Precise Pore Engineering of a Pillar-Layered MOF via the Dual-Ligand Strategy for C ₂ H ₂ /CO ₂ Separation

The efficient separation of acetylene (C₂H₂) and carbon dioxide (CO₂) is of major practical importance but remains difficult because of their analogous physical properties. The dual-ligand strategy provides an effective approach to tailor pore structure and chemical microenvironments for enhanced functionality. Nevertheless, the structural controllability of metal-organic frameworks (MOFs) assembled from tetracarboxylic acids and azole ligands remains challenging. Herein, we report a unique pillar-layered MOF, Zn-TCPB-dmtrz, constructed based on a dual-ligand strategy, demonstrating the efficient separation of C₂H₂/CO₂. The coordination of different ligands generates 1D [Zn₄N₆]_<i>n</i> chains, which function as pillars to interconnect 2D layers into a rare pillar-layered structure. The combination of abundant N/O sites and hydrophobic pore environment achieves high C₂H₂ adsorption capacity and excellent C₂H₂/CO₂ separation ability. Furthermore, its relatively low C₂H₂ <i>Q</i>_st, competitive thermal stability, and recyclability underscore its practicality for C₂H₂/CO₂ separation. This study enriches the structural diversity of pillar-layered MOFs and demonstrates the controllable dual-ligand strategy based on tetracarboxylic acid and dmtrz ligands for advanced gas separation.