Liquid-crystal displays and liquid-crystalline media having homeotropic alignment

Abstract

The present invention relates to liquid-crystalline media (LC media) having negative or positive dielectric anisotropy comprising self-alignment additives (SAMs) with an at least one bifunctional or polyfunctional anchor group, which effects the 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 conventional imide alignment layers. The LC media may be supplemented by a polymerizable or polymerized component, which serves for stabilization of the alignment, for adjustment of the tilt angle and/or as passivation layer.

Claims

1. A LC medium comprising a low-molecular-weight liquid-crystalline mixture and one or more self-aligning additives of formula I:
R.sup.1-A.sup.1-(Z.sup.2-A.sup.2).sub.m1-R.sup.2  (I) R.sup.2 denotes a group ##STR00255## Sp.sup.1, Sp.sup.3, Sp.sup.5 independently of each other, denotes a spacer group or a single bond, Sp.sup.2 denotes a trivalent, acyclic spacer group, Sp.sup.4 denotes a tetravalent, acyclic spacer group, Y is independently of each other O, S, (CO), NR.sup.0 or a single bond, X.sup.1 and X.sup.2 independently of each other a group —OH, —NH.sub.2, —NHR.sup.11, —SH, —SR.sup.11, —NR.sup.11.sub.2, —OR.sup.11 or —(CO)OH, ##STR00256## R.sup.11 in each case independently denotes a halogenated or unsubstituted alkyl chain having 1 to 15 C atoms, in which one or more CH.sub.2 groups are each optionally replaced, independently of one another, by —C≡C—, —CH═CH—, —(CO)O—, —O(CO)—, —(CO)— or —O— in such a way that O or N atoms are not linked directly to one another, and where two radicals R.sup.11 are optionally linked to one another to form a ring, B a ring or condensed ring, optionally substituted by one, two or three R.sup.L, p is 2, 3, 4 or 5, A.sup.1 and A.sup.2 each, independently of one another, denote an aromatic, heteroaromatic, alicyclic or heterocyclic group, which optionally contains fused rings, and which is optionally mono- or polysubstituted by R.sup.L, R.sup.L in each case, independently of one another, denotes OH, SH, SR.sup.0, —(CH.sub.2).sub.n1—OH, 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, —N(R.sup.0).sub.2, —(CH.sub.2).sub.n1—N(R.sup.0).sub.2, optionally substituted silyl, optionally substituted aryl or cycloalkyl having 6 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, in which one or more H atoms are optionally replaced by F or Cl, and two vicinal R.sup.L together are optionally ═O, n1 denotes 1, 2, 3, 4 or 5, Z.sup.2 in each case, independently of one another, denotes a single bond, —O—, —S—, —CO—, —CO—O—, —OCO—, —O—CO—O—, —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—, —CH═CH—, —CF═CF—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH— or CR.sup.0R.sup.00, R.sup.0 and R.sup.00 each, independently of one another, denote 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 one or more non-adjacent CH.sub.2 groups are optionally replaced by —C≡C, —CH═CH, —NR.sup.0—, —O—, —S—, —CO—, —CO—O—, —O—CO—, or —O—CO—O— in such a way that N, O and/or S atoms are not linked directly to one another, and in which one or more tertiary carbon atoms (CH groups) are optionally replaced by N, and in which one or more H atoms are optionally replaced by F or Cl, and m1 denotes 0, 1, 2, 3, 4 or 5.

2. The LC medium according to claim 1, further comprising a polymerizable or polymerized component, where the polymerized component is obtainable by polymerization of a polymerizable component.

3. The LC medium according to claim 1, wherein in the compound of formula I, m1 is 1, 2 or 3.

4. The LC medium according to claim 1, wherein, in the compound of formula I, R.sup.2 contains two or three hydroxy groups.

5. The LC medium according to claim 1, wherein in the compound of formula I, R.sup.2 comprises two groups X.sup.1 or two groups X.sup.2.

6. The LC medium according to claim 1, wherein, in the compound of formula I, A.sup.1 and A.sup.2, if present, are independently 1,4-phenylene and/or cyclohexane-1,4-diyl, which are all optionally substituted by R.sup.L.

7. The LC medium according to claim 1, wherein, in the compound of formula I, Sp.sup.2 is CH, CR.sup.0 or N, Sp.sup.4 is C, and ##STR00257## denotes a benzene ring.

8. The LC medium according to claim 1, wherein in the compound of formula I R.sup.2 denotes ##STR00258## in which Y, X.sup.1, X.sup.2, Sp.sup.1 and Sp.sup.3 are independently defined as for the compound of formula I, and n independently denotes 1, 2, 3 or 4.

9. The LC medium according to claim 1, comprising one or more compounds of the following formulae: ##STR00259## ##STR00260## ##STR00261## ##STR00262## ##STR00263## ##STR00264## wherein R.sup.1, R.sup.L and p are independently defined as for the compound of formula I.

10. The LC medium according to claim 1, comprising the one or more compounds of formula I in a concentration of less than 1% by weight.

11. The LC medium according to claim 1, comprising one or more polymerizable compounds or a polymerized component, which comprises one or more compounds in polymerized form, wherein the one or more polymerizable compounds are of the following formulae: ##STR00265## ##STR00266## ##STR00267## ##STR00268## ##STR00269## ##STR00270## wherein P.sup.1 and P.sup.2 each, independently of one another, denote a polymerisable group, Sp.sup.1 and Sp.sup.2 each, independently of one another, denote a single bond or a divalent spacer group, where, in addition, one or more of the radicals P.sup.1-Sp.sup.1- and P.sup.2—Sp.sup.2- optionally denote a radical R.sup.aa, with the proviso that at least one of the radicals P.sup.1-Sp.sup.1- and P.sup.2—Sp.sup.2- 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 one or more non-adjacent CH.sub.2 groups are each optionally replaced, independently of one another, by C(R.sup.0)═C(R.sup.00)—, —C≡C—, —N(R.sup.0)—, —O—, —S—, —CO—, —CO—O—, —O—CO—, or —O—CO—O— in such a way that O and/or S atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by F, Cl, CN or P.sup.1—Sp.sup.1-, R.sup.0, R.sup.00 each, independently of one another, denote H or alkyl having 1 to 12 C atoms, R.sup.y and R.sup.z each, independently of one another, denote H, F, CH.sub.3 or CF.sub.3, Z.sup.1 denotes —O—, —CO—, —C(R.sup.yR.sup.z)— or —CF.sub.2CF.sub.2—, Z.sup.2 and Z.sup.3 each, independently of one another, denote —CO—O—, —O—CO—, —CH.sub.2O—, —OCH.sub.2—, —CF.sub.2O—, —OCF.sub.2— or —(CH.sub.2)—, where n is 2, 3 or 4, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF.sub.5 or straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, L′ and L″ each, independently of one another, denote H, F or Cl, r denotes 0, 1, 2, 3 or 4, s denotes 0, 1, 2 or 3, t denotes 0, 1 or 2, and x denotes 0 or 1.

12. The LC medium according to claim 1, comprising <5% by weight of polymerizable compounds.

13. 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, and 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.

14. The LC display according to claim 13, wherein the substrates have no alignment layers for homeotropic alignment.

15. The LC display according to claim 13, wherein the substrates have unrubbed alignment layers on one or both sides.

16. The LC display according to claim 13, which is a VA display containing an LC medium having negative dielectric anisotropy and electrodes arranged on opposite substrates.

17. The LC display according to claim 13, which is a VA-IPS display containing an LC medium having positive dielectric anisotropy and two electrodes arranged on at least one substrate.

18. A process for preparing a LC medium according to claim 1, comprising mixing together one or more compounds of formula I with a low-molecular-weight liquid-crystalline component or components, and optionally adding one or more polymerizable compounds and/or auxiliary substances.

19. A compound of formula I′
R.sup.1-A.sup.1-(Z.sup.2-A.sup.2).sub.m1-R.sup.2  (I′) in which R.sup.2 denotes ##STR00271## n independently denotes 1, 2, 3 or 4, Sp.sup.1, Sp.sup.3, Sp.sup.5 independently of each other, denotes a spacer group or a single bond, Sp.sup.2 denotes a trivalent, acyclic spacer group, Sp.sup.4 denotes a tetravalent, acyclic spacer group, Y is independently of each other O, S, (CO), NR.sup.0 or a single bond, X.sup.1 and X.sup.2 independently of each other a group —OH, —NH.sub.2, —NHR.sup.11, —SH, —SR.sup.11, —NR.sup.11.sub.2, —OR.sup.11 or —(CO)OH, ##STR00272## R.sup.11 in each case independently denotes a halogenated or unsubstituted alkyl chain having 1 to 15 C atoms, in which one or more CH.sub.2 groups are each optionally replaced, independently of one another, by —C≡C—, —CH═CH—, —(CO)O—, —O(CO)—, —(CO)— or —O— in such a way that O or N atoms are not linked directly to one another, and where two radicals R.sup.11 are optionally linked to one another to form a ring, B a ring or condensed ring, optionally substituted by one, two or three R.sup.L, p is 2, 3, 4 or 5, A.sup.1 and A.sup.2 each, independently of one another, denote an aromatic, heteroaromatic, alicyclic or heterocyclic group, which optionally contains fused rings, and which is optionally mono- or polysubstituted by R.sup.L, R.sup.L in each case, independently of one another, denotes OH, SH, SR.sup.0, —(CH.sub.2).sub.n1—OH, 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, —N(R.sup.0).sub.2, —(CH.sub.2).sub.n1—N(R.sup.0).sub.2, optionally substituted silyl, optionally substituted aryl or cycloalkyl having 6 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, in which one or more H atoms are optionally replaced by F or Cl, and two vicinal R.sup.L together are optionally ═O, n1 denotes 1, 2, 3, 4 or 5, Z.sup.2 in each case, independently of one another, denotes a single bond, —O—, —S—, —CO—, —CO—O—, —OCO—, —O—CO—O—, —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—, —CH═CH—, —CF═CF—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH— or CR.sup.0R.sup.00, R.sup.0 and R.sup.00 each, independently of one another, denote 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 one or more non-adjacent CH.sub.2 groups are optionally replaced by —C≡C—, —CH═CH, —NR.sup.0—, —O—, —S—, —CO—, —CO—O—, —O—CO—, or —O—CO—O— in such a way that N, O and/or S atoms are not linked directly to one another, and in which one or more tertiary carbon atoms (CH groups) are optionally replaced by N, and in which one or more H atoms are optionally replaced by F or Cl, and m1 denotes 1, 2, 3 or 4.

20. The compound according to claim 19, wherein Sp.sup.1 is not a single bond.

21. The compound according to claim 19, wherein m1 denotes 1, 2 or 3, and R.sup.2 denotes a group of formula ##STR00273## and p, Sp.sup.1, ring B, Y, Sp.sup.3 and X.sup.2 are defined as for the compound of formula I′.

22. A method for effecting homeotropic alignment between two substrates of an LC cell, comprising providing a layer of the LC medium according to claim 1 between the two substrates.

23. A process for preparing a LC display comprising a 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, comprising the process steps of: filling of the cell with the LC medium according to claim 1 and optionally a polymerizable component, and optionally polymerizing the polymerizable component, optionally with application of a voltage to the cell or under the action of an electric field.

24. A compound of formula I′
R.sup.1-A.sup.1-(Z.sup.2-A.sup.2).sub.m1-R.sup.2  (I′) in which R.sup.2 denotes a group ##STR00274## Sp.sup.1, Sp.sup.3, Sp.sup.5 independently of each other, denotes a spacer group or a single bond, Sp.sup.2 denotes a trivalent, acyclic spacer group, Sp.sup.4 denotes a tetravalent, acyclic spacer group, Y is independently of each other O, S, (CO), NR.sup.0 or a single bond, X.sup.1 and X.sup.2 independently of each other a group —OH, —NH.sub.2, —NHR.sup.11, —SH, —SR.sup.11, —NR.sup.11.sub.2, —OR.sup.11 or —(CO)OH, ##STR00275## R.sup.11 in each case independently denotes a halogenated or unsubstituted alkyl chain having 1 to 15 C atoms, in which one or more CH.sub.2 groups are each optionally replaced, independently of one another, by —C≡C—, —CH═CH—, —(CO)O—, —O(CO)—, —(CO)— or —O— in such a way that O or N atoms are not linked directly to one another, and where two radicals R.sup.11 are optionally linked to one another to form a ring, B a ring or condensed ring, optionally substituted by one, two or three R.sup.L, p is 2, 3, 4 or 5, A.sup.1 and A.sup.2 each, independently of one another, denote 1,4-phenylene and/or cyclohexane-1,4-diyl, which is optionally mono- or polysubstituted by R.sup.L, R.sup.L in each case, independently of one another, denotes OH, SH, SR.sup.0, —(CH.sub.2).sub.n1—OH, 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, —N(R.sup.0).sub.2, —(CH.sub.2).sub.n1—N(R.sup.0).sub.2, optionally substituted silyl, optionally substituted aryl or cycloalkyl having 6 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, in which one or more H atoms are optionally replaced by F or Cl, and two vicinal R.sup.L together are optionally ═O, n1 denotes 1, 2, 3, 4 or 5, Z.sup.2 in each case, independently of one another, denotes a single bond, —O—, —S—, —CO—, —CO—O—, —OCO—, —O—CO—O—, —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—, —CH═CH—, —CF═CF—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH— or CR.sup.0R.sup.00, R.sup.0 and R.sup.00 each, independently of one another, denote 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 one or more non-adjacent CH.sub.2 groups are optionally replaced by —C≡C—, —CH═CH—, —NR.sup.0—, —O—, —S—, —CO—, —CO—O—, —O—CO—, or —O—CO—O— in such a way that N, O and/or S atoms are not linked directly to one another, and in which one or more tertiary carbon atoms (CH groups) are optionally replaced by N, and in which one or more H atoms are optionally replaced by F or Cl, and m1 denotes 2, 3 or 4.

Description

EXAMPLES

(1) The compounds employed, if not commercially available, are synthesised by standard laboratory procedures. The LC media originate from Merck KGaA, Germany.

COMPOUNDS—SYNTHESIS EXAMPLES

Example 1. 2-(trans-4-Propyl-cyclohexyl)-propane-1,3-diol

(2) (CAS-No. 132310-86-2), is commercially available.

(3) ##STR00178##

Example 2. 2-(trans-trans-4′-Propyl-bicyclohexyl-4-yl)-propane-1,3-diol

(4) (CAS-No. 188660-24-4), is prepared as described in DE 19531135 A1.

(5) ##STR00179##

Example 3. 2-[4-(2-Hydroxy-ethyl)-4′-propyl-bicyclohexyl-4-yl]-ethanol

(6) (1315986-27-6) is prepared as described in WO 2011/088882 A1.

(7) ##STR00180##

Example 4. 2-[5-(2-Hydroxy-ethoxy)-4′-pentyl-biphenyl-3-yloxy]-ethanol

4.1 3,5-dimethoxy-4′-pentylbiphenyl

(8) ##STR00181##

(9) 45.4 g (0.326 mol) sodium metaborate tetrahydrate and 8.25 g (12 mmol) bis(triphenylphosphine)palladium(II)chloride) are dissolved in water (150 ml). After addition of hydrazine hydrate (1 ml) a solution of 40.0 g (0.206 mol) 4-pentylbenzene boronic acid and 69.1 g (0.227 mol) 3,5-dimethoxyphenyl triflate in THF (900 ml) is added and the reaction is refluxed overnight and cooled to room temperature. Ethyl acetate is added, the aq. layer extracted with ethyl acetate and the combined organic layers are dried over sodium sulfate. The solvent is evaporated and the residue purified by chromatography on silica (heptane/toluene 1:1, then 1:9). 3,5-dimethoxy-4′-pentylbiphenyl is obtained as colourless crystals.

(10) .sup.1H NMR (500 MHz, CDCl.sub.3)

(11) δ=0.90 ppm (t, J=6.9 Hz, 3H, CH.sub.3), 1.28-1.41 (m, 4H, CH.sub.2), 1.59-1.70 (2H, CH.sub.2), 2.63 (t, J=7.5 Hz, 2H, Ar—CH.sub.2—CH.sub.2—), 3.83 (s, 6H, 2-OCH.sub.3), 6.44 (t, J=2.3 Hz, 1H, Ar—H), 6.72 (d, J=2.2 Hz, 2H, Ar—H), 7.23 (d, J=8.1 Hz, 2H, Ar—H), 7.48 (d, J=8.1 Hz, 2H, Ar—H).

4.2 4′-Pentylbiphenyl-3,5-diol

(12) ##STR00182##

(13) 5.00 g (17.4 mmol) 3,5-dimethoxy-4′-pentylbiphenyl are dissolved in dichloromethane (70 ml) and a solution of 4 ml (43 mmol) of boron tribromide in dichloromethane (10 ml) is added dropwise under ice-cooling. The reaction is stirred for 3 h at the same temperature, is poured onto ice and the aq. layer is extracted three times with ethyl acetate. The combined org. layers are evaporated and the residue is recrystallised from toluene/heptane (1:2) to yield 4′-pentylbiphenyl-3,5-diol as colourless crystals.

(14) .sup.1H NMR (400 MHz, DMSO-d.sub.6)

(15) δ=0.87 ppm (t, J=6.8 Hz, 3H, CH.sub.3), 1.23-1.38 (m, 4H, CH.sub.2), 1.53-1.64 (2H, CH.sub.2), 2.58 (t, J=7.5 Hz, 2H, Ar—CH.sub.2—CH.sub.2—), 6.19 (t, J=2.3 Hz, 1H, Ar—H), 6.43 (d, J=2.2 Hz, 2H, Ar—H), 7.23 (d, J=8.2 Hz, 2H, Ar—H), 7.42 (d, J=8.1 Hz, 2H, Ar—H), 9.25 (s, 2H, —OH).

4.3 (5-Ethoxycarbonylmethoxy-4′-pentyl-biphenyl-3-yloxy)-acetic acid ethyl ester

(16) ##STR00183##

(17) To 28.0 g (109 mmol) 4′-Pentylbiphenyl-3,5-diol and 107 g (328 mmol) caesium carbonate in 300 ml ethyl methyl ketone, 54.7 g (328 mmol) ethyl bromoacetate are added at 50° C. The reaction is heated under reflux for 4 h, cooled and diluted with 200 ml ethyl acetate. After addition of 200 ml water, the mixture is acidified carefully with 2 M hydrochloric acid. The aq. phase is separated and extracted three times with ethyl acetate. The combined org. layers are washed with brine, dried over sodium sulfate and the solvent is evaporated. The residue is filtered through silica with toluene/ethyl acetate (92:8) and the product is used in the next step without further purification.

4.4 2-[5-(2-Hydroxy-ethoxy)-4′-pentyl-biphenyl-3-yloxy]-ethanol

(18) ##STR00184##

(19) 37.4 g (86.8 mmol) (5-Ethoxycarbonylmethoxy-4′-pentyl-biphenyl-3-yloxy)-acetic acid ethyl ester are dissolved in 200 ml THF and under cooling with ice, 86.8 ml (172 mmol) of a 2 M solution of lithium aluminium hydride in THF is added so that the temperature did not exceed 30° C. After 3 h the reaction is poured onto ice-water, acidified with 2 M hydrochloric acid and extracted three times with ethyl acetate. The combined org. layers are dried over solium sulfate and the solvent is evaporated. The residue is filtered through silica with ethyl acetate/toluene (2:1) and recrystallised from toluene ethyl acetate (8:2) to give 2-[5-(2-Hydroxy-ethoxy)-4′-pentyl-biphenyl-3-yloxy]-ethanol as colourless crystals, m.p. 94° C.

Example 5. 3-[5-(3-Hydroxy-propoxy)-4′-pentyl-biphenyl-3-yloxy]-propan-1-ol

(20) ##STR00185##

(21) 2.70 g (10.5 mmol) 4′-pentylbiphenyl-3,5-diol, 5.86 g (42.1 mmol) 3-bromo-1-propanol and 6.11 g (44.1 mmol) potassium carbonate are heated in 60 ml ethyl methyl ketone overnight. The reaction is filtered, evaporated and the crude product is purified by chromatography on silica (ethyl acetate/toluene (7:3)) and recrystallised from heptane/ethyl acetate (9:1) to give 3-[5-(3-Hydroxy-propoxy)-4′-pentyl-biphenyl-3-yloxy]-propan-1-ol as colourless crystals, m.p. 90° C.

Example 6. 2-[2-(2-Fluoro-4′-propyl-biphenyl-4-yl)-ethyl]-propane-1,3-diol

6.1 2-[2-(2-Fluoro-4′-propyl-biphenyl-4-yl)-ethyl]-malonic acid diethyl ester

(22) ##STR00186##

(23) 24 ml (0.063 mol) of a 20% solution of sodium ethanoate in ethanol is diluted with 10 ml of ethanol, and 9.5 ml (0.062 mol) ethyl malonate followed by 10.0 g (0.031 mol) 4-(2-Bromo-ethyl)-2-fluoro-4′-propyl-biphenyl are added under reflux. The reaction is refluxed for 2 h, water is added and the solution is extracted three times with MTB-Ether. The combined org. layers are washed with brine and dried over sodium sulfate. The solvent is evaporated and the product is purified by column chromatography with heptane/ethyl acetate (9:1) on silica and excess ethyl malonate is removed by bulb-to-bulb distillation. 2-[2-(2-Fluoro-4-propyl-biphenyl-4-yl)-ethyl]-malonic acid diethyl ester is obtained as yellow oil.

(24) .sup.1H NMR (500 MHz, CDCl.sub.3)

(25) δ=0.98 ppm (t, J=7.3 Hz, 3H, CH.sub.3), 1.28 (t, J=7.1 Hz, 6H, —OCH.sub.2CH.sub.3), 1.68 (sext., J=7.4 Hz, 2H, CH.sub.2), 2.25 (q, J=7.7 Hz, 2H, CH.sub.2), 2.63 (dd, J=7.5 Hz, J=7.7 Hz, 2H, CH.sub.2), 2.69 (dd, J=7.4 Hz, J=8.1 Hz, 2H, CH.sub.2), 3.36 (s, 1H, —CH(COOEt).sub.2), 4.21 (q, J=7.1 Hz, 4H, —OCH.sub.2CH.sub.3), 6.98 (dd, J=11.6 Hz, J=1.5 Hz, 1H, Ar—H), 7.02 (dd, J=7.8 Hz, J=1.6 Hz, 1H, Ar—H), 7.24 (d, J=8.2 Hz, 2H, Ar—H), 7.34 (t, J=8.0 Hz, 1H, Ar—H), 7.45 (d, J=8.2 Hz, J=1.5 Hz, 2H, Ar—H).

6.2 2-[2-(2-Fluoro-4′-propyl-biphenyl-4-yl)-ethyl]-propane-1,3-diol

(26) ##STR00187##

(27) 550 mg (14.5 mmol) lithiumaluminiumhydride are suspended in 4 ml toluene and a solution of 4.80 g (12 mmol) 2-[2-(2-Fluoro-4′-propyl-biphenyl-4-yl)-ethyl]-malonic acid diethyl ester in 20 ml THF is added dropwise. The reaction is refluxed for 1 h, poured onto ice-water and acidified with 2 N hydrochloric acid. The aq. layer is separated and extracted three times with MTB-Ether. The combined org. layer are washed with brine, dried over sodium sulfate and the solvent is evaporated. Crystallisation from heptane gave 2-[2-(2-Fluoro-4′-propyl-biphenyl-4-yl)-ethyl]-propane-1,3-diol as a white solid, m.p. 66° C. Phases: K 66 SmC 73 I.

Example 7. 2-[2-(2-Ethyl-4′-propyl-biphenyl-4-yl)-ethyl]-propane-1,3-diol

(28) ##STR00188##

(29) Analogous to example 6, 2-[2-(2-Ethyl-4′-propyl-biphenyl-4-yl)-ethyl]-propane-1,3-diol is obtained as colourless crystals. M.p.=70° C.

Example 8. 2-[2-(4′-Propyl-biphenyl-4-yl)-ethyl]-propane-1,3-diol

(30) ##STR00189##

(31) Analogous to example 6, 2-[2-(4′-Propyl-biphenyl-4-yl)-ethyl]-propane-1,3-diol is obtained as colourless crystals.

Example 9. 5-[2-(2-Hydroxy-ethoxy)-ethoxy]-4′-pentyl-biphenyl-3-ol

(32) ##STR00190##

(33) 2.90 g (11.3 mmol) 4′-pentylbiphenyl-3,5-diol and 1.41 g (11.3 mmol) 2-(2-Chloro-ethoxy)-ethanol are dissolved in 30 ml DMF, 1.56 g (11.3 mmol) potassium carbonate are added and the reaction is heated at 100° C. for 2 d. After cooling to room temp. the solution is carefully acidified with 1 M hydrochloric acid, diluted with MTB-Ether and washed with brine. The solvent is evaporated and the crude product is purified by chromatography on silica (ethyl acetate/toluene 7:3) and crystallised from heptane/ethyl acetate at −30° C.

(34) 5-[2-(2-Hydroxy-ethoxy)-ethoxy]-4′-pentyl-biphenyl-3-ol is obtained as colourless crystals, m.p. 64° C.

Example 10 2-[2-(2′-Ethyl-4″-pentyl-[1,1′;4′,1″]terphenyl-4-yl)-ethyl]-propane-1,3-diol

10.1 Synthesis of 2-[4-(4,4,5,5-Tetramethyl[1,3,2]dioxaborolan-2-yl)-phenyl]-ethanol A

(35) ##STR00191##

(36) 20.0 g (99.5 mmol) 2-(4-Bromo-phenyl)-ethanol, 28.4 g (109.4 mmol) bis-(pinacolato)-diboron, 32.3 g (330 mmol) potassium acetate and 2.5 g (3.4 mmol) PdCl.sub.2dppf are dissolved in 355 ml 1,4-dioxane and are refluxed overnight. The reaction mixture is cooled to room temperature and 300 ml water is added. The mixture is extracted four times with Methyl-tert-butyl ether, washed with brine, dried over sodium sulphate, filtered and evaporated under vacuum. The crude product is purified via silica gel chromatography (toluene/ethyl acetate 4:1) to give 22 g (87% yield) of the product as yellow oil.

10.2 Synthesis of 2-(4′-Bromo-2′-ethyl-biphenyl-4-yl)-ethanol B

(37) ##STR00192##

(38) 25 g (236 mmol) sodium carbonate is dissolved in 175 ml water and 75 ml ethanol. 29.6 g (95.2 mmol) 4-bromo-2-ethyl-1-iodo-benzene, 23.6 g (95.0 mmol) boronic ester A are dissolved in 375 ml toluene added to the reaction mixture. After adding Pd(PPh.sub.3).sub.4 to the mixture it is refluxed for 5.5 h and cooled to room temperature. The organic phase is separated and the water phase is extracted two times with ethyl acetate. The combined organic phases are washed with brine, dried over sodium sulphate, filtered and evaporated under vacuum. The crude product is purified via silica gel chromatography (heptane/ethyl acetate 8:2) and (toluene/ethyl Acetate 95:5) to give 24.5 g (80% yield) of the product.

10.3 Synthesis of 2-(2′-Ethyl-4″-pentyl-[1,1′;4′,1″]terphenyl-4-yl)-ethanol C

(39) ##STR00193##

(40) 14.2 g (101 mmol) sodium metaborate tetrahydrate are dissolved in 215 ml water and added with 960 mg (1.34 mmol) Pd(PPh.sub.3).sub.2Cl.sub.2, 0.065 ml hydrazinium hydroxide, 21.5 g (67.0 mmol) of bromine B and 25 ml THF. The mixture is stirred for 5 min and then added with 12.9 g (67.2 mmol) 4-(pentylphenyl) boronic acid in 50 ml THF. The reaction mixture is refluxed for 16 h and cooled to room temperature. The reaction product is extracted with methyl-tert-butyl ether and the organic layer is washed with brine, dried over sodium sulphate, filtered and evaporated under vacuum. The crude product is purified via silica gel chromate-grapy (toluene/heptane 1:1) and afterwards crystallized from heptane to give 17.8 g (71% yield) of the product as white crystals.

10.4 4-(2-Bromo-ethyl)-2′-ethyl-4″-pentyl-[1,1′;4′,1″]terphenyl D

(41) ##STR00194##

(42) 17.8 g (48.0 mmol) of alcohol C is solved in 93.0 ml (0.81 mol) of hydrobromic acid. The reaction mixture is refluxed for 16 h and cooled to room temperature. 50 ml of water are added and the layers separated. The product layer washed with brine, filtered, evaporated under vacuum and purified via silica gel chromatography with heptane/ethyl acetate (9:1) to give 15.6 g (73% yield) of the product as an oil.

10.5 Synthesis of 2-[2-(2′-Ethyl-4″-pentyl-[1,1′;4′,1″]terphenyl-4-yl)-ethyl]-malonicacid diethyl ester E

(43) ##STR00195##

(44) To 45 ml (0.77 mol) ethanol are added 1.5 g (65 mmol) sodium metal in small portions. (caution: H.sub.2 formation) Afterwards are added 16.7 ml (109 mmol) diethylmalonate and 29.6 g (69 mmol) bromide Din 5 ml ethanol. The reaction mixture is then refluxed for 2.5 h and cooled to room temperature and evaporated. It is added with water and methyl-tert-butyl ether and ethyl acetate. The combined organic layers are washed with brine, dried with sodium hydrogen sulphate, filtered and evaporated under vacuum. The crude product is purified via silica gel chromatography (heptane/ethyl acetate 9:1) to give 15.5 g (44% yield) of the product.

10.6 2-[2-(2′-Ethyl-4″-pentyl-[1,1′;4′,1″]terphenyl-4-yl)-ethyl]-propane-1,3-diol F

(45) ##STR00196##

(46) 0.66 g (17.4 mmol) LiAlH.sub.4 powder is added to 3.6 ml toluene. Afterwards 15 ml THF are cautiously added and, at 0 to 10° C., 7.5 g (0.14 mmol) of malonic ester E dissolved in 30 ml THF are slowly added. After complete addition the reaction mixture is stirred at 65° C. for 3.5 h, then cooled to 5° C. and very cautiously quenched with a 10 ml THF-water (1:1) mixture (H.sub.2 generation!). The white suspension is treated with 2 N HCl until a pH value of 1 is reached. 50 ml of water are added and the mixture is extracted with 100 ml of ethyl ether. The organic layer is separated, washed with water, brine and dried over sodium sulphate. It is filtered and evaporated under vacuum. The crude product is purified via silica gel chromatography with heptane and heptane/ethyl acetate (8:2). The obtained product is finally crystallized from heptane and the product is obtained as white crystals with 3.5 g (58% yield).

(47) Phases: Tg−25 K 79 SmA 96 I

(48) .sup.1H NMR (500 MHz, DMSO-d.sub.6):

(49) δ=0.88 ppm (t, 7.02 Hz, 3H, CH.sub.3), 1.08 ppm (t, 7.54 Hz, 3H, CH.sub.3), 1.32 ppm (m.sub.c, 4H, CH.sub.2—H), 1.6 ppm (m, 5H, CH.sub.2—H, CH(CH.sub.2OH).sub.2), 2.64 ppm (m, 6H, arom.-CH.sub.2), 3.45 ppm (m.sub.c, 4H, CH.sub.2OH), 4.34 ppm (t, 5.2 Hz, 2H, OH), 7.25 ppm (m, 7H, arom.-H), 7.48 ppm (dd, 7.92 Hz, 1.97 Hz, 1H, arom.-H), 7.57 ppm (d, 1.92 Hz, 1H, arom.-H), 7.60 ppm (d, 8.2 Hz, 2H, arom.-H).

Example 11. 2-[2-(4′-Propyl-bicyclohexyl-4-yl)-ethoxy]-propane-1,3-diol

11.1 4′-[2-(2-Benzyloxy-1-benzyloxymethyl-ethoxy)-ethyl]-4-propyl-bicyclohexyl

(50) ##STR00197##

(51) 9.9 g (35 mmol) 1,3-dibenzyloxypropan-2-ol are dissolved in 20 ml DMF and added dropwise at 0° C. to a suspension of 1.8 g (44 mmol) sodium hydride (60% in paraffin oil) in 30 ml of DMF. After the effervescence had ceased, the cooling bath is removed and a solution of 9.3 g (29 mmol) 4′-(2-bromo-ethyl)-4-propyl-bicyclohexyl in 50 ml DMF is added. The reaction is stirred overnight, poured onto ice water, acidified with 2 M hydrochloric acid and extracted tree times with MTB-Ether. The combined org. layers are washed with brine, dried over sodium sulfate and evaporated. The crude 4′-[2-(2-benzyloxy-1-benzyloxymethyl-ethoxy)-ethyl]-4-propyl-bicyclohexyl is obtained as colourless oil which is used in the next step without further purification.

(52) .sup.1H NMR (500 MHz, CDCl.sub.3)

(53) δ=0.78-1.18 ppm (m, 17H, aliphatic H, therein: 0.87 (t, J=7.4 Hz, CH.sub.3), 1.22-1.35 (m, 3H, aliphatic H), 1.47 (q, J=6.9 Hz, 1H, aliphatic H), 1.65-1.81 (m, 8H, aliphatic-H), 3.53-3.69 (m, 6H, —CH.sub.2O—), 4.06 (tt, J=4.5 Hz, J=6.2 Hz, 1H, —OCH(CH.sub.2O—).sub.2—), 4.59 (s, 4H, PhCH2O—), 7.38-7.42 (m, 10H, Ar—H).

11.2 2-[2-(4′-Propyl-bicyclohexyl-4-yl)-ethoxy]-propane-1,3-diol

(54) ##STR00198##

(55) 5.00 g (9.87 mmol) 4′-[2-(2-benzyloxy-1-benzyloxymethyl-ethoxy)-ethyl]-4-propyl-bicyclohexyl in THF are hydrogenated in the presence of palladium in charcoal until the reaction ceased. The solution is filtered, evaporated and the crude product is recrystallised from ethanol to give 2-[2-(4′-propyl-bicyclohexyl-4-yl)-ethoxy]-propane-1,3-diol as colourless crystals.

Example 12. 2-(2-{2-Ethyl-2′-fluoro-4′-[2-(4-pentyl-phenyl)-ethyl]-biphenyl-4-yl}-ethyl)-propane-1,3-diol

(56) ##STR00199##

12.1 1-Bromo-2-fluoro-4-(4-pentyl-phenylethynyl)-benzene A

(57) ##STR00200##

(58) 86.0 g (0.286 mol) of 4-bromo-2-fluoro-1-iodo-benzene, 4.5 g (6.41 mmol) Pd(PPh.sub.3).sub.2Cl.sub.2 and 1.20 g (6.30 mmol) of CuI are solved at RT in 500 ml triethylamine and properly degassed. 50.0 g (0.290 mol) of 1-ethynyl-4-pentyl-benzene is solved in 100 ml triethylamine and added dropwise to the mixture. The reaction temperature rises during the addition of the alkine and the reaction mixture is stirred at room temperature for 18 h. The reaction mixture is diluted with water, extracted with methyl tert-butyl ether and dried over Na.sub.2SO.sub.4. After evaporation of the solvent the crude product is purified via column chromatography with heptane and the product is obtained as a yellow solid.

12.2 Synthesis of Boronic Acid B

(59) 139.5 g (0.404 mol) of product A are dissolved in 1000 ml THF and cooled to −78° C. and 260 ml (1.6 M in hexane, 0.42 mol) of n-butyllithium are added dropwise at this temperature. After stirring for 15 min at −78° C. 50.0 ml (0.44 mol) of trimethyl borate is added dropwise and the resulting reaction mixture is stirred over night (18 h) with temperature rising up to room temperature during this time. The reaction mixture is acidified at 0° C. with 2 N HCl and the organic layer is separated, dried over brine and evaporated under vacuum to give the product B as slightly yellow crystals.

(60) .sup.1H NMR (500 MHz, CDCl.sub.3): δ=0.93 ppm (t, 6.9 Hz, 3H, CH.sub.3), 1.36 ppm (m.sub.c, 4H, CH.sub.2—H), 1.65 ppm (quint., 7.5 Hz, 2H, CH.sub.2), 2.65 ppm (t, 7.8 Hz, 2H, CH.sub.2), 7.20 ppm (d, 8.2 Hz, 3H, Ar.—H), 7.29 ppm (dd, 8.2 Hz, 1.8 Hz, 1H, Ar—H), 7.46 ppm (d, 8.2 Hz, 2H, Ar—H), 7.53 ppm (dd, 8.3 Hz, 8.2 Hz, 1H, Ar.—H).

12.3 Synthesis of 4′-Bromo-2′-ethyl-2-fluoro-4-(4-pentyl-phenylethynyl)-biphenyl C

(61) ##STR00201##

(62) 28.2 g (0.266 mol) Na.sub.2CO.sub.3 is dissolved in 100 ml water and to this 207 ml toluene and 33.2 g (106.9 mmol) of 4-bromo-2-ethyl-1-iodo-benzene are added. The mixture is heated to 75° C., 3.8 g (3.3 mmol) Pd(PPh.sub.3).sub.4 are added and immediately a solution of boronic acid B (33.4 g [0.107 mol] in 33.2 ml ethanol is added during 15 min. The reaction mixture is refluxed for 18 h and is diluted with toluene and washed with water. The organic layer is washed with brine, dried over Na.sub.2SO.sub.4 and evaporated under vacuum. Raw material C is purified with heptane and heptane/toluene (10:1) via column chromatography and the product is obtained as a white solid.

12.4 Synthesis of 2-[2-Ethyl-2′-fluoro-4′-(4-pentyl-phenylethynyl)-biphenyl-4-yl]-ethano D

(63) ##STR00202##

(64) 35.9 g (77.0 mmol) of bromide C is solved in 100 ml THF and cooled to −78° C. and n-butyl-lithium (51 ml, 1.6 M, [82.0 mmol]) is added dropwise. To the reaction mixture is added 4.1 g (93.0 mmol) of ethylene oxide in 10 ml cooled (0° C.) THF and after 30 min stirring at −78° C. 10.1 ml (80.0 mmol) of boron trifluoride etherate in 40 ml THF is added cautiously dropwise (exothermic reaction). The reaction mixture is allowed to rise to room temperature during 5 h and is then poured into ice water and extracted with methyl-tert-butyl ether. The combined organic layers are washed with brine and dried over Na.sub.2SO.sub.4 and evaporated under vacuum. The crude product is filtered via column chromatography and the product is obtained as a solid material.

12.5 Synthesis of 2-{2-Ethyl-2′-fluoro-4′-[2-(4-pentyl-phenyl)-ethyl]-biphenyl-4-yl}-ethanol

(65) ##STR00203##

(66) 21.8 g (51.0 mmol) of alkine D is dissolved in 200 ml THF and to this 4.40 g Pd—C (5%/E101R/54% H.sub.2O, Degussa) is added. The triple bond is reduced with H.sub.2 (3.0 PRAX Air GmbH) at normal pressure and RT within 32 h after an additional addition of 4.4 g Pd—C after 16 h. The reaction mixture is filtered with silica gel with toluene/methyl tert-butyl ether (9:1) and evaporated under vacuum to give alcohol E.

12.6 Synthesis of methanesulfonic acid 2-{2-ethyl-2′-fluoro-4′-[2-(4-pentyl-phenyl)-ethyl]-biphenyl-4-yl}-ethyl ester F

(67) ##STR00204##

(68) 21.8 g (52.0 mmol) of alcohol E and 600 mg (4.91 mmol) 4-dimethylaminopyridine is solved in 100 ml dichloromethane and 9.5 ml (117.7 mmol) pyridine is added. The reaction mixture is cooled to 0° C. and 4.80 ml (62.0 mmol) methanesulfonylchloride is added. The mixture is stirred for 18 h and the temperature is allowed to rise up to room temperature during that time. After complete conversion the mixture is diluted with water and extracted with dichloromethane. The organic layer is washed with 2 N HCl and water, dried with Na.sub.2SO.sub.4 and evaporated under vacuum. The crude product is filtered over silica gel with dichloromethane and the product is obtained as a colourless oil.

12.7 2-(2-{2-Ethyl-2′-fluoro-4′-[2-(4-pentyl-phenyl)-ethyl]-biphenyl-4-yl}-ethyl)-propane-1,3-diol (Example 12)

(69) ##STR00205##

(70) The synthetic transformations starting from F via G are done under the same reaction conditions like shown in the synthesis examples 10.5 and 10.6.

(71) The title product is obtained as a colourless oil which, after extended cooling at −20° C., crystallizes to a white solid (mp.=35° C.).

(72) Phases: Tg−34 Sm 21 K [35] I

(73) .sup.1H NMR (500 MHz, CDCl.sub.3): δ=0.89 ppm (t, 7.0 Hz, 3H, CH.sub.3), 1.07 ppm (t, 7.6 Hz, 3H, CH.sub.3), 1.32 ppm (m.sub.c, 4H, CH.sub.2—H), 1.64 ppm (m, 4H), 1.86 ppm (m.sub.c, 1H, CH(CH.sub.2OH).sub.2, 2.19 ppm (t, 4.9 Hz, 2H, OH), 2.49 ppm (q, 7.5 Hz, 2H, CH.sub.2), 2.58 ppm (dd, 7.9 Hz, 2H, CH.sub.2), 2.70 ppm (dd, 8.0 Hz, 2H, CH.sub.2), 2.94 (s, 4H, CH.sub.2), 3.74 ppm (m.sub.c, 2H, CH.sub.2OH), 3.89 ppm (m.sub.c, 2H, CH.sub.2OH), 6.94 ppm (dd, 10.6 Hz, 1.5 Hz, 1H, Arom.-H), 6.99 ppm (dd, 7.74 Hz, 1.6 Hz, 1H, Arom.-H), 7.11 ppm (m, 8H, Arom.-H).

(74) The following compounds for use in LC media are prepared analogously or in accordance with a literature procedure.

(75) According to Examples 4 and 5 the following compounds are synthesised:

(76) ##STR00206## ##STR00207## ##STR00208##

(77) According to Example 6 or 11 the following compounds are synthesized:

(78) ##STR00209## ##STR00210## ##STR00211##

(79) From the above alcohols, amines are prepared.

(80) ##STR00212##

(81) According to the example 12 the following molecules are synthesized:

(82) ##STR00213##

Mixture Examples

(83) For the preparation of the LC media according to the invention, the following liquid-crystalline mixtures consisting of low-molecular-weight components in the stated percentage proportions by weight are used.

(84) TABLE-US-00004 TABLE 1 Nematic LC medium M1 (Δε < 0) CY-3-O2 15.5% Cl.p. +75° C. CCY-3-O3   8% Δn 0.098 CCY-4-O2 .sup. 10% Δε −3.0 CPY-2-O2  5.5% ε.sub.∥ 3.4 CPY-3-O2 11.5% K.sub.3/K.sub.1 1.02 CCH-34 9.25% CCH-23 24.5% PYP-2-3 8.75% PCH-301   7%

(85) TABLE-US-00005 TABLE 2 Nematic LC medium M2 (Δε < 0) CY-3-O4 14%  Cl.p. +80° C. CCY-3-O2 9% Δn 0.090 CCY-3-O3 9% Δε −3.3 CPY-2-O2 10%  ε.sub.∥ 3.4 CPY-3-O2 10%  K.sub.3/K.sub.1 0.97 CCY-3-1 8% CCH-34 9% CCH-35 6% PCH-53 10%  CCH-301 6% CCH-303 9%

(86) TABLE-US-00006 TABLE 3 Nematic LC medium M3 (Δε < 0) CC-4-V 10% Cl.p. +77° C. CC-5-V 13.5%.sup.  Δn 0.113 PGU-3-F 6.5%  Δε 19.2 ACQU-2-F 10% ε.sub.∥ 23.8 ACQU-3-F 12% K.sub.3/K.sub.1 0.97 PUQU-3-F 11% CCP-V-1 12% APUQU-2-F  6% APUQU-3-F  7% PGUQU-3-F  8% CPGU-3-OT  4%

(87) The following compounds 1 to 40 are used as self-aligning additives:

(88) TABLE-US-00007 Compound No. Structure  1  2  3  4  5  6  7 0  8  9 10 11 12 13 14 15 16 17 0 18 19 20 21 22 23 24 25 26 27 0 28 29 30 31 32 33 34 35 36 37 0 38 39 40

(89) The following polymerizable mesogens are employed:

(90) ##STR00254##

Mixture Example 1

(91) The compound no. 1 (0.5% by weight) is added to the nematic LC medium M1 of the VA type (Δ∈<0, Table 1) and the mixture is homogenised.

(92) Use in Test Cells without Pre-Alignment Layer:

(93) The resulting mixture is introduced into a test cell (without polyimide alignment layer, LC layer thickness d≈4.0 μm, ITO coating on both sides (structured ITO in case of a multi-domain switching), no passivation layer). The LC medium has spontaneous homeotropic (vertical) alignment to the substrate surfaces. In the temperature-stable range, the VA cell can be switched reversibly between crossed polarisers by application of a voltage of between 0 and 30 V.

Mixture Example 2

(94) The compound 1 (0.5% by weight) is added to a nematic LC medium M3 of the VA-IPS type (Δ∈>0, Table 3) and the mixture is homogenised.

(95) Use in Test Cells without Pre-Alignment Layer:

(96) The resulting mixture is introduced into a test cell (without polyimide alignment layer, layer thickness d≈4 μm, ITO interdigital electrodes arranged on a substrate surface, glass on the opposite substrate surface, no passivation layer). The LC medium has spontaneous homeotropic (vertical) alignment to the substrate surfaces. In the temperature-stable range, the VA-IPS cell can be switched reversibly between crossed polarisers by application of a voltage of between 0 and 20 V.

Mixture Examples 3-41

(97) The compounds 2 to 40 are added analogously to Mixture Example 1 to a nematic LC medium M1 (Δ∈<0) and the mixture is homogenised. The proportions by weight of the compounds in the medium are indicated in Table 4. The resulting LC medium is in each case introduced into a test cell as in Mixture Example 1 (without pre-alignment layer) and shows spontaneous homeotropic (vertical) alignment to the substrate surfaces. In the temperature-stable range, the VA cell can be switched reversibly between crossed polarisers by application of a voltage of between 0 and 30 V.

(98) TABLE-US-00008 TABLE 4 Proportions by weight for self-aligning additive in M1 and alignment of the resulting cell at 20° C. Test cell of the VA type. Mixture Example Compound Proportion Alignment at 20° C./ No. No. by weight switchable 3 2 0.25% homeotropic/yes 4 3 0.25% homeotropic/yes 5 4 0.25% homeotropic/yes 6 5 0.25% homeotropic/yes 7 6 0.25% homeotropic/yes 8 7 0.25% homeotropic/yes 9 8 0.25% homeotropic/yes 10 9 0.25% homeotropic/yes 11 10 0.25% homeotropic/yes 12 11 0.4% homeotropic/yes 13 12 0.4% homeotropic/yes 14 13 0.4% homeotropic/yes 15 14 0.4% homeotropic/yes 16 15 0.35% homeotropic/yes 17 16 0.1% homeotropic/yes 18 17 0.3% homeotropic/yes 19 18 0.15% homeotropic/yes 20 19 0.15% homeotropic/yes 21 20 0.15% homeotropic/yes 22 21 0.15% homeotropic/yes 23 22 0.15% homeotropic/yes 24 23 0.15% homeotropic/yes 25 24 0.15% homeotropic/yes 26 25 0.15% homeotropic/yes 27 26 0.15% homeotropic/yes 28 27 0.2% homeotropic/yes 29 28 0.2% homeotropic/yes 30 29 0.2% homeotropic/yes 31 30 0.2% homeotropic/yes 32 31 0.2% homeotropic/yes 33 32 0.2% homeotropic/yes 34 33 0.2% homeotropic/yes 35 34 0.2% homeotropic/yes 36 35 0.2% homeotropic/yes 37 36 0.2% homeotropic/yes 38 37 0.2% homeotropic/yes 39 38 0.3% homeotropic/yes 40 39 0.2% homeotropic/yes 41 40 0.15% homeotropic/yes
Results for Medium M2:

(99) According to Mixture Example 1, further mixtures with compounds 1 to 40 are prepared with the LC medium M2, employing the same proportions by weight as reported in Table 4. Each resulting LC medium is introduced into a test cell according to Mixture Example 1 without pre-alignment layer. It has spontaneous homeotropic (vertical) alignment to the substrate surfaces. In the temperature-stable range, the VA cell can be switched reversibly between crossed polarisers by application of a voltage of between 0 and 30 V.

(100) The additives no. 1 to 40 show favourable alignment properties in both LC media with negative Δ∈, M1 and M2.

Mixture Examples 42-80

(101) The compounds 2 to 40 are added analogously to Mixture Example 2 to a nematic LC medium M3 (Δ∈>0) and the mixture is homogenised. The proportions by weight of the compounds in the medium are indicated in Table 5. The resulting LC medium is in all cases introduced into a test cell without pre-alignment layer and has spontaneous homeotropic (vertical) alignment to the substrate surfaces. In the temperature-stable range, the VA-IPS cell can be switched reversibly between crossed polarisers by application of a voltage of between 0 and 20 V.

(102) TABLE-US-00009 TABLE 5 Proportions by weight for doping in M3 and alignment of the resulting cell at 20° C. Test cell of the VA-IPS type Mixture Example Compound Proportion Alignment at 20° C./ No. No. by weight switchable 42 2 0.25% homeotropic/yes 43 3 0.25% homeotropic/yes 44 4 0.25% homeotropic/yes 45 5 0.25% homeotropic/yes 46 6 0.25% homeotropic/yes 47 7 0.25% homeotropic/yes 48 8 0.25% homeotropic/yes 49 9 0.25% homeotropic/yes 50 10 0.25% homeotropic/yes 51 11 0.4% homeotropic/yes 52 12 0.4% homeotropic/yes 53 13 0.4% homeotropic/yes 54 14 0.4% homeotropic/yes 55 15 0.35% homeotropic/yes 56 16 0.1% homeotropic/yes 57 17 0.3% homeotropic/yes 58 18 0.15% homeotropic/yes 59 19 0.15% homeotropic/yes 60 20 0.15% homeotropic/yes 61 21 0.15% homeotropic/yes 62 22 0.15% homeotropic/yes 63 23 0.15% homeotropic/yes 64 24 0.15% homeotropic/yes 65 25 0.15% homeotropic/yes 66 26 0.15% homeotropic/yes 67 27 0.2% homeotropic/yes 68 28 0.2% homeotropic/yes 69 29 0.2% homeotropic/yes 70 30 0.2% homeotropic/yes 71 31 0.2% homeotropic/yes 72 32 0.2% homeotropic/yes 73 33 0.2% homeotropic/yes 74 34 0.2% homeotropic/yes 75 35 0.2% homeotropic/yes 76 36 0.2% homeotropic/yes 77 37 0.2% homeotropic/yes 78 38 0.3% homeotropic/yes 79 39 0.2% homeotropic/yes 80 40 0.15% homeotropic/yes

Mixture Example 81 to 88 (Polymer Stabilisation of Previous Mixture Examples)

(103) A polymerizable compound (RM-1, 0.3% by weight) and a self-aligning compound (5, 0.25% by weight, or 6, 0.25% by weight, or 19, 0.15% by weight, or 21, 0.15% by weight, or 26, 0.15% by weight, or 34, 0.20% by weight or 35, 0.20% by weight) are added to the nematic LC medium M1 (Δ∈<0) and the mixture is homogenised.

(104) Use in Test Cells without Pre-Alignment Layer:

(105) The resulting mixture is introduced into a test cell (without polyimide alignment layer, layer thickness d≈4.0 μm, ITO coating on both sides (structured ITO in case of a multi-domain switching), no passivation layer). The LC medium has spontaneous homeotropic (vertical) alignment to the substrate surfaces. The cell is irradiated with UV light of intensity 100 mW/cm.sup.2 at 20° C. for 15 min with application of a voltage greater than the optical threshold voltage. This causes polymerization of the monomeric, polymerizable compound. The homeotropic alignment is additionally stabilized, and the pre-tilt is tuned. The resultant PSA-VA cell can be switched reversibly at up to the clearing point with application of a voltage of between 0 and 30 V. The response times are reduced compared to the un-polymerized cell.

(106) Auxiliary substances like Irganox® 1076 (Ciba Specialty Chem.) may be added (e.g. 0.001%) for preventing spontaneous polymerization. A UV-cut filter may be used during polymerization for preventing damage of the mixtures (e.g. 320 or 340 nm UV cut-filter).

(107) Polymerization may also be performed without an applied voltage. After polymerization a passivation layer is formed, without changing the pre-tilt. The passivation layer improves the long-time stability of the self-orientation.

(108) Polymer Stabilisation of Analogous Mixture Experiments

(109) Analogously to Mixture examples 81 to 88, mixtures with RM-1 and the LC medium M2 are performed with compound 5, 6, 19, 26, 34, and 35. Comparable results to Mixture Examples 81 to 88 are obtained.

(110) Variation of the Reactive Mesogen

(111) RM-2, RM-3 and RM-4 are employed (replacing RM-1), with both M1 and M2. Comparable results to Mixture Examples 81 to 88 are obtained.

(112) Heat Load Experiments (Stability of the Self-Orientation of Mixture Examples 3 to 41)

(113) The LC media of the Mixture Examples 3 to 41 are filled into a test cell (without polyimide alignment layer, layer thickness d≈4.0 μm, ITO coating on both sides (structured ITO in case of a multi-domain switching), no passivation layer). The LC medium has spontaneous homeotropic (vertical) alignment to the substrate surfaces. The resulting VA-cell is treated at 120° C. for at least 1 h. After heat-stress, all cells still show high quality of the self-orientation. The compounds are thus compatible with the conditions of a production process used in the display industry.