Topology-DirectedCage Engineering in MOFs for EfficientC₂H₂/CO₂/C₂H₄ Separation

Abstract

Cage-based porous materials, leveraging their unique “confined windows–expanded cavities” synergistic architecture, have demonstrated remarkable advantages in the field of gas adsorption and separation. This study presents a topology-directed in situ assembly strategy that successfully constructs metal–organic frameworks with tailored pore structures. Using the distinctive cage-channel soc topological frameworks as a template, by innovatively reversing the roles of traditional nodes and linkers, we employed the conformationally flexible hexa-pyridine ligands as six-connected nodes and utilized undercoordinated Cu²⁺ as five-connected linkers, in combination with halogen anions (F^–, Cl^–, and Br^–) as two-connected topological “blockers”, resulting in the successful synthesis of three MOF materials (LNU-H1, LNU-H2, and LNU-H3) featuring an unprecedented jcq topological network. These materials exhibit a unique “confined window–expanded cavity” synergistic structure, achieving complete closure of linear channels. Notably, LNU-H1 demonstrated exceptional performance in the separation of ternary C₂H₂/CO₂/C₂H₄ gas mixtures, as validated by dynamic breakthrough experiments under industrially relevant conditions. This study not only confirms the effectiveness of the topology-directed pore engineering approach but also provides new insights into the development of advanced, energy-efficient functional materials for gas separation applications.