Nina Chernova

Structure of optically active compounds and ferroelectric properties of liquid crystals

Abstract A new series of optically active dipole dopants - diesters of 4,4″-terphenyl dicarboxylic acid - have been prepared. Most of the components are high melting substances. Some of 2-chlorine substituted compounds show a chiral smectic C* phase. The Ps value induced by optically active dipole dopants depends on several factors such as the magnitude of the dipole moment and the length of the alkyl tail at the C*-atom, the degree to which rotations of the molecule and the chiral center are hindered. In some cases the experimental PS value of the FLC-mixture induced by a pair of dopants with same Ps sign and opposite helix handedness is higher than the sum of the PS values induced by each dopant independently.

Synthesis and ferroelectric properties of some chiral dopants with a terphenyl central core

Abstract A new series of optically active dopants have been prepared using 4,4”-terphenyldicarboxylic acid and 2-alkanols. These are nonmesomorphic, chemically stable—especially with regard to racemization and UV-light-compounds. Introduction of such a compound into a smectic C matrix of phenylpyrimidine or phenylbenzoate type leads to broadening the smectic C range of the matrix despite the fact that the dopant itself is a nonmesomorphic compound. The Ps value induced by the dopant depends greatly on the length of the alkyl tail attached to the chiral center from the external part of the molecule.

Phase diagrams of liquid crystalline systems with a smectic C phase

Abstract Phase diagrams of binary systems conteining liquid crystalline components with a smectic C phase have been investigated. It has been shown that thermostability of the smectic C phase of the mixtures mainly depends on correlations both of molecular length and tilt angles of components.

Synthesis and ferroelectric properties of some terphenyl derivatives with two terminal substituents of different structures

A new series of terphenyl derivatives with two terminal chiral substituents of different structures have been synthesized. Attachment of a chloro group to the chiral centre promotes the chiral smectic C * mesomorphism. The induced p o and P s values are correlated to the structural features of each chiral tail

Synthesis and ferroelectric properties of terphenyl derivatives with various structures of chiral terminal substituents

Abstract A new series of optically active substances, chiral esters of 4″-n-octylterphenyl carboxylic acid has been prepared. Some of the compounds with chlorine-and cyano-substituent at the chiral center show a smectic C phase. The induced Ps value depends on the dipole moment magnitude and alkyl length chain of the substituent adjacent to the C atom.

Synthesis and physical properties of novel terphenyl type ferroelectric liquid crystals

Abstract A new series of optically active compounds have been prepared using 4,4″-terphenyldicarboxylic acid and S-2-alcoxypropanols-1. These are Sm*C, SmA and N* chemically stable - especially with regard to racemization and UV-light compounds with a small PS value, high twisting power and left handedness of helix.

Specific features op dipole ordering in ferroelectric liquid crystal mixtures

Abstract It has been experimentally demonstrated that dependence of spontaneous polarization of a ferroelectric liquid crystal on the tilt angle can be essentially nonlinear. Concentration dependences of the degree of dipole ordering have been measured for binary mixtures of chiral and achiral cmectic C compounds. The type of these relationships has been shown to be determined by the component molecular structures.