Adaptive Corner‐Pocket Channels in a Metal‐Organic Framework for Acetylene Ultra‐Fast Diffusion and Storage

ABSTRACT Ultra‐microporous molecular sieving materials offer exceptional size‐ and shape‐selective gas separation, yet their practical use is often limited by slow diffusion kinetics and low adsorption capacities. Here, we report a low‐cost manganese‐based metal‐organic framework (MOF), Mn‐dcbp, featuring an adaptive “corner‐pocket” channel structure. While retaining C 2 H 2 /C 2 H 4 sieving selectivity, the material successfully integrates a high acetylene (C 2 H 2 ) uptake (126.3 cm 3 /cm 3 ) with ultrafast diffusion kinetics (k = 0.01863 s −1 ). In situ single‐crystal x‐ray diffraction reveals a sub‐angstrom‐level structural adaptation mechanism induced by C 2 H 2 , leading to ordered, high‐density packing of C 2 H 2 within the channels and achieving a record storage density of 1.02 g/mL. Strong host–guest interactions enable the material to maintain excellent C 2 H 2 adsorption capacity (110.6 cm 3 /cm 3 ) even at elevated temperatures (75 °C), while also demonstrating superior separation performance for C 2 H 2 /C 2 H 4 and C 2 H 2 /CO 2 gas mixtures. Furthermore, Mn‐dcbp can be produced on a large scale via an environmentally friendly route and exhibits excellent, water, thermal, and cycling stability, which is crucial for potential industrial implementation.