Mesogenic media and liquid crystal display

Abstract

Mesogenic media comprising a first component, component A, consisting of bimesogenic compounds optionally a second component, component B, consisting of nematogenic compounds, and optionally a second or third component, component C, consisting of one or more chiral molecules, is suitable for use in flexoelectric liquid crystal devices.

Claims

1. A mesogenic medium comprising: a first component, component A, consisting of bimesogenic compounds and comprising one or more compounds of formula A-0 and one or more compounds selected from formulae A-I to A-III ##STR00199## wherein R.sup.01 and R.sup.02 are each independently H, F, Cl, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms which may be unsubstituted, mono- or polysubstituted by halogen or CN, and wherein one or more non-adjacent CH.sub.2 groups, in each occurrence independently from one another, are optionally replaced by O, S, NH, N(CH.sub.3), CO, COO, OCO, OCOO, SCO, COS, CHCH, CHCF, CFCF or CC in such a manner that oxygen atoms are not linked directly to one another, MG.sup.01 is -A.sup.01-Z.sup.01-A.sup.02-, MG.sup.02 is -A.sup.03-Z.sup.02-A.sup.04-Z.sup.03-A.sup.05-, Z.sup.01 to Z.sup.03 are, independently of each other in each occurrence, a single bond, COO, OCO, OCOO, OCH.sub.2, CH.sub.2O, OCF.sub.2, CF.sub.2O, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, CF.sub.2CF.sub.2, CHCH, CFCF, CHCHCOO, OCOCHCH or CC, optionally substituted with one or more of F, S and/or Si, A.sup.01 to A.sup.05 are each independently in each occurrence 1,4-phenylene, wherein in addition one or more CH groups may each be replaced by N, trans-1,4-cyclo-hexylene in which, in addition, one or two non-adjacent CH.sub.2 groups may each be replaced by O or S, 1,4-cyclohexenylene, 1,4-bicyclo-(2,2,2)-octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydro-naphthalene-2,6-diyl, 1,2,3,4-tetrahydro-naphthalene-2,6-diyl, cyclobutane-1,3-diyl, spiro[3.3]heptane-2,6-diyl or dispiro[3.1.3.1]decane-2,8-diyl, wherein each of these groups is unsubstituted or mono-, di-, tri- or tetrasubstituted by substituents selected from F, Cl, CN, and alkyl, alkoxy, alkylcarbonyl and alkoxycarbonyl groups with 1 to 7 C atoms, wherein one or more H atoms may each be substituted by F or Cl, Sp.sup.0 is a spacer group comprising 1, 3 or 5 to 40 C atoms, wherein one or more non-adjacent and non-terminal CH.sub.2 groups may each be replaced by O, S, NH, N(CH.sub.3), CO, OCO, SCO, OCOO, COS, COO, CH(halogen)-, CH(CN), CHCH or CC, however in such a way that no two O-atoms are adjacent to one another, no two CHCH groups are adjacent to each other, and no two groups selected from OCO, SCO, OCOO, COS, COO and CHCH are adjacent to each other, and X.sup.01 and X.sup.02 are independently from one another a linking group selected from COO, OCO, CHCH, CC, O, SCO, COS, S and CO or a single bond, and wherein X.sup.01 and X.sup.02 are different from each other, however under the condition that in X.sup.01-Sp.sup.0-X.sup.02 no two O-atoms are adjacent to one another, no two CHCH groups are adjacent to each other, and no two groups selected from OCO, SCO, OCOO, COS, COO and CHCH are adjacent to each other, ##STR00200## wherein R.sup.11 and R.sup.12, R.sup.21 and R.sup.22 and R.sup.31 and R.sup.32 are each independently H, F, Cl, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms which may be unsubstituted, mono- or polysubstituted by halogen or CN, wherein one or more non-adjacent CH.sub.2 groups, in each occurrence independently from one another, are optionally replaced by O, S, NH, N(CH.sub.3), CO, COO, OCO, OCOO, SCO, COS, CHCH, CHCF, CFCF or CC in such a manner that oxygen atoms are not linked directly to one another, MG.sup.11 and MG.sup.12, MG.sup.21 and MG.sup.22 and MG.sup.31 and MG.sup.32 are each independently a mesogenic group, Sp.sup.1, Sp.sup.2 and Sp.sup.3 are each independently a spacer group comprising 5 to 40 C atoms, wherein one or more non-adjacent CH.sub.2 groups, with the exception of the CH.sub.2 groups of Sp.sup.1 linked to O-MG.sup.11 and/or O-MG.sup.12, of Sp.sup.2 linked to MG.sup.21 and/or MG.sup.22 and of Sp.sup.3 linked to X.sup.31 and X.sup.32, may each be replaced by O, S, NH, N(CH.sub.3), CO, OCO, SCO, OCOO, COS, COO, CH(halogen)-, CH(CN), CHCH or CC, however in such a way that (in the molecules) no two O-atoms are adjacent to one another, no two CHCH groups are adjacent to each other, and no two groups selected from OCO, SCO, OCOO, COS, COO and CHCH are adjacent to each other, and X.sup.31 and X.sup.32 are independently from one another a linking group selected from COO, OCO, CHCH, CC or S, and, alternatively, one of X.sup.31 and X.sup.32 may also be either O or a single bond, and, again alternatively, one of X.sup.31 and X.sup.32 may be O and the other one a single bond, an optional second component, component B, consisting of nematogenic compounds, and an optional second or third component, component C, consisting of one or more chiral molecules.

2. The mesogenic medium according to claim 1, wherein in said formulae A-I to A-III, MG.sup.11 and MG.sup.12, MG.sup.21 and MG.sup.22 and MG.sup.31 and MG.sup.32 are independently of each other selected from formula II
-A.sup.1-(Z.sup.1-A.sup.2).sub.m-II wherein Z.sup.1 is COO, OCO, OCOO, OCH.sub.2, CH.sub.2O, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, CF.sub.2CF.sub.2, CHCH, CFCF, CHCHCOO, OCOCHCH, CC or a single bond, A.sup.1 and A.sup.2 are each independently in each occurrence 1,4-phenylene, wherein in addition one or more CH groups may each be replaced by N, trans-1,4-cyclohexylene in which, in addition, one or two non-adjacent CH.sub.2 groups may each be replaced by O or S, 1,4-cyclohexenylene, 1,4-bicyclo-(2,2,2)-octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydro-naphthalene-2,6-diyl, 1,2,3,4-tetrahydro-naphthalene-2,6-diyl, cyclobutane-1,3-diyl, spiro[3.3]heptane-2,6-diyl or dispiro[3.1.3.1]decane-2,8-diyl, wherein each of these groups is unsubstituted or mono-, di-, tri- or tetrasubstituted by substituents selected from F, Cl, CN, and alkyl, alkoxy, alkylcarbonyl and alkoxycarbonyl groups with 1 to 7 C atoms, wherein one or more H atoms may each be substituted by F or Cl, and m is 0, 1, 2 or 3.

3. The mesogenic medium according to claim 1, wherein in formulae A-I to A-III, MG.sup.11 and MG.sup.12, MG.sup.21 and MG.sup.22 and MG.sup.31 and MG.sup.32 are each and independently selected from the following formulae and their mirror images ##STR00201## ##STR00202## wherein L is in each occurrence independently of each other F, Cl, CN, OH, NO.sub.2 or an optionally fluorinated alkyl, alkoxy or alkanoyl group with 1 to 7 C atoms, and r is in each occurrence independently of each other 0, 1, 2, 3 or 4.

4. The mesogenic medium according claim 1, wherein said medium comprises component B, and component B comprises one or more compounds selected from the group of compounds of formulae B-I to B-III: ##STR00203## wherein R.sup.B1, R.sup.B21 and R.sup.B22 and R.sup.B31 and R.sup.B32 are each independently H, F, Cl, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms which may be unsubstituted, mono- or polysubstituted by halogen or CN, wherein one or more non-adjacent CH.sub.2 groups, in each occurrence independently from one another, are optionally replaced by O, S, NH, N(CH.sub.3), CO, COO, COO, OCOO, SCO, COS, CHCH, CHCF, CFCF or CC in such a manner that oxygen atoms are not linked directly to one another, X.sup.B1 is F, Cl, CN, NCS, preferably CN, Z.sup.B1, Z.sup.B2 and Z.sup.B3 are in each occurrence independently CH.sub.2CH.sub.2, COO, OCO, CF.sub.2O, O CF.sub.2, CHCH or a single bond, ##STR00204## are in each occurrence independently ##STR00205## alternatively one or more of ##STR00206## are ##STR00207## and n is 1, 2 or 3.

5. The mesogenic medium according to claim 1, wherein said medium comprises one or more compounds of formula A-II.

6. The mesogenic medium according to claim 1, wherein said medium comprises one or more compounds of formula A-III.

7. The mesogenic medium according claim 4, wherein said medium comprises one or more compounds of formula B-I.

8. The mesogenic medium according to claim 4, wherein said medium comprises one or more compounds of formula B-II.

9. The mesogenic medium according to claim 4, wherein said medium comprises one or more compounds of formula B-III.

10. The mesogenic medium according to claim 4, wherein component B consists of compounds selected from the group of compounds of formulae B-I to B-III in a concentration of 40% or less based on the medium as a whole.

11. The mesogenic medium according to claim 1, wherein said medium exhibits a first nematic phase and a second nematic phase.

12. A method of generating an electro-optical effect comprising applying a voltage across a liquid crystal cell in a liquid crystal device, wherein said cell contains a mesogenic medium according to claim 1.

13. A liquid crystal device comprising a mesogenic medium according to claim 1.

14. The liquid crystal device according to claim 13, wherein said device is a flexoelectric device.

15. The liquid crystal device according to claim 13, wherein said device comprises two plane parallel electrodes the inner surfaces of which exhibit planar, anti-parallel alignment conditions.

16. The mesogenic medium according to claim 1, wherein said medium comprises one or more compounds of formula A-I.

17. The mesogenic medium according to claim 1, wherein Z.sup.01 to Z.sup.03 are each a single bond.

18. The mesogenic medium according to claim 1, wherein R.sup.01 and R.sup.02 are each independently F, Cl, CN, OCF.sub.3, or CF.sub.3.

19. The mesogenic medium according to claim 1, wherein A.sup.01 to A.sup.05 are each unsubstituted or mono-, di-, tri- or tetrasubstituted by substituents selected from F, Cl, CH.sub.3 and CF.sub.3.

20. The mesogenic medium according to claim 1, wherein Sp.sup.0 is (CH.sub.2).sub.n wherein n is an integer from 3 to 19.

21. The mesogenic medium according to claim 1, wherein Sp.sup.0 is (CH.sub.2).sub.n wherein n is 3, 5, 7, 9 or 11.

22. The mesogenic medium according to claim 1, wherein: (a) X.sup.01 is COO or O and X.sup.02 is a single bond, or (b) X.sup.01 is COO and X.sup.02 is O.

23. The mesogenic medium according to claim 1, wherein X.sup.01 is COO and X.sup.02 is a single bond.

24. The mesogenic medium according to claim 4, wherein X.sup.B1 is CN.

25. The mesogenic medium according to claim 1, wherein: the compounds of formula A-I are selected from the group of compounds of formulae A-I-1 to A-I-3 ##STR00208## wherein n is an integer from 3 to 19; the compounds of formula A-II are selected from the group of compounds of formulae A-II-1 to A-II-4 ##STR00209## wherein n is an integer from 3 to 19; and the compounds of formula A-III are selected from the group of compounds of formulae A-III-1 to A-III-11 ##STR00210## ##STR00211## wherein n is an integer from 3 to 19.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates the use of the flexoelectric 2 mode in a liquid crystal display; and

(2) FIG. 2 illustrates the use of the flexoelectric mode in a liquid crystal display.

(3) The main difference between the mode (illustrated in FIG. 2) and the 2 mode (shown in FIG. 1) is that the optical axis of the liquid crystal in the state at zero field is either parallel to one of the polariser axis (in the case of the 2 mode) or at an angle of 22.5 to axis one of the polarisers (in the case of the mode). The advantage of the 2 mode over the mode is that the liquid crystal display appears black when there is no field applied to the cell. The advantage of the mode, however, is that e/K may be lower because only half of the switching angle is required for this mode compared to the 2 mode.

(4) Comparing the switching speed of ULH mixtures it is important to also know the switching angle associated with the respective effect.

(5) The other mixture variables should also be considered. Higher temperature usually leads to faster switching times, usually because the viscosity of the mixture decreases. The field used is also important. Faster switching speed can usually be achieved with higher fields in ULH flexoelectric mode.

(6) Yet another factor which has to be considered are the details of the switching mode. Contrary to most commercial LC mode, the ULH T.sub.off time can be driven, therefore there are at least two possible switching regimes:
Switching time=T.sub.on+T.sub.off(driven)
Switching time=T.sub.on+T.sub.off(non-driven)

(7) If both switching on and switching off are driven the response times are much shorter, typically in the range of 2 ms compared to 5 ms.

(8) The present invention allows to reduce the switching times in both of these regimes by adding additives having a low rotational viscosity.

(9) As already mentioned above the present invention discloses a method of improving the switching speed of chiral flexo mixtures. It has been reported in the literature that the relaxation switching time of such mixtures can be described by the following equation

(10) $=\frac{}{K}\frac{p^2}{.Math.4{}^2},$

(11) Where is the effective viscosity associated with the distortion of the helix (Coles et al 2006). Furthermore in a paper from Coles et al. (B Musgrave, P. Lehmann, H. J. Coles, Liquid Crystals, (1999), 28 (8), 1235) the viscosity term is referred to as .sub.1.

(12) E.g. in J. Appl. Phys. 99, 034104 (2006) it is shown that the switching speed of a mixture of bimesogens mixture increases significantly with decreasing temperature. Though this can be counteracted to a certain degree by increasing the field applied the switching speed is still longer at lower temperature compared to higher temperatures.

(13) This invention shows that the addition of viscosity modifiers can improve the switching speed of mixtures containing dimers. Surprisingly even a small amount of a viscosity modifier can have a very large effect on the speed of switching. In addition the use of these compounds also lowers the temperature of the nematic to second nematic (twist bend) phase or other phases and reduces melting points and may also be used to increase the clearing point of the mixture.

(14) Liquid crystalline media comprising both bimesogens and nematogens are disclosed in GB 2 387 603. However these media have relatively low values of the flexoelectric ratio e/K.

(15) Other aims of the present invention are immediately evident to the person skilled in the art from the following detailed description.

(16) The inventors have found out that the above aims can be surprisingly achieved by providing bimesogenic compounds according to the present invention. These compounds, when used in chiral nematic liquid crystal mixtures, lead to low melting points, broad chiral nematic phases. In particular, they exhibit relatively high values of the elastic constant k.sub.11, low values of the bend elastic constant k.sub.33 and high values of the flexoelectric coefficient.

(17) The present invention relates to mesogenic materials comprising

(18) a first component, component A, consisting of bimesogenic compounds and comprising one or more compounds of formula A-0 and one or more compounds selected from the group of compounds of formulae A-I to A-III, from which the compounds of formula A-0 are excluded,

(19) ##STR00002## wherein R.sup.01 and R.sup.02 are each independently H, F, Cl, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms which may be unsubstituted, mono- or polysubstituted by halogen or CN, it being also possible for one or more non-adjacent CH.sub.2 groups to be replaced, in each occurrence independently from one another, by O, S, NH, N(CH.sub.3), CO, COO, OCO, OCOO, SCO, COS, CHCH, CHCF, CFCF or CC in such a manner that oxygen atoms are not linked directly to one another, preferably a polar group, more preferably F, Cl, CN, OCF.sub.3, CF.sub.3, MG.sup.01 is -A.sup.01-Z.sup.01-A.sup.02-, MG.sup.02 is -A.sup.03-Z.sup.02-A.sup.04-Z.sup.03-A.sup.05-, Z.sup.01 to Z.sup.03 are, independently of each other in each occurrence, a single bond, COO, OCO, OCOO, OCH.sub.2, CH.sub.2O, OCF.sub.2, CF.sub.2O, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, CF.sub.2CF.sub.2, CHCH, CFCF, CHCHCOO, OCOCHCH or CC, optionally substituted with one or more of F, S and/or Si, preferably a single bond, A.sup.01 to A.sup.05 are each independently in each occurrence 1,4-phenylene, wherein in addition one or more CH groups may be replaced by N, trans-1,4-cyclo-hexylene in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by O and/or S, 1,4-cyclohexenylene, 1,4-bicyclo-(2,2,2)-octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydro-naphthalene-2,6-diyl, 1,2,3,4-tetrahydro-naphthalene-2,6-diyl, cyclobutane-1,3-diyl, spiro[3.3]heptane-2,6-diyl or dispiro[3.1.3.1]decane-2,8-diyl, it being possible for all these groups to be unsubstituted, mono-, di-, tri- or tetrasubstituted with F, Cl, CN or alkyl, alkoxy, alkylcarbonyl or alkoxycarbonyl groups with 1 to 7 C atoms, wherein one or more H atoms may be substituted by F or Cl, preferably F, Cl, CH.sub.3 or CF.sub.3, Sp.sup.0 is a spacer group comprising 1, 3 or 5 to 40 C atoms, wherein one or more non-adjacent and non-terminal CH.sub.2 groups may also be replaced by O, S, NH, N(CH.sub.3), CO, OCO, SCO, OCOO, COS, COO, CH(halogen)-, CH(CN), CHCH or CC, however in such a way that no two O-atoms are adjacent to one another, now two CHCH groups are adjacent to each other and no two groups selected from OCO, SCO, OCOO, COS, COO and CHCH are adjacent to each other, preferably CH.sub.2).sub.n (i.e. 1,n-alkylene with n C atoms), with n an integer, preferably from 3 to 19, more preferably from 3 to 11, most preferably an odd integer (i.e. 3, 5, 7, 9 or 11), X.sup.01 and X.sup.02 are independently from one another a linking group selected from COO, OCO, CHCH, CC, O, SCO, COS, S and CO or a single bond, preferably they are different from each another and preferably X.sup.01 is COO or O and X.sup.02 is a single bond or X.sup.01 is COO and X.sup.02 is O, most preferably X.sup.01 is COO and X.sup.02 is a single bond,
however under the condition that in X.sup.01-Sp.sup.0-X.sup.02 no two O-atoms are adjacent to one another, now two CHCH groups are adjacent to each other and no two groups selected from OCO, SCO, OCOO, COS, COO and CHCH are adjacent to each other.

(20) ##STR00003## wherein R.sup.11 and R.sup.12, R.sup.21 and R.sup.22 and R.sup.31 and R.sup.32 are each independently H, F, Cl, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms which may be unsubstituted, mono- or polysubstituted by halogen or CN, it being also possible for one or more non-adjacent CH.sub.2 groups to be replaced, in each occurrence independently from one another, by O, S, NH, N(CH.sub.3), CO, COO, OCO, OCOO, SCO, COS, CHCH, CHCF, CFCF or CC in such a manner that oxygen atoms are not linked directly to one another, MG.sup.11 and MG.sup.12, MG.sup.21 and MG.sup.22 and MG.sup.31 and MG.sup.32 are each independently a mesogenic group, Sp.sup.1, Sp.sup.2 and Sp.sup.3 are each independently a spacer group comprising 5 to 40 C atoms, wherein one or more non-adjacent CH.sub.2 groups, with the exception of the CH.sub.2 groups of Sp.sup.1 linked to O-MG.sup.11 and/or O-MG.sup.12, of Sp.sup.2 linked to MG.sup.21 and/or MG.sup.22 and of Sp.sup.3 linked to X.sup.31 and X.sup.32, may also be replaced by O, S, NH, N(CH.sub.3), CO, OCO, SCO, OCOO, COS, COO, CH(halogen)-, CH(CN), CHCH or CC, however in such a way that (in the molecules) no two O-atoms are adjacent to one another, no two CHCH groups are adjacent to each other, and no two groups selected from OCO, SCO, OCOO, COS, COO and CHCH are adjacent to each other and X.sup.31 and X.sup.32 are independently from one another a linking group selected from COO, OCO, CHCH, CC or S, and, alternatively, one of them may also be either O or a single bond, and, again alternatively, one of them may be O and the other one a single bond,
optionally, preferably obligatorily a second component, component B, consisting of nematogenic compounds, preferably selected from the group of compounds of formulae B-I to B-III

(21) ##STR00004## wherein R.sup.B1, R.sup.B21 and R.sup.B22 and R.sup.B31 and R.sup.B32 are each independently H, F, Cl, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms which may be unsubstituted, mono- or polysubstituted by halogen or CN, it being also possible for one or more non-adjacent CH.sub.2 groups to be replaced, in each occurrence independently from one another, by O, S, NH, N(CH.sub.3), CO, COO, OCO, OCOO, SCO, COS, CHCH, CHCF, CFCF or CC in such a manner that oxygen atoms are not linked directly to one another, X.sup.B1 is F, Cl, CN, NCS, preferably CN, Z.sup.B1, Z.sup.B2 and Z.sup.B3 are in each occurrence independently CH.sub.2CH.sub.2, COO, OCO, CF.sub.2O, OCF.sub.2, CHCH or a single bond, preferably CH.sub.2CH.sub.2, COO, CHCH or a single bond, more preferably CH.sub.2CH.sub.2 or a single bond, even more preferably one of the groups present in one compound is CH.sub.2CH.sub.2 and the others are a single bond, most preferably all are a single bond,

(22) ##STR00005##
are in each occurrence independently

(23) ##STR00006## preferably

(24) ##STR00007## most preferably

(25) ##STR00008##
alternatively one or more of

(26) ##STR00009##
are

(27) ##STR00010##
and
n is 1, 2 or 3, preferably 1 or 2,
and
a optionally, preferably obligatorily, a second or third component, component C, consisting of one or more chiral molecules.

(28) Preferred according to the present application are compounds of formula I wherein the linking groups X.sup.01 and X.sup.02 are different from each other, preferably one is OCO or COO and the other O or a single bond, preferably a single bond, preferably X.sup.01-Sp.sup.0-X.sup.02 is OCO-Sp.sup.0-O, O-Sp.sup.0-COO, OCO-Sp.sup.0-, -Sp.sup.0-COO, -Sp.sup.0-O or O-Sp.sup.0-, more preferably OCO-Sp.sup.0-, -Sp.sup.0-COO, -Sp.sup.0-O or O-Sp.sup.0- and most preferably OCO-Sp.sup.0- or -Sp.sup.0-COO, Sp.sup.0 preferably is (CH.sub.2).sub.n with n preferably 1, 3, 4 or an integer from 5 to 15, more preferably 4, 5, 6, 7, 8 or 9, in case of X.sup.01 and X.sup.02 in X.sup.01-Sp.sup.0-X.sup.02 having one or three atoms contributing to the distance between the mesogenic groups MG.sup.01 and MG.sup.02, e.g. X.sup.01-Sp.sup.0-X.sup.02 is O-Sp.sup.0-, -Sp.sup.0-O, S-Sp.sup.0-, -Sp.sup.0-S, COO-Sp.sup.0-O or O-Sp.sup.0-COO, n preferably is even and most preferably is 4, 6 or 8, whereas in case of X.sup.01 and X.sup.02 in X.sup.01-Sp.sup.0-X.sup.02 having two or four atoms contributing to the distance between the mesogenic groups MG.sup.01 and MG.sup.02, e.g. X.sup.01-Sp.sup.0-X.sup.02 is O-Sp.sup.0-S, O-Sp.sup.0-S, COO-Sp.sup.0- or COS-Sp.sup.1-OCO, n preferably is odd and most preferably is 5, 7 or 9,
wherein one or more H atoms in (CH.sub.2).sub.n may independently of each other optionally be replaced by F or CH.sub.3.

(29) Further preferred according to the present application are compounds of formula I as defined above, wherein additionally or alternatively to any of the previous preferred conditions the end groups R.sup.01 and R.sup.02 are different from each other, preferably R.sup.01 and R.sup.02 are different from each other selected from F, Cl, CN or OCF.sub.3, more preferably one of them is F, CN or OCF.sub.3, most preferably one of them is CN or OCF.sub.3.

(30) Further preferred according to the present application are compounds of formula I as defined above, wherein additionally or alternatively to any of the previous preferred conditions at least one, preferably one, of the linking groups Z.sup.01 to Z.sup.03 in the respective mesogenic groups MG.sup.1 and MG.sup.2 is different from each a single bond, and preferably is COO, OCO, OCOO, OCH.sub.2, CH.sub.2O, OCF.sub.2 CF.sub.2O or O, more preferably COO, COO, OCF.sub.2 CF.sub.2O or O, more preferably-COO, COO or O, and most preferably COO or COO.

(31) A smaller group of preferred compounds of formula A-0 preferably used in the media according to the present application are those wherein the mesogenic groups MG.sup.01 and MG.sup.02 have one of the meanings listed below. For reasons of simplicity, Phe in these groups is 1,4-phenylene, PheL is a 1,4-phenylene group which is substituted by 1 to 4 groups L, with L being preferably F, Cl, CN, OH, NO.sub.2 or an optionally fluorinated alkyl, alkoxy or alkanoyl group with 1 to 7 C atoms, very preferably F, Cl, CN, OH, NO.sub.2, CH.sub.3, C.sub.2H.sub.5, OCH.sub.3, OC.sub.2H.sub.5, COCH.sub.3, COC.sub.2H.sub.5, COOCH.sub.3, COOC.sub.2H.sub.5, CF.sub.3, OCF.sub.3, OCHF.sub.2, OC.sub.2F.sub.5, in particular F, Cl, CN, CH.sub.3, C.sub.2H.sub.5, OCH.sub.3, COCH.sub.3 and OCF.sub.3, most preferably F, Cl, CH.sub.3, OCH.sub.3 and COCH.sub.3 and Cyc is 1,4-cyclohexylene. This list comprises the sub-formulae shown below as well as their mirror images.

(32) MG.sup.01 preferably is selected from the group of the following formulae
-Phe-Z-Phe-II-1
-Phe-Z-Cyc-II-2
-Cyc-Z-Cyc-II-3
-Phe-Z-PheL-II-4
-PheL-Z-Phe-II-5
-PheL-Z-Cyc-II-6
-PheL-Z-PheL-II-7
whereas MG.sup.02 preferably is selected from the group of the following formulae
-Phe-Z-Phe-Z-Phe-II-8
-Phe-Z-Phe-Z-Cyc-II-9
-Phe-Z-Cyc-Z-Phe-II-10
-Cyc-Z-Phe-Z-Cyc-II-11
-Phe-Z-Cyc-Z-Cyc-II-12
-Cyc-Z-Cyc-Z-Cyc-II-13
-Phe-Z-Phe-Z-PheL-II-14
-Phe-Z-PheL-Z-Phe-II-15
-PheL-Z-Phe-Z-Phe-II-16
-PheL-Z-Phe-Z-PheL-II-17
-PheL-Z-PheL-Z-Phe-II-18
-PheL-Z-PheL-Z-PheL-II-19
-Phe-Z-PheL-Z-Cyc-II-20
-Phe-Z-Cyc-Z-PheL-II-21
-Cyc-Z-Phe-Z-PheL-II-22
-PheL-Z-Cyc-Z-PheL-II-23
-PheL-Z-PheL-Z-Cyc-II-24
-PheL-Z-Cyc-Z-Cyc-II-25
-Cyc-Z-PheL-Z-Cyc-II-26 wherein Cyc is 1,4-cyclohexlene, preferably trans-1,4-cyclohexlene, Phe is 1,4-phenylene, PheL is 1,4-phenylene, which is substituted by one, two or three fluorine atoms, by one or two Cl atoms or by one Cl atom and one F atom, by one or two CH.sub.3 groups atoms or by one CH.sub.3 group atom and one F atom, and Z has one of the meanings of Z.sup.01 as given under partial formula II, at least one is preferably selected from COO, OCO, OCOO, OCH.sub.2, CH.sub.2O, OCF.sub.2 or CF.sub.2O.

(33) Particularly preferred are the sub-formulae II-1, II-4, II-5, II-7, II-8, II-14, II-15, II-16, II-17, II-18 and II-19.

(34) In these preferred groups Z in each case independently has one of the meanings of Z.sup.01 as given under formula I. Preferably one of Z is COO, COO, CH.sub.2O, OCH.sub.2, CF.sub.2O or OCF.sub.2, more preferably COO, OCH.sub.2 or CF.sub.2O, and the others preferably are a single bond.

(35) Very preferably the mesogenic group MG.sup.01 is selected from the following group of formulae IIa to IIf and their mirror images

(36) ##STR00011##
and the mesogenic group MG.sup.02 is selected from the following formulae IIg to IIr (the two reference Nos. II i and II l being deliberately omitted herein to avoid any confusion) and their mirror images

(37) ##STR00012##
wherein
L is in each occurrence independently of each other F, Cl or CH.sub.3, preferably F and
r is in each occurrence independently of each other 0, 1, 2 or 3, preferably 0, 1 or 2.

(38) The group

(39) ##STR00013##
in these preferred formulae is very preferably denoting

(40) ##STR00014##
furthermore

(41) ##STR00015##
L is in each occurrence independently of each other F, Cl or CH.sub.3, preferably F.

(42) In case of compounds of formula I with an unpolar end group, R.sup.01 and/or R.sup.02 are preferably alkyl with up to 15 C atoms or alkoxy with 2 to 15 C atoms.

(43) If R.sup.01 or R.sup.02 is an alkyl or alkoxy radical, i.e. where the terminal CH.sub.2 group is replaced by O, this may be straight-chain or branched. It is preferably straight-chain, has 2, 3, 4, 5, 6, 7 or 8 carbon atoms and accordingly is preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy or octoxy, furthermore methyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy or tetradecoxy, for example.

(44) Oxaalkyl, i.e. where one CH.sub.2 group is replaced by O, is preferably straight-chain 2-oxapropyl (=methoxymethyl), 2-(=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl or 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl, for example.

(45) In case of a compounds with a terminal polar group, R.sup.01 and R.sup.02 are selected from CN, NO.sub.2, halogen, OCH.sub.3, OCN, SCN, COR.sup.x, COOR.sup.x or a mono- oligo- or polyfluorinated alkyl or alkoxy group with 1 to 4 C atoms.

(46) R.sup.x is optionally fluorinated alkyl with 1 to 4, preferably 1 to 3 C atoms. Halogen is preferably F or Cl.

(47) Especially preferably R.sup.01 and R.sup.02 in formula I are selected of H, F, Cl, CN, NO.sub.2, OCH.sub.3, COCH.sub.3, COC.sub.2H.sub.5, COOCH.sub.3, COOC.sub.2H.sub.5, CF.sub.3, C.sub.2F.sub.5, OCF.sub.3, OCHF.sub.2, and OC.sub.2F.sub.5, in particular of H, F, Cl, CN, OCH.sub.3 and OCF.sub.3, especially of H, F, CN and OCF.sub.3.

(48) In addition, compounds of formula I containing an achiral branched group R.sup.01 and/or R.sup.02 may occasionally be of importance, for example, due to a reduction in the tendency towards crystallisation. Branched groups of this type generally do not contain more than one chain branch. Preferred achiral branched groups are isopropyl, isobutyl (=methylpropyl), isopentyl (=3-methylbutyl), isopropoxy, 2-methyl-propoxy and 3-methylbutoxy.

(49) The spacer group Sp.sup.1 is preferably a linear or branched alkylene group having 1, 3 or 5 to 40 C atoms, in particular 1, 3 or 5 to 25 C atoms, very preferably 1, 3 or 5 to 15 C atoms, and most preferably 5 to 15 C atoms, in which, in addition, one or more non-adjacent and non-terminal CH.sub.2 groups may be replaced by O, S, NH, N(CH.sub.3), CO, OCO, OCOO, COS, CH(halogen)-, CH(CN), CHCH or

(50) Terminal CH.sub.2 groups are those directly bonded to the mesogenic groups. Accordingly, non-terminal CH.sub.2 groups are not directly bonded to the mesogenic groups MG.sup.01 and MG.sup.02.

(51) Typical spacer groups are for example (CH.sub.2).sub.o, (CH.sub.2CH.sub.2O).sub.pCH.sub.2CH.sub.2, with o being an integer from 5 to 40, in particular from 5 to 25, very preferably from 5 to 15, and p being an integer from 1 to 8, in particular 1, 2, 3 or 4.

(52) Preferred spacer groups are pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, diethyleneoxyethylene, dimethyleneoxybutylene, pentenylene, heptenylene, nonenylene and undecenylene, for example.

(53) Especially preferred are inventive compounds of formula I wherein Sp is denoting alkylene with 5 to 15 C atoms. Straight-chain alkylene groups are especially preferred.

(54) Preferred are spacer groups with even numbers of a straight-chain alkylene having 6, 8, 10, 12 and 14 C atoms.

(55) In another embodiment of the present invention are the spacer groups preferably with odd numbers of a straight-chain alkylene having 5, 7, 9, 11, 13 or 15 C atoms. Very preferred are straight-chain alkylene spacers having 7, 9, and 11 C atoms.

(56) Especially preferred are inventive compounds of formula I wherein Sp is denoting complete deuterated alkylene with 5 to 15 C atoms. Very preferred are deuterated straight-chain alkylene groups. Most preferred are partially deuterated straight-chain alkylene groups.

(57) Particularly preferred compounds are selected from the group of formulae given above, which bear 0, 2 or 4 F atoms in lateral positions (i.e. as L).

(58) In a preferred embodiment of the present invention R.sup.01 is OCF.sub.3 and R.sup.02 is OCF.sub.3, F or CN, preferably OCF.sub.3 or CN and most preferably CN.

(59) 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, Houben-Weyl, Methoden der organischen Chemie, Thieme-Verlag, Stuttgart. A preferred method of preparation can be taken from the following synthesis schemes.

(60) The compounds of formula I are preferably accessible according to the following general reaction scheme.

(61) The chiral compounds of component C are preferably selected from the group of compounds of formulae C-I to C-III

(62) Especially preferred for component C are chiral compounds, also called chiral dopants selected from formulae C-I to and C-III,

(63) ##STR00016##
the latter ones including the respective (S,S) enantiomers,
wherein E and F are each independently 1,4-phenylene or trans-1,4-cyclohexylene, v is 0 or 1, Z.sup.0 is COO, COO, CH.sub.2CH.sub.2 or a single bond, and R is alkyl, alkoxy or alkanoyl with 1 to 12 C atoms.

(64) Especially preferred media according to the present application are those from which the following media are excluded

(65) a) a medium consisting of

(66) TABLE-US-00002 Compound No. Abbreviation Conc./% 1 R-5011 2.0 2 F-PGI-ZI-7-Z-PP-N 29.0 3 F-PGI-ZI-9-Z-PUU-N 29.0 4 N-PGI-ZI-7-Z-GP-N 15.0 5 F-UIZIP-7-PZU-F 15.0 6 CC-3-V 5.0 7 PPP-3-N 5.0 100.0
and/or
b) a medium consisting of 90% of the mixture

(67) TABLE-US-00003 Compound No. Abbreviation Conc./% 1 R-5011 2.0 2 F-PGI-ZI-7-Z-PP-N 29.6 3 F-PGI-ZI-9-Z-PP-N 19.4 4 F-UIGI-ZI-9-Z-GP-N 31.6 5 F-PGI-ZI-9-Z-PUU-N 17.4 100.0
and 10% of the following mixture (mixture N1),

(68) TABLE-US-00004 Compound No. Abbreviation Conc./% 1 PY-3-O2 14.5 2 CCY-3-O2 3.5 3 CCY-4-O2 13.5 4 CPY-2-O2 11.0 5 CPY-3-O2 11.0 6 CC-3-V 29.0 7 CPP-3-2 13.5 5 CPPC-3-3 4.0 100.0
and/or
c) a medium consisting of

(69) TABLE-US-00005 Compound No. Abbreviation Conc./% 1 R-5011 1.8 2 N-GIGI-ZI-9-Z-GG-N 8.5 3 N-PGI-ZI-9-Z-GP-N 8.5 4 F-PGI-ZI-9-Z-GP-F 16.8 5 F-UIGI-ZI-9-Z-GP-N 22.6 6 F-PGI-ZI-9-Z-PUU-N 8.4 7 N-GIGI-9-GG-N 25.1 8 N-UIUI-9-UU-N 8.4 100.0
and 10% of the following binary mixture (mixture N2),

(70) TABLE-US-00006 Compound No. Abbreviation Conc./% 1 PP-5-N 50.0 2 PPP-5-N 50.0 100.0
and/or
d) a medium consisting of

(71) TABLE-US-00007 Compound No. Abbreviation Conc./% 1 R-5011 2.0 2 N-PGI-ZI-9-Z-PUU-N 25.0 3 N-PGI-ZI-7-Z-GP-N 9.0 4 N-PGI-ZI-9-Z-GP-N 15.0 5 F-GIP-ZI-9-Z-PG-F 10.0 6 F-UIGI-ZI-9-Z-GP-N 15.0 7 TO-GIGI-ZI-9-Z-GP-N 9.0 8 CC-3-V 7.5 9 PYP-2-3 7.5 100.0
and/or
e) a medium consisting of

(72) TABLE-US-00008 Compound No. Abbreviation Conc./% 1 R-5011 2.0 2 F-PGI-O-9-O-GP-F 16.0 3 F-PG-O-9-O-PP-N 21.4 4 F-PI-ZI-7-Z-PP-N 12.7 5 F-PI-ZI-9-Z-PP-N 10.4 6 N-GIGI-ZI-9-Z-GG-N 8.0 7 F-UIGI-ZI-9-Z-GP-N 9.5 8 CP-3-N 1.4 9 CY-3-O2 1.3 10 PGIGI3-F 2.0 11 CP-3-O1 2.2 12 PTP-1-O2 0.7 13 CCG-V-F 1.0 14 PPTUI-3-2 4.0 15 PPTUI-3-4 7.4 100.0
and/or
f) a medium consisting of

(73) TABLE-US-00009 Composition Compound No. Abbreviation Conc./% 1 R-5011 2.0 2 N-PGI-ZI-9-Z-PUU-N 25.0 3 N-PGI-ZI-9-Z-GP-N 15.0 4 N-PGI-ZI-7-Z-GP-N 9.0 5 F-GIP-ZI-9-Z-PG-F 10.0 6 F-UIGI-ZI-9-Z-GP-N 15.0 7 TO-GIGI-ZI-9-Z-GP-N 9.0 8 CC-3-V 5.0 9 PYP-2-3 5.0 100.0

(74) Especially preferred media according to the present application are those from which the following media are excluded

(75) g) media consisting of 95% of the following mixture

(76) TABLE-US-00010 Compound Concentration/% F-PGI-ZI-9-ZGP-F 25.0 F-PGI-ZI-11-ZGP-F 25.0 FPGI-O-5-O-PP-N 9.5 FPGI-O-7-O-PP-N 39.0 CD-1 1.5 100.0
and 5% of a compound selected from the group of compounds of the following formulae or groups of formulae

(77) ##STR00017## ##STR00018## ##STR00019##
wherein n is an integer from 1 to 15 and where in (CH.sub.2).sub.n one or more CH.sub.2 groups may be replaced by CO,

(78) ##STR00020##
wherein n is an integer
and/or

(79) ##STR00021##
wherein R.sup.11 and R.sup.12 have the respective meaning given for R.sup.01 and R.sup.02 under formula A-0, n is 1, 3, 4 or an integer from 5 to 15 and L is in each occurrence independently of each other F, Cl or CH.sub.3, and/or

(80) ##STR00022##
wherein n is an integer selected from 3 and 5 to 15,
and/or

(81) ##STR00023##
wherein
wherein R.sup.11 and R.sup.12 have the respective meaning given for R.sup.01 and R.sup.02 under formula A-0 and
LG.sup.1 is X.sup.01-Sp.sup.0-X.sup.02
and/o

(82) ##STR00024##
wherein n is an integer selected from 3 and 5 to 15

(83) Further preferred used in the media according to the present application are compounds of formula A-0 as defined above, from which, additionally or alternatively to any of the previous preferred conditions, the compounds of one or more of the following formulae or groups of formulae

(84) ##STR00025## ##STR00026## ##STR00027##
are excluded.

(85) Further preferred used in the media according to the present application are compounds of formula A-0 as defined above, from which, additionally or alternatively to any of the previous preferred conditions, the compounds of one or more of the following formulae or groups of formulae

(86) ##STR00028##
wherein n is an integer from 1 to 15 and where in (CH.sub.2).sub.n one or more CH.sub.2 groups may be replaced by CO,

(87) ##STR00029##
wherein n is an integer
are excluded.

(88) Further preferred used in the media according to the present application are compounds of formula A-0 as defined above, from which, additionally or alternatively to any of the previous preferred conditions, the compounds of one or more of the following formulae or groups of formulae

(89) ##STR00030##
wherein R.sup.11 and R.sup.12 have the respective meaning given for R.sup.01 and R.sup.02 under formula A-0, n is 1, 3, 4 or an integer from 5 to 15 and L is in each occurrence independently of each other F, Cl or CH.sub.3, and

(90) ##STR00031##
wherein n is an integer selected from 3 and 5 to 15
are excluded.

(91) Further preferred used in the media according to the present application are compounds of formula A-0 as defined above, from which, additionally or alternatively to any of the previous preferred conditions, the compounds of one or more of the following formulae or groups of formulae

(92) ##STR00032##
wherein
wherein R.sup.11 and R.sup.12 have the respective meaning given for R.sup.01 and R.sup.02 under formula A-0 and
LG.sup.1 is X.sup.01-Sp.sup.0-X.sup.02
are excluded.

(93) Further preferred used in the media according to the present application are compounds of formula A-0 as defined above, from which, additionally or alternatively to any of the previous preferred conditions, the compounds of one or more of the following formulae or groups of formulae

(94) ##STR00033##
wherein n is an integer selected from 3 and 5 to 15
are excluded.

(95) Preferably used are further compounds of formulae A-I and/or A-II and/or A-III wherein Sp.sup.1, Sp.sup.2 and Sp.sup.3 are each independently (CH.sub.2).sub.n with n an integer from 1 to 15, most preferably an uneven integer, wherein one or more CH.sub.2 groups may be replaced by CO.

(96) Especially preferably used are compounds of formula A-III wherein X.sup.31-Sp.sup.3-X.sup.32 is -Sp.sup.3-O, -Sp.sup.3-COO, -Sp.sup.3-OCO, O-Sp.sup.3-, O-Sp.sup.3-COO, O-Sp.sup.3-OCO, OCO-Sp.sup.3-O, OCO-Sp.sup.3-OCO, COO-Sp.sup.3-O or COO-Sp.sup.3-COO, however under the condition that in X.sup.31-Sp.sup.3-X.sup.32 no two O-atoms are adjacent to one another, no two CHCH groups are adjacent to each other and no two groups selected from OCO, SCO, OCOO, COS, COO and CHCH are adjacent to each other.

(97) Preferably used are compounds of formula A-I in which MG.sup.11 and MG.sup.12 are independently from one another -A.sup.11-(Z.sup.1-A.sup.12).sub.m- wherein Z.sup.1 is COO, OCO, OCOO, OCH.sub.2, CH.sub.2O, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, CF.sub.2CF.sub.2, CHCH, CFCF, CHCHCOO, OCOCHCH, CC or a single bond, A.sup.11 and A.sup.12 are each independently in each occurrence 1,4-phenylene, wherein in addition one or more CH groups may be replaced by N, trans-1,4-cyclo-hexylene in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by O and/or S, 1,4-cyclohexenylene, 1,4-bicyclo-(2,2,2)-octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydro-naphthalene-2,6-diyl, 1,2,3,4-tetrahydro-naphthalene-2,6-diyl, cyclobutane-1,3-diyl, spiro[3.3]heptane-2,6-diyl or dispiro[3.1.3.1]decane-2,8-diyl, it being possible for all these groups to be unsubstituted, mono-, di-, tri- or tetrasubstituted with F, Cl, CN or alkyl, alkoxy, alkylcarbonyl or alkoxycarbonyl groups with 1 to 7 C atoms, wherein one or more H atoms may be substituted by F or Cl, and m is 0, 1, 2 or 3.

(98) Preferably used are compounds of formula A-II in which MG.sup.21 and MG.sup.22 are independently from one another -A.sup.21-(Z.sup.2-A.sup.22).sub.m- wherein Z.sup.2 is COO, OCO, OCOO, OCH.sub.2, CH.sub.2O, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, CF.sub.2CF.sub.2, CHCH, CFCF, CHCHCOO, OCOCHCH, CC or a single bond, A.sup.21 and A.sup.22 are each independently in each occurrence 1,4-phenylene, wherein in addition one or more CH groups may be replaced by N, trans-1,4-cyclo-hexylene in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by O and/or S, 1,4-cyclohexenylene, 1,4-bicyclo-(2,2,2)-octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydro-naphthalene-2,6-diyl, 1,2,3,4-tetrahydro-naphthalene-2,6-diyl, cyclobutane-1,3-diyl, spiro[3.3]heptane-2,6-diyl or dispiro[3.1.3.1]decane-2,8-diyl, it being possible for all these groups to be unsubstituted, mono-, di-, tri- or tetrasubstituted with F, Cl, CN or alkyl, alkoxy, alkylcarbonyl or alkoxycarbonyl groups with 1 to 7 C atoms, wherein one or more H atoms may be substituted by F or Cl, and m is 0, 1, 2 or 3.

(99) Most preferably used are compounds of formula A-III in which MG.sup.31 and MG.sup.32 are independently from one another -A.sup.31-(Z.sup.3-A.sup.32).sub.m- wherein Z.sup.3 is COO, OCO, OCOO, OCH.sub.2, CH.sub.2O, CH.sub.2CH.sub.2, (CH.sub.2).sub.4, CF.sub.2CF.sub.2, CHCH, CFCF, CHCHCOO, OCOCHCH, CC or a single bond, A.sup.31 and A.sup.32 are each independently in each occurrence 1,4-phenylene, wherein in addition one or more CH groups may be replaced by N, trans-1,4-cyclo-hexylene in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by O and/or S, 1,4-cyclohexenylene, 1,4-bicyclo-(2,2,2)-octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydro-naphthalene-2,6-diyl, 1,2,3,4-tetrahydro-naphthalene-2,6-diyl, cyclobutane-1,3-diyl, spiro[3.3]heptane-2,6-diyl or dispiro[3.1.3.1]decane-2,8-diyl, it being possible for all these groups to be unsubstituted, mono-, di-, tri- or tetrasubstituted with F, Cl, CN or alkyl, alkoxy, alkylcarbonyl or alkoxycarbonyl groups with 1 to 7 C atoms, wherein one or more H atoms may be substituted by F or Cl, and m is 0, 1, 2 or 3.

(100) Preferably the compounds of formula A-III are unsymmetric compounds, preferably having different mesogenic groups MG.sup.31 and MG.sup.32.

(101) Generally preferred are compounds of formulae A-I to A-III in which the dipoles of the ester groups present in the mesogenic groups are all oriented in the same direction, i.e. all COO or all OCO.

(102) Especially preferred are compounds of formulae A-I and/or A-II and/or A-III wherein the respective pairs of mesogenic groups (MG.sup.11 and MG.sup.12) and (MG.sup.21 and MG.sup.22) and (MG.sup.31 and MG.sup.32) at each occurrence independently from each other comprise one, two or three six-atomic rings, preferably two or three six-atomic rings.

(103) A smaller group of preferred mesogenic groups of formula II is listed below. For reasons of simplicity, Phe in these groups is 1,4-phenylene, PheL is a 1,4-phenylene group which is substituted by 1 to 4 groups L, with L being preferably F, Cl, CN, OH, NO.sub.2 or an optionally fluorinated alkyl, alkoxy or alkanoyl group with 1 to 7 C atoms, very preferably F, Cl, CN, OH, NO.sub.2, CH.sub.3, C.sub.2H.sub.5, OCH.sub.3, OC.sub.2H.sub.5, COCH.sub.3, COC.sub.2H.sub.5, COOCH.sub.3, COOC.sub.2H.sub.5, CF.sub.3, OCF.sub.3, OCHF.sub.2, OC.sub.2F.sub.5, in particular F, Cl, CN, CH.sub.3, C.sub.2H.sub.5, OCH.sub.3, COCH.sub.3 and OCF.sub.3, most preferably F, Cl, CH.sub.3, OCH.sub.3 and COCH.sub.3 and Cyc is 1,4-cyclohexylene. This list comprises the sub-formulae shown below as well as their mirror images
-Phe-Z-Phe-II-1
-Phe-Z-Cyc-II-2
-Cyc-Z-Cyc-II-3
-PheL-Z-Phe-II-4
-PheL-Z-Cyc-II-5
-PheL-Z-PheL-II-6
-Phe-Z-Phe-Z-Phe-II-7
-Phe-Z-Phe-Z-Cyc-II-8
-Phe-Z-Cyc-Z-Phe-II-9
-Cyc-Z-Phe-Z-Cyc-II-10
-Phe-Z-Cyc-Z-Cyc-II-11
-Cyc-Z-Cyc-Z-Cyc-II-12
-Phe-Z-Phe-Z-PheL-II-13
-Phe-Z-PheL-Z-Phe-II-14
-PheL-Z-Phe-Z-Phe-II-15
-PheL-Z-Phe-Z-PheL-II-16
-PheL-Z-PheL-Z-Phe-II-17
-PheL-Z-PheL-Z-PheL-II-18
-Phe-Z-PheL-Z-Cyc-II-19
-Phe-Z-Cyc-Z-PheL-II-20
-Cyc-Z-Phe-Z-PheL-II-21
-PheL-Z-Cyc-Z-PheL-II-22
-PheL-Z-PheL-Z-Cyc-II-23
-PheL-Z-Cyc-Z-Cyc-II-24
-Cyc-Z-PheL-Z-Cyc-II-25

(104) Particularly preferred are the subformulae II-1, II-4, II-6, II-7, II-13, II-14, II-15, II-16, II-17 and II-18.

(105) In these preferred groups Z in each case independently has one of the meanings of Z.sup.1 as given in formula II. Preferably Z is COO, COO, CH.sub.2CH.sub.2, CC or a single bond, especially preferred is a single bond.

(106) Very preferably the mesogenic groups MG.sup.11 and MG.sup.12, MG.sup.21 and MG.sup.22 and MG.sup.31 and MG.sup.32 are each and independently selected from the following formulae and their mirror images

(107) Very preferably at least one of the respective pairs of mesogenic groups MG.sup.11 and MG.sup.12, MG.sup.21 and MG.sup.22 and MG.sup.31 and MG.sup.32 is, and preferably both of them are each and independently, selected from the following formulae IIa to IIn (the two reference Nos. II i and II l being deliberately omitted to avoid any confusion) and their mirror images

(108) ##STR00034## ##STR00035##
wherein
L is in each occurrence independently of each other F or Cl, preferably F and
r is in each occurrence independently of each other 0, 1, 2 or 3, preferably 0, 1 or 2.

(109) The group

(110) ##STR00036##
in these preferred formulae is very preferably denoting

(111) ##STR00037##
furthermore

(112) ##STR00038##

(113) Particularly preferred are the subformulae IIa, IId, IIg, IIh, IIi, IIk and IIo, in particular the subformulae IIa and IIg.

(114) In case of compounds with an non-polar group, R.sup.11 and R.sup.12, R.sup.21 and R.sup.22 and R.sup.31 and R.sup.32 are preferably alkyl with up to 15 C atoms or alkoxy with 2 to 15 C atoms.

(115) If R.sup.11 and R.sup.12, R.sup.21 and R.sup.22 and R.sup.31 and R.sup.32 are an alkyl or alkoxy radical, i.e. where the terminal CH.sub.2 group is replaced by O, this may be straight-chain or branched. It is preferably straight-chain, has 2, 3, 4, 5, 6, 7 or 8 carbon atoms and accordingly is preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, or octoxy, furthermore methyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy or tetradecoxy, for example.

(116) Oxaalkyl, i.e. where one CH.sub.2 group is replaced by O, is preferably straight-chain 2-oxapropyl (=methoxymethyl), 2-(=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3-, or 4-oxapentyl, 2-, 3-, 4-, or 5-oxahexyl, 2-, 3-, 4-, 5-, or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl or 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl, for example.

(117) In case of a compounds with a terminal polar group, R.sup.11 and R.sup.12, R.sup.21 and R.sup.22 and R.sup.31 and R.sup.32 are selected from CN, NO.sub.2, halogen, OCH.sub.3, OCN, SCN, COR.sup.x, COOR.sup.x or a mono- oligo- or polyfluorinated alkyl or alkoxy group with 1 to 4 C atoms. R.sup.x is optionally fluorinated alkyl with 1 to 4, preferably 1 to 3 C atoms. Halogen is preferably F or Cl.

(118) Especially preferably R.sup.11 and R.sup.12, R.sup.21 and R.sup.22 and R.sup.31 and R.sup.32 in formulae A-I, A-II, respectively A-III are selected of H, F, Cl, CN, NO.sub.2, OCH.sub.3, COCH.sub.3, COC.sub.2H.sub.5, COOCH.sub.3, COOC.sub.2H.sub.5, CF.sub.3, C.sub.2F.sub.5, OCF.sub.3, OCHF.sub.2, and OC.sub.2F.sub.5, in particular of H, F, Cl, CN, OCH.sub.3 and OCF.sub.3, especially of H, F, CN and OCF.sub.3.

(119) In addition, compounds of formulae A-I, A-II, respectively A-III containing an achiral branched group R.sup.11 and/or R.sup.21 and/or R.sup.31 may occasionally be of importance, for example, due to a reduction in the tendency towards crystallization. Branched groups of this type generally do not contain more than one chain branch. Preferred achiral branched groups are isopropyl, isobutyl (=methylpropyl), isopentyl (=3-methylbutyl), isopropoxy, 2-methyl-propoxy and 3-methylbutoxy.

(120) The spacer groups Sp.sup.1, Sp.sup.2 and Sp.sup.3 are preferably a linear or branched alkylene group having 5 to 40 C atoms, in particular 5 to 25 C atoms, very preferably 5 to 15 C atoms, in which, in addition, one or more non-adjacent and non-terminal CH.sub.2 groups may be replaced by O, S, NH, N(CH.sub.3), CO, OCO, OCOO, COS, CH(halogen)-, CH(CN), CHCH or

(121) CC.

(122) Terminal CH.sub.2 groups are those directly bonded to the mesogenic groups. Accordingly, non-terminal CH.sub.2 groups are not directly bonded to the mesogenic groups R.sup.11 and R.sup.12, R.sup.21 and R.sup.22 and R.sup.31 and R.sup.32.

(123) Typical spacer groups are for example (CH.sub.2).sub.o, (CH.sub.2CH.sub.2O).sub.pCH.sub.2CH.sub.2, with o being an integer from 5 to 40, in particular from 5 to 25, very preferably from 5 to 15, and p being an integer from 1 to 8, in particular 1, 2, 3 or 4.

(124) Preferred spacer groups are pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, diethyleneoxyethylene, dimethyleneoxybutylene, pentenylene, heptenylene, nonenylene and undecenylene, for example.

(125) Especially preferred are compounds of formulae A-I, A-II and A-III wherein Sp.sup.1, Sp.sup.2, respectively Sp.sup.3 are alkylene with 5 to 15 C atoms. Straight-chain alkylene groups are especially preferred.

(126) Preferred are spacer groups with even numbers of a straight-chain alkylene having 6, 8, 10, 12 and 14 C atoms.

(127) In another embodiment of the present invention are the spacer groups preferably with odd numbers of a straight-chain alkylene having 5, 7, 9, 11, 13 and 15 C atoms. Very preferred are straight-chain alkylene spacers having 5, 7, or 9 C atoms.

(128) Especially preferred are compounds of formulae A-I, A-II and A-III wherein Sp.sup.1, Sp.sup.2, respectively Sp.sup.3 are completely deuterated alkylene with 5 to 15 C atoms. Very preferred are deuterated straight-chain alkylene groups. Most preferred are partially deuterated straight-chain alkylene groups.

(129) Preferred are compounds of formula A-I wherein the mesogenic groups R.sup.11-MG.sup.11- and R.sup.12-MG.sup.1- are different. Especially preferred are compounds of formula A-I wherein R.sup.11-MG.sup.11- and R.sup.12-MG.sup.12- in formula A-I are identical.

(130) Preferred compounds of formula A-I are selected from the group of compounds of formulae A-I-1 to A-I-3

(131) ##STR00039##
wherein the parameter n has the meaning given above and preferably is 3, 5, 7 or 9, more preferably 5, 7 or 9.

(132) Preferred compounds of formula A-II are selected from the group of compounds of formulae A-II-1 to A-II-4

(133) ##STR00040##
wherein the parameter n has the meaning given above and preferably is 3, 5, 7 or 9, more preferably 5, 7 or 9.

(134) Preferred compounds of formula A-III are selected from the group of compounds of formulae A-III-1 to A-III-11

(135) ##STR00041## ##STR00042##
wherein the parameter n has the meaning given above and preferably is 3, 5, 7 or 9, more preferably 5, 7 or 9.

(136) Particularly preferred exemplary compounds of formulae A-I are the following compounds:

(137) symmetrical ones:

(138) ##STR00043##
and non-symmetrical ones:

(139) ##STR00044##

(140) Particularly preferred exemplary compounds of formulae A-II are the following compounds:

(141) symmetrical ones:

(142) ##STR00045## ##STR00046##
and non-symmetrical ones:

(143) ##STR00047##

(144) Particularly preferred exemplary compounds of formulae A-III are the following compounds:

(145) symmetrical ones:

(146) ##STR00048## ##STR00049##
and non-symmetrical ones:

(147) ##STR00050## ##STR00051## ##STR00052##

(148) The compounds of formulae B-I to B-III are either known to the expert and 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, Houben-Weyl, Methoden der organischen Chemie, Thieme-Verlag, Stuttgart.

(149) The compounds of formulae A-I to A-III 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, Houben-Weyl, Methoden der organischen Chemie, Thieme-Verlag, Stuttgart. A preferred method of preparation can be taken from the following synthesis scheme.

(150) The bimesogenic compounds of formulae A-I to A-III are either known to the expert, can be prepared by known methods analogously to known compounds or are prepared according to the following general reaction schemes.

(151) ##STR00053##
wherein n has the meaning of (n2) as given in the definition of Sp.sup.1 above and the reaction conditions for the various stages, respectively steps, are as follows.
Stage 1: Pd(PPh.sub.3).sub.2Cl.sub.2, CuI, THF, N(C.sub.2H.sub.5).sub.3 heated under reflux,
Stage 2: Pd/C, THF, [H.sub.2],
Stage 3: Pd(PPh.sub.3).sub.2Cl.sub.2, NaCO.sub.3, H.sub.2O, THF, heated under reflux,
Stage 4: NaOH, C.sub.2H.sub.5OH,
Stage 5: Pd(dppf).sub.2Cl.sub.2, KPO.sub.4, THF, heated under reflux,
Stage 6: Pd(dppf).sub.2Cl.sub.2, KPO.sub.4, THF, heated under reflux,
Stage 7: BBr.sub.3, DCM and
Stage 8: TFAA, DCM.

(152) All phenylene moieties shown in this scheme and in any of the following schemes may independently of each other be optionally bearing one, two or three, preferably one or two, F atoms or one Cl atom or one Cl and one F atom.

(153) ##STR00054##
wherein R independently in each appearance has the meaning given for R.sup.11 and R.sup.12 including the preferred meanings of these groups, most preferably is F or CN, and the conditions of the successive reactions are as follows:
a) CuI, Pd(PPh.sub.3).sub.2Cl.sub.2, Triethylamine, 30 C.;
b) [H.sub.2], Pd/C;
c) n-BuLi, CO.sub.2, 70 C.;
d) DCC, DMAP, DCM, 25 C.; and
e) Pd(PPh.sub.3).sub.2Cl.sub.2, NaCO3, THF, under reflux.

(154) All phenylene moieties shown in this scheme and in the following schemes may independently of each other be optionally bearing one, two or three, preferably one or two, F atoms or one Cl atom or one Cl and one F atom.

(155) An exemplary reaction scheme for the preparation of such a fluorinated compound is shown in the following scheme.

(156) ##STR00055##
wherein R independently in each appearance has the meaning given under scheme I and the conditions of the successive reactions are also as given under scheme I.

(157) ##STR00056##
wherein R independently in each appearance has the meaning given for R.sup.11 and R.sup.12 including the preferred meanings of these groups, most preferably is F or CN, and the conditions of the successive reactions are as follows:
a) benzylbromide, K.sub.2CO.sub.3, butanone, 80 C.;
b) CuI, Pd(PPh.sub.3).sub.2Cl.sub.2, Triethylamine, 30 C.;
c) [H.sub.2], Pd/C; and
d) K.sub.2CO.sub.3, butanone, 80 C.

(158) ##STR00057##
wherein the conditions of the successive reactions are as given under scheme III. Steps d) and e) are performed under the same conditions.

(159) ##STR00058##
wherein R independently in each appearance has the meaning given for R.sup.11 and R.sup.12 including the preferred meanings of these groups, most preferably is F or CN, and the conditions of the successive reactions are as follows:
a) CuI, Pd(PPh.sub.3).sub.2Cl.sub.2, Triethylamine, 30 C.;
b) [H.sub.2], Pd/C;
c) n-BuLi, THF, 70 0 C., CO.sub.2;
d) HSC.sub.3H.sub.6SH, CF.sub.3SO.sub.3H, 130 C.; and
e) N(C.sub.2H.sub.5).sub.3, 3HF.N(C.sub.2H.sub.5).sub.3, 70 C.

(160) ##STR00059##
wherein the conditions of the successive reactions are as follows:
a) (i) HBr, 0 C.; (ii) H.sub.2O.sub.2, 0 C.;
b) DCC, DMAP, DCM;
c1) AlCl.sub.3, S(CH.sub.3).sub.2, DCM, 0 C.;
c2) K.sub.2CO.sub.3, butanone, 80 C.; and
d) K.sub.2CO.sub.3, butanone, 80 C.

(161) The compounds of formula A-II can be synthesized preferably by the method shown in following synthesis scheme, reaction scheme VII.

(162) ##STR00060##
a) K.sub.2CO.sub.3, THF, H.sub.2O, Pd catalyst, 80 C., 24 hours
b) THF, Et.sub.3N, CuI, Pd catalyst, 40 C., 24 hours
c) THF, Pd/C, H.sub.2, 60 C., 95 bar
d) n-BuLi, THF, I.sub.2. 70 C.
e) Na.sub.2CO.sub.3, THF, H.sub.2O, Pd catalyst, 80 C., 24 hours
wherein R independently in each occurrence has the meaning of R.sup.11 and R.sup.12, o, L and r are at each occurrence independently from each other as defined above, including the preferred meanings of these groups.

(163) ##STR00061##

COMPOUND AND SYNTHESIS EXAMPLES

Synthesis Example 1: Preparation of: F-GIGI-5-Z-PUU-N

(164) ##STR00062##
Reaction Scheme for Synthesis Example 1

(165) ##STR00063##
Step 1.1

(166) ##STR00064##

(167) Methyl 5-hexynoate (15.5 g, 122.86 mmol), 4-bromo-3-fluoroiodobenzene (36.97 g, 122.86 mmol), diisopropylamine (45 ml) and THF (225 ml) are placed into a 3 necked round bottom flask under nitrogen atmosphere. The flask is evacuated three times and subsequently filled with nitrogen, then treated in an ultrasonic bath to degas the reaction mixture, a procedure shortly referred to as ultasonication in this application, for 30 minutes to remove dissolved gasses, and again flushed with more nitrogen. Pd(Ph.sub.3P).sub.2Cl.sub.2 (0.33 g) and CuI (0.165 g) are added to the mixture each in one portion with stirring. The mixture is then warmed up to a temperature of 30 C. for 20 minutes and then to 40 C. for 1 hour. The mixture is subsequently cooled to room temperature (throughout this application room temperature and ambient temperature are used synonymously and mean a temperature of approximately 20 C. unless explicitly stated otherwise) and the solids are filtered off and washed with ethyl acetate. The crude product is concentrated under reduced pressure to give a dark colored solid that is dissolved in minimum Dichloromethane and placed onto a column of silica, eluted with first a mixture of petroleum ether:dichloromethane (2:1 ratio) and then petroleum ether:dichloromethane (1:1 ratio) once the product starts to elute. The appropriate fractions are combined and concentrated to give the intermediate product.

(168) Step 1.2

(169) ##STR00065##

(170) Platinum on carbon (2.7 g, 10% on carbon) is placed under a nitrogen atmosphere in a 1 liter 3 necked round bottom flask. To this is added tetrahydrofuran (270 ml) and the intermediate product of the previous step, step 1.1, (26.9 g, 89.9 mmol). The flask is flushed twice with hydrogen gas, the mixture is then stirred very vigorously for 5 hours under a hydrogen atmosphere The mixture is filtered through Celite filter aid to give a clear solution. This solution is concentrated under reduced pressure to give the intermediate product.

(171) Step 1.3

(172) ##STR00066##

(173) A mixture of the intermediate product of the previous step, step 1.2, (26 g, 86.9 mmol), 3,4-difluorobenzeneboronic acid (13.74 g, 87 mmol), potassium phosphate (72.7 g, 316 mmol), dioxan (160 ml), water (80 ml) and Pd(dppf)Cl.sub.2 (615 mg) are ultrasonicated under a nitrogen atmosphere for 30 minutes and then heated to a temperature of 90 C. for 16 hours. The mixture is the cooled to room temperature, which is approximately 20 C. for the purpose of this application, the phases are separated and the organic material concentrated under reduced pressure. The resulting dark solid is dissolved in minimum dichloromethane and purified on a column of silica, eluted with a mixture of petroleum ether:dichloromethane (1:1 ratio). Concentration of the appropriate fractions gives the product as a clear, transparent oil.

(174) Step 1.4

(175) ##STR00067##

(176) The intermediate product of the previous step, step 1.3, (22 g, 65.4 mmol), NaOH (5.23 g, 131 mmol), ethanol (100 ml) and water (100 ml) are heated to a temperature of 100 C. for 2 hours under a nitrogen atmosphere. The mixture is cooled and reduced in volume by half under reduced pressure, acidified with concentrated Hydrochloric acid, cooled in an ice bath and allowed to crystallize. The precipitate is filtered off in vacuo and washed with water. Recrystallisation is performed from solution in a mixture ethanol/water (1:1 ratio). The crystals are filtered in vacuo, washed first with a little (approximately 5 ml to 10 ml) of a mixture of ethanol:water (1:1 ratio), then with petroleum ether. After drying in a vacuum oven, the intermediate product is isolated.

(177) Step 1.5

(178) ##STR00068##

(179) 4-Methoxyphenylboronic acid (23.8 g, 157 mmol), 4-iodo-2,6-difluorobromobenzene (50 g, 157 mmol), dioxane (200 ml), water (100 ml) and potassium phosphate hydrate (40 g, 174 mmol) are ultrasonicated for 15 minutes. Then [1,1-Bis(diphenylphosphino)ferrocene]dichloropalladium (II) (1.5 g, 2.1 mmol) is added and the mixture heated to a temperature of 40 C. for 6 hours. The mixture is then cooled to room temperature. The two resultant phases are separated and the aqueous layer extracted with toluene. The organic phases are combined and the solvent is removed in vacuo. The residue is dissolved in heptane (200 ml) and purified by vacuum flash chromatography on silica (230 g), eluted with a mixture of heptane/DCM and the fractions, which contain product, are combined.

(180) The solvent is removed in vacuo and the residue is recrystallised from ethanol (120 ml) to give the intermediate product.

(181) Step 1.6

(182) ##STR00069##

(183) The intermediate product of the previous step, step 1.5, (34 g, 114 mmol), 3,5-difluoro-4-cyanophenylboronic ester (30.2 g, 114 mmol), dioxane (200 ml), water (100 ml) and potassium phosphate hydrate (55 g, 239 mmol) are ultrasonicated for 15 minutes. Then [1,1-Bis(diphenyl-phosphino)-ferrocene]dichloropalladium (II) (1.4 g, 1.9 mmol) is added and the mixture heated to a temperature of 90 C. for 5 hours. The mixture is then cooled to room temperature and left for 16 hours at that temperature. A dark black crystalline solid is formed. The solid is filtered off in vacuo and washed with water. The solid is the recrystallised from a mixture of dichloromethane (100 ml) and acetonitrile (100 ml), which is cooled to 0 C. The resultant solid is filtered off in vacuo and washed with acetonitrile to give the intermediate product.

(184) Step 1.7

(185) ##STR00070##

(186) The intermediate product of the previous step, step 1.6, (34.5 g, 97 mmol) is dissolves in dichloromethane (400 ml), stirred and cooled to a temperature of 60 C. under a nitrogen atmosphere. A solution of boron tribromide (200 ml, 1 M in DCM, 200 mmol) is added dropwise over a time of 40 minutes while keeping the temperature of the reaction mixture at a temperature in the range from 60 C. to 70 C. The mixture is then allowed to slowly warm up to room temperature and stirred for another 16 hours. The mixture is then cooled to a temperature of 10 C. in an ice bath. Then water (200 ml) is added dropwise over a time of 30 minutes while keeping the temperature of the reaction mixture at a temperature in the range from at 5 to 15 C. It is then stirred for 1 hour and then the solids are filtered off in vacuo and washed with water to give the intermediate product.

(187) Step 1.8

(188) ##STR00071##

(189) The intermediate acid from step 1.4 (3.04 g, 9.4 mmol) and DCM (10 ml) are stirred at room temperature. Trifluoroacetic anhydride (1.6 ml, 11.5 mmol) is added and the mixture stirred at a temperature of 30 C. for 2 hours. Then the intermediate phenol from step 1.7 (3.4 g, 10 mmol) was added and the mixture is then stirred for a further 4 hours at the temperature of 30 C. and subsequently for another 16 hours at room temperature. Water (50 ml) is added to the mixture and the two phases are separated. The aqueous phase is extracted three times with DCM (50 ml each). The organic phase is dried over anhydrous sodium sulphate, filtered and the solvent removed in vacuo. The residue is purified by vacuum flash chromatography on silica (60 g) eluting with toluene (100 ml fractions). Fractions 1 to 4 are combined and the solvent removed in vacuo. The solid is recrystallised from acetonitrile (25 ml) to give the desired product.

(190) ##STR00072##

(191) The product has the following phase range: K (87.7 N) 106.1 I and an e/K of 1.95 Cm.sup.1N.sup.1 (=1.95 V.sup.1). The e/K has been measured for mixture M-1 as specified below.

Compound Examples 2 and Following

(192) The following compounds of formula I are prepared analogously.

(193) ##STR00073##

(194) Phase sequence: K 146.4 N 166.9 I; e/K=2.61 Cm.sup.1N.sup.1.

(195) ##STR00074##

(196) Phase sequence: K (107.4 N) 125.1 I; e/K=2.16 Cm.sup.1N.sup.1.

(197) ##STR00075##

(198) Phase sequence: K (107.4 N) 125.1 I; e/K=1.81 Cm.sup.1N.sup.1.

(199) ##STR00076##

(200) Phase sequence: K 123.7 N 155.0 I; e/K=1.87 Cm.sup.1N.sup.1.

(201) ##STR00077##

(202) Phase sequence: K 91.7 N 176.6 I; e/K=2.06 Cm.sup.1N.sup.1.

(203) ##STR00078##

(204) Phase sequence: K 93.8 N 221.8 I; e/K=1.97 Cm.sup.1N.sup.1.

(205) ##STR00079##

(206) Phase sequence: K (27.9 N) 56.0 I; e/K=2.05 Cm.sup.1N.sup.1.

(207) ##STR00080##

(208) Phase sequence: K 111.9 N 180.3 I; e/K=1.84 Cm.sup.1N.sup.1.

(209) ##STR00081##

(210) Phase sequence: K 89.0 N 139.0 I; e/K=2.00 Cm.sup.1N.sup.1.

(211) The materials in the table above generally show increased performance in the screening mixtures, as compared to known, more conventional bimesogenic compounds as e.g. those shown in the table below.

Synthesis Example 11

Preparation of N-PGIZIGI-9-GZGP-N

(212) ##STR00082##
Step 11.1

(213) ##STR00083##

(214) 55.1 g (183 mmol) of the iodobromofluorobenzene and 60 ml tetrahydrofuran are added to a reaction flask, which is evacuated three times and subsequently filled with nitrogen, then treated in an ultrasonic bath to degas the reaction mixture, a procedure shortly referred to as ultasonication in this application, for 10 min. with additional evacuation/purging with nitrogen. Pd(PPh.sub.3).sub.2Cl.sub.2 (1.8 g, 2.6 mmol) and CuI (0.4 g, 2.1 mmol) as catalysts and diisopropylamine (60 ml) are added and the reaction vessel is purged again before being ultrasonicated for 10 minutes and then placed in a large water bath to control the reaction temperature.

(215) 1,8-nonadiyne (10 g, 83 mmol) are added slowly over a time span of 15 minutes a fine precipitate is formed. The reaction mixture is stirred overnight at ambient temperature.

(216) The reaction mixture is then filtered under vacuum and the filter pad washed with Dichloromethane. The filtrate is concentrated to a semi-solid, which is re-dissolved in dichloromethane before being passed through a silica column to purify. The target product is eluted with additional dichloromethane before final isolation by re-crystallisation from petroleum ether.

(217) Step 11.2

(218) ##STR00084##

(219) The hydrogenation reaction is performed in an H-Cube-hydrogenation apparatus. The parameters of the reaction are as follows: Flow rate: 7 ml/min, Mode: 100% H.sub.2, Catalysts: Pt/C, Temperature: 50 C. and Pressure: 30 bar.

(220) Step 11.3

(221) ##STR00085##

(222) Anhydrous tetrahydrofuran is charged into a three neck flask together with 9.4 g (19.8 mmol) of the dibromide with the saturated spacer. The flask is evacuated and filled with nitrogen. The reaction mixture is stirred and cooled to a temperature of 75 C. in a bath of acetone cooled by solid CO.sub.2.

(223) Then 31 ml 1.6 M, (49.5 mmol) n-butyl lithium are added drop wise over a time span of 30 minutes while keeping the temperature at 75 C. After 3 hours further stirring 8.7 g (200 mmol) of crushed, solid CO.sub.2 are cautiously added to the reaction mixture. A thick white sludge develops and this is stirred for a further 30 minutes before it is hydrolysed by the addition of dilute HCl. The mixture is extracted three times with diethyl ether, and the combined organic material washed with water until neutral. Then toluene is added and the whole solvent is solution is evaporated. The solid the product is isolated and used in the following without further purification.

(224) Step 11.4

(225) ##STR00086##

(226) 4.9 g (24 mmol) of the acid intermediate are added to flask filled with 50 ml dichloromethane. This mixture is thoroughly stirred before 6.5 g (31 mmol) of trifluoroacetic anhydride are added dropwise over a time span of 5 minutes. The reaction mixture is then stirred further for 5 minutes.

(227) Then 4.6 g (24.4 mmol) of solid 4-hydroxy-3-fluorobromobenzene are added and the reaction mixture is stirred at a temperature of 35 C. After complete reaction, water is added. The organic and aqueous layers are separated and the aqueous solution is extracted three times with dichloromethane. The combined organic solutions are washed with a solution of sodium carbonate before being dried over magnesium sulphate, filtered and concentrated. The crude product is purified by passing through a silica plug and eluting with a mixture of petrol and dichloromethane (1:2). The final purification is carried out by re-crystallisation from MeCN.

(228) Step 11.5

(229) ##STR00087##

(230) 1.0 g (1.33 mmol) of the bromide intermediate, 0.61 g (2.67 mmol) of 4-cyanophenyl boronate ester, 0.63 g (2.66 mmol) of sodium metaborate octahydrate, 9.0 ml (499 mmol) of water and 37.5 ml (463 mmol) of tetrahydrofuran are filled into a round bottom flask. This mixture is stirred, the flask is evacuated and filled with nitrogen before being ultrasonicated for 30 minutes. Then 0.075 g (0.107 mmol) of palladium dichloride-(bistriphenylphosphine) are added and the vessel is evacuated then filled with nitrogen. The reaction mixture is heated to a temperature of 80 C. for 72 hours under reflux. Then the reaction mixture is cooled, water and diethyl ether are added subsequently. Then the resulting phases are separated. The aqueous phase is extracted twice with diethyl ether, and the combined organic phases are washed twice with water and once with an aqueous solution of NaCl. The organic solution is dried over sodium sulphate, filtered and the solvent evaporated. The crude product is purified over a short silica column, eluted with first petrol then with a mixture of petrol/dichloromethane (2:1). The product is isolated after repeated re-crystallisation from acetonitrile.

(231) ##STR00088##

(232) This compound has the phase sequence: K 130 Sm 255 N 271 I.

Scheme for Synthesis Example 12Preparation of N-PO1GI-9-GO1P-N

(233) ##STR00089##

Synthesis Example 12

(234) Step 12.1

(235) 4-bromofluorophenol (33.9 g, 0.178 moles), benzylbromide (21.1 ml, 0.178 moles), potassium carbonate (34.4 g, 0.25 moles) and butan-2-one (300 ml) are heated together at a temperature of 85 C. under reflux overnight. The mixture is cooled, filtered, washed with butanone and diethyl ether and the solvent removed in vacuo. The material is re-crystallised from heptane at 20 C.

(236) Step 12.2

(237) The bromide (44.5 g, 115.8 mmol) from the previous step, triethylamine (89 ml), tetrahydrofuran (45 ml), Copper(I) Iodide (0.694 g, 3.6 mmol) and bis(triphenylphosphine)Palladium(II)dichloride (3.5 g, 4.91 mmol) are added to a flask and then 1,8-Nonadiyne (9.14 g (76.0 mmol) in tetrahydrofuran (45 ml) is slowly added over a time of 30 minutes. The reaction-mixture is warmed to 40 C. overnight. The mixture is then cooled, filtered and the filter pad washed with diethyl ether. The filtrate is acidified with dilute Hydrochloric acid and then neutralized with sodium hydroxide before drying over sodium sulphate. This was filtered and the solvent from the filtrate removed in vacuo to give a solid product. The solid was pre-adsorbed onto 50 g silica from a dichloromethane solution and columned through a short silica column using 10% DCM in petrol as eluent. The fractions containing the product were collected and re-crystallised first from petrol and then from acetonitrile to afford the clean product.

(238) Step 12.3

(239) The hydrogenation reaction is again performed in a an H-Cube Hydrogenator.

(240) Parameters: Flow: 10 ml/min., Mode: 100% H.sub.2 Catalysts: Pd/C

(241) Temp.: 50 C., Pressure: 30 bar Rising to 80 C. and 80 bar at the end of the reaction.

(242) Step 12.4

(243) The phenol from stage 3 (2.80 g, 8.04 mmol), 4-bromomethylbenzonitrile (3.94 g, 20.09 mmol) and potassium carbonate (1.66 g, 12 mmol) are added to a flask with dimethylformamide (5.87 g) and ethyl methyl ketone (50 ml). The mixture is heated at 85 C. overnight. The mixture is cooled, filtered and the filter pad washed with diethyl ether and the solvent from the filtrate removed in vacuo to give a solid product. This solid crude product is purified over a short silica column using 33% DCM in petrol as eluent. The fractions containing the product are collected and re-crystallised from acetonitrile to afford the clean product.

Scheme for Synthesis Example 13Preparation of N-PO1GI-9-GO1P-F

(244) ##STR00090##

Synthesis Example 13

(245) Steps 13.1 to 13.3 are identical to those of Synthesis example 12.

(246) Step 13.4

(247) The product of the synthesis example 12, step 12.3 (2.50 g, 7.18 mmol), 4-bromomethyl-benzonitrile (2.81 g, 14.4 mmol) and potassium carbonate (1.79 g, 19.9 mmol) are mixed together in ethylmethylketone (50 ml). The reaction mixture is heated under reflux at 80 C. for 12 hours. The reaction-mixture is then cooled and the solid precipitate formed is filtered off under vacuum, the filter pad is washed with ether then the solution is concentrated under reduced pressure. The crude product is purified by chromatography through silica, eluted with 30% DCM in petroleum ether (40-60). The material is then re-crystallised from acetonitrile to yield the desired non symmetrical intermediate alcohol.

(248) Step 13.5

(249) The product from the previous step, step 13.4 (2.15 g, 4.64 mmol), 1-bromomethyl-4-fluorobenzene (1.05 g, 5.56 mmol) and potassium carbonate (1.92 g, 14.0 mmol) are mixed together in ethylmethylketone (50 ml). The reaction mixture is heated under reflux at 80 C. for 18 hours. The reaction-mixture is then cooled and solids filtered off under vacuum, the filter pad is washed with diethyl ether then concentrated under reduced pressure. The crude product is purified by chromatography through silica, eluted with 30% DCM in petroleum ether (40-60). The material was then re-crystallised twice from acetonitrile to afford the product.

Scheme for Synthesis Example 14Preparation of N-PQIP-9-PQP-N

(250) ##STR00091##
Step 14.1

(251) 25.0 g (88.4 mmol) of iodobromobenzene and 80 ml tetrahydrofuran are added to a reaction flask, which is evacuated three times and subsequently filled with nitrogen each time, then ultrasonicated for 10 min. with additional evacuation/purging with nitrogen. Pd(PPh.sub.3).sub.2Cl.sub.2 (0.9 g, 1.3 mmol) and CuI (0.2 g, 1.1 mmol) as catalysts and diisopropylamine (14 ml) are added and the reaction vessel is purged again before being placed back in an ultrasonic bath for 10 minutes and then placed in a large water bath to control the reaction temperature.

(252) 1,8-nonadiyne (5.0 g, 41.6 mmol) is mixed with tetrahydrofuran (20 ml) and added slowly over a time span of 15 minutes. A fine precipitate is formed. The reaction mixture is stirred overnight at ambient temperature. The reaction mixture is then filtered under vacuum and the filter pad washed with tetrahydrofuran. The filtrate is concentrated to a semi-solid, which is re-dissolved in dichloromethane before being passed through a silica column for purification. The target product is eluted with additional dichloromethane to afford a yellow crystalline solid.

(253) Step 14.2

(254) The hydrogenation reaction is performed in an H-Cube-hydrogenation apparatus. The parameters of the reaction are as follows: Flow rate: 7 ml/min., Mode: 100% H.sub.2, Catalysts: Pt/C, Temperature: 50 C., and Pressure: 30 bar.

(255) Step 14.3

(256) Anhydrous tetrahydrofuran is charged into a three neck flask together with 9.4 g (19.8 mmol) of the dibromide from the previous stage. The flask is evacuated and filled with nitrogen. The reaction mixture is stirred and cooled to a temperature of 75 C. in a bath of acetone cooled by solid CO.sub.2.

(257) Then n-butyl lithium (1.6 M, 31 ml, 49.5 mmol) are added drop wise over a time span of 30 minutes while keeping the temperature at 75 C. After 3 hours further stirring 8.7 g (200 mmol) of crushed, solid CO.sub.2 are cautiously added to the reaction mixture. A thick white sludge develops and this is stirred for a further 30 minutes before it is hydrolysed by the addition of dilute HCl. The mixture is extracted three times with diethyl ether, and the combined organic material washed with water until neutral. Then toluene is added and the whole solvent is solution is evaporated. The solid the product is isolated and used in the following without further purification.

(258) Step 14.4

(259) The intermediate product from the previous step (5.5 g, 15 mmol) and propanedithiol (3.6 g, 33 mmol) are added to flask before adding trifluoromethanesulphonic acid (6.8 g, 45 mmol) and starting to stir the mixture. The mixture is heated to 120 C. and the now clear orange mixture is then cooled to ambient before being treated with diethyl ether (300 ml). The resultant solution is added to a flask of vigorously stirred diethyl ether (700 ml) pre-cooled to 70 C. Within 30 minutes fine crystals appear in the stirred mixture. The solid is isolated by filtration under vacuum and washed with ether to give a pale yellow powder which is used immediately.

(260) Step 14.5

(261) The intermediate (10.1 g 12 mmol) from the previous step is added to a flask with dichloromethane (50 ml) and then cooled to 70 C. A mixture of 4-cyanophenol (3.5 g, 30 mmol), dichloromethane (40 ml) and triethylamine (3.5 g, 34 mmol) is added dropwise. After 90 minutes further stirring triethylaminehydrogen fluoride (20 g, 125 mmol) is added dropwise. After a further hour of stirring bromine (19.9 g, 125 mmol) in dichloromethane (100 ml) is added dropwise. The reaction mixture is stirred for 30 minutes and allowed to warm to 30 C. before adding morpholine (10.9 g, 125 mmol) and finally warming to 0 C. where it is stirred for a further time span of 1 hour. The mixture is carefully poured onto a mixture of ice, water and potassium hydroxide, and the layers are separated. The organic material is washed with water, dried over sodium sulphate and concentrated in vacuo. The crude material is purified by flash chromatography, eluting with a solution of 30% DCM in petroleum ether. Final purification is carried out by repeated re-crystallisation from acetonitrile to afford the desired product.

Scheme for Synthesis Example 15Preparation of N-PQIG-9-GQP-N

(262) ##STR00092##

(263) Steps 15.1 to 15.3 are identical to the respective steps of Synthesis Example 11.

(264) Step 15.4

(265) The intermediate product of Synthesis Example 11, step 11.3 (5.5 g, 15 mmol) and propanedithiol (3.6 g, 33 mmol) are added to flask before adding trifluoromethanesulphonic acid (6.8 g, 45 mmol) and starting to stir the mixture. The mixture is heated to 120 C. and the then clear orange mixture is cooled to ambient before being treated with diethyl ether (300 ml). The resultant solution is added to a flask of vigorously stirred diethyl ether (700 ml) pre-cooled to 70 C. Within 30 minutes fine crystals appear in the stirred mixture. The solid is isolated by filtration under vacuum and washed with ether to give a pale yellow powder which is used immediately.

(266) Step 15.5

(267) The intermediate (10.1 g 12 mmol) from the previous step is added to a flask with dichloromethane (50 ml) and then cooled to 70 C. A mixture of 4-cyanophenol (3.5 g, 30 mmol), dichloromethane (40 ml) and triethylamine (3.5 g, 34 mmol) is added dropwise. After 90 minutes further stirring triethylaminehydrogen fluoride (20 g, 125 mmol) is added dropwise. After a further hour of stirring bromine (19.9 g, 125 mmol) in dichloromethane (100 ml) is added dropwise. The reaction mixture is stirred for 30 minutes and allowed to warm to 30 C. before adding morpholine (10.9 g, 125 mmol) and finally warming to 0 C. where it is stirred for a further time span of 1 hour. The mixture is carefully poured onto a mixture of ice, water and potassium hydroxide, and the layers are separated. The organic material is washed with water, dried over sodium sulphate and concentrated in vacuo. The crude material is purified by flash chromatography, eluting with a solution of 30% DCM in petroleum ether. Final purification is carried out by repeated re-crystallisation from acetonitrile to afford the desired product.

Scheme for Synthesis Example 16Preparation of Chiral

(268) ##STR00093##
Step 16.1

(269) ##STR00094##

(270) Methylbutylbiphenyl (44.8 g, 0.2 mol), dichloromethane (250 ml), tetraethylammonium bromide (2.1 g, 10 mmol) and hydrogen bromide (51.6 g, 0.3 mol) are introduced into a reaction flask and cooled to 0 C. Hydrogen peroxide (48.6 g, 0.5 mol) is added with a dosage of 0.1 ml/min.

(271) After the reaction is shown to have completed (by TLC analysis), the reaction is cooled to 0-10 C. and sodium sulfite (17.8 g, 014 mol) as an aqueous solution is added until de-coloration occurs. Thereby, the temperature is maintained at 10 C. The solution turns green. Then the reaction mixture is stirred for 2 hours. Subsequently a 10% sodium carbonate solution is prepared and added. The resultant two phases are separated. The aqueous phase is extracted with 100 ml of dichloromethane and added to the organic phase.

(272) The material is washed with sodium carbonate solution and then water before being concentrated in vacuo.

(273) The residue is then dissolved in 150 ml ethanol and heated for 3 hours under reflux.

(274) The solution is drained and cooled in an ice bath. The resulting crystals are filtered off and dried under ambient atmosphere.

(275) Step 16.2

(276) ##STR00095##

(277) To a stirred solution of the cyano biphenol (25.0 g, 128 mmol) in acetone (625 ml), potassium carbonate (37.5 g, 271 mmol) is added, heated under reflux for 1 hour under a nitrogen atmosphere, and then cooled to ambient temperature. Dibromononane (200 ml, 961 mmol) is then added in a single portion. The reaction mixture is heated again to reflux. After heating under reflux overnight the reaction was cooled and filtered under vacuum, the filter pad washed with dcm, and the filtrate evaporated under reduced pressure to afford the crude material. This was vacuum distilled on Kugelrohr apparatus to remove excess dibromononane affording a solid pale yellow product.

(278) Step 16.3

(279) ##STR00096##

(280) 4-methoxybenzoic acid (10 g, 65.7 mmol), intermediate from step 16.1 (15.7 g, 65.3 mmol), Dicyclohexylcarbodiimide (13.5 g, 65.4 mmol), Dimethylamino pyridine (0.5 g) and Dichloromethane (250 ml) are added to a flask under nitrogen atmosphere stirred at 30 C. overnight. The progress of the reaction procedure is monitored by TLC. When the reaction appears complete, Oxalic acid (5.9 g, 65.7 mmol) is added, then the reaction mixture is filtered using vacuum and the filtrate evaporated to dryness in vacuo. The product is isolated as a white solid.

(281) Step 16.4

(282) ##STR00097##

(283) The ester from step 16.3 (20 g, 53.4 mmol) is dissolved in Dichloromethane (80 ml) and added to a suspension of aluminium chloride (35 g, 262 mmol) in Dichloromethane (80 ml) at a temperature in the range from 0 C. to 5 C. Dimethyl sulphide (21 ml, 284 mmol)) is then added dropwise, while the temperature is maintained below 0 C. and the resulting mixture (brown solution) is stirred overnight.

(284) The reaction is quenched by the addition (which is exothermic) of (saturated) ammonium chloride solution until the resultant mixture is acidic leading to a white solid precipitate, diluted with Dichloromethane and filtered off under vacuum collecting the precipitate.

(285) Step 16.5

(286) ##STR00098##

(287) The intermediate from Step 16.4 (3.5 g, 9.71 mmol), the intermediate from step 5.2 (4.0 g, 9.9 mmol), potassium iodide (1.8 g, 10.9 mmol), potassium carbonate (0.9 g, 6.5 mmol) and dimethylformamide (100 ml) are added to a flask and heated at 100 C. under reflux for 48 hours.

(288) The reaction is cooled, the reaction mixture poured into a mixture of dichloromethane and water, the layers are separated and the organic solution is washed with water, the organics are dried over sodium sulphate, filtered and concentrated in vacuo to yield a yellow solid.

(289) The material is purified by column chromatography, eluting with DCM with increasing amounts of Industrial methylated spirits. The product is re-crystallized from acetone to give the final material.

(290) ##STR00099##

(291) Phase sequence: to be determined.

Compound Examples 17 to 34

(292) The following compounds of formula I are prepared analogously.

(293) ##STR00100## ##STR00101##

(294) Phase sequence: K 69.9 I.

(295) ##STR00102##

(296) Phase sequence: K 109.8 I.

(297) ##STR00103##

(298) Phase sequence: K 77.5 I.

(299) The materials in the above table generally showed increased performance in the screening mixtures, as compared to known, rather conventional bimesogenic compounds.

Example 35: General Synthesis Scheme for Compounds of Formula A-II Wherein R21-MG21- and R22-MG22- in Formula A-II are Identical to Each Other

(300) ##STR00104##
Step 35.1: Synthesis of (1)

(301) 1-bromo-3-fluoroiodobenzene (53.3 g, 0.177 mol) is added to a round bottom flask with 3,5-difluorobenzenboronic acid (29.0 g, 0.184 mol).

(302) Tetrahydrofuran (500 ml) is added and the mixture is stirred under nitrogen until dissolved. A solution of potassium carbonate (36.7 g, 0.265 mol) in water (100 ml) is added to the reaction. A catalyst, bis(triphenylphosphine)-palladium(II) dichloride (1.98 g, 2.83 mmol) is added and the reaction is heated to reflux for 18 hours. The reaction is cooled and diluted with water before being acidified with dilute Hydrochloric acid. The layers are separated and the organics are washed with water before being concentrated to obtain the product as a brown solid.

(303) The crude solid is dissolved in Dichloromethane and adsorbed onto silica gel (100 g) by concentration. The material is purified by column chromatography, eluting with a mixture of petroleum spirit (4060 C.) and dichloromethane to obtain a purified product as a yellow solid.

(304) Step 35.2: Synthesis of (2)

(305) 2,-3-5-trifluoro-4-bromobiphenyl (26.1 g, 0.091 mol) is added to a round bottomed flask. Triethylamine (25.0 ml) and tetrahydrofuran (50.0 ml) is added and the whole evacuated and replaced with nitrogen. Copper(I)iodide (0.404 g, 2.12 mmol) and bis(triphenylphosphine)-palladium(II) dichloride (0.71 g, 1.01 mmol) are added, the reaction is evacuated and replaced with nitrogen. The reaction mixture is heated to 40 C. and 1,8-nonadiyne (5.25 g, 0.044 mol) is slowly added over 30 minutes. The mixture is heated for a further 24 hours at 40 C. followed by 48 hours at 80 C.

(306) The reaction mixture is cooled and filtered under vacuum to remove precipitates. The filtrate is acidified with dilute Hydrochloric acid and extracted with diethyl ether. The organic material is washed with water before concentrating to afford the product as a black solid (26.0 g). The crude solid is dissolved in dichloromethane and adsorbed onto 50.0 g silica gel. The material is purified by column chromatography, eluting the product using a mixture of dichloromethane in petrol.

(307) Step 35.3: Synthesis of (3)

(308) The material (2) (21.5 g, 0.040 mol) is dissolved in Tetrahydrofuran (600 ml) and passed through a Thales nano hydrogenator. The material required conditions of 70 bar pressure and 60 C. to produce the product as pale colored solid.

(309) Step 35.4: Synthesis of (4)

(310) Material (3) (21.5 g, 0.04 mol) is added to a round bottom flask with Tetrahydrofuran (150 ml). The reaction is stirred under nitrogen and cooled to 70 C. n-Butyl Lithium solution (1.6 M in hexanes, 55.0 ml, 0.087 mol) is slowly added over 45 minutes, and the reaction stirred for a further hour at 70 C. A solution of Iodine (45.8 g, 00.179 mol) in tetrahydrofuran (125 ml) is slowly added keeping the temperature between 60 and 70 C. The reaction is stirred overnight and allowed to warm to room temperature. The reaction is quenched by slowly adding wet THF before water and then ethyl acetate is added. The layers are separated and the aqueous extracted three times with ethyl acetate. The organics are washed twice with sodium thiosulphate solution (100 ml, 2 M in water) then washed with water. Concentration afforded a brown solid. The material is purified by sequential recrystallisations from Industrial methylated spirits, acetone and acetonitrile/acetone.

(311) Step 35.5: Synthesis of (5)

(312) 4-bromo-2-fluorobenzonitrile (42.4 g, 212 mmol) is added to a round bottom flask along with bis(pinacolato)diborane (59.8 g, 235 mmol). Potassium acetate (31.1 g, 317 mmol), tricyclohexylphosphine (3.57 g, 12.7 mmol), Tris(dibenzylideneacetone)dipalladium(0) (3.66 g, 6.36 mmol) and 1,4-dioxane (600 ml) are all added to the reaction flask and the mixture stirred under nitrogen at 80 C. for 72 hours. After cooling the reaction mixture, water and diethyl ether are added and the layers separated. The organic material is washed with brine and water before concentrating to a brown solid. The product is purified by recrystallisation from petrol/dichloromethane to obtain a brown crystalline solid.

(313) Step 35.6: Synthesis of (6)

(314) Material (4) (10.17 g, 12.8 mmol) and material (5) (7.70 g, 31.2 mmol) are added to a round bottom flask and dissolved in Tetrahydrofuran (250 ml). Bis(triphenylphosphine)-palladium(II) dichloride (450.6 mg, 0.642 mmol) is added along with a solution of sodium carbonate (1 M in water, 77.0 ml, 77.0 mmol). The reaction is heated to 85 C. for 24 hours, after which it is cooled and diluted with water before being acidified with dilute Hydrochloric acid. The layers are separated and the organic layer is washed with water before being concentrated to yield the product as a brown solid. The material is purified by column chromatography, eluting the product with 40% ethyl acetate in petrol. The product is further purified by recrystallisation from, first, acetone/methanol, then acetone and finally IPA/petrol.

Example 36 to 52

(315) The following compounds of formula A-II are prepared analogously:

(316) ##STR00105##

(317) Phase sequence: K 84.1 SmC 105.7 N 122 I.

(318) ##STR00106##

(319) Phase sequence: to be determined.

(320) ##STR00107## ##STR00108## ##STR00109##

Example 53: General Synthesis for Compounds of Formula A-II Wherein R21-MG21- and R22-MG22- in Formula A-II are Different from One Another

(321) ##STR00110##
Step 53.1: Synthesis of (1)

(322) 1-bromo-3-fluoroiodobenzene (27.5 g, 92 mmol) is added to a round bottom flask with tetrahydrofuran (30 ml) and the mixture is stirred under nitrogen until dissolved. Diisopropylamine (30 ml) is added and the reaction placed in an ultrasonic bath for 10 minutes. Catalysts, bis(triphenyl-phosphine)palladium(II) dichloride (0.9 g, 1.28 mmol) and copper(I)iodide (0.2 g, 1.05 mmol) are added and the reaction is cooled in a water bath to 20 C. 1,8-nonadiyne (5.0 g, 41 mmol) is slowly added to the reaction and stirred for a further 20 hours. The reaction is cooled and filtered under vacuum to remove precipitates. The filtrate is acidified with diluted hydrochloric acid and extracted with diethyl ether. The organic material is washed with water before concentrating to afford the product as a black solid (19 g). The material is purified by column chromatography, eluting the product using a mixture of dichloromethane in petrol. This produces the desired product.

(323) Step 53.2: Synthesis of (2)

(324) Material (1) (21.5 g, 40 mmol) is dissolved in tetrahydrofuran (600 ml) and passed through a Thales nano hydrogenator. The material required conditions of 70 bar pressure and 60 C. to produce the product as pale coloured solid.

(325) Step 53.3: Synthesis of (3)

(326) Material (2) (14.35 g, 30.3 mmol), 4-cyanophenylboronic acid (4.45 g, 30.3 mmol), potassium phosphate (25.4 g, 120 mmol), dioxane (57.4 ml) and water (28.7 ml) are sonicated in an ultrasound bath for 30 minutes under a nitrogen atmosphere. The mixture is stirred at room temperature and Pd(DPPF)Cl.sub.2-DCM complex (215 mg) are added. The mixture is heated to 90 C. for 2 hours. The mixture is cooled. The two layers are separated and the solvent from the organic layer removed in vacuo to give a black oil. This is dissolved in a minimum of DCM and applied to a column of silica eluting with petrol: DCM, 1:1 to give the desired product.

(327) Step 53.4: Synthesis of (4)

(328) Material (3) (3.5 g, 7.05 mmol), 3,4-difluorobenzeneboronic acid (1.7 g, 8 mmol) potassium phosphate (1.7 g, 8 mmol), dioxane (10.6 ml) and water (5.3 ml) are sonicated in an ultrasound bath for 30 minutes under a nitrogen atmosphere. The mixture is stirred at room temperature and Pd(DPPF)Cl.sub.2-DCM complex (59 mg) are added. The mixture is heated to 90 C. for 5 hours. The two layers are separated and the solvent from the organic layer removed in vacuo. This is dissolved in a minimum of DCM and applied to a column of silica, eluting with petrol: DCM, 2:1. The crude product is crystallized twice from DCM/acetonitrile (cooled with dry ice/acetone bath) and the product is dissolved in a minimum of DCM and applied to a column of silica eluting with petrol: DCM, 2:1. The crude product is crystallized from acetonitrile (cooled with dry ice/acetone bath) to give the desired product.

Comparative Compound Examples

(329) ##STR00111##

(330) Phase sequence: K 137 N 181 I.

(331) ##STR00112##

(332) Phase sequence: K 88 (N, 64) I.

(333) ##STR00113##

(334) Phase sequence: K 98 (N, 82.5) I.

(335) Another object of the invention is the use of bimesogenic compounds of formulae A-I and/or A-II and/or A-III in liquid crystalline media.

(336) Compounds of formula A-II, when added to a nematic liquid crystalline mixture, producing a phase below the nematic. In this context, a first indication of the influence of bimesogenic compounds on nematic liquid crystal mixtures was reported by Barnes, P. J., Douglas, A. G., Heeks, S. K., Luckhurst, G. R., Liquid Crystals, 1993, Vol. 13, No. 4, 603-613. This reference exemplifies highly polar alkyl spacered dimers and perceives a phase below the nematic, concluding it is a type of smectic.

(337) A photo evidence of an existing mesophase below the nematic phase was published by Henderson, P. A., Niemeyer, O., Imrie, C. T. in Liquid Crystals, 2001, Vol. 28, No. 3, 463-472, which was not further investigated.

(338) In Liquid Crystals, 2005, Vol. 32, No. 11-12, 1499-1513 Henderson, P. A., Seddon, J. M. and Imrie, C. T. reported, that the new phase below the nematic belonged in some special examples to a smectic C phase. A additional nematic phase below the first nematic was reported by Panov, V. P., Ngaraj, M., Vij, J. K., Panarin, Y. P., Kohlmeier, A., Tamba, M. G., Lewis, R. A. and Mehl, G. H. in Phys. Rev. Lett. 2010, 105, 1678011-1678014.

(339) In this context, liquid crystal mixtures comprising the new and inventive bimesogenic compounds of formulae A-I and/or A-II and/or A-III show also a novel mesophase that is being assigned as a second nematic phase. This mesophase exists at a lower temperature than the original nematic liquid crystalline phase and has been observed in the unique mixture concepts presented by this application.

(340) Accordingly, the bimesogenic compounds of formula A-II according to the present invention allow the second nematic phase to be induced in nematic mixtures that do not have this phase normally. Furthermore, varying the amounts of compounds of formula A-II allow the phase behaviour of the second nematic to be tailored to the required temperature.

(341) Some preferred embodiments of the mixtures according to the invention are indicated below.

(342) Preferred are compounds of formulae A-I and/or A-II and/or A-III wherein the mesogenic groups MG.sup.11 and MG.sup.12, MG.sup.21 and MG.sup.22 and MG.sup.31 and MG.sup.32 at each occurrence independently from each other comprise one, two or three six-atomic rings, preferably two or three six-atomic rings.

(343) Particularly preferred are the subformulae II-1, II-4, II-6, II-7, II-13, II-14, II-15, II-16, II-17 and II-18.

(344) Especially preferred are the subformulae IIa, IId, IIg, IIh, IIi, IIk and IIo, in particular the subformulae IIa and IIg, wherein L is in each occurrence independently of each other preferably F, Cl, CN, OH, NO.sub.2 or an optionally fluorinated alkyl, alkoxy or alkanoyl group with 1 to 7 C atoms, very preferably F, Cl, CN, OH, NO.sub.2, CH.sub.3, C.sub.2H.sub.5, OCH.sub.3, OC.sub.2H.sub.5, COCH.sub.3, COC.sub.2H.sub.5, COOCH.sub.3, COOC.sub.2H.sub.5, CF.sub.3, OCF.sub.3, OCHF.sub.2, OC.sub.2F.sub.5, in particular F, Cl, CN, CH.sub.3, C.sub.2H.sub.5, OCH.sub.3, COCH.sub.3 and OCF.sub.3, most preferably F, Cl, CH.sub.3, OCH.sub.3 and COCH.sub.3.

(345) Preferably R.sup.11 and R.sup.12, R.sup.21 and R.sup.22 and R.sup.31 and R.sup.32 in formula I are selected of H, F, Cl, CN, NO.sub.2, OCH.sub.3, COCH.sub.3, COC.sub.2H.sub.5, COOCH.sub.3, COOC.sub.2H.sub.5, CF.sub.3, C.sub.2F.sub.5, OCF.sub.3, OCHF.sub.2, and OC.sub.2F.sub.5, in particular of H, F, Cl, CN, OCH.sub.3 and OCF.sub.3, especially of H, F, CN and OCF.sub.3.

(346) Typical spacer groups (Sp) are for example (CH.sub.2).sub.o, (CH.sub.2CH.sub.2O).sub.pCH.sub.2CH.sub.2, with o being an integer from 5 to 40, in particular from 5 to 25, very preferably from 5 to 15, and p being an integer from 1 to 8, in particular 1, 2, 3 or 4.

(347) Especially media comprise one or more compounds of formula A-I wherein R.sup.11-MG.sup.11- and R.sup.12-MG.sup.12- are identical to each other.

(348) In another preferred embodiment of the present invention the media media comprise one or more to compounds of formula A-I wherein R.sup.11-MG.sup.11- and R.sup.12-MG.sup.12- are different from one another.

(349) Especially media comprise one or more compounds of formula A-II wherein R.sup.21-MG.sup.21- and R.sup.22-MG.sup.22- are identical to each other.

(350) In another preferred embodiment of the present invention the media media comprise one or more to compounds of formula A-II wherein R.sup.21-MG.sup.21- and R.sup.22-MG.sup.22- are different from one another.

(351) Especially media comprise one or more compounds of formula A-III wherein R.sup.31-MG.sup.31-X.sup.31 and R.sup.32-MG.sup.32-X.sup.32 are identical to each other.

(352) In another preferred embodiment of the present invention the media comprise one or more to compounds of formula A-III wherein R.sup.31-MG.sup.31-X.sup.31 and R.sup.32-MG.sup.32-X.sup.32 are different from one another.

(353) Especially preferred are compounds of formula A-III wherein the mesogenic groups MG.sup.31 and MG.sup.32 comprise one, two or three six-atomic rings very preferably are the mesogenic groups selected from formula II as listed below.

(354) For MG.sup.31 and MG.sup.32 in formula A-III are particularly preferred are the subformulae II-1, II-4, II-6, II-7, II-13, II-14, II-15, II-16, II-17 and II-18. In these preferred groups Z in each case independently has one of the meanings of Z.sup.1 as given in formula II. Preferably Z is COO, COO, CH.sub.2CH.sub.2, CC or a single bond.

(355) Very preferably the mesogenic groups MG.sup.31 and MG.sup.32 are selected from the formulae IIa to IIo and their mirror images.

(356) Particularly preferred for MG.sup.31 and MG.sup.23 are the subformulae IId, IIg, IIh, IIi, IIk and IIo, in particular the subformulae IId and IIk.

(357) In case of compounds with a non-polar group, R.sup.11, R.sup.12, R.sup.21, R.sup.22, R.sup.31 and R.sup.32 are preferably alkyl with up to 15 C atoms or alkoxy with 2 to 15 C atoms.

(358) If In case of compounds with an non-polar group, R.sup.11, R.sup.12, R.sup.21, R.sup.22, R.sup.31 or R.sup.32 is an alkyl or alkoxy radical, i.e. where the terminal CH.sub.2 group is replaced by O, this may be straight-chain or branched. It is preferably straight-chain, has 2, 3, 4, 5, 6, 7 or 8 carbon atoms and accordingly is preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, or octoxy, furthermore methyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy or tetradecoxy, for example.

(359) Oxaalkyl, i.e. where one CH.sub.2 group is replaced by O, is preferably straight-chain 2-oxapropyl (=methoxymethyl), 2-(=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3-, or 4-oxapentyl, 2-, 3-, 4-, or 5-oxahexyl, 2-, 3-, 4-, 5-, or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl or 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl, for example.

(360) Preferred spacer groups are pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, diethyleneoxyethylene, dimethyleneoxybutylene, pentenylene, heptenylene, nonenylene and undecenylene, for example.

(361) Especially preferred are inventive compounds of formula A-I and A-II and A-III wherein Sp.sup.1 respectively Sp.sup.2, respectively Sp.sup.3 is denoting alkylene with 5 to 15 C atoms. Straight-chain alkylene groups are especially preferred.

(362) Particularly preferred media according to the invention comprise at least one or more chiral dopants which themselves do not necessarily have to show a liquid crystalline phase and give good uniform alignment themselves.

(363) The compounds of formula C-II and their synthesis are described in WO 98/00428. Especially preferred is the compound CD-1, as shown in table D below. The compounds of formula C-III and their synthesis are described in GB 2 328 207.

(364) Especially preferred are chiral dopants with a high helical twisting power (HTP), in particular those disclosed in WO 98/00428.

(365) Further typically used chiral dopants are e.g. the commercially available R/S-5011, CD-1, R/S-811 and CB-15 (from Merck KGaA, Darmstadt, Germany).

(366) The above mentioned chiral compounds R/S-5011 and CD-1 and the (other) compounds of formulae C-I, C-II and C-III exhibit a very high helical twisting power (HTP), and are therefore particularly useful for the purpose of the present invention.

(367) The liquid crystalline medium preferably comprises preferably 1 to 5, in particular 1 to 3, very preferably 1 or 2 chiral dopants, preferably selected from the above formula C-II, in particular CD-1, and/or formula C-III and/or R-5011 or S-5011, very preferably the chiral compound is R-5011, S-5011 or CD-1.

(368) The amount of chiral compounds in the liquid crystalline medium is preferably from 1 to 20%, in particular from 1 to 15%, very preferably 1 to 10% by weight of the total mixture.

(369) Further preferred are liquid crystalline media comprising in component B one or more nematogens of formula B-I selected from the from the group of formulae B-I-1 to B-I-, preferably of formula B-I-2 and/or B-I-4, most preferably B-I-4

(370) ##STR00114## wherein the parameters have the meanings given above and preferably R.sup.B1 is alkyl, alkoxy, alkenyl or alkenyloxy with up to 12 C atoms, and L.sup.B1 and L.sup.B1 are independently H or F, preferably one is H and the other H or F and most preferably both are H.

(371) Further preferred are liquid crystalline media comprising in component B one or more nematogens of formula B-II selected from the from the group of formulae B-II-1 and B-II-2, preferably of formula B-II-2 and/or B-II-4, most preferably of formula B-II-1

(372) ##STR00115## wherein the parameters have the meanings given above and preferably R.sup.B21 and R.sup.B22 are independently alkyl, alkoxy, alkenyl or alkenyloxy with up to 12 C atoms, more preferably R.sup.B21 is alkyl and R.sup.B22 is alkyl, alkoxy or alkenyl and in formula B-II-1 most preferably alkenyl, in particular vinyl or 1-propenyl, and in formula B-II-2, most preferably alkyl.

(373) Further preferred are liquid crystalline media comprising in component B one or more nematogens of formula B-III, preferably of formula B-III-1

(374) ##STR00116## wherein the parameters have the meanings given above and preferably R.sup.B31 and R.sup.B32 are independently alkyl, alkoxy, alkenyl or alkenyloxy with up to 12 C atoms, more preferably R.sup.B31 is alkyl and R.sup.B32 is alkyl or alkoxy and most preferably alkoxy, and L.sup.B31 and L.sup.B32 are independently H or F, preferably one is F and the other H or F and most preferably both are F.

(375) The liquid crystal media according to the present invention may contain further additives in usual concentrations. The total concentration of these further constituents is in the range of 0.1% to 10%, preferably 0.1% to 6%, based on the total mixture. The concentrations of the individual compounds used each are preferably in the range of 0.1% to 3%. The concentration of these and of similar additives is not taken into consideration for the values and ranges of the concentrations of the liquid crystal components and compounds of the liquid crystal media in this application. This also holds for the concentration of the dichroic dyes used in the mixtures, which are not counted when the concentrations of the compounds respectively the components of the host medium are specified. The concentration of the respective additives is always given relative to the final doped mixture.

(376) The liquid crystal media according to the present invention consists of several compounds, preferably of 3 to 30, more preferably of 4 to 20 and most preferably of 4 to 16 compounds. These compounds are mixed in conventional way. As a rule, the required amount of the compound used in the smaller amount is dissolved in the compound used in the greater amount. In case the temperature is above the clearing point of the compound used in the higher concentration, it is particularly easy to observe completion of the process of dissolution. It is, however, also possible to prepare the media by other conventional ways, e.g. using so called pre-mixtures, which can be e.g. homologous or eutectic mixtures of compounds or using so called multi-bottle-systems, the constituents of which are ready to use mixtures themselves.

(377) Particularly preferred mixture concepts are indicated below: (the acronyms used are explained in Table A).

(378) The mixtures according to the invention preferably comprise as component A one or more compounds selected from the group of formulae A-I to A-III, preferably one or more compounds of formula A-I and one or more compounds of formula A-II, or one or more compounds of formula A-I and one or more compounds of formula A-III, or one or more compounds of formula A-II and one or more compounds of formula A-III, or, most preferred, one or more compounds of formula A-I and one or more compounds of formula A-II and one or more compounds of formula A-III, preferably in a total concentration of 90% or less, more preferably in the range from 60 to 90%, more preferably from 70 to 90%, and most preferably from 70 to 85% by weight of the total mixture, preferably these compounds are selected from one or more compounds of formula A-I (i.e. ether-linked dimers), preferably in a concentration of 40% or less, more preferably of 30% or less, based on component A, particularly preferred one or more compounds of formula A-I-1 to A-I-3, and especially preferred selected from the group of formulae N-GIGIGI-O-n-O-GGG-N, in particular N-GIGIGI-9-GGG-N, if present, preferably in concentration >5%, in particular from 10 to 30%, based on component A, and/or one or more compounds of formula A-II (i.e. methylene-linked dimers), preferably in a concentration of 60% or less, more preferably of 40% or less, in exceptional cases also 80 to 100% and in these cases preferably 90 to 100%, based on component A, particularly preferred one or more compounds of formula A-II-1 to A-II-4, and especially preferred selected from the group of formulae F-UIZIP-n-PZU-F, preferably FUIZIP-7-PZU-F and/or F-UIZP-9-PZU-F, preferably in concentrations of 5% more, in particular of 10 to 20%, based on component A, and/or one or more compounds of formula A-III (e.g. ester-linked dimers), preferably in a concentration of 80% or less, more preferably of 70% or less, based on component A, particularly preferred one or more compounds of formula A-III-1 to A-III-11, and especially preferred selected from the group of formulae F-PGI-ZI-n-Z-GP-F and F-PGI-ZI-n-Z-GP-F, preferably F-PGI-7-GP-F and/or F-PGI-9-GP-F and/or N-PGI-7-GP-N and/or N-PGI-9-GP-N, preferably in concentrations of 5% or more, in particular of 15 to 30% per compound, based on component A,
and/or as component B one or more compounds selected from the group of formulae B-I to B-III, preferably one or more compounds of formula B-I and one or more compounds of formula B-II, or one or more compounds of formula B-I and one or more compounds of formula B-III, or one or more compounds of formula B-II and one or more compounds of formula B-III, or one or more compounds of formula B-I and one or more compounds of formula B-II and one or more compounds of formula B-III, preferably in a total concentration of 40% or less, preferably in the range from 5 to 40%, more preferably from 10 to 30%, and most preferably from 10 to 20% by weight of the total mixture, preferably these compounds are selected from formulae B-I and/or B-II and/or B-III, and especially preferred selected from the group of formulae PP-n-N, PPP-n-N, CC-n-V, CC-n-V1, CEPGI-n-m, PY-n-Om, CCY-n-Om, CPY-n-Om and PYP-n-(O)m, preferably PP-5-N and/or PPP-3-N and/or CC-3-V and/or CC-4-V and/or CC-5-V and/or CC-3-V1 and/or CC-4-V1 and/or CEPGI-3-2 and/or CEPGI-5-2 and/or PY-3-O4, preferably in concentrations of 1% or more, in particular in the range from 2 to 10% per compound, based on the mixture as a whole,
and/or as component C one or more chiral compounds preferably in a total concentration in the range from 1 to 20%, in particular from 1 to 15%, very preferably 1 to 10% by weight of the total mixture, preferably these compounds are selected from formulae C-I, C-II, and C-III, in particular R-5011 or S-5011 or CD-1, especially preferred they comprise R-5011, S-5011 or CD-1, preferably in a concentration of 1% or more, in particular 1-20%, based on the mixture as a whole particularly preferred between 1 and 3%, in particular 2%, of R-5011 or S-5011 for displays in the ULH mode and 3.5 to 5.5%, in particular 4.5%, of R-5011 or S-5011 for displays in the USH mode, or a another chiral material in a concentration leading to the same cholesteric pitch as R-5011 or S-5011 in the preferred concentrations mentioned.

(379) Further preferred conditions for the mesogenic media are the following. They are fulfilled independently from one another and from the conditions mentioned above. Preferably, however, two, three four or more of these conditions and of the conditions mentioned above are fulfilled simultaneously.

(380) The media preferably comprise 40% or more, preferably 60% or more, based on component B, of bimesogens comprising exactly two rings in each of their mesogenic groups.

(381) The media preferably comprise one or more bimesogens comprising exactly three rings in each of their mesogenic groups and/or one or more bimesogens comprising exactly two rings in one of their mesogenic groups and comprising exactly three rings in their other mesogenic group.

(382) The media preferably comprise one or more non-symmetrical bimesogens, preferably in a total concentration of 50% or more, based on component A, preferably based on the mixture as a whole.

(383) A further, especially preferred condition is that the mixture has a low absolute value of , but preferably is dielectrically positive, especially at the temperatures between T(N,I) and 0.8 T(N,I). Preferably preferably is dielectrically positive at the temperatures from T(N,I) to the temperatures at which the ULH texture is still stable, preferably at least down to 40 C. Preferably the value of at these temperatures is 3 or less, more preferably in the range from 0 or more to 2 or less. In this respect it is not very important, if the value of becomes negative at lower temperatures, then it preferably is the in the range from between 1 or more to 0 or less.

(384) The bimesogenic compounds of formulae A-I, A-II and A-III and the liquid crystalline media comprising them can be used in liquid crystal displays, such as STN, TN, AMD-TN, temperature compensation, guest-host, phase change or surface stabilized or polymer stabilized cholesteric texture (SSCT, PSCT) displays, in particular in flexoelectric devices, in active and passive optical elements like polarizers, compensators, reflectors, alignment layers, color filters or holographic elements, in adhesives, synthetic resins with anisotropic mechanical properties, cosmetics, diagnostics, liquid crystal pigments, for decorative and security applications, in nonlinear optics, optical information storage or as chiral dopants.

(385) The compounds of formulae A-I and/or A-II and/or A-III and the mixtures obtainable thereof are particularly useful for flexoelectric liquid crystal display. Thus, another object of the present invention is a flexoelectric display comprising one or more compounds of formulae A-I and/or A-II and/or A-III, or comprising a liquid crystal medium comprising one or more compounds of formulae A-I and/or A-II and/or A-III.

(386) The inventive mesogenic mixtures comprising compounds of formulae A-I and/or A-II and/or A-III can be aligned in their cholesteric phase into different states of orientation by methods that are known to the expert, such as surface treatment or electric fields. For example, they can be aligned into the planar (Grandjean) state, into the focal conic state or into the homeotropic state. Inventive compounds of formula I comprising polar groups with a strong dipole moment can further be subjected to flexoelectric switching, and can thus be used in electrooptical switches or liquid crystal displays.

(387) The switching between different states of orientation according to a preferred embodiment of the present invention is exemplarily described below in detail for a sample of an inventive mixture comprising compounds of formulae A-I and/or A-II and/or A-III.

(388) The total concentration of all compounds in the media according to this application is 100%.

(389) According to this preferred embodiment, the sample is placed into a cell comprising two plane-parallel glass plates coated with electrode layers, e.g. ITO layers, and aligned in its cholesteric phase into a planar state wherein the axis of the cholesteric helix is oriented normal to the cell walls. This state is also known as Grandjean state, and the texture of the sample, which is observable e.g. in a polarization microscope, as Grandjean texture. Planar alignment can be achieved e.g. by surface treatment of the cell walls, for example by rubbing and/or coating with an alignment layer such as polyimide.

(390) A Grandjean state with a high quality of alignment and only few defects can further be achieved by heating the sample to the isotropic phase, subsequently cooling to the chiral nematic phase at a temperature close to the chiral nematic-isotropic phase transition, and rubbing the cell.

(391) In the planar state, the sample shows selective reflection of incident light, with the central wavelength of reflection depending on the helical pitch and the mean refractive index of the material.

(392) When an electric field is applied to the electrodes, for example with a frequency from 10 Hz to 1 kHz, and an amplitude of up to 12 V.sub.rms/m, the sample is being switched into a homeotropic state where the helix is unwound and the molecules are oriented parallel to the field, i.e. normal to the plane of the electrodes. In the homeotropic state, the sample is transmissive when viewed in normal daylight, and appears black when being put between crossed polarizers.

(393) Upon reduction or removal of the electric field in the homeotropic state, the sample adopts a focal conic texture, where the molecules exhibit a helically twisted structure with the helical axis being oriented perpendicular to the field, i.e. parallel to the plane of the electrodes. A focal conic state can also be achieved by applying only a weak electric field to a sample in its planar state. In the focal conic state the sample is scattering when viewed in normal daylight and appears bright between crossed polarizers.

(394) A sample of an inventive compound in the different states of orientation exhibits different transmission of light. Therefore, the respective state of orientation, as well as its quality of alignment, can be controlled by measuring the light transmission of the sample depending on the strength of the applied electric field. Thereby it is also possible to determine the electric field strength required to achieve specific states of orientation and transitions between these different states.

(395) In a sample of an inventive compound of formula I, the above described focal conic state consists of many disordered birefringent small domains. By applying an electric field greater than the field for nucleation of the focal conic texture, preferably with additional shearing of the cell, a uniformly aligned texture is achieved where the helical axis is parallel to the plane of the electrodes in large, well-aligned areas. In accordance with the literature on state of the art chiral nematic materials, such as P. Rudquist et al., Liq. Cryst. 23 (4), 503 (1997), this texture is also called uniformly-lying helix (ULH) texture. This texture is required to characterize the flexoelectric properties of the inventive compound.

(396) The sequence of textures typically observed in a sample of an inventive compound of formula I on a rubbed polyimide substrate upon increasing or decreasing electric field is given below:

(397) ##STR00117##

(398) Starting from the ULH texture, the inventive flexoelectric compounds and mixtures can be subjected to flexoelectric switching by application of an electric field. This causes rotation of the optic axis of the material in the plane of the cell substrates, which leads to a change in transmission when placing the material between crossed polarizers. The flexoelectric switching of inventive materials is further described in detail in the introduction above and in the examples.

(399) It is also possible to obtain the ULH texture, starting from the focal conic texture, by applying an electric field with a high frequency, of for example 10 kHz, to the sample whilst cooling slowly from the isotropic phase into the cholesteric phase and shearing the cell. The field frequency may differ for different compounds.

(400) The bimesogenic compounds of formula I are particularly useful in flexoelectric liquid crystal displays as they can easily be aligned into macroscopically uniform orientation, and lead to high values of the elastic constant k.sub.11 and a high flexoelectric coefficient e in the liquid crystal medium.

(401) The liquid crystal medium preferably exhibits a k.sub.11<110.sup.10 N, preferably <210.sup.11 N and a flexoelectric coefficient e>110.sup.11 C/m, preferably >110.sup.10 C/m.

(402) Apart from the use in flexoelectric devices, the inventive bimesogenic compounds as well as mixtures thereof are also suitable for other types of displays and other optical and electrooptical applications, such as optical compensation or polarizing films, color filters, reflective cholesterics, optical rotatory power and optical information storage.

(403) A further aspect of the present invention relates to a display cell wherein the cell walls exhibit hybrid alignment conditions. The term hybrid alignment or orientation of a liquid crystal or mesogenic material in a display cell or between two substrates means that the mesogenic groups adjacent to the first cell wall or on the first substrate exhibit homeotropic orientation and the mesogenic groups adjacent to the second cell wall or on the second substrate exhibit planar orientation.

(404) The term homeotropic alignment or orientation of a liquid crystal or mesogenic material in a display cell or on a substrate means that the mesogenic groups in the liquid crystal or mesogenic material are oriented substantially perpendicular to the plane of the cell or substrate, respectively.

(405) The term planar alignment or orientation of a liquid crystal or mesogenic material in a display cell or on a substrate means that the mesogenic groups in the liquid crystal or mesogenic material are oriented substantially parallel to the plane of the cell or substrate, respectively.

(406) A flexoelectric display according to a preferred embodiment of the present invention comprises two plane parallel substrates, preferably glass plates covered with a transparent conductive layer such as indium tin oxide (ITO) on their inner surfaces, and a flexoelectric liquid crystalline medium provided between the substrates, characterized in that one of the inner substrate surfaces exhibits homeotropic alignment conditions and the opposite inner substrate surface exhibits planar alignment conditions for the liquid crystalline medium.

(407) Planar alignment can be achieved e.g. by means of an alignment layer, for example a layer of rubbed polyimide or sputtered SiO.sub.x, that is applied on top of the substrate.

(408) Alternatively it is possible to directly rub the substrate, i.e. without applying an additional alignment layer. For example, rubbing can be achieved by means of a rubbing cloth, such as a velvet cloth, or with a flat bar coated with a rubbing cloth. In a preferred embodiment of the present invention rubbing is achieved by means of a at least one rubbing roller, like e.g. a fast spinning roller that is brushing across the substrate, or by putting the substrate between at least two rollers, wherein in each case at least one of the rollers is optionally covered with a rubbing cloth. In another preferred embodiment of the present invention rubbing is achieved by wrapping the substrate at least partially at a defined angle around a roller that is preferably coated with a rubbing cloth.

(409) Homeotropic alignment can be achieved e.g. by means of an alignment layer coated on top of the substrate. Suitable aligning agents used on glass substrates are for example alkyltrichlorosilane or lecithine, whereas for plastic substrate thin layers of lecithine, silica or high tilt polyimide orientation films as aligning agents may be used. In a preferred embodiment of the invention silica coated plastic film is used as a substrate.

(410) Further suitable methods to achieve planar or homeotropic alignment are described for example in J. Cognard, Mol. Cryst. Liq. Cryst. 78, Supplement 1, 1-77 (1981).

(411) By using a display cell with hybrid alignment conditions, a very high switching angle of flexoelectric switching, fast response times and a good contrast can be achieved.

(412) The flexoelectric display according to present invention may also comprise plastic substrates instead of glass substrates. Plastic film substrates are particularly suitable for rubbing treatment by rubbing rollers as described above.

(413) Another object of the present invention is that compounds of formula I, when added to a nematic liquid crystalline mixture, produce a phase below the nematic.

(414) Accordingly, the bimesogenic compounds of formula I according to the present invention allow the second nematic phase to be induced in nematic mixtures that do not show evidence of this phase normally. Furthermore, varying the amounts of compounds of formula I allow the phase behaviour of the second nematic to be tailored to the required temperature.

(415) Examples for this are given and the mixtures obtainable thereof are particularly useful for flexoelectric liquid crystal display. Thus, another object of the present invention is liquid crystal media comprising one or more compounds of formula I exhibiting a second nematic phase.

(416) Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following examples are, therefore, to be construed as merely illustrative and not limitative of the remainder of the disclosure in any way whatsoever.

(417) Unless the context clearly indicates otherwise, as used herein plural forms of the terms herein are to be construed as including the singular form and vice versa.

(418) Throughout the description and claims of this specification, the words comprise and contain and variations of the words, for example comprising and comprises, mean including but not limited to, and are not intended to (and do not) exclude other components.

(419) Throughout the present application it is to be understood that the angles of the bonds at a C atom being bound to three adjacent atoms, e.g. in a CC or CO double bond or e.g. in a benzene ring, are 120 and that the angles of the bonds at a C atom being bound to two adjacent atoms, e.g. in a CC or in a CN triple bond or in an allylic position CCC are 180, unless these angles are otherwise restricted, e.g. like being part of small rings, like 3-, 5- or 5-atomic rings, notwithstanding that in some instances in some structural formulae these angles are not represented exactly.

(420) It will be appreciated that variations to the foregoing embodiments of the invention can be made while still falling within the scope of the invention. Each feature disclosed in this specification, unless stated otherwise, may be replaced by alternative features serving the same, equivalent or similar purpose. Thus, unless stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

(421) All of the features disclosed in this specification may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. In particular, the preferred features of the invention are applicable to all aspects of the invention and may be used in any combination. Likewise, features described in non-essential combinations may be used separately (not in combination).

(422) 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.

(423) The following abbreviations are used to illustrate the liquid crystalline phase behavior of the compounds: K=crystalline; N=nematic; N2=second nematic; S=smectic; Ch=cholesteric; I=isotropic; Tg=glass transition. The numbers between the symbols indicate the phase transition temperatures in C.

(424) In the present application and especially in the following examples, the structures of the liquid crystal compounds are represented by abbreviations, which are also called acronyms. The transformation of the abbreviations into the corresponding structures is straight forward according to the following three tables A to C.

(425) All groups C.sub.nH.sub.2n+1, C.sub.mH.sub.2m+1, and C.sub.1H2.sub.l+1 are preferably straight chain alkyl groups with n, m and l C-atoms, respectively, all groups C.sub.nH.sub.2n, C.sub.mH.sub.2m and C.sub.lH.sub.2l are preferably (CH.sub.2).sub.n, (CH.sub.2).sub.m and (CH.sub.2).sub.l, respectively and CHCH preferably is trans-respectively E vinylene.

(426) Table A lists the symbols used for the ring elements, table B those for the linking groups and table C those for the symbols for the left hand and the right hand end groups of the molecules.

(427) Table D lists exemplary molecular structures together with their respective codes.

(428) TABLE-US-00011 TABLE A Ring Elements C D 0 A G G(Cl) G(1) U P DI AI GI GI(Cl) 0 GI(1) UI Y M N np n3f th th2f o2f 0 dh K MI NI n3fI thI th2fI o2fI KI L 0 F LI FI

(429) TABLE-US-00012 TABLE B Linking Groups n (CH.sub.2).sub.n n is an integer except 0 and 2 E CH.sub.2CH.sub.2 V CHCH T CC W CF.sub.2CF.sub.2 B CFCF Z COO ZI OCO X CFCH XI CHCF O CH.sub.2O OI OCH.sub.2 Q CF.sub.2O QI OCF.sub.2

(430) TABLE-US-00013 TABLE C End Groups Left hand side, used alone or Right hand side, used alone or in combination with others in combination with others -n- C.sub.nH.sub.2n+1 -n C.sub.nH.sub.2n+1 -nO- C.sub.nH.sub.2n+1O -nO OC.sub.nH.sub.2n+1 -V- CH.sub.2CH -V CHCH.sub.2 -nV- C.sub.nH.sub.2n+1CHCH -nV C.sub.nH.sub.2nCHCH.sub.2 -Vn- CH.sub.2CHC.sub.nH.sub.2n -Vn CHCHC.sub.nH.sub.2n+1 -nVm- C.sub.nH.sub.2n+1CHCHC.sub.mH.sub.2m -nVm C.sub.nH.sub.2nCHCHC.sub.mH.sub.2m+1 -N- NC -N CN -S- SCN -S NCS -F- F -F F -CL- Cl -CL Cl -M- CFH.sub.2 -M CFH.sub.2 -D- CF.sub.2H -D CF.sub.2H -T- CF.sub.3 -T CF.sub.3 -MO- CFH.sub.2O -OM OCFH.sub.2 -DO- CF.sub.2HO -OD OCF.sub.2H -TO- CF.sub.3O -OT OCF.sub.3 -A- HCC -A CCH -nA- C.sub.nH.sub.2n+1CC -An CCC.sub.nH.sub.2n+1 -NA- NCCC -AN CCCN Left hand side, used in Right hand side, used in combination with others only combination with others only - . . . n . . . - C.sub.nH.sub.2n - . . . n . . . C.sub.nH.sub.2n - . . . M . . . - CFH - . . . M . . . CFH - . . . D . . . - CF.sub.2 - . . . D . . . CF.sub.2 - . . . V . . . - CHCH - . . . V . . . CHCH - . . . Z . . . - COO - . . . Z . . . COO - . . . ZI . . . - OCO - . . . ZI . . . OCO - . . . K . . . - CO - . . . K . . . CO - . . . W . . . - CFCF - . . . W . . . CFCF
wherein n and m each are integers and three points . . . indicate a space for other symbols of this table.

(431) Preferably the liquid crystalline media according to the present invention comprise, besides the compound(s) of formula I one or more compounds selected from the group of compounds of the formulae of the following table.

(432) TABLE-US-00014 TABLE D F-PGI-O-n-O-GP-F F-PG-O-n-O-GIP-F N-PP-O-n-O-GU-F F-PGI-O-n-O-PP-N R-5011 respectively S-5011 CD-1 PP-n-N 0 PPP-n-N CC-n-V CPP-n-m CEPGI-n-m CPPC-n-m PY-n-Om CCY-n-Om CPY-n-Om PPY-n-Om F-UIGI-ZI-n-Z-GU-F 0 N-PGI-ZI-n-Z-GP-N F-PGI-ZI-n-Z-GP-F N-GIGIGI-n-GGG-N N-PGIUI-n-UGP-N N-GIUIGI-n-GUG-N N-GIUIP-n-PUG-N N-PGI-n-GP-N N-PUI-n-UP-N N-UIUI-n-UU-N N-GIGI-n-GG-N 0 F-UIGI-n-GU-F UIP-n-PU N-PGI-n-GP-N N-PGI-ZI-n-Z-GP-N F-PGI-ZI-n-Z-GP-F F-UIGI-ZI-n-Z-GU-F F-PGI-ZI-n-Z-PP-N N-GIGI-n-GG-N N-PUI-n-UP-N N-PUI-n-UP-N 0 F-UIP-ZI-n-Z-PZU-F F-PGI-ZI-n-Z-PUU-N F-PGI-ZI-n-Z-GUU-N N-PGI-ZI-n-Z-PUU-N N-PGI-ZI-n-Z-GUU-N F-PGI-n-Z-PUU-N F-PGI-n-Z-GUU-N F-PGI-ZI-n-PUU-N F-PGI-ZI-n-GUU-N

Mixture Examples

Mixture Example 1: Mixture M1

(433) TABLE-US-00015 Composition Compound No. Abbreviation Conc./% 1 R-5011 2.0 2 F-PGI-ZI-7-Z-PP-N 29.0 3 F-PGI-ZI-9-Z-PUU-N 29.0 4 N-PGI-ZI-7-Z-GP-N 15.0 5 F-UIZIP-7-PZU-F 15.0 6 CC-3-V 5.0 7 PPP-3-N 5.0 100.0

(434) This mixture is particularly well suitable for the ULH-mode. It is investigated in antiparallel rubbed cells with polyimide orientation layers (e.g. AL3046) of appropriate cell gap, typically of 5.4 m.

(435) It has a range of the (chiral) nematic phase from 20 C. to 90 C. The cholesteric pitch (P) is 300 nm and the flexoelectric ratio (e/K) is 3.6 V.sup.1, both determined at a temperature of 35 C. The electric field has been varied from 0 V/m) to about 3.0 V/m), leading to a tilt angle () increasing from 0 to about 27.5 over that range of electric fields.

(436) It has a double response time for switching on (.sub.on) of about 1 ms at an electric field of 3.0 V/m and of about 0.5 ms at an electric field of 3.5 V/m. I.e. the sum of the response times (.sub.on,driven+.sub.off,driven) is below 1 ms at electrical fields of 3.0 V/m and more. The sum of the response times for switching off by relaxation only (.sub.on,driven+.sub.off,non-driven) is below 5 ms at electrical fields of 3.0 V/m and more. Here the double of the response time for switching on (.sub.on) is the decisive feature for several applications, as the mixture can be actively switched on as well as off.

(437) The transmission under crossed polarizers of this mixture relative to an empty cell (for reference of 100%) has a maximum value switched at an electric field of 3.0 V/m with 60%. At an electric field of 3.5 V/m the relative transmission of this mixture is about 58%. Probably the maximum the transmission is limited by the insufficient alignment of the helix: some of the ULH is at an undesired angle to the direction required.

Mixture Example 2 and Comparative Mixture Example 2

Comparative Mixture Example 2: Mixture C2

(438) TABLE-US-00016 Composition Compound No. Abbreviation Conc./% 1 R-5011 2.0 2 F-GIGI-ZI-5-PP-N 24.5 3 F-GIGI-5-Z-PGP-N 24.5 4 N-PGI-5-Z-GP-N 24.5 5 F-GIGI-5-Z-PP-N 24.5 100.0

(439) This comparative mixture is investigated as described under mixture example 1.

(440) It has a range of the (chiral) nematic phase from at least 35 C. to 97 C. The flexoelectric ratio (e/K) is 13.9 V.sup.1 at a temperature of 37 C., 7.6 V.sup.1 at a temperature of 40 C., 4.9 V.sup.1 at a temperature of 50 C. and still 4.3 V.sup.1 at a temperature of 60 C.

Mixture Example 2: Mixture M2

(441) TABLE-US-00017 Composition Compound No. Abbreviation Conc./% 1 R-5011 1.8 2 N-PGI-ZI-9-Z-PP-N 11.8 3 TO-PGI-ZI-9-Z-PP-N 6.1 4 F-PGI-ZI-7-Z-PP-N 20.1 5 F-PGI-ZI-9-Z-PU-N 12.8 6 F-PGI-ZI-9-Z-PUU-N 9.8 7 F-UIGI-ZI-9-GP-N 18.5 8 F-PGI-Z-5-Z-GP-N 18.6 100.0

(442) The resultant mixture (M2) is investigated as described under mixture example 1. It has a range of the (chiral) nematic phase from below 20 C. up to 93 C. The flexoelectric ratio (e/K) is 4.33 V.sup.1 at a temperature of 35 C. and 3.02 V.sup.1 at a temperature of 57 C. (0.9T(N,I)).

Mixture Example 3: Mixture M3

(443) TABLE-US-00018 Composition Compound/Mixure No. Abbreviation Conc./% 1 R-5011 2.0 2 F-PGI-ZI-9-Z-PUU-N 10.0 3 N-PGI-9-GP-N 8.0 4 N-UIUI-9-UU-N 10.0 5 F-PGI-7-PG-F 8.0 6 F-PGI-ZI-9-Z-GP-F 8.0 7 F-PGI-ZI-9-GGP-N 10.0 8 N-PGI-ZI-9-GGP-N 6.0 9 F-GIGI-ZI-9-GPG-F 6.0 10 N(1) * 20.0 100.0
wherein N(1) is the menatic mixture

(444) TABLE-US-00019 Composition Compound No. Abbreviation Conc./% 1 PY-3-O2 14.5 2 CCY-3-O2 3.5 3 CCY-4-O2 13.5 4 CPY-2-O2 11.0 5 CPY-3-O2 11.0 6 CC-3-V 29.0 7 CPP-3-2 13.5 5 CPPC-3-3 4.0 100.0
which has the following physical properties:
T.sub.N,I=103.6 C;
n=0.124 @25 C;
=2.8 @25 C; and
.sub.1=114 mPa.Math.s.

(445) The resultant mixture (M3) is investigated as described under mixture example 1. It has a range of the (chiral) nematic phase up to 77 C. The cholesteric pitch (P) is 274 nm and the flexoelectric ratio (e/K) is 3.3 V.sup.1 at a temperature of (0.9T(N,I). The total response time (.sub.on,driven+.sub.off,driven) is 2.2 ms.

Mixture Example 4: Mixture M4

(446) TABLE-US-00020 Composition Compound/Mixure No. Abbreviation Conc./% 1 F-PGI-ZI-9-Z-PUU-N 16.2 2 F-PGI-ZI-9-Z-PP-N 10.2 3 F-PGI-ZI-9-Z-PU-N 10.2 4 F-PGI-ZI-7-Z_PP-N 11.9 5 N-GIGI-ZI-9-Z-GG-N 6.8 6 F-UIGI-ZI-9-Z-GP-N 12.8 7 N-GIGI-9-GG-N 8.5 8 N-UIUI-9-UU-N 6.8 9 N(1) * 5.1 10 N(2) * 7.7 100.0
wherein N(1) is the menatic mixture described above and N(2) is the menatic mixture

(447) TABLE-US-00021 Composition Compound No. Abbreviation Conc./% 1 CC-5-V 20.0 2 PP-1-2V1 20.0 3 PGP-1-2V 20.0 4 PGP-2-2V 20.0 5 PGP-3-2V 20.0 100.0

(448) This mixture M4 has a birefringence (n) of 0.0838.

(449) Then 10% of the compound N-PGI-ZI-9-ZGGP-N are added to said mixture M4 and the resultant mixture M4.1 has an increased birefringence of 0.845.

(450) Generally the use of a nematic compound helps to reduce the viscosity of the media and hence to improve the response times. This is illustrated by the following example.

Mixture Example 5: Mixture M5

(451) TABLE-US-00022 Composition Compound/Mixure No. Abbreviation Conc./% 1 F-PGI-ZI-9-Z-PU-N 20.0 2 F-PGI-ZI-9-Z-PUU-N 15.0 03 N-UIUI-ZI-9-Z-UU-N 20.0 4 N-GIZIP-7-PZG-N 15.0 5 F-PGI-ZI-9-Z-PP-N 15.0 6 N-PGI-ZI-9-Z-GP-N 15.0 100.0

(452) To 80% of this mixture (M5) alternatively 20% of one each of three different nematic mixtures is added. The first nematic mixture is E7, having a dielectric anisotropy () of +14, available from Merck. The second one is a mixture consisting of 40% of the nematic mixture N1 and 60% of the nematic mixture N2, both mentioned above, having of 0, and the third one is the following mixture N3, having of 9.

(453) 10% of the following mixture (mixture N1),

(454) TABLE-US-00023 Composition Compound No. Abbreviation Conc./% 1 Y-4O-O4 12.0 2 CY-3-O2 16.0 3 CZY3-O2 10.0 4 CZY-5-O2 10.5 5 CCY-3-O1 8.0 6 CCY-3-O1 8.0 7 CLY-3-O2 8.0 8 CPY-2-O2 10.0 9 CPY-3-O2 01.0 10 CPTY-3-O3 8.0 100.0
which has the following physical properties:
=9 @20 C.

(455) Upon addition of the nematic mixtures the resultant mixtures M5.1 to M5.3 all show reduced viscosity, which leads to faster switching. At the same tome, however, the flexoelastic ratio is decreased, albeoit least when a nematic mixture with a negative dielectric anisotropy is added, i. in case of adding nematic mixture N3 leading to M5.3.