Controlling chirality with helix inversion in cholesteric liquid crystals

Abstract

The helical organization of cholesteric liquid crystals is omnipresent in living matter. Achieving control over the structure of the cholesteric helix consequently holds great potential for developing stimuli-responsive materials matching the level of sophistication of biological systems. In particular, inversion of a cholesteric helix is associated with inversion of the circular polarization of the light it reflects. While control over the cholesteric period has been thoroughly investigated, reports on helix inversion are scarcer. Predicting which systems display helix inversion also remains a challenge because of the subtle balance of contributions underlying this phenomenon. Here we provide an overview on recent advances in controlling and understanding helix inversion in cholesteric liquid crystals

Photoresponsive Cholesteric Liquid Crystals

“…Temperature-dependent helix inversion can be achieved based on either molecular conformation change or the equilibrium shift between opposite chiralities of multiple chiral centers [61]. However, these systems are not favorable for practical applications due to the high processing temperature.…”

Propagation of Chirality in Mixtures of Natural and Enantiomeric DNA Oligomers

“…A notable exception is the lack of a general theory for the prediction of how strongly the presence of chiral centers in molecules affects phase behavior and structure on mesoscopic length scales [1]. Even when the molecular shape is symmetric and very well known, such as the double helical shape of B-DNA, the cooperative effects of the molecular chirality are amazingly complex and hard to model [2][3][4][5]. The recent discovery of the liquid crystal chiral nematic (N * ) phase in solutions of ultra-short DNA double helices (down to 6 bases) [6] has offered new opportunities to explore this topic.…”

Chiral Liquid Crystals: Structures, Phases, Effects

“…Only, if one enantiomer forms a cholesteric that reflects a certain handedness, its mirror image will reflect the other circular polarization. First attempts to predict the helical handedness through knowledge of the molecular configuration are being made via combining experiments with theory and computer modeling, for example by the Ferrarini group ( [41], and references therein). The optical effect of selective reflection occurs without the 180° phase shift originally observed for reflection off mirrors.…”