Yingzhi He, Guangzu Xiong, Wenlei Yang, Yunjia Jiang, Jianbo Hu, Lingyao Wang*, Chaoqun Bian*, Yuanbin Zhang*

Cite this article: Chin. J. Struct. Chem., 2026, 45(8), 100942. DOI: 10.1016/j.cjsc.2026.100942

Publication date: August 1, 2026

Keywords: Ultramicroporous material; Hydrogen-bonded organic framework (HOF); C₂H₂/CO₂ separation; Sieving; Gas adsorption

ABSTRACT

The separation of acetylene (C2H2) from carbon dioxide (CO2) is of great importance in industrial chemical processes but remains challenging due to their similar physical properties. Hydrogen-bonded organic frameworks (HOFs) have emerged as promising adsorbents, yet balancing their structural stability with separation performance requires further optimization. Herein, we report two ionic metal-hybrid HOFs (ZNU-29 and ZNU-30) constructed via ligand modulation and metallization strategies. ZNU-30 features one-dimensional ultramicroporous channels (2.66 × 3.66 Å2) lined with H2PO4- groups and electron-rich pyridine rings, creating a confined pore environment that combines molecular sieving and electrostatic interactions. At 298 K, ZNU-30 exhibits high C2H2 uptake (63.7 cm3/g) and significantly suppressed CO2 adsorption (5.6 cm3/g), leading to an exceptional ideal adsorbed solution theory (IAST) selectivity of 121 for an equimolar C2H2/CO2 mixture. Dynamic breakthrough experiments confirm its excellent practical separation capability. Density functional theory calculations reveal that the superior performance originates from stronger binding affinity and lower diffusion barriers for C2H2 compared to CO2, enabled by the precisely tailored pore geometry and electronegative pore environment. This work offers an effective strategy for designing stable and highly selective metal-hybrid HOFs for challenging gas separations.