Increased CO 2 /N 2 selectivity by stepwise fluorination in isoreticular ultramicroporous metal-organic frameworks.

Exploration of porous adsorbents with high CO 2 /N 2 selectivity is of great significance for reducing CO 2 content in the atmosphere. In this study, a series of isoreticular ultramicroporous fluorinated metal-organic frameworks (MOFs) were prepared to explore the benefits of fluorinated ultramicropores in improving CO 2 /N 2 selectivity. Gas adsorption measurements revealed that the increase in the number of fluorine atoms in a ligand molecule leads to the increased CO 2 uptakes and CO 2 /N 2 selectivity. Theoretical calculations indicate that the interaction between the fluorine atoms and adsorbed CO 2 molecules enhances the CO 2 -philicity, offering useful insight into the improvement of CO 2 /N 2 selectivity in isoreticular frameworks.