Solvent effect on conformational equilibrium: a Monte Carlo study of 1,3-dichloropropane in carbon tetrachloride Original Research Article

The conformational behavior of the 1,3-dichloropropane (1,3-DCP) molecule in CCl4 solution has been studied by means of Monte Carlo simulations. In a preliminary step, a series of MP2 ab initio calculations on DFT optimized geometries of 1,3-DCP has been carried out in order to construct the conformational energy surface for this molecule. The results obtained indicate that there is a change in the conformational populations of 1,3-DCP on going from the gas phase to solution. The analyses of the role of van der Waals and polarization forces show that the former is the main cause of this conformational change. The structural analysis indicates that the different stabilization energies of the three lowest conformational minima are related to the different accessibilities of solvent molecules to the solute proximities. The usual preferential sampling algorithm and the umbrella sampling method have been adapted to the geometric characteristics of the solute molecule to improve the quality of the results.