Molecular‐Rotor‐Engineered Metal–Organic Frameworks with Various Interpenetrated Degrees/Modes Featuring Tunable Porosity/Stability for Binary/Ternary C ₂ H ₂ /CO ₂ /C ₂ H ₄ Separation

Abstract

Abstract Efficient separation of challenging acetylene/ethylene (C 2 H 2 /C 2 H 4 ) and acetylene/carbon dioxide (C 2 H 2 /CO 2 ) mixtures is crucial for the chemical industry. Interpenetrated metal–organic frameworks (MOFs) hold significant promise for separating complex gas mixtures but often face a trade‐off between porosity and stability. Herein, three different entangled degrees and modes of MOFs, namely Ni‐dcpp‐bpb , Ni‐dcpp‐bpn , and Ni‐dcpp‐bpan , were yielded by the crystal engineering strategy using molecular‐rotor‐based co‐ligands (benzene, naphthalene, and anthracene groups) to systematically modulate their porosity and stability. As expected, the stable Ni‐dcpp‐bpb / Ni‐dcpp‐bpn achieve enhanced porosity (27.2%/32.1%) and improved C 2 H 2 uptake (73.9/75.8 cm 3 g −1 , 298 K, 100 kPa). Interestingly, Ni‐dcpp‐bpan exhibits the unique rotor‐driven gating effect with free bpan ligands, facilitating the pressure‐dependent switching between nonporous (10.8%) and open states at 195 K. Breakthrough experiments confirm excellent C 2 H 2 separation performance from binary/ternary mixtures and achieve one‐step purification of C 2 H 4 (>99.9%) from C 2 H 2 /CO 2 /C 2 H 4 (1/9/90, v/v/v) mixture with a new benchmark productivity of 396.9 L kg −1 ( Ni‐dcpp‐bpb ). Theoretical calculations and in situ IR spectra reveal that C 2 H 2 /C 2 H 4 and C 2 H 2 /CO 2 separation are primarily governed by the abundant C─H⋯O/N and C─H⋯π interactions. This study establishes a molecular‐rotor‐engineered approach to precisely modulate interpenetration in MOFs and offers a robust platform for high‐performance gas purification.