Synthesis and physical properties of novel liquid crystals containing 2,3-difluorophenyl and 1,3-dioxane units

Abstract

Three series of liquid crystalline materials have been synthesized: 2-(2,3-difluoro-4-alkoxyphenyl)-5-(4-alkylphenyl)-1,3-dioxanes (m,On-DFPPD), 2-(2,3-Difluoro-4-alkoxyphenyl)-5-(2-fluoro-4-alkylphenyl)-1,3-dioxanes (m,On-DFPFPD) and 2-(2,3-Difluoro-4-alkoxyphenyl)-5-(2,3-difluoro-4-alkylphenyl)-1,3-dioxanes (m,On-DFPDFPD). Their mesmorphic properties were observed and measured by polarizing optical microscopy and differential scanning calorimetry. The dielectric anisotropy (Δε) and birefringences (Δn) of some target compounds were determined. Most of these compounds exhibit a wide temperature range smectic A phase and/or a wide temperature range nematic phase with negative dielectric anisotropy (Δε) and low birefringences (Δn).