A Lewis basic site rich metal–organic framework featuring a hydrogen-bonded acetylene nano-trap for the efficient separation of C2H2/CO2†

The physical separation of C₂H₂ from CO₂ on metal–organic frameworks (MOFs) has received a substantial amount of research interest due to its advantages of simplicity, security, and energy efficiency. However, the exploitation of ideal MOF adsorbents for C₂H₂/CO₂ separation remains a challenging task due to their similar physical properties and molecular sizes. Herein, we report a unique C₂H₂ nano-trap constructed using accessible oxygen and nitrogen sites, which exhibits energetic favorability toward C₂H₂ molecules. This material exhibits a good acetylene capacity of 55.31 cm³ g⁻¹ and high C₂H₂/CO₂ selectivity of 7.0 under ambient conditions. We have combined in situ IR spectroscopy and in-depth theoretical calculations to unravel the synergistic interactions driven by the high density of accessible oxygen and nitrogen sites. Furthermore, dynamic breakthrough experiments confirmed the capability of TUTJ-201Ni for the separation of binary C₂H₂/CO₂ mixtures. This study on Ni-based MOFs will enrich Lewis basic site rich MOFs for gas adsorption and separation applications.