New chiral LC acrylates: Polar ordering in crystal and smectic phases

Abstract

Two mesogenic acrylates derived from (R)-5-bromo-4-methylpenta-noic acid, having biphenyl moiety, have been synthesised and characterised by POM, DSC, X-ray, pyro- and piezoelectric techniques. The only real difference in molecular structure of the compounds is that the one contains terminal octyloxy group (1) and the other has octanoyloxy group (2). Crystal structures of the acrylates were shown to be precursors of tilted smectic phases. Both compounds are manomorphic exhibiting either smectic I* phase (1) or smectic crystal H* phase (2). 1 crystallises in non-polar space group while the crystallisation of 2 yields crystals with a polar axis. Good correlations were found in electric responses between the crystalline phases and mesophases of both the acrylates.

Keywords:

• smectic I*
• crystal smectic H*
• X-ray
• pyroelectric and piezoelectric measurements