Solvent effect on conformational equilibrium: A Monte Carlo study of 1,2-dichloroethane in carbon tetrachloride

The Monte Carlo method is applied to the study of the dilute solution of 1,2-dichloroethane in CCl4 in order to explain the conformational change of the solute that is inferred from dipole moment measurements and predicted by reference interaction site model calculations. Several simulations are performed employing different types of solute-solvent interaction potentials. The results show that the conformational change can be correctly explained only when the interaction between the dipole moment of solute and the dipole moment induced in the solvent molecules is considered. This polarization effect is introduced in the calculation of the energy of each solute-solvent dimer. The results obtained contrast with the overestimations due to the reaction field theory. It is also found that a potential model without net charges in the Lennard-Jones interaction sites does not cause any solute alteration and that the addition to these sites of the corresponding net charges yields a very small conformational change in the opposite sense. Additional energetic and structural data is included for the polarization model simulation. (C) 1996 American Institute of Physics.