Structural insight into benzene vs. cyclohexane adsorption by the covalent organic framework COF-300: the role of host-guest interactions an

Benzene (BEN) / cyclohexane (CH) separation is a challenging procedure in the chemical industry. Due to the 0.6 K difference in their b.p. conventional distillation is unviable. Adsorption-based separation by porous materials is less costly but needs a selectivity vs. diffusion kinetics trade-off. In this context we studied the known covalent organic framework (COF) [(TAM)(BDA)] (COF-300, TAM = tetrakis(4- aminophenyl)methane, BDA = terephthaldehyde) [1]. BEN and CH static adsorption showed step-like isotherms, typical of flexible pores, with higher adsorption capacity for BEN; dynamic adsorption unveiled a higher BEN retention time, suggesting stronger host-BEN interactions. High-resolution PXRD in situ-dosing BEN or CH at given vapour pressures will allow disclosing the purported flexibility and the BEN/CH preferential adsorption sites. This will help rationalizing the role of flexibility and host-guest interactions in BEN and CH adsorption for COF-300 and new-generation adsorbents.