Effect of fluorination of molecular rigid core in liquid crystal biphenyl benzoate based homologous series

Abstract

Liquid crystalline perfluorinated biphenyl benzoates were synthesized and investigated. A highly tilted, neat orthoconic smectic antiferroelectric phase was observed. A homologous series of compounds without and with a single fluorine atom substituted at different positions of a molecular rigid core was investigated by standard methods. Influence of fluorine substitution on physical properties of antiferroelectric smectic phase was discussed as well as influence of fluorination on molecular dipole moment orientation and its value were presented. Decrease in rotational viscosity as a result of fluorine substitution within a molecular rigid core was ascribed to changes of molecular packing.

Modification of electro-optical properties of an orthoconic chiral biphenyl smectogen with its isostructural carborane analogue

“…3 New possibilities in solving these problems appeared with the development of surface-stabilized orthoconic antiferroelectric liquid crystals (SSOAFLC), which typically contain a partially fluorinated alkyl substituent. [4][5][6][7][8] Molecules in this rare class of mesogens adopt 45 tilt angle q in a single layer and 90 alternating tilt angle from one smectic layer to another. 9 Consequently, in the surface stabilized geometry and zero external electric field, the OAFLCs form a medium which is optically uniaxial and optically negative with the optical axis perpendicular to the OAFLC slab.…”

Dielectric relaxation spectroscopy and electro-optical studies of a new, partially fluorinated orthoconic antiferroelectric liquid crystal material exhibiting V-shaped switching

“…The investigated sample belongs to a new series of partially fluorinated OAFLC synthesised by Morawiak et al [27]. The molecular structure is shown in Figure 1 and its phase sequence is Cr<57:5 C SmC A Ã 83:9 C SmC Ã 110:8 C SmA 114:9 C Iso…”

Design, synthesis and mesomorphic properties of chiral benzoates and fluorobenzoates with direct SmCA*-Iso phase transition

“…[14] Recently, the high tilted antiferroelectric phase was found in compounds with a partially fluorinated alkoxyalkoxy chain. [15] They are more chemically stable and have a longer helical pitch than those compounds with an alkanoyloxyalkoxy group, later also compounds and mixtures with long pitch were found. Uniaxial properties are observed only when the tilt differs from the orthoconic angle by no more than three degrees.…”