Patent Description:
Liquid-crystalline media have a been used for many years in electro-optical displays (liquid crystal displays: LCDs) in order to display information. More recently, however, liquid-crystalline media have also been proposed for use in components for microwave technology, such as, for example, in <CIT> and in <CIT>).

<NPL>, describe the corresponding properties of the known liquid-crystal mixture E7 (Merck KGaA, Germany).

<CIT> describes the use of liquid-crystal media in microwave technology, inter alia in phase shifters. Therein, liquid-crystalline media with respect to their properties in the corresponding frequency range have been discussed and liquid-crystalline media based on mixtures of mostly aromatic nitriles and isothiocyanates have been shown.

In <CIT> and <CIT>, mixtures are described that completely consist of isothiocyanate compounds.

Fluorine atoms are commonly used in mesogenic compounds to introduce polarity. Especially in combination with a terminal NCS group high dielectric anisotropy values can be achieved.

However, compositions available for the use in microwave applications are still afflicted with several disadvantages. It is required to improve these media with respect to their general physical properties, the shelf life and the stability under operation in a device.

In view of the multitude of different parameters which have to be considered and improved for the development of liquid crystalline media for microwave application it is desirable to have a broader range of possible mixture components for the development of such liquid-crystalline media.

An object of the present invention is to provide a compound for the use in liquid crystalline media with improved properties relevant for the application in the microwave range of the electromagnetic spectrum.

To solve the problem, a compound selected from the compounds of the formulae N-<NUM> to N-<NUM> shown below is provided and a liquid crystalline medium comprising the compound.

The present invention thus relates to a compound selected from the compounds of the formulae N-<NUM> to N-<NUM> as in claim <NUM> and defined below.

Also described herein is a compound of formula N
<CHM>
in which.

Further described is a compound of formula NH
<CHM>
in which the occurring groups and parameters have the meanings given above for formula N, and to a process for the synthesis of compounds of formula N from compounds of formula NH.

The present invention further relates to a liquid-crystalline medium comprising a compound selected from the compounds of the formulae N-<NUM> to N-<NUM> and to the use of a liquid-crystalline medium comprising a compound selected from the compounds of the formulae N-<NUM> to N-<NUM> in a component for high-frequency technology.

According to another aspect of the present invention there is provided a component and a device comprising said component, both operable in the microwave region of the electromagnetic spectrum. Preferred components are phase shifters, varactors, wireless and radio wave antenna arrays, matching circuits and adaptive filters.

Preferred embodiments of the present invention are subject-matter of the dependent claims or can also be taken from the description.

Surprisingly, it has been found that it is possible to achieve liquid-crystalline media having excellent stability and at the same time a high dielectric anisotropy, suitably fast switching times, a suitable, nematic phase range, high tunability and low dielectric loss, by using compound selected from the compounds of the formulae N-<NUM> to N-<NUM> in liquid-crystalline media.

The media according to the present invention are distinguished by a high clearing temperature, a broad nematic phase range and excellent low-temperature stability (LTS). As a result, devices containing the media are operable under extreme temperature conditions.

The media are further distinguished by high values of the dielectric anisotropy and low rotational viscosities. As a result, the threshold voltage, i.e. the minimum voltage at which a device is switchable, is very low. A low operating voltage and low threshold voltage is desired in order to enable a device having improved switching characteristics and high energy efficiency. Low rotational viscosities enable fast switching of the devices according to the invention.

It particular, a medium comprising a compound according to the invention is distinguished by a very low dielectric loss.

These properties as a whole make the media particularly suitable for use in components and devices for high-frequency technology and applications in the microwave range, in particular devices for shifting the phase of microwaves, tunable filters, tunable metamaterial structures, and electronic beam steering antennas (e.g. phased array antennas).

Herein, "high-frequency technology" means applications of electromagnetic radiation having frequencies in the range of from <NUM> to <NUM> THz, preferably from <NUM> to <NUM>, more preferably <NUM> to <NUM>, particularly preferably from about <NUM> to <NUM>.

As used herein, halogen is F, Cl, Br or I, preferably F or Cl, particularly preferably F.

Herein, alkyl is straight-chain or branched and has <NUM> to <NUM> C atoms, is preferably straight-chain and has, unless indicated otherwise, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM> C atoms and is accordingly preferably methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl or n-heptyl.

Herein, branched alkyl is preferably isopropyl, s-butyl, isobutyl, isopentyl, <NUM>-methylbutyl, <NUM>-methylhexyl or <NUM>-ethylhexyl.

Herein, an alkoxy radical is straight-chain or branched and contains <NUM> to <NUM> C atoms. It is preferably straight-chain and has, unless indicated otherwise, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM> C atoms and is accordingly preferably methoxy, ethoxy, n-propoxy, n-butoxy, n-pentoxy, n-hexoxy or n-heptoxy.

Herein, an alkenyl radical is preferably an alkenyl radical having <NUM> to <NUM> C atoms, which is straight-chain or branched and contains at least one C-C double bond. It is preferably straight-chain and has <NUM> to <NUM> C atoms. Accordingly, it is preferably vinyl, prop-<NUM>- or -<NUM>-enyl, but-<NUM>-, -<NUM>- or -<NUM>-enyl, pent-<NUM>-, -<NUM>-, -<NUM>- or -<NUM>-enyl, hex-<NUM>-, -<NUM>-, -<NUM>-, -<NUM>-or -<NUM>-enyl, hept-<NUM>-, -<NUM>-, -<NUM>-, -<NUM>-, -<NUM>- or -<NUM>-enyl. If the two C atoms of the C-C double bond are substituted, the alkenyl radical can be in the form of E and/or Z isomer (trans/cis). In general, the respective E isomers are preferred. Of the alkenyl radicals, prop-<NUM>-enyl, but-<NUM>- and -<NUM>-enyl, and pent-<NUM>- and -<NUM>-enyl are particularly preferred.

Herein, alkynyl is taken to mean an alkynyl radical having <NUM> to <NUM> C atoms, which is straight-chain or branched and contains at least one C-C triple bond. <NUM>- and <NUM>-propynyl and <NUM>-, <NUM>- and <NUM>-butynyl are preferred.

In case RF denotes a fluorinated alkyl-, alkoxy-, alkenyl or alkenyloxy radical it can be branched or unbranched. Preferably it is unbranched, mono- poly or perfluorinated, preferably perfluorinated and has <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM> C atoms, in case of alkenyl <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM> C atoms.

RP preferably denotes CN, NCS, Cl, F, -(CH<NUM>)n-CH=CF<NUM>, -(CH<NUM>)n-CH=CHF, -(CH<NUM>)n-CH=Cl<NUM>, -CnF2n+<NUM>, -(CF<NUM>)n-CF<NUM>H, -(CH<NUM>)n-CF<NUM>, -(CH<NUM>)n-CHF<NUM>, -(CH<NUM>)nCH<NUM>F, -CH=CF<NUM>,-O(CH<NUM>)n-CH=CF<NUM>, -O(CH<NUM>)nCHCl<NUM>, -OCnF2n+<NUM>, -O(CF<NUM>)n-CF<NUM>H, -O(CH<NUM>)nCF<NUM>, -O(CH<NUM>)n-CHF<NUM>, -O(CF)nCH<NUM>F, -OCF=CF<NUM>, -SCnF2n+<NUM>, -S(CF)n-CF<NUM>, wherein n is an integer from <NUM> to <NUM>.

The compounds of the general formula N are prepared by methods known per se, as described in the literature (for example in the standard works, such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), to be precise under reaction conditions which are known and are suitable for said reactions. Use can be made here of variants which are known per se, but are not mentioned here in greater detail.

If desired, the starting materials can also be formed in situ by not isolating them from the reaction mixture, but instead by immediately reacting them further into the compounds of the general formula N.

Preferred synthetic pathways towards compounds according to the invention are exemplified in the schemes below, and are further illustrated by means of the working examples. Suitable syntheses are also published for example in <NPL> and can be adapted to the particular desired compounds of the general formula N by choice of suitable starting materials.

Preferred intermediates are <NUM>-bromopyrimidin-<NUM>-amine, <NUM>-bromo-<NUM>-chloro-<NUM> pyridinamine, <NUM>-bromo-<NUM>-fluoro-<NUM> pyridinamine, <NUM>-bromo-<NUM>-fluoro-<NUM>-pyridinamine, <NUM>-bromo-<NUM>,<NUM>-dichloro-<NUM>-pyridinamine and the like, all described in the literature or accessible by synthetic procedures known to the skilled person, which can be reacted to give compounds of the formula N or NH for example by cross coupling reactions commonly known as Suzuki, Stille, Sonogashira reactions, and the like. Preferred pathways are exemplified in schemes <NUM> and <NUM>, in which the groups and parameters have the meanings defined in claim <NUM>. <CHM>
<CHM>.

Preferred reagents for the process according to the invention for the transformation of compounds of the formula N into compounds of the formula N (scheme <NUM>) are carbon disulfide, thiophosgene, thiocarbonyl diimidazole, di-<NUM>-pyridyl thionocarbonate, bis(dimethylthiocarbamoyl) disulfide, dimethylthiocarbamoyl chloride and phenyl chlorothionoformate, very preferably thiophosgene.

The reactions described above and below should only be regarded as illustrative. The person skilled in the art can carry out corresponding variations of the syntheses described and also follow other suitable synthetic routes in order to obtain compounds of the formula N.

According to a first aspect of the present invention there are provided compounds of formula N in which RN denotes H, alkyl or alkoxy having <NUM> to <NUM> C atoms, or alkenyl, alkenyloxy or alkoxyalkyl having <NUM> to <NUM> C atoms, in which one or more CH<NUM>-groups may be replaced by
<CHM>
preferably alkyl having <NUM> to <NUM> C atoms.

According to a second aspect of the present invention there are provided compounds of formula N in which the group RN denotes RP, where RP denotes halogen, CN, NCS, RF, RF-O- or RF-S-, and wherein RF denotes fluorinated alkyl or fluorinated alkenyl having up to <NUM> C atoms, preferably perfluorinated alkyl or perfluorinated alkenyl having up to <NUM> C atoms, very preferably CF<NUM> or OCF<NUM>, in particular OCF<NUM>.

According to the invention, the compound is selected from the compounds of the formulae N-<NUM> to N-<NUM>, preferably from the compounds of the formulae N-<NUM> and N-<NUM>:
<CHM>
<CHM>
<CHM>
in which RN, ZN1, ZN2,
<CHM>
have the meanings given above for formula N, Y<NUM> and Y<NUM>, identically or differently, denote H, F, Cl or CH<NUM>, preferably H, F or Cl, and t is <NUM> or <NUM>.

In the compounds of formula N or N-<NUM> or N-<NUM>,
<CHM>
independently of one another, preferably denote
<CHM>
<CHM>
wherein
<CHM>
alternatively denotes
<CHM>
<CHM>
and
L<NUM> and L<NUM>, identically or differently, denote H, F, Cl or straight chain or branched or cyclic alkyl or alkenyl each having <NUM>, <NUM>, <NUM>, or <NUM> to <NUM> C atoms, respectively.

In the compounds of formula N or N-<NUM> or N-<NUM>, ZN1 and ZN2, identically or differently, preferably denote -C≡C- or a single bond.

In formula N, the group
<CHM>
is preferably selected from the following groups:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

In an embodiment, the compounds of formula N contain a partial structure
<CHM>
selected from the following groups:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

In a preferred embodiment of the present invention, the compounds of formula N-<NUM> and N-<NUM> are selected from the compounds of the formulae N-<NUM>-<NUM> to N-<NUM>-<NUM> and N-<NUM>-<NUM> to N-<NUM>-<NUM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which.

In a preferred embodiment, in the compounds of formula N and its sub-formulae, one or both of Y<NUM> and Y<NUM> denote H, preferably both.

In another preferred embodiment, in the compounds of formula N and its sub-formulae both of Y<NUM> and Y<NUM> denote F.

In a preferred embodiment of the present invention the medium comprises one or more compounds selected from the group of compounds of the formulae I, II and III,
<CHM>
<CHM>
<CHM>
in which.

more preferably
<CHM>
denotes
<CHM>
<CHM>
denotes
<CHM>
in particular
<CHM>
<CHM>
denotes
<CHM>
in particular
<CHM>.

In the compounds of the formulae I, II and III, RL preferably denotes H.

In another preferred embodiment, in the compounds of formulae I, II and III, one or two groups RL , preferably one group RL is different from H.

In a preferred embodiment of the present invention, the compounds of formula I are selected from the group of compounds of the formulae I-<NUM> to I-<NUM>:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which.

The media preferably comprise one or more compounds of formula I-<NUM>, which are preferably selected from the group of the compounds of the formulae I-1a to I-1d, preferably of formula I-1b:
<CHM>
<CHM>
<CHM>
<CHM>
in which R<NUM> has the meaning indicated above for formula I and preferably denotes unfluorinated alkyl having <NUM> to <NUM> C atoms or unfluorinated alkenyl having <NUM> to <NUM> C atoms.

The media preferably comprise one or more compounds of formula I-<NUM>, which are preferably selected from the group of the compounds of the formulae I-2a to I-2e, preferably of formula I-2c:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which R<NUM> has the meaning indicated above for formula I and preferably denotes unfluorinated alkyl having <NUM> to <NUM> C atoms or unfluorinated alkenyl having <NUM> to <NUM> C atoms.

The media preferably comprise one or more compounds of formula I-<NUM>, which are preferably selected from the group of the compounds of the formulae I-3a to I-3d , particularly preferably of formula I-3b:
<CHM>
<CHM>
<CHM>
<CHM>
in which R<NUM> has the meaning indicated above for formula I and preferably denotes unfluorinated alkyl having <NUM> to <NUM> C atoms or unfluorinated alkenyl having <NUM> to <NUM> C atoms.

The media preferably comprise one or more compounds of formula I-<NUM>, which are preferably selected from the group of the compounds of the formulae I-4a to I-4e, particularly preferably of formula I-4b:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which R<NUM> has the meaning indicated above for formula I and preferably denotes unfluorinated alkyl having <NUM> to <NUM> C atoms or unfluorinated alkenyl having <NUM> to <NUM> C atoms.

The media preferably comprise one or more compounds of formula I-<NUM>, which are preferably selected from the group of the compounds of the formulae I-5a to I-5d, particularly preferably of formula I-5b:
<CHM>
<CHM>
<CHM>
<CHM>
in which R<NUM> has the meaning indicated above for formula I and preferably denotes unfluorinated alkyl having <NUM> to <NUM> C atoms or unfluorinated alkenyl having <NUM> to <NUM> C atoms.

The media preferably comprise one or more compounds of formula II, which are preferably selected from the group of the compounds of the formulae II-<NUM> to <NUM>-<NUM>, preferably selected from the group of the compounds of the formulae II-<NUM> and II-<NUM>:
<CHM>
<CHM>
<CHM>.

The compounds of formula II-<NUM> are preferably selected from the group of the compounds of the formulae II-1a to II-1e:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which.

The compounds of formula II-<NUM> are preferably selected from the group of the compounds of the formulae II-2a and II-2b:
<CHM>
<CHM>
in which.

The compounds of formula II-<NUM> are preferably selected from the group of the compounds of the of formulae II-3a to II-3d:
<CHM>
<CHM>
<CHM>
<CHM>
in which.

The compounds of formula III are preferably selected from the group of the compounds of the formulae III-<NUM> to III-<NUM>, more preferably of the formulae selected from the group of the compounds of the formulae III-<NUM>, III-<NUM>, III-<NUM> and III-<NUM>, and particularly preferably of formula III-<NUM>:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which.

and one of
<CHM>
denotes
<CHM>
<CHM>
preferably
<CHM>
and the others, independently of one another, denote
<CHM>
<CHM>
or
<CHM>
preferably
<CHM>
or
<CHM>
more preferably
<CHM>
where
<CHM>
alternatively denotes
<CHM>
and preferably.

The compounds of formula III-<NUM> are preferably selected from the group of the compounds of the formulae III-1a to III-<NUM>, more preferably selected from the group of the compounds of the formulae III-1a, III-1b, III-<NUM> and III-<NUM>, particularly preferably of formula Ill-1b and/or III-<NUM>:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which.

The compounds of formula III-<NUM> are preferably compounds of formula III-2a to III-<NUM>, very preferably III-2b and/or III-2j:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which.

The compounds of formula III-<NUM> are preferably selected from the compounds of formula III-5a:
<CHM>.

In a preferred embodiment, the media according to the invention comprise one or more compounds selected from the group of compounds of the formulae IIA-<NUM>-<NUM> to IIA-<NUM>-<NUM>, very preferably IIA-<NUM>-<NUM> or IIA-<NUM>-<NUM>:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which.

and from which the compounds of formula II-<NUM> are excluded.

Additionally, the liquid-crystalline media according to the present invention in a certain embodiment, which may be the same or different from the previous preferred embodiments preferably comprise one or more compounds of formula IV,
<CHM>
in which
<CHM>
denotes
<CHM>
<CHM>.

In a preferred embodiment of the present invention, the liquid-crystal medium additionally comprises one or more compounds selected from the group of compounds of the formulae V, VI, VII, VIII and IX:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which.

In a preferred embodiment of the present invention, the liquid-crystal medium comprises one or more compounds of the formula V, preferably selected from the group of the compounds of the formulae V-<NUM> to V-<NUM>, preferably of the formulae V-<NUM> and/or V-<NUM> and/or V-<NUM>, preferably of the formulae V-<NUM> and V-<NUM>:
<CHM>
<CHM>
<CHM>
in which the occurring groups have the respective meanings indicated above for formula V and preferably.

The compounds of the formula V-<NUM> are preferably selected from the group of the compounds of the formulae V-1a to V-1d, preferably V-1c and V-1d :
<CHM>
<CHM>
<CHM>
<CHM>
in which the parameters have the respective meanings indicated above for formula V-<NUM> and in which.

The compounds of the formula V-<NUM> are preferably selected from the group of the compounds of the formulae V-2a to V-2e and/or from the group of the compounds of the formulae V-2f and V-<NUM>:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

The compounds of the formula V-<NUM> are preferably compounds of the formula V-3a:
<CHM>
in which the parameters have the respective meanings indicated above for formula V-<NUM> and in which preferably.

The compounds of the formula V-1a are preferably selected from the group of the compounds of the formulae V-1a-<NUM> and V-1a-<NUM>:
<CHM>
<CHM>
in which.

The compounds of the formula V-1b are preferably compounds of the formula V-1b-<NUM>:
<CHM>
in which.

The compounds of the formula V-1c are preferably selected from the group of the compounds of the formulae V-1c-<NUM> to V-1c-<NUM>, particularly preferably selected from the group of the compounds of the formulae V-1c-<NUM> and V-1c-<NUM>:
<CHM>
<CHM>
<CHM>
<CHM>
in which.

The compounds of the formula V-1d are preferably selected from the group of the compounds of the formulae V-1d-<NUM> and V-1d-<NUM>, particularly preferably the compound of the formula V-1d-<NUM>:
<CHM>
<CHM>
in which.

The compounds of the formula V-2a are preferably selected from the group of the compounds of the formulae V-2a-<NUM> and V-2a-<NUM>, particularly preferably the compounds of the formula V-2a-<NUM>:
<CHM>
<CHM>
in which.

Preferred combinations of R<NUM> with R<NUM>, in particular in the case of formula V-2a-<NUM>, are (CnH2n+<NUM> and CmH<NUM>+<NUM>), (CnH2n+<NUM> and O-CmH<NUM>+<NUM>), (CH<NUM>=CH-(CH<NUM>)Z and CmH<NUM>+<NUM>), (CH<NUM>=CH-(CH<NUM>)Z and O-CmH<NUM>+<NUM>) and (CnH2n+<NUM> and (CH<NUM>)Z-CH=CH<NUM>).

Preferred compounds of the formula V-2b are the compounds of the formula V-2b-<NUM>:
<CHM>
in which.

The preferred combination of R<NUM> with R<NUM> here is, in particular, CnH2n+<NUM> and CmH<NUM>+<NUM>. Preferred compounds of the formula V-2c are the compounds of the formula V-2c-<NUM>:
<CHM>
in which.

The preferred combination of (R<NUM> and R<NUM>) here is, in particular, (CnH2n+<NUM> and CmH<NUM>+<NUM>).

Preferred compounds of the formula V-2d are the compounds of the formula V-2d-<NUM>:
<CHM>
in which.

Preferred compounds of the formula V-2e are the compounds of the formula V-2e-<NUM>:
<CHM>
in which.

The preferred combination of (R<NUM> and R<NUM>) here is, in particular, (CnH2n+<NUM> and O-CmH<NUM>+<NUM>).

Preferred compounds of the formula V-2f are the compounds of the formula V-2f-<NUM>:
<CHM>
in which.

The preferred combinations of (R<NUM> and R<NUM>) here are, in particular, (CnH2n+<NUM> and
CmH<NUM>+<NUM>) and (CnH2n+<NUM> and O-CmH<NUM>+<NUM>), particularly preferably (CnH2n+<NUM> and CmH<NUM>+<NUM>).

Preferred compounds of the formula V-<NUM> are the compounds of the formula V-<NUM>-<NUM>:
<CHM>
in which.

The preferred combinations of (R<NUM> and R<NUM>) here are, in particular, (CnH2n+<NUM> and CmH<NUM>+<NUM>) and (CnH2n+<NUM> and O-CmH<NUM>+<NUM>), particularly preferably (CnH2n+<NUM> and O-CmH<NUM>+<NUM>).

The compounds of the formula VI are preferably selected from the group of the compounds of the formulae VI-<NUM> to VI-<NUM>:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which.

The compounds of the formula VI-<NUM> are preferably selected from the group of the compounds of the formulae VI-1a and VI-1b, more preferably selected from compounds of the formula VI-1a:
<CHM>
<CHM>
in which.

The preferred combinations of (R<NUM> and R<NUM>) here are, in particular, (CnH2n+<NUM> and CmH<NUM>+<NUM>) and (CnH2n+<NUM> and O-CmH<NUM>+<NUM>), in the case of formula VI-1a particularly preferably (CnH2n+<NUM> and CmH<NUM>+<NUM>) and in the case of formula VI-1b particularly preferably (CnH2n+<NUM> and O-CmH<NUM>+<NUM>).

The compounds of the formula VI-<NUM> are preferably selected from the compounds of the formula VI-3a to VI-3e:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which the parameters have the meaning given above under formula VI-<NUM> and preferably.

The compounds of the formula VI-<NUM> are preferably selected from compounds of the formulae VI-4a to VI-4e:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which the parameters have the meaning given above under formula VI-<NUM> and preferably.

The compounds of the formula VI-<NUM> are preferably selected from the compounds of the formulae VI-5a to VI-5d, preferably VI-5b:
<CHM>
<CHM>
<CHM>
<CHM>
in which the parameters have the meaning given above under formula VI-<NUM> and preferably.

The compounds of the formula VII are preferably selected from the group of the compounds of the formulae VII-<NUM> to VII-<NUM>:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

The compounds of the formula VII-<NUM> are preferably selected from the group of the compounds of the formulae VII-1a to VII-1d:
<CHM>
<CHM>
<CHM>
<CHM>
in which X<NUM> has the meaning given above for formula VII-<NUM> and.

The compounds of the formula VII-<NUM> are preferably selected from the group of the compounds of the formulae VII-2a and VII-2b, particularly preferably of the formula VII-2a:
<CHM>
<CHM>
in which.

The preferred combinations of (R<NUM> and R<NUM>) here are, in particular, (CnH2n+<NUM> and CmH<NUM>+<NUM>) and (CnH2n+<NUM> and O-CmH<NUM>+<NUM>), particularly preferably (CnH2n+<NUM> and CmH<NUM>+<NUM>).

The compounds of the formula VII-<NUM> are preferably compounds of the formula VII-3a:
<CHM>
in which.

The compounds of the formula VII-<NUM> are preferably compounds of the formula VII-4a:
<CHM>
in which.

The compounds of the formula VII-<NUM> are preferably selected from the group of the compounds of the formulae VII-5a and VII-5b, more preferably of the formula VII-5a:
<CHM>
<CHM>
in which.

The compounds of the formula VII-<NUM> are preferably selected from the group of the compounds of the formulae VII-6a and VII-6b:
<CHM>
<CHM>
in which.

The compounds of the formula VII-<NUM> are preferably selected from the group of the compounds of the formulae VII-7a to VII-7d:
<CHM>
<CHM>
<CHM>
<CHM>
in which.

The compounds of the formula VIII are preferably selected from the group of the compounds of the formulae VIII-<NUM> to VIII-<NUM>, more preferably these compounds of the formula VIII predominantly consist, even more preferably essentially consist and very particularly preferably completely consist thereof:
<CHM>
<CHM>
<CHM>
in which
one of.

The compounds of the formula VIII-<NUM> are preferably selected from the group of the compounds of the formulae VIII-1a to VIII-1c:
<CHM>
<CHM>
<CHM>
in which.

The compounds of the formula VIII-<NUM> are preferably compounds of the formula VIII-2a:
<CHM>
in which.

The preferred combinations of (R<NUM> and R<NUM>) here are, in particular, (CnH2n+<NUM> and CmH<NUM>+<NUM>), (CnH2n+<NUM> and O-CmH<NUM>+<NUM>) and (CH<NUM>=CH-(CH<NUM>)Z and CmH<NUM>+<NUM>), particularly preferably (CnH2n+<NUM> and CmH<NUM>+<NUM>).

The compounds of the formula VIII-<NUM> are preferably compounds of the formula VIII-3a:
<CHM>
in which.

The preferred combinations of (R<NUM> and R<NUM>) here are, in particular, (CnH2n+<NUM> and CmH<NUM>+<NUM>) and (CnH2n+<NUM> and O-CmH<NUM>+<NUM>).

The compounds of the formula IX are preferably selected from the group of the compounds of the formulae IX-<NUM> to IX-<NUM>:
<CHM>
<CHM>
<CHM>.

The compounds of the formula IX-<NUM> are preferably selected from the group of the compounds of the formulae IX-1a to IX-1e:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which the parameters have the meaning given above and preferably.

The compounds of the formula IX-<NUM> are preferably selected from the group of the compounds of the formulae IX-2a and IX-2b:
<CHM>
<CHM>
in which.

The compounds of the formula IX-<NUM> are preferably compounds of the formulae IX-3a and IX-3b:
<CHM>
<CHM>
in which.

In a preferred embodiment of the present invention the medium comprises one or more compounds of formula X
<CHM>
in which.

<CHM>
and
<CHM>
independently of one another, denote
<CHM>
<CHM>
<CHM>
<CHM>
preferably
<CHM>
or
<CHM>
and where
<CHM>
alternatively denotes
<CHM>
and n is <NUM> or <NUM>.

Preferably, the compounds of formula X are selected from the sub-formulae X-<NUM> and X-<NUM>
<CHM>
<CHM>
in which the occurring groups and parameters have the meanings given above for formula X.

Particularly preferably, the media according to the invention comprise one or more compounds selected from the group of compounds of the formulae X-<NUM>-<NUM> to X-<NUM>-<NUM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

In a preferred embodiment, the medium according to the invention comprises one or more compounds of formula XI
<CHM>
in which.

Preferably, the compounds of formula XI are selected from the group of compounds of the formulae XI-<NUM> to XI-<NUM>:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which the occurring groups have the meanings given above for formula XI and preferably.

Preferably, the medium according to the invention comprises one or more compounds of formula T
<CHM>
in which.

In a preferred embodiment, the liquid crystalline media according to the invention comprise one or more compounds selected from the group of compounds of the formulae T-1a to T-3b below:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which
<CHM>
have the meanings given above and n is <NUM>, <NUM>, <NUM>, <NUM>, <NUM><NUM> or <NUM>, preferably <NUM>, <NUM>, <NUM> or <NUM>, particularly preferably <NUM>.

In a particularly preferred embodiment of the present invention the media comprise one or more compounds selected from the compounds of the formulae T-1a and T-2a.

Preferred compounds of formula T-1a are selected from the group of compounds of the following sub-formulae:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which n is <NUM>, <NUM>, <NUM> or <NUM>, preferably <NUM>.

Preferred compounds of formula T-2a are selected from the group of compounds of the following sub-formulae:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which n is <NUM>, <NUM>, <NUM> or <NUM>, preferably <NUM>.

Very preferably, the medium according to the invention comprises one or more compounds of formula T-1a-<NUM>.

The media according to the present invention comprise one or more chiral dopants. Preferably these chiral dopants have an absolute value of the helical twisting power (HTP) in the range of from <NUM>-<NUM> to <NUM>-<NUM>, preferably in the range of from <NUM>-<NUM> to <NUM>-<NUM>. In case the media comprise two or more chiral dopants, these may have opposite signs of their HTP-values. This condition is preferred for some specific embodiments, as it allows to compensate the chirality of the respective compounds to some degree and, thus, may be used to compensate various temperature dependent properties of the resulting media in the devices. Generally, however, it is preferred that most, preferably all of the chiral compounds present in the media according to the present invention have the same sign of their HTP-values.

Preferably the chiral dopants present in the media according to the instant application are mesogenic compounds and most preferably they exhibit a mesophase on their own.

In a preferred embodiment of the present invention, the medium comprises two or more chiral compounds which all have the same algebraic sign of the HTP.

The temperature dependence of the HTP of the individual compounds may be high or low. The temperature dependence of the pitch of the medium can be compensated by mixing compounds having different temperature dependencies of the HTP in corresponding ratios.

For the optically active component, a multitude of chiral dopants, some of which are commercially available, is available to the person skilled in the art, such as, for example, cholesteryl nonanoate, R- and S-<NUM>, R- and S-<NUM>, R- and S-<NUM>, R- and S-<NUM>, R- and S-<NUM>, or CB15 (all Merck KGaA, Darmstadt).

Particularly suitable dopants are compounds which contain one or more chiral groups and one or more mesogenic groups, or one or more aromatic or alicyclic groups which form a mesogenic group with the chiral group.

Suitable chiral groups are, for example, chiral branched hydrocarbon radicals, chiral ethane diols, binaphthols or dioxolanes, furthermore mono- or polyvalent chiral groups selected from the group consisting of sugar derivatives, sugar alcohols, sugar acids, lactic acids, chiral substituted glycols, steroid derivatives, terpene derivatives, amino acids or sequences of a few, preferably <NUM>-<NUM>, amino acids.

Preferred chiral groups are sugar derivatives, such as glucose, mannose, galactose, fructose, arabinose and dextrose; sugar alcohols, such as, for example, sorbitol, mannitol, iditol, galactitol or anhydro derivatives thereof, in particular dianhydrohexitols, such as dianhydrosorbide (<NUM>,<NUM>:<NUM>,<NUM>-dianhydro-D-sorbide, isosorbide), dianhydromannitol (isosorbitol) or dianhydroiditol (isoiditol); sugar acids, such as, for example, gluconic acid, gulonic acid and ketogulonic acid; chiral substituted glycol radicals, such as, for example, mono- or oligoethylene or propylene glycols, in which one or more CH<NUM> groups are substituted by alkyl or alkoxy; amino acids, such as, for example, alanine, valine, phenylglycine or phenylalanine, or sequences of from <NUM> to <NUM> of these amino acids; steroid derivatives, such as, for example, cholesteryl or cholic acid radicals; terpene derivatives, such as, for example, menthyl, neomenthyl, campheyl, pineyl, terpineyl, isolongifolyl, fenchyl, carreyl, myrthenyl, nopyl, geraniyl, linaloyl, neryl, citronellyl or dihydrocitronellyl.

The media according to the present invention preferably comprise chiral dopants which are selected from the group of known chiral dopants. Suitable chiral groups and mesogenic chiral compounds are described, for example, in <CIT>, <CIT>, <CIT>, <CIT> and <CIT>, <CIT>, <CIT> and <CIT>. Examples are also compounds listed in Table F below.

Chiral compounds preferably used according to the present invention are selected from the group consisting of the formulae shown below.

Particular preference is given to chiral dopants selected from the group consisting of compounds of the following formulae A-I to A-III and A-Ch:
<CHM>
<CHM>
<CHM>
<CHM>
in which.

Particular preference is given to dopants selected from the group consisting of the compounds of the following formulae:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which.

Particularly preferred compounds of formula A are compounds of formula A-III.

Further preferred dopants are derivatives of the isosorbide, isomannitol or isoiditol of the following formula A-IV:
<CHM>
in which the group
<CHM>
is
<CHM>
<CHM>
or
<CHM>.

Examples of compounds of formula IV are:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which RIV is alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkylcarbonyloxy having up to <NUM> carbon atoms.

The compounds of the formula A-IV are described in <CIT>. The compounds of the formula A-V are described in <CIT>.

Very particularly preferred dopants are chiral binaphthyl derivatives, as described in <CIT>, chiral binaphthol acetal derivatives, as described in <CIT>, chiral TADDOL derivatives, as described in <CIT>, and chiral dopants having at least one fluorinated bridging group and a terminal or central chiral group, as described in <CIT> and <CIT>.

Particular preference is given to chiral compounds of the formula A-VI
<CHM>
in which.

Particular preference is given to chiral binaphthyl derivatives of the formula A-VI-<NUM>
<CHM>
in which ring B denotes <NUM>,<NUM>-phenylene or <NUM>,<NUM>-cyclohexylene which are optionally monosubstituted or polysubstituted by F, R<NUM> denotes alkyl having <NUM> to <NUM> C atoms,
Z<NUM> denotes -O-, -COO-, -OCO-, -OCH<NUM>-, -CH<NUM>O-, -CH<NUM>CH<NUM>- or -CH=CH-, and b is <NUM>, <NUM> or <NUM>,.

in particular those selected from the following formulae A-VI-1a to A-VI-1c:
<CHM>
<CHM>
<CHM>
in which R<NUM>, and Z<NUM> have the meanings defined above and preferably.

The concentration of the one or more chiral dopant(s), in the LC medium is preferably in the range from <NUM> % to <NUM> %, preferably from <NUM> % to <NUM> %, more preferably from <NUM> % to <NUM> %, and, most preferably from <NUM> % to <NUM> %. These preferred concentration ranges apply in particular to the chiral dopant S-<NUM> or R-<NUM> (both from Merck KGaA) and for chiral dopants having the same or a similar HTP. For Chiral dopants having either a higher or a lower absolute value of the HTP compared to S-<NUM> these preferred concentrations have to be decreased, respectively increased proportionally according to the ratio of their HTP values relatively to that of S-<NUM>.

The pitch p of the LC media or host mixtures according to the invention is preferably in the range of from <NUM> to <NUM>, more preferably from <NUM> to <NUM> and particularly preferably from <NUM> to <NUM>.

Preferably, the media according to the invention, comprise a stabilizer selected from the group of compounds of the formulae ST-<NUM> to ST-<NUM>. <CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
in which.

Of the compounds of the formula ST, special preference is given to the compounds of the formulae
<CHM>
<CHM>
in which n = <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>, preferably n = <NUM> or <NUM>
<CHM>
in which n = <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>, preferably n = <NUM>
<CHM>
in which n = <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>, preferably n = <NUM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

In the compounds of the formulae ST-3a and ST-3b, n preferably denotes <NUM>. In the compounds of the formula ST-2a, n preferably denotes <NUM>.

Very particularly preferred mixtures according to the invention comprise one or more stabilizers from the group of the compounds of the formulae ST-2a-<NUM>, ST-3a-<NUM>, ST-3b-<NUM>, ST-<NUM>-<NUM>, ST-<NUM>-<NUM> and ST-<NUM>:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

The compounds of the formulae ST-<NUM> to ST-<NUM> are preferably each present in the liquid-crystal mixtures according to the invention in amounts of <NUM> - <NUM>%, based on the mixture.

If the mixtures according to the invention comprise two or more compounds from the group of the compounds of the formulae ST-<NUM> to ST-<NUM>, the concentration correspondingly increases to <NUM> - <NUM>% in the case of two compounds, based on the mixtures.

However, the total proportion of the compounds of the formulae ST-<NUM> to ST-<NUM>, based on the mixture according to the invention, should not exceed <NUM>%.

Other mesogenic compounds which are not explicitly mentioned above can optionally and advantageously also be used in the media in accordance with the present invention. Such compounds are known to the person skilled in the art.

In a preferred embodiment of the present invention, the total concentration of compounds of formula N in the liquid-crystalline medium is <NUM> % or more, preferably <NUM> % or more, very preferably <NUM>% or more and particularly preferably <NUM> % or more.

In a preferred embodiment of the present invention, the liquid-crystalline media preferably comprise in total <NUM> % to <NUM> %, preferably <NUM> % to <NUM> % and particularly preferably <NUM> % to <NUM> % of compounds of formula N.

In a preferred embodiment of the present invention, the liquid-crystalline media comprise in total <NUM> % to <NUM> %, preferably <NUM> % to <NUM> % and particularly preferably <NUM> % to <NUM> % of one or more compounds of formula T, preferably selected from the formulae T-1a and T-2a, very preferably from T-1a-<NUM> and T-2a-<NUM>.

In a preferred embodiment of the present invention, the liquid-crystalline media comprise in total <NUM> % to <NUM> %, preferably <NUM> % to <NUM> % and particularly preferably <NUM> % to <NUM> % of one or more compounds of the formula T-1a.

In a preferred embodiment of the present invention, the liquid-crystalline media comprise in total <NUM> % to <NUM> %, preferably <NUM> % to <NUM> % and particularly preferably <NUM> % to <NUM> % of one or more compounds of the formula T-1a, and in addition <NUM> to <NUM>% of one or more compounds of the formula T-2a-<NUM>.

In a preferred embodiment, the medium comprises one or more compounds of formula I, preferably of formula I-<NUM> or I-<NUM>, in a total concentration in the range of from <NUM> % to <NUM> %, more preferably from <NUM> % to <NUM> %, and particularly preferably from <NUM> % to <NUM> %.

In a preferred embodiment of the present invention the medium comprises one or more compounds of formula II, preferably of formula II-<NUM>, in a total concentration of <NUM> % to <NUM> %, more preferably <NUM> % to <NUM> %, particularly preferably <NUM> % to <NUM> %.

In a preferred embodiment of the present invention the medium comprises one or more compounds of formula IIA-<NUM> in a total concentration of <NUM> % to <NUM> %, more preferably <NUM> % to <NUM> %, particularly preferably <NUM> % to <NUM> %.

In a preferred embodiment of the present invention the medium comprises one or more compounds of formula II-<NUM> in an total concentration of <NUM>% or less, more preferably <NUM>% or less, particularly preferably <NUM>% or less.

In a preferred embodiment of the present invention the medium comprises one or more compounds of formula III, preferably III-<NUM> and/or III-<NUM>, more preferably III-<NUM> and/or III-1b, in a total concentration of <NUM> % to <NUM> %, more preferably <NUM> % to <NUM> %, particularly preferably <NUM> % to <NUM> %.

In a preferred embodiment, the medium comprises one or more compounds of the formulae N and I and II and/or IIA, and III and T, preferably in a total concentration of <NUM>% or more, more preferably <NUM>%, <NUM>% or <NUM>% or more, very preferably <NUM>% or more and in particular <NUM>% or more.

In a preferred embodiment, the medium comprises one or more compounds of the formulae N and II and III and T, preferably in a total concentration of <NUM>% or more, more preferably <NUM>%, <NUM>% or <NUM>% or more, very preferably <NUM>% or more and in particular <NUM>% or more.

In a preferred embodiment, the medium comprises one or more compounds of the formulae N and I and III and T, preferably in a total concentration of <NUM>% or more, more preferably <NUM>%, <NUM>% or <NUM>% or more, very preferably <NUM>% or more and in particular <NUM>% or more.

Further preferred embodiments of the present invention, taken alone or in combination with one another, are as follows, wherein some compounds are abbreviated using the acronyms given in Table C below:.

The liquid-crystal media in accordance with the present invention preferably have a clearing point of <NUM> or more, more preferably <NUM> or more, more preferably <NUM> or more, more preferably <NUM> or more, more preferably <NUM> or more, particularly preferably <NUM> or more and very particularly preferably <NUM> or more.

The liquid-crystal media in accordance with the present invention preferably have a clearing point of <NUM> or less, more preferably <NUM> or less, particularly preferably <NUM> or less, and very particularly preferably <NUM> or less.

The nematic phase of the media according to the invention preferably extends at least from <NUM> or less to <NUM> or more. It is advantageous for the media according to the invention to exhibit even broader nematic phase ranges, preferably at least from -<NUM> or less to <NUM> or more, very preferably at least from -<NUM> or less to <NUM> or more and in particular at least from -<NUM> or less to <NUM> or more, very particularly preferably at least from -<NUM> or less to <NUM> or more.

The Δε of the liquid-crystal medium according to the present invention, at <NUM> and <NUM>, is preferably <NUM> or more, more preferably <NUM> or more and very preferably <NUM> or more.

The birefringence (Δn) of the liquid-crystal media according to the present invention, at <NUM> (NaD) and <NUM>, is preferably <NUM> or more, more preferably <NUM> or more, even more preferably <NUM> or more, very preferably <NUM> or more and in particular <NUM> or more.

The Δn of the liquid-crystal media according to the present invention, at <NUM> (NaD) and <NUM>, is preferably in the range from <NUM> to <NUM>, more preferably in the range from <NUM> to <NUM>, even more preferably in the range from <NUM> to <NUM> and very particularly preferably in the range from <NUM> to <NUM>.

In a preferred embodiment of the present application, the Δn of the liquid-crystal media in accordance with the present invention is preferably <NUM> or more, more preferably <NUM> or more.

The compounds of the formulae I to III in each case include dielectrically positive compounds having a dielectric anisotropy of greater than <NUM>, dielectrically neutral compounds having a dielectric anisotropy of less than <NUM> and greater than -<NUM> and dielectrically negative compounds having a dielectric anisotropy of -<NUM> or less.

The compounds of the formulae N, I, II and III are preferably dielectrically positive.

In the present application, the expression dielectrically positive describes compounds or components where Δε > <NUM>, dielectrically neutral describes those where -<NUM> ≤ Δε ≤ <NUM> and dielectrically negative describes those where Δε < -<NUM>. Δε is determined at a frequency of <NUM> and at <NUM>. The dielectric anisotropy of the respective compound is determined from the results of a solution of <NUM> % of the respective individual compound in a nematic host mixture. If the solubility of the respective compound in the host mixture is less than <NUM> %, the concentration is reduced to <NUM> %. The capacitances of the test mixtures are determined both in a cell having homeotropic alignment and in a cell having homogeneous alignment. The cell thickness of both types of cells is approximately <NUM>. The voltage applied is a rectangular wave having a frequency of <NUM> and an effective value of typically <NUM> V to <NUM> V, but it is always selected to be below the capacitive threshold of the respective test mixture.

Δε is defined as (ε∥ - ε⊥), while εave. is (ε∥ + <NUM>ε⊥) / <NUM>.

The host mixture used for the determination of physical constants of pure compounds by extrapolation is ZLI-<NUM> from Merck KGaA, Germany. The absolute values of the dielectric constants, the birefringence (Δn) and the rotational viscosity (γ<NUM>) of the compounds are determined from the change in the respective values of the host mixture on addition of the compounds. The concentration in the host is <NUM> % or in case of insufficient solubility <NUM> %. The values are extrapolated to a concentration of <NUM> % of the added compounds.

In the examples, the phase sequences of pure compounds are given using the following abbreviations:
K: crystalline, N: nematic, SmA: smectic A, SmB: smectic B, I: isotropic.

Components having a nematic phase at the measurement temperature of <NUM> are measured as such, all others are treated like compounds.

The expression threshold voltage in the present application refers to the optical threshold and is quoted for <NUM> % relative contrast (V<NUM>), and the expression saturation voltage refers to the optical saturation and is quoted for <NUM> % relative contrast (V<NUM>), in both cases unless expressly stated otherwise. The capacitive threshold voltage (V<NUM>), also called the Freedericks threshold (VFr), is only used if expressly mentioned.

The parameter ranges indicated in this application all include the limit values, unless expressly stated otherwise.

The different upper and lower limit values indicated for various ranges of properties in combination with one another give rise to additional preferred ranges.

Throughout this application, the following conditions and definitions apply, unless expressly stated otherwise. All concentrations are quoted in per cent by weight and relate to the respective mixture as a whole, all temperatures are quoted in degrees Celsius and all temperature differences are quoted in differential degrees. All physical properties are determined in accordance with "<NPL>, and are quoted for a temperature of <NUM>, unless expressly stated otherwise. The optical anisotropy (Δn) is determined at a wavelength of <NUM>. The dielectric anisotropy (Δε) is determined at a frequency of <NUM>. The threshold voltages, as well as all other electro-optical properties, are determined using test cells produced at Merck KGaA, Germany. The test cells for the determination of Δε have a cell thickness of approximately <NUM>. The electrode is a circular ITO electrode having an area of <NUM><NUM> and a guard ring. The orientation layers are SE-<NUM> from Nissan Chemicals, Japan, for homeotropic orientation (ε∥) and polyimide AL-<NUM> from Japan Synthetic Rubber, Japan, for homogeneous orientation (ε⊥). The capacitances are determined using a Solatron <NUM> frequency response analyser using a sine wave with a voltage of <NUM> Vrms. The light used in the electro-optical measurements is white light. A set-up using a commercially available DMS instrument from Autronic-Melchers, Germany, is used here. The characteristic voltages have been determined under perpendicular observation. The threshold (V<NUM>), mid-grey (V<NUM>) and saturation (V<NUM>) voltages have been determined for <NUM> %, <NUM> % and <NUM> % relative contrast, respectively.

The liquid-crystalline media are investigated with respect to their properties in the microwave frequency range as described in <NPL>. Compare in this respect also A. <NPL>, and <CIT>, in which a measurement method is likewise described in detail.

The liquid crystal is introduced into a polytetrafluoroethylene (PTFE) or quartz capillary. The capillary has an inner diameter of <NUM> and an outer diameter of <NUM>. The effective length is <NUM>. The filled capillary is introduced into the center of the cylindrical cavity with a resonance frequency of <NUM>. This cavity has a length of <NUM> and a radius of <NUM>. The input signal (source) is then applied, and the frequency depending response of the cavity is recorded using a commercial vector network analyzer (N5227A PNA Microwave Network Analyzer, Keysight Technologies Inc. For other frequencies, the dimensions of the cavity are adapted correspondingly.

The change in the resonance frequency and the Q factor between the measurement with the capillary filled with the liquid crystal and the measurement without the capillary filled with the liquid crystal is used to determine the dielectric constant and the loss angle at the corresponding target frequency by means of equations <NUM> and <NUM> in the above-mentioned publication <NPL>, as described therein.

The values for the components of the properties perpendicular and parallel to the director of the liquid crystal are obtained by alignment of the liquid crystal in a magnetic field. To this end, the magnetic field of a permanent magnet is used. The strength of the magnetic field is <NUM> tesla.

Preferred components are phase shifters, varactors, wireless and radio wave antenna arrays, matching circuit adaptive filters and others.

In the present application, the term compounds is taken to mean both one compound and a plurality of compounds, unless expressly stated otherwise.

All mixtures according to the invention are nematic. The liquid-crystal media according to the invention preferably have nematic phases in preferred ranges given above. The expression have a nematic phase here means on the one hand that no smectic phase and no crystallization are observed at low temperatures at the corresponding temperature and on the other hand that no clearing occurs on heating from the nematic phase. At high temperatures, the clearing point is measured in capillaries by conventional methods. The investigation at low temperatures is carried out in a flow viscometer at the corresponding temperature and checked by storage of bulk samples: The storage stability in the bulk (LTS) of the media according to the invention at a given temperature T is determined by visual inspection. <NUM> of the media of interest are filled into a closed glass vessel (bottle) of appropriate size placed in a refrigerator at a predetermined temperature. The bottles are checked at defined time intervals for the occurrence of smectic phases or crystallization. For every material and at each temperature two bottles are stored. If crystallization or the appearance of a smectic phase is observed in at least one of the two correspondent bottles the test is terminated and the time of the last inspection before the one at which the occurrence of a higher ordered phase is observed is recorded as the respective storage stability. The test is finally terminated after <NUM>, i. e an LTS value of <NUM> means that the mixture is stable at the given temperature for at least <NUM>.

The liquid crystals employed preferably have a positive dielectric anisotropy. This is preferably <NUM> or more, preferably <NUM> or more, particularly preferably <NUM> or more and very particularly preferably <NUM> or more.

Furthermore, the liquid-crystal media according to the invention are characterized by high anisotropy values in the microwave range. The birefringence at about <NUM> is, for example, preferably <NUM> or more, particularly preferably <NUM> or more, particularly preferably <NUM> or more, particularly preferably <NUM> or more and very particularly preferably <NUM> or more. In addition, the birefringence is preferably <NUM> or less.

The dielectric anisotropy in the microwave range is defined as <MAT>.

The material quality (η) is defined as <MAT> , where
the maximum dielectric loss is <MAT>.

The tunability τ of the medium according to the invention, measured at <NUM> and <NUM> is <NUM> or more, preferably <NUM> or more, <NUM> or more, <NUM> or more, <NUM> or more, or <NUM> or more, very preferably <NUM> or more and in particular <NUM> or more.

The material quality (η) of the preferred liquid-crystal materials is <NUM> or more, preferably <NUM> or more, preferably <NUM> or more, preferably <NUM> or more, preferably <NUM> or more, preferably <NUM> or more, particularly preferably <NUM> or more and very particularly preferably <NUM> or more.

In the corresponding components, the preferred liquid-crystal materials have phase shifter qualities of <NUM>°/dB or more, preferably <NUM>°/dB or more, preferably <NUM>°/dB or more, preferably <NUM>°/dB or more, preferably <NUM>°/dB or more, particularly preferably <NUM>°/dB or more and very particularly preferably <NUM>°/dB or more.

In some embodiments, however, liquid crystals having a negative value of the dielectric anisotropy can also advantageously be used.

The liquid crystals employed are either individual substances or mixtures. They preferably have a nematic phase.

The liquid-crystal media in accordance with the present invention may comprise further additives and chiral dopants in the usual concentrations. The total concentration of these further constituents is in the range from <NUM> % to <NUM> %, preferably <NUM> % to <NUM> %, based on the mixture as a whole. The concentrations of the individual compounds used are each preferably in the range from <NUM> % to <NUM> %. The concentration of these and similar additives is not taken into consideration when quoting the values and concentration ranges of the liquid-crystal components and liquid-crystal compounds of the liquid-crystal media in this application.

Preferably the media according to the present invention comprise one or more chiral compounds as chiral dopants in order to adjust their cholesteric pitch. Their total concentration in the media according to the instant invention is preferably in the range <NUM> % to <NUM> %, more preferably from <NUM> % to <NUM> % and most preferably from <NUM> % to <NUM>%.

Optionally the media according to the present invention may comprise further liquid crystal compounds in order to adjust the physical properties. Such compounds are known to the skilled person. Their concentration in the media according to the instant invention is preferably <NUM> % to <NUM> %, more preferably <NUM> % to <NUM> % and most preferably <NUM> % to <NUM> %.

The response times are given as rise time (τon) for the time for the change of the relative tuning, respectively of the relative contrast for the electro-optical response, from <NUM> % to <NUM> % (t<NUM> - t<NUM>), i.e. including the delay time (t<NUM> - t<NUM>), as decay time (τoff) for the time for the change of the relative tuning, respectively of the relative contrast for the electro-optical response, from <NUM> % back to <NUM> % (t<NUM> - t<NUM>) and as the total response time (τtotal = τon + τoff), respectively.

The liquid-crystal media according to the invention consist of a plurality of compounds, preferably <NUM> to <NUM>, more preferably <NUM> to <NUM> and very preferably <NUM> to <NUM> compounds. These compounds are mixed in a conventional manner. In general, the desired amount of the compound used in the smaller amount is dissolved in the compound used in the larger amount. If the temperature is above the clearing point of the compound used in the higher concentration, it is particularly easy to observe completion of the dissolution process. It is, however, also possible to prepare the media in other conventional ways, for example using so-called pre-mixes, which can be, for example, homologous or eutectic mixtures of compounds, or using so-called "multi-bottle" systems, the constituents of which are themselves ready-to-use mixtures.

All temperatures, such as, for example, the melting point T(C,N) or T(C,S), the transition from the smectic (S) to the nematic (N) phase T(S,N) and the clearing point T(N,I) of the liquid crystals, are quoted in degrees Celsius. All temperature differences are quoted in differential degrees.

In the present invention and especially in the following examples, the structures of the mesogenic compounds are indicated by means of abbreviations, also referred to as acronyms. In these acronyms, the chemical formulae are abbreviated as follows using Tables A to D below. All groups CnH2n+<NUM>, CmH<NUM>+<NUM> and ClH<NUM>+<NUM>, and CnH2n, CmH<NUM> and ClH<NUM> denote straight-chain alkyl or alkylene, respectively, in each case having n, m or I C atoms, wherein n and m, independently are <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM> and I is <NUM>, <NUM> or <NUM>. Table A lists the codes used for the ring elements of the core structures of the compounds, while Table B shows the linking groups. Table C gives the meanings of the codes for the left-hand or right-hand end groups. Table D shows illustrative structures of compounds with their respective abbreviations.

in which n and m each denote integers, and the three dots ". " are placeholders for other abbreviations from this table.

The following table shows illustrative structures together with their respective abbreviations. These are shown in order to illustrate the meaning of the rules for the abbreviations. They furthermore represent compounds which are preferably used.

in which m and n, identically or differnetly, are <NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM> or <NUM>.

Preferably, the medium according to the invention comrises one or more compounds selected from the compounds of Table C.

The following table, Table D, shows illustrative compounds which can be used as alternative stabilizers in the mesogenic media in accordance with the present invention. The total concentration of these and similar compounds in the media is preferably <NUM> % or less.

In a preferred embodiment of the present invention, the mesogenic media comprise one or more compounds selected from the group of the compounds from Table D.

The following table, Table E, shows illustrative compounds which can preferably be used as chiral dopants in the mesogenic media in accordance with the present invention.

In a preferred embodiment of the present invention, the mesogenic media comprise one or more compounds selected from the group of the compounds of Table E.

The mesogenic media in accordance with the present application preferably comprise two or more, preferably four or more, compounds selected from the group consisting of the compounds from the above tables.

The following examples illustrate the present invention without limiting it in any way. It is clear to the person skilled in the art from the physical properties what properties can be achieved and in what ranges they can be modified. In particular, the combination of the various properties which can preferably be achieved is thus well defined for the person skilled in the art.

A mixture of [<NUM>-(<NUM>-butylcyclohexyl)phenyl]boronic acid (<NPL> ) (<NUM>, <NUM> mmol), <NUM>-bromopyrimidin-<NUM>-amine (<NPL>) (<NUM>, <NUM> mmol), potassium carbonate (<NUM>, <NUM> mmol) in ethanol (<NUM>), dist. water (<NUM>) and toluene (<NUM>) is treated with bis(triphenylphosphine)palladium(ll)dichloride (<NUM>), heated to reflux and stirred under argon atmosphere at reflux temperature overnight. It is cooled down to RT and concentrated in vacuo. The residue is purified by silica gel chromatography (dichloromethane and ethyl acetate) to give <NUM>-[<NUM>-(<NUM>-butylcyclohexyl)phenyl]pyrimidin-<NUM>-amine as a colorless solid.

A solution of <NUM>-[<NUM>-(<NUM>-butylcyclohexyl)phenyl]pyrimidin-<NUM>-amine (<NUM>, <NUM> mmol) and DABCO (<NUM>, <NUM> mmol) in dichloromethane (<NUM>) is cooled to <NUM>, and thiophosgene (<NUM>, <NUM> mmol) is added dropwise by syringe. The suspension is stirred at RT for <NUM>. Then the reaction mixture is hydrolyzed with dist. water and brine. The mixture is stirred for <NUM>, then the aqueous phase is separated and extracted with dichloromethane. The combined organic phases are washed with brine, dried (sodium sulfate) and concentrated in vacuo. The residue is purified by silica gel chromatography (n-heptane and toluene) and crystallization (n-heptane) to give <NUM>-[<NUM>-(<NUM>-butylcyclohexyl)phenyl]-<NUM>-isothiocyanato-pyrimidine as a colorless solid.

Phase sequence: K <NUM> I. <MAT> <MAT> <MAT>.

A mixture of [<NUM>-(<NUM>-butylcyclohexyl)phenyl]boronic acid (<NPL> ) (<NUM>, <NUM> mmol), <NUM>-bromo-<NUM>-chloro-<NUM> pyridinamine (<NPL>) (<NUM>, <NUM> mmol), potassium carbonate (<NUM>, <NUM> mmol) in dioxane (<NUM>), dist. water (<NUM>) is treated with bis(triphenylphosphine)- palladium(II)dichloride (<NUM>), heated up to reflux and stirred under argon atmosphere at reflux temperature overnight. It is then cooled down to RT and concentrated in vacuo. The residue is purified by silica gel chromatography (dichloromethane and ethyl acetate) to give <NUM>-[<NUM>-(<NUM>-butylcyclohexyl)phenyl]-<NUM>-chloro-pyridin-<NUM>-amine as a colorless solid.

A solution of <NUM>-[<NUM>-(<NUM>-butylcyclohexyl)phenyl]-<NUM>-chloro-pyridin-<NUM>-amine (<NUM>) (<NUM>, <NUM> mmol) and DABCO (<NUM>, <NUM> mmol) in dichloromethane (<NUM>) is cooled to <NUM>, and thiophosgene (<NUM>, <NUM> mmol) is added dropwise by syringe. The suspension is stirred at RT for <NUM>. Then the reaction mixture is hydrolyzed with dist. water and brine. The mixture is stirred for <NUM>, then aqueous phase is separated and extracted with dichloromethane. The combined organic phases are washed with brine, dried (sodium sulfate) and concentrated in vacuo. The residue is purified by silica gel chromatography (n-heptane and toluene) and crystallization (n-heptane). <NUM>-[<NUM>-(<NUM>-butylcyclohexyl)phenyl]-<NUM>-chloro-<NUM>-isothiocyanato-pyridine (<NUM>) is isolated as a colorless solid.

Phase sequence: K <NUM> N <NUM> I I. <MAT> <MAT>.

A mixture of [<NUM>-(<NUM>-butylcyclohexyl)phenyl]boronic acid (<NPL>) (<NUM>, <NUM> mmol), <NUM>-bromopyridin-<NUM>-amine (<NPL>) (<NUM>, <NUM> mmol), potassium carbonate (<NUM>, <NUM> mmol) in dioxane (<NUM>) and dist. water (<NUM>) is treated with bis(triphenylphosphine)-palladium(II)dichloride (<NUM>), heated to reflux and stirred under argon atmosphere at reflux temperature overnight. It is cooled down to RT and concentrated in vacuo. The residue is purified by silica gel chromatography (dichloromethane and ethyl acetate) to give <NUM>-[<NUM>-(<NUM>-butylcyclohexyl)phenyl]pyridin-<NUM>-amine as a colorless solid.

A solution of <NUM>-[<NUM>-(<NUM>-butylcyclohexyl)phenyl]pyridin-<NUM>-amine (<NUM>, <NUM> mmol) and DABCO (<NUM>, <NUM> mmol) in dichloromethane (<NUM>) is cooled to <NUM>, and thiophosgene (<NUM>, <NUM> mmol) is added dropwise by syringe. The suspension is stirred at RT for <NUM> and hydrolyzed with dist. water and brine. The aqueous phase is separated and extracted with dichloromethane. The combined organic phases are washed with brine, dried (sodium sulfate) and concentrated in vacuo. The residue is purified by silica gel chromatography (n-heptane and toluene) and crystallization (n-heptane) to give <NUM>-[<NUM>-(<NUM>-butylcyclohexyl)phenyl]-<NUM>-isothiocyanato-pyridine as a colorless solid.

Phase sequence: K <NUM> SmA <NUM> N <NUM> I <MAT> <MAT> <MAT>.

A mixture of [<NUM>-(<NUM>-butylcyclohexyl)phenyl]boronic acid (<NPL> ) (<NUM>, <NUM> mmol), <NUM>-bromo-<NUM>-chloro-<NUM> pyridinamine (<NPL>) (<NUM>, <NUM> mmol), potassium carbonate (<NUM>, <NUM> mmol) in dioxane (<NUM>), dist. water (<NUM>) is treated with bis(triphenylphosphine)- palladium(II)dichloride (<NUM>), heated up to reflux and stirred under argon atmosphere at reflux temperature overnight. It is then cooled down to RT and concentrated in vacuo. The residue is purified by silica gel chromatography (dichloromethane and ethyl acetate) to give <NUM><NUM>-[<NUM>-(<NUM>-butylcyclohexyl)phenyl]-<NUM>-chloro-pyridin-<NUM>-amine as a colorless solid.

A solution of <NUM>-[<NUM>-(<NUM>-butylcyclohexyl)phenyl]-<NUM>-chloro-pyridin-<NUM>-amine (<NUM>, <NUM> mmol) and DABCO (<NUM>, <NUM> mmol) in dichloromethane (<NUM>) is cooled to <NUM>, and thiophosgene (<NUM>, <NUM> mmol) is added dropwise by syringe. The suspension is stirred at RT for <NUM>. Then the reaction mixture is hydrolyzed with dist. water and brine. The mixture is stirred for <NUM>, then aqueous phase is separated and extracted with dichloromethane. The combined organic phases are washed with brine, dried (sodium sulfate) and concentrated in vacuo. The residue is purified by silica gel chromatography (n-heptane and toluene) and crystallization (n-heptane) to give <NUM>-[<NUM>-(<NUM>-butylcyclohexyl)phenyl]-<NUM>-chloro-<NUM>-isothiocyanato-pyridine as a colorless solid.

Phase sequence: K <NUM> SmA (<NUM>) N <NUM> I.

In analogy to Synthesis Examples1 to <NUM> the following compounds are obtained:.

Liquid-crystal mixtures H1 to H3 and M1 to M9 having the compositions and properties as indicated in the following tables are prepared and characterized with respect to their general physical properties and their applicability in microwave components at <NUM> and <NUM>.

Addition of the compound CPMI-<NUM>-S according to the invention to the medium H1 results in an improvement of the figure of merit η from <NUM> to <NUM> due to a higher tunability τ and a lower dielectric loss tan δε r,⊥.

Compared to the host mixture H2, the medium M2 has a significantly improved clearing temperature due to the presence of the compound CPNI-<NUM>-S according to the invention.

Addition of the compound CPNI(5CI)-<NUM>-S according to the invention to the medium H2 results in an improvement of the figure of merit η from <NUM> to <NUM> due to a lower dielectric loss tan δ.

The compound CPNI(2CI)-<NUM>-S is highly suitable for the use in a medium according to the invention due to its favourable application properties.

The medium M5 has a significantly lower dielectric loss than the host medium H3 alone, where the figure-of-merit is almost unchanged.

Medium M6 shows that the effect shown in medium M5 is further improved when the concentration of the compound of formula CPMI-<NUM>-S according to the invention is increased from <NUM>% to <NUM>%.

Due to the presence of the compound CPNI(5CI)-<NUM>-S according to the invention, mixture example M7 has a very high figure-of-merit h due to a high tunability and in particular a very low dielectric loss.

Due to the presence of the compound CPNI(5CI)-<NUM>-S according to the invention, mixture example M8 has a very high figure-of-merit η due to a high tunability and in particular a very low dielectric loss.

Claim 1:
A compound selected from the compounds of the formulae N-<NUM> to N-<NUM>
<CHM>
<CHM>
<CHM>
in which
RN denotes H, alkyl or alkoxy each having <NUM> to <NUM> C atoms, or alkenyl, alkenyloxy or alkoxyalkyl each having <NUM> to <NUM> C atoms, in which one or more CH<NUM>-groups may be replaced by
<CHM>
or denotes a group RP,
RP denotes halogen, CN, NCS, RF, RF-O- or RF-S-, wherein
RF denotes fluorinated alkyl having <NUM> to <NUM> C atoms or fluorinated alkenyl having <NUM> to <NUM> C atoms,
ZN1 and ZN2, identically or differently, denote -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -C≡C-C≡C- or a single bond,
<CHM>
denote a radical selected from the following groups:
a) the group consisting of <NUM>,<NUM>-phenylene, <NUM>,<NUM>-naphthylene and <NUM>,<NUM>-naphthylene, in which one or two CH groups may be replaced by N and in which one or more H atoms may be replaced by L,
b) the group consisting of trans-<NUM>,<NUM>-cyclohexylene, <NUM>,<NUM>-cyclohexenylene, bicyclo-[<NUM>.<NUM>]pentane-<NUM>,<NUM>-diyl, <NUM>,<NUM>'-bicyclohexylene, bicyclo[<NUM>.<NUM>]octane-<NUM>,<NUM>-diyl and spiro[<NUM>]heptane-<NUM>,<NUM>-diyl, in which one or more non-adjacent CH<NUM> groups may be replaced by -O- and/or -S- and in which one or more H atoms may be replaced by F,
c) the group consisting of thiophene-<NUM>,<NUM>-diyl, thieno[<NUM>,<NUM>-b]thiophene-<NUM>,<NUM>-diyl and selenophene-<NUM>,<NUM>-diyl, each of which may also be mono- or polysubstituted by L, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF<NUM> or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having <NUM> to <NUM> C atoms,
Y<NUM> and Y<NUM>, identically or differently, denote H, F, Cl or CH<NUM>, and
t is <NUM> or <NUM>.