An Extraordinary Stable and Ultramicroporous Y-MOF for Propylene/Ethylene Separation and Knoevenagel Condensation

Rare-earth metal–organic frameworks (RE-MOFs) have garnered significant attention in materials chemistry owing to their structural diversity and programmable functionality. The judicious selection of organic ligands plays a vital role in constructing novel RE-MOF architectures. JLU-MOF207 was constructed by using [Y4(μ3-O)2(HCOO)2] secondary building units (SBUs) with a methanetetrakis(p-biphenylcarboxylate) (H4MTBC) ligand and possessed an unprecedented (4, 4, 12) connected topology. Notably, the interweaving of helical Y–O chains and H4MTBC ligands within JLU-MOF207 generates ultramicroporous channels (∼ 5 Å diameter), which are decorated with exposed yttrium sites and oxygen-rich environments. JLU-MOF207 exhibits excellent acid, base, solvent, and thermal stability. Due to its confined spaces, multiple open yttrium sites, and oxygen donors in the helical ultramicroporous channels, JLU-MOF207 displays pronounced C3H6/C2H4 separation selectivity (9.6 at 298 K) and excellent production of 2-benzylidenemalononitrile with 99% yield from benzaldehyde and malononitrile at ambient temperature. The recorded turnover number (TON = 660) and turnover frequency (TOF = 5.5 min–1) surpass those of most reported MOF-based catalysts for Knoevenagel condensation. This study demonstrates that rational ligand design enables the construction of Y-MOF with dual functionality, providing new perspectives for developing multifunctional porous materials in gas separation and heterogeneous catalysis applications.