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AbstractNew synthetic schemes for the preparation of liquid crystalline compounds which provide for the use of substituted 1-cyclopropanoles as the key intermediates are reported. Two main directions for the transformation of cyclopropanoles into LC compounds have been applied: a) the using of cyclopropanoles as the precursor of vinyl ketones in the “condensation building” of cyclohexenone ring which can be then converted into both laterally substituted and unsubstituted cyclohexyl or cyclohexenyl moiety; b) the opening of cyclopropane ring which allow to construct the functionally substituted terminal side chain.

The new pathway for the synthesis of optically active LC derivatives of biphenyl, terphenyl and quaterphenyl especially lateral substituted ones has been worked out. 3-Aryl-6-alkylcy-clohex-2-en-l -ones arriving from the Michael type condensation of Mannich salts with the corresponding 2-alkylacetoacetic esters were used as the key starting compounds. The phase transition temperatures and properties for the prepared new LC compounds are discussed.

AbstractWe have proposed and realised a new synthetic approach for the preparation of liquid crystalline dicyclohexyl derivatives. Recently discovered reaction of Grignard reagents with esters leading to 1-substituted cyclopropanoles in the presence of tetraisopropoxytitanium was used as a key stage. Starting from ethyl trans-4-alkylcyclohexancarboxylates the corresponding 6-(4-alkylcyclohexyl)-3-alkylcyclohex-2-en-1-ones have been prepared. Their catalytic hydrogenation in the base media gave mainly saturated trans,trans-ketones which are liquid crystalline and can be used also as a promising intermediate products for the preparation of different kinds of other LC compounds containing bicyclohexane moiety.

AbstractA set of new, blended nematic liquid crystal mixtures to improve the performance of highly multiplexed TN-displays are presented. The physical and electro-optical properties of new LC mixtures have been investigated, along with the frequency and temperature dependence of threshold voltage about newly developed liquid crystals. The multiplexable mixtures are completely miscible and can be blended, thus leading to new mixtures covering a wide range of threshold voltages 1.2 > V10> 2.0 V, nematic-isotropic phase transition temperatures 60 > Tc > 100[ddot]C, and/or optical anisotropies 0.13>Δ n>0.18.

The new pathway for the synthesis of lateral chloro substituted biphenyl carboxylic acids and phenols has been worked out. 3-Aryl-6-alkylcyclohex-2-en-1-ones arriving from the Michael type condensation of Mannich salts with the corresponding 2-alkylacetoacetic esters were used as the key starting compounds. The prepared carboxylic acids and phenol were applied as semiproducts for the synthesis of variety of the optically active esters. The phase transition temperatures for the prepared compounds are determined.

The influence of chemical modification destroying liquid-crystalline properties on dipole relaxation of a polar nematogen is investigated.

AbstractA new improved approach to prepare the liquid crystalline bicyclohexylbenzene derivatives is proposed. The key stage is the synthesis of 3-(trans-4-arylcyclohexyl)-6-alkyl (or aryl) cyclohex-2-en-1-ones via the condensation of the corresponding Mannich salts with 2-substituted acetoacetic esters (or methyl benzyl ketones) in the presence of a base. The catalytic hydrogenation of these cyclohexenones in base media gives mainly saturated trans-ketones which are promising semiproducts for the preparation of different kinds of the LC compounds containing a bicyclohexyl fragment. The chemical transformations of the prepared cyclohexanones were carried out and as a result a range of LC compounds both known and new ones were synthesized.

AbstractThe synthesis and mesomorphic properties of several dozen 3,6-disubstituted cyclohex-2-enones are described. The compounds were obtained by the condensation of 4-substituted β-(N,N-dimethylamino)ethylphenyl ketone hydrochlorides (Mannich salts) with 2-alkylacetoacetic esters. The influence of the structure of the reactants, catalysts and solvents on the yield is discussed.

AbstractThis paper presents a number of laterally substituted liquid crystalline compounds which have been synthesized by systematically varying both the position and the type of the lateral substituent.

We demonstrate a quarter wave phase retarder consisting of two layers of different liquid crystals (LCs). The phase retardation does not differ by more than ±5% from the target value π/2 within a spectral interval of 200 nm in the visible range. These values are comparable to the data for commercial two layer crystalline retarders which are much more expensive, especially if large apertures are required. In order to design the LC retarder we measured the birefringence of the LC within the entire visible spectrum using a published technique which does not consider interference effects due to reflections within indium-tin oxide coated LC cells. We show that these effects do not affect the results adversely provided that the birefringence data are taken over a broad spectral range.

The type of bonds responsible for the complexation of di- and polyacids with the tertiary amine β-N-dimethylamino-4-dodecyloxypropiophenone is studied by means of FTIR spectroscopy. The complexes are shown to be stable due to strong H-bonding with partial charge transfer. The characteristic composition for complexes of polyacrylic, polymethacrylic and malonic acids is calculated as 2:1 (number of carboxylic groups per number of amine molecules) whereas glutaric acid forms complexes of different composition including 1:1. The characteristic composition results from the structure of the initial acid. The structures of both the characteristic complex and “excess” acid are also discussed.