LIQUID-CRYSTALLINE MEDIA HAVING HOMEOTROPIC ALIGNMENT

Abstract

The present invention relates to liquid-crystalline media (LC media) comprising a low-molecular-weight component, a self-alignment additive comprising a thiol group and optionally a polymerizable component. The self-alignment additives effect homeotropic (vertical) alignment of the LC media at a surface or the cell walls of a liquid-crystal display (LC display). The invention therefore also encompasses LC displays having homeotropic alignment of the liquid-crystalline medium (LC medium) without alignment layers. The invention discloses novel structures for self-alignment additives which have a thiol functional groups.

Claims

1. A liquid-crystal (LC) medium comprising a low-molecular-weight, non-polymerizable liquid-crystalline component and one or more compounds of formula I
R.sup.1-[A.sup.3-Z.sup.3].sub.m[A.sup.2-Z.sup.2].sub.n-A.sup.1-R.sup.a(I) in which A.sup.1, A.sup.2, A.sup.3 each, independently of one another, denote an aromatic, heteroaromatic, alicyclic or heterocyclic group, which may also contain fused rings, and which may also be mono- or polysubstituted by a group L or -Sp-P, L in each case, independently of one another, denotes H, F, Cl, Br, I, CN, NO.sub.2, NCO, NCS, OCN, SCN, C(O)N(R.sup.0).sub.2, C(O)R.sup.0, optionally substituted silyl, optionally substituted aryl or cycloalkyl having 3 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, in which, in addition, one or more H atoms may each be replaced by F or Cl, P denotes a polymerizable group, Sp denotes a spacer group or a single bond, Z.sup.2, Z.sup.3 in each case, independently of one another, denotes a single bond, O, S, CO, COO, OCO, OCOO, OCH.sub.2, CH.sub.2O, SCH.sub.2, CH.sub.2S, CF.sub.2O, OCF.sub.2, CF.sub.2S, SCF.sub.2, (CH.sub.2).sub.n1, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, (CF.sub.2).sub.n1, CHCH, CFCF, CC, CHCHCOO, OCOCHCH, (CR.sup.0R.sup.00).sub.n1, CH(-Sp-P), CH.sub.2CH(-Sp-P), or CH(-Sp-P)CH(Sp-P), n1 denotes 1, 2, 3 or 4, m denotes 0, 1, 2, 3, 4, 5 or 6, n denotes 0 or 1, R.sup.0 in each case, independently of one another, denotes alkyl having 1 to 12 C atoms, R.sup.00 in each case, independently of one another, denotes H or alkyl having 1 to 12 C atoms, R.sup.1 denotes H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced by O, S, CO, COO, OCO, or OCOO in such a way that O and/or S atoms are not linked directly to one another and in which, in addition, one or more H atoms may each be replaced by F or Cl, or a group -Sp-P, R.sup.a denotes an anchor group of the formula ##STR00317## p denotes 1 or 2, q denotes 2 or 3, B denotes a substituted or unsubstituted ring system or condensed ring system, Y, independently of one another, denotes O, S, C(O), C(O)O, OC(O), NR.sup.11 or a single bond, o denotes 0 or 1, X.sup.1, independently of one another, denotes SH, H, alkyl or fluoroalkyl, where at least one group X.sup.1 denotes SH, R.sup.11 denotes alkyl having 1 to 12 C atoms, Sp.sup.a, Sp.sup.c, Sp.sup.d each, independently of one another, denote a spacer group or a single bond, and and Sp.sup.b denotes a tri- or tetravalent group.

2. LC medium according to claim 1, characterised in that it additionally comprises a polymerizable or polymerized component, where the polymerized component is obtainable by polymerization of a polymerizable component.

3. The medium according to claim 1, wherein, in formula I, A.sup.1, A.sup.2, A.sup.3 each, independently of one another, denote 1,4-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl, where, in addition, one or more CH groups in these groups may each be replaced by N, cyclohexane-1,4-diyl, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced by O or S, 3,3-bicyclobutylidene, 1,4-cyclohexenylene, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, piperidine-1,4-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, indane-2,5-diyl or octahydro-4,7-methanoindane-2,5-diyl, perhydrocyclopenta[a]phenanthrene-3,17-diyl (in particular gonane-3,17-diyl), where all these groups may be unsubstituted or mono- or polysubstituted by a group L or -Sp-P.

4. The medium according to claim 1, wherein the compound of the formula I is a compound of formula I1, ##STR00318## in which R.sup.1, R.sup.a, A.sup.1, A.sup.2, A.sup.3, Z.sup.2, Z.sup.3, L, m and n independently are as defined, and r1, r2, r3 independently denote 0, 1, 2 or 3.

5. The medium according to claim 1, wherein the one or more compounds of the formula I are selected from compounds of formulae IA, IB, IC, ID and IE: ##STR00319## in which R.sup.1, R.sup.a, Z.sup.2, Z.sup.3, L independently are as defined, and r1, r2, r3 independently denote 0, 1, 2 or 3.

6. The medium according to claim 1, wherein, besides said one or more compounds of formula I, said medium further comprises one or more compounds of formula IX,
R.sup.12-[A.sup.31-Z.sup.31].sub.m-[A.sup.21-Z.sup.21].sub.n-A.sup.11-R.sup.a1(IX) in which A.sup.11, A.sup.21, A.sup.31 each, independently of one another, denote an aromatic, heteroaromatic, alicyclic or heterocyclic group, which may also contain fused rings, and which may also be mono- or polysubstituted by a group L or -Sp-P, P denotes a polymerizable group, Sp denotes a spacer group or a single bond, Z.sup.21, Z.sup.31 in each case, independently of one another, denotes a single bond, O, S, CO, COO, OCO, OCOO, OCH.sub.2, CH.sub.2O, SCH.sub.2, CH.sub.2S, CF.sub.2O, OCF.sub.2, CF.sub.2S, SCF.sub.2, (CH.sub.2).sub.n1, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, (CF.sub.2).sub.n1, CHCH, CFCF, CC, CHCHCOO, OCOCHCH, (CR.sup.0R.sup.00).sub.n1, CH(-Sp-P), CH.sub.2CH(-Sp-P), or CH(-Sp-P)CH(-Sp-P), n1 denotes 1, 2, 3 or 4, L in each case, independently of one another, denotes H, F, Cl, Br, I, CN, NO.sub.2, NCO, NCS, OCN, SCN, C(O)N(R.sup.0).sub.2, C(O)R.sup.0, optionally substituted silyl, optionally substituted aryl or cycloalkyl having 3 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, in which, in addition, one or more H atoms may each be replaced by F or Cl, R.sup.0 in each case, independently of one another, denotes alkyl having 1 to 12 C atoms, and R.sup.00 in each case, independently of one another, denotes H or alkyl having 1 to 12 C atoms, m denotes 0, 1, 2, 3, 4, 5 or 6, n denotes 0 or 1, R.sup.12 denotes H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced by O, S, CO, COO, OCO, or OCOO in such a way that O and/or S atoms are not linked directly to one another and in which, in addition, one or more H atoms may each be replaced by F or Cl, or a group -Sp-P, R.sup.a1 denotes an anchor group of the formula ##STR00320## p denotes 1 or 2, q denotes 2 or 3, B denotes a substituted or unsubstituted ring system or condensed ring system, Y independently of one another, denotes O, S, C(O), C(O)O, OC(O), NR.sup.11 or a single bond, o denotes 0 or 1, X.sup.11, independently of one another, denotes H, alkyl, fluoroalkyl, OH, NH.sub.2, NHR.sup.11, NR.sup.11.sub.2, OR.sup.aa, C(O)OH, or CHO, where at least one group X.sup.1 denotes a radical selected from OH, NH.sub.2, NHR.sup.11, C(O)OH and CHO, R.sup.11 denotes alkyl having 1 to 12 C atoms, Sp.sup.a, Sp.sup.c, Sp.sup.d each, independently of one another, denote a spacer group or a single bond, and Sp.sup.b denotes a tri- or tetravalent group, preferably CH, N or C.

7. The medium according to claim 1, wherein said one or more compounds of formula I comprise one or more compounds selected from the following formulae IA to IE: ##STR00321## in which L, R.sup.a and Z.sup.2 independently are as defined in claim 1, and Z.sup.3 denotes a single bond or CH.sub.2CH.sub.2, r1, r2, r3 independently denote 0, 1, 2 or 3, and R.sup.1 denotes H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced by O, S, CO, COO, OCO, or OCOO in such a way that O and/or S atoms are not linked directly to one another and in which, in addition, one or more H atoms may each be replaced by F or Cl.

8. The medium according to claim 1, wherein group R.sup.a in formula I contains one, two or three SH groups.

9. The medium according to claim 1, wherein group R.sup.a denotes a group selected from
Sp.sup.a-X.sup.1 and ##STR00322## in which Sp.sup.a, Sp.sup.b, Sp.sup.c, p and X.sup.1 have the meaning as defined in claim 1.

10. The medium according to claim 1, wherein group R.sup.a denotes a group selected from the following part-formulae: ##STR00323##

11. The medium according to claim 1, wherein, for the compound of the formula I, Z.sup.2 is a single bond.

12. The medium according to claim 1, wherein said medium comprises compounds of formula I in a concentration of less than 10% by weight.

13. The medium according to claim 1, wherein said medium comprises one or more polymerizable compounds of formula M or a (co)polymer comprising compounds of formula M:
P.sup.1-Sp.sup.1-A.sup.2-(Z.sup.1-A.sup.1).sub.n-Sp.sup.2-P.sup.2M in which the individual radicals have the following meanings: P.sup.1, P.sup.2 each independently denote a polymerizable group, Sp.sup.1, Sp.sup.2 each independently denote a spacer group, A.sup.1, A.sup.2 each, independently of one another, denote a radical selected from the following groups: a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene and 4,4-bicyclohexylene, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced by O or S and in which, in addition, one or more H atoms may each be replaced by a group L, or selected from ##STR00324## b) the group consisting of 1,4-phenylene and 1,3-phenylene, in which, in addition, one or two CH groups may each be replaced by N and in which, in addition, one or more H atoms may each be replaced by a group L or -Sp.sup.3-P, c) the group consisting of tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by a group L, d) the group consisting of saturated, partially unsaturated or fully unsaturated, and optionally substituted, polycyclic radicals having 5 to 20 cyclic C atoms, one or more of which may, in addition, be replaced by heteroatoms, preferably selected from the group consisting of bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, ##STR00325## ##STR00326## where, in addition, one or more H atoms in these radicals may each be replaced by a group L or -Sp.sup.3-P, and/or one or more double bonds may each be replaced by single bonds, and/or one or more CH groups may each be replaced by N, P.sup.3 denotes a polymerizable group, Sp.sup.3 denotes a spacer group, n denotes 0, 1, 2 or 3, Z.sup.1 in each case, independently of one another, denotes COO, OCO, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2, (CH.sub.2).sub.n where n is 2, 3 or 4, O, CO, C(R.sup.cR.sup.d), CH.sub.2CF.sub.2, CF.sub.2CF.sub.2 or a single bond, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF.sub.5 or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, M denotes O, S, CH.sub.2, CHY.sup.1 or CY.sup.1Y.sup.2, Y.sup.1 and Y.sup.2 each, independently of one another, have one of the meanings indicated above for R.sup.0 or denote Cl or CN, W.sup.1, W.sup.2 each, independently of one another, denote CH.sub.2CH.sub.2, CHCH, CH.sub.2O, OCH.sub.2, C(R.sup.cR.sup.d) or O, R.sup.c and R.sup.d each, independently of one another, denote H, F, CF.sub.3, or alkyl having 1 to 6 C atoms, preferably H, methyl or ethyl, where one or more of the groups P.sup.1Sp.sup.1-, -Sp.sup.2-P.sup.2 and -Sp.sup.3-P.sup.3 may denote a radical R.sup.aa, with the proviso that at least one of the groups P.sup.1Sp.sup.1-, -Sp.sup.2-P.sup.2 and -Sp.sup.3-P.sup.3 present does not denote R.sup.aa, R.sup.aa denotes H, F, Cl, CN or straight-chain or branched alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced, independently of one another, by C(R.sup.0)C(R.sup.0), CC, O, S, CO, COO, OCO, or OCOO in such a way that O and/or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may each be replaced by F, Cl, CN or P.sup.1Sp.sup.1-, where the groups OH, NH.sub.2, SH, NHR, C(O)OH and CHO are not present in R.sup.aa, and R.sup.0, R.sup.00 each, independently of one another, denote H, F or straight-chain or branched alkyl having 1 to 12 C atoms, in which, in addition, one or more H atoms each may be replaced by F.

14. The medium according to claim 13, wherein the polymerizable or polymerized component comprises 0.01 to 5% by weight of one or more compounds of the formula M.

15. A liquid-crystal (LC) display comprising an LC cell having two substrates and at least two electrodes, where at least one substrate is transparent to light and at least one substrate has one or two electrodes, and having a layer of an LC medium according to claim 1 located between the substrates, where the compound of the formula I is suitable for effecting homeotropic alignment of the LC medium with respect to the substrate surfaces.

16. The display according to claim 15, wherein the substrates have no alignment layers for homeotropic alignment.

17. The display according to claim 15, wherein one or two of the substrates is coated with indium-tin oxide.

18. The display according to claim 15, wherein said display is a VA display containing an LC medium having negative dielectric anisotropy and electrodes arranged on opposite substrates.

19. A process for the preparation of a liquid-crystal medium, said process comprising mixing one or more compounds of the formula I according to claim 1 with a low-molecular-weight liquid-crystalline component, and optionally one or more polymerizable compounds, and/or one or more compounds of the formula IX, and/or other additives are added.

20. A compound of formula I
R.sup.1-[A.sup.3-Z.sup.3].sub.m-[A.sup.2-Z.sup.2].sub.n-A.sup.1-R.sup.a(I) in which A.sup.1, A.sup.2, A.sup.3 each, independently of one another, denote an aromatic, heteroaromatic, alicyclic or heterocyclic group, which may also contain fused rings, and which may also be mono- or polysubstituted by a group L or -Sp-P, L in each case, independently of one another, denotes H, F, Cl, Br, I, CN, NO.sub.2, NCO, NCS, OCN, SCN, C(O)N(R.sup.0).sub.2, C(O)R.sup.0, optionally substituted silyl, optionally substituted aryl or cycloalkyl having 3 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, in which, in addition, one or more H atoms may each be replaced by F or Cl, P denotes a polymerizable group, Sp denotes a spacer group or a single bond, Z.sup.2 in each case, independently of one another, denotes O, S, CO, COO, OCO, OCOO, OCH.sub.2, CH.sub.2O, SCH.sub.2, CH.sub.2S, CF.sub.2O, OCF.sub.2, CF.sub.2S, SCF.sub.2, (CH.sub.2).sub.n1, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, (CF.sub.2).sub.n1, CHCH, CFCF, CC, CHCHCOO, OCOCHCH, (CR.sup.0R.sup.00).sub.n1, CH(-Sp-P), CH.sub.2CH(-Sp-P), or CH(-Sp-P)CH(-Sp-P), Z.sup.3 in each case, independently of one another, denotes a single bond, O, S, CO, COO, OCO, OCOO, OCH.sub.2, CH.sub.2O, SCH.sub.2, CH.sub.2S, CF.sub.2O, OCF.sub.2, CF.sub.2S, SCF.sub.2, (CH.sub.2).sub.n1, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, (CF.sub.2).sub.n1, CHCH, CFCF, CC, CHCHCOO, OCOCHCH, (CR.sup.0R.sup.00).sub.n1, CH(-Sp-P), CH.sub.2CH(-Sp-P), or CH(-Sp-P)CH(-Sp-P), n1 denotes 1, 2, 3 or 4, m denotes 1, 2, 3, 4, 5 or 6, n denotes 1, R.sup.0 in each case, independently of one another, denotes alkyl having 1 to 12 C atoms, R.sup.00 in each case, independently of one another, denotes H or alkyl having 1 to 12 C atoms, R.sup.1, independently of one another, denotes H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH.sub.2 groups may each be replaced by O, S, CO, COO, OCO, or OCOO in such a way that O and/or S atoms are not linked directly to one another and in which, in addition, one or more H atoms may each be replaced by F or Cl, or a group -Sp-P, R.sup.a denotes an anchor group of the formula ##STR00327## p denotes 1 or 2, q denotes 2 or 3, B denotes a substituted or unsubstituted ring system or condensed ring system, Y, independently of one another, denotes O, S, C(O), C(O)O, OC(O), NR.sup.11 or a single bond, o denotes 0 or 1, X.sup.1, independently of one another, denotes SH, H, alkyl, fluoroalkyl, OH, NH.sub.2, NHR.sup.11, NR.sup.11.sub.2, OR.sup.11, C(O)OH, CHO, where at least one group X.sup.1 denotes a SH, R.sup.11 denotes alkyl having 1 to 12 C atoms, Sp.sup.a, Sp.sup.c, Sp.sup.d each, independently of one another, denote a spacer group or a single bond, and Sp.sup.b denotes a tri- or tetravalent group.

21. A compound according to claim 20, wherein m is 1.

22. A compound according to claim 21, wherein A.sup.1 and A.sup.2 independently denote 1,4-phenylene or cyclohexane-1,4-diyl, each of which may be mono- or polysubstituted by a group L or -Sp-P.

23. A method for effecting homeotropic alignment of a liquid-crystal medium with respect to a surface delimiting the liquid-crystal medium, comprising adding to said medium one or more compounds of formula I according to claim 1.

24. A process for the production of an LC display comprising an LC cell having two substrates and at least two electrodes, where at least one substrate is transparent to light and at least one substrate has one or two electrodes, said process comprising the steps: filling of the cell with a liquid-crystal medium according to claim 1, where homeotropic alignment of the liquid-crystal medium with respect to the substrate surfaces is established, optionally heating the medium, and optionally polymerizing the polymerizable component(s), optionally with application of a voltage to the cell or under the action of an electric field, in one or more process steps.

Description

EXAMPLES

[0253] The compounds employed, if not commercially available, are synthesized by standard laboratory procedures. The LC media originate from Merck KGaA, Germany.

A) Synthesis Examples

Example 1

Synthesis of 2-{4-[4-(4-ethylcyclohexyl)cyclohexyl]-2,3-difluorophenoxy}ethane-1-thiol 1

[0254] ##STR00308##

1) Synthesis of 1-[2-(benzyloxy)ethoxy]-4-[4-(4-ethylcyclohexyl)-cyclohexyl]-2,3-difluorobenzene A

[0255] ##STR00309##

[0256] 23.0 g (71.3 mmol) 4-[4-(4-ethylcyclohexyl)cyclohexyl]-2,3-difluoro-phenole, 20.0 g (90.0 mmol) (2-Brom-ethoxymethyl)benzene and 25.0 g (181 mmol) K.sub.2CO.sub.2 are solved in 500 mL methyl ethyl ketone and are refluxed for 16 h. The reaction mixture is filtered and further purified by column chromatography with toluene over 500 mL silica gel. The reaction product is concentrated under vacuum and further crystallized out of 400 mL ethanol to yield the product (27.5 g) as colourless crystals.

2) Synthesis of 2-{4-[4-(4-ethylcyclohexyl)cyclohexyl]-2,3-difluorophenoxy}ethane-1-ol

[0257] ##STR00310##

[0258] 27.4 g (59.9 mmol) A are solved in 300 mL tetrahydrofuran, 2.70 g (PdC-5% E101 R [54% water]) are added and the reaction mixture is stirred under 1 bar hydrogen atmosphere for 16 h at room temperature. The reaction mixture is filtered and evaporated under vacuum to yield the reaction product (21.2 g) as colourless crystals.

3) Synthesis of 2-{4-[4-(4-ethylcyclohexyl)cyclohexyl]-2,3-difluorophenoxy}ethyl methanesulfonate C

[0259] ##STR00311##

[0260] 17.0 g (46.4 mmol) alcohol B and 500 mg (4.10 mmol) of 4-(dimethylamino)pyridine are dissolved in 200 mL dichloromethane and 8.0 mL (99.1 mmol) pyridine are added dropwise at 17-18 C. The reaction mixture is cooled to 3-4 C. and 4.0 mL (51.6 mmol) methanesufonyl-chloride are added slowly dropwise. The reaction mixture is stirred for 16 h at room temperature and cautiously treated with 2N HCl and further stirred for 1 h. The layers are separated, the water layer is extracted with dichloromethane and the combined organic layers are dried over Na.sub.2SO.sub.2, filtered and evaporated under vacuum. The resulting product is purified by column chromatography with dichloromethane over 400 g silica gel. The resulting product is evaporated under vacuum and crystallized out of acetonitrile at 20 C. to yield the product (20.6 g) as colourless crystals.

4) Synthesis of 1-[(2-{4-[4-(4-ethylcyclohexyl)cyclohexyl]-2,3-difluorophenoxy}ethyl)sulfanyl]ethan-1-one

[0261] ##STR00312##

[0262] 5.0 g (11.2 mmol) C and 10.0 g (87.6 mmol) of potassium-thioacetate are dissolved in 100 mL N,N-Dimethylformamide and stirred for 1 h at room temperature. The reaction mixture is cautiously poured in water and extracted with toluene. The combined organic layers are washed with brine, dried over Na.sub.2SO.sub.4, filtered and evaporated under vacuum. The obtained product is crystallized out of 100 mL acetonitrile at 5 C. to yield the product (3.5 g) as slightly yellow crystals.

5) Synthesis of 2-{4-[4-(4-ethylcyclohexyl)cyclohexyl]-2,3-difluorophenoxy}ethane-1-thiol 1

[0263] ##STR00313##

[0264] 3.40 g (8.01 mmol) D are suspended in 150 mL of methanol, cooled to 2-3 C. and dropwise added with 7.0 ml of sodium methylate (30% solution in methanol). The reaction mixture is stirred for 30 min and cautiously neutralized with glacial acetic acid. The mixture is extracted with methyl-tertbutyl ether, washed with brine, dried over Na.sub.2SO.sub.4, filtered and evaporated under vacuum. The product is purified via column chromatography with heptane/toluene (8:2) over 150 mL silica gel. The obtained product is evaporated under vacuum and crystallized out of heptane at 25 C. to yield the product (1.8 g) as colourless crystals.

[0265] Phases: Tm 58 C./SmB 59 C./N 60.0 C. isotropic.

[0266] MS(EI): M.sup.+=382.3

[0267] .sup.1H NMR (500 MHz, DMSO-d6):

[0268] =0.85 (t.sub.(overlapped with multiplet), 7.51 Hz, 5H, CH.sub.3, CH.sub.2), 0.92-1.09 (m, 4H, CH.sub.2), 1.21-1.10 (m, 5H, CH.sub.2, CH), 1.43 (me, 2H, CH.sub.2), 1.84-1.68 (m, 8H, CH.sub.2), 2.49 (t, 8.27 Hz.sub.(overlapped with DMSO), 1 H, SH), 2.67 (me, 1H, CH), 2.84 (m, 2H, CH.sub.2S), 4.14 (t, 6.63 Hz, 2H, OCH.sub.2), 6.48 (dt, 8.30, 1.23 Hz, 1H, arom.-H), 7.01 (dt, 8.20, 1.57 Hz, 1H, arom.-H).

B) Mixture Examples

[0269] LC media according to the invention are prepared using the following liquid-crystalline mixtures consisting of low-molecular-weight components in the percentage proportions by weight indicated.

H1: Nematic Host Mixture (<0)

[0270]

TABLE-US-00006 CY-3-O2 15.50% Clearing point [ C.]: 75.1 CCY-3-O3 8.00% n [589 nm, 20 C.]: 0.098 CCY-4-O2 10.00% [1 kHz, 20 C.]: 3.0 CPY-2-O2 5.50% .sub.|| [1 kHz, 20 C.]: 3.4 CPY-3-O2 11.50% .sub. [1 kHz, 20 C.]: 6.4 CCH-34 9.25% K.sub.1 [pN, 20 C.]: 13.1 CCH-23 24.50% K.sub.3 [pN, 20 C.]: 13.3 PYP-2-3 8.75% .sub.1 [mPa .Math. s, 20 C.]: 113 PCH-3O1 7.00% V.sub.0 [20 C., V]: 2.22

H2: Nematic Host Mixture (<0)

[0271]

TABLE-US-00007 CY-3-O4 14.00% Clearing point [ C.]: 80.0 CCY-3-O2 9.00% n [589 nm, 20 C.]: 0.090 CCY-3-O3 9.00% [1 kHz, 20 C.]: 3.3 CPY-2-O2 10.00% .sub.|| [1 kHz, 20 C.]: 3.4 CPY-3-O2 10.00% .sub. [1 kHz, 20 C.]: 6.7 CCY-3-1 8.00% K.sub.1 [pN, 20 C.]: 15.1 CCH-34 9.00% K.sub.3 [pN, 20 C.]: 14.6 CCH-35 6.00% .sub.1 [mPa .Math. s, 20 C.]: 140 PCH-53 10.00% V.sub.0 [20 C., V]: 2.23 CCH-3O1 6.00% CCH-3O3 9.00%

H3: Nematic Host Mixture (<0)

[0272]

TABLE-US-00008 CC-3-V1 9.00% Clearing point [ C.]: 74.7 CCH-23 18.00% n [589 nm, 20 C.]: 0.098 CCH-34 3.00% [1 kHz, 20 C.]: 3.4 CCH-35 7.00% .sub.|| [1 kHz, 20 C.]: 3.5 CCP-3-1 5.50% .sub. [1 kHz, 20 C.]: 6.9 CCY-3-O2 11.50% K.sub.1 [pN, 20 C.]: 14.9 CPY-2-O2 8.00% K.sub.3 [pN, 20 C.]: 15.9 CPY-3-O2 11.00% .sub.1 [mPa .Math. s, 20 C.]: 108 CY-3-O2 15.50% V.sub.0 [20 C., V]: 2.28 PY-3-O2 11.50%

H4: Nematic Host Mixture (<0)

[0273]

TABLE-US-00009 CC-3-V 37.50% Clearing point [ C.]: 74.8 CC-3-V1 2.00% n [589 nm, 20 C.]: 0.099 CCY-4-O2 14.50% [1 kHz, 20 C.]: 2.9 CPY-2-O2 10.50% .sub.|| [1 kHz, 20 C.]: 3.7 CPY-3-O2 9.50% .sub. [1 kHz, 20 C.]: 6.6 CY-3-O2 15.00% K.sub.1 [pN, 20 C.]: 12.2 CY-3-O4 4.50% K.sub.3 [pN, 20 C.]: 13.4 PYP-2-4 5.50% .sub.1 [mPa .Math. s, 20 C.]: 92 PPGU-3-F 1.00% V.sub.0 [20 C., V]: 2.28

H5: Nematic Host Mixture (<0)

[0274]

TABLE-US-00010 CCH-23 20.00% Clearing point [ C.]: 74.8 CCH-3O1 6.00% n [589 nm, 20 C.]: 0.105 CCH-34 6.00% [1 kHz, 20 C.]: 3.2 CCP-3-1 3.00% .sub.|| [1 kHz, 20 C.]: 3.5 CCY-3-O2 11.00% .sub. [1 kHz, 20 C.]: 6.8 CPY-2-O2 12.00% K.sub.1 [pN, 20 C.]: 12.7 CPY-3-O2 11.00% K.sub.3 [pN, 20 C.]: 13.6 CY-3-O2 14.00% .sub.1 [mPa .Math. s, 20 C.]: 120 CY-3-O4 4.00% V.sub.0 [20 C., V]: 2.16 PCH-3O1 4.00% PYP-2-3 9.00%

H6: Nematic Host Mixture (<0)

[0275]

TABLE-US-00011 CC-4-V 17.00% Clearing point [ C.]: 106.1 CCP-V-1 15.00% n [589 nm, 20 C.]: 0.120 CCPC-33 2.50% [1 kHz, 20 C.]: 3.6 CCY-3-O2 4.00% .sub.|| [1 kHz, 20 C.]: 3.5 CCY-3-O3 5.00% .sub. [1 kHz, 20 C.]: 7.0 CCY-4-O2 5.00% K.sub.1 [pN, 20 C.]: 16.8 CLY-3-O2 3.50% K.sub.3 [pN, 20 C.]: 17.3 CLY-3-O3 2.00% .sub.1 [mPa .Math. s, 20 C.]: 207 CPY-2-O2 8.00% V.sub.0 [20 C., V]: 2.33 CPY-3-O2 10.00% CY-3-O4 17.00% PYP-2-3 11.00%

H7: Nematic Host Mixture (<0)

[0276]

TABLE-US-00012 CY-3-O2 15.00% Clearing point [ C.]: 75.5 CCY-4-O2 9.50% n [589 nm, 20 C.]: 0.108 CCY-5-O2 5.00% [1 kHz, 20 C.]: 3.0 CPY-2-O2 9.00% .sub.|| [1 kHz, 20 C.]: 3.5 CPY-3-O2 9.00% .sub. [1 kHz, 20 C.]: 6.5 CCH-34 9.00% K.sub.1 [pN, 20 C.]: 12.9 CCH-23 22.00% K.sub.3 [pN, 20 C.]: 13.0 PYP-2-3 7.00% .sub.1 [mPa .Math. s, 20 C.]: 115 PYP-2-4 7.50% V.sub.0 [20 C., V]: 2.20 PCH-3O1 7.00%

H8: Nematic Host Mixture (<0)

[0277]

TABLE-US-00013 CY-3-O2 15.00% Clearing point [ C.]: 74.7 CY-5-O2 6.50% n [589 nm, 20 C.]: 0.108 CCY-3-O2 11.00% [1 kHz, 20 C.]: 3.0 CPY-2-O2 5.50% .sub.|| [1 kHz, 20 C.]: 3.6 CPY-3-O2 10.50% .sub. [1 kHz, 20 C.]: 6.6 CC-3-V 28.50% K.sub.1 [pN, 20 C.]: 12.9 CC-3-V1 10.00% K.sub.3 [pN, 20 C.]: 15.7 PYP-2-3 12.50% .sub.1 [mPa .Math. s, 20 C.]: 97 PPGU-3-F 0.50% V.sub.0 [20 C., V]: 2.42

H9: Nematic Host Mixture (<0)

[0278]

TABLE-US-00014 CCH-35 9.50% Clearing point [ C.]: 79.1 CCH-5O1 5.00% n [589 nm, 20 C.]: 0.091 CCY-2-1 9.50% [1 kHz, 20 C.]: 3.6 CCY-3-1 10.50% .sub.|| [1 kHz, 20 C.]: 3.5 CCY-3-O2 10.50% .sub. [1 kHz, 20 C.]: 7.1 CCY-5-O2 9.50% K.sub.1 [pN, 20 C.]: 14.6 CPY-2-O2 12.00% K.sub.3 [pN, 20 C.]: 14.5 CY-3-O4 9.00% .sub.1 [mPa .Math. s, 20 C.]: 178 CY-5-O4 11.00% V.sub.0 [20 C., V]: 2.12 PCH-53 13.50%

H10: Nematic Host Mixture (<0)

[0279]

TABLE-US-00015 BCH-32 4.00% Clearing point [ C.]: 74.8 CC-3-V1 8.00% n [589 nm, 20 C.]: 0.106 CCH-23 13.00% [1 kHz, 20 C.]: 3.5 CCH-34 7.00% .sub.|| [1 kHz, 20 C.]: 3.6 CCH-35 7.00% .sub. [1 kHz, 20 C.]: 7.1 CCY-3-O2 13.00% K.sub.1 [pN, 20 C.]: 14.8 CPY-2-O2 7.00% K.sub.3 [pN, 20 C.]: 15.8 CPY-3-O2 12.00% .sub.1 [mPa .Math. s, 20 C.]: 115 CY-3-O2 12.00% V.sub.0 [20 C., V]: 2.23 PCH-3O1 2.00% PY-3-O2 15.00%

H11: Nematic Host Mixture (<0)

[0280]

TABLE-US-00016 CY-3-O4 22.00% Clearing point [ C.]: 86.9 CY-5-O4 12.00% n [589 nm, 20 C.]: 0.111 CCY-3-O2 6.00% [1 kHz, 20 C.]: 4.9 CCY-3-O3 6.00% .sub.|| [1 kHz, 20 C.]: 3.8 CCY-4-O2 6.00% .sub. [1 kHz, 20 C.]: 8.7 CPY-2-O2 10.00% K.sub.1 [pN, 20 C.]: 14.9 CPY-3-O2 10.00% K.sub.3 [pN, 20 C.]: 15.9 PYP-2-3 7.00% .sub.1 [mPa .Math. s, 20 C.]: 222 CC-3-V1 7.00% V.sub.0 [20 C., V]: 1.91 CC-5-V 10.00% CCPC-33 2.00% CCPC-35 2.00%

H12: Nematic Host Mixture (<0)

[0281]

TABLE-US-00017 CY-3-O4 12.00% Clearing point [ C.]: 86.0 CY-5-O2 10.00% n [589 nm, 20 C.]: 0.110 CY-5-O4 8.00% [1 kHz, 20 C.]: 5.0 CCY-3-O2 8.00% .sub.|| [1 kHz, 20 C.]: 3.8 CCY-4-O2 7.00% .sub. [1 kHz, 20 C.]: 8.8 CCY-5-O2 6.00% K.sub.1 [pN, 20 C.]: 14.7 CCY-2-1 8.00% K.sub.3 [pN, 20 C.]: 16.0 CCY-3-1 7.00% .sub.1 [mPa .Math. s, 20 C.]: 250 CPY-3-O2 9.00% V.sub.0 [20 C., V]: 1.90 CPY-3-O2 9.00% BCH-32 6.00% PCH-53 10.00%

H13: Nematic Host Mixture (<0)

[0282]

TABLE-US-00018 CC-3-V1 10.25% Clearing point [ C.]: 74.7 CCH-23 18.50% n [589 nm, 20 C.]: 0.103 CCH-35 6.75% [1 kHz, 20 C.]: 3.1 CCP-3-1 6.00% .sub.|| [1 kHz, 20 C.]: 3.4 CCY-3-1 2.50% .sub. [1 kHz, 20 C.]: 6.4 CCY-3-O2 12.00% K.sub.1 [pN, 20 C.]: 15.4 CPY-2-O2 6.00% K.sub.3 [pN, 20 C.]: 16.8 CPY-3-O2 9.75% .sub.1 [mPa .Math. s, 20 C.]: 104 CY-3-O2 11.50% V.sub.0 [20 C., V]: 2.46 PP-1-2V1 3.75% PY-3-O2 13.00%

H14: Nematic Host Mixture (<0)

[0283]

TABLE-US-00019 CC-3-V 27.50% Clearing point [ C.]: 74.7 CC-3-V1 10.00% n [589 nm, 20 C.]: 0.104 CCH-35 8.00% [1 kHz, 20 C.]: 3.0 CCY-3-O2 9.25% .sub.|| [1 kHz, 20 C.]: 3.4 CLY-3-O2 10.00% .sub. [1 kHz, 20 C.]: 6.4 CPY-3-O2 11.75% K.sub.1 [pN, 20 C.]: 15.3 PY-3-O2 14.00% K.sub.3 [pN, 20 C.]: 16.2 PY-4-O2 9.00% .sub.1 [mPa .Math. s, 20 C.]: 88 PYP-2-4 0.50% V.sub.0 [20 C., V]: 2.44

[0284] The following self-alignment additives are particularly used:

TABLE-US-00020 Self-alignment additive No. Structure 1 [00314] 2 [00315]

[0285] Compound 2 is commercially available from Angene (England).

[0286] The following polymerizable compound is used:

##STR00316##

Mixture Example 1

[0287] Self-alignment additive 1 (2.0% by weight) is added to a nematic LC medium H1 of the VA type (<0) and the mixture is homogenized.

[0288] Low temperature stability (LTS) in a glass flask (20 C., 1000 h): Passed. The LTS value is strongly improved over mixtures doped with the equivalent additive substituted with a hydroxyl group.

Use in Test Cells without Pre-Alignment Layer:

[0289] The mixture formed is introduced into a test cell (without polyimide alignment layer, layer thickness d=4.0 m, ITO coated center on both sides, without passivation layer). The LC medium initially has partial spontaneous homeotropic (vertical) alignment with respect to the substrate surfaces. After heat treatment of the cell at 120 C. for 1 h, complete vertical alignment is observed between the ITO coated regions (dark region) of the cell, while the remaining part with pure glass substrates remains planar aligned (bright region). This alignment remains stable up to the clearing point, and the VA cell formed can be switched reversibly by application of a voltage.

V-T-Curve at Different Temperatures:

[0290] Voltage versus transmittance (0-10 V) was measured at various temperatures (20, 40, 60 C.). Switching is stable up to 60 C. and no hysteresis of the curves is observed even at higher temperatures. The performance was not diminished after heat stress or electric stress, which indicates a good long-term stability.

Mixture Example 2

[0291] Self-alignment additive 2 (5.0% by weight) and RM-1 (0.2% by weight) are added to a nematic LC medium H7 of the VA-type (<0) and the mixture is homogenized.

[0292] Low temperature stability (LTS) in a glass flask (25 C., 120 h): Passed.

Use in Test Cells without Pre-Alignment Layer:

[0293] The mixture formed is introduced into a test cell (as in Mixture Example 1). The LC medium initially has no spontaneous homeotropic (vertical) alignment with respect to the substrate surfaces. After heat treatment of the cell at 120 C. for 1 h, complete vertical alignment is observed between the ITO coated regions (dark region) of the cell, while the remaining part with pure glass substrates remains planar aligned (bright region). This alignment remains stable up to the clearing point, and the VA cell formed can be switched reversibly by application of a voltage.

Mixture Example 3: Polymer Stabilization of Mixture Example 2

[0294] Self-alignment additive 2 (5.0% by weight) and RM-1 (0.2% by weight) are added to a nematic LC medium H7 of the VA-type (<0) and the mixture is homogenized.

Polymer Stabilization:

[0295] The mixture formed is introduced into a test cell (as in Mixture Example 2). The LC medium initially has no spontaneous homeotropic (vertical) alignment with respect to the substrate surfaces. After heat treatment of the cell at 120 C. for 1 h complete vertical alignment is observed between the ITO coated regions (dark region) of the cell. UV-curing process is performed by applying 6 J of UV light (50 mW/cm.sup.2, 120 s) under the application of an electric field of 14 Vpp 60 Hz. The quality of the vertical alignment is not affected by the UV-step.

V-T-Curve at Different Temperatures:

[0296] Voltage versus transmittance (0-30 V) was measured at various temperatures (20, 40, 60, 70 C.). Switching is stable up to 70 C. and no hysteresis of the curves is observed even at higher temperatures.