Chiral differentiation of limonene in chiral nematic liquid crystals

Chirality is of great importance in physical and biological systems. It helps differentiate chemical reactions and physical processes. It was reported that the diffusion of mesogenic chiral guests in chiral nematic liquid crystal hosts profoundly depends on the chirality of the guest and host molecules. When the guest and host molecules have the same handedness, the diffusion is much faster than that when the guest and host molecules have the opposite handedness. In this paper, we report the discovery that chiral differentiation also exists in the diffusion of limonene, which is non-mesogenic in chiral nematic liquid crystals. The diffusion of l-limonene (right-handed) in chiral nematic liquid crystals with a right handed helical structure is faster than that of d-limonene (left-handed). This result might be important in understanding the effects of chirality on physical processes that take place in biological systems. In addition, this effect could be utilized for enantiomer separation in the pharmaceutical industry.