Stepwise pillar-ligand fluorination strategy within interpenetrated metal–organic frameworks for efficient C2H2/CO2 separation.

[Display omitted] • The insertion of pillar ligands of UPC-190 series MOFs can lead to changes in the interpenetrating structure. The degree of interpenetration can be managed by introducing different pillars. • Theoretical calculations demonstrate that the fluorine atom on pillar ligands is an effective interaction site for C 2 H 2 molecules. This means that fluorine atoms can act as active sites that interact with C 2 H 2 molecules, thereby influencing their adsorption behavior. • The formation of interpenetrating structures and the stepwise fluorination strategy gradually improve the IAST selectivity and C 2 H 2 uptake of the sample. This strategy proves guidance for designing MOFs for challenging gas separations. The efficient separation of C 2 H 2 /CO 2 possesses great commercial and research value and remains challenging due to their similar molecular sizes and physical properties. Functionalization is a powerful strategy for precisely regulating the pore environment of porous adsorbents, notably metal–organic frameworks (MOFs), for recognizing target molecules. Here, we construct three interpenetrated MOFs using a stepwise fluorinated pillar-ligand strategy. Interestingly, the degree of interpenetration can be managed by introducing different pillars. The unique interpenetrating structure cooperates with fluorine-rich pore environment significantly improves the C 2 H 2 uptake and the C 2 H 2 /CO 2 separation selectivity. The optimized difluorine-functionalized UPC-193 exhibits the highest C 2 H 2 adsorption capacity (80.45 cm3/g) and separation efficiency (C 2 H 2 /CO 2 uptake ratio of 1.9) among UPC-190 systems at ambient conditions. Ideal adsorbed solution theory (IAST) calculations, molecular modeling studies, and breakthrough experiments comprehensively demonstrate that UPC-193 is an effective MOF adsorbent for equimolar C 2 H 2 /CO 2 separation. The stepwise pillar-ligand fluorination strategy proves to be an effective approach to extend the functionality of MOFs for challenging gas separations. [ABSTRACT FROM AUTHOR]