Kanetsugu Terashima

Chiral smectic C liquid crystals having an electronegative substituent ortho to the chiral tail group - a study of a factor determining the magnitude of spontaneous polarization

Abstract Chiral smectic C compounds having an ester group in the central core, an optically active tail group (alkoxy or alkoxycarbonyl), and an electronegative substituent (halogen or cyano) ortho to the chiral tail were synthesized. The effect of the ortho substitution on the characteristics, especially on spontaneous polarization (Ps), was examined. When the chiral tail is a 1-methylheptyloxy group the lateral substituent increases Ps relative to the unsubstituted analogue. In the case of 1-methylheptyloxycarbonyl tail group, however, the lateral substituent decreases Ps relative to the unsubstituted. These effects of lateral substituents are explained in terms of chemical structure of a single molecule, i. e., by taking statistical weight of conformers and the associated electric dipole moments into account.

Physical Properties of Some Chiral Smectic Liquid Crystals Having 1-Methyl-Alkoxy-Phenyl Group

Abstract The liquid crystalline compounds having an optically active 1-methyl-alkoxy-phenyl group were synthesized. They show some abnormality, i.e., firstly rather high value of spontaneous polarization for the structural feature lacking a strongly polar group, in the vicinity of the chiral center, and secondly the sense of twist in the S*c phase that is opposite to what was originally expected. We report the characteristics of these compounds.

Some Observations on the Sense and Magnitude of Spontaneous Polarization and Twisting Power of a Number of Ferroelectric Liquid Crystal Types

Abstract The sense and magnitude of spontaneous polarization of a number of ferroelectric liquid crystal types were measured. Compounds with a polar group close to the chiral center showed large Ps values, amounting to 150 nC/cm2 in the highest case. The alteration of signs of Ps as the chiral center is moved stepwise from the central core in the series of compounds having an alkyl or alkoxy wing chain was examined. Compounds in which the chiral center is connected to the core by an ether linkage showed singularity. The well-known SED-ROD and SOL-REL rule for cholesterics applied to almost all the diverse types of compounds of the present study also in the S*c phase.

2, 3-Dicyanohydroquinone Derivative Liquid Crystals Having Strong Negative Dielectric Anistropy

Abstract Three groups of liquid crystalline derivatives of 2,3-dicyanohydroquinone were synthesized. The dielectric anisotropy values, δes, for these compounds were estimated to be around −20 by extrapolation. Some basic evaluations of these compounds, in view of their application as component materials for the practically usable nematic mixtures of highly negative δe, were made using their solution in a substituted phenyl cyclohexanecarboxylate nematic mixture; δ e. viscosity, dichroic ratio of dyes, driving voltages, and response times, are described in relation to their molecular length. By use of several selected members of these compounds in summe of about 20 wt% in low viscosity base nematics, one can make practical nematic compositions having δe of −5 and viscosity of 40 cp at 20°. The guest-host display device can be driven with 3 volts at acceptable response times of 100-200 milliseconds at room temperatures, to give positive color contrast, i. e. colored in on-state.

Synthesis and Some Properties of Low Melting Ferroelectric Liquid Crystals of Benzylidene Anilines

Abstract A series of chiral benzylidene-aniline compounds, 4-alkoxybenzylidene 4′-(2-methylbutyloxycarbonyl)anilines, have been synthesized and their mesomorphic properties are examined. They showed a monotropic chiral smectic C phase in conjunction with enantiotropic smectic A phase, and their chiral smectic C—smectic A phase transition temperatures are around room temperatures. Their spontaneous polarization values are moderately higher than those of DOBAMBC “4-decyloxybenzylidene 4′-amino-(2-methylbutyl)cinnamate”.

Liquid Crystalline Compounds Having 1,2,3-Trifluorophenyl Substituent for AM-LCDs with Low-Voltage IC Driver

Abstract Two- or three-ring compounds having 1,2,3-trifluorophenyl substituent (3F-compounds) were synthesized and their physical properties were measured to evaluate the applications to active matrix liquid crystal displays(AM-LCDs). The 3F-compounds gave good physical properties for AM-LCDs and, in particular, an excellent voltage-holding ratio (VHR), comparable to the compounds having 1,2-difluorophenyl substituents (2F-compound) which are currently used for AM-LCDs. The important point is that 3F-compounds showed much lower threshold voltage (V 10) than 2F-compounds. It was demonstrated that one mixture of 3F-compounds with 2F-compounds gave V 10 of about 1.30V at 5.5μm-cell gap. From these results, it was concluded that the 3F-compounds are excellent liquid crystalline materials for AM-LCDs with a low-voltage IC driver, for example the 3V IC driver.

Studies of Intermolecular Interaction in Binary Nematic Mixtures of p-Methoxybenzylidene—p′-n-Butylaniline and p-Cyano-p′-n-Pentylbiphenyl by Dielectric Relaxations

Abstract Anisotropic dielectric relaxations at the nematic state under magnetic field and viscosities at the isotropic state were measured in MBBA-CPB systems with various mole% of CPB. The intermolecular interaction in the systems with different mole% of CPB was estimated by the MaierSaupe theory from the dielectric relaxations and the viscosities. A long range-intermolecular interaction increased anomalously near the two CPB concentrations exhibiting the eutectic points (15 and 75 mole% of CPB). This was explained by some component fluctuation originating in the inversion of solvent-solute relationships at the eutectic mixing ratio.

Novel optically active compounds having 2-alkanoyloxypropyl moiety as chiral dopants

Abstract Novel optically active compounds having 2-alkanoyloxypropyl moiety were synthesized. By use of these compounds as chiral dopants in an achiral smectic C mixtures, Sc* mixtures exhibiting quick response and a long N* pitch suitable for the SSFLC displays could be obtained.