GB2388599A - Polymerisable mesogenic tolane compounds - Google Patents

Abstract

The invention relates to new polymerisable mesogenic or liquid crystalline tolane compounds, to polymerisable mesogenic or liquid crystalline mixtures and anisotropic polymers prepared thereof, and to the use of the new compounds and the mixtures and polymers prepared thereof in optical and electrooptical devices, adhesives, synthetic resins with anisotropic mechanical properties, cosmetics, diagnostics, liquid crystal pigments, decorative and security applications, nonlinear optics, optical information storage, electronic devices like organic field effect transistors (FET or OFET), electroluminescent devices, or as chiral dopants.

Description

- 1 2388599

Polymerisable Tolanes Field of the Invention

5 The invention relates to new Polymerisable mesogenic or liquid crystalline tolane compounds, to Polymerisable mesogenic or liquid crystalline mixtures and anisotropic polymers prepared thereof, and to the use of the new compounds and the mixtures and polymers prepared thereof in optical and electrooptical devices, adhesives, 10 synthetic resins with anisotropic mechanical properties, cosmetics, diagnostics, liquid crystal pigments, decorative and security applications, nonlinear optics, optical information storage, electronic devices like organic field effect transistors (FET or OFET),

electroluminescent devices, or as chiral dopants.

Background and Prior Art

Polymerisable mesogenic or liquid crystalline compounds, which are also known as reactive mesogenic compounds, have been described 20 in prior art for various purposes. For example, they can be usd for

the preparation of linear or crosslinked liquid crystal side chain polymers Furthermore, they can be aligned in their liquid crystal phase and subsequently polymerized in situ to give linear or crosslinked liquid crystal polymer films with uniform orientation of 25 high quality. These films can be used as optical elements like polarisers or compensators in flat panel displays, as described for example in EP 0 397 263, WO 98/00475, WO 98/04651 or WO 98/12584.

30 Polymerisable mesogenic compounds have also been suggested for use in polymerized cholesteric liquid crystal films or coatings that show selective reflection of visible light and are suitable as optical films like narrowband or broadband reflective polarizers or colour filters as described for example in EP 0 606 940 or WO 97/3521 g, or 35 for the preparation of liquid crystal pigments, as described for example in WO 97/30136. Other important fields of use are security

- 2 markings as described for example in US 5,678,863 or hot stamping foils as described for example in Go 2,357,061.

Further to the use as optical films in displays, polymerisable 5 mesogenic compounds have been suggested for use in the active, switchable layer of a liquid crystal display.

For example, displays are known which are switched between transparent and scattering states and comprise a low molar mass 10 liquid crystal (LC) medium and a phase-separated polymerized liquid crystal material, like for example PDLC (polymer dispersed liquid crystal) displays as described in WO 93/22397, or polymer gel or polymer network displays of the scattering type, as described in US 5,538,768, US 5,543,075 or ESP 0 451 905.

Furthermore, displays are known wherein a low molar mass LC medium is switched between two non-scattering states, like conventional displays of e.g. the TN or STN, ECB, VA or IPS mode, and which further comprise a polymerised liquid crystal material in 20 order to create a multidomain structure to improve the contrast at wide viewing angles or to stabilise the different switching states in order to reduce the driving voltage and the switching times. Such displays are described for example in US 5,189, 540, US 6,177,972, EP 0 903 392, and Hasebe et al., Jpn. J. Appl. Phys. 1994, 33, 6245.

For the above applications, usually mixtures of two or more polymerisable mesogenic compounds are used, as they have lower melting points and broader liquid crystal phases than single compounds. It is desired to have available polymerisable mixtures 30 exhibiting a liquid crystal phase, preferably a nematic or chiral nematic phase, at room temperature, so that it is possible to carry out alignment and polymerization at low temperatures. For this purpose, it is advantageous if the single polymerisable compounds do already exhibit broad liquid crystalline phases.

( - 3 For use in the switchable layer of liquid crystal displays, where they are typically mixed with a low molar mass LC medium, it is often required that the polymerisable mesogenic compounds have properties, like the liquid crystal phase range and birefringence, that 5 are similar to those of the LC medium. When used in switchable displays that are not of the scattering type, and where the polymerized material is not macroscopically phase separated from the low molar mass LC medium, the polymerisable compounds should preferably show good miscibility with the LC medium.

The polymerisable mesogenic compounds described in prior art,

however, often negatively affect the liquid crystal phase behaviour of LC mixtures, show poor solubility in low molar mass LC media and have unfavourably low values of the birefringence.

Polymerizable mesogenic tolanes or phenylacetylenes have been reported in prior art to show high birefringence values, and have

been disclosed e.g. in JP-A-05-339189, JP-A-07-017910, EP-A-O 659 865, JPA-08-231958, JP-A-11-147853 and GB-A-2 351 734.

20 However, these compounds often do not have sufficiently high birefringence or, when used in an LC mixture, do often negatively influence the properties of the mixture.

Thus, there is a demand for polymerisable mesogenic compounds 25 that do not have the disadvantages mentioned above, in particular for compounds that have high birefringence, which can be used for the preparation of oriented liquid crystal polymer films or as! compounds in the active layer of switchable LC devices in a mixture with low molar mass LC media.

Furthermore, regarding the broad range of applications for polymerisable mesogenic compounds it is desirable for the expert to have available further compounds of this type which are easy to; synthesize and fulfill the various requirements as described above.

- 4 It was an aim of the invention to provide polymerisable mesogenic compounds with the advantageous properties mentioned above, thus extending the pool of polymerisable mesogeniG compounds available to the expert. Other aims of the present invention are immediately 5 evident to the person skilled in the art from the following detailed description.

It was found that these aims can be achieved by providing polymerisable tolanes according to the present invention.

Summary of the Invention

One object of the present invention are polymerisable compounds of formula I (L)r (L)r P-Sp-X-(A -Z1)ml=(Z2 A2) R wherein P is a polymerisable group,; 25 Sp is a spacer group or a single bond, O! X is-O,-S-,-CO-,-COO-,-OCO-,-CH CH-,-OCO-O-,-S CO-, -CO-S-, -CO-N R -, -NR -CO-, -OCH2-, -CH2O-, -SCH2

30, -CH2S-, -CH=CH-COO-, -OOC-CH=CH-, CH2CH2 or a single bond, Z' and Z2 are each independently-COO-, -OCO-, -CH2CH2-,; -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-,

35 -CF2S-, -SCF2-, -CH2CH2-, -CF2CH2-, -CH2CF2-,

( - -CF2CF2-, -CH-CH-, -CH-CH-, -CF=CH-, -CH=CF-,

CF=CF-, -CH=CH-COO-, -OCO-CH=CH-, -C-C- or a I single bond, 5 A' and A2 are each independently an aliphatic or aromatic carbocyclic or heterocyclic group with up to 16 C atoms that may also comprise fused rings and may be unsubstituted, mono- or polysubstituted with L, 10 m1 and m2 are each independently 0, 1 or 2, with m1 m2 c 4, R is straight chain or branched alkyl with up to 25 C-atoms, which may be unsubstituted, monoor polysubstituted by F. Cl, Br, I or CN, it being also possible for one or more non 15 adjacent CH2 groups to be replaced, in each case independently from one another, by -O-, -S-, -NH-, -NR -, SiR R -, -CO-, -COO-, -OCO-, -OCO-O-, -S-CO-, -CO-S-, SO2, -SO-O-, -O-SO-, -CH=CH- orC_C- in such a manner that O and/or S atoms are not linked directly to one another, with the proviso that one or more CH2 groups are replaced, in each case independently from one another, by -S-, -S CO-, -CO-S-, -SO2- , -SO-O- or O-SO-, 25 R and R are independently of each other H or alkyl with 1 to 4 C atoms, is F. Cl, Br, I, CN, NO2 or alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkylcarbonlyoxy with 1 to 7 C atoms, 30 wherein one or more H atoms may be substituted by F or Cl, and r isO,1, 2,30r4. 35 Another object of the present invention is a polymerisable liquid crystal mixture comprising at least one compound of formula 1.

( - 6 Another object of the present invention is an anisotropic polymer or polymer film prepared from one or more compounds of formula I or from a polymerisable liquid crystal mixture comprising at least one 5 compound of formula 1.

Another object of the present invention is the use of the polymerisable compounds of formula 1, the polymerisable mixtures and polymers prepared thereof in optical films, polarisers, 10 compensators, beam splitters, reflective films, alignment layers, colour filters, holographic elements, hot stamping foils, coloured images, decorative or security markings, liquid crystal pigments, adhesives, synthetic resins with anisotropic mechanical properties, cosmetics, diagnostics, nonlinear optics, optical information storage, 15 as chiral dopants, in electronic devices like for example field effect

transistors (FET) as components of integrated circuitry, as thin film transistors in flat panel display applications or for Radio Frequency Identification (RFID) tags, or in semiconducting components for organic light emitting diode (OLED) applications such as 20 electroluminescent displays or backlights of e.g. liquid crystal displays, for photovoltaic or sensor devices, as electrode materials in batteries, as photoconductors, or for electrophotographic applications like electrophotographic recording.

25 Another object of the present invention is a liquid crystal display comprising in its active layer at least one compound of formula I or a mixture or polymer comprising at least one compound of formula 1.

Definitions of Terms The term 'film' as used in this application includes self-supporting, i.e. free-standing, films that show more or less pronounced mechanical stability and flexibility, as well as coatings or layers on a supporting substrate or between two substrates.

( - 7 The term 'mesogenic compounds' as used in the foregoing and the following should denote compounds with a rod-shaped, lath-shaped or diskshaped mesogenic group, i.e. a group with the ability to induce mesophase behaviour. These compounds do not necessarily 5 have to exhibit mesophase behaviour by themselves. It is also possible that these compounds show mesophase behaviour only in mixtures with other compounds or when the mesogenic compounds or the mixtures comprising them are polymerized. Rodshaped and lath-shaped mesogenic groups are especially preferred.

For the sake of simplicity, the term 'liquid crystal material' is used hereinafter for both liquid crystal materials and mesogenic materials, and the term 'mesogen' is used for the mesogenic groups of the material.

15 O\ 0

The group -SO:- denotes a sulfonic group.

The groups-SO-O- and -O-SO- denote sulfinic acid ester groups O O 20 11 11

0 and 0, respectively.

Detailed Description of the Invention

The compounds of formula I are especially suitable for use in liquid crystalline polymerisable compositions where they lead to a high birefringence. They do not have to exhibit mesophase behaviour but show nesophase behaviour in mixtures with other compounds.

30 However, compounds of formula I with broad mesophases are; especially preferred.; When using tolanes to increase the birefringence in LO mixtures, one notable consequence is that the clearing point of the mixture usually 35 also increases. Whilst this is an advantage in most cases, in some situations it is desirable to control the clearing point without

- 8 significantly reducing the birefringence. It is therefore desirable to have compounds that lower the clearing point of polymerisable mesogenic mixtures. By using compounds of formula I it is possible to increase the birefringence without significantly changing the phase 5 transition temperatures of the mixture. Furthermore' the compounds of formula I show a tendency to suppress crystallization of the mixture. Another advantage of the compounds of formula I is that they have an advantageous effect on the polymerization process.

10 Particularly preferred are compounds of formula 1, wherein - R is -SR4, -S-CO-R', -CO-S-R', -SO2-R', -SO-O-R, or -O-SO-R', very preferably -SR', with R' being straight chain or branched, preferably straight chain alkyl with 1 to 20, preferably 1 to 12, very 15 preferably 1 to 8 C-atoms, - m1 =m2=0, - m1 +m2 is O or 1, preferably 0, - m1 is 1 end m2isO, 20 - m1 is O and m2 is 1, - A' and A2 are an aromatic group, preferably if m1 + m2 is O or 1, - Z' and Z2 are selected from -COO-, -OCO- and -C-C-, - rise, 25 - r is 1 or 2, - ris 1 or2 and L is F. - -Sp-X- is different from a single bond, - Sp is alkylene with 1 to 12 C atoms which is optionally mono- or 30 polysubstituted by F and wherein one or more non- adjacent CH2 may be replaced, in each case independently from one another, by-O-, -CH=CH- or-C-C-, - X is -O-, -COO-, -OCO-, -OCOO- or a single bond.

35 - Sp and X are a single bond,

( - 9 - L in formula I is preferably F, Cl, ON, OH, NO2, CH3, C2H5, OCHER, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2

or OC2F5, in particular F. Cl, ON, CH3, C2H5, OCH3, COCH3 or OCF3, most preferably F. Cl, CH3, OCH3 or COCH3.

A, and A2 in formula I are preferably an aromatic or alicyclic 5- or 6 ring, or a group comprising two or three fused aromatic or alicyclic 5 or 6-rings, wherein these rings may also contain one or more hetero atoms, in particular selected from N. O and S. and may also be 10 mono- or polysubstituted by L. Preferred groups A' and A2 in formula I are for example furan, pyrroi, thiophene, oxazole, thiazole, thiadiazole, imidazole, phenyiene, pyridine, pyrimidine, pyrazine, indane, naphthalene, 15 tetrahydronaphthalene, anthracene and phenanthrene.

Particularly preferably A' and A2 are selected from furane-2,5-dlyl, thiophene-2,5-dlyl, pyrrol-2,5-diyl, 1,4-phenylene, pyridine-2,5-dlyl, pyrimidine-2,5-dlyl, naphthalene-2,6-dlyl, 1,2,3,4-tetrahydro 20 naphthalene-2,6-dlyl, indane-2,5-diyl, furthermore 1,4-cyclohexylene in which, in addition, one or two non-adjacent CH2 groups may be replaced by O and/or S. it being possible for all these groups to be unsubstituted, mono- or polysubstituted by L as defined above.

25 Preferably the groups (Z,A')m, and (A2-Z2)m2 in formula I contain only monocyclic groups A, and A2, with m1 > m2. Very preferably the groups (A, Z,)m, and -(Z2-A2)m2- denote independently of each other a group with one or two five- or six-membered rings. The groups (AiZ4)m, and -(Z2-A2)m2may be identical or different.

30 Particularly preferred are compounds wherein (AiZ,)m and _(z2_ A2)m2are different.

Preferred subformulae for the groups (A4Z')m' and -(Z2-A2)m2- are listed below. For reasons of simplicity, Phe in these groups is 1,4 35 phenylene, Phe L is a 1,4-phenylene group which is substituted by 1 to 4 groups L as defined above, Pyd is pyridine-2,5-diyl and Pyr is

- 10 pyrimidine-2,5-diyl. The following list of preferred groups -(A1Z1) m1 and -(Z2-A2)m2- is comprising the subformulae 11-1 to 11-16 as well as their mirror images, which are linked via the radical Z to the tolane group in formula I -Phe-Z- 11-1 -Pyd-Z- 1 1-2 -Pyr-Z- 11-3 -PheL-Z- 114 10 -Phe-Z-Phe-Z- 11-5 -Phe-Z-Pyd-Z- I 1-6 -Pyd-Z-Phe-Z- 11-7 -Phe-Z-Pyr-Z11-8 -Pyr-Z-Phe-Z- I 1-9 15 -PheL-Z-Phe-Z- 11-10 PheL-Z-Pyd-Z- 11-1 1 PheL-Z-Pyr-Z- 11-1 2 -Pyr-Z-Pyd-Z- 11-1 3 -Pyd-Z-Pyd-Z- 11-1 4 20 -Pyr-ZPyr-Z- 11-15! -PheL-Z-PheL-Z- 11-16 In these preferred groups Z has the meaning of Z' as given in formula 1. Preferably Z is -COO-, -OCO-, CH2CH2 25 -C-C- or a single bond.: Very preferably-(A,-Z4)m,- and -(Z2-A2) m2- are, independently of each other, selected from the following formulae and their mirror images, which are linked via the radical Z to the tolane group in formula I: (L)r z!la

( Z- fib 3 kc lo, (L)r (L)r l 10 a_ z lid (L)r (L)r l 15 COO4Z He (L)r (L) r 20 - Z 1 If! wherein Z and L have the meaning given above and r is 0, 1, 2, 3 or I 4, preferably 0, 1 or 2.

25 (L),

The group in these preferred formulae is very preferably L L L L L

denoting or furthermore: 30 L with L having each independently one of the meanings given above.

Particularly preferred are the subformulae lla, llc, llf, kg and lih, in particular the sublormulae lla, lid and llf.

Especially preferred are compounds of formula I comprising at least

( - 12 - (L)r one group wherein r is 1.

5 Further preferred are compounds of formula I comprising at least (L)r two groups wherein r is 1 and/or at least one group (L)r 10 wherein r is 2.

If R in formula I is an alkylsulfanyl group, i.e. alkyl where the CH2 group that is linked to the adjacent group is replaced by -S-, this may be straight chain or branched. It is preferably straight chain, has 1, 2, 15 3, 4, 5, 6, 7 or 8 carbon atoms and accordingly is preferably methylsulfanyl, ethylsulfanyl, propylsulfanyl, butylsulfanyl, pentylsulfanyl, hexylsulfanyl, heptylsulfanyl, octylsulfanyl, furthermore nonylsulfanyl, decylsulfanyl, undecylsulfanyl or dodecylsulfanyl, for example.

If R is a thiocarboxyl or alkylsulfanylcarbonyl group, i.e. alkyl wherein the CH2 group that is linked to the neighboured group is replaced by -COS- or-S-CO-, this may be straight chain or branched. It is preferably straight chain, has 2, 3, 4, 5, 6, 7 or 8 carbon atoms and 25 accordingly is preferably thioacetyl, thiopropionyl, thiobutyryl, thiopentanoyl, thiohexanoyl, thioheptanoyl, thiooctanoyl, methylsulfanylcarbonyl, ethylsulfanylcarbonyl, propylsulfanylcarbonyi, butylsulfanylcarbonyl, pentylsulfanylcarbonyl, hexylsulfanylcarbonyl or heptylsulfanylcarbonyl.

If R is an alkylsulfonyl group, i.e. alkyl wherein the CH2 group that is neighboured to the adjacent group is replaced by a sulfonyl group SO2-, this may be straight chain or branched. It is preferably straight chain, has 1, 2, 3, 4, 5, 6, 7 or 8 carbon atoms and accordingly is 35 preferably methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, hexylsulfonyl, heptylsulfonyl or octylsulfonyl,

( - 13 furthermore nonylsulfonyl, decyisulfonyl, undecylsulfonyl or dodecylsulfonyl, for example.

If R is a sulfinic acid ester group (sulfinyloxyalkyl) or an alkyisulfinic 5 acid group (alkylsulfinyloxy), i.e. alkyl wherein the CH2 group that is neighboured to the adjacent group is replaced by -O-SO- or- SO-O-, this may be straight chain or branched. It is preferably straight chain, has 1, 2, 3, 4, 5, 6, 7 or 8 carbon atoms and accordingly is preferably sulfinyloxymethyl, sulfinyloxyethyl, sulfinyloxypropyl, sulfinyloxybutyl, 10 sulfinyloxypentyl, sulfinyloxyhexyl, sulfinyloxyheptyl or sulfinyloxyoctyl, furthermore methylsulfinyloxy, ethylsulfinyloxy, propylsulfinyloxy, butylsulfinyloxy, pentylsulfinyloxy, hexyisulfinyloxy, heptylsulfinyloxy or octylsulfinyloxy, for example.

15 In the compounds of formula I R may be an achiral or a chiral group.

In case of a chiral group it is preferably selected according to the following formula lil: -X1-Q1-CH-Q2

1 3 111

wherein 25 X' is -S-, -S-CO-, -CO-S-, -SO2-, -O2S- or a single bond, Q' is an alkylene or alkylene-oxy group with 1 to 10 C atoms or a single bond, 30 Q2 is an alkyl-or alkoxy group with 1 to 10 C atoms which may be unsubstituted, mono- or polysubstituted by halogen or CN, it being also possible for one or more non-adjacent CH2 groups to be replaced, in each case independently from one another, by -C-C-, -O-, -S-, -N H-, -N (CH3)-, -CO-, -COO-, -OCO-, -OCO-O-,

35 -S-CO- or -CO-S- in such a manner that oxygen atoms are not linked directly to one another,

( - 14 Q3 is halogen, a cyano group or an alkyl or alkoxy group with 1 to 4 C atoms different from Q2.

5 In case Q' in formula lil is an alkylene-oxy group, the O atom is preferably adjacent to the chiral C atom.

Preferred chiral groups R are 2-butylsulfanyl (=1 methylpropylsulfanyl), 2-methylbutylsulfanyl, 2-methylpentylsulfanyl, 10 3-methylpentylsulfanyl, 2-ethylhexylsulfanyl, 2-propylpentylsulfanyl, 2-octylsulfanyl, in particular 2-methylbutylsulfanyl, 4 methylpentylsulfanyl, 4methylhexylsulfanyl, 2-nonylsulfanyl, 2 decylsulfanyl, 2-dodecylsulfanyl, methyloctylsufanyl, 6 methylthiooctanoyl, 5-methylheptylsulfanylcarbonyl, 2 15 methylthiobutyryl, 3-methylthiovaleroyl, 4-methylthiohexanoyl, 2 chlorothiopropionyl, 2-chloro-3-methylthiobutyryl, 2-chloro-4 methylthiovaleryl, 2-chloro-3-methylthiovaleryl, 2-methyl-3 sulfanylpentyl, 2-methyl-3-sulfanylhexyl, 2-fluorooctylsulfanyl, 2 fluorodecylsulfanyl for example.

Halogen is preferably F or Cl.

The polymerisable or reactive group P is preferably selected from 25 CH2=cw, coo, W HC-CH-, W22(CH2)k-O CH2=CW2 ( )k1-, CH3-CH=CH-O-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, Ho-CW2W3-, HS CW2W3-, HW2N-, Ho-CW2W3-NH-, CH2=CW'-CO-NH-, CH2-CH 30 (COO) k,-Phe-(O)k2-, Phe-CH=CH-, HOOC-, OCN-, and W4W5W6Si-, with W' being H. Cl, CN, phenyl or alkyl with 1 to 5 C-atoms, in particular H. Cl or CH3, w2 and W3 being independently of each other H or alkyl with 1 to 5 Catoms, in particular methyl, ethyl or n propyl, W4, W5 and w6 being independently of each other Cl, 35 oxaalkyl or oxacarbonylalkyl with 1 to 5 C-atoms, Phe being 1,4 phenylene and k' and k2 being independently of each other 0 or 1.

( - 15 Especially preferably P is a vinyl group, an acrylate group, a methacrylate group, a propenyl ether group or an epoxy group, especially preferably an acrylate or a methacrylate group.

As for the spacer group Sp all groups can be used that are known for this purpose to those skilled in the art. The spacer group Sp is preferably a linear or branched alkylene group having 1 to 20 C atoms, in particular 1 to 12 C atoms, in which, in addition, one or 10 more non-adjacent CH2 groups may be replaced by -O-, -S-, -NH-, N(CH3)-, -CO-, -O-CO-, -S-CO-, O-COO-, -CO-S-, -CO-O-,

CH(halogen)-, -C(halogen)2, -CH(CN)-, -CH=CH- or -CaC-,or a siloxane group.

15 Typical spacer groups are for example -(CH2)p-, -(CH2CH2O)r-CH2CH2-, CH2CH2-S-CH2CH2- or-CH2CH2-NH-CH2CH2- or-(SiR R -O)p-, with p being an integer from 2 to 12, r being an integer from 1 to 3 and R and R having the meanings given in formula 1.

20 Preferred spacer groups are ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethylene-N-methyl iminoethylene, 1-methylalkylene, ethenylene, propenylene and 25 butenylene for example.

Further preferred are compounds with one or two groups P-Sp-X wherein Sp and/or X is a single bond.

30 In case of compounds with two groups P-Sp-X, each of the two polymerisable groups P. the two spacer groups Sp, and the two linkage groups X can be identical or different.

In another preferred embodiment of the invention the chiral 35 compounds of formula I comprise at least one spacer group Sp that is a chiral group of formula IV:

- 16 -Q -CH-Q

Q3 IV wherein Q' and Q3 have the meanings given in formula lil, and 10 Q4 is an alkylene or alkylene-oxy group with 1 to 10 C atoms or a single bond, being different from Q'.

Particularly preferred compounds of formula I are those of the following formulae (L)r (L)r P-Sp-XR 1 20 (L)r (L), (L)r P-Sp-X4 COOR lb 25 (L)r (L) . (L)r P-Sp-X R ic (L)r (L)r (L)r P-SXCH=CH-COO 4=: R Id (L)r (L)r (L)r 35 P-Sp-X4CH=CH WAR le

( - 17 wherein P. Sp, X, L, r and R have one of the meanings given above, R is especially preferably -S-R' as defined above, and the group (L)r has preferably one of the meanings given above.

The compounds of formula I can be synthesized according to or in analogy to methods which are known per se and which are described in standard works of organic chemistry such as, for example, 10 Houben-Weyl, Methoden der organischen Chemie, Thieme-Verlag, Stuttgart. Some specific methods of preparation can be taken from the examples.

The compounds of formula I can be used in a liquid crystal mixture 15 for displays like, for example, TN or STN displays, active matrix displays, displays of the IPS (in plane switching) or VA (vertically aligned) mode like VAN (vertically aligned nematic) or VAC (vertically aligned cholesteric), displays of the ECB (electrically controlled birefringence), DAP (deformation of aligned phases), CSH (colour 20 super homeotropic) or ASM (axially symmetric microcell) mode, phase-change, guest-host, flexoelectric, ferroelectric displays, bistable nematic and cholesteric displays like PSCT (polymer stabilized cholesteric texture), or PDLC, polymer gel or polymer network displays.

In particular, the polymerisable compounds of formula I and mixtures comprising them are useful for liquid crystal displays that comprise a polymer or polymer network component for the purpose of assisting alignment, mesophase stability and/or electrooptical property 30 improvement, in particular to achieve faster response times and/or lower threshold voltages, or for the purpose to create a multidomain structure to achieve improved contrast at wide viewing angles. Such displays are for example of the TN, STN, ECB, VA, IPS, multidomain or hybrid mode, and are described for example in US 5,189,540, US 35 6,177, 972, EP 0 903 392, and Hasebe et al., Jpn.J.Appl.Phys.1994, 33, 6245.

- - 18 Furthermore, the compounds of formula I are suitable as polymerisable component in active broadband polymer stabilized liquid crystal displays as described for example in H. Guillard and P. 5 Sixou, Liq. Cryst. (2001) 28(6), 933, the entire disclosure of which is

incorporated into this application by reference. These dispays comprise an active cholesteric layer with a broadened reflection wavelength band that is switchable between a planar reflective, a scattering and a homeotropic transparent state.

The compounds of formula I are also suitable as a polymer component in polymer stabilised displays, such as bistable PSCT (polymer stabilized cholesteric texture) displays, or PDLC or polymer gel displays of the scattering type. Anisotropic polymer gels and 15 displays comprising them are disclosed for example in DE 195 04 224, GB 2 279 659, WO 93/22397, US 5,538,768, US 5,543,075 and EP 0 451 905

Thus, another object of the invention is a liquid crystal mixture, in 20 particular a nematic liquid crystal mixture, comprising at least one compound of formula 1.

Yet another object of the invention is a liquid crystal display comprising a liquid crystal medium containing at least one compound 25 of formula 1.

For the applications described above the liquid crystal mixture preferably contains at least one compound of formula 1, and a nematic host mixture comprising one or more nematic or 30 nematogenic compounds.

Preferably the liquid crystal mixture consists of 2 to 25, preferably 3 to 15 compounds, at least one of which is a compound of formula 1.

The other compounds, forming the nematic host mixture, are 35 preferably low molecular weight liquid crystal compounds selected from nematic or nematogenic substances, for example from the

- 19 known classes of the azoxybenzenes, benzylidene-anilines, biphenyls, terphenyls, phenyl or cyclohexyl benzoates, phenyl or cyclohexyl esters of cyclohehexanecarboxylic acid, phenyl or cyclohexyl esters of cyclohexylbenzoic acid, phenyl or cyclohexyl 5 esters of cyclohexylcyclohexanecarboxylic acid, cyclohexylphenyl esters of benzoic acid, of cyclohexanecarboxylic acid and of cyclo hexylcyclohexanecarboxylic acid, phenylcyclohexanes, cyclohexyl biphenyls, phenylcyclohexylcyclohexanes, cyclohexylcyclohexanes, cyclohexylcyclohexenes, cyclohexylcyclohexylcyclohexenes, 1,4-bis- 9 10 cyclohexylbenzenes, 4,4'-bis-cyclohexylbiphenyls, phenyl- or cyclo hexylpyrimidines, phenyl- or cyclohexylpyridines, phenyl- or cyclo hexylpyridazines, phenyl- or cyclohexyidioxanes, phenyl- or cyclo hexyl-1, 3-dithianes, 1,2-diphenyl-ethanes, 1,2-dicyclohexylethanes, 1-phenyl-2cyclohexylethanes, 1-cyclohexyl-2-(4-phenylcyclohexyl) 15 ethanes, 1cyclohexyl-2-biphenyl-ethanes, 1-phenyl2-cyclohexyl phenylethanes,optionally halogenated stilbenes, benzyl phenyl ether, tolanes, substituted cinnamic acids and further classes of nematic or nematogenic substances. The 1,4-phenylene groups in these compounds may also be laterally mono- or difluorinated.

The liquid crystal mixture of this preferred embodiment is based on the achiral compounds of this type.

The most important compounds that are possible as components of 25 these liquid crystal mixtures can be characterized by the following formula R'L'-G'-E-R"

30 wherein L' and E, which may be identical or different, are in each case, independently from one another, a bivalent radical from the group formed by-Pine-, -Cyc-, -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -Pyr-, -Dio-, -BPhe- and -B-Cyc- and their mirror images, where Phe is unsubstituted or fluorine-substituted 1,4-phenylene, Cyc is trans 35 1,4-cyclohexylene or 1,4-cyclohexenylene, Pyr is pyrimidine-2,5-diyl or pyridine-2,5-diyl, Dio is 1,3-dioxane-2,5-diyl abd B is 2-(trans-1,4

( - 20 cyclohexyl)ethyl, pyrimidine-2,5-dlyl, pyridine-25-diyl or 1,3dioxane 2,5-dlyl. I G' in these compounds is selected from the following bivalent groups 5 CH=CH-,-N(0)N-,-CH=CY-,-CH=N(0)-,-C-C-,-CH2-CH2-,

-CO-O-, -CH2-O-, -CO-S-, -CH2-S-, -CH=N-, -COO-Phe-COO- or a: single bond, with Y being halogen, preferably chlorine, or -CN.

R' and R" are, in each case, independently of one another, alkyl, 10 alkenyl, alkoxy, alkenyloxy, alkanoyloxy, alkoxycarbonyl or alkoxycarbonyloxy with 1 to 18, preferably 3 to 12 C atoms, or alternatively one of R' and R" is F. CF3' OCF3, Cl, NCS or CN.

In most of these compounds R' and R" are, in each case, 15 independently of each another, alkyl, alkenyl or alkoxy with different chain length, wherein the sum of C atoms in nematic media generally is between 2 and 9, preferably between 2 and 7.

Many of these compounds or mixtures thereof are commercially: 20 available. All of these compounds are either known or can be prepared by methods which are known per se, as described in the literature (for example in the standard works such as Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), to be precise under reaction 25 conditions which are known and suitable for said reactions. Use may also be made here of variants which are known per se, but are not mentioned here.

The compounds of formula I and polymerisable liquicl crystal 30 mixtures comprising them are further useful for the preparation of anisotropic polymer films or coatings.

For the preparation of anisotropic polymer gels or polymer films, the liquid crystal mixture should comprise at least one polymerisable 35 compound, which can be a compound of formula I or an additional I polymerisable mesogenic or liquid crystalline compound.

( - 21 Examples of suitable polymerisable mesogenic compounds that can be used as comonomers together with the compounds of formula I in a polymerisable liquid crystal mixture, are disclosed for example in 5 WO 93/22397; EP 0,261,712; DE: 195,04,224; WO 95/22586 and WO 97/00600. The compounds disclosed in these documents, however, are to be regarded merely as examples that shall not limit the scope of this invention.

10 Preferably the polymerisable liquid crystal mixture comprises at least one polymerisable mesogenic compound having one polymerisable functional group and at least one polymerisable mesogenic compound having two or more polymerisable functional groups.

15 Examples of especially useful chiral and achiral polymerisable mesogenic compounds are shown in the following lists which should, however, be taken only as illustrative and is in no way intended to restrict, but instead to explain the present invention: P-(CH2)xO COO Y (Va) P-(CH2)XO COO MY

25 (Vb) P-(CH2)XO l COO I} R (Vc) P(CH2)xO COO R (Vd) 35 P-(CH2)XO CHCH-COO R (Ve)

( - 22 CH2=CHCOO(CH2)X O =l R V (Vf) P(CH2)xO R (F) (F) (F)

(Vg) 1 0 P-(CH2)XO COO 3 jig CH2CH(CH3)c2H5 L1 (Vh) P-(CH2)XO COO COO CH2CH(CH3)C2Hs (vi) P-(CH2)xO COO-Ter (Vk) 20 P-(CH2)xO COO-Cho' (Vm) P(CH2)XO COO I\

(Vn) P(CH2)XO COO OCO O(CH2)yP (Via) 30 L' L2

P(CH2)xo CH2CH2 CH2CH2 O(CH2)yP (Vlb) 35 P 03Co2602co - - p (Vlc)

( - 23 P(CH2)x CH=CHCOO: 5 OOCCH=CH o(CH2)yP P(CH2)XO A: O(CH2)yP wherein P has one of the meanings of formula I and its preferred 15 meanings as mentioned above, x and y are identical or different integers from 1 to 12, A and D are 1,4-phenylene or 1,4 cyclohexylene, v is 0 or 1, Y is a polar group, R is a non-polar alkyl or alkoxy group, Ter is a terpenoid radical like e.g. menthyl, Chol is a cholesterol group, and L' and L2 are each independently H. F. Cl, 20 OH, CN, NO2 or optionally alkyl, alkoxy, alkylcarbonyl or alkoxycarbonyl with 1 to 7 C atoms.

The term 'polar group' in this connection means a group selected from F. Cl, CN, NO2, OH, OCH3, OCN, SON, an optionally fluorinated 25 carbonyl or carboxyl group with up to 4 C atoms or a mono- oligo- or polyfluorinated alkyl or alkoxy group with 1 to 4 C atoms. The term 'non polar group' means an alkyl group with 1 or more, preferably 1 to 12 C atoms or an alkoxy group with 2 or more, preferably 2 to 12 C atoms.

30 The polymerisable liquid crystal mixtures according to the present invention may also comprise one or more non-reactive chiral dopants in addition or alternatively to chiral polymerisable mesogenic compounds. Typically used chiral dopants are e.g. the commercially available R or S 81 1, R or S 101 1, R or S 2011 or CB 15 (from Merck 35 KGaA, Darmstadt, Germany).

! - 24 Very preferred are chiral dopants with a high helical twisting power (HTP), in particular dopants comprising a sorbitol group as described in WO 98/00428, dopants comprising a hydrobenzoin group as described in GB 2,328,207, chiral binaphthyl derivatives as described 5 in WO 02/94805, chiral binaphthol acetal derivatives as described in WO 02/34739, chiral TADDOL derivatives as described in WO 02/06265, and chiral compounds having at least one fluorinated linkage group and a terminal or central chiral group as described in WO 02/06196 and WO 02/06195.

To prepare anisotropic polymer films, the polymerisable liquid crystal is preferably coated onto a substrate, aligned and polymerised in situ, for example by exposure to heat or actinic radiation, to fix the orientation of the liquid crystal molecules. Alignment and curing are 15 carried out in the liquid crystalline phase of the mixture.

The substrate is for example a glass or quartz sheet or a plastic film or sheet, and can be removed after polymerization or not. Suitable plastic substrates are for example polyethyleneterephthalate (PET), 20 of polyvinylalcohol (PVA), polycarbonate (PC) or triacetylcellulose (TAC). The polymerisable chiral LC material may also be dissolved or dispersed in an organic solvent that is evaporated before or during polymerization. 25 Alignment of the liquid crystal material can be achieved for example by treatment of the substrate onto which the material is coated, by shearing the material during or after coating, by application of a magnetic or electric field to the coated material, or by the addition of

surface-active compounds to the liquid crystal material. Reviews of 30 alignment techniques are given for example by 1. Sage in ]hermotropic Liquid Crystals., edited by G. W. Gray, John Wiley & Sons, 1987, pages 7577, and by T. Uchida and H. Seki in Liquid Crystals - Applications and Uses Vol. 3", edited by B. Bahadur, World Scientific Publishing, Singapore 1992, pages 1-63. A review of 35 alignment materials and techniques is given by J. Cognard, Mol. Cryst. Liq. Cryst. 78, Supplement 1 (1981), pages 1-77.

( - 25 Polymerisation takes place by exposure to heat or actinic radiation Actinic radiation means irradiation with light, like UV light, IR light or -

visible light, irradiation with X-rays or gamma rays or irradiation with 5 high energy particles, such as ions or electrons. Preferably polymerization is carried out by UV irradiation at a non-absorbing wavelength. As a source for actinic radiation for example a single UV lamp or a set of UV lamps can be used. When using a high lamp power the curing time can be reduced. Another possible source for 10 actinic radiation is a laser, like e.g. a UV laser, an IR laser or a visible laser. Polymerisation is carried out in the presence of an initiator absorbing at the wavelength of the actinic radiation. For example, when a 15 polymerising by means of UV light, a photoinitiator can be used that decomposes under UV irradiation to produce free radicals or ions that start the polymerization reaction. When curing polymerisable mesogens with acrylate or methacrylate groups, preferably a radical photoinitiator is used, when curing polymerisable mesogens vinyl and 20 epoxide groups, preferably a cationic photoinitiator is used. It is also possible to use a polymerization initiator that decomposes when heated to produce free radicals or ions that start the polymerization.

As a photoinitiator for radical polymerization for example the commercially available Irgacure 651, Irgacure 184, Darocure 1 173 or 25 Darocure 4205 (all from Ciba Geigy AG) can be used, whereas in case of cationic photopolymerisation the commercially available UVI 6974 (Union Carbide) can be used.

The polymerisable material can additionally comprise one or more other 30 suitable components such as, for example, catalysts, sensitizers, stabilizers, inhibitors, antioxidants, chain-transfer agents, co-reacting monomers, surface-active compounds, lubricating agents, wetting agents, dispersing agents, hydrophobing agents, adhesive agents, flow improvers, defoaming agents, deaerators, diluents, reactive diluents, 35 auxiliaries, colourants, dyes or pigments.

- 26 Compounds of formula I comprising a chiral group are suitable as chiral dopants. Furthermore, the compounds of formula I are suitable as comonomers 2 5 for liquid crystal materials with semiconductor or charge carrier properties, which can be used in electronic devices like for example field r

effect transistors (PET) as components of integrated circuitry, as thin flim transistors in flat panel display applications or for Radio Frequency Identification (RFID) tags, or semiconducting components for organic 10 light emitting diode (OLED) applications such as electroluminescent displays or backlights of e.g. liquid crystal displays, photovoltaic or sensor devices, photoconductors, or electrophotographic applications like electrophotographic recording devices.

15 For example, semiconductors comprising polymerisable liquid crystal compounds are disclosed in WO 00/79617, JP-A-2000-347432, JP-A 1 1-209761, Sirringhaus et al., Appl. Phys. Lett., 77(3) (2000) 40608,,; and Grell et al., J. Korean Phys. Soc. 2000, 36(6), 331.

Electroluminescent devices using liquid crystal materials are described 20 for example in WO 95/17018 and WO 95/04306. Organic photoconductors with liquid crystal properties are described for example in EP 0 563 768 and EP 0 527 376. i Without further elaboration, it is believed that one skilled in the art 25 can, using the preceding description, utilize the present invention to

ist fullest extent. The following examples are, therefore, to be I construed as merely illustrative and not limitative of the remainder of the disclosure in any way whatsoever.

30 In the foregoing and in the following examples, unless otherwise indicated, all temperatures are set forth uncorrected in degrees Celsius and all parts and percentages are by weight.

The following abbreviations are used to illustrate the liquid crystalline 35 phase behaviour of the compounds: K = crystalline; N = nematic; S = smectic; Ch = cholesteric; I = isotropic. The numbers between the

( - 27 symbols indicate the phase transition temperatures in C. Furthermore, mp. is the melting point, An is the optical anisotropy i measured at 20 C and 589 nm, ME iS the dielectric anisotropy at 20 C and 1 kHz.

Example 1:

Compound (1) is prepared acording to the following reaction scheme 10 OH + Br'OH / Br + OH 1 K2CO3 1 Pd(PPh3)zCI2 1 Butanone NEt3 OH + CICI /S OH

NEt3 NaH DCM Toluene TWO jOC /5; 25 1 Pi(PPh:C I Cul I NEt3 THF o /SOo (1) Compound (1) has mp. = 108 CC and An = 0.31.!

- 28 Example 2

Compound (2) is prepared in analogy to example 1. I /so'o 0 10 (I)

Compound (2) has the phase sequence K 112 N 220 1 and n=0.35.

Claims (9)

1. - 29 Clalms 1. pOlymerisable compound of formula I 5 (L)r (L)r P-SP-X-(A -

   Z)m14=3(Z2 A2) R 1 0 wherein P is a polymerisable group, Sp is a spacer group or a single bond, 15 O

   X is -O-, -S-, -CO-, -COO-, -OCO-, -CH CH-, -OCO O-,-S-CO-,-CO-S-,-CO-NR ,-NR -CO-,-OCH2-,

   - CH2O-,-SCH2-,-CHzS-,-CH=CH-COO-,-OOC 20 CH=CH-, CH2CH2 or a single bond, Z. and Z2 are each independently -COO-, -OCO-, -CH2CH2-, -OCH2-, -CH2O-, -SCH=, -CH2S-, -CF2O-, -OCF;2-.

   -CF2S-, -SCF2-, -CH2CH2-, -CF2CH2-, -CH2CF2-,

   -CF2CF2-, -CH=CH-, -CH=CH-, -CF=CH-, -CH=CF-,

   25 -CF=CF-, -CH=CH-COO-, -OCO-C H=CH-, -C_C- or a single bond, A' and A2 are each independently an aliphatic or aromatic carbocyclic or heterocyclic group with up to 16 C 30 atoms that may also comprise fused rings and may be unsubstituted, mono- or polysubstituted with L, m1 and m2 are each independently 0, 1 or 2, with m1+m2 c 4, 35 R is straight chain or branched alkyl with up to 25 C atoms, which may be unsubstituted, monoor

   - 30 polysubstituted by F, Cl, Br, I or ON, it being also possible for one or more non-adjacent CH2 groups to be replaced, in each case independently from one another, by-O-, IS-, -NH-, -NR -, -SiR R -,-CO-, 5 -COO-, -OCC)-, -OCO-O-, -S-CO-, -CO-S-, -SO;r. -SO 0-, -O-SO-, -CH=CH- or -C=Cin such a manner that O and/or S atoms are not linked directly to one another, with the proviso that one or more CH2 groups are 10 replaced, in each case independently from one another, by-S-, -S-CO-, - CO-S-, -SO2-, -O2S-, -SO-O- or-O-SO-, R and R are independently of each other H or alkyl with 1 to 4 C atoms, L is id, Cl, Br, I, ON, NO2 or alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkylcarbonlyoxy with 1 to 7 C atoms, wherein one or more H atoms may be substituted by F or Cl, and r is 0, 1, 2, 3 or 4.
2. 2. A polymerisable compound as claimed in claim 1, wherein R is -S-R', SCO-R', -CO-S-R', -SO2-R', -SO-O-R, or-O-SO-R', wherein R' is 25 straight chain or branched alkyl with 1 to 20 C-atoms.
3. 3. polymerisable compound as claimed in claim 1 or claim 2, wherein m1 m2 is 0 or 1.
4. 4. A polymerisable compound as claimed in any one of claims 1 to 3, wherein A' and A2 are selected from furane-2,5-diyl, thiophene-2,5-diyl, pyrrol-2,5-diyl, 1,4-phenylene, pyridine-2,5-diyl, pyrimidine-2,5-diyl, naphthalene-2,6-diyl, 1,2,3,4-tetrahydro-naphthalene-2,6-diyl, indane-2, 5-diyl, and 1,4-cyclohexylene in which, in addition, one or two non 35 adjacent

   ( - 31

   CH2 groups may be replaced by O and/or S. it being possible for all these groups to be unsubstituted, mono- or polysubstituted by L as defined in formula 1.
5. 5 5. A polymerisable compound as claimed in any one of claims 1 to 4, characterized in that-(A'-Z')m'-and-(Z2-A2)m2-are, independently of each other, selected from the following formulae and their mirror images, which are linked via the radical Z to the tolane group in formula (L), 3 fib N 20 I</ 3z kc N (L)r (L)r 25 z lid (L)r (L), 30 COOK- lie (L3r (Lf) , _ LIZ- llf

   - 32 wherein L and r have the meanings of formula I and Z has one of the meanings Of Z' in formula 1.
6. 6 A polymerisable compound as claimed in any one of claims 1 to 5, 5selected from the following formulae (L)r (L)r P-SXR la (L)r (L), (L), PSp-X:COO:=4 R lb 5 (L), (or (L).

   P-Sp-X / R IC 20 wherein P. Sp, X, L, r and R have the meanings of formula 1.
7. 7, A polymerisable compound substantially as hereinbefore described in the foregoing examples.
8. 8. A polymerisable liquid crystal mixture comprising at least one compound as 25 claimed in any one of claims 1 to 7.

   9, An anisotropic polymer or polymer film obtained from a polymerisable liquid crystal mixture as claimed in claim 8.

   at 10. Use of a polymerisable liquid crystal material as claimed in any one of claims 1 to 7, a mixture as claimed in claim 8 or a polymer or polymer film as claimed: in claim 9 in optical films, polarisers, compensators beam splitters, reflective films, alignment layers, colour filters, holographic elements, hot stamping foils, 35 coloured imagers, decorative or security markings, liquid crystal pigments, adhesives, synthetic resins with anisotropic mechanical properties, cosmetics, diagnostics, nonlinear optics, optical information storage, as chiral dopants, in electronic devices like

   ! - 33 for example field effect transistors (FET) as components of

   integrated circuitry, as thin film transistors in flat panel display applications or for Radio Frequency Identification (RFID) tags, or in semiconducting components for organic light emitting diode 5 (OLED) applications such as electroluminescent displays or backlights of e.g. liquid crystal displays, for photovoltaic or sensor devices, as electrode materials in batteries, as photoconductors, or for electrophotographic applications like electrophotographic recording. 11. A liquid crystal display comprising in its active layer at least one compound as claimed in any one of claims 1 to 7, a mixture as claimed in claim 8 or a polymer or polymer film as claimed in claim
9. 9.