Pillar-cage fluorinated hybrid porous frameworks featuring quasi-Johnson solid J28

Abstract

Adsorptive separation process based on porous materials is widely employed in various separation scenarios owing to its mild operating conditions and energy-efficient characteristics. In this study, we present a bottom-up, self-assembly approach to synthesize a novel pillar-cage fluorinated hybrid porous framework (TIFSIX-Cu-J), which exhibits a rare crystalline quasi-Johnson solid J₂₈ structure. Notably, this material undergoes heat-triggered structural transformation, resulting in a new distorted square orthobicupola structure (TIFSIX-Cu-J1). The structural changes were elucidated through detailed analysis of the single-crystal-to-single-crystal transformation and bulk crystalline powder X-ray diffraction. The resulting framework demonstrates significantly enhanced performance in separating trace propyne from propylene. In situ breakthrough experiments show that the TIFSIX-Cu-J1-packed column can achieve approximately 20-fold higher C₃H₆ productivity (≥99.95%) compared with TIFSIX-Cu-J at 298 K and 1 bar. This study presents the first successful fabrication of crystalline square orthobicupola frameworks demonstrating in situ structural transformation characteristics, which exhibit significant potential for energy-efficient gas purification applications.