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 (CF) from perfluoropropane (CF), 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 CF/CF. Remarkably, the temperature-dependent adsorption behavior enhances the discrimination between the larger CF and the smaller CF, resulting in unprecedented CF/CF selectivity (over 10,000) compared to other well-known porous materials at an optimal temperature (298 K). Dynamic breakthrough experiments demonstrate that high-purity CF (over 99.999%) could be obtained from a CF/CF (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 CF/CF separation. Single-crystal structural analysis of CF-loaded Ca-tcpb and theoretical calculations elucidate the host-guest interaction via multiple intermolecular interactions.