Complete Utilization of Ligand Coordination Sites in Co-MOF for C₂H₂/CO₂ Separation

Separating acetylene (C₂H₂) and carbon dioxide (CO₂) is challenging due to their similar properties. Metal-organic frameworks (MOFs) are promising adsorbents for this separation, and the discovery of new structures is vital for advancing MOF applications. Herein, we report a two-dimensional Co-MOF, [Co(H₂O)₂(DCBA)_0.5] (UPC-117), with 4″,6'-diamino-5',5″-bis(4-carboxyphenyl)-[1,1':3',1″:3″,1‴-quaterphenyl]-4,4‴-dicarboxylic acid (H₄DCBA) as ligand. It is rarely observed that all four carboxyl groups and two amino groups of H₄DCBA are involved in coordination, affording one-dimensional rhombic channels of 4.0 Å × 10.4 Å in UPC-117. The exposed open metal sites after activation endow UPC-117 with an excellent C₂H₂/CO₂ separation performance, which is evidenced by static adsorption isotherms, dynamic breakthrough curves, and theoretical calculations.