CINNAMIC ACID DERIVATIVES

Abstract

The invention relates to cinnamic acid derivatives of formula S

##STR00001##

wherein the radicals have the meaning indicated in claim 1,
to a process for their preparation and their use as self assembling photoalignment agent in liquid crystal mixtures. The invention further relates to a process for the fabrication of a liquid crystal (LC) display device with homogeneous alignment by photoaligning a liquid crystal mixture with positive or negative dielectric anisotropy comprising one or more compounds of formula S and optionally a polymerisable compound, to the liquid crystal mixture comprising the self assembling photoaligning agent and optionally the polymerisable compound and to the LC display produced by said process.

Claims

1. A compound of formula S ##STR00380## wherein R.sup.1 and R.sup.12 identically or differently denote P, P-Sp-, H, F, Cl, Br, I, CN, NO.sub.2, NCO, NCS, OCN, SCN, SF.sub.5 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.00), C?C, N(R.sup.00), O, S, CO, COO, OCO, 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 be replaced by F, Cl, Br, I, CN, P or P-Sp-, P denotes a polymerisable group, Sp, Sp.sup.11, Sp.sup.12 denote a spacer group or a single bond, A.sup.11, A.sup.12 and A.sup.13 on each occurrence, identically or differently, denote an aromatic, alicyclic or heterocyclic group, and which is unsubstituted, or mono- or polysubstituted by L, Z.sup.11, Z.sup.12 on each occurrence, identically or differently, denote 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, CH?CH, CF?CF, C?C, CH?CHCOO, OCOCH?CH, CR.sup.0R.sup.00 or a single bond, R.sup.0 and R.sup.00 each, independently of one another, denote H or alkyl having 1 to 12 C atoms, n1 is 1, 2, 3 or 4, m is 0, 1 or 2, n is 0 or 1 p is 0 or 1 q is 0, 1 or 2 m+n+p+q is <4 r is 0, 1, 2 or 3, s is 0, 1, 2, 3, or 4, L P, P-Sp-, OH, CH.sub.2OH, F, Cl, Br, I, CN, NO.sub.2, NCO, NCS, OCN, SCN, C(?O)N(R.sup.x).sub.2, C(?O)Y.sup.1, C(?O)R.sup.x, N(R.sup.x).sub.2, optionally substituted silyl, optionally substituted aryl 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, in addition, one or more H atoms may be replaced by F, Cl, or P-Sp-, Y.sup.1 denotes halogen, R.sup.x denotes P, P-Sp-, 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 be replaced by O, S, CO, COO, OCO, 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 be replaced by F, Cl, P or P-Sp-, an optionally substituted aryl or aryloxy group having 6 to 40 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 40 C atoms. G denotes OH or Si(OR.sup.13).sub.3, R.sup.13 denotes straight chain or branched alkyl having 1 to 6 C atoms.

2. The compound of claim 1 selected from the following sub-formulae ##STR00381## wherein the radicals and parameters have the meaning indicated.

3. The compound of claim 1 wherein G denotes Si(OR.sup.13).sub.3.

4. The compound of claim 1 wherein G denotes OH.

5. A Liquid crystal mixture, characterised in that it comprises one or more compounds according to claim 1.

6. The liquid crystal mixture according to claim 5, characterised in that the concentration of the compounds of formula S is in the range of from 0.01 to 10% by weight.

7. The liquid crystal mixture according to claim 5, characterised in that it additionally comprises one or more polymerisable compounds of formula P
P.sup.a-(SP.sup.a).sub.s1-A.sup.2-(Z.sup.1-A.sup.1).sub.n2-(Sp.sup.b).sub.s2-P.sup.bP wherein P.sup.a P.sup.b each, independently of one another, denote a polymerisable group, Sp.sup.a, Sp.sup.b on each occurrence, identically or differently, denote a spacer group, s1, s2 each, independently of one another, denote 0 or 1, 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, wherein, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by O and/or S and wherein, in addition, one or more H atoms may be replaced by F, b) the group consisting of 1,4-phenylene and 1,3-phenylene, wherein, in addition, one or two CH groups may be replaced by N and wherein, in addition, one or more H atoms may be replaced by L, 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 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: ##STR00382## where, in addition, one or more H atoms in these radicals may be replaced by L, and/or one or more double bonds may be replaced by single bonds, and/or one or more CH groups may be replaced by N, n2 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, or (CH.sub.2).sub.n, where n is 2, 3 or 4, O, CO, C(R.sup.0R.sup.00), 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 up to 12 C atoms, 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, wherein, in addition, one or more H atoms may be replaced by F, M denotes O, S, CH.sub.2, CHY.sup.1 or CY.sup.1Y.sup.2, and Y.sup.1 and Y.sup.2 each, independently of one another, have one of the meanings indicated for R.sup.0 above or denote Cl or CN.

8. The liquid crystal mixture according to claim 5, characterised in that it comprises one or more compounds selected from the compounds of the formulae P10-1-1 and P10-1-2 ##STR00383## wherein n4 denotes an integer between 2 and 10.

9. The liquid crystal mixture according to claim 5, characterised in that it has negative dielectric anisotropy.

10. The liquid crystal mixture of claim 9, characterised in that it comprises one or more compounds selected from the following formulae: ##STR00384## wherein the individual radicals have the following meanings: a denotes 1 or 2, b denotes 0 or 1, ##STR00385## R.sup.1 and R.sup.2 each, independently of one another, denote alkyl having 1 to 12 C atoms, where, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by O, CH?CH, CO, OCO or COO in such a way that O atoms are not linked directly to one another, Z.sup.x denotes CH?CH, CH.sub.2O, OCH.sub.2, CF.sub.2O, OCF.sub.2, O, CH.sub.2, CH.sub.2CH.sub.2 or a single bond, preferably a single bond, L.sup.1-4 each, independently of one another, denote F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F, CHF.sub.2.

11. The liquid crystal mixture according to claim 5 characterised in that it has positive dielectric anisotropy.

12. The liquid crystal mixture of claim 11, characterised in that it comprises one or more compounds selected from the group of compounds of the formulae II and III, ##STR00386## wherein R.sup.20 each, identically or differently, denote a halogenated or unsubstituted alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by C?C, CF.sub.2O, CH?CH, ##STR00387## COO or OCO in such a way that O atoms are not linked directly to one another, X.sup.20 each, identically or differently, denote F, Cl, CN, SF.sub.5, SCN, NCS, a halogenated alkyl radical, a halogenated alkenyl radical, a halogenated alkoxy radical or a halogenated alkenyloxy radical, each having up to 6 C atoms, and Y.sup.20-24 each, identically or differently, denote H or F, ##STR00388## each, identically or differently, denote ##STR00389##

13. The liquid crystal mixture according to claim 11, characterised in that it comprises one or more compounds selected from the group of compounds of the formulae XI and XII ##STR00390## ##STR00391## and each, independently of one another, denote ##STR00392## and ##STR00393## denotes ##STR00394## R.sup.20 each, identically or differently, denote a halogenated or unsubstituted alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by C?C, CF.sub.2O, CH?CH, ##STR00395## O, COO or OCO in such a way that O atoms are not linked directly to one another, X.sup.20 each, identically or differently, denote F, Cl, CN, SF.sub.5, SCN, NCS, a halogenated alkyl radical, a halogenated alkenyl radical, a halogenated alkoxy radical or a halogenated alkenyloxy radical, each having up to 6 C atoms, and Y.sup.20-23 each, identically or differently, denote H or F.

14. The liquid crystal mixture according to claim 5 characterised in that it comprises one or more compounds selected from the following formula: ##STR00396## wherein the individual radicals have the following meanings: ##STR00397## denotes ##STR00398## ##STR00399## denotes ##STR00400## R.sup.3 and R.sup.4 each, independently of one another, denote alkyl having 1 to 12 C atoms, wherein, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by O, CH?CH, CO, OCO or COO in such a way that O atoms are not linked directly to one another, Z.sup.y denotes CH.sub.2CH.sub.2, CH?CH, CF.sub.2O, OCF.sub.2, CH.sub.2O, OCH.sub.2, COO, OCO, C.sub.2F.sub.4, CF?CF or a single bond.

15. The liquid crystal mixture according to claim 5, characterised in that it comprises one or more compounds selected from the following formulae: ##STR00401##

16. A liquid crystal display, comprising a liquid crystal mixture according to claim 5.

17. A process for the fabrication of a liquid crystal display device, comprising at least the steps: providing a first substrate which includes a pixel electrode and a common electrode; providing a second substrate, the second substrate being disposed opposite to the first substrate; interposing a liquid crystal mixture according to claim 5; irradiating the liquid crystal mixture with linearly polarised light causing photoalignment of the liquid crystal mixture.

18. The process according to claim 17, characterised in that after irradiation with polarised light the polymerisable compounds of the liquid crystal mixture are cured by irradiation with ultraviolet light.

19. The process according to claim 17 characterised in that the linearly polarised light is ultraviolet light.

20. A Liquid crystal display, obtainable by a process according to claim 17.

21. The liquid crystal display according to claim 20, wherein the liquid crystal display is an IPS or FFS display.

Description

EXAMPLES

[0357] Hereinafter, the present invention is described in more detail and specifically with reference to the Examples, which however are not intended to limit the present invention.

Synthesis Example 1: Ethyl (E)-3-[3-(2-hydroxyethoxy)-4-(4-pentylbiphenyl)]prop-2-enoate

[0358] The starting material 2-fluoro-4-iodo-1-(4-pentyl-phenyl)-benzene was prepared according to a literature procedure by Suzuki-coupling of 5-pentylbenzene boronic acid and 4-bromo-2-fluoro-1-iodo-benzene followed by bromine-lithium exchange and reaction of the lithiated intermediate with iodine.

Stage 1: 2-[5-iodo-2-(4-pentylphenyl)phenoxy]ethanol

[0359] ##STR00365##

[0360] Triethylene glycol dimethyl ether (100 ml), dibenzo-18-crown-6 (1.3 g, 3.6 mmol), and sodium hydride (8 g, 60% dispersion in oil, 200 mmol) are stirred at room temperature. Anhydrous ethylene glycol (40 ml, 720 mmol), is added dropwise over 30 minutes keeping the temperature below 60? C. 2-Fluoro-4-iodo-1-(4-pentyl-phenyl)-benzene (11 g, 30 mmol) is added and the mixture heated to 160? C. over a period of 30 minutes, then stirred overnight at 160? C. The mixture is cooled, water (300 ml) and concentrated hydrochloric acid (20 ml) are added and the mixture is extracted with ethyl acetate (3?100 ml). The combined organic layers are diluted with petrol B.p 40-60? C. (300 ml) and washed with water (400 ml, 2?250 ml). The solvent from the organic layer is removed in vacuo to give an oil. The oil is purified by vacuum flash chromatography on silica with petrol/dichloromethane to give 2-[5-iodo-2-(4-pentylphenyl)phenoxy]-ethanol.

Stage 2: Ethyl (E)-3-[3-(2-hydroxyethoxy)-4-(4-pentylbiphenyl)]prop-2-enoate

[0361] ##STR00366##

[0362] 2-[5-iodo-2-(4-pentylphenyl)phenoxy]ethanol (2.0 g, 5.5 mmol), sodium bicarbonate (1.1 g, 13 mmol), tetra-n-butylammonium bromide (1.8 g, 5.6 mmol), ethyl acrylate (2.4 ml, 22 mmol), palladium acetate (62 mg) and dimethylformamide (22 ml) are heated to 100? C. and held for 6 hours. The mixture is cooled, then acidified with dilute hydrochloric acid (60 ml, 1 M, 60 mmol). The mixture is extracted with ethyl acetate (100 ml). The organic layer is washed with water (2?30 ml). The solvent from the organic layer is removed in vacuo. The oil is purified by vacuum flash chromatography on silica (60 g) eluting with the following; petrol B.p 40-60? C.:dichloromethane:ethyl acetate. The solvent is removed in vacuo and the residue is crystallised from heptane (30 ml) to give ethyl (E)-3-[3-(2-hydroxyethoxy)-4-(4-pentylbiphenyl)]prop-2-enoate.

Example 2: Ethyl (E)-3-[4-(4-pentylphenyl)-3-(3-trimethoxysilylpropoxy)-phenyl]prop-2-enoate

Step 1: Ethyl (E)-3-[3-allyloxy-4-(4-pentylphenyl)phenyl]prop-2-enoate

[0363] ##STR00367##

[0364] 2-Fluoro-4-iodo-1-(4-pentyl-phenyl)-benzene was reacted with sodium hydroxide in triethylene glycol under the same reaction conditions as described in example 1 to give 5-iodo-2-(4-pentylphenyl)phenol. 5-iodo-2-(4-pentylphenyl)phenol (0.5 g, 1.48 mmol), allyl bromide (0.14 ml, 1.62 mmol), potassium carbonate (0.3 g, 2.2 mmol) and butanone (3 ml) were heated at 80? C. for 3 hours. The mixture was cooled and the solvent removed in vacuo. The residue was dissolved in dichloromethane and purified by vacuum flash chromatography on silica (40 g) eluting with dichloromethane. The fractions containing the product were combined and the solvent removed in vacuo to give ethyl (E)-3-[3-allyloxy-4-(4-pentylphenyl)phenyl]prop-2-enoate.

Step 2: Ethyl (E)-3-[4-(4-pentylphenyl)-3-(3-trimethoxysilylpropoxy)-phenyl]prop-2-enoate

[0365] ##STR00368##

[0366] Ethyl (E)-3-[3-allyloxy-4-(4-pentylphenyl)phenyl]prop-2-enoate (0.55 g, 1.46 mmol), trimethoxysilane (0.24 ml, 1.89 mmol), toluene (1 ml), and platinum(0)-1,3-Divinyl-1,1,3,3-tetramethyldisiloxane complex (solution in xylene, 25 mg?2% platinum) were heated at 80? C. overnight. The mixture was cooled, the solvent removed in vacuo and the residue was purified by vacuum flash chromatography on silica (40 g) eluting with toluene:petrol B.p 40-60? C.:dichloromethane:ethyl acetate to give ethyl (E)-3-[4-(4-pentylphenyl)-3-(3-trimethoxysilylpropoxy)-phenyl]prop-2-enoate.

[0367] In analogy to the above described procedures the following examples are obtained:

Example 3

[0368] ##STR00369##

Example 4

[0369] ##STR00370##

Example 5

[0370] ##STR00371##

Example 6

[0371] ##STR00372##

Example 7

[0372] ##STR00373##

Example 8

[0373] ##STR00374##

Example 9

[0374] ##STR00375##

Example 10

[0375] ##STR00376##

Example 11

[0376] ##STR00377##

Example 12

[0377] ##STR00378##

Example 13

[0378] ##STR00379##

Fabrication of Display Cells

[0379] The display cells are made with raw untreated AF glass using 5 ?m spacer beads in Norland 65 adhesive. The cells are assembled by hand and then cured using a high pressure mercury lamp (Omnicure?, 250-450 nm) at 78 mW/cm2 for 60 s.

Cell Filling and Curing

[0380] The LC mixtures are capillary filled on a hot plate at 100? C., then left to stand for a further hour at 100? C. and then irradiated with linearly polarised UV light (50 mW/cm.sup.2) for 60 s with the wire grid polariser being either perpendicular or parallel to the IPS electrodes which have a 10? offset to the edge of the IPS cell glass. The cells are cooled slowly to room temperature at a cooling rate of 5? C. per minute.

Mixture Examples

[0381] A nematic LC host mixture N?1 was prepared as follows:

TABLE-US-00007 Mixture N-1: Composition Compound No. Abbreviation c/% 1 CC-3-V 37.00 2 CCY-3-O1 5.00 3 CCY-3-O2 9.50 4 CCY-4-O2 5.00 5 CPY-2-O2 10.00 6 CPY-3-O2 10.00 7 CY-3-O2 11.50 8 PY-3-O2 12.00 ? 100.0 Physical properties T(N, I) = 73.5? C. n.sub.e (20? C., 589.3 nm) = 1.583 ?n (20? C., 589.3 nm) = 0.1005 ?.sub.? (20? C., 1 kHz) = 3.70 ?? (20? C., 1 kHz) = ?3.65 k.sub.1(20? C.) = 12.7 k.sub.3(20? C.) = 14.7 ?.sub.1 (20? C.) = 93

[0382] A nematic LC host mixture N?2 was prepared as follows:

TABLE-US-00008 Mixture N-2: Composition Compound No. Abbreviation c/% 1 APUQU-2-F 6.00 2 APUQU-3-F 6.00 3 CC-3-V 44.5 4 CC-3-V1 4.00 5 CCP-3OCF.sub.3 7.00 6 CCP-V-1 5.00 7 CPGU-3-OT 3.00 8 PGP-2-2V 5.50 9 PGUQU-3-F 3.00 10 PGUQU-4-F 7.00 11 PGUQU-5-F 3.00 12 PUQU-3-F 6.00 ? 100.0 Physical properties T(N, I) = 73.5? C. n.sub.e (20? C., 589.3 nm) = 1.5902 ?n (20? C., 589.3 nm) = 0.1086 ?.sub.? (20? C., 1 kHz) = 12.9 ?? (20? C., 1 kHz) = 9.6 k.sub.1(20? C.) = 12.4 k.sub.3(20? C.) = 13.8 ?.sub.1 (20? C.) = 67

Mixture Example 1

[0383] A test display is fabricated according to the procedure described above using 2% of the compound from synthesis example 5 in nematic host mixture N?1. The cell is placed between crossed polarisers on a light table and aligned so that a dark state is achieved. Rotation by 45? gives the bright state. Both dark and bright state appear uniform which proves uniform planar alignment.

Mixture Example 2

[0384] A test display is fabricated according to the procedure described above using 2% of the compound from synthesis example 3 in nematic host mixture N?1. The cell is placed between crossed polarisers on a light table and aligned so that a dark state is achieved. Rotation by 45? gives the bright state. Both dark and bright state appear uniform which proves uniform planar alignment.

[0385] The change in transmission of the display was measured as follows: The true bright and true dark transmission voltages were measured with parallel polarisers and crossed polarisers respectively, with no cell. The cell was then placed between the crossed polarisers and the transmission voltage was measured with increasing electric field voltage. The relative transmission (% T) was calculated where 100% is defined as true bright and 0% is defined as true dark, using the following equation:

% T=100((measured value?true dark)/(true bright?true dark))

[0386] The following Table 1 shows the % Transmission values versus the applied voltage.

TABLE-US-00009 TABLE 1 Voltage/V % T 0 1.42 1 1.47 2 4.40 3 16.55 4 32.97 5 44.48 6 49.56 7 50.41 8 49.73 9 47.36 10 45.67 11 43.97 12 42.28

[0387] As can be seen from table 1, a display fabricated using the mixture from Mixture Example 2 containing the compound from example 1 shows excellent switching behaviour.

Mixture Example 3

[0388] A test display is fabricated according to the procedure described above using 2% of the compound from synthesis example 5 in nematic host mixture N?2. The cell is placed between crossed polarisers on a light table and aligned so that a dark state is achieved. Rotation by 45? gives the bright state. Both dark and bright state appear uniform which proves uniform planar alignment.