Helical twisting behaviour of new chiral dopants with (S)-1, 2-propanediol units for nematic liquid crystals

Abstract

A novel series of chiral dopants synthesised from (S)-1, 2-propanediol and mesogenic carboxylic acids were characterised by Fourier transform infrared and ¹H nuclear magnetic resonance, and their helical twisting properties were investigated by doping the chiral dopants into a nematic liquid crystal host (SLC-1717). The results showed that the values of the molecular twisting power β were significantly dependent on the nature of the terminal substituents, terminal alkyl length and numbers of chiral centres in the molecular structure. Compared to compounds with electron-with-drawing groups (-NO₂, -F, -CF₃), the chiral compounds with terminal alkyl chains exhibited a higher β.

Keywords:

• chiral dopants
• chiral nematic
• pitch
• molecular twisting power
• liquid crystal

Acknowledgements

Financial support is acknowledged from the National Science Foundation under Grant No. 20674005, the Flat-Panel Display Special Project of China 863 Plan under Grant No. 2008AA03A318 and Projects of Chinese National Science and Technology Tackling Key Problems under Grant No. 2007BAE31B02.