Bottom-up computational design of shape-selective organic macrocycles for humid CO2 capture

Abstract

The capture of CO₂ emissions using porous solids is challenging because polar water molecules bind more strongly in most materials than non-polar CO₂ molecules. This is a challenge for both flue gas capture and for direct air capture alike. Here we develop a bottom-up computational screening workflow to calculate the binding energy of 27,446 diverse molecular fragments with both CO₂ and water. Most molecules favour water binding, but bent, clip-like aromatic molecules exhibit potential for the desired reverse selectivity. This suggests that aromatic macrocycles with specific shapes can promote multiple weak π–π interactions with CO₂ that surpass stronger but less numerous dipole–π interactions with water. We synthesize two water- and acid-stable molecular prisms with triangular and square geometries, as suggested by computation. Experiments confirm that the CO₂ capture capacity of these prisms is unaffected by high relative humidity, surpassing the performance of benchmark commercial porous materials.