Page "Liquid crystal" Paragraph 87

As already described, chiral LC molecules usually give rise to chiral mesophases.

This means that the molecule must possess some form of asymmetry, usually a stereogenic center.

An additional requirement is that the system not be racemic: a mixture of right-and left-handed molecules will cancel the chiral effect.

Due to the cooperative nature of liquid crystal ordering, however, a small amount of chiral dopant in an otherwise achiral mesophase is often enough to select out one domain handedness, making the system overall chiral.