Molecular-Rotor-Engineered Metal-Organic Frameworks with Various Interpenetrated Degrees/Modes Featuring Tunable...

Efficient separation of challenging acetylene/ethylene (C₂H₂/C₂H₄) and acetylene/carbon dioxide (C₂H₂/CO₂) 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 C₂H₂ uptake (73.9/75.8 cm³ 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 C₂H₂ separation performance from binary/ternary mixtures and achieve one-step purification of C₂H₄ (>99.9%) from C₂H₂/CO₂/C₂H₄ (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 C₂H₂/C₂H₄ and C₂H₂/CO₂ 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.