Evidence of Amine–CO 2 Interactions in Two Pillared‐Layer MOFs Probed by X‐ray Crystallography

Two pillared‐layer metal–organic frameworks (MOFs; PMOF‐55 and NH 2 ‐PMOF‐55) based on 1,2,4‐triazole and terephthalic acid (bdc)/NH 2 ‐bdc ligands were assembled and display framework stabilities, to a certain degree, in both acid/alkaline solutions and toward water. They exhibit high CO 2 uptakes and selective CO 2 /N 2 adsorption capacities, with CO 2 /N 2 selectivity in the range of 24–27, as calculated by the ideal adsorbed solution theory method. More remarkably, the site and interactions between the host network and the CO 2 molecules were investigated by single‐crystal X‐ray diffraction, which showed that the main interaction between the CO 2 molecules and PMOF‐55 is due to multipoint supramolecular interactions of CH⋅⋅⋅O, C⋅⋅⋅O, and O⋅⋅⋅O. Amino functional groups were shown to enhance the CO 2 adsorption and identified as strong adsorption sites for CO 2 by X‐ray crystallography.