New ylidene and spirocyclopropyl derivatives of cholestanone and dehydroepiandrosterone series and their ability to induce cholesteric mesophase in nematic solvent

ABSTRACT

New ylidene and spirocyclopropyl derivatives of cholestanone and dehydroepiandrosterone series were synthesized and their structure was determined by X-ray analysis. These compounds may be used as chiral dopants for cholesteric liquid crystal compositions which are applied in bistable displays with low power consumption. The ability of the synthesized substances to induce cholesteric mesophase in 4′-pentyl-1,1′-biphenyl-4-carbоnitrile nematic solvent was examined. The highest values of the helical twisting power |β| (190.0 ± 2.3) and (165.5 ± 1.9) µm⁻¹ mol pats⁻¹ were showed by (E)-2-{[3-(1,1′-biphenyl-4-yl)-1-phenyl-1H-pyrazol-4-yl]methyldene}-cholestanon and (1S,2S)-1-(1-phenyl-3-(4-methoxyphenyl)-1H-pyrazole-4-yl)-2,16′-spirocyclopropyldehydroepiandrosterone, correspondingly.

GRAPHICAL ABSTRACT

KEYWORDS:

• Chiral dopants for cholesteric liquid crystal compositions
• helical twisting power
• spirocyclopropyl derivatives of cholestanone and dehydroepiandrosterone
• X-ray analysis