Two-in-One Flexible Metal-Organic Framework: One-Step CH Purification via Inverse CH-CH and CH-CO Separations.

Flexible metal-organic frameworks (FMOFs) with "S-shaped" stepped isotherms are stimuli-responsive smart materials that exhibit dynamic structural changes in response to guests, offering intrinsic thermal management and excellent regenerability compared to the classical rigid adsorbents. Herein, a 2-fold interpenetrated 3D flexible MOF (FMOF): is reported whose gate-opening behavior is synchronously intertwined with the pore functionalization strategy, which served as a fascinating tool for simultaneous redressal of highly demanding one-step ethylene (CH) purification via inverse ethane-ethylene (CH/CH) separation (i.e., CH trapping) as well as acetylene-carbon dioxide (CH/CO) separation through one-step sorbent separation technology (OSST). Notably, represents the first FMOF to exhibit inverse CH/CH sorption behavior with outstanding breakthrough separation selectivity of ∼2.3 at room temperature (298 K), accompanied by one-step CH purification from ternary C gas mixtures. Further, it excels in CH/CO separation with a remarkable uptake ratio of ∼18 and high breakthrough selectivity of 8.3. A detailed elucidation into structural dynamics is revealed through X-ray diffraction analysis that manifested the sorbate-induced structural transformation among three distinct phases: as-synthesized (phase-α), activated (phase-β), and gas sorption/gate opened phase (phase-γ). Thus, is a unique industrially compatible two-in-one physisorbent that serves as a multipurpose molecular separator by virtue of reversible flexibility with outstanding separation performances.