摘要:
The compounds of the general formula (I) ##STR1## are particularly highly suitable as components of smectic, liquid-crystal mixtures, the symbols having the following meaning: R.sup.1 and R.sup.2 denote identical or different, straight-chain or branched alkyl or alkenyl groups which can contain asymmetric carbon atoms, containing 2 to 16 carbon atoms, in which one or more non-adjacent --CH.sub.2 -- groups can be replaced by --O-- and/or --S--, --A and --B each denote group ##STR2## in which the radicals R.sup.1, R.sup.2, in each case, are situated at the phenylene part of --A, --B and m and n denote 0 or 1, but m+n is always zero or 1.
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.
摘要:
Liquid-crystal 5-phenylpyrmidine derivatives having S.sub.c or S.sup.*.sub.c phases and a process for preparing them. The new liquid-crystal 5-phenylpyrimidine derivatives have an S.sub.c or S.sup.*.sub.c phase and are described by the general formula (I) ##STR1## in which the symbols have the following meaning: R.sup.1 and R.sup.2 denote identical or different, straight-chain or branched alkyl or alkenyl groups having from k to 16 carbon atoms, with or without an asymmetric carbon atom, in which one or more non-adjacent --CH.sub.2 -- groups can be replaced by --O-- and /or --S----A and --B each denote ##STR2## in which the radicals R.sup.1, R.sup.2, in each case, are situated at the phenylene part of --A, --B and m and n denote 0 or 1, but m and n do not simultaneously denote 1, with the following provisos:(a) if m=n=0, k is 8, and in R.sup.2 the --CH.sub.2 -- group adjacent to the phenyl nucleus is replaced by --O--;(b) if m=1 and n=0, k is 2, and(c) if m=0 and n=1, k is 2 and in R.sup.2 the --CH.sub.2 -- group adjacent to the phenyl nucleus is replaced by --O--.
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:
Arylcarboxylates of 2-hydroxypropionates are known, amongst other compounds, as dopes for converting tilted smectic liquid-crystal phases into ferroelectric liquid-crystal phases.The novel chiral aryloxypropionates of the general formula ##STR1## are two-fold chiral and in which the symbols have the following meaning: R.sup.1 denotes a straight-chain alkyl or alkoxy radical having 1 to 16 carbon atoms or a branched alkyl or alkoxy radical having 4 to 16 carbon atoms, it being possible for one or two non-adjacent CH.sub.2 groups to be replaced by a sulfur and/or oxygen atom;A denotes one, two or three aromatic or heteroaromatic rings which are linked to one another directly or via one or two COO groups;B denotes a chemical bond or one or two aromatic or heteroaromatic rings which are linked directly to one another;R.sup.2(a) if B is a chemical bond, denotes an alkyl radical having 2 to 10 carbon atoms which contains an asymmetrical carbon atom which is substituted by CH.sub.3, halogen or a COOC.sub.2 H.sub.5 group, or an alkyl radical having 3 to 10 carbon atoms which contains two adjacent, asymmetrical carbon atoms of which one is substituted by halogen and the other by a CH.sub.3 group, or which, together with an O, form an oxirane ring, or(b) if B denotes one or two aromatic or heteroaromatic rings which are bonded directly to one another, denotes alkoxy radicals having the same number of carbon atoms and the same structure of the alkyl group as under (a).
摘要:
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.
摘要:
What is described is a surface stabilized ferroelectric liquid crystal display with a layer thickness of 1 to 10 .mu.m containing a ferroelectric liquid crystal mixture having a high spontaneous polarization of P.sub.s greater than 20 nC.multidot.cm.sup.31 2 and a natural helical pitch of less than one half of the layer thickness.
摘要:
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.