Host–Guest Interaction Modulation in Porous Coordination Polymers for Inverse Selective CO₂/C₂H₂Separation

Abstract

Abstract Controlling gas sorption by simple pore modification is important in molecular recognition and industrial separation processes. In particular, it is challenging to realize the inverse selectivity, which reduces the adsorption of a high‐affinity gas and increases the adsorption of a low‐affinity gas. Herein, an “opposite action” strategy is demonstrated for boosting CO 2 /C 2 H 2 selectivity in porous coordination polymers (PCPs). A precise steric design of channel pores using an amino group as an additional interacting site enabled the synergetic increase in CO 2 adsorption while suppressing the C 2 H 2 adsorption. Based on this strategy, two new ultramicroporous PCP physisorbents that are isostructural were synthesised. They exhibited the highest CO 2 uptake and CO 2 /C 2 H 2 volume uptake ratio at 298 K. Origin of this specific selectivity was verified by detailed density functional theory calculations. The breakthrough separation performances with remarkable stability and recyclability of both the PCPs render them relevant materials for C 2 H 2 purification from CO 2 /C 2 H 2 mixtures.