LIQUID-CRYSTAL MEDIUM COMPRISING POLYMERIZABLE COMPOUNDS

Abstract

A polymerizable compound having absorption in the long UV wavelength range, a liquid-crystal (LC) medium comprising the polymerizable compound, and the use of the compound or LC medium for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of the PSA (polymer sustained alignment) or SA (self-aligning) mode, an LC display of the PSA or SA mode comprising the compound or LC medium, and a process of manufacturing the LC display.

Claims

1. A polymerizable compound of formula I ##STR00512## wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings R.sup.a, R.sup.b P-Sp- or R, wherein at least one of R.sup.a and R.sup.b denotes P-Sp-, A.sup.a, A.sup.b phenylene-1,4,-diyl or naphthalene,2-6-diyl which is optionally substituted by one or more groups L, Z.sup.a, Z.sup.b CHCH, CFCF, CC or a single bond, P a polymerizable group, Sp a spacer group that is optionally substituted by one or more groups P, or a single bond, R straight chain alkyl having 1 to 25 C atoms or branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups are optionally replaced by O, S, CO, COO, OCO, OCOO, CR.sup.0CR.sup.00, CC, ##STR00513## in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl, L F, Cl, Br, CN or straight chain alkyl having 1 to 25 C atoms or branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups are optionally replaced by O, S, CO, COO, OCO, OCOO, N(R.sup.0), Si(R.sup.0R.sup.00), CHCH or CC in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl, R.sup.0, R.sup.00 H or alkyl with 1 to 12 C atoms, r1 0, 1, 2, 3 or 4.

2. The compound according to claim 1, comprising a compound of formula I1 ##STR00514##

3. The compound according to claim 1, comprising one or more compounds selected from the following subformulae: ##STR00515## ##STR00516##

4. An LC medium comprising one or more compounds according to claim 1.

5. The LC medium according to claim 4, additionally comprising one or more compounds of formula II ##STR00517## wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings R.sup.1 and R.sup.2 straight chain, cyclic alkyl having 1 to 25 C atoms or branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups are optionally replaced by O, S, CO, COO, OCO, OCOO, CR.sup.0CR.sup.00, CC, ##STR00518## in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl, A.sup.1 and A.sup.2 a group selected from the following formulae ##STR00519## ##STR00520## wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings Z.sup.1 and Z.sup.2 CH.sub.2CH.sub.2, CHCH, CF.sub.2O, OCF.sub.2, CH.sub.2O, OCH.sub.2, COO, OCO, C.sub.2F.sub.4, CFCF, CHCHCH.sub.2O or a single bond, L.sup.1, L.sup.2, L.sup.3 and L.sup.4 F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F or CHF.sub.2, Y H, F, Cl, CF.sub.3, CHF.sub.2 or CH.sub.3, L.sup.C CH.sub.3 or OCH.sub.3, a1 1 or 2, a2 0 or 1.

6. The LC medium according to claim 5, comprising one or more compounds of formula II selected from the group consisting of compounds of the formulae IIA, IIB, IIC and IID ##STR00521## in which R.sup.2A and R.sup.2B each, independently of one another, denote H, an alkyl or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF.sub.3 or at least monosubstituted by halogen, where, in addition, one or more CH.sub.2 groups in these radicals may be replaced by O, S, ##STR00522## CC, CF.sub.2O, OCF.sub.2, OCO or OCO in such a way that O atoms are not linked directly to one another, L.sup.1 to L.sup.4 each, independently of one another, denote F, Cl, CF.sub.3 or CHF.sub.2, Y denotes H, F, Cl, CF.sub.3, CHF.sub.2 or CH.sub.3, Z.sup.2, Z.sup.2B and Z.sup.2D each, independently of one another, denote a single bond, CH.sub.2CH.sub.2, CHCH, CF.sub.2O, OCF.sub.2, CH.sub.2O, OCH.sub.2, COO, OCO, C.sub.2F.sub.4, CFCF, CHCHCH.sub.2O, p denotes 0, 1 or 2, and q on each occurrence, identically or differently, denotes 0 or 1.

7. The LC medium according to claim 5, additionally comprising one or more compounds of formula III ##STR00523## in which R.sup.11 and R.sup.12 each, independently of one another, denote H, an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by ##STR00524## CC, CF.sub.2O, OCF.sub.2, CHCH, by O, COO or OCO in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, A.sup.3 on each occurrence, independently of one another, denotes a) 1,4-cyclohexenylene or 1,4-cyclohexylene radical, in which one or two non-adjacent CH.sub.2 groups may be replaced by O or S, b) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N, or c) a radical selected from the group consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, wherein the radicals a), b) and c) may be mono- or polysubstituted by halogen atoms, n denotes 0, 1 or 2, Z.sup.1 on each occurrence independently of one another denotes COO, OCO, CF.sub.2O, OCF.sub.2, CH.sub.2O, OCH.sub.2, CH.sub.2, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, CHCHCH.sub.2O, C.sub.2F.sub.4, CH.sub.2CF.sub.2, CF.sub.2CH.sub.2, CFCF, CHCF, CFCH, CHCH, CC or a single bond, L.sup.11 and L.sup.12 each, independently of one another, denote F, Cl, CF.sub.3 or CHF.sub.2, and W denotes O or S.

8. The LC medium according to claim 5, additionally comprising one or more compounds of formula IV ##STR00525## in which R.sup.41 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, and R.sup.42 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms, an unsubstituted alkenyl radical having 2 to 7 C atoms.

9. The LC medium according to claim 5, additionally comprising one or more compounds of formula V ##STR00526## in which R.sup.51 and R.sup.52 independently of one another, denote an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkenyl radical having 2 to 7 C atoms, or an unsubstituted alkoxy radical having 1 to 6 C atoms, ##STR00527## identically or differently, denote ##STR00528## Z.sup.51, Z.sup.52 each, independently of one another, denote CH.sub.2CH.sub.2, CH.sub.2O, CHCH, CC, COO or a single bond, and n is 1 or 2.

10. The LC medium according to claim 5, additionally comprising one or more additives selected from the group consisting of stabilizers, chiral dopants, polymerization initiators and self alignment additives.

11. A process of preparing an LC medium, comprising the steps of mixing one or more polymerizable compounds comprising a compound of formula I ##STR00529## wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings R.sup.a, R.sup.b P-Sp- or R, wherein at least one of R.sup.a and R.sup.b denotes P-Sp-, A.sup.a, A.sup.b phenylene-1,4,-diyl or naphthalene,2-6-diyl which is optionally substituted by one or more groups L, Z.sup.a, Z.sup.b CHCH, CFCF, CC or a single bond, P a polymerizable group, Sp a spacer group that is optionally substituted by one or more groups P, or a single bond, R straight chain alkyl having 1 to 25 C atoms or branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups are optionally replaced by O, S, CO, COO, OCO, OCOO, CR.sup.0CR.sup.00, CC, ##STR00530## in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl, L F, Cl, Br, CN or straight chain alkyl having 1 to 25 C atoms or branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups are optionally replaced by O, S, CO, COO, OCO, OCOO, N(R.sup.0), Si(R.sup.0R.sup.00), CHCH or CC in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl, R.sup.0, R.sup.00 H or alkyl with 1 to 12 C atoms, r1 0, 1, 2, 3 or 4, with one or more compounds of formula II ##STR00531## wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings R.sup.1 and R.sup.2 straight chain, cyclic alkyl having 1 to 25 C atoms or branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups are optionally replaced by O, S, CO, COO, OCO, OCOO, CR.sup.0CR.sup.00, CC, ##STR00532## in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl, A.sup.1 and A.sup.2 a group selected from the following formulae ##STR00533## ##STR00534## wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings Z.sup.1 and Z.sup.2 CH.sub.2CH.sub.2, CHCH, CF.sub.2O, OCF.sub.2, CH.sub.2O, OCH.sub.2, COO, OCO, C.sub.2F.sub.4, CFCF, CHCHCH.sub.2O or a single bond, L.sup.1, L.sup.2, L.sup.3 and L.sup.4 F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F or CHF.sub.2, Y H, F, Cl, CF.sub.3, CHF.sub.2 or CH.sub.3, L.sup.C CH.sub.3 or OCH.sub.3, a1 1 or 2, a2 0 or 1, and optionally with further liquid-crystalline compounds and/or additives, and optionally polymerizing the polymerizable compounds.

12. An LC display comprising an LC medium as defined in claim 4.

13. The LC display according to claim 12, which is a PSA or SA display.

14. The LC display according to claim 13, which is a PS-VA, PS-IPS, PS-FFS or SA-VA display.

15. The LC display according to claim 13, comprising two substrates, at least one of which is transparent to light, an electrode provided on each substrate or two electrodes provided on only one of the substrates, and located between the substrates a layer of an LC medium comprising one or more polymerizable compounds comprising: a compound of formula I ##STR00535## wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings R.sup.a, R.sup.b P-Sp- or R, wherein at least one of R.sup.a and R.sup.b denotes P-Sp-, A.sup.a, A.sup.b phenylene-1,4,-diyl or naphthalene,2-6-diyl which is optionally substituted by one or more groups L, Z.sup.a, Z.sup.b CHCH, CFCF, CC or a single bond, P a polymerizable group, Sp a spacer group that is optionally substituted by one or more groups P, or a single bond, R straight chain alkyl having 1 to 25 C atoms or branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups are optionally replaced by O, S, CO, COO, OCO, OCOO, CR.sup.0CR.sup.00, CC, ##STR00536## in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl, L F, Cl, Br, CN or straight chain alkyl having 1 to 25 C atoms or branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups are optionally replaced by O, S, CO, COO, OCO, OCOO, N(R.sup.0), Si(R.sup.0R.sup.00), CHCH or CC in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl, R.sup.0, R.sup.00 H or alkyl with 1 to 12 C atoms, r1 0, 1, 2, 3 or 4; a compound of formula I1 ##STR00537## or one or more compounds selected from the following subformulae: ##STR00538## ##STR00539## and optionally comprising: one or more compounds of formula II ##STR00540## wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings R.sup.1 and R.sup.2 straight chain, cyclic alkyl having 1 to 25 C atoms or branched or cyclic alkyl having 3 to 25 C atoms, wherein one or more non-adjacent CH.sub.2-groups are optionally replaced by O, S, CO, COO, OCO, OCOO, CR.sup.0CR.sup.00, CC, ##STR00541## in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl, A.sup.1 and A.sup.2 a group selected from the following formulae ##STR00542## ##STR00543## wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings Z.sup.1 and Z.sup.2 CH.sub.2CH.sub.2, CHCH, CF.sub.2O, OCF.sub.2, CH.sub.2O, OCH.sub.2, COO, OCO, C.sub.2F.sub.4, CFCF, CHCHCH.sub.2O or a single bond, L.sup.1, L.sup.2, L.sup.3 and L.sup.4 F, Cl, OCF.sub.3, CF.sub.3, CH.sub.3, CH.sub.2F or CHF.sub.2, Y H, F, Cl, CF.sub.3, CHF.sub.2 or CH.sub.3, L.sup.C CH.sub.3 or OCH.sub.3, a1 1 or 2, a2 0 or 1; one or more compounds of formula II selected from the group consisting of compounds of the formulae IIA, IIB, IIC and IID ##STR00544## in which R.sup.2A and R.sup.2B each, independently of one another, denote H, an alkyl or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF.sub.3 or at least monosubstituted by halogen, where, in addition, one or more CH.sub.2 groups in these radicals may be replaced by O, S, ##STR00545## CC, CF.sub.2O, OCF.sub.2, OCO or OCO in such a way that O atoms are not linked directly to one another, L.sup.1 to L.sup.4 each, independently of one another, denote F, Cl, CF.sub.3 or CHF.sub.2, Y denotes H, F, Cl, CF.sub.3, CHF.sub.2 or CH.sub.3, Z.sup.2, Z.sup.2B and Z.sup.2D each, independently of one another, denote a single bond, CH.sub.2CH.sub.2, CHCH, CF.sub.2O, OCF.sub.2, CH.sub.2O, OCH.sub.2, COO, OCO, C.sub.2F.sub.4, CFCF, CHCHCH.sub.2O, p denotes 0, 1 or 2, and q on each occurrence, identically or differently, denotes 0 or 1; one or more compounds of formula III ##STR00546## in which R.sup.11 and R.sup.12 each, independently of one another, denote H, an alkyl or alkoxy radical having 1 to 15 C atoms, where one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by ##STR00547## CC, CF.sub.2O, OCF.sub.2, CHCH, by O, COO or OCO in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, A.sup.3 on each occurrence, independently of one another, denotes a) 1,4-cyclohexenylene or 1,4-cyclohexylene radical, in which one or two non-adjacent CH.sub.2 groups may be replaced by O or S, b) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N, or c) a radical selected from the group consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, wherein the radicals a), b) and c) may be mono- or polysubstituted by halogen atoms, n denotes 0, 1 or 2; one or more compounds of formula IV ##STR00548## in which R.sup.41 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, and R.sup.42 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms, an unsubstituted alkenyl radical having 2 to 7 C atoms; one or more compounds of formula V ##STR00549## in which R.sup.51 and R.sup.52 independently of one another, denote an unsubstituted alkyl radical having 1 to 7 C atoms, an unsubstituted alkenyl radical having 2 to 7 C atoms, or an unsubstituted alkoxy radical having 1 to 6 C atoms, ##STR00550## identically or differently, denote ##STR00551## Z.sup.51, Z.sup.52 each, independently of one another, denote CH.sub.2CH.sub.2, CH.sub.2O, CHCH, CC, COO or a single bond, and n is 1 or 2; and/or one or more additives selected from the group consisting of stabilizers, chiral dopants, polymerization initiators and self alignment additives, wherein the polymerizable compounds are polymerized between the substrates of the display by UV photopolymerization.

16. The process for the production of an LC display according to claim 15, comprising the steps of providing the LC medium between the substrates of the display, and polymerizing the polymerizable compounds by irradiation with UV light, while a voltage is applied to the electrodes of the display.

17. The process according to claim 16, wherein the UV light has a wavelength>360 nm.

18. The process according to claim 17, wherein the UV light has a wavelength in the range from 360 to 380 nm.

19. The process according to claim 16, wherein the irradiation with UV light is carried out using an UV-LED lamp.

Description

EXAMPLES

[0452] The following examples explain the present invention without restricting it. However, they show the person skilled in the art preferred mixture concepts with compounds preferably to be employed and the respective concentrations thereof and combinations thereof with one another. In addition, the examples illustrate which properties and property combinations are accessible.

[0453] In addition, the following abbreviations and symbols are used: [0454] V.sub.0 threshold voltage, capacitive [V] at 20 C., [0455] n.sub.e extraordinary refractive index at 20 C. and 589 nm, [0456] n.sub.o ordinary refractive index at 20 C. and 589 nm, [0457] n optical anisotropy at 20 C. and 589 nm, [0458] .sub. dielectric permittivity perpendicular to the director at 20 C. and 1 kHz, [0459] .sub. dielectric permittivity parallel to the director at 20 C. and 1 kHz, [0460] dielectric anisotropy at 20 C. and 1 kHz, [0461] cl.p., T(N,I) clearing point [ C.], [0462] .sub.1 rotational viscosity at 20 C. [mPa.Math.s], [0463] K.sub.1 elastic constant, splay deformation at 20 C. [pN], [0464] K.sub.2 elastic constant, twist deformation at 20 C. [pN], [0465] K.sub.3 elastic constant, bend deformation at 20 C. [pN].

[0466] Unless explicitly noted otherwise, all concentrations in the present application are quoted in percent by weight and relate to the corresponding mixture as a whole, comprising all solid or liquid-crystalline components, without solvents.

[0467] Unless explicitly noted otherwise, all temperature values indicated in the present application, such as, for example, for the melting point T(C,N), the transition from the smectic (S) to the nematic (N) phase T(S,N) and the clearing point T(N,I), are quoted in degrees Celsius ( C.). M.p. denotes melting point, cl.p.=clearing point. Furthermore, C=crystalline state, N=nematic phase, S=smectic phase and I=isotropic phase. The data between these symbols represent the transition temperatures.

[0468] All physical properties are and have been determined in accordance with Merck Liquid Crystals, Physical Properties of Liquid Crystals, Status November 1997, Merck KGaA, Germany, and apply for a temperature of 20 C., and n is determined at 589 nm and at 1 kHz, unless explicitly indicated otherwise in each case.

[0469] The term threshold voltage for the present invention relates to the capacitive threshold (V.sub.0), also known as the Freedericks threshold, unless explicitly indicated otherwise. In the examples, the optical threshold may also, as generally usual, be quoted for 10% relative contrast (V.sub.10).

[0470] Unless stated otherwise, the process of polymerizing the polymerizable compounds in the PSA displays as described above and below is carried out at a temperature where the LC medium exhibits a liquid crystal phase, preferably a nematic phase, and most preferably is carried out at room temperature.

[0471] Unless stated otherwise, methods of preparing test cells and measuring their electrooptical and other properties are carried out by the methods as described hereinafter or in analogy thereto.

[0472] The display used for measurement of the capacitive threshold voltage consists of two plane-parallel glass outer plates at a separation of 25 m, each of which has on the inside an electrode layer and an unrubbed polyimide alignment layer on top, which effect a homeotropic edge alignment of the liquid-crystal molecules.

[0473] The PSVA display or PSVA test cell used for measurement of the tilt angles consists of two plane-parallel glass outer plates at a separation of 4 m unless stated otherwise, each of which has on the inside an electrode layer and a polyimide alignment layer on top, where the two polyimide layers are rubbed antiparallel to one another and effect a homeotropic edge alignment of the liquid-crystal molecules. The SAVA display or test cell has the same structure but wherein one or both polyimide layers are omitted.

[0474] The polymerizable compounds are polymerized in the display or test cell by irradiation with UV light of defined intensity for a prespecified time, with a voltage simultaneously being applied to the display (usually 10 V to 30 V alternating current, 1 kHz). In the examples, unless indicated otherwise, a metal halide lamp and an intensity of 100 mW/cm.sup.2 is used for polymerization. The intensity is measured using a standard meter (Hoenle UV-meter high end with UV sensor).

[0475] The tilt angle is determined using the Mueller Matrix Polarimeter AxoScan from Axometrics. A low value (i.e. a large deviation from the 90 angle) corresponds to a large tilt here.

[0476] Unless stated otherwise, the term tilt angle means the angle between the LC director and the substrate, and LC director means in a layer of LC molecules with uniform orientation the preferred orientation direction of the optical main axis of the LC molecules, which corresponds, in case of calamitic, uniaxially positive birefringent LC molecules, to their molecular long axis.

Example 1

[0477] Compound 1 is prepared as follows

##STR00503##

a) Synthesis of Bromide A

[0478] 50.00 g (277.40 mmol) 9,10-Dihydrophenanthrene is dissolved in 750 mL

##STR00504##

[0479] Dichloromethane and 510.00 mg (3.14 mmol) Iron powder is added and the mixture is cooled to 5 C. 30.00 mL (585.70 mmol) Br.sub.2 dissolved in 450 mL dichloromethane is being added dropwise and the reaction mixture is stirred over night at room temperature. The surplus Br.sub.2 is quenched by adding dropwise NaHSO.sub.3 solution. Additional water is being added and the layers are separated. The organic layer is washed with Na.sub.2S.sub.2O.sub.3 solution, dried over Na.sub.2SO.sub.4, filtered and evaporated under vacuum. The product is crystallized with acetone.

[0480] .sup.1H NMR (500 MHz, Chloroform-d) 7.58 (d, J=8.3 Hz, 2H), 7.44 (dd, J=8.4, 1.9 Hz, 2H), 7.41 (d, J=1.9 Hz, 2H), 2.86 (s, 4H).

b) Synthesis of Boronic Acid B

[0481] ##STR00505##

[0482] 5.50 g (19.95 mmol) bromide A and 5.20 mL (22.67 mmol) triisopropyl borate are dissolved in 80 mL THF, cooled with dry ice to 50 C. and n-buthyllithium (1.6 M in hexane) is added slowly so that the temperature does not exceed minus 45 C. The reaction mixture is stirred for 60 min at minus 50 C. The reaction mixture is quenched with 50 mL 2N HCl and is carefully poured on 50 mL 2N HCl and methyl tert-butyl ether (MTBE). The layers are separated, the water layer is extracted with MTBE and the combined organic layers are washed with water, brine and dried over Na.sub.2SO.sub.4, filtered and evaporated under vacuum to yield an colorless reaction product which is directly used in the next synthesis transformation.

c) Synthesis of Alcohol C

[0483] ##STR00506##

[0484] 6.30 g (11.0 mmol, 51%) is dissolved in 50.0 mL THF and a mixture of 2.20 mL water and 1.70 mL acetic acid (100%) is added. 2.50 mL H.sub.2O.sub.2 (29.07 mmol, 35% solution water) is added dropwise and the exothermic reaction is cooled with an ice water cooling bath. The mixture is stirred for 17 h at room temperature. Water is added and the mixture is extracted with MTBE. The combined organic layers are washed several times with ammonium iron (II) sulfate to remove the remaining H.sub.2O.sub.2. The organic layer is then washed with water and dried over Na.sub.2SO.sub.4, filtered and evaporated under vacuum. The crude product is filtered with dichloromethane over silica gel, combined and evaporated under vacuum to give the product a yellow, crystalline solid.

[0485] .sup.1H NMR (500 MHz, Chloroform-d) 7.51 (d, J=8.4 Hz, 1H), 7.44 (d, J=8.4 Hz, 1H), 7.35-7.24 (m, 2H), 6.70 (dd, J=8.4, 2.7 Hz, 1H), 6.64 (d, J=2.7 Hz, 1H), 4.68 (s, 1H), 2.89-2.54 (m, 4H).

d) Synthesis of Boronic Ester D

[0486] ##STR00507##

[0487] 2.40 g (8.42 mmol) alcohol C, 2.40 g (9.45 mmol) bis(pinacolato)boron and 3.30 g (23.44 mmol) KOAc are dissolved in 25 mL 1,4-dioxane. 0.20 g (0.27 mmol) Pd(dppf)Cl.sub.2 is added and the reaction is stirred under reflux for 5 h. It is cooled to room temperature and the reaction mixture is poured on 2N HCl and acetic acid ethylester (EE). The organic layer is washed with water and brine and dried over Na.sub.2SO.sub.4, filtered and evaporated under vacuum. The product is purified by column chromatography with dichloromethane and the combined product is evaporated under vacuum to yield a colorless oil.

[0488] .sup.1H NMR (500 MHz, Chloroform-d) 7.75 (dd, J=7.7, 1.2 Hz, 1H), 7.71-7.65 (m, 3H), 6.80 (dd, J=8.4, 2.7 Hz, 1H), 6.74 (d, J=2.7 Hz, 1H), 4.82 (s, 1H), 2.89 (dd, J=8.4, 4.8 Hz, 2H), 2.83 (dd, J=9.5, 5.6 Hz, 2H), 1.39 (s, 12H).

e) Synthesis of Bis-Alcohol E

[0489] ##STR00508##

[0490] 1.60 g (7.64 mmol) 4-bromo-3-methoxyphenol are dissolved in 20.0 mL THF and 1.60 g (11.57 mmol) K.sub.2CO.sub.3 are being added with 10 mL water. The mixture is degassed with Argon for 30 min and the mixture is heated to 65 C. 50.00 mg (0.14 mmol) CataCxium A and 65.00 mg (0.07 mmol) Pd.sub.2(dba).sub.3 is added. 2.30 g (6.90 mmol) of boronic ester E (dissolved in 20 mL THF) is added dropwise and the mixture is stirred for 2.5 h under reflux. The mixture is cooled to room temperature and the organic layer is separated. The water layer is extracted with EE and the combined organic layer is washed with brine, dried over Na.sub.2SO.sub.4, filtered and evaporated under vacuum. The product is filtered over silica gel with dichloromethane and MTBE (1:1) and crystallized out of MTBE.

[0491] .sup.1H NMR (500 MHz, Chloroform-d) 9.50 (s, 2H), 7.63 (dd, J=10.2, 8.2 Hz, 2H), 7.30 (dd, J=8.1, 2.0 Hz, 1H), 7.25 (d, J=1.8 Hz, 1H), 7.11 (d, J=8.3 Hz, 1H), 6.71 (dd, J=8.3, 2.6 Hz, 1H), 6.67 (d, J=2.6 Hz, 1H), 6.51 (d, J=2.3 Hz, 1H), 6.44 (dd, J=8.2, 2.2 Hz, 1H), 3.72 (s, 3H), 2.84-2.66 (m, 4H).

[0492] MS [APCl] 319.13=M+H.sup.+

f) Synthesis of Compound 1

[0493] ##STR00509##

[0494] 3.40 g (10.00 mmol) bisalcohol E, 2.60 mL (30.65 mmol) methacrylic acid (stabilized, Merck 800578), 0.25 g (2.05 mmol) 4-(dimethylamino)-pyridine are dissolved in 100 mL dichloromethane and cooled to 2 C. 5.20 mL (30.15 mmol) 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide is added dropwise and the reaction mixture is stirred over night at room temperature. The reaction mixture is filtered over 150 g silica gel and 100 g alox (basic) with dichloromethane. The reaction product is evaporated under vacuum and crystallized with MTBE to yield the product as a colorless solid.

[0495] .sup.1H NMR (500 MHz, Chloroform-d) 7.94-7.88 (m, 1H), 7.86 (d, J=8.2 Hz, 1H), 7.44 (dd, J=8.0, 1.9 Hz, 1H), 7.42-7.34 (m, 2H), 7.17-7.09 (m, 2H), 6.99 (d, J=2.2 Hz, 1H), 6.86 (dd, J=8.2, 2.2 Hz, 1H), 6.31 (dt, J=7.3, 1.3 Hz, 2H), 5.93 (dq, J=5.4, 1.6 Hz, 2H), 3.79 (s, 3H), 2.88 (s, 4H), 2.03 (dt, J=5.1, 1.3 Hz, 6H).

[0496] MS [APCl] 455.18=M+H.sup.+

[0497] The absorption wavelength of compound 1 at an extinction coefficient of E=0.5 is measured as 357 nm for a solution in DCM at a concentration of 3 g/L.

Examples 2-5

[0498] Compounds 2 to 5 are prepared in analogy to Example 1.

##STR00510##

Use Example AComparison of Physical Properties

[0499] The absorption wavelength at an extinction coefficient of E=0.5 is determined for compound RM-1 of prior art by the method as described in Example 1. This wavelength is useful to characterize the wavelength dependence of the UV photopolymerization of the compound.

##STR00511##

[0500] The UV absorption wavelength of compounds 1 and 2 of Example 1 and 2 are compared with that of compound RM-1 of prior art. The results are shown in Table 1.

TABLE-US-00007 TABLE 1 UV Absorption RM-1 1 2 UV absorption wavelength 320 357 361 (nm) at E = 0.5

[0501] From Table 1 it can be seen that compounds 1 and 2 according to the invention have a long absorption wavelength, which is higher than that of compound RM-1. Compounds 1 and 2 are thus especially suitable for UV photopolymerization at longer wavelengths or faster polymerization at shorter wavelengths.

[0502] Polymerizable Mixtures

[0503] The nematic LC host mixture N1 is formulated as follows

TABLE-US-00008 B(S)-2O-O4 4.50% cl. p. 76 C. B(S)-2O-O5 5.00% n 0.1120 BCH-32 6.00% 3.0 CC-3-V 47.50% .sub. 3.5 CLY-3-O2 6.00% .sub.1 74 mPa .Math. s CPY-2-O2 10.50% K.sub.1 14.2 CPY-3-O2 10.50% K.sub.3 14.5 PY-1-O2 10.00% K.sub.3/K.sub.1 1.06 V.sub.0 2.31 V

[0504] Polymerizable mixture P1.1 is prepared by adding the polymerizable compound 1 of Example 1 to the nematic LC host mixture N1 at a concentration of 0.3%.

[0505] Polymerizable mixture P1.2 is prepared by adding the polymerizable compound 1 of Example 1 to the nematic LC host mixture N1 at a concentration of 0.45%.

[0506] Polymerizable mixture P1.3 is prepared by adding the polymerizable compound 2 of Example 2 to the nematic LC host mixture N1 at a concentration of 0.3%.

[0507] Polymerizable mixture P1.4 is prepared by adding the polymerizable compound 2 of Example 2 to the nematic LC host mixture N1 at a concentration of 0.45%.

[0508] Low Temperature Stability (LTS)

[0509] The LTS of compounds 1 and 2 is measured in the host mixture N1. The results are shown in Table 2.

TABLE-US-00009 TABLE 2 LTS LTS Mixture (20 C.) P1.1 792 h P1.2 624 h P1.3 576 h P1.4 480 h

[0510] It can be seen that compounds 1 and 2 have a good LTS in the nematic host N1 even at a higher concentration of 0.45% (P1.2 and P1.4).

Use Example BPolymerizable Mixtures

[0511] For comparison purposes the polymerizable reference mixture C1 is prepared by adding compound RM-1 of prior art to the nematic LC host mixture N1 at a concentration of 0.3%. Based on the UV-Vis absorption data shown in Table 1 above, it is obvious that compound RM-1 will not react with UV-LED emission centered around 365 nm because of the lack of overlap of absorption with the UV-LED emission. Therefore, in the following the polymerization of compound RM-1 is carried out with a C-type fluorescent lamp having an emission peak at 313 nm, while compounds 1 and 2 are polymerized with an UV-LED lamp showing emission centered around 365 nm.

[0512] For polymerization of polymerizable compounds 1 and 2 test cells containing the polymerizable mixture are exposed to UV light in a two step process. In UV1 step a voltage is applied (20 V.sub.pp square wave, 200 Hz). In UV2 step no voltage is applied. The other conditions are as follows:

[0513] UV1 (LED lamp): 20 mW/cm.sup.2 at room temperature, 210 s for 0.45%; 325 s for 0.3% UV2 (LED lamp): 10 mW/cm.sup.2 at RT, 180 min

[0514] For polymerization of the polymerizable compound RM-1 test cells containing the polymerizable mixture are irradiated using conventional lamps to polymerize the compound in two steps as described above. The conditions are as follows.

[0515] UV1 (C-type fluorescent lamp): 4.5 mW/cm.sup.2 at room temperature, 150 s

[0516] UV2 (C-type fluorescent lamp): 0.5 mW/cm.sup.2 at room temperature, 120 min

[0517] Tilt Stability

[0518] Tilt stability, i.e. the change of the tilt angle after repeated electric stress, is a criterion for evaluating the risk of image sticking. A low value for the change of the tilt angle indicates a high tilt stability and a low potential risk of image sticking.

[0519] For determining the tilt stability the test cells after polymerization as described above are electrically stressed with a square wave of 60V.sub.PP at 60 Hz for 72 h. After a relaxation time of 5-10 min the tilt angles are measured using the Otsuka T_RETS-10 system.

[0520] The change of the tilt angle tilt is determined according to equation (1)

tilt.sub.after stresstilt.sub.after tilt generation=tilt(1)

[0521] and is shown in Table 3 below.

[0522] The lower the value of tilt, the higher is the tilt stability.

TABLE-US-00010 TABLE 3 Tilt Stability Mixture tilt/ C1* 0.5 P1.1** 0.7 P1.2** 0.5 P1.4** 0.5 *UV C-type fluorescent lamp **365 nm UV-LED lamp

[0523] From Table 3 it can be seen that polymerizable mixtures P1.1, P1.2 and P1.4 according to the invention show good tilt stability.

[0524] Voltage Holding Ratio (VHR)

[0525] The VHR of the polymerisable LC media is measured at 60 C. with application of a voltage of 1 V/0.6 Hz initial and after UV exposure. Light stress usually causes the decrease of VHR in LC mixtures, therefore the smaller the absolute decrease of VHR value after stress, the better performance for display applications.

[0526] The results are shown in Table 4.

TABLE-US-00011 TABLE 4 VHR VHR (%) VHR (%) Mixture Initial after 2 h UV C1* 99.6 76.2 P1.1** 99.7 88.1 P1.2** 99.7 97.1 P1.3** 99.7 88.4 P1.4** 99.7 88.9 *UV C-type fluorescent lamp **365 nm UV-LED lamp

[0527] From Table 4 it can be seen that the VHR values of the polymerizable mixtures P1.1 to P1.4 according to the invention are significantly higher than that of polymerizable mixture C1 especially when using a higher concentration of compound 1 or 2.

[0528] Overall the results demonstrate that the polymerizable compounds of formula I are suitable for use in PSA displays prepared by a polymerization process using long UV wavelengths>350 nm, and especially using UV-LED lamps.