Abstract: Ferroelectric liquid crystal mixtures containing compounds of the formula (I): ##STR1## wherein R.sup.1 is, for example, a straight-chain or branched alkyl radical having 1 to 22 carbon atoms, in which one --CH.sub.2 -- group may be replaced by --O-- or --CO--O--.

Abstract: A process for the stabilization of the spatial alignment of the smectic layers in an FLC switching and/or display element, in which the original position of the smectic layers has been modified by electrical field treatment, which comprises alternately switching the elements during non-operation and/or when a certain temperature is exceeded which is above a predetermined temperature range which includes the operating temperature region and/or when the temperature falls below a certain temperature which is below a predetermined temperature range which includes the operating temperature region. Use of the process according to the invention ensures long-term functioning of the switching and display device, even in the case of repeated regeneration of the quasi-bookshelf geometry, and prevents worsening in the contrast and brightness and the occurrence of ghost images.

Abstract: A ferroelectric liquid crystal mixture which does not lower the conventional transition temperature to the ferroelectric phase (60.degree. C. or above), which maintains the Sa phase within a suitable temperature range, and which is useful for reducing the cone angle is disclosed. The ferroelectric liquid crystal mixture contains at least one of the compounds represented by the following general formulae 1 to 3, and exhibits a Sa/Sc phase transition temperature of 60.degree. C. or more and a cone angle of 47 degree or less atsome temperature between 15.degree. C. and 35.degree. C.

Abstract: A ferroelectric liquid crystal mixture containing two or more components, at least one of which is a complex ligand for ions, in particular for cations, is particularly suitable for use in ferroelectric liquid crystal displays.

Abstract: A ferroelectric liquid crystal mixture which does not lower the conventional transition temperature to the ferroelectric phase (60.degree. C. or above), which maintains the Sa phase within a suitable temperature range, and which is useful for reducing the cone angle is disclosed. The ferroelectric liquid crystal mixture contains at least one of the compounds represented by the following general formula 1 to 3, and exhibits a Sa/Sc phase transition temperature of 60.degree. C. or more and a cone angle of 47 degree or less atsome temperature between 15.degree. C. and 35.degree. C.

Abstract: Compounds of formula I ##STR1## in which R.sup.1 and R.sup.2 are, for example, an alkyl chain,A is a mesogenic group, andM is a spacer group,are highly suitable as components of liquid-crystal mixtures.

Abstract: Ferroelectric liquid-crystal systems having high spontaneous polarization, in particular >35 nC cm.sup.-2, and good orientation properties in the ferroelectric phase, in particular the S.sub.C * phase, contain at least three different optically active compounds, preferably as dopes in a base mixture which is not itself optically active and has a nematic phase above the smectic phase. The optically active compounds are selected so that they do not all induce a helix of the same rotation sense in the nematic phase. Their relative concentrations are selected so that the total resultant pitch of the helix throughout the cholesteric phase is not less than 10 .mu.m.

Abstract: A pyridylpyrimidine compound of the formula (I) ##STR1## in which A is N and B is CH or A is CH and B is NC is N and D is CH or C is CH and D is N,R.sup.1 is, for example, chiral or achiral alkyl having 1 to 16 carbon atoms,R.sup.2 is, for example, , R.sup.1,X.sup.1, X.sup.2 are F, Cl or CN, andn, m are 0, 1 or 2,are components which are suitable for liquid-crystalline mixtures since they result in LC displays having favorable properties.

Abstract: A process for producing a liquid-crystal cell by using a ferroelectric liquid crystal (FLC) composition containing at least one oleophilic substance that exhibits liquid crystallinity and at least one additive having lower boiling point than said substance, characterized in that said FLC composition is charged into the cell under high-temperature and high-vacuum conditions, provided that the two conditions will not overlap, or will overlap for a sufficiently short time to effectively prevent the evaporation of said additive.

Abstract: Disclosed and claimed are liquid-crystalline cyclopropylalkyl or -alkenyl or heterocyclic compounds, process for their preparation, and their use in liquid-crystalline mixtures. The novel cyclopropylalkyl or -alkenyl or heterocyclic compounds are of the general formula ##STR1## In this formula A.sup.1, A.sup.2 and A.sup.3 are unsubstituted or substituted, aromatic or heteroaromatic molecular components such as 1,4-phenylene or pyrimidine-2,5-diyl which are linked via a single bond (in the case where k and m=0) or via functional groups M.sup.1 and M.sup.2, such as CO--O or CH.sub.2 --O; j, k, l, m and n are zero, 1 or 2. The radicals R.sup.2, R.sup.3 and R.sup.4 are H or alkyl/alkenyl, R.sup.1 is alkyl/alkenyl or one of the substitutents known from LC chemistry such as an .alpha.-haloalkanoic acid radical. At least one of the components A.sup.1, A.sup.2 and A.sup.3 can be heteroaromatic, and G is alkylene or alkenylene.

Abstract: The use of optically active tetrahydrofuran-2-carboxylic acid esters as dopants in liquid-crystal mixtures, liquid-crystal mixtures containing same and novel optically active tetrahydrofuran-2-carboxylic acid esters.Optically active tetrahydrofuran-2-carboxylic acid esters containing a mesogenic molecular building unit are suitable as dopants in liquid-crystal mixtures. They result in liquid-crystalline ferroelectric phases having short switching times and in electroclinic phases having large electroclinic coefficients. A further advantage is that they induce a helix having a very small pitch so that they are also suitable for helix compensation in LC mixtures.The compounds are symbolized by the general formula: ##STR1## in which the symbols and indices essentially denote: R.sup.1 =alkyl/alkenyl or tetrahydrofurancarbonyloxy or -thio; j, l, n=zero, 1 or 2; k, m=zero or 1; --A.sup.1, --A.sup.2, --A.sup.3 =phenylene, cycloalkylene or corresponding heterocyclates containing nitrogen, oxygen or sulfur; --M.sup.

Abstract: The novel ferroelectric liquid-crystalline mixtures are based on at least two mixture components of the general formula (I) ##STR1## but additionally contain at least one optically active dope from one or more of the following groupsa) optically active esters of tetrahydrofuran-2-carboxylic acidb) optically active aryl 2,3-epoxyalkyl ethersc) optically active 1,3-dioxolan-4-yl ethers.The ferroelectric LC mixtures have a high spontaneous polarization and facilitate substantial compensation of the pitch of the helix in a nematic phase.

Abstract: A liquid-crystalline bispyrimidinylcyclohexane of the formula (I) ##STR1## in which: R.sup.1 and R.sup.2 are identical or different and are, for example, straight-chain or branched alkyl,X.sup.1 and X.sup.2 are identical or different and are H, F, Cl or CN,is particularly suitable as a component of liquid-crystal mixtures.In nematic and smectic liquid-crystal mixtures, these compounds result in low melting points and broad phase ranges.

Abstract: Geminal dimethylalkyl compounds, process for their preparation and their use in liquid-crystalline mixtures Geminal dimethylalkyl compounds of the formula (I) ##STR1## in which: R.sup.1 is, for example, straight-chain or branched (with or without an asymmetric carbon atom) alkyl or alkenyl having 2 to 16 carbon atoms,A.sup.1, A.sup.2 and A.sup.3 are, for example, identical or different 1,4-phenylene, 1,4-cyclohexylene or pyrimidine-2,5-diyl,M.sup.1 and M.sup.2 are, for example, identical or different CO--O or O--CO,G is for example, identical or different straight-chain or branched alkylene having 1 to 16 carbon atoms,k, l, m and n are zero or 1, andR.sup.6 is straight-cain alkyl having 1 to 10 carbon atoms,can advantageously be employed in liquid-crystalline mixtures. In liquid-crystalline mixtures, said compounds result in a melting point depression, in a shift in the temperature limit of the S.sub.c phase in ferroelectric mixtures and in other improvements of important electrooptical characteristic values.

Abstract: A process for producing a liquid-crystal cell which comprises the steps of:(a) providing a curable sealant portion in the periphey of the side of an electrode plate that has an electrode or electrodes;(b) (i) coating a ferroelectric liquid-crystal composition on the portion surrounded by said sealant portion, with a spacer being preliminarily provided in said portion;(ii) coating spacer-containing ferroelectric liquid-crystal composition on the portion surrounded by said sealant portion; or(iii) coating a ferroelectric liquid-crystal composition on the portion surrounded by said sealant portion and thereafter providing a spacer over said composition;(c) defoaming the coated layer of the liquid-crystal composition by heating during or after evacuation;(d) placing the other electrode plate in such a way that the side of said other electrode plate which has an electrode or electrodes faces the side of said one electrode plate containing the thermally defoamed coated layer of the liquid-crystal composition and co

Abstract: Use of optically active carboxylic esters of oxygen-containing heterocycles as doping substances in liquid crystal mixtures and liquid crystal mixtures containing them.Optically active 1,3-dioxolane-4-carboxylic esters and oxirane-2-carboxylic esters of the general formula (I)R(--A.sup.1).sub.j (--M.sup.1).sub.k (--A.sup.2).sub.l (--M.sup.2).sub.m (--A.sup.3).sub.n --X--Acin whichR.sup.1 is, for example, (C.sub.1 -C.sub.16)-alkyl or (C.sub.1 -C.sub.16)-alkoxy,A.sup.1, A.sup.2, A.sup.3 are, for example, phenyl or pyrimidine-2, 5-diyl,M.sup.1, M.sup.2 are, for example, CO--O, CH.sub.2 --CH.sub.2,j, l are 0, 1, 2,k, m are 0, 1,n is 0, 1, 2,X is O, S andAc is ##STR1## in which R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6 for example, H or methyl, are particularly suitable doping substances for liquid crystalline mixtures, since they induce a high spontaneous polarization and effect a substantial decrease in the melting point.

Abstract: A method of driving a ferroelectric liquid crystal element which enlarges the effective cone angle. A ferroelectric liquid crystal is held between two substrates such that the helix is suppressed and a chevron layer structure is present. The ferroelectric material has a positive dielectric anisotropy. A first pulse is applied which causes switching from one state to the other, and a subsequent smaller AC pulse is applied which does not cause switching. The second pulse voltage control the effective cone angle, enabling grey scale.

Abstract: The novel silylalkyl or silylalkenyl compounds correspond to the general formula (I) ##STR1## Here the symbols A.sup.1, A.sup.2, A.sup.3 denote aromatic or heteroaromatic molecular units such as 1,4-phenylene or pyrimidine-2,5-diyl which are combined via a single bond (for k, m=0) or via functional groups M.sup.1,M.sup.2 such as CO--O or CH.sub.2 --O; j, k, l, m, n are zero or 1 (j+l+n=2 or 3). The radicals R.sup.2, R.sup.3, R.sup.4, R.sup.5 are hydrogen or alkyl/alkenyl, cycloalkyl, and the radicals R.sup.6, R.sup.7, R.sup.8 have a comparable meaning (hydrogen); R.sup.1 is alkyl/alkenyl or one of the substituents known from LC chemistry such as an .alpha.-haloalkanoic radical. In some cases compounds have wide and polymorphous liquid crystalline phases.

Abstract: The use of a fluoropyrimidine derivative of the general formula (I) as component in a ferroelectric liquid crystal mixture comprising 2 to 20 components, ##STR1## in which the symbols have the following meaning: R.sup.1 and R.sup.2 independently of one another are, for example, straight-chain or branched alkyl having 1 to 16 carbon atoms,a and b are, for example, both equal to 0 or 1, ##STR2## for example, phenylene or cyclohexylene, and --M.sup.1 -- is, for example, --CO--O--, --O--CO--, --CH.sub.2 --O-- or --O--CH.sub.2, leads to improved switching characteristics in electrooptical display devices.

Abstract: Optically active 1,3-dioxolane derivatives of the general formula (I) ##STR1## are suitable as doping substances in liquid crystal mixtures. The symbols in the general formula have the following meaning:R.sup.1 has the structure which is analogous to the moiety of the general formula which is on the right of X or is an alkyl or alkylene radical which can be substituted, R.sup.2, R.sup.3 are H or alkyl, which can also be substituted [R.sup.2, R.sup.3 can also be a cycloaliphatic compound together with C(2) of the dioxolane ring],R.sup.4 is vinyl or ethyl, with the proviso that at least one radical R.sup.4 is vinyl or ethyl, if R.sup.1 is analogous to the moiety of the formula (I) which is on the right of X, --A.sup.1, --A.sup.2, --A.sup.3 are an aromatic, heterocyclic or aliphatic ring system,--M.sup.1, --M.sup.2 are --CO--O, --O--CO, --CH.sub.2 CH.sub.2, --CH.dbd.CH, --CH.sub.2 O, --OCH.sub.2, --C.dbd.C andX is O, S or O--CO--O.