Chiral discrimination in solutions and in Langmuir monolayers

In this paper we examine theoretically the chiral discrimination of molecules with a single chiral center. We propose a definition of the chiral discrimination parameter 4 in terms of the difference between the second virial coefficient of pure enantiomers and their racemic mixture. This parameter enters in the equation of state of racemic mixtures and will determine their phase diagrams. We calculate then the chiral discrimination between D- and L-alanine using a Monte Carlo simulation to average over 11 molecular degrees of freedom at fixed intermolecular distances using the CHARMM energy function. The discrimination is found to slightly favor homochirality and mainly comes from steric hindrance at short distances. We also perform a direct integration for rigid chiral tetrahedron-shaped molecules