Dichroic dye compositions

Abstract

The present invention relates to compositions comprising a combination of benzothiadiazole and thiadiazoquinoxaline derivatives, to liquid-crystalline media containing such compositions and to the use of such compositions and such media in optical, electronic and electro-optical devices, in particular for devices for regulating the transfer of energy from an external space into an internal space, for example in switchable windows.

Description

[0001] The present invention relates to compositions comprising a combination of benzothiadiazole and thiadiazoquinoxaline derivatives, to liquid-crystalline media containing such compositions and to the use of such compositions and such media in optical, electronic and electro-optical devices, in particular for devices for regulating the transfer of energy from an external space into an internal space, for example in switchable windows.

[0002] Liquid crystals are used in particular as dielectrics in display devices, where the optical properties of such materials can be influenced by an applied voltage. Electro-optical devices based on liquid crystals are well known in the art and can be based on various effects. Devices of this type are, for example, cells with dynamic scattering, DAP (alignment phase deformation) cells, TN cells with twisted nematic structures, STN ("super twisted nematic") cells, SBE ("super birefringence effect") cells, OMI ("optical mode interference") cells, and guest-host cells.

[0003] Devices based on the guest-host effect were first described by Heilmeier and Zanoni (GH Heilmeier et al., Appl. Phys. Lett., 1968, 13, 91f.) and have since found widespread use, primarily in liquid crystal (LC) display elements. In a guest-host system, the LC medium contains one or more dichroic dyes in addition to the liquid crystal. Due to the directional dependence of the absorption by the dye molecules, the transmittance of the dye-doped liquid crystal for light can be modulated when the dye changes its alignment together with the liquid crystal.

[0004] Besides use in LC displays, devices of this type are also used as switching elements for regulating the transfer of light or energy, as described, for example, in WO 2009 / 141295 and WO 2010 / 118422.

[0005] For devices regulating the transfer of energy from the external space into the internal space, different technical solutions have been proposed.

[0006] In one of the possible modes for use in devices, a liquid crystal medium in combination with one or more dichroic dyes as generally described above can be used in the switching layers. By applying a voltage, a change in the directional alignment of the dichroic dye molecules can be achieved in these switching layers. Due to the direction-dependent absorption, a change in the transmittance of the switching layer can be obtained. Corresponding devices are described, for example, in WO 2009 / 141295.

[0007] Alternatively, this change in the transmission behavior can also be achieved in the absence of voltage by a temperature-induced conversion of the isotropic state of the liquid-crystalline medium into the liquid-crystalline state, as described, for example, in US 2010 / 0259698.

[0008] WO 2009 / 141295 and WO 2010 / 118422 describe liquid crystal media for guest-host display elements, comprising cyanobiphenyl derivatives and one or more dichroic dyes. For the same application, US 6033598 and US 5762824 describe LC media, which, in addition to one or more dichroic dyes, comprise one or more compounds, each of which consists of three ring elements substituted by one or more fluorine atoms.

[0009] The use of rylene dyes in such devices has been described, for example, in WO 2009 / 141295, WO 2013 / 004677 and WO 2014 / 090373.

[0010] WO 2014 / 187529 describes the use of liquid-crystalline media comprising benzothiadiazole derivatives for use in devices for regulating the transfer of energy from an external space into an internal space.

[0011] WO 2016 / 177449 ​​describes the use of liquid-crystalline media comprising thiadiazoquinoxaline derivatives for use in devices for regulating the transfer of energy from an external space into an internal space.

[0012] There remains a need in the art for dichroic dye compounds and compositions and media comprising these compounds that yield benefits with respect to device performance and reliability.

[0013] Therefore, the object of the present invention is to provide improved compositions comprising dichroic compounds, wherein these compositions are particularly suitable for guest-host applications. A specific object is to provide compositions that can provide benefits in terms of performance, appearance, stability and reliability, and when used under more demanding working conditions such as at high temperatures or under direct and long-term sunlight exposure. Another object is to provide improved liquid crystal media, which include these compositions and which exhibit a broad and stable LC phase range and particularly advantageous low-temperature stability and which can additionally produce suitable high order. Another object is to provide a stable and reliable switching medium for electro-optical applications, which allows for devices for regulating the transfer of energy from an external space into an internal space, especially in smart switchable windows, to obtain specific beneficial properties, for example, in terms of stability or aesthetic impressions with respect to direct and long-term sunlight exposure. Other objects of the present invention are immediately apparent to those skilled in the art from the following specific embodiments.

[0014] This object is solved by the subject matter defined in the independent claims, while preferred embodiments are set forth in the respective dependent claims and are further described in the following.

[0015] The present invention provides, inter alia, the following items, including main aspects, preferred embodiments and specific features, which individually and in combination contribute to solving the above objects and ultimately provide additional advantages.

[0016] A first aspect of the present invention provides a composition comprising

[0017] At least one compound of formula I

[0018]

[0019] and at least one compound of formula II

[0020]

[0021] in

[0022] R 1 In each occurrence, H, F, CN, N(R z )2、Si(R z )3 or a straight-chain or branched alkyl or alkoxy radical having 1 to 20 C atoms, wherein, in addition, one or more non-adjacent CH2 groups can each independently of one another be connected via -C(R) in such a way that the O and / or S atoms are not directly connected to one another z )=C(R z )-、-C≡C-、 -N(R z )-, -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- and wherein, in addition, one or more H atoms may be replaced by F or CN,

[0023] X represents CR in the same or different way each time it appears a or N,

[0024] R a represents, identically or differently on each occurrence, straight-chain or branched alkyl having 1 to 12 C atoms, F, Cl, N(R z )2 or CN,

[0025] R 2 and R z represents, identically or differently on each occurrence, H, halogen, straight-chain, branched or cyclic alkyl having 1 to 12 C atoms, wherein, in addition, one or more non-adjacent CH2 groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that the O and / or S atoms are not directly connected to one another, and wherein in addition, one or more H atoms may be replaced by F or Cl,

[0026] Ar1 and Ar 2 represents, identically or differently on each occurrence, aryl or heteroaryl, which may be substituted by one or more radicals L,

[0027] L, in each occurrence, represents, identically or differently, F, Cl, CN, OH, SCN, SF5, N(R z )2 or in each case optionally fluorinated, straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms,

[0028] Z 1 represents a single bond, -O-, -S-, -C(O)-, -CR- y1 R y2 -, -CF2O-, -OCF2-, -C(O)-O-, -OC(O)-, -OCH2-, -CH2O-, -CR x1 =CR x2 -、-C≡C-、-CR x1 =CR x2 -CO-, -CO-CR x1 =CR x2 -、-CR x1 =CR x2 -COO-, -OCO-CR x1 =CR x2 -or-N=N-,

[0029] Z 2 represents, identically or differently on each occurrence, a single bond, -CF2O-, -OCF2- or -C≡C-,

[0030] a, b, c and d are independently 0 or 1,

[0031] R x1 , R x2 independently of one another represent H, F, Cl, CN or an alkyl radical having 1 to 12 C atoms,

[0032] R y1 represents H or an alkyl group having 1 to 12 C atoms, and

[0033] R y2 represents an alkyl group having 1 to 12 C atoms.

[0034] It has been found that, surprisingly, the compositions according to the invention comprising at least one compound of the formula I as described above and below in combination with at least one compound of the formula II as described above and below exhibit very good combined properties and characteristics, for example with regard to enhanced light and temperature stability and improved solubility in liquid-crystalline media.

[0035] While compounds of Formula I by themselves, as well as compounds of Formula II by themselves, may already exhibit favorable properties, such as higher dichroic ratios, favorable color purity, and large extinction coefficients, especially in the VIS and / or NIR regions of light, using the two classes of compounds together may provide other unexpected benefits.

[0036] The composition according to the invention containing a combination of compounds of formula I and formula II can provide improved light resistance and enhanced solubility in liquid crystal media. In this regard, the composition can also exhibit excellent stability even under long-term light irradiation at high temperatures (e.g., temperatures up to 70° C. and above).

[0037] The improved solubility of the compounds and the entire composition advantageously contributes to the improved ability to provide tailor-made doped dyed liquid crystal media, especially in providing specific colors or even covering the entire VIS range to obtain a black or neutral appearance. Surprisingly, the NIR spectral range can also be at least partially covered.

[0038] The composition comprising the combination of compounds together may provide minimal or even undiscernible residual fluorescence, especially in the visible spectrum, so that unwanted or undesirable color artefacts such as red glow may be avoided or at least significantly reduced.

[0039] These favorable combined properties and characteristics of the compositions can in turn be beneficial in terms of device stability, reliability, performance, and appearance, even under more demanding environmental or operating conditions, such as in terms of temperature or light exposure, such as in devices for optical, electro-optical, and electronic applications.

[0040] The compositions according to the invention are particularly suitable for guest-host applications, such as in dimmable smart windows, in which dye-doped liquid-crystalline media can exhibit a suitably broad and stable LC phase range and particularly advantageous low-temperature stability.

[0041] Preferably, the composition comprises two or more compounds of formula I and two or more compounds of formula II.

[0042] A further aspect of the present invention therefore relates to a liquid-crystalline medium comprising a composition according to the invention and further one or more mesogenic compounds.

[0043] The liquid-crystalline media according to the invention may therefore offer benefits with regard to device performance and reliability, in particular in smart switchable windows, for example with regard to stability with respect to direct and long-term sunlight exposure or with regard to the aesthetic impression.

[0044] A further aspect of the present invention therefore relates to the use of a liquid-crystalline medium according to the invention in an architectural window or a vehicle sunroof.

[0045] The device according to the invention may also be used in commercial vehicles, ships, trains or aircraft.

[0046] In another aspect according to the invention, a device for regulating the transfer of energy from an external space into an internal space is provided, wherein the device contains a switching layer comprising a liquid crystal medium according to the invention. In particular, the device can be included in a window, especially a window of a building or a facade.

[0047] Therefore, another aspect of the invention relates to a window comprising the device for regulating the transfer of energy from an external space into an internal space as described herein.

[0048] In a further aspect of the invention, the compositions according to the invention are used in electro-optical displays, devices for regulating the transfer of energy from an external space into an internal space, electrical semiconductors, organic field effect transistors, printed circuits, radio frequency identification components, diodes, organic light-emitting diodes, light-emitting components, photovoltaic devices (especially as sensitizers or semiconductors therein), optical sensors, effect pigments, decorative elements or as dyes for coloring polymers, for example in the automotive sector.

[0049] The present invention is illustrated below by describing in detail aspects, embodiments and specific features without thereby limiting the invention, and specific embodiments are described in more detail.

[0050] In the present invention, a device for regulating the transfer of energy from an exterior space into an interior space preferably means a device that regulates the transfer of energy, in particular light and especially daylight, through an area arranged in a structure with relatively low energy transmittance. The structure with low energy transmittance may, for example, be a wall or a vehicle body. Thus, the energy may, for example, pass through an open area or, in particular, a glass area in a wall. Thus, the device is preferably arranged as a window, for example as a constituent of an insulated glazing unit.

[0051] A conditioned transfer of energy is performed from an exterior space of an environment, preferably exposed to direct or indirect solar radiation, into an interior space of, for example, a building or a vehicle or another unit that is substantially isolated from the environment.

[0052] For the purposes of the present invention, the term energy means electromagnetic radiation energy in UV-A, VIS and NIR regions. In particular, it means radiant energy that is not absorbed by the material (e.g., glass) commonly used in windows or is only absorbed to a negligible degree. Herein, the UV-A region means a wavelength range of 320 to 380 nm, the VIS region means a wavelength range of 380 nm to 780 nm, and the NIR region means a wavelength range of 780 nm to 2000 nm. Correspondingly, the term light generally means electromagnetic radiation with a wavelength between 320 and 2000 nm, and particularly between 380 nm to 780 nm.

[0053] As used herein, dichroic dyes refer to light absorbing compounds in which the absorption characteristics depend on the orientation of the compound relative to the direction of light polarization. The dichroic dye compounds of the present invention generally have an elongated shape, i.e. the compound is significantly longer in one spatial direction (i.e. along the longitudinal axis) than in the other two spatial directions.

[0054] The term "organic group" means a carbon or hydrocarbon group.

[0055] The term "carbonyl" refers to a monovalent or multivalent organic group containing at least one carbon atom, wherein the group contains no other atoms (e.g., -C≡C-) or optionally contains one or more other atoms (e.g., N, O, S, P, Si, Se, As, Te or Ge) (e.g., carbonyl, etc.). The term "hydrocarbyl" refers to a carbon group that additionally contains one or more H atoms and optionally contains one or more heteroatoms (e.g., N, O, S, P, Si, Se, As, Te or Ge).

[0056] "Halogen" means F, Cl, Br or I, preferably F or Cl.

[0057] The carbyl or hydrocarbyl group may be a saturated group or an unsaturated group. An unsaturated group is, for example, an aryl, an alkenyl or an alkynyl group. The carbyl or hydrocarbyl group having 3 or more atoms may be straight chain, branched and / or cyclic and may also contain spiro linkages or condensed rings.

[0058] The terms "alkyl," "aryl," "heteroaryl," and the like also encompass multivalent groups such as alkylene, arylene, heteroarylene, and the like.

[0059] The term "aryl" refers to an aromatic carbon group or a group derived therefrom. The term "heteroaryl" refers to an "aryl" as defined above containing one or more heteroatoms.

[0060] Preferred carbyl and hydrocarbyl groups are optionally substituted alkyl, alkenyl, alkynyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy groups having 1 to 40, preferably 1 to 25 and particularly preferably 1 to 18 C atoms; optionally substituted aryl or aryloxy groups having 6 to 40, preferably 6 to 25 C atoms; or optionally substituted alkylaryl, arylalkyl, alkylaryloxy, arylalkyloxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy and aryloxycarbonyloxy groups having 6 to 40, preferably 6 to 25 C atoms.

[0061] Other preferred carbon and hydrocarbon groups are C1-C 40 Alkyl, C2-C 40 Alkenyl, C2-C 40 Alkynyl, C3-C 40 Allyl, C4-C 40 Alkyldiene, C4-C 40 Polyene, C6-C 40 Aryl, C6-C 40 Alkyl aryl, C6-C 40 Arylalkyl, C6-C 40 Alkyl aryloxy, C6-C 40 Arylalkyloxy, C2-C 40 Heteroaryl, C4-C 40 Cycloalkyl, C4-C 40 Particularly preferred are C1-C 22 Alkyl, C2-C 22 Alkenyl, C2-C 22 Alkynyl, C3-C 22 Allyl, C4-C 22 Alkyldiene, C6-C 12 Aryl, C6-C 20 Arylalkyl and C2-C 20 Heteroaryl.

[0062] Other preferred carbon and hydrocarbon radicals are straight-chain, branched or cyclic alkyl radicals having 1 to 40, preferably 1 to 25, C atoms, which are unsubstituted or mono- or polysubstituted by F, Cl, Br, I or CN, and in which one or more non-adjacent CH2 groups can each be independently substituted by -C(R) in such a way that the O and / or S atoms are not directly connected to one another. b )=C(R b )-、-C≡C-、-N(R b )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- substitution.

[0063] R bPreferably it denotes H, halogen, a straight-chain, branched or cyclic alkyl chain having 1 to 25 C atoms, in which one or more non-adjacent C atoms may furthermore be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- and in which one or more H atoms may be replaced by fluorine, optionally substituted aryl or aryloxy having 6 to 40 C atoms or optionally substituted heteroaryl or heteroaryloxy having 2 to 40 C atoms.

[0064] Preferred alkyl groups are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 2-methylbutyl, n-pentyl, sec-pentyl, cyclopentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, trifluoromethyl, perfluoro-n-butyl, 2,2,2-trifluoroethyl, perfluorooctyl and perfluorohexyl.

[0065] Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl and cyclooctenyl.

[0066] Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl and octynyl.

[0067] Preferred alkoxy groups are, for example, methoxy, ethoxy, 2-methoxyethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, 2-methylbutoxy, n-pentoxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, n-undecyloxy and n-dodecyloxy.

[0068] Preferred amino groups are, for example, dimethylamino, methylamino, methylphenylamino and phenylamino.

[0069] Aryl and heteroaryl groups may be monocyclic or polycyclic, i.e. they may contain one ring (e.g. phenyl) or two or more rings, which may also be fused (e.g. naphthyl) or covalently bonded (e.g. biphenyl), or comprise a combination of fused and linked rings. Heteroaryl groups contain one or more heteroatoms, preferably selected from O, N, S and Se. Ring systems of this type may also contain independent non-conjugated units, as is the case, for example, in the fluorene basic structure.

[0070] Particularly preferred are mono-, bi- or tricyclic aryl radicals having 6 to 25 C atoms and mono-, bi- or tricyclic heteroaryl radicals having 2 to 25 C atoms, which optionally contain fused rings and are optionally substituted. Further preferred are 5-, 6- or 7-membered aryl and heteroaryl radicals, in which, in addition, one or more CH groups may be replaced by N, S or O in such a way that the O atoms and / or S atoms are not directly connected to one another.

[0071] Preferred aryl groups are derived from, for example, the following parent structures: benzene, biphenyl, terphenyl, [1,1':3',1"]terphenyl, naphthalene, anthracene, binaphthyl, phenanthrene, pyrene, dihydropyrene, chrysene, perylene, tetracene, pentacene, benzopyrene, fluorene, indene, indenofluorene, spirobifluorene, and the like.

[0072] Preferred heteroaryl groups are, for example, 5-membered rings such as pyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole, furan, thiophene, selenophene, oxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-oxadiazole, 4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, a 6-membered ring such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine or a fused group such as indole, isoindole, indolizine, indazole, benzimidazole, benzoimidazole, triazole, purine, naphthimidazole, phenanthimidazole, pyridimidazole, pyrazimidazole, quinoxalinimidazole, benzoxazole, naphthimidazole, anthraxidazole, phenanthimidazole, isoxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, benzisoquinoline, acridine, phenothiazine The heteroaryl group may also be substituted by an alkyl, alkoxy, sulfanyl, fluorine, fluorine, or other aryl or heteroaryl group.

[0073] (Non-aromatic) alicyclic and heterocyclic groups include both saturated rings, i.e. rings containing only single bonds, and partially unsaturated rings, i.e. those which may also contain multiple bonds. The heterocyclic ring contains one or more heteroatoms, preferably selected from Si, O, N, S and Se.

[0074] (Non-aromatic) alicyclic groups and heterocyclic groups can be monocyclic, i.e. contain only one ring (e.g. cyclohexane), or polycyclic, i.e. contain multiple rings (e.g. decalin or bicyclooctane). Saturated groups are particularly preferred. In addition, mono-, bi- or tricyclic groups with 3-25 C atoms are preferred, which optionally contain fused rings and are optionally substituted. Further preferred are 5-, 6-, 7- or 8-membered carbocyclic groups, wherein in addition, one or more C atoms may be substituted by Si and / or one or more CH groups may be substituted by N and / or one or more non-adjacent CH2 groups may be substituted by-O- and / or-S-.

[0075] Preferred alicyclic and heterocyclic groups are, for example, 5-membered groups, such as cyclopentane, tetrahydrofuran, tetrahydrothiophene, pyrrolidine; 6-membered groups, such as cyclohexane, silinane, cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dioxane, 1,3-dithiane, piperidine; 7-membered groups, such as cycloheptane; and condensed groups, such as tetralin, decalin, indane, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, octahydro-4,7-methanoindan-2,5-diyl.

[0076] The aryl, heteroaryl, carbonyl and hydrocarbon groups optionally have one or more substituents, which are preferably selected from the group comprising silyl, sulfonic acid, sulfonyl, formyl, amine, imine, nitrile, mercapto, nitro, halogen, C 1-12 Alkyl, C 6-12 Aryl, C 1-12 Alkoxy, hydroxy or a combination of these groups.

[0077] Preferred substituents are, for example, groups promoting solubility, such as alkyl or alkoxy groups, electron withdrawing groups, such as fluoro, nitro or nitrile groups, or groups for increasing the glass transition temperature (T g ), specifically a bulky group (e.g., a tert-butyl group or an optionally substituted aryl group).

[0078] Preferred substituents are F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R a )2, -C(=O)Y 1 、C(=O)R a 、-N(R a )2, where R a has the meaning indicated above, and Y 1represents halogen, optionally substituted silyl or aryl having 6 to 40, preferably 6 to 20 C atoms, and straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, wherein one or more H atoms may optionally be replaced by F or Cl.

[0079] More preferred substituents are, for example, F, Cl, CN, NO2, CH3, C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5, and phenyl.

[0080] In this document, the substituent L is, at each occurrence, identical or different, F, Cl, CN, SCN, SF5, N(R z )2 or straight-chain or branched, in each case optionally fluorinated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms.

[0081] Preference is given to L, on each occurrence, identically or differently, representing F or straight-chain or branched, in each case optionally fluorinated, alkyl or alkoxy having 1 to 7 C atoms.

[0082] "Substituted silyl or aryl" preferably means substituted silyl or aryl. y1 、-OR y1 、-CO-R y1 、-CO-OR y1 、-O-CO-R y1 OR-O-CO-OR y1 Substitution, where R y1 has the meaning indicated above.

[0083] In a preferred embodiment, Ar 1 and Ar 2 Preferably, identically or differently on each occurrence, represents aryl having 6 to 15 C atoms or heteroaryl having 2 to 15 C atoms, which may be substituted by one or more radicals L as defined above and below, where L is preferably F.

[0084] Ar 1 and Ar 2Particularly preferably, the radicals are selected identically or differently on each occurrence from the group which are optionally substituted with radicals L and in particular F, which are derived from the parent substances benzene, fluorene, naphthalene, pyridine, pyrimidine, pyridazine, thiophene, selenophene, thiazole, thiadiazole, benzothiadiazole, dihydrothienodioxin, benzothiophene, dibenzothiophene, benzodithiophene, cyclopentadithiophene, thienothiophene, indenothiophene, furan, benzofuran, dibenzofuran and quinoline, and even more preferably from the group consisting of benzene, naphthalene, thiadiazole, thienothiophene and thiophene.

[0085] In a particularly preferred embodiment, Ar 1 and Ar 2 independently of one another represents 1,4-phenylene, 1,4-naphthylene, 2,6-naphthylene, thiazole-2,5-diyl, thiophene-2,5-diyl or thienothiophene-2,5-diyl, where one or more H atoms may be replaced by a radical L as defined above and below.

[0086] Even more preferably, Ar 1 and Ar 2 represents, identically or differently on each occurrence, 1,4-phenylene, thiophene-2,5-diyl or thienothiophene-2,5-diyl, where one or more H atoms may be replaced by a radical L as defined above and below, where L preferably represents F.

[0087] Particularly preferred are compounds of formula I and II wherein Ar 1 At least one of them is thiophene-2,5-diyl or thienothiophene-2,5-diyl, and more preferably thiophene-2,5-diyl.

[0088] In another embodiment, it is preferred that in one or more compounds of formula I, a and b are 0 and Ar 1 At least one of them is thienothiophene-2,5-diyl.

[0089] In another embodiment, it is preferred that in one or more compounds of formula II, c and d are 0 and Ar 1 At least one of them is thienothiophene-2,5-diyl.

[0090] In a preferred embodiment, Z 1 represents, identically or differently on each occurrence, a single bond, -CH=CH-, -CF=CF- or -C≡C-. Particularly preferably, Z 1 Indicates a single bond.

[0091] Preferably, Z 2 Indicates a single bond.

[0092] Preferably, R 1In each occurrence, N(R z )2 or a straight-chain or branched alkyl or alkoxy radical having 1 to 20 C atoms, in which one or more H atoms may be replaced by F, and in which R z has the meaning given above and below.

[0093] It is particularly preferred that R 1 represent, identically or differently, a straight-chain or branched, preferably branched, alkyl or alkoxy radical having 1 to 15 C atoms, or N(R a )2, where R a independently of one another represent straight-chain alkyl radicals having 1 to 9 C atoms, preferably ethyl, butyl and hexyl.

[0094] In one embodiment, R 1 represents, identically or differently on each occurrence, a branched alkyl radical having 3 to 20 C atoms, preferably 3 to 12 C atoms, in which one or more H atoms may be replaced by F, one or more CH2 groups may be replaced by O and / or one or more CH groups may be replaced by N.

[0095] In a preferred embodiment, R 1 represents an alkyl group, preferably containing a methyl, ethyl, n-propyl, n-butyl or n-pentyl group bonded to an ethyl, n-propyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl or n-undecyl group, for example, 2-ethylhexyl, 2-ethylheptyl, 2-ethyloctyl, 2-ethylnonyl, 2-ethyldecyl, 3-ethylhexyl, 3-ethylheptyl, 3-ethyloctyl, 3-ethylnonyl, 3-ethyldecyl and the like.

[0096] In a particularly preferred embodiment, R 1 represents, identically or differently on each occurrence, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, ethoxy, n-propoxy, n-butoxy, n-pentyl, n-hexyl, n-heptyl or branched alkyl or alkoxy having 3 to 12 C atoms.

[0097] In another preferred embodiment, the group R 1 It represents a straight-chain or branched alkyl or dialkylamino group having 1 to 12 C atoms per alkyl group.

[0098] Preferably, R 2 represents, identically or differently on each occurrence, straight-chain or branched alkyl or alkoxy having 1 to 9 C atoms, preferably ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl and in particular ethyl.

[0099] Preferably, R zIt represents a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group or an n-nonyl group, and more preferably an ethyl group, an n-butyl group or an n-hexyl group.

[0100] Group R x1 and R x2 Preferably, identically or differently on each occurrence, it is H, F or alkyl having 1 to 6 C atoms, more preferably H or F and in particular H.

[0101] In a preferred embodiment, a, b, c and d all represent 1. However, in alternative embodiments, it is also possible that at least one of a and b represents 0 and / or at least one of c and d represents 0. It is thus also possible that both a and b are 0 and / or both c and d are 0. In the case that one of a and b is 1 and the other is 0 and similarly for c and d, an asymmetric compound is obtained.

[0102] In a preferred embodiment, at least one of X represents CR a , preferably both groups X represent CR a , where preferably R a is alkyl having 1 to 4 C atoms or H, and is especially H. It is particularly preferred that both X represent CR a , where R a is H. However, in an alternative embodiment, one or both groups X are N.

[0103] The compound of formula I is preferably selected from the compounds of formula Ia, Ib and Ic, and the compound of formula II is preferably selected from the compounds of formula Ila, Ilb and Ic,

[0104]

[0105]

[0106] wherein the variable groups have the meanings as described above for Formulae I and II, and wherein Z 1 and Z 2 Preferably represents a single bond and Ar 1 and Ar 2 Preferably, it is selected identically or differently on each occurrence from 1,4-phenylene, thiophene-2,5-diyl and thienothiophene-2,5-diyl, where these radicals may optionally be substituted by one or more Fs.

[0107] In one embodiment, a composition is provided, comprising one or more compounds selected from the group consisting of compounds of formula Ii, I-ii and I-iii, preferably at least one compound of formula Ii,

[0108]

[0109] and one or more compounds selected from the group consisting of compounds of formula III, II-ii and III-iii, preferably at least one compound of formula III,

[0110]

[0111] in

[0112] R 1 The same or different representations of H, F, CN, N(R z )2 or a straight-chain or branched alkyl or alkoxy radical having 1 to 20 C atoms, wherein, in addition, one or more non-adjacent CH2 groups can each independently of one another be connected via -C(R z )=C(R z )-、-C≡C-、 -N(R z )-, -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O-, and wherein, in addition, one or more H atoms may be replaced by F or CN,

[0113] R 2 and R z represents, identically or differently on each occurrence, H, halogen, straight-chain, branched or cyclic alkyl having 1 to 12 C atoms, wherein, in addition, one or more non-adjacent CH2 groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that the O and / or S atoms are not directly connected to one another, and wherein in addition, one or more H atoms may be replaced by F or Cl,

[0114] Ar 1 and Ar 2 represents, identically or differently on each occurrence, aryl or heteroaryl, which may be substituted by one or more radicals L,

[0115] L, in each occurrence, represents, identically or differently, F, Cl, CN, OH, SCN, SF5, N(R z )2 or in each case optionally fluorinated, straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms,

[0116] Z 1 represents a single bond, -O-, -S-, -C(O)-, -CR- y1 R y2-, -CF2O-, -OCF2-, -C(O)-O-, -OC(O)-, -OCH2-, -CH2O-, -CR x1 =CR x2 -、-C≡C-、-CR x1 =CR x2 -CO-, -CO-CR x1 =CR x2 -、-CR x1 =CR x2 -COO-, -OCO-CR x1 =CR x2 -or-N=N-,

[0117] R x1 , R x2 independently of one another represent H, F, Cl, CN or an alkyl radical having 1 to 12 C atoms,

[0118] R y1 represents H or an alkyl group having 1 to 12 C atoms, and

[0119] R y2 represents an alkyl group having 1 to 12 C atoms.

[0120] For the compounds of formula I-iii and formula II-iii, preferably, Ar 1 At least one of the groups Ar 1 All represent thienothiophene-2,5-diyl.

[0121] The compound of formula Ii is preferably selected from the compounds of formula Iia, Iib, Iic, Iid, Iie and Iif, more preferably selected from the compounds of formula Iia and Iic, and the compound of formula III is preferably selected from the compounds of formula IIIa, Iib, Iic, Iid, Iie and Iif, more preferably selected from the compounds of formula IIIa and Iic

[0122]

[0123]

[0124]

[0125] Where R 1 ,Ar 2 , Z 1 and R 2 has the meaning as described above for Formula I and II, and wherein Z 1 Preferably represents a single bond and Ar2 Preferably, it is selected identically or differently on each occurrence from 1,4-phenylene and thiophene-2,5-diyl, whereby these radicals may optionally be substituted by one or more F radicals.

[0126] The liquid-crystalline media according to the invention preferably comprise one or more compounds selected from the group of compounds of the formula Iia and / or Iic and one or more compounds of the formula IIIa.

[0127] In a preferred embodiment, the compound of formula I is selected from the compounds of formula Iia-1, Iia-2 and Iic-1, and the compound of formula II is selected from the compounds of formula Iia-1 and Iia-2

[0128]

[0129]

[0130] Where R 1 has the meaning as described for Formula I and R 2 has the meaning as described for Formula II.

[0131] In a particularly preferred embodiment, the composition according to the invention comprises at least one compound, preferably two or more compounds, selected from the group consisting of compounds of the formulae I-1, I-2, I-3 and I-4.

[0132]

[0133] and at least one compound, preferably two or more compounds, selected from the group consisting of compounds of formula II-1, II-2, II-3, II-4 and II-5,

[0134]

[0135]

[0136] Preferably, the composition contains two or more compounds of formula I, preferably three or more compounds of formula I and more preferably four or more compounds of formula I, especially the individual preferred subformulae as described above and below.

[0137] Preferably, the composition contains two or more compounds of formula II, preferably three or more compounds of formula II and more preferably four or more compounds of formula II, especially the individual preferred subformulae as described above and below.

[0138] In a particularly preferred embodiment, the composition contains two, three or four, preferably three or four and especially three compounds of the formula I-1, I-2, I-3 and I-4, and two or more, preferably two, three or four, compounds of the formula II-1, II-2, II-3, II-4 and II-5.

[0139] Due to favorable compatibility, the compounds of formula I and formula II and the various preferred subformulae as described above can be mixed in essentially any desired ratio. Typically, the ratio of the amount of the compound contained in the composition in the lowest amount to the amount of the compound contained in the composition in the highest amount is in the range of 1:1 to 1:100, preferably 1:1 to 1:10.

[0140] The compounds of formula I and formula II and the amounts of the individual compounds and the individual preferred subformulae as described above and below to be included in the composition may advantageously be selected and mixed so that the desired or required color effect for a given application is obtained.

[0141] In one embodiment, the composition contains compounds having red, green and blue colors, respectively. In a preferred embodiment, the compounds in the composition have absorption that together cover the entire visible spectrum. In this way, a neutral or black appearance can be obtained. Such a neutral color appearance can be advantageous in applications where color artifacts or residual colors should be minimized or avoided, such as in certain smart window applications.

[0142] It has further been found that it may be advantageous to include one or more near infrared dyes in the composition. This provision may advantageously facilitate minimizing or even avoiding residual fluorescence in the visible spectrum, such that unwanted color artifacts, such as red glow, may be avoided or at least significantly reduced.

[0143] In a particularly preferred embodiment, the composition comprises at least one violet dye, at least one blue dye, at least one yellow dye, at least one red dye and at least one near-infrared dye.

[0144] Preferably, the composition and the liquid-crystalline medium according to the invention comprise one or more, preferably two or more, more preferably three or more and even more preferably four or more compounds selected from the group of the following compounds (1) to (310):

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151]

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162]

[0163]

[0164]

[0165]

[0166]

[0167]

[0168]

[0169]

[0170]

[0171]

[0172]

[0173]

[0174]

[0175]

[0176]

[0177]

[0178]

[0179]

[0180]

[0181]

[0182]

[0183]

[0184]

[0185]

[0186]

[0187]

[0188]

[0189]

[0190]

[0191]

[0192] The compounds of formula I and formula II can be prepared by methods known per se or by methods analogous to known methods, as described in the literature (for example in standard works such as Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), under reaction conditions known and suitable for the reactions described. Variants known per se but not mentioned in greater detail here may also be used.

[0193] The compounds of the formulae I and II are preferably positive dichroic dyes, ie dyes having a positive anisotropy R.

[0194] The degree of anisotropy R of an LC mixture comprising a dye is determined by the values ​​of the extinction coefficients of the molecules aligned parallel and perpendicular to the polarization direction of the light.

[0195] According to the invention, the anisotropy R is preferably greater than 0.4, more preferably greater than 0.6, even more preferably greater than 0.7 and in particular greater than 0.8.

[0196] The absorptivity preferably reaches a maximum value when the polarization direction of light is parallel to the longest molecular extension direction of the compounds of formula I and formula II, and reaches a minimum value when the polarization direction of light is perpendicular to the longest molecular extension direction of the compounds of formula I and formula II.

[0197] The compounds of the formula I and formula II contained in the composition according to the invention can advantageously be used as guest compounds in liquid-crystalline host mixtures, in particular as dichroic dyes.

[0198] It has been unexpectedly found that the overall composition containing the combination of dichroic dye compounds according to the present invention can exhibit excellent solubility in liquid crystal media. This can ensure that meaningful and effective concentrations of the dyes in the LC medium can be achieved, which can advantageously contribute to the achievable contrast ratios and switching performances in switchable devices.

[0199] In an advantageous aspect of the present invention, therefore, there is provided a liquid-crystalline medium which, in addition to the composition according to the invention, further comprises one or more mesogenic compounds.

[0200] Preferably, the compounds of the composition are present in a liquid crystal medium in solution.

[0201] In principle, suitable host mixtures are any negative or positive dielectric LC mixtures which are suitable for use in conventional VA, TN, STN, IPS or FFS displays.

[0202] Suitable LC mixtures are known in the art and described in the literature.LC media for VA displays having negative dielectric anisotropy are described, for example, in EP 1 378 557 A1.

[0203] Suitable LC mixtures with positive dielectric anisotropy for LCDs and in particular for IPS displays are known, for example, from JP 07-181 439 (A), EP 0 667 555, EP 0 673986, DE 195 09 410, DE 195 28 106, DE 195 28 107, WO 96 / 23851, WO 96 / 28 521 and WO 2012 / 079676.

[0204] Preferred embodiments of the liquid-crystalline media according to the invention having negative or positive dielectric anisotropy are indicated below.

[0205] The LC host mixture is preferably a nematic LC mixture and preferably has no chiral LC phase.

[0206] In a preferred embodiment of the present invention, the LC medium contains an LC host mixture having a negative dielectric anisotropy. Therefore, in a preferred embodiment, the mesogenic medium according to the present invention comprises a component selected from the following items a) to w):

[0207] a) a mesogenic medium comprising one or more compounds selected from the group of compounds of formula CY, PY and AC:

[0208]

[0209] in

[0210] a means 1 or 2,

[0211] b represents 0 or 1,

[0212] c is 0, 1, or 2,

[0213] d is 0 or 1,

[0214] express

[0215]

[0216] and

[0217] express

[0218]

[0219] express

[0220]

[0221] R 1 and R 2

[0222] R AC1 and R AC2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0223] Z xand Z y each independently represents -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, preferably a single bond,

[0224] L 1-4 Each independently represents F, Cl, CN, OCF3, CF3, CH3, CH2F, CHF2.

[0225] The various groups have the following meanings:

[0226] each independently of one another represents an alkyl radical having 1 to 12 C atoms, furthermore one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -O-CO- or -CO-O- in such a way that the O atoms are not directly connected to one another,

[0227] Z AC represents -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, preferably a single bond, and

[0228] Preferably, L 1 and L 2 Both represent F, or L 1 and L 2 One of them represents F and the other represents Cl, or L 3 and L 4 Both represent F, or L 3 and L 4 One of them represents F and the other represents Cl.

[0229] The compound of formula CY is preferably selected from the group consisting of the following subformulae:

[0230]

[0231]

[0232]

[0233]

[0234]

[0235] wherein a represents 1 or 2, alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl group having 2 to 6 C atoms, and (O) represents an oxygen atom or a single bond. Alkenyl preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0236] The compound of formula PY is preferably selected from the group consisting of the following subformulae:

[0237]

[0238]

[0239]

[0240]

[0241] wherein alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl group having 2 to 6 C atoms, and (O) represents an oxygen atom or a single bond. Alkenyl preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0242] The compound of formula AC is preferably selected from the group of compounds of the following sub-formulae:

[0243]

[0244] b) a mesogenic medium which additionally comprises one or more compounds of the formula:

[0245]

[0246] The various groups have the following meanings:

[0247] express

[0248]

[0249] express

[0250] R 3 and R 4 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups may furthermore be replaced by -O-, -CH=CH-, -CO-, -O-CO- or -CO-O- in such a way that the O atoms are not directly connected to one another,

[0251] Z y It represents -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, preferably a single bond.

[0252] The compound of formula ZK is preferably selected from the group consisting of the following subformulae:

[0253]

[0254]

[0255] wherein alkyl and a lkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl group having 2 to 6 C atoms. A lkenyl preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0256] Particularly preferred are compounds of formulae ZK1 and ZK3.

[0257] Particularly preferred compounds of formula ZK are selected from the following subformulae:

[0258]

[0259] Among them, propyl, butyl and pentyl are straight chain groups.

[0260] Most preferred are compounds of formula ZK1a and ZK3a.

[0261] c) a mesogenic medium which additionally comprises one or more compounds of the formula:

[0262]

[0263] where the individual radicals have the following meanings on each occurrence, identically or differently:

[0264] R 5 and R 6each independently of one another represents an alkyl radical having 1 to 12 C atoms, in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0265] express

[0266] express and

[0267] e represents 1 or 2.

[0268] The compound of formula DK is preferably selected from the group consisting of the following subformulae:

[0269]

[0270]

[0271] wherein alkyl and a lkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl group having 2 to 6 C atoms. A lkenyl preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0272] Preferred are compounds of formula DK1, DK4, DK7, DK9, DK10 and DK11.

[0273] d) a mesogenic medium which additionally comprises one or more compounds of the formula:

[0274]

[0275] The various groups have the following meanings:

[0276] express

[0277] wherein at least one ring F is different from cyclohexylene,

[0278] f means 1 or 2,

[0279] R 1 and R 2each independently of one another represents an alkyl radical having 1 to 12 C atoms, furthermore one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another,

[0280] Z x represents -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, preferably a single bond,

[0281] L 1 and L 2 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2.

[0282] Preferably, the two groups L 1 and L 2 represents F, or group L 1 and L 2 One of them represents F and the other represents Cl.

[0283] The compound of formula LY is preferably selected from the group consisting of the following subformulae:

[0284]

[0285]

[0286]

[0287]

[0288] Where R 1 has the meaning indicated above, alkyl represents a straight-chain alkyl group having 1-6 C atoms, (O) represents an oxygen atom or a single bond, and v represents an integer from 1 to 6. 1 Preferably, it represents a straight-chain alkyl group having 1 to 6 C atoms or a straight-chain alkenyl group having 2 to 6 C atoms, specifically CH3, C2H5, n-C3H7, n-C4H9, n-C5H 11 , CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0289] e) A mesogenic medium which additionally comprises one or more compounds selected from the group consisting of the following subformulae:

[0290]

[0291]

[0292] Where a lkyl represents C 1-6 -alkyl, L x represents H or F, and X represents F, Cl, OCF3, OCHF2 or OCH=CF2. Particularly preferred are compounds of formula G1 in which X represents F.

[0293] f) a mesogenic medium which additionally comprises one or more compounds selected from the group consisting of the following subformulae:

[0294]

[0295]

[0296]

[0297] Where R 5 With the above for R 1 One of the indicated meanings, alkyl means C 1-6 -alkyl, d represents 0 or 1, and z and m each independently represent an integer of 1 to 6. 5 C is particularly preferred 1-6 -alkyl or C 1-6 -alkoxy or C 2-6 -alkenyl, d is preferably 1. The LC media according to the invention preferably comprise one or more compounds of the abovementioned formulae in an amount of ≥5% by weight.

[0298] g) a mesogenic medium which additionally comprises one or more biphenyl compounds selected from the group consisting of the following sub-formulae:

[0299]

[0300] wherein alkyl and alkenyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl and alkenyl* each independently represent a straight-chain alkenyl group having 2 to 6 C atoms. Alkenyl and alkenyl* preferably represent CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0301] The biphenyl ratio of the formula B1 to B3 in the LC mixture is preferably at least 3% by weight, in particular ≥5% by weight.

[0302] Compounds of formula B2 are especially preferred.

[0303] The compounds of the formulae B1 to B3 are preferably selected from the group consisting of the following subformulae:

[0304]

[0305] Therein, alkyl* denotes an alkyl radical having 1 to 6 C atoms. The medium according to the invention particularly preferably comprises one or more compounds of the formula B1a and / or B2c.

[0306] h) a mesogenic medium which additionally comprises one or more terphenyl compounds of the formula:

[0307]

[0308] Where R 5 and R 6 Each independently has one of the meanings indicated above, and

[0309]

[0310] Each independently expresses

[0311]

[0312] Where L 5 represents F or Cl, preferably F, and L 6 It represents F, Cl, OCF3, CF3, CH3, CH2F or CHF2, preferably F.

[0313] The compound of formula T is preferably selected from the group consisting of the following subformulae:

[0314]

[0315]

[0316]

[0317] wherein R represents a straight-chain alkyl or alkoxy group having 1 to 7 C atoms, R* represents a straight-chain alkenyl group having 2 to 7 C atoms, (O) represents an oxygen atom or a single bond, and m represents an integer from 1 to 6. R* preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0318] R preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentoxy.

[0319] i) a mesogenic medium which additionally comprises one or more compounds of the following formula O:

[0320]

[0321] in

[0322] express

[0323]

[0324] express

[0325]

[0326] R O1 , R O2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, furthermore one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another,

[0327] Z O1 represents -CH2CH2-, -CF2CF2-, -C=C- or a single bond,

[0328] Z O2 represents CH2O, -C(O)O-, -CH2CH2-, -CF2CF2- or a single bond,

[0329] o is 1 or 2.

[0330] The compound of formula O is preferably selected from the group consisting of the following subformulae:

[0331]

[0332]

[0333] Where R O1 and R O2 has the meanings indicated above and preferably each independently of one another denotes straight-chain alkyl having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms.

[0334] Preferred media comprise one or more compounds selected from the group consisting of formulae O3, O4 and O5.

[0335] k) Mesogenic media which additionally preferably comprise in an amount of >3% by weight, in particular ≥5% by weight and very particularly preferably from 5 to 30% by weight, one or more compounds of the formula:

[0336]

[0337] in

[0338] express

[0339]

[0340] R 9 represents H, CH3, C2H5 or n-C3H7, (F) represents an optional fluorine substituent, and q represents 1, 2 or 3, and R 7 With R 1 One of the indicated meanings.

[0341] Particularly preferred compounds of formula FI are selected from the group consisting of the following subformulae:

[0342]

[0343]

[0344] Where R 7 Preferably represents a straight chain alkyl group, and R 9 represents CH3, C2H5 or n-C3H7. Particularly preferred are compounds of formula FI1, FI2 and FI3.

[0345] 1) A mesogenic medium which additionally comprises one or more compounds selected from the group consisting of the following subformulae:

[0346]

[0347] Where R 8 With R 1 The alkyl radicals are defined as follows, and alkyl represents a straight-chain alkyl radical having 1 to 6 C atoms.

[0348] m) a mesogenic medium which additionally comprises one or more compounds containing tetrahydronaphthyl or naphthyl units, for example compounds selected from the group consisting of the following sub-formulae:

[0349]

[0350]

[0351]

[0352] in

[0353] R 10 and R 11 each independently of one another represents an alkyl radical having 1 to 12 C atoms, in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0354] And R 10 and R 11 preferably represents a straight-chain alkyl or alkoxy radical having 1 to 6 C atoms or a straight-chain alkenyl radical having 2 to 6 C atoms, and

[0355] Z 1 and Z 2 Each independently represents -C2H4-, -CH=CH-, -(CH2)4-, -(CH2)3O-, -O(CH2)3-, -CH=CH-CH2CH2-, -CH2CH2CH=CH-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CF=CH-, -CH=CF-, -CH2- or a single bond.

[0356] n) a mesogenic medium which additionally comprises one or more difluorodibenzochromans and / or chromans of the following formula:

[0357]

[0358] in

[0359] R 11 and R 12 Each independently has the above for R 11 One of the meanings indicated, ring M represents trans-1,4-cyclohexylene or 1,4-phenylene,

[0360] Z m is -C2H4-, -CH2O-, -OCH2-, -CO-O- or -O-CO-,

[0361] c is 0, 1, or 2,

[0362] The amount thereof is preferably in an amount of 3 to 20% by weight, specifically 3 to 15% by weight.

[0363] Particularly preferred compounds of formula BC, CR and RC are selected from the group consisting of the following subformulae:

[0364]

[0365]

[0366]

[0367] wherein alkyl and a lkenyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, (O) represents an oxygen atom or a single bond, c is 1 or 2, and alkenyl and a lkenyl* each independently represent a straight-chain alkenyl group having 2 to 6 C atoms. a lkenyl and a lkenyl* preferably represent CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0368] Very particular preference is given to mixtures comprising one, two or three compounds of the formula BC-2.

[0369] o) a mesomorphous medium which additionally comprises one or more fluorinated phenanthrenes and / or dibenzofurans of the following formula:

[0370]

[0371] Where R 11 and R 12 Each independently has one of the meanings indicated above for R 11 , b represents 0 or 1, L represents F, and r represents 1, 2 or 3.

[0372] Particularly preferred compounds of formula PH and BF are selected from the group consisting of the following subformulae:

[0373]

[0374]

[0375] wherein R and R' each independently represent a straight-chain alkyl or alkoxy group having 1 to 7 C atoms.

[0376] p) a mesogenic medium which additionally comprises one or more monocyclic compounds of the formula

[0377]

[0378] in

[0379] R 1 and R 2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0380] L 1 and L 2 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2.

[0381] Preferably, L 1 and L 2 Both represent F, or L 1 and L 2 One of them represents F and the other represents Cl.

[0382] The compound of formula Y is preferably selected from the group consisting of the following subformulae:

[0383]

[0384]

[0385] wherein Alkyl and Alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, Alkoxy represents a straight-chain alkoxy group having 1 to 6 C atoms, Alkenyl and Alkenyl* each independently represent a straight-chain alkenyl group having 2 to 6 C atoms, and O represents an oxygen atom or a single bond. Alkenyl and Alkenyl* preferably represent CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0386] Particularly preferred compounds of formula Y are selected from the group consisting of the following subformulae:

[0387]

[0388] Alkoxy preferably denotes straight-chain alkoxy having 3, 4 or 5 C atoms.

[0389] q) mesogenic medium comprising 1 to 15, preferably 3 to 12, compounds of the formula CY1, CY2, PY1, PY2, AC1, AC2 and / or AC3. The proportion of these compounds as a whole in the mixture is preferably 20 to 99%, more preferably 30 to 95%, particularly preferably 40 to 90%. The content of these individual compounds is preferably in each case 2 to 20%.

[0390] r) A mesogenic medium comprising 1 to 10, preferably 1 to 8, compounds of the formula ZK, in particular compounds of the formula ZK1, ZK2 and / or ZK6. The proportion of these compounds as a whole in the mixture is preferably 3 to 25%, particularly preferably 5 to 45%. The content of these individual compounds is preferably in each case 2 to 20%.

[0391] s) Mesogenic media in which the proportion of compounds of the formulae CY, PY and ZK in the mixture as a whole is greater than 70%, preferably greater than 80%.

[0392] t) A mesogenic medium containing one or more, preferably 1 to 5, compounds selected from the group consisting of the formulae PY1 to PY8, very particularly preferably the formula PY2. The proportion of these compounds as a whole in the mixture is preferably 1 to 30%, particularly preferably 2 to 20%. The content of these individual compounds is preferably in each case 1 to 20%.

[0393] u) A mesogenic medium comprising one or more, preferably 1, 2 or 3, compounds of the formula T2. The content of these compounds in the mixture as a whole is preferably 1 to 20%.

[0394] The LC media according to the invention preferably comprise terphenyl of the formula T and preferably subformulae thereof in an amount of 0.5 to 30% by weight, in particular 1 to 20% by weight.

[0395] Particularly preferred are compounds of the formulae T1, T2, T3 and T21. In these compounds, R preferably represents alkyl, furthermore alkoxy, each having 1 to 5 C atoms.

[0396] Terphenyl is preferably used in the mixture according to the invention if a Δn value of ≥ 0.1 is to be achieved in the mixture. Preferably the mixture comprises 2-20% by weight of one or more terphenyl compounds of the formula T, preferably selected from the group of compounds T1 to T22.

[0397] v) Mesogenic medium containing one or more, preferably 1, 2 or 3, compounds of the formula BF1 and / or BSF1. The total content of these compounds in the mixture as a whole is preferably 1 to 15%, preferably 2 to 10%, particularly preferably 4 to 8%.

[0398] v) Preferred media comprise one or more compounds of the formula O, preferably selected from the group consisting of the formulae O3, O4 and O5, in a total concentration of 2 to 25%, preferably 3 to 20%, particularly preferably 5 to 15%.

[0399] w) The preferred medium comprises one or more compounds of the formula DK, preferably selected from the group consisting of the compounds of the formula DK1, DK4, DK7, DK9, DK10 and DK11. The total concentration of the compounds of the formula DK9, DK10 and DK11 is preferably 2 to 25%, more preferably 3 to 20%, particularly preferably 5 to 15%.

[0400] In another preferred embodiment of the present invention, the LC medium contains an LC host mixture having positive dielectric anisotropy. Therefore, in a further preferred embodiment, the mesogenic medium according to the present invention comprises a component selected from the following items aa) to zz):

[0401] aa) a mesogenic medium comprising one or more compounds selected from the group of compounds of formulae IIA to VIII as described below, in particular compounds of formulae IIA and III

[0402]

[0403] in

[0404] R 20 each identically or differently represents a halogenated or unsubstituted alkyl or alkoxy group having 1 to 15 C atoms, wherein one or more CH2 groups in these groups may be independently connected to each other via -C≡C-, -CF2O-, -CH=CH-, -C≡C-, -C≡O-, -C≡ ... -O-, -CO-O- or -O-CO-,

[0405] X 20 each identically or differently represents F, Cl, CN, SF5, SCN, NCS, a halogenated alkyl, a halogenated alkenyl, a halogenated alkoxy or a halogenated alkenyloxy, each having up to 6 C atoms, and

[0406] Y 20-24 each identically or differently represents H or F;

[0407] Each independently expresses

[0408]

[0409] The compound of formula IIA is preferably selected from the following formulae:

[0410]

[0411]

[0412] Where R 20 and X 20 has the meaning indicated above.

[0413] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably X represents F. Particularly preferred are compounds of the formulae IIAa and IIAb, in particular compounds of the formulae IIAa and IIAb in which X represents F.

[0414] The compound of formula III is preferably selected from the following formulae:

[0415]

[0416]

[0417] Where R 20 and X 20 has the meaning indicated above.

[0418] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably represents F. Particularly preferred are compounds of formula IIIa and IIIe, specifically compounds of formula IIIa;

[0419] bb) The mesogenic medium may alternatively, or additionally, comprise one or more compounds selected from the following formulae:

[0420]

[0421] in

[0422] R 20 , X 20 and Y 20-23 has the meaning indicated above, and

[0423] Z 20 represents -C2H4-, -(CH2)4-, -CH=CH-, -CF=CF-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH2O-, -OCH2-, -COO- or -OCF2-, and also represents a single bond in formulas V and VI, and also represents -CF2O- in formulas V and VIII,

[0424] r represents 0 or 1, and

[0425] s represents 0 or 1;

[0426] - The compound of formula IV is preferably selected from the following formulae:

[0427]

[0428] Where R 20 and X 20 has the meaning indicated above.

[0429] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably represents F, CN or OCF3, furthermore OCF=CF2 or Cl;

[0430] - The compound of formula V is preferably selected from the following formulae:

[0431]

[0432]

[0433] Where R 20 and X 20 has the meaning indicated above.

[0434] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably represents F and OCF3, in addition OCHF2, CF3, OCF=CF2 and OCH=CF2;

[0435] - The compound of formula VI is preferably selected from the following formulae:

[0436]

[0437] Where R 20 and X 20 has the meaning indicated above.

[0438] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably represents F, in addition OCF3, CF3, CF=CF2, OCHF2 and OCH=CF2;

[0439] - The compound of formula VII is preferably selected from the following formulae:

[0440]

[0441] Where R 20 and X 20 has the meaning indicated above.

[0442] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably, it represents F, and furthermore, OCF3, OCHF2 and OCH=CF2.

[0443] cc) a mesogenic medium which further comprises one or more compounds selected from the group consisting of formulae ZK1 to ZK10 given above. Particularly preferred are compounds of formulae ZK1 and ZK3. Particularly preferred compounds of formula ZK are selected from the group consisting of subformulae ZK1a, ZK1b, ZK1c, ZK3a, ZK3b, ZK3c and ZK3d.

[0444] dd) The mesogenic medium further comprises one or more compounds selected from the group consisting of the formulae DK1 to DK12 given above. Particularly preferred compounds are DK1, DK4, DK7, DK9, DK10 and DK11.

[0445] ee) the mesogenic medium further comprises one or more compounds selected from the following formulae:

[0446]

[0447] Where X 20 has the meaning indicated above,

[0448] L means H or F, and

[0449] "Alkenyl" means C 2-6 -alkenyl.

[0450] ff) The compounds of formula DK-3a and IX are preferably selected from the following formulae:

[0451]

[0452] Among them, "alkyl" means C 1-6 -alkyl, preferably n-C3H7, n-C4H9 or n-C5H 11 , specifically n-C3H7.

[0453] gg) The medium further comprises one or more compounds selected from the formulae B1, B2 and B3 given above, preferably from the formula B2. The compounds of the formulae B1 to B3 are particularly preferably selected from the formulae B1a, B2a, B2b and B2c.

[0454] hh) the medium further comprises one or more compounds selected from the following formulae:

[0455]

[0456] Where L 20 , L 21 indicates H or F, and R 21 And R 22 each identically or differently represents n-alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms, and preferably each identically or differently represents alkyl having 1 to 6 C atoms.

[0457] ii) the medium comprises one or more compounds of the following formula:

[0458]

[0459] Where R 20 , X 20 and Y 20-23has the meaning indicated in formula III, and

[0460] Each independently expresses

[0461]

[0462] and

[0463] express

[0464]

[0465] The compounds of formula XI and XII are preferably selected from the following formulae:

[0466]

[0467]

[0468] Where R 20 and X 20 has the meaning indicated above, and preferably R 20 represents an alkyl group having 1 to 6 C atoms and X 20 Indicates F.

[0469] The mixtures according to the invention particularly preferably comprise at least one compound of the formula XIIa and / or XIIe.

[0470] jj) The medium comprises one or more compounds of the formula T given above, preferably selected from the group of compounds of the formulae T21 to T23 and T25 to T27.

[0471] Particularly preferred are compounds of the formulae T21 to T23. Very particularly preferred are compounds of the formula

[0472]

[0473] kk) The medium comprises one or more compounds selected from the group of formulae DK9, DK10 and DK11 given above.

[0474] 11) The medium further comprises one or more compounds selected from the following formulae:

[0475]

[0476] Where R 20 and X 20 Each independently has one of the meanings indicated above, and Y 20-23 Each independently represents H or F. 20 Preferably it is F, Cl, CF3, OCF3 or OCHF2.20 Preferably it denotes alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms.

[0477] The mixtures according to the invention particularly preferably comprise one or more compounds of the formula XVIII-a,

[0478]

[0479] Where R 20 has the meaning indicated above. 20 Preferably denotes straight-chain alkyl, in particular ethyl, n-propyl, n-butyl and n-pentyl and very particularly preferably n-propyl. The compound(s) of formula XVIII, in particular formula XVIII-a, is / are preferably used in the mixture according to the invention in an amount of 0.5 to 20% by weight, particularly preferably 1 to 15% by weight.

[0480] mm) the medium additionally comprises one or more compounds of the formula XIX,

[0481]

[0482] Where R 20 , X 20 and Y 20-25 has the meaning indicated in formula III, s represents 0 or 1, and

[0483] express

[0484] In Formula XIX, X 20 It can also represent an alkyl group having 1 to 6 C atoms or an alkoxy group having 1 to 6 C atoms. The alkyl group or alkoxy group is preferably straight-chain.

[0485] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably F;

[0486] - The compound of formula XIX is preferably selected from the following formulae:

[0487]

[0488]

[0489] Where R 20 , X 20 and Y 20 has the meaning indicated above. 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably, F is represented, and Y 20 Preferably F;

[0490] Best

[0491]

[0492] -R 20 is a straight-chain alkyl or alkenyl group having 2 to 6 C atoms;

[0493] nn) the medium comprises one or more compounds of the formulae G1 to G4 given above, preferably selected from G1 and G2, wherein alkyl represents C 1-6 -alkyl, L x represents H and X represents F or Cl. In G2, X particularly preferably represents Cl.

[0494] oo) the medium comprises one or more compounds of the following formula:

[0495]

[0496]

[0497] Where R 20 and X 20 has the meaning indicated above. 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably represents F. The medium according to the invention particularly preferably comprises one or more compounds of the formula XXI I, in which X 20 Preferably it represents F. The compound(s) of the formulae XX-XXIII are preferably used in the mixture according to the invention in an amount of 1 to 20% by weight, particularly preferably 1 to 15% by weight. Particularly preferably, the mixture comprises at least one compound of the formula XIII.

[0498] pp) The medium contains one or more of the following pyrimidine compounds or pyridine compounds of the formula

[0499]

[0500] Where R 20 and X 20 has the meaning indicated above. 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably represents F. The medium according to the invention particularly preferably comprises one or more compounds of the formula M-1, in which X 20 Preferably it represents F. The compound(s) of the formulae M-1 to M-3 are preferably used in the mixture according to the invention in an amount of 1 to 20% by weight, particularly preferably 1 to 15% by weight.

[0501] qq) The medium comprises two or more compounds of formula XII, in particular formula XIIa and / or XIIe.

[0502] The rr) medium comprises 2 to 30% by weight, preferably 3 to 20% by weight, particularly preferably 3 to 15% by weight, of the compound of the formula XII.

[0503] ss) In addition to the compound of formula XII, the medium comprises a further compound selected from the group of compounds of formulae IIA to XVIII.

[0504] tt) The proportion of the compounds of the formulae IIA to XVIII in the mixture as a whole is 40 to 95% by weight, preferably 50 to 90% and particularly preferably 55 to 88% by weight.

[0505] The uu) medium preferably comprises 10 to 40% by weight, more preferably 12 to 30% and especially preferably 15 to 25% by weight of compounds of the formula IIA and / or III.

[0506] vv) The medium comprises 1 to 10% by weight, particularly preferably 2 to 7% by weight, of the compounds of the formula XV and / or XVI.

[0507] ww) The medium comprises at least one compound of the formula XIIa and / or at least one compound of the formula XIIe and at least one compound of the formula IIIa and / or IIAa.

[0508] xx) Preferred media comprise one or more compounds of the formula O, preferably selected from the formulae O3, O4 and O5, in a total concentration of 2 to 25%, preferably 3 to 20%, particularly preferably 5 to 15%.

[0509] yy) Preferred media contain one or more compounds of the formula DK, preferably selected from the group consisting of the compounds of the formulae DK1, DK4, DK7, DK9, DK10 and DK11. The total concentration of the compounds of the formulae DK9, DK10 and DK11 is preferably 2 to 25%, more preferably 3 to 20%, particularly preferably 5 to 15%.

[0510] zz) Preferred media comprise one or more compounds of the formulae IV to VI, preferably selected from the group of compounds of the formulae IVa, IVb, IVc, IVd, Va, Vc and VIb, in a concentration of 10 to 80% by weight, preferably 12 to 75% by weight, particularly preferably 15 to 70% by weight.

[0511] In the case of a medium having negative dielectric anisotropy, the dielectric anisotropy value (Δε) is preferably in the range of -2.0 to -8.0, more preferably in the range of -3.0 to -6.0, and particularly preferably -3.5 to -5.0.

[0512] In the case of a medium having positive dielectric anisotropy, the Δε value is preferably in the range of 3.0 to 60.0, more preferably in the range of 5.0 to 30.0, and particularly preferably 8.0 to 15.0.

[0513] The clearing point of the liquid-crystalline medium according to the invention is preferably 70° C. or higher, more preferably 80° C. or higher, even more preferably 90° C. or higher, still more preferably 105° C. or higher, and especially preferably 110° C. or higher. In one embodiment, the clearing point of the liquid-crystalline medium according to the invention is in the range of 70° C. to 170° C.

[0514] High definition bright spots as defined can be beneficial in terms of the performance and reliability of devices using liquid crystal media. In particular, the medium can maintain its functional properties over a wide temperature range and also at elevated temperatures. This can be particularly advantageous in window elements for regulating the transmission of daylight, especially when the window elements are exposed to direct or prolonged irradiation of daylight. High definition bright spots can also contribute to an advantageously high degree of ordering of the liquid crystal host molecules and thus to dichroic dye guest molecules at typical operating temperatures, which can increase the achievable contrast between switching states.

[0515] The clearing point, in particular the phase transition temperature between the nematic phase and the isotropic phase, can be measured and determined by generally known methods, for example using a Met tler oven, a hot stage under a polarizing microscope or differential scanning calorimetry (DSC) analysis. According to the present invention, preferably a Met tler oven is used to determine the clearing point.

[0516] The nematic phase of the medium according to the present invention preferably extends at least from -10°C or lower to 70°C or higher. Even broader nematic phase ranges are more preferred, in particular extending to 85°C or higher, more preferably at least from -20°C or lower to 100°C or higher, and particularly preferably from -30°C or lower to 110°C or higher.

[0517] In a preferred embodiment of the present invention, the birefringence (Δn) of the liquid crystal medium is in the range of 0.040 or more to 0.080 or less, more preferably in the range of 0.045 or more to 0.070 or less, and most preferably in the range of 0.050 or more to 0.060 or less. In this embodiment, the dielectric anisotropy is positive or negative, preferably negative.

[0518] In another preferred embodiment of the present invention, the Δn of the liquid crystal medium is in the range of 0.075 or more to 0.130 or less, more preferably in the range of 0.090 or more to 0.125 or less, and most preferably in the range of 0.095 or more to 0.120 or less.

[0519] In yet another preferred embodiment of the present invention, the Δn of the liquid crystal medium is in the range of 0.100 or more to 0.200 or less, more preferably in the range of 0.110 or more to 0.180 or less, and most preferably in the range of 0.120 or more to 0.160 or less.

[0520] Each of the one or more compounds selected from the group of compounds of the formula I and the one or more compounds selected from the group of compounds of the formula II as described above and below is preferably present in the liquid-crystalline medium in a proportion of 0.005% to 12.5% ​​by weight, more preferably 0.01% to 10% by weight, even more preferably 0.025% to 7.5% by weight, yet even more preferably 0.05% to 5% by weight, yet even more preferably 0.1% to 2.5% by weight and particularly preferably 0.25% to 1% by weight, based on the total weight of the entire medium.

[0521] Preferably, one or more compounds selected from the group of compounds of formula I and one or more compounds selected from the group of compounds of formula II are present in the overall liquid crystal medium in a total concentration in the range of 0.01% to 30% by weight, more preferably 0.025% to 25% by weight, even more preferably 0.05% to 15% by weight, even more preferably 0.1% to 10% by weight and particularly preferably 0.5% to 5% by weight.

[0522] The medium preferably comprises two, three, four, five, six, seven or eight compounds of the formula I and two, three, four, five, six, seven or eight compounds of the formula II.

[0523] The LC media according to the invention are preferably nematic liquid crystals.

[0524] However, in one embodiment, it is also possible to add chiral compounds (especially one or more chiral dopants) to the LC medium to produce chiral nematic or corresponding cholesteric LC media. In this respect, suitable chiral compounds and common procedures are known in the art, and Table F lists particularly preferred chiral compounds that can be added to the LC medium.

[0525] The medium according to the present invention is prepared in a conventional manner per se. Generally speaking, it is preferred to dissolve the components in each other at high temperatures. Mixing is preferably carried out under an inert atmosphere, for example under nitrogen or argon. Subsequently, preferably at high temperatures, more preferably at higher than 40° C. and especially preferably at higher than 50° C., the dyes of formula I and II and optional other dichroic dyes are added. Generally speaking, the components of the required amount used in smaller amounts are dissolved in the components constituting the main ingredients. It is also possible to mix solutions of the components in organic solvents (for example in acetone, toluene, chloroform or methanol), and for example remove the solvent again by distillation after mixing.

[0526] Furthermore, the invention relates to a process for preparing the liquid-crystalline medium according to the invention.

[0527] The invention further relates to the use of an LC medium comprising a composition according to the invention in a liquid crystal device of the guest-host type, wherein the device is in particular a window assembly or a display. In the device, the composition according to the invention and the medium are preferably provided in one or more switching layers.

[0528] The invention further relates to liquid-crystal displays of the guest-host type comprising an LC medium according to the invention.

[0529] The present invention furthermore relates to the use of a liquid-crystalline medium comprising a composition according to the invention in a device for regulating the transfer of energy from an external space into an internal space.

[0530] It is particularly preferred that the compositions and LC media according to the invention contain no further dyes, in particular no further dichroic dyes, besides the compounds of formulae I and II. This means that in this embodiment, the compositions and LC media comprise only dye compounds conforming to formulae I and II as currently defined.

[0531] In a preferred embodiment, the composition consists of one or more compounds of formula I and one or more compounds of formula II as defined herein.

[0532] However, in an alternative embodiment, the composition and the liquid-crystalline medium comprise, in addition to the compounds of formulae I and II, further dichroic dyes having a structure different from formulae I and II. In this case, the composition and the LC medium preferably comprise one, two, three or four further dyes having a structure different from formulae I and II, more preferably two or three further dyes and most preferably two further dyes.

[0533] With regard to the dichroic properties, the preferences stated for the compounds of the formulae I and II are also preferred for the optional further dichroic dyes.

[0534] The absorption spectra of the dichroic dyes of the composition, the LC medium and the LC medium in the exchange layer are preferably complementary to one another in such a way that the eye has the impression of black. The dyes of the liquid-crystalline medium according to the invention preferably cover a large part, more preferably the entire part, of the visible spectrum. The precise manner in which mixtures of dyes which appear black or grey to the eye can be prepared is known to the person skilled in the art and is described, for example, in M. Richter, Einführung in die Farbmetr ik [Introduction to Colorimetry], 2nd edition, 1981, ISBN 3-11-008209-8, Walter de Gruyter & Co.

[0535] The setting of the color positions of dye mixtures is described in the colorimetric area. For this purpose, the spectra of the individual dyes are calculated according to the Lambert-Beer law to obtain the total spectrum and converted into the corresponding color positions and brightness values ​​according to the colorimetric rules under the relevant illumination, for example the daylight illuminant D65. The position of the white point is fixed by the individual illuminants (for example D65) and is given in the table, for example in the reference above. Different color positions can be set by changing the ratio of the different dyes.

[0536] According to a preferred embodiment, the composition, the LC medium and the LC medium in the switching layer comprise one or more dichroic dyes which absorb light in the red and NIR region, i.e. at a wavelength in the range of 600 nm to 2000 nm, preferably in the range of 600 nm to 1800 nm, particularly preferably in the range of 650 nm to 1300 nm.

[0537] In case the composition and the LC medium contain at least one dichroic dye in addition to a compound selected from the group of compounds of formulae I and II, the at least one other dichroic dye is preferably selected from azo dyes, anthraquinones, methine compounds, azomethine compounds, merocyanidin compounds, naphthoquinones, tetrazines, perylenes, terrylenes, quaterrylenes, higher rylenes, pyrromethenes, thiadiazoles, nickel dithiolenes, (metal)phthalocyanines, (metal)naphthalocyanines and (metal)porphyrins. Of these, azo dyes and thiadiazoles are particularly preferred.

[0538] In one embodiment, the further dichroic dyes are preferably selected from the classes of dyes indicated in B. Bahadur, Liquid Crystals—Applications and Uses, Volume 3, 1992, World Scientific Publishing, Chapter 11.2.1, and particularly preferably from the explicit compounds given in the tables presented therein.

[0539] Said dyes belong to the class of dichroic dyes known to the person skilled in the art and have been described in the literature. Thus, for example, anthraquinone dyes are described in EP 34832, EP 44893, EP 48583, EP 54217, EP 56492, EP 59036, GB 2065158, GB 2065695, GB 2081736, GB 2082196, GB 2094822, GB 2094825, JP-A 55-123673, DE 3017877, DE 3040102, DE 3115147, DE 3115762, DE 3150803 and DE 3201120, naphthoquinone dyes are described in DE 3126108 and DE 3202761, azo dyes are described in EP 43904, DE 3123519, WO82 / 2054, GB 2079770, JP-A 56-57850, JP-A 56-104984, US 4308161, US 4308162, US4340973, T. Uchida, C. Shishido, H. Seki and M. Wada: Mol. Crys t. Lig. Crys t. 39, 39-52 (1977), and H. Seki, C. Shishido, S. Yasui and T. Uchida: Jpn. J. Appl. Phys. 21, 191-192 (1982), and perylene is described in EP 60895, EP 68427 and WO 82 / 1191. Rylene dyes are described, for example, in EP 2 166 040 , US 2011 / 0042651 , EP 68427 , EP 47027 , EP 60895 , DE 3110960 and EP 698649 .

[0540] Examples of preferred further dichroic dyes that may be present in the composition, LC medium and switching layer of the device are shown below

[0541]

[0542]

[0543]

[0544]

[0545]

[0546]

[0547] The compositions and liquid-crystalline media according to the invention may additionally comprise suitable additives and auxiliary materials.

[0548] In one embodiment, the composition and the LC medium comprise one or more quencher compounds. This is especially preferred if the composition and the medium comprise one or more fluorescent dyes.

[0549] Quencher compounds are compounds that quench fluorescence. In the process, the quencher compound can absorb the electronic excitation energy of adjacent molecules (e.g. fluorescent dyes) in the material and undergo transitions into an electronic excited state. The fluorescent dye to be quenched is thereby converted to an electronic ground state and is therefore prevented from emitting fluorescence or undergoing subsequent reactions. The quencher compound itself returns to the ground state via radiationless deactivation or by emitting light and can be used again for other quenching.

[0550] Quencher compounds can have various functions in the material. First, quencher compounds can help extend the lifetime of the dye system by deactivating electronic excitation energy. Second, quencher compounds can eliminate extra color effects.

[0551] The device of the invention is preferably suitable for regulating the transfer of energy in the form of daylight from the environment into the interior space.The energy transfer to be regulated here takes place from the environment, ie the exterior space, into the interior space.

[0552] An interior space here may be any desired space that is substantially isolated from the environment, such as a building, a vehicle or a container.

[0553] Therefore, the invention further relates to the use of a device for regulating the transfer of energy from an external space into an internal space.

[0554] However, the device can also be used for aesthetic room design, for example for light and color effects. For example, a gray or colored device according to the invention containing door and wall elements can be switched to transparent. In addition, the device can also contain a white or colored planar backlight for brightness adjustment or a yellow planar backlight for color adjustment by means of a blue object-host display. In the case of glass substrates used in the device, one or both glass sides of the device according to the invention can be provided with rough or structured glass for coupling out light and / or for generating light effects.

[0555] In a further alternative use, the device is used for regulating the incidence of light on the eye, for example in goggles, visors or sunglasses, wherein the device in one switching state keeps the incidence of light on the eye low and in another switching state reduces the incidence of light to a lesser extent.

[0556] The device of the present invention is preferably arranged in an opening of a relatively large two-dimensional structure, wherein the two-dimensional structure itself only allows energy to pass slightly or not at all, and wherein the opening has a relatively high energy transmittance. The two-dimensional structure is preferably a wall or another boundary from the interior space to the outside. In addition, the two-dimensional structure preferably covers an area at least equal to the size of the opening in which the device of the present invention is arranged, and particularly preferably at least twice the area.

[0557] The device is preferably characterized in that it has at least 0.05 m 2 , preferably at least 0.1m 2 , especially preferably at least 0.5m 2 and very particularly preferably at least 1.0 m 2 area.

[0558] The device is preferably housed in an opening with a relatively high energy transmittance in a building, container, vehicle or another substantially enclosed space, as described above. The device can generally be used in any desired interior space, especially if it has only limited air exchange with the environment and has a light-transmitting boundary surface into which energy in the form of light energy can be input from the outside. The device is particularly preferably used for interior spaces that are subjected to strong sunlight through light-transmitting areas (e.g. through window areas).

[0559] The device of the invention is switchable. Switching here means changing the passage of energy through the device. The device of the invention is preferably electrically switchable, as described, for example, in WO 2009 / 141295 and WO 2014 / 090373.

[0560] However, the device may also be thermally switchable, as described, for example, in WO 2010 / 118422. In this case, the switching is preferably carried out by a change in the temperature of the switching layer comprising the formula I and formula II in the liquid crystal medium from the nematic state to the isotropic state. In the nematic state, the molecules of the liquid crystal medium are in an ordered form, and therefore the compounds of the formula I and II, which are aligned parallel to the surface of the device, for example, via the action of the alignment layer, are also in an ordered form. In the isotropic state, the molecules are in a disordered form, and therefore the compounds of the formula I and II are also in a disordered form. The difference between the ordered and disordered presence of the dichroic compound causes a difference in the transmittance of the switching layer of the device according to the invention, according to the principle that the dichroic compound has a higher or lower absorption coefficient depending on the alignment with respect to the polarization plane of the light.

[0561] In case the device is electrically switchable, it preferably comprises two or more electrodes, which are preferably mounted on both sides of the switching layer. The electrodes preferably consist of ITO or a thin (preferably transparent) metal and / or metal oxide layer, such as silver or FTO (fluorine doped tin oxide) or alternative materials known in the art for this purpose. The electrodes preferably have electrical connections. The voltage is preferably provided by a battery, a rechargeable battery or an external power source, in particular an external power source.

[0562] In the case of electrical switching, the switching operation is performed by (re)aligning the molecules of the liquid-crystalline medium by applying an electrical voltage.

[0563] In a preferred embodiment, the device is converted from a state with high absorptivity (i.e. low transmittance) (which exists under no voltage) to a state with lower absorptivity (i.e. higher transmittance). The liquid crystal medium of the switching layer is preferably nematic in both states. The no voltage state is preferably characterized by the molecules of the liquid crystal medium, and therefore the molecules of the compounds of formula I and II being aligned parallel to the plane of the switching layer. This is preferably achieved by the corresponding selected alignment layer. The state of applied voltage is preferably characterized by the molecules of the liquid crystal medium, and therefore the molecules of the compounds of formula I and II being perpendicular to the plane of the switching layer.

[0564] In an alternative embodiment, the device is converted from a state with low absorptivity (i.e. high transmittance) (which exists under no voltage) to a state with higher absorptivity (i.e. lower transmittance). The liquid crystal medium of the switching layer is preferably nematic in both states. The no-voltage state is preferably characterized by the molecules of the liquid crystal medium of the switching layer, and therefore the molecules of the compounds of formula I and II are aligned perpendicular to the plane of the switching layer. This is preferably achieved by the corresponding selected alignment layer. The state of applied voltage is preferably characterized by the molecules of the liquid crystal medium of the switching layer, and therefore the molecules of the compounds of formula I and II are parallel to the plane of the switching layer.

[0565] The device according to the invention preferably has the following layer sequence, wherein further layers may additionally be present. The layers indicated below are preferably directly adjacent to one another in the device:

[0566] - a substrate layer, which preferably comprises glass or a polymer

[0567] - a conductive transparent layer, which preferably comprises ITO

[0568] - Alignment layer

[0569] a switching layer comprising the composition according to the invention, preferably an LC medium comprising said composition,

[0570] - Alignment layer

[0571] - a conductive transparent layer, which preferably comprises ITO

[0572] - A substrate layer, which preferably comprises glass or a polymer.

[0573] The device according to the invention preferably comprises one or more, particularly preferably two, alignment layers. The alignment layers preferably directly adjoin the switching layer comprising the compounds of the formulae I and II on both sides.

[0574] The alignment layer used in the device according to the present invention may be any desired layer known to the person skilled in the art for this purpose. Preferred are polyimide layers, particularly preferably layers comprising rubbed polyimide. In one embodiment, a planar alignment is provided, wherein more preferably a slight pretilt angle may be provided. In an alternative embodiment, a homeotropic alignment is provided, wherein more preferably a high pretilt angle is provided.

[0575] In addition, a polymer obtained by an exposure method to polarized light may be used as an alignment layer to achieve alignment of the compounds of the liquid crystal medium in accordance with the alignment axis (ie, photo-alignment).

[0576] The switching layer in the device of the invention is further more preferably arranged between or enclosed by two substrate layers. The substrate layers may consist, for example, of glass or a polymer, preferably a light-transmitting polymer.

[0577] The device is preferably characterized in that it contains no polymer-based polarizers, particularly preferably no polarizers in a solid material phase, and very particularly preferably no polarizers at all. Therefore, in a particularly preferred embodiment, the device, in particular the device for regulating the transfer of energy from an external space into an internal space, and the window element do not contain a polarizer.

[0578] However, according to an alternative embodiment, the device may also comprise one or more polarizers. In this case, the polarizer is preferably a linear polarizer. In this alternative embodiment, it is preferred that the device comprises only one polarizer. If there is exactly one polarizer, it is preferred to use a Heilmeier type guest-host configuration. Optionally, both absorptive and reflective polarizers may be employed. It is preferred to use a polarizer in the form of a thin optical film.

[0579] In a preferred embodiment, the device according to the invention is a component of a window, more preferably a component of a window comprising at least one glass surface, especially preferably a component of an insulating glass unit.

[0580] A window here means in particular a structure in a building, car, commercial vehicle, ship, train, airplane, etc., which comprises a frame and at least one substrate or pane, such as a plastic substrate or a glass pane, surrounded by the frame. In a preferred embodiment, in particular for architectural applications, the window preferably comprises an insulating frame and two or more glass panes, i.e. a multi-pane insulating glass.

[0581] According to a preferred embodiment, the device of the invention is applied directly to the glass surface of a window (eg by lamination), particularly preferably in the gap between two glass panes of a multi-pane insulating glass.

[0582] Furthermore, the invention relates to a window comprising a device according to the invention, which preferably has the preferred features indicated above.

[0583] Besides use as dyes, due to their electronic properties, the compositions according to the invention are also suitable as organic semiconductors.

[0584] The invention therefore furthermore relates to the use of the composition in organic electronic components, such as organic light emitting diodes (OLEDs), organic field effect transistors (OFETs), printed circuits, radio frequency identification elements (RFIDs), lighting elements, photovoltaic devices and optical sensors.

[0585] Due to the colored nature of the composition according to the invention and its good solubility in organic materials, it is particularly suitable as a dye composition. The invention therefore also relates to the use of the composition for the coloring of polymers.

[0586] In the present invention and in particular in the following examples, the structures of the mesogenic compounds are indicated with the aid of abbreviations (also called acronyms). In these acronyms, the chemical formulae are abbreviated as follows using the following Tables A to C. All radicals C n H 2n+1 , C m H 2m+1 and C l H 2l+1 or C n H 2n-1 , C m H 2m-1 and C l H 2l-1 All represent straight chain alkyl or alkenyl, preferably 1E-alkenyl, each of which has n, m and 1 C atoms, respectively. Table A lists the codes for the ring elements of the core structure of the compound, while Table B shows the linking groups. Table C gives the meaning of the codes for the left-hand or right-hand terminal groups. The acronyms are composed of the code for the ring element with the optional linking group, followed by the first hyphen and the code for the left-hand terminal group and the second hyphen and the code for the right-hand terminal group. Table D shows the illustrative structures of the compounds and their corresponding abbreviations.

[0587] Table A: Ring elements

[0588]

[0589]

[0590]

[0591] Table B: Linking Groups

[0592]

[0593] Table C: End Groups

[0594]

[0595]

[0596] Use with each other and with others

[0597]

[0598] where n and m each represent an integer, and the triple dots "..." are placeholders for other abbreviations from this table.

[0599] The following table shows illustrative structures and their respective abbreviations. These are shown to illustrate the meaning of the abbreviation conventions. In addition, they represent compounds that are preferably used.

[0600] Table D: Illustrative structure

[0601]

[0602]

[0603]

[0604]

[0605]

[0606]

[0607]

[0608]

[0609]

[0610]

[0611]

[0612]

[0613]

[0614]

[0615]

[0616]

[0617]

[0618]

[0619]

[0620]

[0621] wherein n, m and l preferably represent 1 to 9, more preferably 1 to 7, independently of one another.

[0622] The following table (Table E) shows illustrative compounds that may optionally be used as stabilizers in the mesogenic media of the present invention.

[0623] Table E

[0624] Table E shows possible stabilizers which can be added to the LC media according to the invention, wherein n represents an integer from 1 to 12, preferably 1, 2, 3, 4, 5, 6, 7 or 8.

[0625]

[0626]

[0627]

[0628]

[0629]

[0630]

[0631] The LC medium preferably comprises 0 to 10% by weight, in particular 1 ppm to 5% by weight, particularly preferably 10 ppm to 1% by weight, of stabilizer.

[0632] Table F below shows illustrative compounds which can preferably be used as chiral dopants in the mesogenic media according to the invention.

[0633] Table F

[0634]

[0635]

[0636]

[0637] In one embodiment of the present invention, the mesogenic medium comprises one or more compounds selected from the group of compounds from Table F.

[0638] The mesogenic medium according to the present invention preferably comprises two or more, preferably four or more, compounds selected from the group of compounds from Tables D, E and F above.

[0639] The liquid-crystalline media according to the invention preferably comprise seven or more, preferably eight or more, individual compounds selected from the group of compounds from Table D, preferably three or more, particularly preferably four or more, having different formulae selected from the formulae shown in Table D.

[0640] The LC media according to the invention may also comprise compounds in which, for example, H, N, O, Cl or F are substituted by corresponding isotopes.

[0641] Unless expressly indicated otherwise, all percentage data and amount ratios given herein are % by weight.

[0642] Unless expressly indicated otherwise, all physical properties are determined in accordance with "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status November 1997, Merck KGaA, Germany, and a temperature of 20° C. applies. Unless expressly indicated otherwise, the value of Δn is in each case determined at 589 nm and the value of Δε is determined at 1 kHz. e and n o In each case are the refractive indices of the extraordinary and ordinary beams under the conditions indicated above.

[0643] The degree of anisotropy R is determined from the values ​​of the extinction coefficient E(p) of the mixture (extinction coefficient of the mixture in the case where the molecules are aligned parallel to the polarization direction of the light) and the extinction coefficient E(s) (extinction coefficient of the mixture in the case where the molecules are aligned perpendicular to the polarization direction of the light), in each case at the wavelength of the maximum of the absorption band of the dye in question. If the dye has several absorption bands, the strongest absorption band is usually selected. The alignment of the molecules of the mixture is achieved by an alignment layer, as is known in the art. To eliminate the influence of the liquid crystal medium, other absorption or reflection, each measurement is carried out on the same mixture without dye, and the value obtained is subtracted.

[0644] The measurement is made using linearly polarized light with a vibration direction parallel to the alignment direction (determination of E(p)) or perpendicular to the alignment direction (determination of E(s)). This can be achieved by a linear polarizer, where the polarizer is rotated relative to the device to achieve two different polarization directions. The measurement of E(p) and E(s) is thus performed via the rotation of the polarization direction of the incident polarized light.

[0645] The anisotropy R is calculated from the values ​​of E(s) and E(p) according to the following formula:

[0646] R=[E(p)-E(s)] / [E(p)+2*E(s)],

[0647] As indicated in particular in "Polarized Light in Optics and Spectroscopy", DSKliger et al., Academic Press, 1990. A detailed description of a method for determining the degree of anisotropy of liquid-crystalline media comprising dichroic dyes is also given in B. Bahadur, Liquid Crystals—Applications and Uses, Volume 3, 1992, World Scientific Publishing, section 11.4.2.

[0648] The following examples are only used to illustrate the present invention, and they should not be considered to limit the scope of the present invention in any way.According to this disclosure, embodiments and variations or their other equivalents will become obvious to those skilled in the art. Example

[0649] In an embodiment,

[0650] V o represents the threshold voltage at 20°C, capacitive [V],

[0651] n e represents the extraordinary refractive index at 20°C and 589nm,

[0652] n o represents the ordinary refractive index at 20°C and 589nm,

[0653] Δn represents the optical anisotropy at 20°C and 589 nm,

[0654] ε || represents the dielectric constant parallel to the director at 20°C and 1kHz,

[0655] ε ⊥ represents the dielectric constant perpendicular to the director at 20°C and 1kHz,

[0656] Δε represents the dielectric anisotropy at 20°C and 1kHz,

[0657] cl.p.,T(N,I) represents the clearing point [℃],

[0658] γ1 represents the rotational viscosity [mPa·s] measured at 20°C, determined by the rotation method in a magnetic field,

[0659] K1 is the elastic constant, the “bending” deformation at 20°C [pN],

[0660] K2 represents the elastic constant, "torsion" deformation at 20°C [pN],

[0661] K3 represents the elastic constant, "bending" deformation at 20°C [pN],

[0662] Unless otherwise explicitly stated, the term "threshold voltage" of the present invention relates to the capacitive threshold (V0). In an embodiment, as usual, the optical threshold may also be for a 10% relative contrast ratio (V 10 ) pointed out.

[0663] Reference Example 1

[0664] Liquid crystal base mixture B-1 was prepared and its general physical properties were characterized, and it had the composition and properties shown in the following table.

[0665]

[0666]

[0667] Reference Example 2

[0668] Liquid crystal base mixture B-2 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0669]

[0670]

[0671] The main mixture H-2 was prepared by mixing 99.97% of the mixture B-2 with 0.03% of the compound of the formula

[0672]

[0673] Mixture C-2 was prepared by mixing 99.95% of mixture H-2 with 0.05% of the compound of formula S-811 as described in Table F above.

[0674] Reference Example 3

[0675] Liquid crystal base mixture B-3 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0676]

[0677] Reference Example 4

[0678] Liquid crystal base mixture B-4 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0679]

[0680] Reference Example 5

[0681] Liquid crystal base mixture B-5 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0682]

[0683]

[0684] Reference Example 6

[0685] Liquid crystal host mixture B-6 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0686]

[0687] Reference Example 7

[0688] Liquid crystal base mixture B-7 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0689]

[0690]

[0691] Host mixture H-7 was prepared by mixing 98.41% of mixture B-7 with 1.59% of the compound of formula R-5011 as described in Table F above.

[0692] Reference Example 8

[0693] Liquid crystal base mixture B-8 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0694]

[0695] Reference Example 9

[0696] Liquid crystal base mixture B-9 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0697]

[0698] Prepare bulk mixture H-9 by mixing 99.97% of mixture B-9 with 0.03% of the compound of formula

[0699]

[0700] Reference Example 10

[0701] Liquid crystal base mixture B-10 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0702]

[0703]

[0704] Reference Example 11

[0705] Liquid crystal base mixture B-11 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0706]

[0707] Reference Example 12

[0708] Liquid crystal base mixture B-12 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0709]

[0710]

[0711] Reference Example 13

[0712] Liquid crystal base mixture B-13 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0713]

[0714] Reference Example 14

[0715] Liquid crystal base mixture B-14 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0716]

[0717] Reference Example 15

[0718] Liquid crystal base mixture B-15 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0719]

[0720]

[0721] Reference Example 16

[0722] Liquid crystal base mixture B-16 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0723]

[0724] Reference Example 17

[0725] Liquid crystal base mixture B-17 was prepared and characterized for its general physical properties, and had the composition and properties shown in the following table.

[0726]

[0727] Reference Example 18

[0728] The corresponding properties of each compound of Formula I-1, I-2, I-3, I-4, II-1, II-4 and II-5 were determined.

[0729] The following table shows the anisotropy measurements of the compounds.

[0730]

[0731]

[0732] Each of the compounds of Formulas I-1, I-2, I-3, I-4, II-1, II-4 and II-5 itself has sufficient solubility in the basic mixture B-1 shown in Reference Example 1 and the basic mixture B-8 shown in Reference Example 8.

[0733] For each of the compounds of formula I-1, I-2, I-3, I-4, II-1, II-4 and II-5, the stability over time for exposure in base mixtures B-1 and B-8 was studied using Suntest CPS+ from MTS-Atlas at black standard temperatures of 42° C. and 70° C. All compounds individually exhibited sufficient stability, however, the compounds of formula II-1, formula II-4 and formula II-5 individually exhibited slightly less stability compared to the performance of the corresponding compounds of formula I-1, I-2, I-3 and I-4.

[0734] Comparative Example 1

[0735] Mixture CM-1 was prepared by mixing 99.007% of mixture H-2 as described above in Reference Example 2 with 0.195% of the compound of formula I-1, 0.064% of the compound of formula

[0736]

[0737] 0.100% of the compound of formula

[0738]

[0739] and 0.634% of the following compound

[0740]

[0741] The mixture CM-1 was filled into a test cell with an antiparallel polyimide alignment layer and a cell gap of 23.7 μm. Strong residual fluorescence was visible to the naked eye.

[0742] Comparative Example 2

[0743] Mixture CM-2 was prepared by mixing 96.350% of mixture B-1 as described above in Reference Example 1 with 0.050% of the compound of formula It will be referred to as ST-1 hereinafter, 1.460% of the compound of formula I-1, 1.644% of the compound of formula I-2 and 0.496% of the compound of formula I-3.

[0744] The mixture CM-2 was filled into a test cell having an anti-parallel polyimide alignment layer and a cell gap of 11.6 μm. A relatively strong residual fluorescence was still observed.

[0745] In the following, the physical properties of the compositions and media comprising the dyes according to the invention and their suitability for use in devices for regulating energy transport are investigated.

[0746] Example 1

[0747] Mixture M-1 was prepared by mixing: 98.919% of mixture B-1 as described above in Reference Example 1 with 0.030% of compound ST-1 as shown in Comparative Example 2 above, 0.030% of the compound of formula I-1, 0.230% of the compound of formula I-2, 0.137% of the compound of formula I-4, 0.272% of the compound of formula II-1 and 0.382% of the compound of formula II-4.

[0748] Mixture M-1 was filled into a test cell with an antiparallel polyimide alignment layer and a cell gap of 23.7 μm. Only weak residual fluorescence was observed.

[0749] Example 2

[0750] Mixture M-2 was prepared by mixing: 94.905% of mixture B-1 as described above in Reference Example 1 with 0.050% of compound ST-1 as shown in Comparative Example 2 above, 0.434% of the compound of formula I-1, 0.997% of the compound of formula I-2, 0.849% of the compound of formula I-3, 1.300% of the compound of formula II-1 and 1.465% of the compound of formula II-4.

[0751] The combined dye compounds exhibit excellent solubility in host mixtures and excellent stability against heat and light.

[0752] Mixture M-2 was filled into an electrically switchable test cell with an antiparallel polyimide alignment layer, wherein the thickness of the switching layer was 25 μm. The performance for the light state and the dark state was evaluated. The measurements were performed according to standard EN410.

[0753] Determine the following values:

[0754] Transmittance τ v (Dark state): 18.4%

[0755] Transmittance τ v (Bright state): 36.7%

[0756] Chromaticity coordinate x (dark state): 0.321

[0757] Chromaticity coordinate y (dark state): 0.355

[0758] Chromaticity coordinate x (bright state): 0.321

[0759] Chromaticity coordinate y (bright state): 0.355.

[0760] The chromaticity coordinates or color coordinates are determined according to the CIE 1931 2° standard observer.

[0761] Fluorescence measurements were performed using a spectrophotometer at excitation wavelengths of 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, and 550 nm. No discernible residual fluorescence was observed in the visible spectrum.

[0762] Mixture M-2 was filled into an electrically switchable test cell with Heilmeier configuration, using an ITOS XP-40HT polarizer, with an antiparallel polyimide alignment layer and a switching layer thickness of 12 μm. The performance was evaluated for the light state and the dark state. The measurements were performed according to standard EN410.

[0763] Determine the following values:

[0764] Transmittance τ v (Dark state): 0.6%

[0765] Transmittance τ v (Bright state): 24.6%

[0766] Chromaticity coordinate x (dark state): 0.301

[0767] Chromaticity coordinate y (dark state): 0.323

[0768] Chromaticity coordinate x (bright state): 0.324

[0769] Chromaticity coordinate y (bright state): 0.354.

[0770] Mixture M-2 is well suited for use in devices which regulate the transfer of energy from an exterior space into an interior space, for example in windows.

[0771] Example 3

[0772] The following mixtures M-3-1, M-3-2, M-3-3, M-3-4 and M-3-5 were prepared by mixing the base mixture B-1 with the additional compounds according to the following table, respectively.

[0773] M-3-1 M-3-2 M-3-3 M-3-4 M-3-5 B-1 94.896％ 94.691％ 95.391％ 95.855％ 94.653％ ST-1 0.050％ 0.050％ 0.050％ 0.050％ 0.050％ I-1 0.704％ 0.752％ 0.500％ 0.550％ 0.360％ I-2 0.765％ 0.698％ 0.945％ 0.866％ 1.252％ I-3 0.919％ 0.879％ 0.840％ 0.963％ 0.734％ II-1 1.406％ 1.771％ 1.428％ 1.122％ 1.669％ II-4 1.260％ 1.159％ 0.846％ 0.594％ 1.282％

[0774] Mixtures M-3-1, M-3-2, M-3-3, M-3-4 and M-3-5 were respectively filled into electrically switchable devices with Heilmeier configuration using ITOS XP-40HT polarizers with antiparallel polyimide alignment layers and a switching layer thickness of 11.6 μm.

[0775] The performance for the light state and the dark state was evaluated. The measurements were performed according to standard EN410.

[0776]

[0777]

[0778] Fluorescence measurements were performed using a spectrophotometer at excitation wavelengths of 300 nm, 350 nm, 400 nm, 450 nm, 500 nm and 550 nm, respectively. For mixtures M-3-1, M-3-2, M-3-3, M-3-4 and M-3-5, no discernible residual fluorescence in the visible spectral range was observed.

[0779] Mixtures M-3-1, M-3-2, M-3-3, M-3-4 and M-3-5 are well suited for use in devices that regulate the transfer of energy from an exterior space into an interior space, for example in windows.

[0780] Example 4

[0781] Mixture M-4 was prepared by mixing: 94.367% of the mixture B-1 as described above in Reference Example 1 with 0.369% of the compound of formula I-1, 1.192% of the compound of formula I-2, 0.699% of the compound of formula I-4, 1.636% of the compound of formula II-1, 1.187% of the compound of formula II-4, 0.150% of the compound ST-1 as shown above in Comparative Example 2, 0.150% of the compound of formula

[0782]

[0783] and 0.250% of the compound of the formula

[0784]

[0785] The mixture M-4 was filled into a test cell with a cell gap of 23.6 μm. The stability of M-4 against light exposure over time was investigated using Suntest CPS+ from MTS-Atlas at a black standard temperature of 70° C. No color changes were observed over a period of more than 26 weeks.

[0786] Example 5

[0787] Mixture M-5 was prepared by mixing 94.667% of the mixture B-1 as described above in Reference Example 1 with 0.369% of the compound of formula I-1, 1.192% of the compound of formula I-2, 0.699% of the compound of formula I-4, 1.636% of the compound of formula II-1, 1.187% of the compound of formula II-4, 0.150% of the compound ST-1 as shown in Comparative Example 2 above, and 0.100% of the compound of formula

[0788]

[0789] The mixture M-5 was filled into a test cell with a cell gap of 23.1 μm. The stability of M-5 against light exposure over time was investigated using Suntest CPS+ from MTS-Atlas at a black standard temperature of 70° C. No color changes were observed over a period of more than 39 weeks.

[0790] Example 6

[0791] Mixture M-6 was prepared by mixing 94.767% of the mixture B-1 as described above in Reference Example 1 with 0.369% of the compound of formula I-1, 1.192% of the compound of formula I-2, 0.699% of the compound of formula I-3, 1.636% of the compound of formula II-1, 1.187% of the compound of formula II-4 and 0.150% of the compound of formula

[0792]

[0793] The mixture M-6 was filled into a test cell with a cell gap of 22.5 μm. The stability of M-6 against light exposure over time was investigated using Suntest CPS+ from MTS-Atlas at a black standard temperature of 70° C. No color changes were observed over a period of more than 26 weeks.

[0794] Examples 7 to 14

[0795] Mixtures M-7 to M-14 were prepared analogously to mixture M-2 described in Example 2, wherein instead of base mixture B-1, mixtures B-2, C-2, B-3, B-4, B-5, B-6, B-7 and H-7 described in reference examples 2 to 7 were used as main mixtures.

[0796] Mixtures M-7 to M-14 were processed and analyzed similarly to M-2 described above in Example 2. The mixtures are suitable for use in devices that regulate the transfer of energy from an exterior space into an interior space, such as windows.

[0797] Embodiment 15

[0798] Mixture M-15 was prepared by mixing 96.364% of mixture B-8 as described above in Reference Example 8 with 0.566% of the compound of formula I-1, 0.847% of the compound of formula I-4, 0.730% of the compound of formula II-1, 0.962% of the compound of formula II-4, 0.030% of compound ST-1 as shown above in Comparative Example 2, and 0.501% of the compound of formula

[0799]

[0800] The mixture M-15 was filled into a test cell with a cell gap of 23.0 μm. The stability of M-15 against light exposure over time was investigated using Suntest CPS+ from MTS-Atlas at a black standard temperature of 70° C. No color changes were observed over a period of more than 10 weeks.

[0801] Example 16

[0802] Mixture M-16 was prepared by mixing 96.359% of mixture B-8 as described above in Reference Example 8 with 0.566% of the compound of formula I-1, 0.847% of the compound of formula I-4, 0.730% of the compound of formula II-1, 0.967% of the compound of formula II-4, 0.030% of compound ST-1 as shown above in Comparative Example 2, and 0.501% of the compound of formula

[0803]

[0804] The mixture M-16 was filled into a test cell with a cell gap of 23.0 μm. The stability of M-16 against light exposure over time was investigated using Suntest CPS+ from MTS-Atlas at a black standard temperature of 70° C. No color changes were observed over a period of more than 10 weeks.

[0805] Mixture M-16 was filled into an electrically switchable device having a switching layer with a thickness of 23.0 μm. The combined dye compounds exhibited excellent solubility in the host mixture and excellent stability against heat and light and provided excellent switching contrast.

[0806] The mixture M-16 is well suited for use in devices that regulate the transfer of energy from an exterior space into an interior space, for example in windows.

[0807] Examples 17 to 25

[0808] Mixtures M-17 to M-25 were prepared analogously to the mixture M-16 described in Example 16, wherein instead of the basic mixture B-8, the mixtures B-9, B-10, B-11, B-12, B-13, B-14, B-15, B-16 and B-17 described in reference examples 9 to 17 were used as the main mixtures.

[0809] The mixture is suitable for use in devices that regulate the transfer of energy from an exterior space into an interior space, such as windows.

[0810] Embodiment 26

[0811] Mixture M-26 was prepared by mixing: 95.596% of mixture B-1 as described above in Reference Example 1 with 0.050% of compound ST-1 as shown above in Comparative Example 2, 0.450% of the compound of formula I-1, 0.924% of the compound of formula I-2, 0.780% of the compound of formula I-3, 1.550% of the compound of formula I-4 and 0.650% of compound (182)

[0812]

[0813] The mixture is suitable for use in devices that regulate the transfer of energy from an exterior space into an interior space, such as windows.

[0814] Embodiment 27

[0815] Mixture M-27 was prepared by mixing 95.646% of the mixture B-1 as described above in Reference Example 1 with 0.450% of the compound of formula I-1, 0.924% of the compound of formula I-2, 0.780% of the compound of formula I-3, 1.550% of the compound of formula I-4 and 0.650% of the compound (182) as shown in Example 26 above.

[0816] The mixture is suitable for use in devices that regulate the transfer of energy from an exterior space into an interior space, such as windows.

[0817] Embodiment 28

[0818] Mixture M-28 was prepared by mixing: 89.45% of the mixture B-1 as described in Reference Example 1 above with 0.05% of the compound ST-1 as shown in Comparative Example 2 above, 1.00% of the compound of formula I-1, 2.20% of the compound of formula I-2, 2.20% of the compound of formula I-3, 2.00% of the compound of formula II-4, 1.30% of the compound of formula II-5 and 1.80% of the compound (182) as shown in Example 26 above.

[0819] The mixture is suitable for use in devices that regulate the transfer of energy from an exterior space into an interior space, such as windows.

[0820] Embodiment 29

[0821] Mixture M-29 was prepared by mixing: 89.45% of mixture B-8 as described above in Reference Example 8 with 0.05% of compound ST-1 as shown in Comparative Example 2 above, 1.00% of the compound of formula I-1, 2.20% of the compound of formula I-2, 2.20% of the compound of formula I-3, 2.00% of the compound of formula II-4, 1.30% of the compound of formula II-5 and 1.80% of compound (182) as shown in Example 26 above.

[0822] The mixture is suitable for use in devices that regulate the transfer of energy from an exterior space into an interior space, such as windows.

[0823] Embodiment 30

[0824] Mixture M-30 was prepared by mixing: 89.268% of the mixture B-1 as described in Reference Example 1 above with 0.100% of the compound ST-1 as shown in Comparative Example 2 above, 0.382% of the compound of formula R-5011 as described in Table F above, 0.950% of the compound of formula I-1, 1.900% of the compound of formula I-2, 2.300% of the compound of formula I-3, 1.800% of the compound of formula II-1, 2.200% of the compound of formula II-4 and 1.100% of the compound of formula II-5.

[0825] The mixture is suitable for use in devices that regulate the transfer of energy from an exterior space into an interior space, such as windows.

Claims

1. A liquid crystal medium comprising a composition and one or more mesogenic compounds, wherein the composition comprises two or more compounds selected from the group consisting of compounds of formula I-1, I-2, I-3 and I-4 and two or more compounds selected from compounds of formula II-1, II-2, II-3, II-4 and II-5, 2 . The liquid-crystalline medium according to claim 1 , wherein the composition comprises at least one violet dye, at least one blue dye, at least one yellow dye, at least one red dye and at least one near-infrared dye.

3. A liquid-crystalline medium according to claim 1, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae CY, PY and AC in express express R 1 , R 2 , R AC1 , R AC2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, Z x , Z y , Z AC each independently represents -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, L 1 , L 2 , L 3 , L 4 Each independently represents F, Cl, CN, OCF3, CF3, CH3, CH2F, CHF2, a is 1 or 2, b is 0 or 1, c is 0, 1, or 2, d is 0 or 1.

4. A liquid-crystalline medium according to claim 3, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae IIA to VIII in Each independently expresses R 20 represent, identically or differently, halogenated or unsubstituted alkyl or alkoxy radicals having 1 to 15 C atoms, wherein In addition, one or more CH2 groups in these groups may be independently connected to each other via -C≡C-, -CF2O-, -CH=CH-, -O-, -CO-O- or -O-CO-, X 20 represent, identically or differently, F, Cl, CN, SF5, SCN, NCS, a halogenated alkyl group, a halogenated alkenyl group, a halogenated alkoxy group or a halogenated alkenyloxy group each having 1 to 6 C atoms, and Y 20 , Y 21 , Y 22 , Y 23 , Y 24 each identically or differently represents H or F, Z 20 represents -C2H4-, -(CH2)4-, -CH=CH-, -CF=CF-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH2O-, -OCH2-, -COO- or -OCF2-, and in Formula V and Formula VI also represents a single bond, and in Formula V and Formula VIII also represents -CF2O-, r represents 0 or 1, and s represents 0 or 1.

5. A liquid-crystalline medium according to claim 3 or 4, wherein the medium additionally comprises one or more compounds selected from the group of compounds of the formula D, K and O in R 5 , R 6 , R O1 and R O2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, express express express and express Z O1 represents -CH2CH2-, -CF2CF2-, -C=C- or a single bond, Z O2 represents CH2O, -C(O)O-, -CH2CH2-, -CF2CF2- or a single bond, o is 1 or 2, and e is 1 or 2.

6. A liquid-crystalline medium according to claim 3 or 4, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae O3 to O5 Where R O1 and R O2 represents, identically or differently, a straight-chain alkyl radical having 1 to 6 C atoms or a straight-chain alkenyl radical having 2 to 6 C atoms.

7. A liquid-crystalline medium according to claim 3 or 4, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae DK1 to DK12: Here, alkyl and alkyl* each independently of one another represent a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl radical having 2 to 6 C atoms.

8. A device for regulating the transfer of energy from an external space into an internal space, wherein the device contains a switching layer comprising a liquid-crystalline medium according to any one of claims 1 to 7.

9. A window comprising a device according to claim 8.

10. Use of a liquid-crystalline medium according to any one of claims 1 to 7 in architectural windows or vehicle sunroofs.

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