摘要:
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.
摘要:
Liquid-crystalline phenylpyrimidinyl cyclohexanecarboxylates having a smectic phase, a process for their preparation, and their use in liquid-crystal mixtures The phenylpyrimidinyl trans-cyclohexanecarboxylates of the general formula ##STR1## form a smectic C phase besides a relatively broad nematic phase when R.sup.1 denotes an alkyl radical having 10 to 16 carbon atoms, in particular 11 to 16 carbon atoms, or an alkoxy radical having 8 to 14 carbon atoms, and R.sup.2 denotes an alkyl radical having 2 to 9 carbon atoms. They are therefore particularly suitable as components of liquid-crystalline mixtures having a smectic C phase since they induce a relatively broad nematic phase or extend a narrow nematic phase which is present and extend the temperature range of the smectic C phase to low temperatures, but in particular to high temperatures.
摘要:
The novel compounds are aryl-2,3-epoxyalkyl ethers or thioethers or the corresponding thiirane compounds having a mesogenic aromatic component and a chiral component having a three-membered heterocyclic ring, wherein, in the general formula (1), ##STR1## the symbols have the following meaning: R.sup.1 =straight-chain or branched (C.sub.1 -C.sub.12) alkyl, where one or two non-neighboring CH.sub.2 groups may be replaced by O or S atoms.A=diazine-2,5-diyl or diazine-3,6-diyl,X and Y=O and/or S, andR.sup.2, R.sup.3 and R.sup.4, independently of one another=H, straight-chain (C.sub.1 -C.sub.10) alkyl or branched (C.sub.3 -C.sub.10) alkyl, where R.sup.2, R.sup.3 and R.sup.4 are not simultaneously H.The compounds are preferably employed in tilted smectic liquid-crystal phases which they convert into ferroelectric liquid-crystal phases; they have high values for spontaneous polarization or they induce high values for spontaneous polarization.
摘要:
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.
摘要:
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.1, --M.sup.2 =bridges such as --CO--O, --OCH.sub.2 or --CH.dbd.CH; X=oxygen or sulfur.
摘要:
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.The particular advantage of the compound of the general formula (I) is that it can induce a high twisting capacity in a cholesteric phase.
摘要:
Optically active oxirane-2-carboxylic acid esters with a mesogenic molecular component suitable as dopants in liquid-crystal mixtures. They result in liquid-crystalline ferroelectric phases with short switching times and in electroclinic phases with large electroclinic coefficients. A further advantage lies in the fact that they induce a helix with a very small pitch so that they are also suitable for helix compensation in LC mixtures.
摘要:
Optically active 1,3-dioxolane derivatives which carry a mesogenic radical in the 4-position and have the general formula (I) ##STR1## are suitable for use as doping agents in liquid-crystal mixtures--in particular ferroelectric liquid-crystal mixtures. The symbols in the general formula have the following meanings:R.sup.1 is composed analogously to the part of the general formula on the right-hand side of X or is an alkyl or alkylene radical which can be substituted,R.sup.2, R.sub.3 and R.sup.4 are H or alkyl (R.sup.4 is also alkenyl) which can also be substituted [R.sup.2 and R.sup.3, together with the C(2) of the dioxolane ring are also a cycloaliphatic radical or a keto group], J, l and n are zero, 1 or 2 and k and m are zero or 1, subject to the proviso that, if k is zero n is zero and if n is zero m is zero and 1.ltoreq.J+l+n.ltoreq.3,--A.sup.1, --A.sup.2 and --A.sup.3 are an aromatic, heterocyclic or aliphatic ring system, --M.sup.1 and --M.sup.2 are --CO--O, --0--CO, --CH.sub.2 CH.sub.2, --CH.dbd.CH, --CH.sub.2 O, --OCH.sub.2 or --C.tbd.C andX is O, S or O--CO--O.
摘要:
Optically active, mesogenic 1,3-dioxolane-4-carboxylates are suitable as dopes in liquid-crystal mixtures. They result in liquid-crystalline ferroelectric phases having short switching times and in electroclinic phases having large electroclinic coefficients. Their particular advantage is that they induce a helix of very large pitch, meaning that helix compensation by further dopes is unnecessary. In addition, the 1,3-dioxolane-4-carboxylates exhibit high UV stability.
摘要:
The novel liquid-crystalline mixtures (in the case of ferroelectric behavior they additionally contain an optically active compound as dope) are constructed from at least 2 mixture components of the general formula (I): ##STR1## wherein n=6 to 14 and x=2 to 14. In addition, the mixtures may also contain cyclohexanecarboxylates of the general formula (II) ##STR2## where R.sup.1 =(C.sub.10 -C.sub.16) or (C.sub.8 -C.sub.14)alkoxy and R.sup.2 =(C.sub.2 -C.sub.9)alkyl, alkenyloxyphenylpyrimidine derivatives of the general formula (III) ##STR3## where R.sup.3 =(C.sub.7 -C.sub.16)alkyl or (C.sub.6 -C.sub.14)alkoxy and y=4-14, and/or alkoxyphenyl derivatives of alkylpyrimidine, of the general formula (IV) ##STR4## where m and p=6 to 14.