Résumé
The adsorption of benzene in the cation containing MOF MIL-141(Cs) was first explored by manometry measurements coupled with Monte Carlo simulations. This joint experimental-modeling approach demonstrates that this solid shows a high affinity for this guest molecule that does not result from a direct interaction between benzene and Cs+ cations in contrast to what is commonly observed in zeolites. This behavior was attributed to a high confinement degree of Cs+ which prevents any cation de-trapping upon adsorption as revealed by Dielectric Relaxation Spectroscopy and Molecular Dynamics simulations. This peculiar adsorption behavior is further discussed when one considers the other alkali extra-framework cations including Li+, Na+, K+ and Rb+.