Temperature-dependent molecular sieving of fluorinated propane/propylene mixtures by a flexible-robust metal-organic framework

The electronics industry necessitates highly selective adsorption separation of hexafluoropropylene (C₃F₆) from perfluoropropane (C₃F₈), which poses a challenge due to their similar physiochemical properties. In this work, we present a microporous flexible-robust metal-organic framework (Ca-tcpb) with thermoregulatory gate opening, a rare phenomenon that allows tunable sieving of C₃F₈/C₃F₆. Remarkably, the temperature-dependent adsorption behavior enhances the discrimination between the larger C₃F₈ and the smaller C₃F₆, resulting in unprecedented C₃F₆/C₃F₈ selectivity (over 10,000) compared to other well-known porous materials at an optimal temperature (298 K). Dynamic breakthrough experiments demonstrate that high-purity C₃F₈ (over 99.999%) could be obtained from a C₃F₆/C₃F₈ (10:90) mixture under ambient conditions. The unique attributes of this material encompass exceptional adsorption selectivity, remarkable structural stability, and outstanding separation performance, positioning it as a highly promising candidate for C₃F₆/C₃F₈ separation. Single-crystal structural analysis of C₃F₆-loaded Ca-tcpb and theoretical calculations elucidate the host-guest interaction via multiple intermolecular interactions.