Magnetic fields have been used to flip the chirality of liquid crystals
Wolfgang Weissflog and his colleagues at the Martin Luther University and Leipzig University in Germany prepared five bent rigid liquid crystal components, or mesogens, and found that by varying the chain length of individual molecules these banana-shaped liquid crystals formed different layered phases.
In one phase, known as the polar smectic phase, the molecule’s arrangement makes the material chiral even though the individual molecules in the material are not chiral.
By investigating this phase of their material Weissflog’s team could invert the chirality by applying an external electric field. Also, this switching mechanism changed as the temperature increased.
Weissflog and his collaborators are now investigating this interesting phenomenon further. ’Above all we would like to understand the molecular background of the existence of the competing switching mechanisms,’ comments Weissflog, ’another interesting and more general question is the influence of conformational changes on the formation of polar mesophases.’