Computer-aided design of interpenetrated tetrahydrofuran-functionalized 3D covalent organic frameworks for CO ₂ capture

Using computer-aided design, several interpenetrated imine-linked 3D covalent organic frameworks with diamondoid structures were assembled from tetrakis-4-formylphenylsilane as the tetrahedral node, and 3R,4R- diaminotetrahydrofuran as the link. Subsequently, the adsorption capacity of CO ₂ in each framework was predicted using grand canonical Monte Carlo simulations. At ambient conditions, the 4-fold interpenetrated framework, with disrotatory orientation of the tetrahedral nodes and diaxial conformation of the linker, displayed the highest adsorption capacity (∼4.6 mmol/g). At lower pressure, the more stable 5-fold interpenetrated framework showed higher uptake due to stronger interaction of CO ₂ with the framework. The contribution of framework charges to CO ₂ uptake was found to increase as the pore size decreases. The effect of functional group was further explored by replacing the ether oxygen with the CH ₂ group. Although no change was observed in the 1-fold framework, the CO ₂ capacity at 1 bar decreased by ∼32% in the 5-fold interpenetrated framework. This work highlights the need for a synergistic effect of a narrow pore size and a high density of ether-oxygen groups for high-capacity CO ₂ adsorption.