Indene derivatives

Abstract

The present invention relates to an indene derivative of formula D as specified in claim 1, to a liquid crystal medium comprising a compound of formula D and to high- frequency components comprising these media, especially microwave components for high-frequency devices, such as devices for shifting the phase of microwaves, tunable filters, tunable metamaterial structures, and electronic beam steering antennas, e.g. phased array antennas.

Description

[0001] Indene Derivatives The present invention relates to indene derivatives, to liquid-crystalline media comprising same, and to high-frequency components comprising these media, especially microwave components for high-frequency devices, such as devices for shifting the phase of microwaves, tunable filters, tunable metamaterial structures, and electronic beam steering antennas (e.g., phased array antennas), and to devices comprising said components. The invention further relates to an optical component comprising said liquid-crystalline media, operable in the infrared region (IR) of the electromagnetic spectrum. The invention further relates to the use of said LC medium in the infrared region and to devices comprising said optical component. Liquid-crystalline media have 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 DE 102004029429 A and in JP 2005- 120208 (A). A. Gaebler, F. Goelden, S. Müller, A. Penirschke and R. Jakoby “Direct Simulation of Material Permittivities using an Eigen-Susceptibility Formulation of the Vector Variational Approach”, 12MTC 2009 – International Instrumentation and Measurement Technology Conference, Singapore, 2009 (IEEE), pp.463-467, describe the corresponding properties of the known liquid-crystal mixture E7 (Merck KGaA, Germany). DE 102004029429 A 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. 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 P24-041 AT 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 of formula D defined below is provided and a liquid crystalline medium comprising the compound. The present invention relates to a compound of formula D D in which RDdenotes H, straight-chain alkyl having 1 to 12 C atoms or branched alkyl having 3 to 12 C atom, or straight-chain alkenyl having 2 to 12 C atoms, or branched alkenyl having 3 to 12 C atoms, or straight-chain alkynyl having 2 to 12 C atoms or branched alkynyl having 4 to 12 C atoms, in which one or more CH2-groups adjacent CH2-groups may be replaced by O, or denotes a group RP, RPdenotes halogen, -CN, -NCS, RF-, RF-O- or RF-S-, wherein RFdenotes fluorinated alkyl having 1 to 9 C atoms, ZD1, ZD2, ZD3and ZD4, identically or differently, denote -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -N=N-, -C=N-N=C-, -CH=N-, -N=CH-, -C^C-, -C^C-C^C-, or a single bond, where ZD1alternatively denotes -O-, -S-, -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)3-, -(CH2)4-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH=CH-CH2O-, -CH=CH-CO-O-, -OCH2-CH=CH-, or -O-CO-CH=CH-, XDdenotes -C^C-CN, -NCS, or -C^C-NCS, preferably -NCS, P24-041 AT a radical selected from the following groups: a) the group consisting of 1,4-phenylene, 1,4-naphthylene, and 2,6-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-1,4-cyclohexylene, 1,4-cyclohexenylene, tetralin- 2,6-diyl, tetralin-5,8-diyl, decalin-2,6-diyl, bicyclo[1.1.1]pentane-1,3-diyl, 4,4´- bicyclohexylene, bicyclo[2.2.2]octane-1,4-diyl, and spiro[3.3]heptane-2,6-diyl, in which one or two CH groups may be replaced by N, one or more non-adjacent CH2groups may be replaced by -O- and / or -S- and in which one or more H atoms may be replaced by L, c) the group consisting of thiophene-2,5-diyl, thieno[3,2-b]thiophene-2,5-diyl, and selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF5or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy each having 1 to 12 C atoms, or cycloalkyl having 3 to 5 C atoms, t1, t2, t3 and t4, identically or differently, are 0,1 or 2, where t1 + t2 + t3 + t4 is 1, 2 or 3. According to another aspect of the present invention there is provided a liquid crystal medium comprising one or more compounds of formula D. Preferred embodiments of the present invention are subject-matter of the dependent claims or can also be taken from the description. P24-041 AT 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 in the microwave range of the electromagnetic spectrum by using compounds of formula D in liquid-crystalline media. In particular, the media according to the invention comprising the compound according to the invention are distinguished by an improved figure-of-merit ^^due to a higher tunability ^^and lower dielectric loss. The media according to the present invention are further 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. 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). According to another aspect of the present invention there is thus 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. P24-041 AT The medium according to the invention is likewise suitable for use in the infrared region of the electromagnetic spectrum. The invention thus further relates to the use of the medium defined above in the infrared region of the electromagnetic spectrum, preferably in the A-band, and / or B- band and / or C-band, for phase modulation of said infrared light. According to another aspect of the present invention there is provided an optical component comprising the liquid crystal medium according to the invention sandwiched between a pair of substrates. The invention further relates to a device comprising the optical component according to the invention. Preferred devices are infrared imagers, wavelength selective switches, LCoS-SLM, LIDAR systems, wavelength-division multiplexing (WDM) systems, reconfigurable optical add-drop multiplexer (ROADM), and nonmechanical beam steering, e.g. steerable Electro Evanescent Optical Refraction (SEEOR) prism as published in the article P. McManamon, 2006, "Agile Nonmechanical Beam Steering," Opt. Photon. News 17(3): 24-29. According to another aspect of the present invention there is provided a method of spatially modulating infrared light, the method comprising, i) providing an optical component comprising first and second substrates facing each other and each having a surface, the first substrate comprising at least one first electrode, the second substrate comprising at least one second electrode, the component further comprising a liquid crystal layer sandwiched between the first and second substrates wherein the liquid crystal comprises one or more compounds selected from the compounds of formula D indicated above; ii) receiving incident infrared light at a surface of said optical component; iii) applying a predetermined voltage to each of the individual electrodes formed on the first and second substrate in order to modulate a refractive index of the liquid crystal layer. According to another aspect of the present invention there is provided a method of manufacturing an optical phase modulator, comprising at least the steps of P24-041 AT a) providing a first substrate with a first electrode, optionally having a two dimensional array of individually electrically drivable cells; b) depositing a liquid crystal medium as set forth in claim 1 over the first substrate; and c) mounting a second substrate with a second electrode onto the liquid crystal material. The optical component according to the invention is distinguished by excellent operational stability when exposed to the environment because of high clearing temperature, broad nematic phase range and excellent low-temperature stability (LTS) of the liquid crystal medium used therein. As a result, the component and devices containing the component are operable under extreme temperature conditions. The media used in the component according to the invention are 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 components and devices according to the invention. Herein, “high-frequency technology” means applications of electromagnetic radiation having frequencies in the range of from 1 MHz to 1 THz, preferably from 1 GHz to 500 GHz, more preferably 2 GHz to 300 GHz, particularly preferably from about 5 GHz to 150 GHz. As used herein, infrared region of the electromagnetic spectrum is taken to mean the spectral region of electromagnetic radiation having a wavelength in the range of from 0.75 µm to 1000 µm. As used herein, infrared A (IR-A) is taken to mean the spectral region of electromagnetic radiation having a wavelength in the range of from 0.75 µm to 1.4 µm. As used herein, infrared B (IR-B) is taken to mean the spectral region of electromagnetic radiation having a wavelength in the range of from 1.4 µm to 3 µm. P24-041 AT As used herein, infrared C (IR-C) is taken to mean the spectral region of electromagnetic radiation having a wavelength in the range of from 3 µm to 1000 µm. Preferably, the optical component according to the invention operates at a wavelength in the range of from 750 nm to 2500 nm, in particular from 1530 nm to 1565 nm. A very preferred light source for applications according to the invention is an IR laser emitting light with a wavelength of 1,55 µm or an IR laser emitting light with a wavelength of 905 nm. As used herein, halogen is F, Cl, Br or I, preferably F or Cl, particularly preferably F. Herein, alkyl is straight-chain or branched or cyclic and has 1 to 15 C atoms, is preferably straight-chain and has, unless indicated otherwise, 1, 2, 3, 4, 5, 6 or 7 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, 2- methylbutyl, 2-methylhexyl or 2-ethylhexyl. As used herein, cyclic alkyl is taken to mean straight-chain or branched alkyl or alkenyl having up to 12 C atoms, preferably alkyl having 1 to 7 C atoms, in which a group CH2is replaced with a carbocyclic ring having 3 to 5 C atoms, very preferably selected from the group consisting of cyclopropylalkyl, cyclobutylalkyl, cyclopentylalkyl and cyclopentenylalkyl. Herein, an alkoxy radical is straight-chain or branched and contains 1 to 15 C atoms. It is preferably straight-chain and has, unless indicated otherwise, 1, 2, 3, 4, 5, 6 or 7 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 2 to 15 C atoms, which is straight-chain or branched and contains at least one C-C double bond. It is preferably straight-chain and has 2 to 7 C atoms. Accordingly, it is preferably vinyl, P24-041 AT prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-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-2-enyl, but-2- and -3-enyl, and pent-3- and -4-enyl are particularly preferred. Herein, alkynyl is taken to mean an alkynyl radical having 2 to 15 C atoms, which is straight-chain or branched and contains at least one C-C triple bond.1- and 2-propynyl and 1-, 2- and 3-butynyl are preferred. In case RFdenotes a halogenated alkyl-, alkoxy-, alkenyl or alkenyloxy it can be branched or unbranched. Preferably it is unbranched, mono- poly or perfluorinated, preferably perfluorinated and has 1, 2, 3, 4, 5, 6 or 7 C atoms, in case of alkenyl 2, 3, 4, 5, 6 or 7 C atoms. RPpreferably denotes CN, NCS, Cl, F, -(CH2)n-CH=CF2, -(CH2)n-CH=CHF, -(CH2)n- CH=Cl2, -CnF2n+1, -(CF2)n-CF2H, -(CH2)n-CF3, -(CH2)n-CHF2, -(CH2)nCH2F, -CH=CF2, - O(CH2)n-CH=CF2, -O(CH2)nCHCl2, -OCnF2n+1, -O(CF2)n-CF2H, -O(CH2)nCF3, -O(CH2)n- CHF2, -O(CF)nCH2F, -OCF=CF2, -SCnF2n+1, -S(CF)n-CF3, wherein n is an integer from 0 to 7. The compounds of the general formula D 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), and 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 D. Preferred synthetic pathways towards compounds according to the invention are exemplified in the reaction schemes below in which the occurring groups and parameters have the meanings given for formula D. It is further illustrated by means of P24-041 AT the working examples and can be adapted to the particular desired compounds of the general formula D by choice of suitable starting materials. Preferred starting materials are suitably substituted indanones (1) Suitable groups X1are leaving groups selected from but not limited to Cl, Br, I, methane sulfonate (MsO), methylphenyl sulfonate (TsO), trifluoromethane sulfonate (TfO), perfluorononyl sulfonate (NsO), etc. The indanones (1) are alkylated in the ^-position using a strong, non-nucleophilic base such as lithiumdiisopropylamide followed by treatment with an alkyl halide. The resulting ketone (2) is reduced to the alcohol (3) followed by elimination of water to give the indene intermediate (4) (Scheme 1). Scheme 1 The indenones (5) are accessible by the method described in the article S. H. Han et al. Synthesis of Indenes that are Derived from Aldimines with Enones Under Rhodium(III) Catalysis, in: Asian J. Org. Chem.2017, 6, 1823 – 1829, which can be transferred to the intermediates (4) by reduction using known methods . Ring elements are introduced for example in analogy to the process described in US 2012 / 0132854 A1 for the synthesis of compound (6) that can be further P24-041 AT functionalised as exemplified in scheme 2 via the bromine atom. From indanone (6) indene (7) is made according to scheme 1. An access to indanones is also described in the article Matthias Bremer and Lars Lietzau, 1,1,6,7-Tetrafluoroindanes: improved liquid crystals for LCD-TV application, in: New J. Chem., 2005, 29 , 72–74. The indenes (8) obtained by the processes discussed above are further reacted in standard cross coupling reactions such as Sonogashira or Suzuki reactions to give for example the intermediates 10 and 12 exemplified by scheme 2. Isomers are synthesised in an analogous fashion. Scheme 2 P24-041 AT In scheme 2, the group G denotes a functional group that can be transferred into the group XDof formula D: For example, a preferred precursor for the synthesis of the compounds of the formula D is the amino derivative of the formula N1 The compounds of formula N1 are reacted with a thiocarbonic acid derivative , in which X and Y are leaving groups, or with CS2to give the compounds of formula D. Preferred reagents for the process according to the invention for the transformation of compounds of the formula N1 into compounds of the formula D are carbon disulfide, thiophosgene, thiocarbonyl diimidazole, di-2-pyridyl thionocarbonate, bis(dimethylthiocarbamoyl) disulfide, dimethylthiocarbamoyl chloride and phenyl chlorothionoformate, very preferably thiophosgene. Another preferred pathway for the synthesis of isothiocyanates of the formula D includes the reaction of the N-hydroxycarboximidoyl chloride N2 with for example thiourea or a thiocarbonate. Compounds of formula D in which the terminal group XDdenotes -C^C-CN can be synthesized in analogy to processes described in DE 19831093 A1. Compounds of formula D in which the terminal group XDdenotes -C^C-NCS are prepared in accordance with a process described in M.S. Shvartsberg et al., Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya (1976), (10), 2292-5 (Scheme 3): the acetylenes 13 can be transferred into chlorides 14 by deprotonation and chlorination with N-chlorosuccinimide, which can be reacted with sodium amide to give the amines of formula N-3, from which said compounds of formula D (Scheme 3, D’) are obtainable using for example the known reagents listed above. P24-041 AT In the reactions shown in the schemes 1 to 3 above and below, reactions towards compounds of the formula D are exemplified in which the group denotes described processes by choice of suitable reaction conditions or by for example first reacting the compound 1 with a building block that carries the terminal group precursor G (scheme 1) instead of the wing group R'. Scheme 3: The described reactions 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 D. P24-041 AT In a preferred embodiment of the present invention, the compound of formula D is in which the occurring groups have the meanings given above for formula D, and t2 is 0, 1 or 2, t4 is 0 or 1, and t2+t4 is 1, 2 or 3, preferably 1 or 2. In formula D and its sub-formulae, in which RL, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, or cycloalkyl having 3 to 5 C atoms, XDdenotes -NCS, ZD1, ZD2, ZD3and ZD4, identically or differently, denote -CH=CH-, -CF=CF-, -C^C-, or a single bond, where in which P24-041 AT W denotes N, C-H, C-F or C-Cl, and Y1and Y2, identically or differently, denote H, Cl, F, methyl or ethyl. In the formulae D-1 and D-2, preferably t2 and t4 are 0 or 1 where t2 + t4 is 1 or 2. Preferred compounds of the formula D-1 are selected from the following sub-formulae: P24-041 AT P24-041 AT P24-041 AT P24-041 AT RDdenotes straight chain alkyl or alkoxy having 1 to 12 C atoms, or straight chain alkenyl or alkynyl or alkenyloxy or alkynyloxy having 2 to 12 C atoms, or branched or cyclic alkyl or alkoxy or alkenyl or alkenyloxy having 3 to 12 C atoms, more preferably straight chain alkyl having 1 to 7 C atoms or alkynyl having 2 to 7 C atoms, XDdenotes NCS, and which Y, identically or differently, denotes F, Cl or CH3, preferably F. more preferably denotes P24-041 AT L on each occurrence, identically or differently, denotes F, Cl, CH3or C2H5, and n is 1 or 2, preferably 1. Very preferred are the compounds of the formulae D-1-1, D-1-2, D-1-3, D-1-4, D-1-9, D-1-10, D-1-11, D-1-12, D-2-1, D-2-2, D-2-3, D-2-4, D-2-9, D-2-10, D-2-11, and D-2-12. In a preferred embodiment the medium according to the invention comprises one or more compounds selected from the group of compounds of the formulae I, II and III: R1denotes H, non-fluorinated alkyl or non-fluorinated alkoxy having 1 to 17, preferably 2 to 10 C atoms, or non-fluorinated alkenyl, non-fluorinated alkenyloxy or non-fluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C atoms, in which one or more CH2-groups may be replaced by preferably non-fluorinated alkyl or non-fluorinated alkenyl, n is 0, 1 or 2, , on each occurrence, independently of one another, denote P24-041 AT in which RL, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, preferably H, methyl or ethyl, particularly preferably in which one or more H atoms may be replaced by alkyl having 1 to 6 C atoms or F, in which RL, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, and wherein alternatively denotes preferably P24-041 AT , and in case n = 2, one of preferably denotes and the other preferably denotes and the other preferably denotes preferably , independently of one another, denote P24-041 AT more preferably denotes denotes H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17, preferably 2 to 10 C atoms, or unfluorinated alkenyl, unfluori- nated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C atoms, in which one or more CH2-groups may preferably unfluorinated alkyl or unfluorinated alkenyl, Z21denotes trans-CH=CH-, trans-CF=CF- or -C≡C-, preferably -C≡C- or trans-CH=CH-, and P24-041 AT in which RL, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, preferably H, methyl or ethyl, particularly preferably H, in which one or more H atoms may be replaced by alkyl having 1 to 6 C atoms or F, occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, preferably , independently of one another, denote P24-041 AT more preferably denotes H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17, preferably 2 to 10 C atoms, or unfluorinated alkenyl, unfluori- nated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C atoms, in which one or more CH2-groups may be replaced P24-041 AT preferably unfluorinated alkyl or unfluorinated alkenyl, one of Z31and Z32, preferably Z32; denotes trans-CH=CH-, trans-CF=CF- or -C≡C- and the other one, independently thereof, denotes -C≡C-, trans- CH=CH-, trans-CF=CF- or a single bond, preferably one of them, preferably Z32denotes -C≡C- or trans-CH=CH- and the other denotes a single bond, and , independently of one another, denote in which RL, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, preferably H, methyl or ethyl, particularly preferably H, in which one or more H atoms may be replaced by alkyl having 1 to 6 C atoms or F, P24-041 AT identically or differently, denotes H or alkyl having 1 to 6 C atoms, and wherein , preferably , independently of one another, denote more preferably P24-041 AT In the compounds of the formulae I, II and III, RLpreferably denotes H. In another preferred embodiment, in the compounds of formulae I, II and III, one or two groups RL, preferably one group RLis 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-1 to I-5: P24-041 AT in which L1, L2and L3on each occurrence, identically or differently, denote H or F, and the other groups have the respective meanings indicated above for formula I and preferably R1denotes unfluorinated alkyl having 1 to 7 C atoms or unfluorinated alkenyl having 2 to 7 C atoms. Preferably, the medium comprises one or more compounds selected from the compounds of the formula I-a and optionally one or more compounds selected from the compounds of the formula Cy-1 in which the occurring groups have the meanings given above for formula I-1. The total amount of compounds of the formula I-1 and / or Cy-I in the medium according to the invention is less than 10%, more preferably less than 5%, and in particular less than 2%. Particularly preferably, the medium contains no compound of formula Cy-1. The media preferably comprise one or more compounds of formula I-1, which are preferably selected from the group of the compounds of the formulae I-1a to I-1d, preferably of formula I-1b: P24-041 AT in which R1has the meaning indicated above for formula I and preferably denotes unfluorinated alkyl having 1 to 7 C atoms or unfluorinated alkenyl having 2 to 7 C atoms. The media preferably comprise one or more compounds of formula I-2, which are preferably selected from the group of the compounds of the formulae I-2a to I-2e, preferably of formula I-2c: P24-041 AT I-2e in which R1has the meaning indicated above for formula I and preferably denotes unfluorinated alkyl having 1 to 7 C atoms or unfluorinated alkenyl having 2 to 7 C atoms. The media preferably comprise one or more compounds of formula I-3, which are preferably selected from the group of the compounds of the formulae I-3a to I-3d , particularly preferably of formula I-3b: in which R1has the meaning indicated above for formula I and preferably denotes unfluorinated alkyl having 1 to 7 C atoms or unfluorinated alkenyl having 2 to 7 C atoms. P24-041 AT The media preferably comprise one or more compounds of formula I-4, which are preferably selected from the group of the compounds of the formulae I-4a to I-4e, particularly preferably of formula I-4b: in which R1has the meaning indicated above for formula I and preferably denotes unfluorinated alkyl having 1 to 7 C atoms or unfluorinated alkenyl having 2 to 7 C atoms. The media preferably comprise one or more compounds of formula I-5, which are preferably selected from the group of the compounds of the formulae I-5a to I-5d, particularly preferably of formula I-5b: I-5a P24-041 AT in which R1has the meaning indicated above for formula I and preferably denotes unfluorinated alkyl having 1 to 7 C atoms or unfluorinated alkenyl having 2 to 7 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-1 to II-3, preferably selected from the group of the compounds of the formulae II-1 and II-2: in which the occurring groups have the meanings given under formula II above and preferably R2denotes unfluorinated alkyl or alkoxy having 1 to 7 C atoms or unfluorinated alkenyl having 2 to 7 C atoms, P24-041 AT and one of and the other, independently denotes and preferably R2denotes CnH2n+1or CH2=CH-(CH2)Z, and n denotes an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. P24-041 AT The compounds of formula II-1 are preferably selected from the group of the compounds of the formulae II-1a to II-1e: in which R2has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH- (CH2)Z, and n denotes an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. P24-041 AT The compounds of formula II-2 are preferably selected from the group of the compounds of the formulae II-2a and II-2b: R2has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, n denotes an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The compounds of formula II-3 are preferably selected from the group of the compounds of the of formulae II-3a to II-3d:

[0002] P24-041 AT in which R2has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH- (CH2)Z, denotes an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The compounds of formula III are preferably selected from the group of the compounds of the formulae III-1 to III-6, more preferably of the formulae selected from the group of the compounds of the formulae III-1, III-2, III-3 and III-4, and particularly preferably of formula III-1: in which P24-041 AT Z31and Z32independently of one another denote trans-CH=CH- or trans-CF=CF-, preferably trans-CH=CH-, and in formula III-6 alternatively one of Z31and Z32may denote -C≡C- and the other groups have the meaning given above under formula III, and preferably R3denotes unfluorinated alkyl or alkoxy having 1 to 7 C atoms or unfluorinated alkenyl having 2 to 7 C atoms, and one of and the others, independently of one another, denote preferably P24-041 AT and preferably R3denotes CnH2n+1or CH2=CH-(CH2)Z, n denotes an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The compounds of formula III-1 are preferably selected from the group of the compounds of the formulae III-1a to III-1j, more preferably selected from the group of the compounds of the formulae III-1a, III-1b, III-1g and III-1h, particularly preferably of formula III-1b and / or III-1h: P24-041 AT in which P24-041 AT R3has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, n denotes an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The compounds of formula III-2 are preferably compounds of formula III-2a to III-2l, very preferably III-2b and / or III-2j: P24-041 AT R3has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, n denotes an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The compounds of formula III-5 are preferably selected from the compounds of formula III-5a: P24-041 AT R3has the meaning indicated above for formula III-5 and preferably denotes CnH2n+1, in which n denotes an integer in the range from 1 to 7, preferably in the range from 2 to 6. In a preferred embodiment of the present invention the medium comprises one or more compounds of the formula III selected from the group consisting of the formulae IIIa-1 to IIIa-4: in which R3has the meanings defined for formula III and preferably denotes straight chain alkyl having 1 to 7 C atoms or branched alkyl having 1 to 9 C atoms, in which one or more CH2-groups may be replaced by , P24-041 AT Very preferred are the compounds of the formulae IIIa-2 and IIIa-3. 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-1-1 to IIA-1-12, very preferably IIA-1-1 or IIA-1-2: P24-041 AT in which R1denotes alkyl or alkenyl having up to 7 C atoms, preferably ethyl, n-propyl, n- butyl or n-pentyl, n-hexyl, P24-041 AT RLon each occurrence, the same or differently, denotes alkyl or alkenyl having 1 to 5 C atoms, or cycloalkyl or cycloalkenyl each having 3 to 6 C atoms, preferably methyl, ethyl, n-propyl, n-butyl, isopropyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclopent-1-enyl, very preferably ethyl, and from which the compounds of formula II-1 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, in which s is 0 or 1, preferably 1, and preferably P24-041 AT , particularly preferably L4denotes H or alkyl having 1 to 6 C atoms, cycloalkyl having 3 to 6 C atoms or cycloalkenyl having 4 to 6 C atoms, preferably CH3, C2H5, n-C3H7, i-C3H7, cyclopropyl, cyclobutyl, cyclohexyl, cyclopent-1-enyl or cyclohex-1-enyl, and particularly preferably CH3, C2H5, cyclopropyl or cyclobutyl, X4denotes H, alkyl having 1 to 3 C atoms or halogen, preferably H, F or Cl, more preferably H or F and very particularly preferably F, R41to R44, independently of one another, denote unfluorinated alkyl or unfluorinated alkoxy, each having 1 to 15 C atoms, unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl, each having 2 to 15 C atoms, or cycloalkyl, alkylcycloalkyl, cycloalkenyl, alkylcycloalkenyl, alkylcycloalkyl- alkyl or alkylcycloalkenylalkyl, each having up to 15 C atoms, and alternatively one of R43and R44or both also denote H, preferably R41and R42, independently of one another, denote unfluorinated alkyl or unfluorinated alkoxy, each having 1 to 7 C atoms, or unfluorinated alkenyl, P24-041 AT unfluorinated alkenyloxy or unfluorinated alkoxyalkyl, each having 2 to 6 C atoms, particularly preferably R41denotes unfluorinated alkyl having 1 to 7 C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl, each having 2 to 6 C atoms, and particularly preferably R42denotes unfluorinated alkyl or unfluorinated alkoxy, each having 1 to 7 C atoms, and preferably R43and R44denote H, unfluorinated alkyl having 1 to 5 C atoms, unfluorinated cycloalkyl or cycloalkenyl having 3 to 7 C atoms, unfluorinated alkylcyclohexyl or unfluorinated cyclohexylalkyl, each having 4 to 12 C atoms, or unfluorinated alkylcyclohexylalkyl having 5 to 15 C atoms, particularly preferably cyclopropyl, cyclobutyl or cyclohexyl, and very particularly preferably at least one of R43and R44denotes n-alkyl, particularly preferably methyl, ethyl or n-propyl, and the other denotes H or n-alkyl, particularly preferably H, methyl, ethyl or n-propyl. Very preferably, the compounds of formula IV are selected from the compounds of the formula IV-1 in which R41and R42, identically or differently, denote alkyl having 2, 3, 4, 5 or 6 C atoms. 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: P24-041 AT in which L51denotes R51or X51, L52denotes R52or X52, R51and R52, independently of one another, denote H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17, preferably 2 to 10, C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C atoms, preferably alkyl or unfluorinated alkenyl, X51and X52, independently of one another, denote H, F, Cl, -CN, SF5, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms or fluorinated alkenyl, fluorinated alkenyloxy or fluorinated alkoxyalkyl having 2 to 7 C atoms, preferably fluorinated alkoxy, fluorinated alkenyloxy, F or Cl, and , independently of one another, denote P24-041 AT L61denotes R61and, in the case where Z61and / or Z62denote trans-CH=CH- or trans-CF=CF-, alternatively also denotes X61, L62denotes R62and, in the case where Z61and / or Z62denote trans-CH=CH- or trans-CF=CF-, alternatively also denotes X62, R61and R62, independently of one another, denote H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17, preferably 2 to 10, C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C atoms, preferably alkyl or unfluorinated alkenyl, X61and X62, independently of one another, denote F or Cl, -CN, SF5, fluorinated alkyl or alkoxy having 1 to 7 C atoms or fluorinated alkenyl, alkenyloxy or alkoxyalkyl having 2 to 7 C atoms, one of Z61and Z62denotes trans-CH=CH-, trans-CF=CF- or -C≡C- and the other, independently thereof, denotes trans-CH=CH-, trans-CF=CF- or a single bond, preferably one of them denotes -C≡C- or trans-CH=CH- and the other denotes a single bond, and P24-041 AT , independently of one another, denote and x denotes 0 or 1; L71denotes R71or X71, L72denotes R72or X72, R71and R72, independently of one another, denote H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17, preferably 2 to 10, C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C atoms, preferably alkyl or unfluorinated alkenyl, P24-041 AT X71and X72, independently of one another, denote H, F, Cl, -CN, -NCS, -SF5, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms or fluorinated alkenyl, unfluorinated or fluorinated alkenyloxy or unfluorinated or fluorinated alkoxyalkyl having 2 to 7 C atoms, preferably fluorinated alkoxy, fluorinated alkenyloxy, F or Cl, and Z71to Z73, independently of one another, denote trans-CH=CH-, trans-CF=CF-, - C≡C- or a single bond, preferably one or more of them denote a single bond, particularly preferably all denote a single bond and , independently of one another, denote R81and R82, independently of one another, denote H, unfluorinated alkyl or alkoxy having 1 to 15, preferably 2 to 10, C atoms or unfluorinated alkenyl, P24-041 AT alkenyloxy or alkoxyalkyl having 2 to 15, preferably 3 to 10, C atoms, preferably unfluorinated alkyl or alkenyl, one of Z81and Z82denotes trans-CH=CH-, trans-CF=CF- or -C≡C- and the other, independently thereof, denotes trans-CH=CH-, trans-CF=CF- or a single bond, preferably one of them denotes -C≡C- or trans-CH=CH- and the other denotes a single bond, and , independently of one another, denote L91denotes L92denotes R91and R92, independently of one another, denote H, unfluorinated alkyl or alkoxy having 1 to 15, preferably 2 to 10, C atoms or unfluorinated alkenyl, alkenyloxy or alkoxyalkyl having 2 to 15, preferably 3 to 10, C atoms, preferably unfluorinated alkyl or alkenyl, X91and X92, independently of one another, denote H, F, Cl, -CN, -NCS, -SF5, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms or fluorinated alkenyl, unfluorinated or fluorinated alkenyloxy or P24-041 AT unfluorinated or fluorinated alkoxyalkyl having 2 to 7 C atoms, preferably fluorinated alkoxy, fluorinated alkenyloxy, F or Cl, and Z91to Z93, independently of one another, denote trans-CH=CH-, trans-CF=CF-, - C≡C- or a single bond, preferably one or more of them denotes a single bond, and particularly preferably all denote a single bond, independently of one another, denote 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-1 to V-3, preferably of the formulae V-1 and / or V-2 and / or V-3, preferably of the formulae V-1 and V-2: P24-041 AT in which the occurring groups have the respective meanings indicated above for formula V and preferably R51denotes unfluorinated alkyl having 1 to 7 C atoms or unfluorinated alkenyl having 2 to 7 C atoms, R52denotes unfluorinated alkyl having 1 to 7 C atoms or unfluorinated alkenyl having 2 to 7 C atoms or unfluorinated alkoxy having 1 to 7 C atoms, X51and X52, independently of one another, denote F, Cl, -OCF3, -CF3, -CN or -SF5, preferably F, Cl, -OCF3or -CN. The compounds of the formula V-1 are preferably selected from the group of the compounds of the formulae V-1a to V-1d, preferably V-1c and V-1d : P24-041 AT in which the parameters have the respective meanings indicated above for formula V-1 and in which Y51and Y52, in each case independently of one another, denote H or F, and preferably R51denotes alkyl or alkenyl, and X51denotes F, Cl or -OCF3. The compounds of the formula V-2 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-2g: P24-041 AT where in each case the compounds of the formula V-2a are excluded from the compounds of the formulae V-2b and V-2c, the compounds of the formula V-2b are excluded from the compounds of the formula V-2c and the compounds of the formula V-2f are excluded from the compounds of the formula V-2g, and in which the parameters have the respective meanings indicated above for formula V-1 and in which Y51and Y52, in each case independently of one another, denote H or F, and preferably Y51and Y52denotes H and the other denotes H or F, preferably likewise denotes H. The compounds of the formula V-3 are preferably compounds of the formula V-3a: V-3a in which the parameters have the respective meanings indicated above for formula V-1 and in which preferably X51denotes F, Cl, preferably F, X52denotes F, Cl or -OCF3, preferably -OCF3. P24-041 AT The compounds of the formula V-1a are preferably selected from the group of the compounds of the formulae V-1a-1 and V-1a-2: in which R51has the meaning indicated above and preferably denotes CnH2n+1, in which n denotes an integer in the range from 1 to 7, preferably in the range from 1 to 6 and particularly preferably 3 to 5. The compounds of the formula V-1b are preferably compounds of the formula V-1b-1: in which R51has the meaning indicated above and preferably denotes CnH2n+1, in which n denotes an integer in the range from 1 to 7, preferably in the range from 1 to 6 and particularly preferably 3 to 5. The compounds of the formula V-1c are preferably selected from the group of the compounds of the formulae V-1c-1 to V-1c-4, particularly preferably selected from the group of the compounds of the formulae V-1c-1 and V-1c-2: P24-041 AT in which R51has the meaning indicated above and preferably denotes CnH2n+1, in which n denotes an integer in the range from 1 to 7, preferably in the range from 1 to 6 and particularly preferably 3 to 5. The compounds of the formula V-1d are preferably selected from the group of the compounds of the formulae V-1d-1 and V-1d-2, particularly preferably the compound of the formula V-1d-2: in which R51has the meaning indicated above and preferably denotes CnH2n+1, in which P24-041 AT denotes an integer in the range from 1 to 7, preferably in the range from 1 to 6 and particularly preferably 3 to 5. The compounds of the formula V-2a are preferably selected from the group of the compounds of the formulae V-2a-1 and V-2a-2, particularly preferably the compounds of the formula V-2a-1: in which R51has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R52has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 1 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. Preferred combinations of R51with R52, in particular in the case of formula V-2a-1, are (CnH2n+1and CmH2m+1), (CnH2n+1and O-CmH2m+1), (CH2=CH-(CH2)Zand CmH2m+1), (CH2=CH-(CH2)Zand O-CmH2m+1) and (CnH2n+1and (CH2)Z-CH=CH2). Preferred compounds of the formula V-2b are the compounds of the formula V-2b-1: V-2b-1 in which P24-041 AT R51has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R52has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 1 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combination of R51with R52here is, in particular, CnH2n+1and CmH2m+1. Preferred compounds of the formula V-2c are the compounds of the formula V-2c-1: in which R51has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R52has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 1 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combination of (R51and R52) here is, in particular, (CnH2n+1and CmH2m+1). Preferred compounds of the formula V-2d are the compounds of the formula V-2d-1: in which R51has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R52has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which P24-041 AT n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 1 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combination of (R51and R52) here is, in particular, (CnH2n+1and CmH2m+1). Preferred compounds of the formula V-2e are the compounds of the formula V-2e-1: in which R51has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R52has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combination of (R51and R52) here is, in particular, (CnH2n+1and O-CmH2m+1). Preferred compounds of the formula V-2f are the compounds of the formula V-2f-1: in which R51has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R52has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which P24-041 AT n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combinations of (R51and R52) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1), particularly preferably (CnH2n+1and CmH2m+1). Preferred compounds of the formula V-2g are the compounds of the formula V-2g-1: V-2g-1 in which R51has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R52has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combinations of (R51and R52) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1), particularly preferably (CnH2n+1and O-CmH2m+1). The compounds of the formula VI are preferably selected from the group of the compounds of the formulae VI-1 to VI-5: P24-041 AT in which Z61and Z62denote -C^C-, trans-CH=CH- or trans-CF=CF-, preferably -C^C- or trans-CH=CH-, and the other occurring groups and parameters have the meaning given above under formula VI, and preferably R61and R62, independently of one another, denote H, unfluorinated alkyl or alkoxy having 1 to 7 C atoms or unfluorinated alkenyl having 2 to 7 C atoms, X62denotes F, Cl, -OCF3or -CN, The compounds of the formula VI-1 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: in which R61has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and P24-041 AT R62has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combinations of (R61and R62) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1), in the case of formula VI-1a particularly preferably (CnH2n+1and CmH2m+1) and in the case of formula VI-1b particularly preferably (CnH2n+1and O-CmH2m+1). The compounds of the formula VI-3 are preferably selected from the compounds of the formula VI-3a to VI-3e: P24-041 AT VI-3e in which the parameters have the meaning given above under formula VI-3 and preferably R61has the meaning indicated above and preferably denotes CnH2n+1, in which n denotes an integer in the range from 1 to 7, preferably in the range from 1 to 5, and X62denotes -F, -Cl, -OCF3, or -CN. The compounds of the formula VI-4 are preferably selected from compounds of the for- mulae VI-4a to VI-4e: P24-041 AT in which the parameters have the meaning given above under formula VI-4 and preferably R61has the meaning indicated above and preferably denotes CnH2n+1, in which n denotes an integer in the range from 1 to 7, preferably in the range from 1 to 5, and X62denotes F, Cl, OCF3, or -CN. The compounds of the formula VI-5 are preferably selected from the compounds of the formulae VI-5a to VI-5d, preferably VI-5b: in which the parameters have the meaning given above under formula VI-5 and preferably P24-041 AT R61has the meaning indicated above and preferably denotes CnH2n+1, in which n denotes an integer in the range from 1 to 7, preferably in the range from 1 to 5, and X62denotes -F, -Cl, -OCF3, or -CN, particularly preferably -OCF3. The compounds of the formula VII are preferably selected from the group of the compounds of the formulae VII-1 to VII-6: P24-041 AT where the compounds of the formula VII-5 are excluded from the compounds of the formula VII-6, and in which the parameters have the respective meanings indicated above for formula VII, Y71, Y72, Y73independently from one another, denote H or F, and preferably R71denotes unfluorinated alkyl or alkoxy, each having 1 to 7 C atoms, or unfluorinated alkenyl having 2 to 7 C atoms, R72denotes unfluorinated alkyl or alkoxy, each having 1 to 7 C atoms, or unfluorinated alkenyl having 2 to 7 C atoms, X72denotes F, Cl; NCS or -OCF3, preferably F or NCS, and particularly preferably R71has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R72has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The compounds of the formula VII-1 are preferably selected from the group of the compounds of the formulae VII-1a to VII-1d: P24-041 AT in which X72has the meaning given above for formula VII-2 and R71has the meaning indicated above and preferably denotes CnH2n+1, in which n denotes an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2, and X72preferably denotes F. The compounds of the formula VII-2 are preferably selected from the group of the compounds of the formulae VII-2a and VII-2b, particularly preferably of the formula VII- 2a: VII-2a P24-041 AT VII-2b in which R71has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R72has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combinations of (R71and R72) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1), particularly preferably (CnH2n+1and CmH2m+1). The compounds of the formula VII-3 are preferably compounds of the formula VII-3a: VII-3a in which R71has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R72has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. P24-041 AT The preferred combinations of (R71and R72) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1), particularly preferably (CnH2n+1and CmH2m+1). The compounds of the formula VII-4 are preferably compounds of the formula VII-4a: VII-4a in which R71has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R72has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combinations of (R71and R72) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1), particularly preferably (CnH2n+1and CmH2m+1). The compounds of the formula VII-5 are preferably selected from the group of the compounds of the formulae VII-5a and VII-5b, more preferably of the formula VII-5a: in which R71has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and P24-041 AT R72has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combinations of (R71and R72) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1), particularly preferably (CnH2n+1and CmH2m+1). The compounds of the formula VII-6 are preferably selected from the group of the compounds of the formulae VII-6a and VII-6b: in which R71has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R72has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combinations of (R71and R72) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1), particularly preferably (CnH2n+1and CmH2m+1). P24-041 AT The compounds of the formula VII-7 are preferably selected from the group of the compounds of the formulae VII-7a to VII-7d: in which R71has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, X72denotes F, -OCF3or -NCS, n denotes an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The compounds of the formula VIII are preferably selected from the group of the compounds of the formulae VIII-1 to VIII-3, more preferably these compounds of the formula VIII predominantly consist, even more preferably essentially consist and very particularly preferably completely consist thereof: P24-041 AT in which one of Y81and Y82denotes H and the other denotes H or F, and R81has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R82has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combinations of (R81and R82) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1), particularly preferably (CnH2n+1and CmH2m+1). The compounds of the formula VIII-1 are preferably selected from the group of the compounds of the formulae VIII-1a to VIII-1c: P24-041 AT in which R81has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R82has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combinations of (R81and R82) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1), particularly preferably (CnH2n+1and CmH2m+1). The compounds of the formula VIII-2 are preferably compounds of the formula VIII-2a: in which R81has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R82has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. P24-041 AT The preferred combinations of (R81and R82) here are, in particular, (CnH2n+1and CmH2m+1), (CnH2n+1and O-CmH2m+1) and (CH2=CH-(CH2)Zand CmH2m+1), particularly preferably (CnH2n+1and CmH2m+1). The compounds of the formula VIII-3 are preferably compounds of the formula VIII-3a: VIII-3a in which R81has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R82has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combinations of (R81and R82) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1). The compounds of the formula IX are preferably selected from the group of the compounds of the formulae IX-1 to IX-3: P24-041 AT in which the parameters have the respective meaning indicated above under formula IX and preferably one of and in which R91has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R92has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combinations of (R91and R92) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1). The compounds of the formula IX-1 are preferably selected from the group of the compounds of the formulae IX-1a to IX-1e: P24-041 AT in which the parameters have the meaning given above and preferably R91has the meaning indicated above and preferably denotes CnH2n+1, and n denotes an integer in the range from 0 to 15, preferably in the range from 1 to 7 and particularly preferably 1 to 5, and X92preferably denotes F or Cl. The compounds of the formula IX-2 are preferably selected from the group of the compounds of the formulae IX-2a and IX-2b: in which R91has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and P24-041 AT R92has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combination of (R91and R92) here is, in particular, (CnH2n+1and CmH2m+1). The compounds of the formula IX-3 are preferably compounds of the formulae IX-3a and IX-3b: in which R91has the meaning indicated above and preferably denotes CnH2n+1or CH2=CH-(CH2)Z, and R92has the meaning indicated above and preferably denotes CmH2m+1or O-CmH2m+1or (CH2)Z-CH=CH2, and in which n and m, independently of one another, denote an integer in the range from 1 to 7, preferably in the range from 2 to 6 and particularly preferably 3 to 5, and z denotes 0, 1, 2, 3 or 4, preferably 0 or 2. The preferred combinations of (R91and R92) here are, in particular, (CnH2n+1and CmH2m+1) and (CnH2n+1and O-CmH2m+1), particularly preferably (CnH2n+1and O-CmH2m+1). P24-041 AT In a preferred embodiment of the present invention the medium comprises one or more compounds of formula X in which R101denotes H, alkyl or alkoxy having 1 to 15, preferably 2 to 10, C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C atoms, preferably alkyl or alkenyl, X101denotes H, F, Cl, -CN, SF5, NCS, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms or fluorinated alkenyl, fluorinated alkenyloxy or fluorinated alkoxyalkyl having 2 to 7 C atoms, preferably fluorinated alkoxy, fluorinated alkenyloxy, F, Cl or NCS, particularly preferably NCS, Y101denotes methyl, ethyl or Cl, Y102denotes H, methyl, ethyl, F or Cl, preferably H or F, Z101, Z102identically or differently, denote a single bond, -CH=CH-, -CF=CF- or -C^C-, independently of one another, denote P24-041 AT and where , and n is 0 or 1. Preferably, the compounds of formula X are selected from the sub-formulae X-1 and X-2 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-1-1 to X-1-9 P24-041 AT In which R101denotes alkyl having 1 to 7 C atoms. In a preferred embodiment, the medium according to the invention comprises one or more compounds of formula XI P24-041 AT in which RSdenotes H, alkyl or alkoxy having 1 to 12 C atoms, or alkenyl, alkenyloxy or alkoxyalkyl having 2 to 12 C atoms, in which one or , or more H atoms may be replaced by F, , on each occurrence, independently of one another, denote in which RL, on each occurrence identically or differently, denotes H, Cl or straight-chain, branched or cyclic alkyl having 1 to 6 C atoms, LS1, LS2identically or differently, denote H, Cl or F, RS1, RS2, identically or differently, denote H, alkyl or alkenyl, having up to 6 C atoms, or cyclopropyl, cyclobutyl, cyclopentenyl, or cyclopentyl, RTh1, RTh2identically or differently, denote H, alkyl or alkenyl or alkoxy, having up to 6 C atoms, or cyclopropyl, cyclobutyl, cyclopentenyl or cyclopentyl, P24-041 AT ZS1, ZS2, ZS3identically or differently, denote -CH=CH-, -CH=CF-, -CF=CH-, -CF=CF-, -C^C-, or a single bond, a, b identically or differently, are 0 or 1. Preferably, the compounds of formula XI are selected from the group of compounds of the formulae XI-1 to XI-24: P24-041 AT P24-041 AT P24-041 AT in which the occurring groups have the meanings given above for formula XI and preferably RSdenotes alkyl or alkenyl having 2 to 6 C atoms, in which one or more RS1and RS2identically or differently, denote H or alkyl having 1 to 6 C atoms, preferably H, RS3denotes H, F or alkyl, having up to 6 C atoms, or cyclopropyl, preferably H, F or ethyl, very preferably H, LS1and LS2identically or differently, denote H or F, preferably F. P24-041 AT Preferably, the medium comprises one or more compounds of formula XII in which R12denotes H, alkyl or alkoxy having 1 to 12 C atoms, or alkenyl, alkenyloxy or alkoxyalkyl having 2 to 12 C atoms, in which one or more CH2-groups may be replaced denotes a group RP, RPdenotes halogen, CN, NCS, RF, RF-O- or RF-S-, wherein RFdenotes fluorinated alkyl or fluorinated alkenyl having up to 9 C atoms, Z121, Z122identically or differently, denote -CH=CH-, -CF=CF-, -CH=CF- , -CF=CH-, -C^C- or a single bond, preferably -C^C- or a single bond, X1, X2, X3and X4identically or differently, denote Cl or F, preferably F, t is 0 or 1, and denote a radical selected from the following groups: a) the group consisting of 1,4-phenylene, 1,4-naphthylene, and 2,6- 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, wherein tetrafluoro-1,4-phenylene is excluded, b) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, bicyclo[1.1.1]pentane-1,3-diyl, 4,4´-bicyclohexylene, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, in which one or more non-adjacent CH2groups may be replaced by -O- and / or -S- and in which one or more H atoms may be replaced by F, P24-041 AT c) the group consisting of thiophene-2,5-diyl, thieno[3,2-b]thiophene-2,5- diyl, selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF5or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkyl- carbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, and where the compounds of the formula XII are excluded from the compounds of the formulae I II and III. The compounds of formula XII are preferably selected from the compounds of the sub- formulae XII-1 to XII-11: P24-041 AT in which P24-041 AT L1, L2and L3identically or differently, denote H, F, Cl, methyl, ethyl, n-propyl, isopropyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl, and R12, X1, X2, X3and X4have the meanings given above for formula XII. Very preferably, the medium comprises a compound of formula XII-3, in which the occurring groups have the meanings given above and particularly preferably L1denotes H, X1, X2, X3and X4denote F and R12denotes alkyl having 1 to 7 C atoms. The medium according to the invention preferably comprises one or more compounds of the formula XIII in which R13denotes H, alkyl or alkoxy having 1 to 12 C atoms, or alkenyl, alkenyloxy or alkoxyalkyl having 2 to 12 C atoms, in which one or more CH2-groups may be replaced group RP, RPdenotes halogen, CN, NCS, RF, RF-O- or RF-S-, wherein RFdenotes fluorinated alkyl or fluorinated alkenyl having up to 9 C atoms, Z131, Z132, Z133identically or differently, denote -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C^C- or a single bond, preferably -C^C- or a single bond, X1, X2identically or differently, denote H, Cl, F, CH3or C2H5, preferably H or F, Y1, Y2, Y3, Y4, identically or differently, denote H, F, Cl, or straight chain or branched or cyclic alkyl, alkenyl, alkoxy or alkenyloxy, each having up to 12 C atoms, where at least one of Y1, Y2, Y3and Y4is different from F, s is 0, 1 or 2, preferably 0 or 1, t is 0, 1 or 2, preferably 0 or 1, and s + t is 0, 1 or 2, preferably 0 or 1, P24-041 AT denote a radical selected from the following groups: a) the group consisting of 1,4-phenylene, 1,4-naphthylene, and 2,6- 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-1,4-cyclohexylene, 1,4-cyclohexenylene, bicyclo[1.1.1]pentane-1,3-diyl, 4,4´-bicyclohexylene, bicyclo[2.2.2]octane- 1,4-diyl, spiro[3.3]heptane-2,6-diyl, in which one or more non-adjacent CH2groups 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-2,5-diyl, thieno[3,2-b]thiophene-2,5-diyl, selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF5or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms. In a preferred embodiment of the present invention, the compounds of formula XIII are selected from the compounds of the formulae XIII-1 to XIII-20, very preferably from the compounds of the formulae XIII-1 to XIII-13: P24-041 AT P24-041 AT P24-041 AT in which the occurring groups have the meanings indicated above for formula XIII and its sub-formulae and preferably R13denotes alkyl having 1 to 7 C atoms, Y1, Y2, Y3, and Y4, identically or differently, denote H, F, Cl, methyl, ethyl, n-propyl, isopropyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl, and more preferably Y1and Y2independently denote H or F, in particular H, and Y3and Y4very preferably denote H, and L1and L2, identically or differently, very preferably denote H, F, methyl or ethyl, in particular H. Preferably, the medium according to the invention comprises one or more compounds of formula T in which P24-041 AT RTdenotes halogen, CN, NCS, RF, RF-O- or RF-S-, wherein RFdenotes fluorinated alkyl or fluorinated alkenyl having up to 12 C atoms, on each occurrence, independently of one another, denote L4and L5identically or differently, denote F, Cl or straight-chain or branched or cyclic alkyl or alkenyl each having up to 12 C atoms; ZT3, ZT4identically or differently, denote -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C^C- or a single bond, and t is 0 or 1. 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: T-1a P24-041 AT in which have the meanings given above and n is 1, 2, 3, 4, 5 ,6 or 7, preferably 1, 2, 3 or 4, particularly preferably 1. 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: P24-041 AT in which n is 1, 2, 3 or 4, preferably 1. Preferred compounds of formula T-2a are selected from the group of compounds of the following sub-formulae: P24-041 AT in which n is 1, 2, 3 or 4, preferably 1. Preferred compounds of formula T-3a are selected from the group of compounds of the following sub-formulae: P24-041 AT in which n is 1, 2, 3 or 4, preferably 1. Very preferably, the medium according to the invention comprises one or more compounds of formula T-1a-5. In an embodiment, the medium according to the invention comprises one or more compounds of formula I, II, III, IV, V, VI, VII, VIII, IX, X in which the radical R1, R2, R3, R41, R42, R51, R52, R61, R62, R71, R72, R81, R82, R91, R92, R101, R102and RS, respectively, is a cyclic alkyl group. Very preferred compounds comprising a cyclic alkyl group are selected from the compounds of the formulae Cy-1 to Cy-14 P24-041 AT P24-041 AT In a preferred embodiment, the medium according to the invention comprises a compound of formula N in which RNdenotes H, alkyl or alkoxy having 1 to 12 C atoms, or alkenyl, alkenyloxy or alkoxyalkyl having 2 to 12 C atoms, in which one or more CH2-groups may be replaced denotes a group RP, RPdenotes halogen, CN, NCS, RF, RF-O- or RF-S-, wherein RFdenotes fluorinated alkyl having 1 to 9 C atoms or fluorinated alkenyl having 2 to 9 C atoms, ZN1and ZN2,identically or differently, denote -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C^C- or a single bond, preferably -C^C- or a single bond, W denotes N, C-F or C-Cl, X1and X2, identically or differently, denote H, Cl, F, methyl or ethyl, P24-041 AT denote a radical selected from the following groups: a) the group consisting of 1,4-phenylene, 1,4-naphthylene, and 2,6-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-1,4-cyclohexylene, 1,4-cyclohexenylene, bicyclo- [1.1.1]pentane-1,3-diyl, 4,4´-bicyclohexylene, bicyclo[2.2.2]octane-1,4-diyl or spiro[3.3]heptane-2,6-diyl, in which one or more non-adjacent CH2groups 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-2,5-diyl, thieno[3,2-b]thiophene-2,5-diyl or selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by RL, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF5or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, and n is 0, 1 or 2. The compound of formula N is preferably selected from the group consisting of the formulae N-1, N-2 and N-3: P24-041 AT have the respectivemeanings given above for formula N. In formula N and its sub-formulae N-1, N-2 and N-3, preferably in which RL, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, preferably H, methyl or ethyl, particularly preferably H, L denotes F or alkyl having 1 to 6 C atoms, and r is 0, 1, 2, 3, 4, 5 or 6, preferably 0 or 1, P24-041 AT In a preferred embodiment, in formula N and its sub-formulae the radicals X1and X2both denote H. In a preferred embodiment, in formula N and its sub-formulae the radical X1denotes H and the radical X2denotes F or Cl. In a preferred embodiment, in formula N and its sub-formulae the radical X1denotes F or Cl and the radical X2denotes H. In a preferred embodiment, in formula N and its sub-formulae the radicals X1and X2denote F or Cl, preferably both F. The compounds of the formulae N-1, N-2 and N-3 are preferably selected from the group consisting of the formulae N-1-1 to N-1-10, N-2-1 to N-2-10 and N-3-1 to N-3-10: P24-041 AT P24-041 AT P24-041 AT P24-041 AT P24-041 AT in which RN, X1and X2have the meanings given above and L, on each occurrence identically or differently denotes H, F, methyl, ethyl or cyclopropyl. In a preferred embodiment, the medium according to the invention comprises a compound of formula NI NI n, have the respective meaningsgiven in claim 1 for formula N. The compounds of formula NI are preferably selected from the compounds of the formulae NI-1 and NI-2 P24-041 AT given abovefor formula N, Y1and Y2, identically or differently, denote H, F or Cl, and t is 0 or 1.In the compounds of formula L1and L2, identically or differently, denote F, Cl or straight chain or branched or cyclic alkyl or alkenyl each having up to 12 C atoms. In the compounds of formula NI or NI-1 or NI-2, ZN1and ZN2, identically or differently, preferably denote -C^C- or a single bond. P24-041 AT In a preferred embodiment of the present invention, the compounds of formula NI-1 and NI-2 are selected from the compounds of the formulae NI-1-1 to NI-1-12 and NI-2- 1 to NI-2-12 P24-041 AT P24-041 AT P24-041 AT in which L1, L2and L3identically or differently, denote H, F, Cl, methyl, ethyl, n-propyl, isopropyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl, and

[0003] P24-041 AT RN, Y1and Y2have the meanings given above for formula N-1 and N-2, and in which P24-041 AT In a preferred embodiment, in the compounds of formula NI and its sub-formulae, one or both of Y1and Y2denote H, preferably both. In another preferred embodiment, in the compounds of formula N and its sub-formulae both of Y1and Y2denote F. Preferably, the medium according to the invention comprises one or more compounds of formula UI in which RUdenotes H, straight-chain or branched non-fluorinated alkyl having 1 to 12 C atoms or non-fluorinated alkenyl having 2 to 12 C atoms, in which one or more CH2-groups may be replaced where one or more non-adjacent CH2-groups may be replaced by O, or denotes a group RP, RPdenotes halogen, CN, NCS, fluorinated alkyl, RF-O- or RF-S-, wherein RFdenotes fluorinated alkyl or fluorinated alkenyl having up to 9 C atoms, ZU1denotes -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C^C- or -C^C-C^C-, preferably -CF=CF- or -C^C-, XU1, XU2, identically or differently, denote Cl or F, preferably F. denote a radical selected from the following groups: a) the group consisting of 1,4-phenylene, 1,4-naphthylene, and 2,6-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-1,4-cyclohexylene, 1,4-cyclohexenylene, tetralin- 2,6-diyl, tetralin-5,8-diyl, decalin-2,6-diyl, bicyclo[1.1.1]pentane-1,3-diyl, 4,4´- bicyclohexylene, bicyclo[2.2.2]octane-1,4-diyl, and spiro[3.3]heptane-2,6-diyl, in which one or two CH groups may be replaced by N, one or more non-adjacent P24-041 AT CH2groups may be replaced by -O- and / or -S- and in which one or more H atoms may be replaced by L, c) the group consisting of thiophene-2,5-diyl, thieno[3,2-b]thiophene-2,5-diyl, selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF5or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy each having 1 to 12 C atoms, u is 0 or 1, v is 0 or 1, with the proviso that not both denote optionally fluorinated 1,4-phenylene and where the compounds of the formula UI and its sub- formulae are excluded from the compounds of the formulae I, II and III. The compounds of formula UI are preferably selected from the group of compounds consisting of the formulae UI-1, UI-2 and UI-3: given abovefor formula UI, and where in formula UI-3 at least one and P24-041 AT denotes trans-1,4-cyclohexylene, 1,4-cyclohexenylene, tetralin-2,6-diyl, tetralin-5,8-diyl, decalin-2,6-diyl, bicyclo[1.1.1]pentane-1,3-diyl, 4,4´-bicyclohexylene, bicyclo[2.2.2]octane-1,4-diyl, or spiro[3.3]heptane-2,6-diyl, in which one or two CH groups may be replaced by N, one or more non-adjacent CH2groups may be replaced by -O- and / or -S- and in which one or more H atoms may be replaced by L, wherein L, on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF5or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkyl carbonyloxy or alkoxycarbonyloxy each having 1 to 12 C atoms, and preferably XU1and XU2denote F, RUpreferably denotes straight chain or branched or cyclic alkyl or alkenyl having 1 to 7 C atoms, or fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms, and identically or differently, preferably denote , occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, P24-041 ATor denote which one or more H atoms may bereplaced by alkyl having 1 to 6 C atoms or F. in which RLdenotes H or alkyl having 1 to 6 C atoms. Preferred compounds of formula UI are selected from the following sub-formulae: P24-041 AT in which RUhas the meanings given above and preferably denotes straight chain or branched alkyl having 1 to 7 C atoms, in particular methyl, ethyl, n-propyl, n-butyl, n- pentyl, n-hexyl or n-heptyl. The liquid crystal medium according to the invention preferably comprises one or more compounds of the formula UII P24-041 AT in which RUdenotes H, straight-chain or branched alkyl having 1 to 12 C atoms or alkenyl having 2 to 12 C atoms, in which one or more CH2-groups may be replaced by one or more non-adjacent CH2-groups may be replaced by O, or a group RP, RPdenotes halogen, CN, NCS, RF-, RF-O- or RF-S-, wherein RFdenotes fluorinated alkyl or fluorinated alkenyl having up to 9 C atoms, ZU1, ZU2identically or differently, denote -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C^C-, -C^C-C^C- or a single bond, preferably -CF=CF-, -C^C- or a single bond, very preferably -C^C- or a single bond, XU1, XU2, identically or differently, denote Cl or F, preferably F, denote a radical selected from the following groups: a) the group consisting of 1,4-phenylene, 1,4-naphthylene, and 2,6-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-1,4-cyclohexylene, 1,4-cyclohexenylene, tetralin- 2,6-diyl, tetralin-5,8-diyl, decalin-2,6-diyl, bicyclo[1.1.1]pentane-1,3-diyl, 4,4´- bicyclohexylene, bicyclo[2.2.2]octane-1,4-diyl, and spiro[3.3]heptane-2,6-diyl, in which one or two CH groups may be replaced by N, one or more non-adjacent CH2groups may be replaced by -O- and / or -S- and in which one or more H atoms may be replaced by L, c) the group consisting of thiophene-2,5-diyl, thieno[3,2-b]thiophene-2,5-diyl, selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF5or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy each having 1 to 12 C atoms, and u is 0, 1 or 2, preferably 1, P24-041 AT where the compounds of formula UI are excluded from the compounds of formula UII, and where the compounds of the formula UII and its sub-formulae are excluded from the compounds of the formulae I, II, and III. The medium preferably comprises one or more compounds of the formula UI and one or more compounds of the formula UII. Preferably, the compounds of the formula UII are selected from the compounds of the formulae UII-1, UII-2 and UII-3, preferably UII-1 and UII-2, in particular UII-1: in which the occurring groups have the meanings given above for formula UII and P24-041 AT XU1and XU2denote F, and RUpreferably denotes straight chain or branched or cyclic alkyl or alkenyl having 1 to 7 C atoms, or fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms. Very preferred compounds of formula UII are selected from the following sub-formulae: in which RUhas the meanings given above and preferably denotes straight chain or branched alkyl having 1 to 7 C atoms, in particular methyl, ethyl, n-propyl, n-butyl, n- pentyl, n-hexyl or n-heptyl. The medium according to the invention preferably comprises one or more compounds of the formulae GF-1-1 to GF-5-1: P24-041 AT P24-041 AT in which RGdenotes straight chain or branched alkyl having 1 to 7 C atoms, in particular methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl or 2-methylbut-1-yl. 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 1 ^m-1to 150 ^m-1, preferably in the range of from 10 ^m-1to 100 ^m-1. 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 P24-041 AT 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-811, R- and S-1011, R- and S-2011, R- and S-3011, R- and S-4011, 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 1-5, 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 (1,4:3,6-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 CH2groups are substituted by alkyl or alkoxy; amino acids, such as, for example, alanine, valine, phenylglycine or phenylalanine, or sequences of from 1 to 5 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 DE 3425503, P24-041 AT DE 3534777, DE 3534778, DE 3534779 and DE 3534780, DE 4342280, EP 01038941 and DE 19541820. 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: in which Ra11, Ra12and Rb12, independently of one another, denote alkyl having 1 to 15 C atoms, in which, in addition, one or more non-adjacent CH2groups may each be replaced, independently of one another, by -C(Rz)=C(Rz)-, -C^C-, -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that O and / or S atoms are not linked directly to one another, and in which, in addition, P24-041 AT one or more H atoms may each be replaced by F, Cl, Br, I or CN, preferably alkyl, more preferably n-alkyl, with the proviso that Ra12is different from Rb12, Ra21and Ra22, independently of one another, denote alkyl having 1 to 15 C atoms, in which, in addition, one or more non-adjacent CH2groups may each be replaced, independently of one another, by -C(Rz)=C(Rz)-, -C^C-, -O-, - S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that O and / or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F, Cl, Br, I or CN, preferably both are alkyl, more preferably n-alkyl, Ra31, Ra32and Rb32, independently of one another, denote straight-chain or branched alkyl having 1 to 15 C atoms, in which, in addition, one or more non- adjacent CH2groups may each be replaced, independently of one another, by -C(Rz)=C(Rz)-, -C^C-, -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that O and / or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F, Cl, Br, I or CN, preferably alkyl, more preferably n-alkyl, with the proviso that Ra32is different from Rb32; Rzdenotes H, CH3, F, Cl, or CN, preferably H or F, R8has one of the meanings of Ra11given above, preferably alkyl, more preferably n-alkyl having 1 to 15 C atoms, Z8denotes- C(O)O-, CH2O, CF2O or a single bond, preferably -C(O)O-, A11is defined as A12below, or alternatively denotes P24-041 AT A12denotes in which L12on each occurrence, independently of one another, denotes halogen, CN, or alkyl, alkenyl, alkoxy or alkenyloxy having up to 12 C atoms and in which one or more H atoms are optionally replaced with halogen, preferably methyl, ethyl, Cl or F, particularly preferably F, A21denotes A22has the meanings given for A12 P24-041 AT A31has the meanings given for A11, or alternatively denotes A32has the meanings given for A12. n2 on each occurrence, identically or differently, is 0, 1 or 2, and n3 is 1, 2 or 3, and r is 0, 1, 2, 3 or 4. Particular preference is given to dopants selected from the group consisting of the compounds of the following formulae: P24-041 AT in which m is, on each occurrence, identically or differently, an integer from 1 to 9 and n is, on each occurrence, identically or differently, an integer from 2 to 9. Particularly preferred compounds of formula A are compounds of formula A-III. P24-041 AT Further preferred dopants are derivatives of the isosorbide, isomannitol or isoiditol of the following formula A-IV: (dianhydrosorbitol), (dianhydromannitol), or (dianhydroiditol), preferably dianhydrosorbitol, and chiral ethane diols, such as, for example, diphenylethanediol (hydrobenzoin), in particular mesogenic hydrobenzoin derivatives of the following formula A-V: P24-041 AT including the (S,S) enantiomers, which are not shown, in which are each, independently of one another, 1,4-phenylene, which may also be mono-, di- or trisubstituted by L, or 1,4-cyclo- hexylene, L is H, F, Cl, CN or optionally halogenated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkoxycarbonyloxy having 1-7 carbon atoms, c is 0 or 1, X is CH2or -C(O)-, Z0is -COO-, -OCO-, -CH2CH2- or a single bond, and R0is alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkylcarbonyloxy having 1-12 carbon atoms. Examples of compounds of formula A-IV are: P24-041 AT P24-041 AT The compounds of the formula A-IV are described in WO 98 / 00428. The compounds of the formula A-V are described in GB-A-2,328,207. Very particularly preferred dopants are chiral binaphthyl derivatives, as described in WO 02 / 94805, chiral binaphthol acetal derivatives, as described in WO 02 / 34739, chiral TADDOL derivatives, as described in WO 02 / 06265, and chiral dopants having at least one fluorinated bridging group and a terminal or central chiral group, as described in WO 02 / 06196 and WO 02 / 06195. Particular preference is given to chiral compounds of the formula A-VI A-VI in which X1, X2, Y1and Y2are each, independently of one another, F, Cl, Br, I, CN, SCN, SF5, straight-chain or branched alkyl having from 1 to 25 carbon atoms, which is unsubstituted or monosubstituted or polysubstituted by F, Cl, Br, I or CN and in which, in addition, one or more non-adjacent CH2groups may each, independently of one another, be replaced by -O-, -S-, -NH-, -NRx-, -CO-, P24-041 AT -COO-, -OCO-, -OCOO-, -S-CO-, -CO-S-, -CH=CH- or -C^C- in such a way that O and / or S atoms are not bonded directly to one another, a polymerisable group or cycloalkyl or aryl having up to 20 carbon atoms, which may optionally be monosubstituted or polysubstituted by halogen, preferably F, or by a polymerisable group, x1and x2are each, independently of one another, 0, 1 or 2, y1and y2are each, independently of one another, 0, 1, 2, 3 or 4, B1and B2are each, independently of one another, an aromatic or partially or fully saturated aliphatic six-membered ring in which one or more CH groups may each be replaced by N and one or more non-adjacent CH2groups may each be replaced by O or S, W1and W2are each, independently of one another, -Z1-A1-(Z2-A2)m-R, and one of the two is alternatively R1or A3, but both are not simultaneously H, or U1and U2are each, independently of one another, CH2, O, S, CO or CS, V1and V2are each, independently of one another, (CH2)n, in which from one to four non-adjacent CH2groups may each be replaced by O or S, and one of V1and V2and, in the case where are a n is 1,2 or 3 P24-041 AT Z1and Z2are each, independently of one another, -O-, -S-, -CO-, -COO-, -OCO-, -O- COO-, -CO-NRx-, -NRx-CO-, -O-CH2-, -CH2-O-, -S-CH2-, -CH2-S-, -CF2-O-, -O-CF2-, -CF2-S-, -S-CF2-, -CH2-CH2-, -CF2-CH2-, -CH2-CF2-, -CF2-CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CH-, -CF=CH-, -CH=CF-, -CF=CF-, -C^C-, a combination of two of these groups, where no two O and / or S and / or N atoms are bonded directly to one another, preferably -CH=CH-COO-, or -COO-CH=CH-, or a single bond, Rxdenotes alkyl having 1 to 6 C atoms, A1, A2and A3are each, independently of one another, 1,4-phenylene, in which one or two non-adjacent CH groups may each be replaced by N, 1,4- cyclohexylene, in which one or two non-adjacent CH2groups may each be replaced by O or S, 1,3-dioxolane-4,5-diyl, 1,4-cyclohexenylene, 1,4- bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl, where each of these groups may be monosubstituted or polysubstituted by L, and in addition A1can be a single bond, L is a halogen atom, preferably F, CN, NO2, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkoxycarbonyloxy having 1-7 carbon atoms, in which one or more H atoms may each be replaced by F or Cl, m is in each case, independently, 0, 1, 2 or 3, and R and R1are each, independently of one another, H, F, Cl, Br, I, CN, SCN, SF5, straight-chain or branched alkyl having from 1 or 3 to 25 carbon atoms respectively, which may optionally be monosubstituted or polysubstituted by F, Cl, Br, I or CN, and in which one or more non-adjacent CH2groups may each be replaced by -O-, -S-, -NH-, -NR0-, -CO-, -COO-, -OCO-, -O- COO-, -S-CO-, -CO-S-, -CH=CH- or -C^C-, where no two O and / or S atoms are bonded directly to one another, or a polymerisable group. Particular preference is given to chiral binaphthyl derivatives of the formula A-VI-1 P24-041 AT in which ring B, R0and Z0are as defined for the formulae A-IV and A-V, and b is 0, 1, or 2, in particular those selected from the following formulae A-VI-1a to A-VI-1c: in which ring B, R0,and Z0are as defined for the formula A-VI-1, and as defined for formula A-IV or H or alkyl having from 1 to 4 carbon atoms, and is 0, 1 or 2, and Z0is, in particular, -OC(O)- or a single bond. P24-041 AT The concentration of the one or more chiral dopant(s), in the LC medium is preferably in the range from 0.001 % to 20 %, preferably from 0.05 % to 5 %, more preferably from 0.1 % to 2 %, and, most preferably from 0.5 % to 1.5 %. These preferred concentration ranges apply in particular to the chiral dopant S-4011 or R-4011 (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- 4011 these preferred concentrations have to be decreased, respectively increased proportionally according to the ratio of their HTP values relatively to that of S-4011. The pitch p of the LC media or host mixtures according to the invention is preferably in the range of from 5 to 50 ^m, more preferably from 8 to 30 ^m and particularly preferably from 10 to 20 ^m. Preferably, the media according to the invention comprise a stabiliser selected from the group of compounds of the formulae ST-1 to ST-22. P24-041 AT P24-041 AT P24-041 AT P24-041 AT P24-041 AT in which RSTdenotes H, an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH2groups in these radicals may each be replaced, independently of one another, by -C^C-, -CF2O-, -OCF2-, -CH=CH-, -CO-O-, -O-CO- in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by P24-041 AT ZSTeach, independently of one another, denote -CO-O-, -O-CO-, --CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-CH2O-, P24-041 AT -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C^C- or a single bond, L1and L2each, independently of one another, denote F, Cl, CF3or CHF2, n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7, n2, on each occurrence identically or differently, preferably identically, is an integer from 1 to 12, preferably 2, 3, 4, 5, or 6, very preferably 3, and RSon each occurrence identically or differently, preferably identically, denotes alkyl having 1 to 6 C atoms, preferably n-butyl, p denotes 1 or 2, and q denotes 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. Of the compounds of the formula ST, special preference is given to the compounds of the formulae in which n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 1 or 7 P24-041 AT in which n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3 P24-041 AT In the compounds of the formulae ST-3a and ST-3b, n preferably denotes 3. In the compounds of the formula ST-2a, n preferably denotes 7. Very particularly preferred mixtures according to the invention comprise one or more stabilisers from the group of the compounds of the formulae ST-2a-1, ST-3a-1, ST-3b-1, ST-8-1, ST-9-1 and ST-12: P24-041 AT P24-041 AT The compounds of the formulae ST-1 to ST-12 are preferably each present in the liquid-crystal mixtures according to the invention in amounts of 0.005 – 0.5%, based on the mixture, very preferably in an amount of 100 ppm, 250 ppm, 500 ppm or 1000 ppm. If the mixtures according to the invention comprise two or more compounds from the group of the compounds of the formulae ST-1 to ST-18, the concentration correspondingly increases to 0.01 – 1% in the case of two compounds, based on the mixtures. However, the total proportion of the compounds of the formulae ST-1 to ST-18, based on the mixture according to the invention, should not exceed 2%.  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 medium comprises one or more compounds of formula D in a total concentration of 1 % to 60 %, more preferably 5 % to 45 %, particularly preferably 10% to 30 %. In a preferred embodiment of the present invention, the liquid-crystalline media comprise a compound of formula T, preferably in a total concentration in the range of from 5 % to 35 %, more preferably 6 % to 30 % and particularly preferably 7 % to 25 %, preferably selected from the formulae T-1a, T-2a and T-3a, very preferably selected from T-1a-5, T-2a-2, T-2a-4 and T-3a-2. P24-041 AT In a preferred embodiment, the medium comprises one or more compounds of formula I, preferably of formula I-2 or I-3, in a total concentration in the range of from 1 % to 30 %, more preferably from 2 % to 25 %, very preferably 3% to 20% and particularly preferably from 5 % to 15 %. In a preferred embodiment of the present invention the medium comprises one or more compounds selected from the compounds of the formulae II and GF-1-3 and UI-1-3, preferably of formula II-1 and / or UI-1-3, in a total concentration of 2 % to 25 %, more preferably 3 % to 20 %, particularly preferably 5 % to 15 %. In a preferred embodiment of the present invention the medium comprises one or more compounds of formula IIA-1 in a total concentration of 5 % to 25 %, more preferably 8 % to 20 %, particularly preferably 12 % to 17 %. In a preferred embodiment of the present invention the medium comprises one or more compounds of formula II-1 in an total concentration of 30% or less, more preferably 25% or less, particularly preferably 22% or less. In a preferred embodiment of the present invention the medium comprises one or more compounds selected from the formulae III and IIIa-1 to IIIa-4, preferably III-1 and / or III- 2 and / or IIIa-2 and / or IIIa-3, more preferably III-1f and / or III-1b, and / or III-1h and / or IIIa- 2, in a total concentration of 15 % to 60 % or 65% or 70%, more preferably 20 % to 58 %, particularly preferably 22% to 42% or 25 % to 40 %. In a preferred embodiment of the present invention the medium comprises one or more compounds of formula XII, preferably in a total concentration of 5 % to 30 %, more preferably 8 % to 25 %, particularly preferably 10 % to 20 %. In a preferred embodiment, the medium comprises one or more compounds of the formula D and one or more compounds selected from the group consisting of the formulae I, II and / or IIA, III, XII, T, preferably in a total concentration of 90% or more, more preferably 95%, 96% or 97% or more, very preferably 98% or more and in particular 99% or more. P24-041 AT In a preferred embodiment, the medium comprises one or more compounds of the formula D and one or more compounds selected from the group consisting of the formulae I, II and / or IIA, III, XII, T in a total concentration in the range of from 40% to 90% and a total concentration of 10% or more of one or more compounds of the formula IV. In a preferred embodiment, the medium comprises one or more compounds of the formula D and one or more compounds selected from the group consisting of the formulae I, II and / or IIA, III, XII and T in a total concentration in the range of from 40% to 70% and a total concentration of 30% or more of one or more compounds of the formula IV. In a preferred embodiment, the medium comprises one or more compounds of the formula D and one or more compounds selected from the group consisting of the formulae I, II and / or IIA, III, XII and T in a total concentration in the range of from 40% to 60% and a total concentration of 40% or more of one or more compounds of the formula IV. 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 as described in Tables A and B and given in Table C below and n is 1, 2, 3, 4, 5, 6, or 7: - The medium comprises one or more compounds of formula XII-3, preferably of the formula CPU(F.F)-n-S, preferably in a concentration in the range of from 10 to 30%, in articular from 15% to 25%; - The medium comprises one, two, three, four or more compounds of formula III-1, preferably selected from the compounds of the formulae III-1b, III-1f and III-1h; more preferably of III-1b and III-1h; - The medium comprises a compound of formula III-1b, preferably in a total concentration in the range of from 5% to 40%, more preferably 10% to 35%, in particular 15% to 30%; - The medium comprises a compound of formula III-1h, preferably in a total concentration in the range of from 7% to 35%, more preferably 10% to 30%, in particular 12% to 25%; P24-041 AT - The medium comprises the compound PPU-TO-S and / or PPTU-TO-S and / or PTPU-TO-S and / or PP(1)TO-n-S; - The medium comprises one or more compounds of formula I-2d, preferably the compounds PGU-2-S and / or PGU-3-S and / or PGU-4-S, and / or CPU-2-S and / or CPU-3-S and / or CPU-4-S; - The medium comprises one or more compounds of formula II-1b, preferably the compounds PTU-4-S and / or PTU-5-S; - The medium comprises one or more compounds of formula PPTU-n-S and / or PTPU-n-S in an total concentration in the range of from 15% to 25%; - The medium comprises one or more compounds of formula PPTU-n-S and / or PTPU-n-S and / or PGTU-n-S in a total concentration in the range of from 15 to 30 %, in which n is 1, 2, 3, 4, 5, or 6; - The medium comprises one or more compounds of formula CPTU-n-S in an total concentration in the range of from 10% to 30%, in particular from 14% to 25%; - The medium comprises one or more compounds of formula ST-3, preferably ST-3a and / or ST-3b, particularly preferably ST-3b-1, in a total concentration in the range of from 0.01 to 1%, preferably from 0.05 to 0.5%, particularly from 0.10 to 0.15%. The liquid-crystal media in accordance with the present invention preferably have a clearing point of 90°C or more, more preferably 100°C or more, more preferably 110°C or more, more preferably 120°C or more, more preferably 130°C or more, particularly preferably 140°C or more and very particularly preferably 150°C or more. The nematic phase of the media according to the invention preferably extends at least from 0°C or less to 90°C or more. It is advantageous for the media according to the invention to exhibit even broader nematic phase ranges, preferably at least from -10°C or less to 120°C or more, very preferably at least from -20°C or less to 140°C or more and in particular at least from -30°C or less to 150°C or more, very particularly preferably at least from -40°C or less to 170°C or more. The ^^ of the liquid-crystal medium according to the present invention, at 1 kHz and 20°C, is preferably 5 or more, more preferably 7 or more and very preferably 8 or more. The birefringence (^n) of the liquid-crystal media according to the present invention, at 589 nm (NaD) and 20°C, is preferably 0.280 or more, more preferably 0.300 or more, P24-041 AT even more preferably 0.320 or more, very preferably 0.330 or more and in particular 0.350 or more. The ^n of the liquid-crystal media according to the present invention, at 589 nm (NaD) and 20°C, is preferably in the range from 0.200 to 0.900, more preferably in the range from 0.250 to 0.800, even more preferably in the range from 0.300 to 0.700 and very particularly preferably in the range from 0.350 to 0.600. In a preferred embodiment of the present application, the ^n of the liquid-crystal media in accordance with the present invention is preferably 0.50 or more, more preferably 0.55 or more. The compounds of the formulae I to III in each case include dielectrically positive compounds having a dielectric anisotropy of greater than 3, dielectrically neutral compounds having a dielectric anisotropy of less than 3 and greater than -1.5 and dielectrically negative compounds having a dielectric anisotropy of -1.5 or less. The compounds of the formulae D, I, II and III are preferably dielectrically positive. Preferably, the optical component according to the invention is designed and configured as an optical phase modulator. In a preferred embodiment, the optical component according to the invention is designed and configured for use in a transparent device for phase modulation of IR radiation. In another preferred embodiment, the optical component according to the invention is designed and configured for use in a reflective device for phase modulation of IR radiation. A typical electro-optical modulator comprises conducting, infrared transmitting windows consisting for example of Ge, separated from one another by spacers and having a cell gap in the range of from 1 mm to 5 mm. P24-041 AT According to another aspect of the present invention there is provided a LIDAR scanning system as described in WO2018 / 156643 A1, including a laser configured to emit pulses of light at an operating wavelength in the infrared. The LIDAR scanning system includes a transmit reconfigurable-metasurface configured to reflect an incident pulse of light from the laser as an illumination beam pointing at a selected portion of a field of view, preferably a two dimensional field of view. The pointing of the illumination beam is responsive to a first selected holographic beam steering pattern implemented in the transmit reconfigurable-metasurface. The system further includes a receive reconfigurable-metasurface configured to reflect a return of the illumination beam from the selected portion of the field of view as a relay beam pointing at an optical detector. The pointing of the relay beam is responsive to a second selected holographic beam steering pattern implemented in the receiving reconfigurable metasurface. The system includes an optical detector comprising an array of detector pixels. Each detector pixel includes (i) a photodetector configured to detect light in the return of the illumination beam and (ii) a timing circuit configured to determine a time of flight of the detected light. The optical detector is also configured to output a detection signal indicative of the detected light and a time of flight of the detected light for each pixel of the array. The transmit reconfigurable-metasurface includes a plurality of dynamically adjustable high-Q dielectric resonators arranged on a surface of the reconfigurable-metasurface with inter-element spacing less than the operating wavelength of the laser, where the surface of the reconfigurable-metasurface includes a conducting surface, and the plurality of resonators have a corresponding plurality of adjustable reflection phases providing a dynamically adjustable reflected wave responsive to an incident wave, wherein the conducting surface and the plurality of resonators define a metasurface. Each of the plurality of dielectric resonators includes (i) a pair of regions having high refractive index; and (ii) an electrically-adjustable material disposed in a gap between the regions, wherein the electrically-adjustable material is a liquid crystal material as set forth above and below. According to another aspect of the invention there is provided a reflective spatial light modulator, in particular an LCoS device including the liquid crystal material according to the invention, sandwiched between a transparent glass layer having a transparent electrode, a mirror mounted on a silicon CMOS backplane and PCB. The mirror is divided into a two-dimensional array of individually addressable pixels. Each pixel is individually drivable by a voltage signal to provide a local phase change to at least one P24-041 AT polarization component of an optical signal, thereby providing a two-dimensional array of phase manipulating regions. Pre-alignment of the liquid crystal is provided by alignment layers. Said LCoS device is useful for the integration into optical devices. Preferred devices are a wavelength selective switch (WSS), LIDAR scanner, infrared scene projector, as well as other beam steering applications as shown in the article Micallef, F. (2019). Middle infrared beam-steering using liquid crystals for spatial light modulation (Doctoral thesis). https: / / doi.org / 10.17863 / CAM.39602 (https: / / www.repository.cam.ac.uk / handle / 1810 / 292443). In the present application, the expression dielectrically positive describes compounds or components where ^^ > 3.0, dielectrically neutral describes those where -1.5 ^ ^^ ^ 3.0 and dielectrically negative describes those where ^^ < -1.5. ^^ is determined at a frequency of 1 kHz and at 20°C. The dielectric anisotropy of the respective compound is determined from the results of a solution of 10 % of the respective individual compound in a nematic host mixture. If the solubility of the respective compound in the host mixture is less than 10 %, the concentration is reduced to 5 %. 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 20 µm. The voltage applied is a rectangular wave having a frequency of 1 kHz and an effective value of typically 0.5 V to 1.0 V, but it is always selected to be below the capacitive threshold of the respective test mixture. ^^ is defined as (^^^- ^^), while ^ave.is (^^^+ 2 ^^) / 3. The host mixture used for the determination of physical constants of pure compounds by extrapolation is ZLI-4792 from Merck KGaA, Germany. The absolute values of the dielectric constants, the birefringence (^n) and the rotational viscosity (^1) 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 10 % or in case of insufficient solubility 5 %. The values are extrapolated to a concentration of 100 % of the added compounds. P24-041 AT 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 20°C 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 10 % relative contrast (V10), and the expression saturation voltage refers to the optical saturation and is quoted for 90 % relative contrast (V90), in both cases unless expressly stated otherwise. The capacitive threshold voltage (V0), 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 "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status Nov.1997, Merck KGaA, Germany, and are quoted for a temperature of 20°C, unless expressly stated otherwise. The optical aniso- tropy (^n) is determined at a wavelength of 589.3 nm. The dielectric anisotropy (^^) is determined at a frequency of 1 kHz. 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 ^^ have a cell thickness of approximately 20 µm. The electrode is a circular ITO electrode having an area of 1.13 cm2and a guard ring. The orientation layers are SE-1211 from Nissan Chemicals, Japan, for homeotropic orientation (^^^) and polyimide AL-1054 from Japan Synthetic Rubber, Japan, for homogeneous orientation (^^). The capacitances are determined using a Solatron 1260 frequency response analyser using a sine wave with a voltage of 0.3 Vrms. The light P24-041 AT 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 charac- teristic voltages have been determined under perpendicular observation. The threshold (V10), mid-grey (V50) and saturation (V90) voltages have been determined for 10 %, 50 % and 90 % relative contrast, respectively. The liquid-crystalline media are investigated with respect to their properties in the microwave frequency range as described in A. Penirschke et al. “Cavity Perturbation Method for Characterization of Liquid Crystals up to 35 GHz“, 34thEuropean Microwave Conference – Amsterdam, pp.545-548. Compare in this respect also A. Gaebler et al. “Direct Simulation of Material Permittivities …“, 12MTC 2009 – International Instrumentation and Measurement Technology Conference, Singapore, 2009 (IEEE), pp.463-467, and DE 102004029429 A, 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 0.5mm and an outer diameter of 0.78mm. The effective length is 2.0 cm. The filled capillary is introduced into the centre of the cylindrical cavity with a resonance frequency of 19 GHz. This cavity has a length of 11.5 mm and a radius of 6 mm. The input signal (source) is then applied, and the frequency depending response of the cavity is recorded using a commercial vector network analyser (N5227A PNA Microwave Network Analyzer, Keysight Technologies Inc. USA. For other frequencies, the dimensions of the cavity are adapted correspond- ingly. 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 10 and 11 in the above-mentioned publication A. Penirschke et al., 34thEuropean Microwave Conference – Amsterdam, pp.545-548, 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 P24-041 AT field. To this end, the magnetic field of a permanent magnet is used. The strength of the magnetic field is 0.35 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 crystallisation 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 con- ventional 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.2 g 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 crystallisation. For every material and at each temperature two bottles are stored. If crystallisation 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 1000 h, i.e an LTS value of 1000 h means that the mixture is stable at the given temperature for at least 1000 h. The liquid crystals employed preferably have a positive dielectric anisotropy. This is preferably 2 or more, preferably 4 or more, particularly preferably 6 or more and very particularly preferably 10 or more. Furthermore, the liquid-crystal media according to the invention are characterised by high anisotropy values in the microwave range. The birefringence at about 19 GHz is, P24-041 AT for example, preferably 0.14 or more, particularly preferably 0.15 or more, particularly preferably 0.20 or more, particularly preferably 0.25 or more and very particularly preferably 0.30 or more. In addition, the birefringence is preferably 0.80 or less. The dielectric anisotropy in the microwave range is defined as The tunability (^) is defined as The material quality (^) is defined as , where the maximum dielectric loss is The tunability ^^of the medium according to the invention, measured at 20°C and 19 GHz is 0.250 or more, preferably 0.300 or more, 0.310 or more, 0.320 or more, 0.330 or more, or 0.340 or more, very preferably 0.345 or more and in particular 0.350 or more. The material quality (^) of the preferred liquid-crystal materials is 6 or more, preferably 8 or more, preferably 10 or more, preferably 15 or more, preferably 17 or more, preferably 20 or more, particularly preferably 25 or more and very particularly preferably 30 or more. In the corresponding components, the preferred liquid-crystal materials have phase shifter qualities of 15° / dB or more, preferably 20° / dB or more, preferably 30° / dB or more, preferably 40° / dB or more, preferably 50° / dB or more, particularly preferably 80° / dB or more and very particularly preferably 100° / dB or more. In some embodiments, however, liquid crystals having a negative value of the dielectric anisotropy can also advantageously be used. P24-041 AT 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 0 % to 10 %, preferably 0.1 % to 6 %, based on the mixture as a whole. The concentrations of the individual compounds used are each preferably in the range from 0.1 % to 3 %. The concentration of these and similar additives is not taken into consideration when quoting the values and concen- tration 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 0.05 % to 15 %, more preferably from 1 % to 10 % and most preferably from 2 % to 6 %. 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 0 % to 30 %, more preferably 0.1 % to 20 % and most preferably 1 % to 15 %. The response times are given as rise time (^on) for the time for the change of the relative tuning, respectively of the relative contrast for the electro-optical response, from 0 % to 90 % (t90– t0), i.e. including the delay time (t10– t0), as decay time (^off) for the time for the change of the relative tuning, respectively of the relative contrast for the electro-optical response, from 100 % back to 10 % (t100– t10) and as the total response time (^total= ^on+ ^off), respectively. The liquid-crystal media according to the invention consist of a plurality of compounds, preferably 3 to 30, more preferably 4 to 20 and very preferably 4 to 16 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 P24-041 AT 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 “multibottle” 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 C below. All groups CnH2n+1, CmH2m+1and ClH2l+1, and CnH2n-1, CmH2m-1and ClH2l-1denote straight-chain alkyl or alkylene, respectively, in each case having n, m or l C atoms, wherein n and m, independently are 1, 2, 3, 4, 5, 6 or 7 and l is 1, 2 or 3. Table A lists the codes used for the ring elements of the core structures of the compounds, while Table B shows the linking groups and end groups. Table C shows illustrative structures of compounds with their respective abbreviations. P24-041 AT P24-041 AT P24-041 AT P24-041 AT P24-041 AT E -CH2CH2- Z -CO-O- V -CH=CH- ZI -O-CO- X -CF=CH- O -CH2-O- XI -CH=CF- OI -O-CH2- B -CF=CF- Q -CF2-O- T -C^C- QI -O-CF2- W -CF2CF2- Table B: End groups Left-hand side Right-hand side Used alone CnH2n+1- -n -CnH2n+1 P24-041 AT -nO- CnH2n+1-O- -On -O-CnH2n+1-V- CH2=CH- -V -CH=CH2-nV- CnH2n+1-CH=CH- -nV -CnH2n-CH=CH2-Vn- CH2=CH- CnH2n+1- -Vn -CH=CH-CnH2n+1-nVm- CnH2n+1-CH=CH-CmH2m- -nVm -CnH2n-CH=CH-CmH2m+1-N-N^C--N-C^N-S- S=C=N- -S -N=C=S -F- F- -F -F -CL- Cl- -CL -Cl -M- CFH2- -M -CFH2-D- CF2H- -D -CF2H -T- CF3- -T -CF3-MO- CFH2O- -OM -OCFH2-DO- CF2HO- -OD -OCF2H -TO- CF3O- -OT -OCF3-FXO- CF2=CH-O- -OXF -O-CH=CF2-A-H-C=C--A-C=C-H-nA-CnH2n+1-C^C--An-C=C-CnH2n+1-NA- N=C-C=C- -AN -C=C-C=N -…W…- -CF=CF- -…W… -CF=CF- in which n and m each denote integers, and the three dots “...” are placeholders for other abbreviations from this table. P24-041 AT Branched lateral groups are numbered starting from the position next to the ring (1) where the longest chain is selected, the smaller number indicating the length of the branch and the superscript number in brackets indicates the position of the branch, for 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. Table C: Illustrative structures The following illustrative structures are examples as well as compounds, which are preferably additionally used in the media: InTUI-n-S P24-041 AT -n- P24-041 AT PPG(F)-T-S P24-041 AT PG-n-S P24-041 AT CPG-n-S P24-041 AT P24-041 AT PTP(1,1)-n-S P24-041 AT PPTG(F)-n-S P24-041 AT PTPG(Cl)-n-S P24-041 AT P24-041 AT P24-041 AT P24-041 AT P24-041 AT P24-041 AT P24-041 AT P24-041 AT P24-041 AT CPGU-n-F APGP-n-m in which m and n, identically or differently, are 1, 2, 3, 4, 5, 6 or 7. P24-041 AT 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 stabilisers in the mesogenic media in accordance with the present invention. The total concentration of these and similar compounds in the media is preferably 5 % or less. Table D P24-041 AT P24-041 AT 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. Table E CM 21 P24-041 AT P24-041 AT 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. P24-041 AT Unless indicated otherwise, parts or per cent data denote parts by weight or per cent by weight. Above and below: denotes threshold voltage, capacitive [V] at 20°C, denotes extraordinary refractive index at 20°C and 589 nm, denotes ordinary refractive index at 20°C and 589 nm, denotes optical anisotropy at 20°C and 589 nm, denotes dielectric permittivity perpendicular to the director at 20°C and 1 kHz, denotes dielectric permittivity parallel to the director at 20°C and 1 kHz, denotes dielectric anisotropy at 20°C and 1 kHz, denotes clearing point [°C], denotes rotational viscosity measured at 20°C [mPa^s], denotes elastic constant, "splay" deformation at 20°C [pN], denotes elastic constant, "twist" deformation at 20°C [pN], denotes elastic constant, "bend" deformation at 20°C [pN], denotes average elastic constant defined as Kavg.= + K3) denotes low-temperature stability (nematic phase), determined in test cells or in the bulk, as specified. Unless explicitly noted otherwise, all values indicated in the present application for temperatures, such as, for example, the melting point T(C,N), the transition from the smectic (S) to the nematic (N) phase T(S,N) and the clearing point T(N,I) or clp., are indicated in degrees Celsius (°C). M.p. denotes melting point . Furthermore, Tg = glass state, C = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The numbers between these symbols represent the transition temperatures. The term "threshold voltage" for the present invention relates to the capacitive threshold (V0), also called the Freedericksz threshold, unless explicitly indicated otherwise. In the examples, as is generally usual, the optical threshold can also be indicated for 10 % relative contrast (V10). P24-041 AT The display used for measurement of the capacitive threshold voltage consists of two plane-parallel glass outer plates at a separation of 20 µm, which each have on the insides an electrode layer and an unrubbed polyimide alignment layer on top, which cause a homeotropic edge alignment of the liquid-crystal molecules. The so-called "HTP" denotes the helical twisting power of an optically active or chiral substance in an LC medium (in µm). Unless indicated otherwise, the HTP is measured in the commercially available nematic LC host mixture MLD-6260 (Merck KGaA) at a temperature of 20°C. The Clearing point is measured using the Mettler Thermosystem FP900. The optical anisotropy (^n) is measured using an Abbe Refractometer H005 (Natrium-spectral lamp Na10 at 589nm, 20 °C). The dielectric anisotropy (^^) is measured using an LCR- Meter E4980A / Agilent (G005) at 20°C (^-parallel-cells with JALS 2096-R1). The turn on voltage (V0) is measured using an LCR-Meter E4980A / Agilent (G005) at 20°C (^- parallel-cells with JALS 2096-R1). The rotational viscosity (^1) is measured using a TOYO LCM-2 (0002) at 20°C (gamma 1 negative cells with JALS-2096-R 1 ). The elastic constant (K1, splay) is measured using an LCR-Meter E4980A / Agilent (G005) at 20°C (^ parallel-cells with JALS 2096-R1). K3: The elastic constant (K3, bend) is measured using an LCR-Meter E4980A / Agilent (G005) at 20°C (^-parallel-cells with JALS 2096-R1). Unless explicitly noted otherwise, all concentrations in the present application are indicated in per cent by weight and relate to the corresponding mixture as a whole, comprising all solid or liquid-crystalline components, without solvents. All physical properties are determined in accordance with "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status November 1997, Merck KGaA, Germany, and apply for a temperature of 20°C, unless explicitly indicated otherwise. The present invention is illustrated in detail by the following non-restrictive working examples. P24-041 AT The following abbreviations are used: LDA lithium diisopropylamide MTB ether tert-butyl methyl ether DABCO 1,4-diazabicyclo[2.2.2]octane dist. distilled THF tetrahydrofuran XPhos 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenylXPhos Pd G2 chloro(2 dicyclohexylphosphino 2′,4′,6′ triisopropyl 1,1′biphenyl)[2 (2′ amino 1,1′ biphenyl)palladium (II)Synthesis Example 16-((3,5-Difluoro-4-isothiocyanatophenyl)ethynyl)-2-propyl-1H- indene Step 1.1: 5-Bromo-2-propyl-2,3-dihydro-1H-inden-1-one Anhydrous THF (1.7 L) is cooled down to -40°C, and lithium diisopropylamide (LDA, 2 M solution in THF / heptane / ethylbenzene, 0.60 mol, 300 ml) is charged under nitrogen atmosphere. The solution is cooled down to -70°C.5-Bromo-dihydroindenone (CAS 34598-49-7, 115 g, 0.54 mol) is charged to a separate reaction flask under nitrogen atmosphere. Anhydrous THF (1.15 l) is added, and the mixture stirred. When full dissolution is observed, the orange solution is transferred to the LDA / THF solution in the other flask under inert atmosphere. The addition rate is adjusted to keep the reaction temperature below -65°C. At the end of addition, the dark brown solution is left to warm up to 0°C and iodopropane (64 ml, 0.65 mol) is added quickly. The resulting reaction mixture is left stirring overnight, warming up slowly to room temperature. After 18 hours, distilled water (1 l) is added to the reaction mixture at room temperature. The aqueous layer is decanted and retained. The organic layer is concentrated in vacuo to ca.1 l thick mixture. The aqueous layer is extracted twice with ethyl acetate, and the ethyl acetate layer combined with the THF thick mixture above. Once combined, the organic layer is washed with brine, dried over magnesium sulphate, and filtered off. Removal of the solvent gives a reddish oily residue. This is triturated with heptane and the solid obtained removed by filtration and rinsed with heptane. The heptane filtrates are evaporated to dryness to give a brown oil. Further purification via silica gel P24-041 AT chromatography (eluent heptane, gradually increasing the polarity to heptane / 2% ethyl acetate). Removal of the solvent from the recovered fractions gives 5-bromo-2-propyl- 2,3-dihydro-1H-inden-1-one as an orange oil. 5-Bromo-2-propyl-2,3-dihydro-1H-inden-1-ol 5-Bromo-2-propyl-2,3-dihydro-1H-inden-1-one (17.7 g, 69.9 mmol) is charged to a reaction flask under nitrogen atmosphere. THF (600 ml) is added, and a yellow solution is obtained. Methanol (300 ml) is added and the solution stirred under nitrogen atmosphere for 20 minutes at room temperature. Sodium borohydride (4 g, 105 mmol) is added portion-wise. The reaction mixture is left stirring at room temperature overnight. The reaction mixture is cooled to 4°C and 2 N HCl (100 ml) is added dropwise. The cloudy pale-yellow mixture is then stirred and left to warm up to room temperature. MTBE (560 ml) and distilled water (300 ml) are added to achieve a good phase separation. The layers are decanted, and the aqueous layer is extracted with further MTBE. All organics are combined, washed with distilled water and brine and dried over magnesium sulphate. After filtration, the filtrates are concentrated to dryness to give 5-bromo-2-propyl-2,3-dihydro-1H-inden-1-ol as a light brown oil. The material is used directly in the next stage without further purification. 5-Bromo-2-propyl-2,3-dihydro-1H-inden-1-ol (17.3 g, 67.8 mmol) is dissolved in dichloromethane (200 ml) under nitrogen atmosphere. p-Toluene sulfonic acid (0.13 g, 0.67 mmol) is added to the reaction mixture and it is heated to reflux overnight. The reaction is then left to cool down before dilution with dichloromethane. The reaction mixture is washed 3 times with 10% NaHCO3then with brine. The organic layer is dried over magnesium sulphate and filtered off. The filtrates are evaporated to dryness to give a pale brown oil. The oil is purified by filtering through silica (eluent heptane).6- Bromo-2-propyl-1H-indene is obtained as a colourless oil. Step 1.4: 2,6-Difluoro-4-((2-propyl-1H-inden-6-yl)ethynyl)aniline P24-041 AT A solution of 6-bromo-2-propyl-1H-indene (2.3 g, 8.0 mmol) and 4-ethynyl-2,6- difluoroaniline (CAS 753501-37-0) (1.5 g, 9.8 mmol) in THF (20 ml) and diisopropylamine (20 ml) is treated with XPhos (10 mg, 0.02 mmol), XPhos Pd G2 (15 mg, 0.02 mmol) and copper(I) iodide (2 mg, 0.01 mmol) at 50°C under Argon atmosphere, and the reaction mixture is stirred at reflux temperature overnight. It is then allowed to cool down to room temperature, filtered, washed with THF and concentrated in vacuo. The residue is purified by flash chromatography (silica gel, eluent 1-chlorobutane) to give 2,6-difluoro-4-((2-propyl-1H-inden-6-yl)ethynyl)aniline as a yellow oil. Step 1.5: 6-((3,5-Difluoro-4-isothiocyanatophenyl)ethynyl)-2-propyl-1H-indene Thiophosgene (0.5 ml, 6.3 mmol) is slowly added to a solution of 2,6-difluoro-4-((2- propyl-1H-inden-6-yl)ethynyl)aniline (1.6 g, 4.6 mmol) and DABCO (1.3 g, 11.6 mmol) in dichloromethane (25 ml) at 0°C under argon atmosphere, and the reaction mixture is stirred at room temperature overnight. Then it is quenched with dist. water, filtered over silica gel, washed with dichloromethane and concentrated in vacuo. The residue is purified by flash chromatography (silica gel, eluent heptane) and subsequent crystallization (heptane) to give light yellow crystals of 6-((3,5-difluoro-4- isothiocyanatophenyl)ethynyl)-2-propyl-1H-indene. Phase sequence: K 73 N (50) I. ^n = 0.4182 ^^^= 20.4^ In analogy to Synthesis Example 1 the following compounds are obtained: P24-041 AT P24-041 AT P24-041 AT P24-041 AT 5 10 15 20 25 30 P24-041 AT P24-041 AT P24-041 AT P24-041 AT P24-041 AT 5 10 15 20 25 30 P24-041 AT P24-041 AT Mixture Examples Host mixture H1 has the following composition: PTU-3-S 15.98 % PGU-3-S 13.98 % PPTU-5-S 19.98 % CPU-2-S 34.96 % CPU-4-S 14.98 % ST-3b-1 0.12 % ^100.0 %The following comparative Example C1 and Example Mixture M1 and are prepared from host mixture H1 as indicated in the following tables. P24-041 AT The replacement of the compound PTU-5-S of Comparative Example C1 with the compound InTU-3-S according to the invention results in an improvement of the clearing temperature, the tunability, the dielectric loss and of the figure-of-merit. P24-041 AT PPU-TO-S 23.0 CPTU-5-S 11.0 InTU-3-S 20.0 InTUI-5-S 12.0 InP(2)TU-5-S 10.0 100.0

Claims

P24-041 AT Patent Claims 1. A compound of formula Din which RDdenotes H, straight-chain alkyl having 1 to 12 C atoms or branched alkyl having 3 to 12 C atom, or straight-chain alkenyl having 2 to 12 C atoms, or branched alkenyl having 3 to 12 C atoms, or straight-chain alkynyl having 2 to 12 C atoms or branched alkynyl having 4 to 12 C atoms, in which one or more CH2-groupsadjacent CH2-groups may be replaced by O, or denotes a group RP, RPdenotes halogen, -CN, -NCS, RF-, RF-O- or RF-S-, wherein RFdenotes fluorinated alkyl having 1 to 9 C atoms, ZD1, ZD2, ZD3and ZD4, identically or differently, denote -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -N=N-, -C=N-N=C-, -CH=N-, -N=CH-, -C^C-, -C^C-C^C-, or a single bond, where ZD1alternatively denotes -O-, -S-, -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)3-, -(CH2)4-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH=CH-CH2O-, -CH=CH-CO-O-, -OCH2-CH=CH-, or -O-CO-CH=CH-, XDdenotes -C^C-CN, -NCS, or -C^C-NCS,, identically or differently, denote a radical selected from the following groups: a) the group consisting of 1,4-phenylene, 1,4-naphthylene, and 2,6-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-1,4-cyclohexylene, 1,4-cyclohexenylene, tetralin- 2,6-diyl, tetralin-5,8-diyl, decalin-2,6-diyl, bicyclo[1.1.1]pentane-1,3-diyl, 4,4´- bicyclohexylene, bicyclo[2.2.2]octane-1,4-diyl, and spiro[3.3]heptane-2,6-diyl, in which one or two CH groups may be replaced by N, one or more non-adjacentP24-041 AT CH2groups may be replaced by -O- and / or -S- and in which one or more H atoms may be replaced by L, c) the group consisting of thiophene-2,5-diyl, thieno[3,2-b]thiophene-2,5-diyl, and selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L,L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF5or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy each having 1 to 12 C atoms, or cycloalkyl having 3 to 5 C atoms, t1, t2, t3 and t4, identically or differently, are 0,1 or 2, where t1 + t2 + t3 + t4 is 1, 2 or 3.

2. The compound according to claim 1, wherein the compound is selected from the compounds of the formulae D-1 and D-2in which RD,ZD4 and XD have the meanings given inclaim 1, and t2 is 0, 1 or 2, t4 is 0 or 1, and t2+t4 is 1, 2 or 3.

3. The compound according to claim 2, wherein ZD2and ZD4, identically or differently, denote -CH=CH-, -CF=CF-, -C^C-, or a single bond.

4. The compound according to one or more of claims 1 to 3, whereinP24-041 ATin which RL, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, or cycloalkyl having 3 to 5 C atoms, wherein which W denotes N, C-H, C-F or C-Cl, and Y1and Y2, identically or differently, denote H, Cl, F, methyl or ethyl.

5. The compound according to one or more of claims 1 to 4, wherein XDdenotes -NCS.

6. A liquid crystal medium comprising one or more compounds of formula D according to one or more of claims 1 to 5.

7. The liquid crystal medium according to claim 6, wherein the medium additionally comprises one or more compounds selected from the group of compounds of the formulae I, II and III: IIIP24-041 ATIII in which R1denotes H, non-fluorinated alkyl having 1 to 12 C atoms, or non- fluorinated alkenyl having 2 to 12 C atoms, in which one or more CH2- groups may be replaced, where one or more non-adjacent CH2-groups may be replaced by O,on each occurrence, independently of one another,in which RL, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms,or denotewhich one or more H atoms may bereplaced by alkyl having 1 to 6 C atoms or F,P24-041 ATin which RL, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms, and whereinR2denotes H, non-fluorinated alkyl having 1 to 12 C atoms, or non-fluorinated alkenyl having 2 to 12 C atoms, in which one or more CH2-groups may be replacedwhere one or more non-adjacent CH2-groups may be replaced by O, Z21denotes trans-CH=CH-, trans-CF=CF- or -C≡C-, andP24-041 ATRL, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms,more H atoms may be replaced by alkyl having 1 to 6 C atoms or F,occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms; R3denotes H, non-fluorinated alkyl or non-fluorinated alkoxy having 1 to 17 C atoms, or non-fluorinated alkenyl, non-fluorinated alkenyloxy or non-fluorinated alkoxyalkyl having 2 to 15 C atoms, in which one or more CH2-groups may be replacedP24-041 AT one of Z31and Z32denotes trans-CH=CH-, trans-CF=CF- or -C≡C- and the other one, independently thereof, denotes -C≡C-, trans-CH=CH-, trans- CF=CF- or a single bond, andwhich RL, on each occurrence, identically or differently, denotes H or alkyl having 1 to 6 C atoms,in which one or more H atoms may be replaced by alkyl having 1 to 6 C atoms or F, and whereinalternatively denotesP24-041 ATidentically or differently, denotes H or alkyl having 1 to 6 C atoms.

8. The liquid crystal medium according to claim 6 or 7, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae I-1 to I-5in which L1, L2and L3on each occurrence, identically or differently, denote H or F, andP24-041 AThave the meanings given for formula I in claim 7.

9. The liquid crystal medium according to one or more of claims 6 to 8, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae II-1 to II-3in whichhave the meanings given in claim 7 for formula II.

10. The liquid crystal medium according to one or more of claims 6 to 9, wherein the medium comprises one or more compounds of formula III selected from the compounds of the formulae III-1 to III-6P24-041 ATin which Z31and Z32independently of one another denote trans-CH=CH- or trans- CF=CF-, and in formula III-6 alternatively one of Z31and Z32may denote -C≡C-, R3denotes non-fluorinated alkyl or alkoxy having 1 to 7 C atoms or non-fluorinated alkenyl having 2 to 7 C atoms, and one ofand the others, independently of one another, denoteP24-041 AT where .

11. The medium according to one or more of claims 6 to 10, wherein the medium comprises one or more compounds selected from the formulae IIIa-1, IIIa-2, IIIa-3 and IIIa-4:in which R3has the meanings defined for formula III in claim 7.

12. The liquid crystal medium according to one or more of claims 6 to 11, wherein the medium comprises one or more compounds of formula UIin whichP24-041 AT RUdenotes H, straight-chain or branched non-fluorinated alkyl having 1 to 12 C atoms or non-fluorinated alkenyl having 2 to 12 C atoms, in which one or more CH2-groups may be replacedwhere one or more non-adjacent CH2-groups may be replaced by O, or denotes a group RP, RPdenotes halogen, CN, NCS, fluorinated alkyl, RF-O- or RF-S-, wherein RFdenotes fluorinated alkyl or fluorinated alkenyl having up to 9 C atoms, ZU1denotes -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C^C- or -C^C-C^C-, XU1, XU2, identically or differently, denote Cl or F,denote a radical selected from the following groups: a) the group consisting of 1,4-phenylene, 1,4-naphthylene, and 2,6-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-1,4-cyclohexylene, 1,4-cyclohexenylene, tetralin- 2,6-diyl, tetralin-5,8-diyl, decalin-2,6-diyl, bicyclo[1.1.1]pentane-1,3-diyl, 4,4´- bicyclohexylene, bicyclo[2.2.2]octane-1,4-diyl, and spiro[3.3]heptane-2,6-diyl, in which one or two CH groups may be replaced by N, one or more non-adjacent CH2groups may be replaced by -O- and / or -S- and in which one or more H atoms may be replaced by L, c) the group consisting of thiophene-2,5-diyl, thieno[3,2-b]thiophene-2,5-diyl, selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF5or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy each having 1 to 12 C atoms, u is 0 or 1, v is 0 or 1, where the compounds of the formula UI are excluded from the compounds of the formulae I, II and III of claim 7.P24-041 AT 13. An electronic component comprising a first substrate and a second substrate facing each other, a liquid crystal layer sandwiched between said substrates, an electrode provided on each substrate or two electrodes provided on only one of the substrates for supplying an electric potential across said liquid crystal layer to drive liquid crystals in a predetermined configuration, characterised in that the liquid crystal layer comprises the liquid crystal medium according to one or more of claims 6 to 12.

14. The component according to claim 13, wherein the component is configured for use in high-frequency technology.

15. The component according to claim 14, wherein the component is a liquid-crystal based antenna element, a phase shifter, a tunable filter, a tunable metamaterial structure, a matching network or a varactor.

16. A microwave antenna array, characterised in that it comprises one or more components according to claim 14 or 15.

17. The component according to claim 13, wherein the component is a transmissive or a reflective spatial light modulator.

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