Covalent organic framework shows high isobutene adsorption selectivity from C4 hydrocarbons: Mechanism of interpenetration isomerism and pedal motion

Adsorption and separation of C4 hydrocarbons are crucial steps in petrochemical processes. Employment of porous materials for enhancing the separation efficiency have paid much attention. Covalent-organic frameworks of diamond-topology, dia-COFs, often exhibit unique structural properties such as interpenetration isomerism and pedal motion. Herein, in order to get a deep insight into the structure-performance correlation of such dia-COFs, a series of dia-COF materials have been proposed and theoretically investigated on the C4 separation. It is found that these dia-COFs display an excellent adsorption and separation property towards isobutene with respect to other C4 hydrocarbons (i.e., 1,3-butadiene, 1-butene, 2-cis-butene, 2-trans-butene, isobutane and n-butane). What's more, the correlation between the topology parameters and experimental synthesis feasibility has been established for COF-300 (dia-cN), and the unreported COF-300 (dia-c3) is predicted to be experimentally feasible synthesized. Our findings not only provide a deep insight into the mechanism of topology characteristics of dia-COFs on C4 adsorption and separation properties but also guide the design and synthesis of novel highly-effective porous materials.