The impact of the multipolar distribution on chiral discrimination in racemates.
This article explores the impact of the multipolar distribution on chiral discrimination in a series of racemic fluids. Discrimination is measured via the difference between the like-like (LL) and the like-unlike (LU) radial distributions in the liquid. We have found previously that the magnitude and orientation of the molecular dipole have a decisive impact on the short-ranged enantiomeric imbalance in racemates. Although quadrupolar and octupolar interactions decrease more rapidly with intermolecular separation, they can be significant at small separations, where enantiomeric imbalances occur. We have carefully selected a number of models in which we isolate the effects of the molecular quadrupole and octupole. We find that discrimination can be greatly enhanced by changes in the quadrupole moments. However, for octupole moments, changes in discrimination are small and some octupoles inhibit discrimination. We identify the quadrupole moment closest to the plane perpendicular to the direction of the molecular dipole as the moment that has the greatest favorable effect on chiral discrimination in racemates. In racemates where this moment is large, we have found differences of up to 40% between the LL and the LU radial distributions.
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Department of Chemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
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