An atomistic view on the uptake of aromatic compounds by cyclodextrin immobilized on mesoporous silica

Abstract

The effect of immobilized $$\upbeta$$ β -cyclodextrin (bCD) molecules inside a mesoporous silica support on the uptake of benzene and p-nitrophenol from aqueous solution was investigated using all-atom molecular dynamics (MD) simulations. The calculated adsorption isotherms are discussed with respect to the free energies of binding for a 1:1 complex of bCD and the aromatic guest molecule. The adsorption capacity of the bCD-containing material significantly exceeds the amount corresponding to a 1:1 binding scenario, in agreement with experimental observations. Beside the formation of 1:2 and, to a lesser extent, 1:3 host:guest complexes, also host–host interactions on the surface as well as more unspecific host–guest interactions govern the adsorption process. The demonstrated feasibility of classical all-atom MD simulations to calculate liquid phase adsorption isotherms paves the way to a molecular interpretation of experimental data that are too complex to be described by empirical models.

Axial Diffusion in Liquid-Saturated Cylindrical Silica Pore Models

“…The possible occurrence of deprotonated silanol groups on the surface was not considered. For the TMS surface group, GAFF was used following earlier work. ,, …”

“…For the TMS surface group, GAFF was used following earlier work. 87,89,90 The pore simulations were prepared using the open-source PoreSim 91 python package, which generates a simulation directory structure as well as scripts that automatize the insertion of molecules into the simulation box containing the pore. The simulation suite GROMACS 2019.6 92,93 was used for all simulations.…”