Conformational free energies of 1,2-dichloroethane in nanoconfined methanol.
Monte Carlo simulations have been used to construct free energy surfaces of 1,2-dichloroethane dissolved in methanol confined in hydrophobic spherical cavities of varying size (10-15 A) and solution density (0.6-0.79 g/cm3). The free energy surfaces are functions of two variables: the (center-of-mass) distance from the cavity wall of 1,2-dichloroethane and the Cl-C-C-Cl dihedral angle. Umbrella sampling and the weighted histogram analysis method were used to obtain accurate results for the free energy in these two degrees of freedom. Our results indicate that the conformational equilibrium and the barrier to internal rotation of the 1,2-dichloroethane depend on the position in the cavity. The results are discussed in the context of the solvent density, orientational distributions, and packing effects.
Gomez
J A
JA
Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
Tucker
Ashley K
AK
Shepherd
Tricia D
TD
Thompson
Ward H
WH