Temperature-Responsive Molecular Sieving of Fluorinated Propylene and Propane via a Flexible Metal–Organic Framework with High-Density Open Metal Sites

The development of porous materials capable of achieving efficient separation of hexafluoropropylene (C₃F₆) and octafluoropropane (C₃F₈) remains a challenge due to their nearly identical physical properties and stringent purity demands in industrial applications. Herein, we report a flexible, quasi-one-dimensional coordination polymer, Mn-dhbq ([Mn(dhbq)(H₂O)₂]_n, where dhbq = 2,5-dihydroxy-1,4-benzoquinone), featuring a high density of open metal sites and a temperature-responsive swelling architecture. This unique combination enables dynamic molecular sieving through selective binding of C₃F₆ while effectively excluding C₃F₈. At 298 K, dynamic breakthrough experiments with a 10:90 (v/v) C₃F₆/C₃F₈ gas mixture yielded high-purity C₃F₈ (≥99.999%) over 190 L/kg. Mn-dhbq demonstrated remarkable thermal, chemical, and hydrothermal stability, along with scalability for 100-gram-scale synthesis and moldability into industrially relevant pellets using organic binders. The combination of high stability, scalability, and temperature-responsive selectivity highlights Mn-dhbq as a promising candidate for energy-efficient separation of fluorinated gases, addressing critical purification challenges in the semiconductor and electronics industries.