One Porous Metal-Organic Framework Containing Multinuclear Clusters and Functional Groups for Purification of...

For the critical yet challenging industrial processes of the selective removal of trace acetylene (C₂H₂) from ethylene (C₂H₄) and the separation of C₂H₂ from carbon dioxide (CO₂), we herein report the rational design and synthesis of a novel hydroxy-functionalized Zn(II)-based metal-organic framework, Zn-btb-OH, constructed from a custom-designed ligand, 1,3,5-tri(4-carboxyphenyl)benzene (H₃btb-OH). Zn-btb-OH features a unique interwoven architecture comprising open channels with flattened cage-like cavities and accessible -OH groups and demonstrates a high C₂H₂ adsorption capacity (60.1 cm³ g^-1 at 298 K and 100 kPa) and exhibits preferential adsorption for C₂H₂ over C₂H₄ and CO₂. Ideal Adsorbed Solution Theory (IAST) selectivity calculations reveal values of 2.2 and 4.4 for equimolar C₂H₂/C₂H₄ and C₂H₂/CO₂ mixtures at 298 K, respectively. Dynamic breakthrough experiments confirm its excellent practical separation performance, achieving the complete purification of C₂H₄ from C₂H₂ and efficient capture of C₂H₂ from CO₂. Grand Canonical Monte Carlo simulations elucidate that the superior affinity for C₂H₂ originates from multiple specific host-guest interactions, including C-H···π and C-H···O contacts.