Comparison of Mesomorphic Properties in Chiral and Achiral Homologous Series of High Tilted Ferroelectrics and Antiferroelectrics

Abstract

Homologous series of chiral (S) 4-(1-methylheptyloxycarbonyl)-phenyl and achiral 4-(4-heptyloxycarbonylphenyl 4-(perfluoroalkanoyloxyhexyloxy)biphenylates or 4-(alkanoyloxyhexyloxy)biphenylates, chiral (S) and racemic (R,S) 4′-(1-methyl heptyloxycarbonyl)biphenyl-4-yl 4-(perfluoroalkanoyloxyhexyloxy)benzoates or 4 (alkanoyloxyhexyloxy)benzoates have been prepared and their phase transitions have been investigated by DSC and polarizing thermomicroscopic methods. Moreover the temperature dependence of interlayer spacing by a small angle X-ray diffraction method has been studied. The chiral and achiral members exhibit a SmC _anti. phase, while racemic members only exhibit SmC phase. Fluorinated compounds have lower melting points, lower melting enthalpy and broader range of the SmC _anti. phase than earlier prepared series with shorter spacer group (CH ₂ ) _m , m < 6. They are very useful components for the formulation of orthoconic (interlayer tilt 90°) antiferroelectric mixtures with temperature range from (−20°C) to 100°C.

Keywords:

• Chiral and racemic smectics
• high tilted smectics
• interlayer spacing
• phase transition thermodynamic data
• antiferroelectric orthoconic mixtures

Acknowledgment

Financial support from the Polish Government (K.B.N.) grant No 4T09A 103 24 and European Network “SAMPA.”