Researchers Unveil Unique Pillar-Cage Framework with J28 Structure

A team led by Prof. Wu Mingyan at the Fujian Institute of Research on the Structure of Matter, part of the Chinese Academy of Sciences, has successfully synthesized a novel pillar-cage fluorinated hybrid porous framework known as TIFSIX-Cu-J. This innovative framework features a rare crystalline structure described as a quasi-Johnson solid J28, as detailed in their recent publication in the journal Chem on November 5, 2025.

The researchers employed a bottom-up, self-assembly approach to create TIFSIX-Cu-J, utilizing geometrical elements shaped like quadrangles and isosceles triangles. During the synthesis, TIFSIX-Cu-J underwent a heat-triggered transformation, changing the J28 cage into a distorted square orthobicupola structure. This transformation was thoroughly analyzed through single-crystal-to-single-crystal (SC-SC) transitions and bulk crystalline powder X-ray diffraction techniques.

This study not only highlights the unique properties of TIFSIX-Cu-J but also demonstrates the potential for synthesizing isomorphic crystals such as SIFSIX-Cu-J and ZrFSIX-Cu-J. The self-assembly method has shown promising results in facilitating in-situ SC-SC structural transformations.

In terms of performance, TIFSIX-Cu-J1, a variation of the original framework, exhibited an impressive adsorption capacity for C3H4 of 140.5 cm3·g-1. The difference in adsorption amounts between C3H4 and C3H6 increased significantly, ranging from 19.6 cm3·g-1 to 34.8 cm3·g-1. Notably, TIFSIX-Cu-J1 also demonstrated a greater C3H4/C3H6 IAST selectivity compared to TIFSIX-Cu-J.

In breakthrough experiments, a packed column of TIFSIX-Cu-J1 achieved a production rate for C3H6 approximately twenty times higher than that of TIFSIX-Cu-J. Theoretical calculations indicated that the unique pore surface of the quasi-Johnson solid J28 cavity in TIFSIX-Cu-J1 facilitates the preferential capture of C3H4 over C3H6. This characteristic enhances the selective separation of these gases, which is crucial for energy-efficient purification processes.

The findings of this research provide significant insights into the systematic design and synthesis of novel pillar-cage fluorinated hybrid porous frameworks. The study underscores the effectiveness of the bottom-up, self-assembly approach in constructing advanced three-dimensional architectures with selective separation properties, paving the way for innovations in gas purification technologies.

For further details, refer to the study by Cheng Chen et al., titled “Pillar-cage fluorinated hybrid porous frameworks featuring quasi-Johnson solid J28,” published in Chem (2025). DOI: 10.1016/j.chempr.2025.102696.