites, strengthening C2H6 affinity. The PSP strategy provides a route for tailoring MOF pore environments to enhance C2H6-selective adsorption in C2H6/C2H4 separation.

The capture of CO2 from flue gas and its subsequent conversion into value-added chemicals is essential for carbon neutrality. Herein, we report NUT-90, an nbo type metal–organic framework assembled from Cu ions and indolo[3,2-b]carbazole (ICZ)-functionalized ligands, which serves this dual function. NUT-90 shows strong affinity for CO2, with an adsorption capacity of 95.1 cm3 g–1 and an IAST selectivity of 114.7 (CO2/N2 = 15/85, 298 K). Density functional theory calculations indicate that ICZ groups and unsaturated Cu sites act cooperatively as Lewis base-acid pairs for CO2 binding. Moreover, as a heterogeneous catalyst at 328 K, NUT-90 converts CO2 from flue gas with bromopropylene oxide into cyclic carbonate, achieving up to 99% yield and maintaining activity over four cycles. This work demonstrates NUT-90 as a viable material platform for integrated CO2 capture and utilization.

Photoresponsive porous liquids (PPLs) are emerging as promising materials for light-regulated gas adsorption, while precise control over their photoresponsiveness remains challenging. Herein, we report precise modulation of the PPLs’ photoresponsiveness by azobenzene orientation engineering in the hosts. Two positional isomers, 4-phenylazopyridine (4-Azo) and 3-phenylazopyridine (3-Azo), are anchored onto the axial metal sites of a sulfonate-containing metal−organic cage (MOC), affording porous hosts MOC-4-Azo and MOC-3-Azo with distinct azobenzene orientation. Considering the anionic nature of hosts, a polyethylene glycol-based ionic liquid (IL-Br) is designed as a sterically hindered solvent, yielding two PPLs, PL-4-Azo and PL-3-Azo. Notably, PL-4-Azo shows a 49.5% change in propylene uptake under light irradiation, whereas PL-3-Azo shows only a 1.0% variation. This pronounced difference originates from the different spatial orientations of azobenzene, which influence its ability to regulate internal and external cavities upon isomerization. This study may provide insights into precise design of stimuli-responsive materials for various applications.

Organic semiconductors emerge as promising chemiresistive gas-sensing materials, benefiting from their high selectivity and sensitivity toward various gases. However, these materials usually work at room temperature; thus, the adsorption of water vapor is usually unavoidable and produces interfering signals, which significantly hinders the detection of nitric dioxide (NO₂) at the parts per billion (ppb) level and their practical application. In this work, side-chain engineering was applied to ion-in-conjugation (IIC) polymers for addressing moisture interference in NO₂ sensing. By controlling the condensing precursors, different numbers of methyl groups (n = 0/1/2) were introduced on the phenyl ring. The side-chain engineering could enable the polymers to stably detect NO₂ even at relative humidity levels ranging from 0 to 75% at the parts per billion level. Specifically, the p-PTS (n = 1)-based sensor shows only a 10.3% decrease in response to NO₂ at room temperature without requiring heating or hydrophobic layer coverage. Moreover, these polymers demonstrate the highest charge transfer after adsorbing NO₂ compared to other interfering gases, which endow the sensors with high selectivity for NO₂. Theoretical calculations reveal that the introduction of methyl groups improves the planarity of the polymer backbone upon water adsorption, which enhances the charge transfer following NO₂ adsorption. At the same time, the presence of methyl groups prevents water molecules from accessing the adsorption sites and provides an inherent moisture resistance. These results offer an approach for creating high-performance NO₂ sensors with built-in moisture resistance and establish a foundation for future use in more challenging environmental conditions.

Porous liquids (PLs), integrating porous hosts into flowing liquids through intermolecular interactions, attract significant attention, while their controlled synthesis remains challenging. Here we report a controllable in-situ transformation strategy to fabricate distinct types of PLs from the same supramolecular framework (SMF). Two isomorphic polyethylene-glycol-based ionic liquids, IL-Br and IL-NTf₂, differing only in anions, exhibit contrasting electrostatic interactions with the SMF. Strong attraction between IL-Br and the SMF disrupts the ionic bonds within the framework, yielding a type II PL, PL2(SMF-Br), while electrostatic repulsion in IL-NTf₂ preserves the framework, producing a type III PL, PL3(SMF-NTf₂). These tailored host–solvent interactions endow PL2(SMF-Br) with over twice the CO₂ uptake and photoresponsivity of its counterpart, as well as record-high CO₂ capacity among reported type II PLs. In this work, we establish a general strategy for tunable PL construction through electrostatically guided host–solvent design.

The persistent challenge in catalysis lies in reconciling the high activity of homogeneous systems and the easy separation of heterogeneous catalysts. Inspired by biological photoadaptation, we report azobenzene-functionalized metal-organic polyhedra (MOPs) that achieve a photoswitchable transformation between homogeneous and heterogeneous catalysis via light-triggered trans-cis isomerization. The photoswitchable catalysts were fabricated by grafting azobenzene moieties on Rh₂ paddlewheel axial sites in RhMOP. Visible light stabilizes the trans isomer, yielding homogeneous catalysis through optimized solvation and weakened intermolecular forces, while UV-induced cis isomerization triggers a catalyst precipitate via unfavorable solvation and enhanced interactions. This phase switching creates a 52% yield differential in CO₂ cycloaddition with epichlorohydrin, governed by phase-dependent active site accessibility and different steric effects derived from isomerization. The catalyst retains activity over light-regulated cycles and adapts to diverse substrates and photoswitchable catalysts. This study may provide a promising approach to bridge the gap between homogeneous and heterogeneous catalysis.

We developed a GNN-based workflow to identify macrocycles and cages across the Cambridge Structural Database. This approach expanded the former Macrocycles and Cages Database to 26 860 entries, including 12 257 items missed by rule-based searches.

This study demonstrates the rational synthesis of Pd dual-atom catalysts via molecular precursor (Pd ₄ L ₄ ) engineering for selective hydrogenation.