Compounds and liquid crystalline media

Abstract

The invention relates to compounds of formula (I), and preferably to liquid-crystalline media having a nematic phase and negative dielectric anisotropy, comprising a) one or more compounds of formula (I) and b) one or more compounds selected from the group of compounds of formulae (II) and (III) wherein the parameters have the meanings given in claim 1, to the use thereof in electro-optical displays, especially in active matrix displays based on the VA, ECB, PALC, FFS or IPS effect, to displays of this type comprising a liquid-crystalline medium of this type, and to the use of compounds of formula (I) for stabilizing a liquid-crystalline medium comprising one or more compounds of formula (II) and one or more compounds selected from the group of compounds of formulae (III-1) to (III-4) and B.

Description

[0001] The present application relates to novel compounds, in particular novel compounds for use in liquid-crystalline media, but also to the use of these liquid-crystalline media in liquid-crystalline displays and to these liquid-crystalline displays, in particular to liquid-crystalline displays with dielectrically negative liquid crystals using the ECB (electrically controlled birefringence) effect in homeotropic initial alignment. The liquid-crystalline media according to the present application are characterized by particularly short response times in displays according to the present application, while at the same time having a high voltage holding ratio (VHR or also just HR).

[0002] The principle of the electrically controlled birefringence, ECB effect, or DAP (deformation of aligned phase) effect was first described in 1971 (M. F. Schieckel and K. Fahrenschon, "Deformation of nematic liquid crystals with vertical orientation in electrical fields", Appl. Phys. Lett. 19 (1971), 3912). This was followed by the papers of J. F. Kahn (Appl. Phys. Lett. 20 (1972), 1193) and G. Labrunie and J. Robert (J. Appl. Phys. 44 (1973), 4869).

[0003] The papers of J. Robert and F. Clerc (SID 80 Digest Techn. Papers (1980), 30), J. Duchene (Displays 7 (1986), 3) and H. Schad (SID 82 Digest Techn. Papers (1982), 244) have shown that the liquid-crystalline phase must have a high value of the ratio of the elastic constants K3 / K1, a high value of the optical anisotropy Δn and a dielectric anisotropy value of Δε ≤ -0.5 in order to be suitable for high-information display elements based on the ECB effect. The electro-optical display elements based on the ECB effect have a homeotropic fringe alignment (VA technology = vertical alignment, or also VAN = vertical alignment nematic). Dielectrically negative liquid-crystalline media can also be used in displays using the so-called IPS (in-plane switching) effect.

[0004] The industrial use of this effect in electro-optical display elements requires LC phases which must satisfy a multiplicity of requirements. Of particular importance here are the chemical resistance to humidity, air and physical influences such as heat, radiation in the infrared, visible and ultraviolet regions and direct and alternating electric fields.

[0005] Furthermore, it is necessary for the LC phases which can be used industrially to have a liquid-crystalline mesophase in a suitable temperature range and a low viscosity.

[0006] The series of compounds with mesophase of liquid crystals published to date do not comprise a single compound which meets all these requirements. Therefore, mixtures of 2 to 25, preferably 3 to 18, compounds are generally prepared in order to obtain a substance which can be used as an LC phase.

[0007] Matrix liquid crystal displays (MLC displays) are known. Non-linear elements which can be used for the independent switching of individual pixels are, for example, active elements (i.e. transistors). The term "active matrix" is then used, wherein generally thin film transistors (TFTs) are used, which are usually arranged on a glass plate as substrate.

[0008] A distinction is made between two technologies: TFTs comprising compound semiconductors (for example CdSe) or TFTs based on polycrystalline and especially amorphous silicon. The latter technology currently has the greatest commercial importance worldwide.

[0009] The TFT matrix is arranged on the inner side of one glass plate of the display, while the other glass plate carries a transparent counter electrode on its inner side. The TFTs are very small compared to the size of the pixel electrodes and have virtually no adverse effect on the image. The technology can also be extended to full-color displays, wherein a mosaic of red, green and blue color filters is arranged in such a way that the filter elements are relative to each switchable pixel.

[0010] The TFT displays which are used most to date are generally operated in transmission with crossed polarizers and are backlit. For TV applications, IPS cells or ECB (or VAN) cells are used, whereas monitors usually use IPS cells or TN (twisted nematic) cells, and notebook, laptop and mobile applications usually use TN cells.

[0011] The term MLC display here encompasses any matrix display with integrated non-linear elements, i.e. in addition to active matrices, also displays with passive elements, for example varistors or diodes (MIM = metal-insulator-metal).

[0012] This type of MLC display is particularly suitable for TV applications, monitors and notebooks, or for displays with a high information density, for example in automotive construction or aircraft construction. Apart from problems with the angle dependence of the contrast and the response time, MLC displays also exhibit problems due to the insufficiently high specific resistance of the liquid crystal mixture [TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K., TAJIMA, E., WATANABE, H., SHIMIZU, H., Proc. Eurodisplay 84, Sept. 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, pp. 141 ff., Paris; STROMER, M., Proc. Eurodisplay 84, Sept. 1984: Design of Thin Film Transistors for Matrix Addressing of Television Liquid Crystal Displays, pp. 145 ff., Paris]. With decreasing resistance, the contrast of the MLC display deteriorates. Due to interactions with the inner surfaces of the display, the specific resistance of the liquid crystal mixture usually decreases over the lifetime of the MLC display, so that a high (initial) resistance is very important for a display which must have an acceptable resistance value after long-term operation.

[0013] In addition to IPS displays (for example: Yeo, S. D., Paper 15.3: "An LC Display for the TV Application", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Vol. II, pp. 758 and 759) and the long-known TN displays, displays using the ECB effect, so-called VAN (vertically aligned nematic) displays, have been recognized as one of the three newer types of liquid crystal displays which are currently of particular importance, especially for television applications.

[0014] The most important designs that can be mentioned here are: MVA (multi-domain vertical alignment type, e.g. Yoshide, H. et al., Paper 3.1 : "MVA LCD for Notebook or Mobile PCs... ", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Part I, pp. 6-9, and Liu, C. T. et al., Paper 15.1 : "A 46-inch TFT-LCD HDTV Technology... ", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Part II, pp. 750-753), PVA (patterned vertical alignment type), e.g. Kim, Sang Soo, Paper 15.4: "Super PVA Sets New State-of-the-Art for LCD-TV", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Part II, pp. 760-763) and ASV (advanced super view, e.g. Shigeta, Mitzuhiro and Fukuoka, Hirofumi, Paper 15.2: "Development of High Quality LCD TV", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Part II, pp. 754-757).

[0015] In general terms, the technology is compared in, for example, Souk, Jun, SID Seminar 2004, Seminar M-6: "Recent Advances in LCD Technology", Seminar Lecture Notes, M-6 / 1 to M-6 / 26, and Miller, Ian, SID Seminar 2004, Seminar M-7: "LCD-Television", Seminar Lecture Notes, M-7 / 1 to M-7 / 32. Although the response time of modern ECB displays has been improved significantly by an addressing method of overdrive, for example: Kim, Hyeon Kyeong et al., Paper 9.1 : "A 57-in. Wide UXGA TFT-LCD for HDTV Application", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Part I, pages 106 to 109, the implementation of the video-compatible response time, especially in the case of grey level switching, is still a problem which has not been solved to a satisfactory extent.

[0016] As in the case of ASV displays, ECB displays use liquid-crystalline media having a negative dielectric anisotropy (Δε), whereas TN and hitherto all conventional IPS displays use liquid-crystalline media having a positive dielectric anisotropy.

[0017] In this type of liquid-crystalline display, the liquid crystal serves as an electrical medium, the optical properties of which change reversibly upon application of a voltage.

[0018] Since the operating voltages in displays in general, i.e. also in displays according to these mentioned effects, should be as low as possible, liquid-crystalline media which are usually composed predominantly of liquid-crystalline compounds having dielectric anisotropies of the same sign and having the highest possible dielectric anisotropy values are used. In general, at most a relatively small proportion of neutral compounds is used, and if possible no compounds having a dielectric anisotropy sign opposite to the medium are used. In the case of liquid-crystalline media having a negative dielectric anisotropy for ECB displays, therefore predominantly compounds having a negative dielectric anisotropy are employed. The liquid-crystalline media used are generally composed predominantly and often even essentially of liquid-crystalline compounds having a negative dielectric anisotropy.

[0019] In the media used according to the application, at most a significant amount of dielectrically neutral liquid-crystalline compounds is generally used and usually only very small amounts of dielectrically positive compounds or even no dielectrically positive compounds are used, since in general the liquid-crystalline displays are intended to have the lowest possible addressing voltage.

[0020] The known liquid-crystalline media are not sufficiently stable for many practical applications in liquid-crystalline displays. In particular, their stability against irradiation with UV light and even with conventional backlighting leads to impairments, in particular impairments of the electrical properties. Thus, for example, the electrical conductivity increases significantly.

[0021] The use of so-called "hindered amine light stabilizers", shortly HALS, has already been suggested as a stabilization for liquid-crystalline mixtures.

[0022] For example, it is suggested in WO 2009 / 129911 A1 and WO 2012 / 076105 A1 to use small amounts of 770, as stabilizer, nematic liquid-crystalline mixtures having a negative dielectric anisotropy of the formula

[0023]

[0024] However, the corresponding liquid-crystalline mixtures do not have sufficient properties with respect to some practical applications. In particular, they are not sufficiently stable against irradiation with typical CCFLs (cold cathode fluorescent lamps) and in particular with typical modern LED (light emitting diode) backlights.

[0025] For example, similar liquid-crystalline mixtures are also known from EP 2 182 046 A1, WO 2008 / 009417 A1, WO 2009 / 021671 A1 and WO 2009 / 1 15886 A1. However, the use of a stabilizer is not indicated in these documents.

[0026] According to the disclosure of these documents, these liquid-crystalline mixtures can optionally also comprise various stabilizers, for example phenols and sterically hindered amines (hindered amine light stabilizers, shortly HALS). However, these liquid-crystalline mixtures are characterized by a relatively high threshold voltage and at most mediocre stability. In particular, their voltage retention decreases after exposure. Furthermore, the fading of the light yellow color is often increased.

[0027] For example, the use of various stabilizers in liquid-crystalline media is described in JP (S) 55-023169 (A), JP (H) 05-1 17234 (A), WO 02 / 18515 A1 and JP (H) 09-291282 (A).

[0028] In particular, EP 2 993 216 A1 suggests the following compound for the stabilization of dielectrically positive liquid-crystalline media

[0029]

[0030] WO 2009 / 129911 A1 proposes, in addition to various other compounds as second stabilizers and in addition to the nitrogen heterocycles, the following compounds for the stabilization of dielectrically negative liquid-crystalline media

[0031]

[0032] EP 2 514 800 A2 proposes the use of the following compounds for the purpose of stabilization of liquid-crystalline media

[0033]

[0034]

[0035] wherein R 11 In addition to other meanings, can also be O. or OH, instead of H. However, the chemical stability of these compounds in terms of hydrolysis and, in particular, their solubility in liquid-crystalline media in most cases is insufficient for practical applications.

[0036] WO 2016 / 146245 A1 proposes the following compounds for the purpose of stabilization in liquid-crystalline media.

[0037]

[0038] The above-mentioned compounds and the following compounds for the purpose of stabilization in liquid-crystalline media are also proposed in DE 2016 005 083 A1

[0039]

[0040] However, the chemical stability, in particular in terms of hydrolysis, and, in particular, the solubility in liquid-crystalline media in most cases is insufficient for practical applications.

[0041] The unpublished application DE 10 2016 009485.0 proposes the following ether-linked compounds for use as stabilizers for liquid-crystalline mixtures.

[0042]

[0043]

[0044] The prior-art liquid-crystalline media having correspondingly low addressing voltages have a relatively low electrical resistance value or low VHR and often lead to undesired flicker and / or insufficient transmission in displays. Furthermore, they are insufficiently stable to heat / UV exposure, at least if they have a correspondingly high polarity, which is necessary for low addressing voltages.

[0045] On the other hand, the addressing voltage of the prior art displays with high VHR is usually too high, especially for displays not directly or not permanently connected to a mains supply network, for example for displays for mobile applications.

[0046] Furthermore, the phase range of the liquid crystal mixture must be sufficiently wide for the intended application of the display. Thus, the low temperature storage at -30°C in a cell and preferably in bulk should be 240 hours or more.

[0047] The response time of the liquid crystal medium in the display must be improved, i.e. reduced. This is particularly important for displays for television or multimedia applications. In order to improve the response time, it has been repeatedly proposed in the past to optimize the rotational viscosity (γ1) of the liquid crystal medium, i.e. to achieve a medium with the lowest possible rotational viscosity. However, the results achieved here are not sufficient for many applications and thus make it desirable to find further optimization methods.

[0048] The sufficient stability of the medium against extreme loads, especially against UV exposure and heat, is of very particular importance. This is particularly difficult for simultaneous optimization of the rotational viscosity. This can be important in the case of applications in displays in mobile devices, for example mobile telephones, since, especially in these devices, a relatively low addressing frequency is preferably used.

[0049] The disadvantages of the MLC displays disclosed to date are due to their comparatively low contrast, the relatively high viewing angle dependence and the difficulties in the generation of grey levels in these displays, as well as their insufficient VHR and their insufficient lifetime.

[0050] Therefore, there is still a great need for MLC displays with very high specific resistance, while at the same time having a large operating temperature range, short response times and low threshold voltages, by means of which various grey levels can be generated, especially with a good and stable VHR.

[0051] It is the object of the present application to provide MLC displays which, based on the ECB, IPS or FFS (fringe field effect) effect, as described in Lee, S. H., Lee, S. L. and Kim, H. Y. "Electro-optical characteristics and switching principle of nematic liquid crystal cell controlled by fringe-field switching", Appl. Phys. Letts., Vol. 73, No. 20, pp. 2881-2883 (1998), do not have the disadvantages indicated above, or only to a small extent, and at the same time have a very high specific resistance value, not only for monitor and TV applications, but also for mobile telephones and navigation systems. In particular for mobile telephones and navigation systems it must be ensured that they also work at very high and very low temperatures.

[0052] Surprisingly, it has been found that when using nematic liquid-crystalline mixtures in these display elements, which comprise at least one compound of the formula I and in each case at least one compound of the formula II, preferably a compound of the subformula II-1, and / or at least one compound selected from the group of the compounds of the formulae III-1 to III-4, preferably the compound of the formula III-2 and / or the compound of B, it is possible to achieve liquid-crystalline displays, in particular in FFS displays, which have a low threshold voltage and a short response time and at the same time a sufficiently wide nematic phase, an advantageously relatively low birefringence (Δn), a good stability against decomposition by heat and by UV exposure, a good solubility and a stable and high VHR.

[0053] Media of this type can be used in particular in electro-optical displays with active matrix addressing based on the ECB effect and in IPS displays and in FFS displays.

[0054] The present application therefore relates to liquid-crystalline media based on mixtures of polar compounds, which comprise at least one compound of the formula I and at least one compound comprising one or more compounds of the formula II and preferably additionally one or more compounds selected from the group of the compounds of the formulae III-1 to III-4 and / or the compound of the formula B.

[0055] The mixtures according to the application exhibit a very wide nematic phase range with a clearing point of > 70°C, a very advantageous value of the threshold of the capacitance, a value of the specific resistance which is relatively high and at the same time a good low-temperature stability at -20°C and -30°C, and a very low rotational viscosity. The mixtures according to the application are further characterised by a very good ratio of the clearing point and the rotational viscosity and by a high negative dielectric anisotropy.

[0056] It has surprisingly been found that liquid-crystalline media having a suitably high Δε, a suitable phase range and a Δn can be realized which do not have the disadvantages of the prior art materials or at least only to a significantly reduced extent.

[0057] Here, it has surprisingly been found that the compounds of the formula I even in the case of use alone without additional thermal stabilizers lead to a significant, in many cases sufficient stabilization of the liquid-crystalline mixture against UV exposure and against heat. This is in particular the case in most cases in which the parameter p in the compounds of the formula I used denotes 2 and n*p denotes 4 or 6. In one embodiment of the present application, the compounds of the formula I in which p denotes 2 and n denotes 3 or 4 are therefore particularly preferred, and the use of exactly these compounds in the liquid-crystalline mixtures according to the present application is also particularly preferred. Also preferred are the compounds of the formula I in which the group -Z 11 -S 11 -Z 12 denotes an omega-dioxyalkylene radical, i.e. -O-S 11 -O-.

[0058] However, sufficient stabilization of the liquid-crystalline mixture against UV exposure and against heat can also be achieved in the case of the presence of one or more further compounds, preferably phenolic stabilizers, in the liquid-crystalline mixture in addition to the one or more compounds of the formula I. These further compounds are suitable as thermal stabilizers.

[0059] The present application therefore relates to the compounds of the formula I and to liquid-crystalline media having a nematic phase and a negative dielectric anisotropy, which comprise

[0060] a) one or more compounds of the formula I, preferably in a concentration of 1 ppm to 2500 ppm, preferably to 2000 ppm, preferably to 1500 ppm, particularly preferably to 1000 ppm, preferably in the range from 1 ppm to 500 ppm, particularly preferably in the range from 1 ppm to 250 ppm,

[0061]

[0062] wherein

[0063] R 11 in each occurrence independently of one another denote H, F, a straight-chain or branched alkyl chain having 1 -20 C atoms, wherein one -CH2- group or, if present, a plurality of -CH2- groups can be replaced by -O- or -C(=O)-, but no two adjacent -CH2- groups are replaced by -O-, and one or, if present, a plurality of -CH2- groups can be replaced by -CH=CH- or -C≡C-, and wherein one H atom or a plurality of H atoms can be replaced by F, OR13 N(R 13 )(R 14 ) or R 15 instead,

[0064] R 11 preferably denotes H or alkyl, particularly preferably alkyl, very particularly preferably n-alkyl, and very particularly preferably n-butyl,

[0065] R 12 each occurrence independently of the other denotes a linear or branched alkyl chain having 1 to 20 C atoms, wherein one -CH2- group or a plurality of -CH2- groups can be replaced by -O- or -C(=O)-, but no two adjacent -CH2- groups are replaced by -O-, a hydrocarbyl comprising a cycloalkyl or alkylcycloalkyl unit, and wherein one -CH2- group or a plurality of -CH2- groups can be replaced by -O- or -C(=O)-, but no two adjacent -CH2- groups are replaced by -O-, and wherein one H atom or a plurality of H atoms can be replaced by F, OR 13 N(R 13 )(R 14 ) or R 15 instead, or an aromatic or heteroaromatic hydrocarbyl, wherein one H atom or a plurality of H atoms can be replaced by F, OR 13 N(R 13 )(R 14 ) or R 15 instead,

[0066] R 12 preferably denotes H, unbranched alkyl or branched alkyl, particularly preferably H or unbranched alkyl,

[0067] R 13 each occurrence independently of the other denotes a linear or branched alkyl or acyl group having 1 to 10 C atoms, preferably n-alkyl, or an aromatic hydrocarbyl or carboxylic acid group having 6 to 12 C atoms,

[0068] R 14 each occurrence independently of the other denotes a linear or branched alkyl or acyl group having 1 to 10 C atoms, preferably n-alkyl, or an aromatic hydrocarbyl or carboxylic acid group having 6 to 12 C atoms,

[0069] R 15 each occurrence independently of the other denotes a linear or branched alkyl having 1 to 10 C atoms, wherein one -CH2- group or a plurality of -CH2- groups can be replaced by -O- or -C(=O)-, but no two adjacent -CH2- groups are replaced by -O-,

[0070] S 11 and S 12in each occurrence independently of one another, alkylene having 1 to 20 C atoms which is branched, or preferably straight-chain, preferably having 1 to 20 C atoms, preferably having 1 to 10 C atoms, particularly preferably having 1 to 8 C atoms, -(CH2-)n n where one -CH2- group or, if present, a plurality of -CH2- groups can be replaced by -O- or -C(=O)-, but no two adjacent -CH2- groups are replaced by -O-, and one or, if present, a plurality of -CH2- groups can be replaced by -CH=CH- or -C≡C- and where one H atom or a plurality of H atoms can be replaced by F, OR 13 , N(R 13 )(R 14 ) or R 15 , or denotes a single bond, X 11 denotes C,

[0071] Y 11 to Y 14 each, independently of one another, denote methyl or ethyl, particularly preferably both denote methyl or ethyl and very particularly preferably methyl,

[0072] Z 11 to Z 14 in each occurrence independently of one another, denote -O-, -(C=O)-, -O-(C=O)-, -(C=O)-O-, -O-(C=O)-O-, -(N-R 13 )-, -N-R 13 -(C=O)- or, if S 11 is a single bond, denotes a single bond, but Z 11 and Z 12 do not both simultaneously denote -O-, and, however, if S 12 is a single bond, Z 13 and Z 14 do not both simultaneously denote -O-, and, however, if -X 11 [-R 11 ] o is a single bond, Z 12 and Z 13 do not both simultaneously denote -O-,

[0073] Z 11 preferably denotes -O-,

[0074] Z 13 preferably denotes a single bond,

[0075] n*p denotes an integer from 3 to 10, preferably to 8,

[0076] p denotes 1 or 2,

[0077] o denotes (3-p),

[0078] in case p = 1,

[0079] n denotes 3, 4, 5, 6 or 8, particularly preferably 4, 6, or 8, very particularly preferably 4 or 6, and

[0080] m denotes (10-n), and

[0081] in case p = 2,

[0082] n denotes an integer from 2 to 4, preferably 2 or 3, particularly preferably 3, and

[0083] m denotes (4-n), and

[0084] denotes an organic group having (m+n) bonding sites, preferably an alkanediyl, alkanetriyl or alkanetetrayl unit having 4 bonding sites, preferably having 1 to 30 C atoms, wherein, in addition to the m groups R 12 present in the molecule, but independently thereof, one further H atom can be replaced by R 12 or a plurality of further H atoms can be replaced by R 12 , preferably an alkanetetrayl unit having one or two valences at each terminal C atom, wherein one -CH2- group or a plurality of -CH2- groups can be replaced by -O- or -(C=0)- in such a way that two -O- atoms are not directly bonded to one another, or a substituted or unsubstituted aromatic or heteroaromatic hydrocarbon group having up to 10 valences, wherein, in addition to the m groups R 12 present in the molecule, but independently thereof, one further H atom can be replaced by R 12 or a plurality of further H atoms can be replaced by R 12 ,

[0085] and in case p = 1, -X 11 [-R 11 ] o - alternatively can also denote a single bond, and

[0086] b) one or more compounds selected from the group of compounds of the formulae II and III, preferably of dielectric positive nature, preferably having a dielectric anisotropy of 3 or more in each case:

[0087]

[0088] wherein

[0089] R 2H, an unfluorinated or fluorinated alkyl or unfluorinated or fluorinated alkoxy group having 1 to 17 C atoms, or an unfluorinated or fluorinated alkenyl, unfluorinated or fluorinated alkenyloxy or unfluorinated or fluorinated alkoxyalkyl group having 2 to 15 C atoms, in which one or more CH2-groups can be replaced by instead, an alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy group having 1 to 7 carbon atoms, an alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl group having 2 to 7 carbon atoms, and preferably an alkyl or alkenyl group,

[0090] independently of one another in each occurrence represent

[0091]

[0092]

[0093] wherein R L independently of one another in each occurrence represent H or an alkyl group having 1 to 6 C atoms, or

[0094]

[0095] preferably

[0096]

[0097]

[0098] more preferably

[0099]

[0100] L 21 and L 22 independently of one another represent H or F, preferably L 21 represents F,

[0101] X 2 represents halogen, halogenated alkyl having 1-3 C atoms, or alkoxy or halogenated alkenyl or alkenyloxy having 2 or 3 C atoms, preferably F, CI, -OCF3, -O-CH2CF3, -O-CH=CH2, -O-CH=CF2or -CF3, very preferably F, CI, -O-CH=CF2or -OCF3, m represents 0, 1, 2 or 3, preferably 1 or 2, and particularly preferably 1,

[0102] R 3 has the meaning given for R 2one or more of the meanings given, i.e. H, unfluorinated or fluorinated alkyl with 1 to 17 C atoms or unfluorinated or fluorinated alkoxy with 1 to 17 C atoms, or unfluorinated or fluorinated alkenyl with 2 to 15 C atoms, unfluorinated or fluorinated alkenyloxy or unfluorinated or fluorinated alkoxyalkyl, in which one or more CH2-groups can be replaced by one or more of the meanings given, i.e. H, unfluorinated or fluorinated alkyl with 1 to 17 C atoms or unfluorinated or fluorinated alkoxy with 1 to 17 C atoms, or unfluorinated or fluorinated alkenyl with 2 to 15 C atoms, unfluorinated or fluorinated alkenyloxy or unfluorinated or fluorinated alkoxyalkyl, in which one or more CH2-groups can be replaced by

[0103] independently of one another in each occurrence have one of the meanings given above for and preferably is

[0104]

[0105] more preferably

[0106]

[0107] L 31 and L 32 independently of one another denote H or F, preferably L 31 denotes F,

[0108] X 3 denotes halogen, halogenated alkyl or alkoxy with 1 to 3 C atoms or halogenated alkenyl or alkenyloxy with 2 or 3 C atoms, preferably F, CI, -OCF3, -OCHF2, -O-CH2CF3, -O-CH=CF2, -O-CH=CH2or -CF3, very preferably F, CI, -O-CH=CF2, -OCHF2or -OCF3,

[0109] Z 3 denotes -CH2CH2-, -CF2CF2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CH2O- or a single bond, preferably -CH2CH2-, -COO-, trans-CH=CH- or a single bond and very preferably -COO-, trans-CH=CH- or a single bond, and

[0110] n denotes 0, 1, 2 or 3, preferably 1, 2 or 3 and particularly preferably 1, and

[0111] c) optionally one or more compounds selected from the group of compounds of the formulae IV and V, preferably dielectrically neutral:

[0112]

[0113] in which

[0114] R 41 and R 42 independently of one another have the meanings given above for R 2 in formula II, preferably R 41 denotes alkyl and R 42 denotes alkyl or alkoxy or R 41 denotes alkenyl and R 42 denotes alkyl,

[0115] independently of one another and, if occur twice, these also independently of one another have one of the meanings given above for and preferably denote

[0116]

[0117]

[0118] preferably one or more of denote

[0119] Z 41 and Z 42 independently of one another and, if Z 41 occur twice, these also independently of one another denote -CH2CH2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CH2O-, -CF2O-, -C≡C- or a single bond, preferably one or more of them denote a single bond, and

[0120] p denotes 0, 1 or 2, preferably 0 or 1,

[0121] R 51 and R 52 independently of one another have one of the meanings given above for R 41 and R 42 and preferably denote alkyl having 1 to 7 C atoms, preferably n-alkyl, particularly preferably n-alkyl having 1 to 5 C atoms, alkoxy having 1 to 7 C atoms, preferably n-alkoxy, particularly preferably n-alkoxy having 2 to 5 C atoms, alkoxyalkyl having 2 to 7 C atoms, preferably having 2 to 4 C atoms, alkenyl or alkenyloxy, preferably alkenyloxy,

[0122] to if present, each independently of one another have one of the meanings given above for and preferably denote

[0123]

[0124]

[0125] preferably

[0126]

[0127] preferably

[0128] denotes

[0129] and, if present

[0130] preferably denotes

[0131] Z 51 to Z 53 each, independently of one another, denotes -CH2-CH2-, CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, preferably -CH2-CH2-, -CH2-O- or a single bond, and particularly preferably a single bond,

[0132] i and j each, independently of one another, denote 0 or 1,

[0133] (i + j) preferably denotes 0, 1 or 2, more preferably 0 or 1, and most preferably 1,

[0134] d) optionally, alternatively or in addition, one or more compounds selected from compounds of the formulae VI to IX, preferably of dielectric negative:

[0135]

[0136] wherein

[0137] R 61 , R 62 , R 71 , R 72 , R 81 and R 82 , independently of one another, have one of the meanings given above for R 41 and R 42 , preferably

[0138] R 61 denotes unsubstituted alkyl having 1 to 7 C atoms, preferably straight-chain alkyl, more preferably n-alkyl, most preferably propyl or pentyl, unsubstituted alkenyl having 2 to 7 C atoms, preferably straight-chain alkenyl, particularly preferably having 2 to 5 C atoms, unsubstituted alkoxy having 1 to 6 C atoms, or unsubstituted alkenyloxy having 2 to 6 C atoms,

[0139] R62 This refers to an unsubstituted alkyl group having 1 to 7 carbon atoms, an unsubstituted alkoxy group having 1 to 6 carbon atoms, or an unsubstituted olefinic group having 2 to 6 carbon atoms, and

[0140] l represents 0 or 1.

[0141] R 71 This indicates an unsubstituted alkyl group having 1 to 7 carbon atoms, preferably a straight-chain alkyl group, more preferably a n-alkyl group, and most preferably propyl or pentyl, or an unsubstituted alkenyl group having 2 to 7 carbon atoms, preferably a straight-chain alkenyl group, and particularly preferably having 2 to 5 carbon atoms.

[0142] R 72 This indicates an unsubstituted alkyl group having 1 to 7 carbon atoms, preferably 2 to 5 carbon atoms; an unsubstituted alkoxy group having 1 to 6 carbon atoms, preferably 1, 2, 3, or 4 carbon atoms; or an unsubstituted olefinic group having 2 to 6 carbon atoms, preferably 2, 3, or 4 carbon atoms.

[0143] R 81 This indicates an unsubstituted alkyl group having 1 to 7 carbon atoms, preferably a straight-chain alkyl group, more preferably a n-alkyl group, and most preferably propyl or pentyl, or an unsubstituted alkenyl group having 2 to 7 carbon atoms, preferably a straight-chain alkenyl group, and particularly preferably having 2 to 5 carbon atoms.

[0144] R 82 This indicates an unsubstituted alkyl group having 1 to 7 carbon atoms, preferably 2 to 5 carbon atoms; an unsubstituted alkoxy group having 1 to 6 carbon atoms, preferably 1, 2, 3, or 4 carbon atoms; or an unsubstituted olefinic group having 2 to 6 carbon atoms, preferably 2, 3, or 4 carbon atoms.

[0145] express

[0146]

[0147] express

[0148]

[0149] Preferred

[0150]

[0151] More

[0152]

[0153] Z 8represents -(C=0)-0-, -CH2-0-, -CF2-0- or -CH2-CH2-, preferably -(C=0)-0- or -CH2-0-, and

[0154] o represents 0 or 1,

[0155] R 91 and R 92 each independently have the meaning given above for R 72 ,

[0156] R 91 preferably represents an alkyl group having 2 to 5 carbon atoms, preferably having 3 to 5 carbon atoms,

[0157] R 92 preferably represents an alkyl group having 2 to 5 carbon atoms, preferably having 3 to 5 carbon atoms,

[0158] represents

[0159] p and q each independently represent 0 or 1, and

[0160] (p+q) preferably represents 0 or 1, and in the case where represents alternatively, preferably p=q=1,

[0161] e) optionally, one or more compounds of formula IN having a high dielectric constant perpendicular to the director and parallel to the director, preferably in a concentration in the range of 1 % to 60%, more preferably in the range of 5% to 40%, particularly preferably in the range of 8% to 35%,

[0162]

[0163] wherein

[0164] represents

[0165]

[0166] represents

[0167]

[0168]

[0169] n represents 0 or 1,

[0170] R 11 and R 12independently of one another alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 C atoms, and preferably alkyl, alkoxy, alkenyl or alkenyloxy, most preferably alkyl, alkoxy or alkenyloxy, and R 11 alternatively R 1 and R 12 alternatively X 1 ,

[0171] R 1 alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7 C atoms, in which one -CH2- group can be replaced by cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, preferably by cyclopropylene or 1,3-cyclopentylene, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 C atoms, in which one -CH2- group can be replaced by cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, preferably by cyclopropylene or 1,3-cyclopentylene, and preferably alkyl or alkenyl,

[0172] 1,3-cyclopentenylene is a moiety selected from the group consisting of the following formulae:

[0173]

[0174] preferably

[0175]

[0176] more preferably

[0177] and

[0178] X 1 F, CI, fluorinated alkyl, fluorinated alkenyl, fluorinated alkoxy or fluorinated alkenyloxy, the latter four radicals preferably having 1 to 4 C atoms, preferably F, CI, CF3 or OCF3, in particular F for formulae I-1 and I-2, and OCF3 for formula I-4, and

[0179] f) again optionally one or more compounds of formula B having a high dielectric constant perpendicular to the director and parallel to the director, the concentration of which is preferably in the range from 1 to 60 %, more preferably in the range from 5 to 40 %, particularly preferably in the range from 8 to 35 %,

[0180]

[0181] wherein

[0182] denotes

[0183]

[0184] represents

[0185]

[0186] R B1 and R B2 independently of one another alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7 C atoms, wherein one -CH2- group can be replaced by cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, preferably by cyclopropylene or 1,3-cyclopentylene, alkenyl having 2 to 7 C atoms, alkenyloxy, alkoxyalkyl or fluorinated alkenyl, wherein one -CH2- group can be replaced by cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, preferably by cyclopropylene or 1,3-cyclopentylene, and preferably alkyl, alkoxy, alkenyl or alkenyloxy, most preferably alkyl, alkoxy or alkenyloxy, and

[0187] n denotes 0 or 1, preferably 0.

[0188] g) optionally again one or more compounds of formula S having a high dielectric constant perpendicular to the director and parallel to the director, the concentration of which is preferably in the range from 1 to 60 %, more preferably in the range from 5 to 40 %, particularly preferably in the range from 8 to 35 %,

[0189]

[0190] wherein

[0191] represents

[0192]

[0193] represents

[0194]

[0195] R S1 and R S2independently of one another alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, preferably having 1 to 7 C atoms, wherein one -CH2- group can be replaced by cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, preferably by cyclopropylene or 1,3-cyclopentylene, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 C atoms, wherein one -CH2- group can be replaced by cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, preferably by cyclopropylene or 1,3-cyclopentylene, and preferably alkyl, alkoxy, alkenyl or alkenyloxy, most preferably alkyl, alkoxy or alkenyloxy, and

[0196] n denotes 0 or 1, preferably 1.

[0197] The liquid-crystalline medium according to the application preferably has a nematic phase.

[0198] In the compounds of the formula I, the group N(R 13 ) can also preferably be an amine. 14

[0199] Preference is given to the following embodiments:

[0200] p is 2,

[0201] is an organic group having 4 binding sites, preferably an alkatetra radical unit having 1 to 30 C atoms, wherein, in addition to the m groups R 12 present in the molecule, but independently thereof, one further H atom can be replaced by R 12 or a plurality of further H atoms can be replaced by R 12 , preferably a mon- or divalent alkatetra radical unit on each of the two terminal C atoms, wherein one -CH2- group or a plurality of -CH2- groups can be replaced by -O- or -(C=0)- in such a way that the two O atoms are not directly bonded to one another, or a substituted or unsubstituted aromatic or heteroaromatic hydrocarbon radical having up to 8 valencies, wherein, in addition to the m groups R 12 present in the molecule, but independently thereof, one further H atom can be replaced by R 12 or a plurality of further H atoms can be replaced by R 12 , denotes (biphenyl-1,1 ',3,3'-tetrayl), (benzene-1,2,4,5-tetrayl), >CH-[CH2] r -CH- (wherein r e {0, 1, 2, 3, 4, 5 to 18}, -CH2- (CH-)-[CH2] q ​-CH2- (wherein r e {0, 1, 2, 3, 4, 5 to 18}) or represents (benzene-1,3,5-triyl), (benzene-1,2,4-triyl) or >CH-[CH2] r -CH2- (wherein r e {0, 1, 2, 3, 4, 5 to 18}) or represents -CH2-[CH2] r -CH2- (wherein r e {0, 1, 2, 3, 4, 5 to 18}) or (1,4-phenylene), (1,3-phenylene), (1,2-phenylene) or (1,4-cyclohexylene)

[0202] In an alternative preferred embodiment,

[0203] p represents 1.

[0204] In the present application, all elements include their respective isotopes. In particular, one or more H in a compound can be replaced by D and this is in some embodiments also particularly preferred. The respective highly deuterated compounds enable, for example, monitoring and discrimination of the compounds. This is very helpful in some cases, in particular in the case of compounds of the formula I.

[0205] In the present application,

[0206] alkyl particularly preferably represents a linear alkyl radical, in particular CH3-, C2H5-, n-C3H7-, n-C4H9- or n-C5H 11 -, and

[0207] alkenyl particularly preferably represents CH2=CH-, E-CH3-CH=CH-, CH2=CH-CH2-CH2-, E-CH3-CH=CH-CH2-CH2-, E-(n-C3H7)-CH=CH-.

[0208] The liquid-crystalline medium according to the application preferably comprises a total of 1 ppm to 2500 ppm, preferably 1 ppm to 1500 ppm, preferably 1 to 600 ppm, even more preferably 1 to 250 ppm, preferably to 200 ppm, and very particularly preferably 1 ppm to 100 ppm, of compounds of the formula I.

[0209] In a preferred embodiment of the application, in the compounds of formula I, denotes denotes denotes denotes denotes denotes denotes -(CH2-)2, -(CH2-)3, -(CH2-)4, -(CH2-)5, -(CH2-)6, -(CH2-)7, -(CH2-)8, i.e. ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl,

[0210] denotes (1,4-phenylene),

[0211] denotes (1,3-phenylene),

[0212] denotes (1,2-phenylene) or

[0213] denotes (trans-1,4-cyclohexylidene) and / or

[0214] denotes -Z 12 denotes -S 11 denotes -Z 11 denotes independently of each other on each occurrence -O-, S 11 denotes -O-, -O-S 11 denotes -O-, -(C=O)-O-S 11 denotes -O-, -O-(C=O)-S 11 denotes -O-, -O-(C=O)-S 11 denotes -(C=O)-O-, -O-S 11 denotes -(C=O)-O-, -(C=O)-O-S 11 denotes -C, -(C=O)-O-S 11 denotes -O-(C=O)- or -(N-R 13 ) -S 11 denotes -O-, -(N-R 13 denotes -C(=O)-S 11 denotes -(C=O)-O or a single bond, preferably -O-, -S 11 denotes -O-, -O-S 11 denotes -O-, -(C=O)-O-S 11 denotes -O-, -O-(C=O)-S 11-O- or -O-S 11 -(C=O)-O-, and / or

[0215] S 11 preferably alkylene having 1 to 20 C atoms, and / or

[0216] R 11 if present, alkyl, alkoxy or H, preferably H or alkyl, and / or

[0217] R 12 H, methyl, ethyl, propyl, isopropyl or 3-heptyl, or cyclohexyl.

[0218] In a preferred embodiment of the application, in the compound of formula I,

[0219]

[0220] represents a group selected from the following formulae

[0221]

[0222]

[0223] In a preferred embodiment of the application, in the compound of formula I,

[0224]

[0225] represents a group selected from the following formulae

[0226]

[0227] In a preferred embodiment of the application, in the compound of formula I, wherein p preferably represents 1,

[0228] represents preferably -O-S 11 -O-,-S 11 -O- or -O-S 11 -, particularly preferably -O-S 11 -O- or -S 11 -O-.

[0229] In a further preferred embodiment of the application, in the compound of formula I,

[0230]

[0231] preferably represents a group selected from the following formulae

[0232]

[0233]

[0234] In a further preferred embodiment of the application, wherein p is 2, which can be the same or different from those described above, in the compounds of the formula I,

[0235]

[0236] preferably denotes a radical selected from the group consisting of

[0237]

[0238] In a further preferred embodiment of the application, which can be the same or different from those described above, in the compounds of the formula I, the radical

[0239]

[0240] independently of one another in each occurrence denote

[0241]

[0242]

[0243] preferably

[0244]

[0245] In a particularly preferred embodiment of the application, in the compounds of the formula I, all radicals present are

[0246]

[0247] have the same meaning.

[0248] These compounds are very suitable as stabilizers in liquid-crystalline mixtures. In particular, they stabilize the VHR of the mixtures to UV exposure.

[0249] In a preferred embodiment of the application, the medium according to the application comprises in each case one or more compounds of the formula I, which are selected from the group of the compounds of the formulae I-1 to I-11 of the following formulae: preferably from the group of the compounds of the formulae I-1 to I-10, particularly preferably from the group of the compounds of the formulae I-2 to I-10, and very particularly preferably from the group of the compounds of the formulae I-2 and / or I-3 and / or I-4,

[0250]

[0251]

[0252]

[0253]

[0254]

[0255] In an even more preferred embodiment of the present application, the medium according to the present application comprises in each case one or more compounds of the formula I which are selected from the following compounds of the formulae 1-1 and / or 1-3 to 1-7 and / or 1-8 and / or 1-9 and / or 1-10.

[0256] In an even more preferred embodiment of the present application, the medium according to the present application comprises in each case one or more compounds of the formula I which are selected from the following compounds of the formulae 1-2 and / or 1-7 and / or 1-9 and / or 1-10.

[0257] In addition to the compounds of the formula I or preferred subformulae thereof, the medium according to the present application preferably comprises one or more compounds of the formula II in a total concentration of 1 % or more to 90 % or less, preferably 10 % or more to 80 % or less, particularly preferably 20 % or more to 70 % or less.

[0258] In a preferred embodiment of the present application, the liquid-crystalline medium comprises one or more compounds of the formulae II-1 and II-2 which are preferably dielectrically positive, preferably have a dielectric anisotropy of 3 or more:

[0259]

[0260] where the parameters have the respective meanings indicated above under formula II, and L 23 and L 24 independently of one another, denote H or F, preferably L 23 denote F, and

[0261] have one of the meanings given for X in the case of formulae II-1 and II-2 has one of the meanings given for 2 preferably denotes F or OCF3, particularly preferably F, and in the case of formula II-2, independently of one another, preferably denote

[0262] In addition to the compounds of the formula I or preferred subformulae thereof, the medium according to the present application preferably comprises one or more compounds of the formula III in a total concentration of 1 % or more to 40 % or less, preferably 3 % or more to 20 % or less, particularly preferably 4 % or more to 10 % or less.

[0263] The compounds of the formula III are preferably selected from the group consisting of the compounds of the formulae III-1 and III-2:

[0264]

[0265] where the parameters have the meanings given under formula III, and the medium according to the application can replace or, in addition to the compounds of the formulae III-1 and / or III-2, comprise one or more compounds of the formula III-3

[0266]

[0267] where the parameters have the meanings indicated above, and the parameter L 31 and L 32 independently of one another and of the other parameters, denote H or F.

[0268] The liquid-crystalline medium preferably comprises one or more compounds selected from the group consisting of the formulae II-1 and II-2, where L 21 and L 22 and / or L 23 and L 24 each denote F.

[0269] In a preferred embodiment, the liquid-crystalline medium comprises one or more compounds selected from the group consisting of the formulae II-1 and II-2, where L 21 , L 22 , L 23 and L 24 each denote F.

[0270] The liquid-crystalline medium preferably comprises one or more compounds of the formula II-1. The compounds of the formula II-1 are preferably selected from the group consisting of the compounds of the formulae II-1a to II-1e, preferably one or more of the formulae II-1a and / or II-1b and / or II-1d, preferably of the formulae II-1a and / or II-1d or II-1b and / or II-1d, most preferably of the formula II-1d:

[0271]

[0272] where the parameters have the meanings indicated above, and L 25 and L 26 independently of one another and of the other parameters, denote H or F, and preferably, in the formulae II-1a and II-1b, L 21 and L 22 each denote F, in the formulae II-1c and II-1d, L 21 and L 22 each denote F and / or L 23 and L24 all denote F, and in formula II-1 e, L 21 , L 22 and L 23 denote F.

[0273] The liquid-crystalline medium preferably comprises one or more compounds of formula II-2, which are preferably selected from compounds of formulae II-2a to II-2k, preferably one or more compounds of each of formulae II-2a and / or II-2h and / or II-2j:

[0274]

[0275]

[0276] where the parameters have the respective meanings indicated above, and L 25 to L 28 independently of one another denote H or F, preferably L 27 and L 28 both denote H, particularly preferably L 26 denotes H.

[0277] The liquid-crystalline medium preferably comprises a compound selected from formulae II-1 a to II-1 e, wherein L 21 and L 22 both denote F and / or L 23 and L 24 both denote F.

[0278] In a preferred embodiment, the liquid-crystalline medium comprises a compound selected from formulae II-2a to II-2k, wherein L 21 , L 22 , L 23 and L 24 both denote F.

[0279] Especially preferred compounds of formula II-2 are compounds of the following formulae, particularly preferably formulae II-2a-1 and / or II-2h-1 and / or II-2k-2:

[0280]

[0281]

[0282]

[0283] where R 2 and X 2 have the meanings indicated above, and X 2 preferably denotes F.

[0284] The liquid-crystalline medium preferably comprises one or more compounds of formula III-1. The compounds of formula III-1 are preferably selected from the group consisting of compounds of formulae III-1a to III-1j, preferably from formulae III-1c, III-1f, III-1g and III-1j:

[0285]

[0286]

[0287] wherein the parameters have the meanings given above, and preferably wherein the parameters have the respective meanings indicated above, the parameter L 35 and L 36 independently of one another and of the other parameters, denote H or F, and the parameter L 35 and L 36 independently of one another and of the other parameters, denote H or F.

[0288] The liquid-crystalline medium preferably comprises one or more compounds of formula III-1c, which are preferably selected from the group consisting of compounds of formulae III-1c-1 to III-1c-5, preferably of formulae III-1c-1 and / or III-1c-2, most preferably of formula III-1c-1:

[0289]

[0290] wherein R 3 have the meanings indicated above.

[0291] The liquid-crystalline medium preferably comprises one or more compounds of formula III-1f, which are preferably selected from the group consisting of compounds of formulae III-1f-1 to III-1f-6, preferably of formulae III-1f-1 and / or III-1f-2 and / or III-1f-3 and / or III-1f-6, more preferably of formulae III-1f-3 and / or III-1f-6, more preferably of formula III-1f-6:

[0292]

[0293]

[0294] wherein R 3 have the meanings indicated above.

[0295] The liquid-crystalline medium preferably comprises one or more compounds of formula III-1g, which are preferably selected from the group consisting of compounds of formulae III-1g-1 to III-1g-5, preferably of formula III-1g-3:

[0296]

[0297]

[0298] wherein R 3 have the above indicated meanings.

[0299] The liquid-crystalline medium preferably comprises one or more compounds of formula III-1 h, which are preferably selected from compounds of formulae III-1 h-1 to III-1 h-3, preferably of formula III-1 h-3:

[0300]

[0301] where the parameters have the above given meanings, and X 3 preferably denotes F.

[0302] The liquid-crystalline medium preferably comprises one or more compounds of formula III-1 i, which are preferably selected from compounds of formulae III-1 i-1 and III-1 i-2, preferably of formula III-1 i-2:

[0303]

[0304] where the parameters have the above given meanings, and X 3 preferably denotes F.

[0305] The liquid-crystalline medium preferably comprises one or more compounds of formula III-1 j, which are preferably selected from compounds of formulae III-1 j-1 and III-1 j-2, preferably of formula III-1 j-1:

[0306]

[0307] where the parameters have the above given meanings.

[0308] The liquid-crystalline medium preferably comprises one or more compounds of formula III-2. The compounds of formula III-2 are preferably selected from compounds of formulae III-2a and III-2b, preferably of formula III-2b:

[0309]

[0310] where the parameters have the above indicated respective meanings, and the parameter L 33 and L 34 independently of one another and of the other parameters, denote H or F.

[0311] The liquid-crystalline medium preferably comprises one or more compounds of formula III-2a, which are preferably selected from compounds of formulae III-2a-1 to III-2a-6:

[0312]

[0313] wherein R 3 have the above indicated meanings.

[0314] The liquid-crystalline medium preferably comprises one or more compounds of formula III-2b, which are preferably selected from compounds of formulae III-2b-1 to III-2b-4, preferably of formula III-2b-4:

[0315]

[0316] wherein R 3 have the above indicated meanings.

[0317] Instead of or in addition to compounds of formula III-1 and / or III-2, the medium according to the application can also comprise one or more compounds of formula III-3

[0318]

[0319] wherein the parameters have the respective meanings indicated above in formula III.

[0320] These compounds are preferably selected from formulae III-3a and III-3b:

[0321]

[0322] wherein R 3 have the above indicated meanings.

[0323] The liquid-crystalline medium according to the application preferably comprises one or more dielectrically neutral compounds, the dielectric anisotropy of which is preferably -1.5 to 3, preferably selected from compounds of formulae VI, VII, VIII and IX.

[0324] In the present application, all elements include their respective isotopes. In particular, one or more H in a compound can be replaced by D and this is in some embodiments also particularly preferred. The respective highly deuterated compounds enable, for example, detection and identification of the compounds. This is very helpful in certain cases, in particular in the case of compounds of formula I.

[0325] In the present application,

[0326] alkyl in particular preferably denotes a linear alkyl group, in particular CH3-, C2H5-, n-C3H7-, n-C4H9- or n-C5H 11 -, and

[0327] Alkenyl particularly preferably denotes CH2=CH-, E-CH3-CH=CH-, CH2=CH-CH2-CH2-, E-CH3-CH=CH-CH2-CH2- or E-(n-C3H7)-CH=CH-.

[0328] In a preferred embodiment of the application, the medium according to the application comprises one or more compounds of the formula B, preferably of the formula B-1, preferably in a concentration of 1 to 20 %, particularly preferably 2 to 15 % and very particularly preferably 3 to 9 %,

[0329]

[0330] where the parameters have the respective meanings given above under formula B, and preferably

[0331] R B1 and R B2 in each case independently of one another, denote unsubstituted alkyl having 1 to 7 C atoms, alkoxy, oxaalkyl or alkoxyalkyl, or alkenyl or alkenyloxy having 2 to 7 C atoms, preferably each denote alkoxy, and

[0332] L B1 and L B2 in each case independently of one another, denote F or Cl, preferably F.

[0333] In a particularly preferred embodiment, the medium according to the application comprises one or more compounds selected from the group of the compounds of the formulae OH-1 to OH-6,

[0334]

[0335] These compounds are very suitable for the stabilization of the medium with respect to thermal stress.

[0336] In a further preferred embodiment of the application, the medium according to the application comprises, in particular one or more compounds of the formula I, in which p denotes 2 and n denotes 2, 3 or 4, preferably 2 or 3, particularly preferably 3, these media have excellent stability.

[0337] In a further preferred embodiment of the application, the medium according to the application comprises in each case at least one or more compounds of the formula I, in which p denotes 1 and n denotes 3, 4, 5 or 6, preferably 4, and the group -Z 11 -S 11 -Z 12 denotes omega-bisoxaalkylene, i.e. -O-S 11 -O-, these media have excellent stability.

[0338] The application also relates to an electro-optical display or an electro-optical component comprising the liquid-crystalline medium according to the application. Preference is given to electro-optical displays based on the IPS, FFS, VA or ECB effect, preferably based on the IPS or FFS effect, and in particular those which are addressed by means of active-matrix addressing devices.

[0339] The application therefore likewise relates to the use of a liquid-crystalline medium according to the application in an electro-optical display or an electro-optical component, and to a process for the preparation of a liquid-crystalline medium according to the application, characterised in that one or more compounds of the formula I are mixed with one or more compounds of the formula II, preferably with one or more compounds of the subformula II-1, and with one or more further compounds, preferably selected from the group of the compounds of the formulae III and IV and / or V and / or VI to IX and / or IN and / or B and / or S.

[0340] Furthermore, the application relates to a process for the stabilisation of a liquid-crystalline medium which comprises one or more compounds of the formula II and one or more compounds selected from the group of the formulae III to IX, B, S and IN, characterised in that one or more compounds of the formula I are added to the medium.

[0341] In a particularly preferred embodiment, the medium comprises one or more compounds of the formula IV, selected from the group of the compounds of the formulae IV-1 to IV-4, preferably of the formulae IV-1 and / or IV-2,

[0342]

[0343] wherein

[0344] alkyl and alkyl' independently of one another denote an alkyl radical having 1 to 7 C atoms, preferably having 2 to 5 C atoms,

[0345] alkenyl and alkenyl' independently of one another denote an alkenyl radical having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably 2 C atoms.

[0346] alkenyl' denotes an alkenyl radical having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms, and

[0347] alkoxy denotes an alkoxy radical having 1 to 5 C atoms, preferably having 2 to 4 C atoms.

[0348] In a particularly preferred embodiment, the medium according to the application comprises one or more compounds of the formula IV-1 and / or one or more compounds of the formula IV-2.

[0349] Especially preferred compounds of formula IV-1 are compounds selected from the group consisting of

[0350]

[0351] wherein alkyl has the meaning given above and preferably denotes in each case, independently of one another, alkyl having 1 to 6, preferably having 2 to 5 C atoms, and particularly preferably n-alkyl.

[0352] Particularly preferred compounds of formula IV are compounds selected from the group consisting of

[0353]

[0354] In another preferred embodiment, the medium comprises one or more compounds of formula V which are compounds selected from the group consisting of formulae V-1 to V-11, preferably compounds selected from the group consisting of formulae V-1 to V-5,

[0355]

[0356]

[0357] wherein the parameters have the meaning given above under formula V, and

[0358] Y 5 denotes H or F, and preferably

[0359] R 51 denotes alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms, and

[0360] R 52 denotes alkyl having 1 to 7 C atoms, alkenyl having 2 to 7 C atoms or alkoxy having 1 to 6 C atoms, preferably alkyl or alkenyl, particularly preferably alkenyl.

[0361] In another preferred embodiment, the medium comprises one or more compounds of formula V-1 which are compounds selected from the group consisting of formulae V-1 a and V-1 b, preferably formula V-1 b,

[0362]

[0363] wherein

[0364] alkyl and alkyl’ independently of one another denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms,

[0365] alkoxy denotes alkoxy having 1 to 5 C atoms, preferably having 2 to 4 C atoms.

[0366] In another preferred embodiment, the medium comprises one or more compounds of formula V-3, which are compounds selected from formulae V-3a and V-3b,

[0367]

[0368] wherein

[0369] alkyl and alkyl' independently of one another denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms, and

[0370] alkenyl denotes alkenyl having 2 to 7 C atoms, preferably having 2 to 5 C atoms.

[0371] In another preferred embodiment, the medium comprises one or more compounds of formula V-4, which are compounds selected from formulae V-4a and V-4b,

[0372]

[0373] wherein

[0374] alkyl and alkyl' independently of one another denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms.

[0375] In another preferred embodiment, the medium comprises one or more compounds of formula V-5, which are compounds selected from formulae V-5a to V5d, preferably V-5a and / or V-5b,

[0376]

[0377] wherein

[0378] alkyl and alkyl' independently of one another denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms, and

[0379] alkenyl and alkenyl' independently of one another denote alkenyl having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably 4 C atoms.

[0380] The liquid-crystalline medium according to the application can comprise one or more chiral compounds.

[0381] Particularly preferred embodiments of the present application meet one or more of the following conditions, wherein the acronyms (abbreviations) are explained in Tables A to C and illustrated by the examples in Table D.

[0382] i. The birefringence of the liquid-crystalline medium is 0.060 or more, particularly preferably 0.070 or more.

[0383] ii. the birefringence of the liquid-crystalline medium is 0.130 or less, particularly preferably 0.120 or less.

[0384] iii. the birefringence of the liquid-crystalline medium is in the range from 0.090 or more to 0.120 or less.

[0385] iv. the liquid-crystalline medium has a negative dielectric anisotropy, the value of which is 2.0 or more, particularly preferably 3.0 or more.

[0386] v. the liquid-crystalline medium has a negative dielectric anisotropy, the value of which is 5.5 or less, particularly preferably 5.0 or less.

[0387] vi. the liquid-crystalline medium has a negative dielectric anisotropy, the value of which is in the range from 3.6 or more to 5.2 or less.

[0388] vii. the total concentration of compounds of the formula II in the mixture as a whole is 25% or more, preferably 30% or more, and preferably in the range from 25% or more to 49% or less, particularly preferably in the range from 29% or more to 47% or less, and very particularly preferably in the range from 37% or more to 44% or less.

[0389] viii. the liquid-crystalline medium comprises one or more compounds of the formula IV, which are compounds selected from the group consisting of CC-n-V and / or CC-n-Vm, particularly preferably CC-3-V, preferably in a concentration of at most 50% or less, particularly preferably at most 42% or less, and optionally additionally comprises CC-3-V1, preferably in a concentration of at most 15% or less, and / or CC-4-V, preferably in a concentration of at most 20% or less, particularly preferably at most 10% or less.

[0390] ix. the total concentration of compounds of the formula CC-3-V in the mixture as a whole is 20% or more, preferably 25% or more.

[0391] x. the proportion of compounds of the formulae II and III in the mixture as a whole is 10% or more, and preferably 75% or less.

[0392] xi. the liquid-crystalline medium essentially consists of compounds of the formulae I, II, III, IV, V and B and / or S, preferably of compounds of the formulae I, II, III, IV, V and S.

[0393] Furthermore, the application relates to electro-optical displays having active matrix addressing on the basis of the VA or ECB effect, characterized in that they contain a liquid-crystalline medium according to the application as dielectric.

[0394] The liquid-crystalline mixture preferably has a nematic phase range of at least 80 degrees in width and a maximum of 30 mm 2 • s-1 the flow viscosity v 20 .

[0395] The Δε of the liquid-crystalline mixture according to the application is -0.5 to -8.0, in particular -1.5 to -6.0, and very particularly preferably -2.0 to -5.0, where Δε denotes the dielectric anisotropy.

[0396] The rotational viscosity γ1 is preferably 150 mPa-s or less, in particular 120 mPa-s or less and very particularly preferably 120 mPa-s or less.

[0397] The mixtures according to the application are suitable for all IPS and FFS-TFT applications. They are also suitable for all VA applications, for example VAN, MVA, (S)-PVA and ASV applications, and also PALC applications with negative Δε.

[0398] The nematic liquid-crystalline mixture in the display according to the application generally comprises two components A and B, which themselves consist of one or more individual compounds.

[0399] The liquid-crystalline medium according to the application preferably comprises 4 to 15, in particular 5 to 12 and particularly preferably 10 or fewer compounds. These are preferably selected from the compounds of the formulae I, II and III-1 to III-4, and / or IV and / or V.

[0400] The liquid-crystalline medium according to the application can optionally also comprise more than 18 compounds. In this case, they preferably comprise 18 to 25 compounds.

[0401] In addition to the compounds of the formulae I to V, further constituents can also be present, for example in an amount of up to 45%, but preferably up to 35%, in particular up to 10%, of the overall mixture.

[0402] The medium according to the application can also optionally comprise a dielectrically positive component, preferably in an amount of 10% or less, based on the total concentration of the medium.

[0403] In a preferred embodiment, the liquid-crystalline medium according to the application comprises, based on the overall mixture,

[0404] 100 ppm or more to 2500 ppm or less, preferably 300 ppm or more to 2000 ppm or less, particularly preferably 500 ppm or more to 1500 ppm or less, and very particularly preferably 700 ppm or more to 1200 ppm or less, of the compounds of the formula I,

[0405] 20% or more to 60% or less, preferably 25% or more to 50% or less, particularly preferably 30% or more to 45% or less of the compound of formula II, and

[0406] 50% or more to 70% or less of compounds of formulas I to IX and / or IN and / or B and / or S.

[0407] In a preferred embodiment, the liquid crystal medium according to the invention comprises one or more compounds selected from formulas II, III, IV, V, VI, VII, VIII, and IX, preferably compounds selected from formulas II and / or III and / or IV and / or V, which independently comprise one or more rings selected from the following substituted 1,4-phenylene rings.

[0408]

[0409] In a particularly preferred embodiment of the above preferred embodiments, the liquid crystal medium according to the present invention comprises one or more compounds selected from the following

[0410]

[0411]

[0412] In a preferred embodiment, the liquid crystal medium according to the invention comprises one or more compounds selected from formulas II, III, IV, V, VI, VII, VIII, and IX, preferably compounds selected from formulas II and / or III and / or IV and / or V, comprising one end group, or, if present, two end groups, preferably one end group, which is selected from the following end groups.

[0413] 3-Fluoropropyl, cyclopropyl, cyclopropylmethyl, 2-cyclopropylethyl, cyclobutyl, cyclobutylmethyl, cyclopentyl, and cyclopentylmethyl

[0414] Preferably selected from 3-fluoropropyl, cyclopropyl, cyclopropylmethyl, 2-cyclopropylethyl, cyclobutylmethyl and cyclopentylmethyl.

[0415] In a particularly preferred embodiment of the above preferred embodiments, the liquid crystal medium according to the present invention comprises one or more compounds selected from the following

[0416]

[0417]

[0418]

[0419]

[0420]

[0421]

[0422]

[0423] In a preferred embodiment, the liquid-crystalline medium according to the present application comprises compounds selected from formulae I, II, III, IV, V, In, B and S, preferably from formulae I, II and / or III and / or B and / or S; they preferably consist essentially, particularly preferably essentially and very particularly preferably virtually completely, of compounds of said formulae.

[0424] The liquid-crystalline medium according to the present application preferably has a nematic phase in each case at least at -20°C or lower to 70°C or higher, particularly preferably at -30°C or lower to 80°C or higher, very particularly preferably at -40°C or lower to 85°C or higher and most preferably at -40°C or lower to 90°C or higher.

[0425] The expression "having a nematic phase" here means on the one hand that no smectic phase and no crystallization is observed at the respective temperature at low temperature, and on the other hand that no clearing occurs on heating in the nematic phase. The investigation at low temperature is carried out in a flow viscosimeter at the respective temperature and checked by storage in a test cell having a cell gap corresponding to electro-optical applications for at least 100 hours. If the storage stability at a temperature of -20°C is 1000 hours or more in the respective test cell, the medium is regarded as stable at this temperature. At temperatures of -30°C and -40°C, the respective times are 500 hours and 250 hours, respectively. At high temperature, the clearing point is measured in a capillary by conventional methods. Furthermore, the shelf life at low temperature is determined in bulk (1 ml_ sample) in a glass bottle at a temperature of -20°C or -30°C. At these temperatures, preferably at -30°C, the shelf life is preferably 120 hours or more, particularly preferably 240 hours or more.

[0426] In a preferred embodiment, the liquid-crystalline medium according to the present application is characterized by a moderate to low optical anisotropy. The birefringence value is preferably in the range of 0.065 or more to 0.130 or less, particularly preferably in the range of 0.080 or more to 0.120 or less, and very particularly preferably in the range of 0.085 or more to 0.110 or less.

[0427] In this embodiment, the liquid-crystalline medium according to the application has a negative dielectric anisotropy and a relatively high absolute value of the dielectric anisotropy (|Δε|), which is preferably in the range from 2.7 or more to 5.3 or less, preferably to 4.5 or less, preferably from 2.9 or more to 4.5 or less, particularly preferably from 3.0 or more to 4.0 or less and very particularly preferably from 3.5 or more to 3.9 or less.

[0428] The liquid-crystalline medium according to the application has a relatively low threshold voltage (V0) value, which is in the range from 1.7 V or more to 2.5 V or less, preferably from 1.8 V or more to 2.4 V or less, particularly preferably from 1.9 V or more to 2.3 V or less and very particularly preferably from 1.95 V or more to 2.1 V or less.

[0429] In a further preferred embodiment, the liquid-crystalline medium according to the application preferably has a relatively low average dielectric anisotropy value (ε av. ≡ (ε || + 2ε ⊥ ) / 3), which is preferably in the range from 5.0 or more to 7.0 or less, preferably from 5.5 or more to 6.5 or less, still more preferably from 5.7 or more to 6.4 or less, particularly preferably from 5.8 or more to 6.2 or less and very particularly preferably from 5.9 or more to 6.1 or less.

[0430] Furthermore, the liquid-crystalline medium according to the application has a high VHR value in the liquid-crystalline cell.

[0431] In the cell, these are preferably greater than or equal to 95%, preferably greater than or equal to 97%, particularly preferably greater than or equal to 98% and very particularly preferably greater than or equal to 99% in a freshly filled cell at 20°C, and these are greater than or equal to 90%, preferably greater than or equal to 93%, particularly preferably greater than or equal to 96% and very particularly preferably greater than or equal to 98% after baking in the cell at 100°C for 5 minutes.

[0432] Generally, the liquid-crystalline media having a low addressing voltage or threshold voltage here have a lower VHR than those having a higher addressing voltage or threshold voltage, and vice versa.

[0433] The preferred values of these individual physical properties are also preferably maintained in each case in combination with one another by the medium according to the application.

[0434] In this application, the term "compound" is written as "(one or more) compound" also means both one and more compounds, unless explicitly indicated otherwise.

[0435] Unless indicated otherwise, the individual compounds are generally used in the mixture in a concentration of 1 % or more to 30 % or less, preferably 2 % or more to 30 % or less and particularly preferably 3 % or more to 16 % or less in each case.

[0436] In a preferred embodiment, the liquid-crystalline medium according to the invention comprises

[0437] one or more compounds of formula I and

[0438] one or more compounds of formula IV, preferably selected from the group consisting of compounds of formulae CC-n-V and CC-n-Vm, preferably CC-3-V, CC-3-V1, CC-4-V and CC-5-V, particularly preferably selected from the group consisting of compounds CC-3-V, CC-3-V1 and CC-4-V, very particularly preferably compound CC-3-V and, optionally additionally, one or more compounds CC-4-V and / or CC-3-V1.

[0439] In a preferred embodiment, the liquid-crystalline medium according to the invention comprises:

[0440] one or more compounds of formula I and / or

[0441] one or more compounds of formula II, preferably of formulae PUQU-n-F, CDUQU-n-F, APUQU-n-F, DPUQU-n-F and PGUQU-n-F and / or

[0442] one or more compounds of formula III, preferably of formulae CCG-n-FCCP-n-OT, CLP-n-T, CGG-n-F, CGG-n-OD and PPGU-n-F and / or

[0443] one or more compounds of formula IV, preferably of formulae CC-n-V, CC-n-Vm, CC-n-m, CC-V-V, CCVC-n-V and / or

[0444] one or more compounds of formula V, preferably of formulae CP-n-Om, CCP-n-m, CCP-V-n, CCP-V2-n, CLP-V-n, CCVC-n-V, CGP-n-m, PGP-n-m, PGP-n-mV and CPGP-n-m and / or

[0445] optionally, preferably necessarily, one or more compounds of formula VI, preferably of formulae Y-n-Om, Y-nO-Om and / or CY-n-Om, selected from the group consisting of formulae Y-3-O1, Y-4O-O4, CY-3-O2, CY-3-O4, CY-5-O2 and CY-5-O4 and / or

[0446] Optionally, preferably necessarily, one or more compounds of formula VII-1, preferably selected from compounds of formulae CCY-n-m and CCY-n-Om, preferably compounds of formula CCY-n-Om, preferably selected from compounds of formulae CCY-3-O2, CCY-2-O2, CCY-3-O1, CCY-3-O3, CCY-4-O2, CCY-3-O2 and CCY-5-O2, and / or

[0447] Optionally, preferably necessarily, one or more compounds of formula VII-2, preferably of formula CLY-n-Om, preferably selected from compounds of formulae CLY-2-O4, CLY-3-O2, CLY-3-O3 and / or

[0448] one or more compounds of formula VIII, preferably of formulae CZY-n-On and CCOY-n-m and / or

[0449] one or more compounds of formula IX, preferably selected from compounds of formulae PYP-n-m and PGIY.n-Om and / or

[0450] one or more compounds of formula B and / or

[0451] one or more compounds of formula S and / or

[0452] Optionally, preferably necessarily, one or more compounds of formula IV, preferably selected from compounds of formulae CC-n-V, CC-n-Vm and CC-nV-Vm, preferably CC-3-V, CC-3-V1, CC-4-V, CC-5-V and CC-V-V, particularly preferably selected from compounds CC-3-V, CC-3-V1, CC-4-V and CC-V-V, very particularly preferably compound CC-3-V, and optionally additionally one or more compounds CC-4-V and / or CC-3-V1 and / or CC-V-V.

[0453] In a particularly preferred embodiment of the present application, the medium according to the present application comprises one or more compounds of formula PPGU-n-F. Compounds of formula PPGU-n-F are also very suitable for use as stabilizers in liquid-crystalline mixtures.

[0454] In a particularly preferred embodiment of the present application, the medium according to the present application comprises one or more compounds of formula IX.

[0455] Compounds of formula IX are also very suitable for use as stabilizers in liquid-crystalline mixtures, in particular in the case where p = q = 1 and ring A 9 = 1,4-phenylene. In particular, they stabilize the VHR of the mixture to UV exposure.

[0456] In a preferred embodiment, the medium according to the present application comprises one or more compounds of formula IX, which are selected from one or more of the formulae of the compounds of formulae IX-1 to IX-4, very particularly preferably of formulae IX-1 to IX-3,

[0457]

[0458] wherein the parameters have the meanings given under formula IX, F / H denotes F or H.

[0459] In another preferred embodiment, the medium comprises one or more compounds of formula IX-3, preferably of formula IX-3-a,

[0460]

[0461] alkyl and alkyl’ independently of one another denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms.

[0462] In the case of the use of compounds of formula IX in the liquid-crystalline medium according to the present application, they are preferably present in a concentration of 20% or less, more preferably 10% or less, most preferably 5% or less and for individual compounds, i.e. (homologous) compounds, the concentration is preferably 10% or less and more preferably 5% or less.

[0463] For the present application, the following definitions apply in each case in connection with the description of the composition constituents, unless indicated otherwise:

[0464] “comprise”: the concentration of the component in question in the composition is preferably 5% or more, particularly preferably 10% or more and very particularly preferably 20% or more,

[0465] “consists essentially of”: the concentration of the component in question in the composition is preferably 50% or more, particularly preferably 55% or more and very particularly preferably 60% or more,

[0466] “consists essentially of”: the concentration of the component in question in the composition is preferably 50% or more, particularly preferably 55% or more and very particularly preferably 60% or more,

[0467] “consists essentially of”: the concentration of the component in question in the composition is preferably 50% or more, particularly preferably 55% or more and very particularly preferably 60% or more,

[0468] This applies to the medium as a composition with its constituents, which can be components and compounds, and also to the components with their constituents, the compounds. The term "comprising" means that the concentration of the compound in question is preferably 1% or more, particularly preferably 2% or more, very particularly preferably 4% or more, only when the concentration of the individual compounds relative to the entire medium is concerned.

[0469] For the present application, "<" means less than or equal to, preferably less than, and ">" means greater than or equal to, preferably greater than.

[0470] For the present application,

[0471]

[0472] represents trans-1,4-cyclohexylene,

[0473]

[0474] represents 1,4-cyclohexylene, preferably trans-1,4-cyclohexylene, and

[0475]

[0476] represents 1,4-phenylene.

[0477] For the present application, the expression "dielectrically positive compound" means a compound with a Δε > 1.5, the expression "dielectrically neutral compound" generally means those with -1.5 < Δε < 1.5 and the expression "dielectrically negative compound" means those with a Δε < -1.5. The dielectric anisotropy of the compounds here is determined in each case by dissolving 10% of the compound in a liquid crystal host and measuring the capacitance of the resulting mixture at 20°C at a frequency of 1 kHz in at least one test cell with a homeotropic alignment and with a planar alignment having a cell thickness of 20 μιη. The measurement voltage is generally 1.0 V, but is always below the threshold of the electrical capacitance of the respective liquid crystal mixture under investigation.

[0478] The host mixture for the dielectrically positive and dielectrically neutral compounds is ZLI-4792 and the host mixture for the dielectrically negative compounds is ZLI-2857, both from Merck KGaA, Germany. The values of the respective compounds to be investigated are obtained from the change in the dielectric constant of the host mixture after addition of the compound to be investigated and extrapolated to 100% of the compound employed. The compound to be investigated is dissolved in the host mixture in an amount of 10%. If the solubility of the substance is too low for this purpose, the concentration is halved stepwise until the investigation can be carried out at the desired temperature.

[0479] The compounds of the formula I according to the application or the compounds of the formula I for use according to the application can advantageously be prepared according to the following reaction schemes.

[0480] Synthesis scheme 1

[0481]

[0482] wherein n preferably denotes 2, 3 or 4, particularly preferably 3 or 4.

[0483] Synthesis scheme 2

[0484]

[0485] wherein n preferably denotes 2, 3 or 4, particularly preferably 3 or 4.

[0486] Synthesis scheme 3

[0487]

[0488] wherein m denotes an integer from 3 to 6, particularly preferably 4 or 6.

[0489] In the above reaction schemes, Pg denotes a protecting group, and Rg denotes a leaving group, and the parameter n has the meaning given in the case of formula I, furthermore, R 1 has the meaning given in the case of formula I for R 11 , the ring structure has the meaning given in the case of formula I for ZG, Sp 1 and Sp 2 each have the meaning given in the case of formula I for S 1 and S 2 , and preferably n denotes 3 or 4, the ring structure denotes an aromatic or aliphatic radical, Sp 1 and Sp 2 denote a single bond or an alkylene radical having 1 to 8 C atoms, and R 1 denotes an alkyl radical having 1 to 8 C atoms.

[0490] For the present application, the following definitions apply in each case in connection with the description of the composition constituents, unless indicated otherwise:

[0491] "comprise": the concentration of the component in question in the composition is preferably 5% or more, particularly preferably 10% or more, very particularly preferably 20% or more,

[0492] "consists essentially of": the concentration of the component in question in the composition is preferably 50% or more, particularly preferably 55% or more and very particularly preferably 60% or more,

[0493] "consisting essentially of": the concentration of the ingredient in question in the composition is preferably 80% or more, particularly preferably 90% or more and very particularly preferably 95% or more, and

[0494] "consisting essentially of": the concentration of the ingredient in question in the composition is preferably 80% or more, particularly preferably 90% or more and very particularly preferably 95% or more, and

[0495] This applies to media which are compositions with their ingredients, which can be components and compounds, and also to components with their ingredients, the compounds. Only when referring to the concentration of individual compounds relative to the entire medium does the term "comprising" mean that the concentration of the compound in question is preferably 1% or more, particularly preferably 2% or more, very particularly preferably 4% or more.

[0496] For the present application, "<" means less than or equal to, preferably less than, and ">" means greater than or equal to, preferably greater than.

[0497] For the present application,

[0498]

[0499] denotes trans-1,4-cyclohexylene, and

[0500]

[0501] denotes 1,4-phenylene.

[0502] For the present application, the expression "dielectrically positive compound" means a compound with a Δε > 1.5, the expression "dielectrically neutral compound" means those with -1.5 < Δε < 1.5 and the expression "dielectrically negative compound" means those with a Δε < -1.5. The dielectric anisotropy of the compounds is here determined in each case by dissolving 10% of the compound in a liquid crystal host and measuring the capacitance of the resulting mixture in at least one test cell with a homeotropic alignment and with a planar alignment at 1 kHz, with a cell thickness of 20 pm. The measurement voltage is usually 0.5 to 1.0 V, but is always below the threshold of the electrical capacitance of the respective liquid crystal mixture investigated.

[0503] The host mixture for dielectrically positive and dielectrically neutral compounds is ZLI-4792 and for dielectrically negative compounds is ZLI-2857, both from Merck KGaA, Germany. The values of the respective compounds to be investigated are obtained from the change in the dielectric constant of the host mixture after addition of the compound to be investigated and extrapolated to 100% of the compound employed. The compound to be investigated is dissolved in the host mixture in an amount of 10%. If the solubility of the substance is too low for this purpose, the concentration is halved stepwise until the investigation can be carried out at the desired temperature.

[0504] The liquid-crystalline medium according to the application can also comprise further additives, such as stabilizers and / or pleochroic dyes and / or chiral dopants, if necessary, in usual amounts. The amount of these additives employed is preferably 0% or more to 10% or less, particularly preferably 0.1% or more to 6% or less, based on the amount of the entire mixture. The concentration of the individual compounds employed is preferably 0.1% or more to 3% or less. When specifying the concentration and concentration range of the liquid-crystalline compounds in the liquid-crystalline medium, the concentration of these and similar additives is generally not taken into account.

[0505] In a preferred embodiment, the liquid-crystalline medium according to the application comprises a polymer precursor, which comprises one or more reactive compounds, preferably reactive mesogens, and, if necessary, further additives, such as polymerization initiators and / or polymerization moderators, in usual amounts. The amount of these additives employed is 0% or more to 10% or less, preferably 0.1% or more to 2% or less, based on the amount of the entire mixture. When specifying the concentration and concentration range of the liquid-crystalline compounds in the liquid-crystalline medium, the concentration of these and similar additives is not taken into account.

[0506] The composition consists of a plurality of compounds, preferably 3 or more to 30 or less, particularly preferably 6 or more to 20 or less and very particularly preferably 10 or more to 16 or less compounds, which are mixed in the usual way. Usually, the desired amount of the components used in smaller amounts is dissolved in the components which constitute the main constituents of the mixture. This is advantageously carried out at elevated temperature. If the temperature chosen is above the clearing point of the main constituents, it is particularly easy to observe that the dissolution operation is complete. However, the liquid-crystalline mixture can also be prepared in other usual ways, for example using premixes or from so-called "multi-bottle systems".

[0507] The mixtures according to the application exhibit a very wide nematic phase range with a clearing point of 65°C or more, a very advantageous capacitance threshold, a relatively high holding ratio value and at the same time very good low-temperature stability at -30°C and -40°C. Furthermore, the mixtures according to the application are characterized by a low rotational viscosity γ1.

[0508] It is self-evident to the person skilled in the art that the media according to the application for VA, IPS, FFS or PALC displays can also comprise compounds in which, for example, H, N, O, CI, F has been replaced by the corresponding isotope.

[0509] The structure of the liquid crystal display according to the application corresponds to the general geometry, for example described in EP-A 0 240 379.

[0510] The liquid crystal phases according to the application can be improved by suitable additives in such a way that they can be used in any type of hitherto disclosed LCD display, for example ECB, VAN, IPS, GH or ASM-VA.

[0511] The following table E shows possible dopants which can be added to the mixtures according to the application. If the mixture comprises one or more dopants, it / these is / are used in an amount of 0.01 % to 4 %, preferably 0.1 % to 1.0 %.

[0512] The stabilizers which can be added to the mixtures according to the application, for example preferably in an amount of 0.01 % to 6 %, in particular 0.1 % to 3 %, are shown in table F below.

[0513] For the purposes of the present application, all concentrations are indicated in percent by weight, unless explicitly stated otherwise, and relate to the respective mixture or mixture component, unless explicitly indicated otherwise.

[0514] Unless explicitly indicated otherwise, all temperature values indicated in this application, such as melting point T(C,N), transition from smectic (S) to nematic (N) phase T(S,N) and clearing point T(N,I), are indicated in degrees Celsius (°C) and all temperature differences correspondingly in degree difference (° or degrees).

[0515] For the purposes of the present application, the term "threshold voltage" refers to the capacitive threshold (V0), also called Freedericks-threshold, unless explicitly indicated otherwise.

[0516] All physical properties are and have been determined in accordance with "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status November 1997, Merck KGaA, Germany, and apply to a temperature of 20 °C, and Δn is determined at 589 nm and Δε is determined at 1 kHz, in each case unless explicitly indicated otherwise.

[0517] As switching behavior, electro-optical properties, such as threshold voltage (V0) (capacitive measurement), were measured in test cells produced by Merck Japan. The measurement cells have a soda lime glass substrate and are constructed in an ECB or VA configuration with a polyimide alignment layer (SE-1211 (mixing ratio 1 : 1) using diluent ** 26, both from Nissan Chemicals, Japan) which has been rubbed perpendicular to each other and influences the homeotropic alignment of the liquid crystal. The transparent, almost square ITO electrodes have a surface area of 1 cm 2 .

[0518] Unless otherwise stated, no chiral dopant was added to the liquid crystal mixtures used, but the latter are also particularly suitable for use in applications where this type of doping is necessary.

[0519] VHR was determined in test cells produced by Merck Japan. The measurement cells have a soda lime glass substrate and are constructed using a 50 nm thick polyimide alignment layer (e.g. AL-3046 from Japan Synthetic Rubber, Japan) which has been rubbed perpendicular to each other or with the alignment layers described in the examples which have been rubbed perpendicular to each other. The layer thickness is uniform at 6.0 μιη. The transparent ITO electrodes have a surface area of 1 cm 2 .

[0520] VHR was determined in an instrument commercially available from Autronic Melchers, Germany, after 5 minutes in an oven at 20°C (VHR 20 ) and at 100°C (VHR 100 ). The voltage used has a frequency of 60 Hz or the conditions shown in the examples.

[0521] The accuracy of the VHR measurement depends on the respective value of the VHR. The precision decreases with decreasing values. Deviations which are generally observed in the case of values in various orders of magnitude are compiled in the table below by their order of magnitude.

[0522]

[0523] The stability against UV radiation was investigated in a commercial instrument "Suntest CPS" from Heraeus, Germany. The sealed test cells were irradiated for 2.0 hours without additional heating. The irradiation power in the wavelength range from 300 nm to 800 nm is 765 W / m 2V, or the conditions indicated in the examples. In order to simulate the so-called window glass mode, a UV "cut-off" filter with an edge wavelength of 310 nm was used. In each series of experiments, at least four test cells were investigated for each condition, and the corresponding results were expressed as the average of the corresponding individual measurements. The decrease in voltage holding ratio (AVHR) generally caused by UV irradiation of the exposure, for example by the LCD backlight, can be determined according to the following equation (1):

[0524] AVHR(t) = VHR(t) - VHR(t=0) (1).

[0525] The relative stability (S(t)) of the LC mixture for the load at time t was determined according to the following equation (2): rel

[0526]

[0527] where "ref" stands for the corresponding unstable mixture.

[0528] Another characteristic quantity of the conductivity of the liquid crystal mixture, in addition to the VHR, is the ion density. High values of the ion density often lead to the occurrence of display malfunctions, such as image sticking and flickering. The ion density is preferably determined in a test cell produced by Merck Japan Ltd. The test cell has a substrate made of soda-lime glass and is designed with a polyimide alignment layer (e.g. AL-3046 from Japan Synthetic Rubber, Japan) having a polyimide layer thickness of 40 nm, unless stated otherwise. The layer thickness of the liquid crystal mixture is 6.0 pm uniformly. In addition, the area of the circular transparent ITO electrode, which is equipped with a guard ring, is 1 cm 2 . The accuracy of the measurement method is approximately ± 15%. The liquid crystal cell is dried in an oven at 120°C overnight and then filled with the relevant liquid crystal mixture.

[0529] ​The ion density was measured using an instrument commercially available from TOYO, Japan. The measurement method is essentially a kind of cyclic voltammetry-like measurement method as described in M. Inoue, "Recent Measurement of Liquid Crystal Material Characteristics", Proceedings IDW 2006, LCT-7-1, 647. In this method, the applied direct current voltage is varied between positive and negative maximum values according to a pre-specified triangular curve. Thus, a complete run through the curve forms one measurement cycle. If the applied voltage is large enough for the ions in the field to be able to move to the respective electrode, an ionic current is formed due to the discharge of the ions. The amount of charge transferred here is typically in the range of a few pC to a few nC. This makes a highly sensitive detection ensured by the above-mentioned instrument necessary. The result is represented in a current / voltage curve. The ionic current here is evident from the peak occurring at voltages smaller than the threshold voltage of the liquid crystal mixture. The integration of the peak area gives the value of the ion density of the mixture under investigation. Four test cells were measured for each mixture. The repetition frequency of the triangular voltage was 0.033 Hz, the measurement temperature was 60 °C, the maximum voltage was ± 3 V to ± 10 V, depending on the order of magnitude of the dielectric anisotropy of the relevant mixture.

[0530] The rotational viscosity was measured using the rotating permanent magnet method and the flow viscosity was measured in a modified Ubbelohde viscometer. For the liquid crystal mixtures ZLI-2293, ZLI-4792 and MLC-6608 (all products from Merck KGaA, Darmstadt, Germany) the rotational viscosity values determined at 20 °C were 161 mPa-s, 133 mPa-s and 186 mPa-s, respectively, and the flow viscosity values (v) were 21 mm 2 ·s -1 , 14 mm 2 ·s -1 and 27 mm 2 ·s -1 , respectively.

[0531] The following symbols are used unless explicitly stated otherwise:

[0532] V0denotes the capacitive [V] threshold voltage at 20 °C;

[0533] n e denotes the extraordinary refractive index measured at 20 °C and 589 nm,

[0534] n o denotes the ordinary refractive index measured at 20 °C and 589 nm,

[0535] Δn denotes the optical anisotropy measured at 20°C and 589 nm,

[0536] ε ⊥ denotes the dielectric anisotropy measured at 20°C and 1 kHz perpendicular to the director,

[0537] ε || denotes the dielectric anisotropy measured at 20°C and 1 kHz parallel to the director,

[0538] Δε denotes the dielectric anisotropy measured at 20°C and 1 kHz,

[0539] cl.p. or

[0540] T(N, I) denotes the clearing point [°C],

[0541] ν denotes the flow viscosity measured at 20°C [mm 2 ·s -1 ],

[0542] γ1 denotes the rotational viscosity measured at 20°C [mPa-s],

[0543] K1 denotes the elastic constant for "stretch" deformation at 20°C [pN],

[0544] K2 denotes the elastic constant for "twist" deformation at 20°C [pN],

[0545] K3 denotes the elastic constant for "bend" deformation at 20°C [pN], and

[0546] LTS denotes the low temperature stability of the phase measured in a test cell,

[0547] VHR denotes the voltage holding ratio,

[0548] ΔVHR denotes the decrease of the voltage holding ratio, and

[0549] S rel denotes the relative stability of the VHR.

[0550] The following examples illustrate the present application without limiting it. They show, however, to the person skilled in the art the preferred mixture concepts using the compounds to be employed and their respective concentrations as well as their combinations with each other. Furthermore, the examples elucidate the properties and property combinations which can be obtained.

[0551] For the present application and in the following examples, the structure of the liquid crystalline compounds is indicated by the acronyms which are translated into chemical formulae according to the following Tables A to C. All groups C n H 2n+1 , C m H 2m+1 and C l H2l+1 or C n H 2n , C m H2 m and C l H 2l are straight-chain alkyl or alkylene groups, each having n, m and I C atoms, respectively. Table A shows the codes for the ring elements of the compound nucleus, Table B lists the bridging units, and Table C lists the symbolic meanings of the left-hand and right-hand end groups. The acronyms consist of the code for the ring element with optional linking groups, followed by a first hyphen and the code for the left-hand end group, and a second hyphen and the code for the right-hand end group. Table D shows exemplary structures of the compounds and their respective abbreviations.

[0552] Table A: Ring elements

[0553]

[0554]

[0555]

[0556]

[0557]

[0558]

[0559] Table B: Bridging units

[0560] Table C: End groups

[0561]

[0562]

[0563] wherein n and m are each an integer, and the three dots "..." are a placeholder for further abbreviations from this table.

[0564] In addition to the compounds of the formula I, the mixtures according to the application preferably also comprise one or more of the following-mentioned compounds.

[0565] The following abbreviations are used:

[0566] (n, m and z are each, independently of one another, an integer, preferably from 1 to 6)

[0567] Table D

[0568]

[0569]

[0570]

[0571]

[0572]

[0573]

[0574]

[0575]

[0576]

[0577]

[0578]

[0579]

[0580]

[0581]

[0582]

[0583]

[0584] Table E shows chiral dopants which are preferably used in the mixtures according to the application.

[0585] Table E

[0586]

[0587]

[0588] In a preferred embodiment of the application, the medium according to the application comprises one or more compounds selected from the group of compounds of Table E.

[0589] Table F shows stabilizers which can preferably be used in the mixtures according to the application in addition to the compounds of the formula I. Here, the parameter n denotes an integer in the range from 1 to 12. In particular, the shown phenolic derivatives can be used as additional stabilizers since they act as antioxidants.

[0590] Table F

[0591]

[0592]

[0593]

[0594]

[0595] In a preferred embodiment of the application, the medium according to the application comprises one or more compounds selected from the group of compounds of Table F, in particular one or more compounds selected from the group of the following two formulae.

[0596] Examples

[0597] The following examples illustrate the application without limiting it in any way. The physical properties make it clear to the person skilled in the art what properties can be achieved and within what ranges they can be varied. In particular, a combination of various properties which can preferably be achieved is thus well defined for the person skilled in the art.

[0598] Material Examples

[0599] The following substances are preferred substances according to the application of the formula I or substances of the formula I which are preferably used according to the application.

[0600] 1

[0601] 2

[0602] 3

[0603] 4

[0604] 5

[0605] 6

[0606] 7

[0607] and

[0608] 8

[0609] 9

[0610] and

[0611] 10

[0612] 11

[0613] The following examples illustrate the application without limiting it in any way. The physical properties make it clear to the person skilled in the art what properties are to be achieved and in what ranges they can be varied. In particular, the various property combinations which can preferably be achieved are thus well defined for the person skilled in the art.

[0614] Synthesis Example 1: Synthesis of bis(l-oxy-2,2,6,6-tetramethylpiperidin-4-yl) 2-{3-[2,5-bis({4-butyl-5-[(l-oxy-2,2,6,6-tetramethylpiperidin-4-yl)oxy]-4-{[(l-oxy-2,2,6,6-tetramethylpiperidin-4-yl)oxy]carbonyl}-5-oxopentyl})phenyl]propyl}-2-butylmalonate 1

[0615] (Substance Example 1)

[0616]

[0617] Step 1.1 : Synthesis of 3-[3,4-bis(3-hydroxypropyl)phenyl]propan-1-ol A

[0618]

[0619] A solution of 51.34 g (484.0 mmol) of anhydrous sodium carbonate in 171.7 ml of water was prepared. A solution of 25.0 g (79.0 mmol) of 1,2,4-tribromobenzene and 67.7 g (476 mmol) of 2-butoxy-1,2-oxaborolane in 965.2 ml of tetrahydrofuran (THF) was prepared, 1.65 ml (11.9 mmol) of triethylamine was added, and the mixture was stirred and degassed using a stream of argon for 30 min. 1.40 g (7.49 mmol) of palladium(II) chloride (59% palladium, anhydrous) and 1.85 g (3.97 mmol) of 2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl were added, and the reaction mixture was stirred at reflux for 18 hours. The reaction mixture was allowed to cool to room temperature (RT), water and methyl tert-butyl ether (MTBE) were added, and the phases were separated. The aqueous phase was extracted with MTBE, and the combined organic phases were washed with a saturated NaCl solution, dried over sodium sulfate, filtered, and evaporated in vacuo. The product was obtained as a light yellow oil and was filtered through silica gel using a mixture of ethyl acetate (EA) and methanol (9:1). The product fractions were combined and evaporated in vacuo to obtain the reaction product as a light yellow oil. The product was characterized by NMR spectroscopy.

[0620] 1H NMR (500 MHz, DMSO-d6)

[0621] δ = 1.66 (m c , 6H, CH2), 2.42 - 2.69 (m (与DMSO叠加) , 6H, CH2,), 3.36 - 3.49 (m, 6H, CH2), 4.44 (t, J = 5.15 Hz, 1H), 4.48 (m c , 2H), 6.92 (dd, J = 1.7, 7.72 Hz, 1H), 6.95 (d, J = 1.53 Hz, 1H), 7.03 (d, J = 7.7 Hz, 1H).

[0622] Step 1.2: Synthesis of 1,2,4-tris(3-iodopropyl)benzene B

[0623]

[0624] Dissolve 30.2 ml (138 mmol) of triphenylphosphine in 513 ml of acetonitrile and add dropwise under gentle cooling a solution of 34.92 g (138.0 mmol) of iodine in 513 ml of acetonitrile. An orange suspension is formed during this addition. When the addition is complete, the mixture is stirred for a further 10 min. Add 13.3 g (197 mmol) of imidazole and subsequently dropwise a solution of 10.0 g (39.3 mmol) of triol A in 100 ml of acetonitrile (a clear yellow solution is formed during this addition). Stir the reaction solution at RT for 3 hours (h) and carefully pour into a cold sodium thiosulfate solution (decolorization occurs) and add heptane. After washing by stirring, separate the phases, extract the aqueous phase with heptane and dry the combined organic phases over sodium sulfate, filter and evaporate in vacuo. Filter the crude product over silica gel with heptane (H) and ethyl acetate (8:2) and evaporate the product fractions to give the product as a colorless oil. Characterize the product by mass spectrometry.

[0625] MS (EI) = 582.0

[0626] Step 1.3: Synthesis of 2-butylmalonyl dichloride C

[0627]

[0628] First 76.00 g (474.5 mmol) 2-butylmalonic acid was introduced into a reaction vessel and warmed to 40 °C. Then 90.00 ml (1.240 mol) thionyl chloride was added dropwise over a period of about 30 minutes (care, gas evolution) and the mixture was stirred for another 5 hours (h) at room temperature (RT). During this time period the evolution of gas decreased significantly. Then the reaction solution was stirred for 18 h at 50 °C and subsequently for 5 h at 70 °C. At each temperature increase a slight evolution of gas occurred again. Then the reaction mixture was cooled to room temperature and dissolved in 300 ml dry toluene and the excess thionyl chloride was separated from the toluene by distillation (8 mBar, RT to max. bath temperature 80 °C) to give the crude product as a brownish liquid which can be used directly in the next synthesis step.

[0629] Step 1.4: Synthesis of bis(l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) 2-butylmalonate D

[0630]

[0631] Step 1.4: Synthesis of bis(l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) 2-butylmalonate D

[0632] Step 1.5: Synthesis of bis(l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) 2-{3-[2,5-bis({4-butyl-5-[(l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]-4-{[(l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)oxy]carbonyl}-5-oxopentyl})phenyl]propyl}-2-butylmalonate 1

[0633]

[0634] 0.31 g (7.80 mmol) of sodium hydride (60% suspension in paraffin oil) was suspended in 9.7 mL of N,N-dimethylformamide (DMF). A solution of 3.75 g (7.87 mmol) of diradical D dissolved in 29.0 mL of DMF was added dropwise under mild cooling (gas release), and the mixture was stirred at RT for 1 hour. 1.40 g (2.39 mmol) of triiodide B was added dropwise to the reaction solution (exothermic reaction at 5°C over 5 minutes), and the mixture was stirred at room temperature for 3 hours. The reaction mixture was carefully added to an ammonium chloride solution and extracted with MTBE. The phases were separated, the aqueous phase was extracted with MTBE, washed with saturated NaCl solution, dried over sodium sulfate, filtered, and evaporated under vacuum. The resulting orange crude product was filtered through silica gel with ethyl acetate / heptane (1:1), and the product fraction was evaporated under vacuum to give an orange solid that effervesced in a glassy manner. This product has the following properties.

[0635] Phase: Glass transition temperature (TG) = 23.5℃, decomposition begins at 150℃.

[0636] MS(APCI) = 1605.1[M+H + ].

[0637] Synthesis Example 2: Synthesis of bis(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl)2-(3-{3,5-bis[({4-butyl-5-[(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl)oxy]-4-{[(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl)oxy]carbonyl}-5-oxopentyl}oxy)carbonyl]benzoyloxy}propyl)-2-butylmalonate 2

[0638] (Material Example 2)

[0639]

[0640] Step 2.1: bis(1-oxy-2,2,6,6-tetramethylpiperidin-4-yl)2-butyl-2-[3-( Synthesis of alkyl-2-yloxy)propyl]malonate E

[0641]

[0642] Sodium hydride 3.20 g (80.4 mmol) (60% suspension in paraffin oil) was suspended in 30 ml DMF. A solution of 32.40 g (69.14 mmol) of the double radical D (from the synthesis of compound 1) in 300 ml DMF was added dropwise to the reaction solution under gentle cooling (gas evolution) and the mixture was stirred at room temperature for 1 h. Then a solution of 19.0 g (85.16 mmol) of 2-(3-bromopropoxy)tetrahydropyran in 200 ml DMF was added dropwise at RT (exotherm 0.5°C). To degas the reaction mixture before the temperature rises, a gentle stream of argon was passed through the reaction mixture for 30 min by means of an immersion Pasteur pipette and the mixture was then stirred at 35°C for 18 h. The reaction solution was allowed to cool to RT, was added to a saturated NaCI solution, was extracted with MTBE and the phases were separated. The aqueous phase was extracted with MTBE and the organic phases were combined, washed with a saturated NaCI solution, dried over sodium sulfate, filtered and evaporated in vacuo to give the crude product as a red oil which was filtered through silica gel with DCM / MTBE (9:1) in order to purify it, giving the product as a red oil.

[0643] Step 2.2: Synthesis of bis(l-hydroxy-2,2,6,6-tetramethylpiperidin-4-yl) 2-butyl-2-(3- hydroxypropyl)propanedioate F

[0644]

[0645] A mixture of 36.5 g (56.1 mmol) of the double radical E and 9.50 g (55.2 mmol) of toluene-4-sulfonic acid monohydrate was dissolved in a mixture of 500 ml methanol and 50 ml water and the mixture was stirred at 40°C for 5 h. The reaction solution was cooled to RT and was adjusted to pH = 9 using a NaHC03solution under cooling and was evaporated in vacuo. The aqueous residue was extracted with MTBE and the combined organic phases were washed with a saturated NaCI solution, dried over sodium sulfate, filtered and evaporated in vacuo to give a red oil which was dissolved in 250 ml DCM, 6.00 g (55.6 mmol) of Mn02was added and the mixture was stirred at RT for 1 h. (In the case of removal of the THP protecting group, the radical is also converted to the OH compound in some cases, which is reversed using Mn02). The reaction mixture was filtered through silica gel with DCM and evaporated in vacuo. The crude product obtained was filtered through silica gel with DCM / MTBE (7:3) and the product fractions were evaporated in vacuo to give a red oil.

[0646] Step 2.3: Synthesis of Bis(1 -oxy-2,2,6,6-tetramethylpiperidin-4-yl) 2-(3-{3,5-bis[({4-butyl-5-[(1 -oxy-2,2,6,6-tetramethylpiperidin-4-yl)oxy]-4-{[(1 -oxy-2,2,6,6-tetramethylpiperidin-4-yl)oxy]carbonyl}-5-oxopentyl}oxy)carbonyl]-benzoyloxy}propyl)-2-butyl propanoate 2

[0647]

[0648] A solution of 6.70 g (11.7 mmol F and 50.0 mg (0.41 mmol) 4-(dimethylamino)pyridine in 100 ml dichloromethane was cooled to 4°C at RT. Then 5.00 ml (36.1 mmol) triethylamine was added and subsequently a solution of 1.00 g (3.77 mmol) 1,3,5-benzotricarbonyl chloride in 10 ml DCM was added dropwise at 3-4°C. When the exotherm was completed, the mixture was allowed to warm to RT and subsequently stirred for 18 h at RT. Then a solution of ammonium chloride was added under cooling, the mixture was stirred briefly, the phases were separated and the aqueous phase was extracted with DCM. The combined organic phases were washed with a diluted NaCI solution (for better phase separation), dried over sodium sulfate, filtered and evaporated in vacuo to yield the reaction product as a red solidifying foam. For further purification, the product was filtered over silica gel with DCM / MTBE (9:1 to 85:15) and the product fractions were evaporated in vacuo. The resulting reaction product was a red solidifying foam. It had the following properties.

[0649] Phase: Tg (glass transition temperature) 52°C I, decomposition > 175°C.

[0650] MS (APCI) = 1734.

[0651] The following compounds were prepared analogously to one or more of the described synthesis sequences.

[0652] Material / Synthesis Example 3:

[0653]

[0654] Phase: Tg (glass transition temperature) -3°C I (isotropic), decomposition > 100°C.

[0655] Material / Synthesis Example 4:

[0656]

[0657] Phase: Tg (glass transition temperature) 5°C I (isotropic), decomposition > 180°C.

[0658] Material / Synthesis Example 5:

[0659]

[0660] Phase: Tg (glass transition temperature) 5°C I (isotropic), decomposition > 170°C.

[0661] Material / Synthesis Example 6:

[0662]

[0663] Phase: Tg (glass transition temperature) 27°C I (isotropic)

[0664] Material / Synthesis Example 7:

[0665]

[0666] Material / Synthesis Example 8:

[0667]

[0668] Phase: Tg (glass transition temperature) -3°C I (isotropic)

[0669] Material / Synthesis Example 9:

[0670]

[0671] Phase: Tg 22 K 112 I

[0672] Material / Synthesis Example 10:

[0673]

[0674] Phase: Tg -2 I.

[0675] Material / Synthesis Example 11:

[0676]

[0677] Mixture Examples

[0678] Example 1 and the corresponding comparative example

[0679] Liquid crystal mixtures having the compositions and properties shown in the table below were prepared and investigated. By comparison with the unstabilized base mixture as a reference, improved stability of the mixtures comprising the compounds of the formula I was shown.

[0680] The following mixture (M-1) was prepared and investigated

[0681]

[0682]

[0683] First, the stability of the voltage retention of the mixture (M-1 ) itself was determined. In test cells with a layer thickness of 6.0 pm of an alignment material for planar alignment and a flat ITO electrode, the stability of the mixture M-1 against backlight irradiation was investigated. For this purpose, one or more mixtures were subjected to a test of exposure to backlight. For this purpose, the stability of the respective test cell against backlighting with LEDs (light emitting diodes) for LCDs was investigated. For this purpose, the respective test cell was filled and sealed. These cells were then exposed to commercial LCD backlighting several times. In addition to the heat generated by the backlight, no additional heat was applied. The "voltage retention" was then determined after 5 minutes at a temperature of 100 °C in each case. The results are summarized in the following table, Table 1 a.

[0684] Here, six test cells were filled and investigated for each individual mixture as follows. The indicated values are the average of six individual values.

[0685] In the various measurement series, the relative deviation of the "voltage retention" values was generally in the range of about 3 to 4%.

[0686] Correspondingly, 100 ppm, 500 ppm or 1000 ppm of the reference compound R-1 were added to three further portions of the mixture M-1,

[0687]

[0688] and 100 ppm, 500 ppm or 1000 ppm of the compound R2 were added to three further portions of the mixture M-1,

[0689]

[0690] As described above, the stability of the resulting mixtures (C-1.1, C-1.2 and C-1.3 and M-1.1, M-1.2 and M-1.3) was investigated. The results are shown in the following tables, Tables 1 a to 1 c.

[0691] In addition to the compound of the formula I, the reference compound R-1 and a further reference compound R-3 have also been used here.

[0692] Table 6a

[0693]

[0694]

[0695] Example 2 and the corresponding comparative example

[0696] The following mixture (M-2) was prepared and investigated.

[0697]

[0698] First, the stability of the mixture (M-2) as such was determined. For this purpose, the stability of the mixture M-2 to backlit illumination was investigated in test cells with a layer thickness of 6.0 pm of an alignment material for planar alignment and a flat ITO electrode. For this purpose, one or more mixtures were subjected to a test of exposure to back light. For this purpose, the respective test cell was investigated for stability to LED (light emitting diode) back lighting for LCD. For this purpose, the respective test cell was filled and sealed. These test cells were then exposed to commercial LCD back lighting several times. In addition to the heat generated by the back light, no additional heat was applied. The "voltage retention" was then determined after 5 minutes at a temperature of 100 °C in each case.

[0699] Example 3 and the corresponding comparative example

[0700] The following mixture (M-3) was prepared and investigated.

[0701]

[0702]

[0703] The stability of the voltage retention of the mixture M-3 to UV radiation was investigated below. For this purpose, the mixture was also divided into several portions.

[0704] First, the stability of the mixture (M-3) as such was determined. For this purpose, the stability of the mixture M-3 to UV exposure was investigated in test cells with a layer thickness of 6.0 pm of a suitable polyimide as an alignment material for planar alignment and a flat ITO electrode. For this purpose, the respective test cell was irradiated in a Suntest for 30 minutes. The voltage retention was then determined after 5 minutes at a temperature of 100 °C in each case. The addressing frequency (or measurement frequency) here is 60 Hz unless otherwise specified in detail.

[0705] Example 4

[0706] The following mixture (M-4) was prepared and investigated.

[0707]

[0708]

[0709] As described in Examples 1 to 3, mixture M-4 was also divided into several portions and such studies were conducted as to its stability to exposure to LCD backlight and UV sources, as well as studies with various additive compounds, in test cells with planar alignment of the alignment material and planar ITO electrodes.

[0710] Example 5

[0711] The following mixture (M-5) was prepared and studied.

[0712]

[0713] As described in Examples 1 to 4, mixture M-5 was also divided into several portions and such studies were conducted as to its stability to exposure to LCD backlight and UV sources, as well as studies with various additive compounds, in test cells with planar alignment of the alignment material and planar ITO electrodes.

[0714] Example 6

[0715] The following mixture (M-6) was prepared and studied.

[0716]

[0717] As described in Examples 1 to 6, mixture M-6 was also divided into several portions and such studies were conducted as to its stability to exposure to LCD backlight and UV sources, as well as studies with various additive compounds, in test cells with planar alignment of the alignment material and planar ITO electrodes.

Claims

1. A liquid-crystalline medium, characterised in that comprising a) one or more compounds of the formula I in an amount of 1 ppm to 1500 ppm by weight, which compounds of the formula I are selected from the group of the compounds of the formulae I-1 to I-11 b) one or more compounds of the formula II in a total concentration of 1 % by weight or more to 90 % by weight or less and / or one or more compounds of the formula III in a total concentration of 1 % by weight or more to 40 % by weight or less, wherein R 2 H, an unfiuorinated or fluorinated alkyl group having 1 to 17 C atoms or an unfiuorinated or fluorinated alkoxy group, or an unfiuorinated or fluorinated alkenyl group, an unfiuorinated or fluorinated alkenyloxy group or an unfiuorinated or fluorinated alkoxyalkyl group having 2 to 15 C atoms, in which one or more CH2-groups can be replaced by instead, independently of each other at each occurrence represent in which R L identically or differently at each occurrence, denotes H or alkyl having 1 to 6 C atoms, L 21 and L 22 independently of one another H or F, X 2 represents F, Cl, -OCF3, -O-CH2CF3, -O-CH=CH2, -O-CH=CF2or -CF3, m denotes 0, 1, 2 or 3, R 3 represents H, an unfluorinated or fluorinated alkyl group having 1 to 17 carbon atoms or an unfluorinated or fluorinated alkoxy group, or an unfluorinated or fluorinated alkenyl group having 2 to 15 C atoms, an unfluorinated or fluorinated alkenyloxy group or an unfluorinated or fluorinated alkoxyalkyl group, in which one or more CH2-groups can be replaced by instead, independently of one another in each occurrence represent in which R L identically or differently at each occurrence, denotes H or alkyl having 1 to 6 C atoms; or L 31 and L 32 independently of one another H or F, X 3 represents F, Cl, -OCF3, -OCHF2, -O-CH2CF3, -O-CH=CF2, -O-CH=CH2or -CF3, Z 3 represents -CH2CH2-, -CF2CF2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CH2O- or a single bond, and n denotes 0, 1, 2 or 3.

2. Medium according to claim 1, characterized in that The total concentration of the compounds of the formula I in the entire medium is 100 ppm or more to 1500 ppm or less.

3. Medium according to claim 1 or 2, characterized in that which comprises one or more compounds of the formula II.

4. Medium according to claim 1 or 2, characterized in that which comprises one or more compounds of the formula III.

5. Medium according to claim 1 or 2, characterized in that which comprises one or more compounds selected from the group of the compounds of the formulae B and S wherein representing representing R B1 and R B2 independently of one another alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, wherein one -CH2- group can be replaced by cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, alkenyl having 2 to 7 carbon atoms, alkenyloxy, alkoxyalkyl or fluorinated alkenyl, wherein one -CH2- group can be replaced by cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, n denotes 0 or 1, representing representing R S1 and R S2 independently of one another alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy, wherein one -CH2- group can be replaced by cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, alkenyl having 2 to 7 carbon atoms, alkenyloxy, alkoxyalkyl or fluorinated alkenyl, wherein one -CH2- group can be replaced by cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, and n denotes 0 or 1.

6. Medium according to claim 1 or 2, characterized in that which comprises one or more compounds selected from the group of the compounds of the formulae IV and V wherein R 41 and R 42 each independently of one another have the meanings given above in claim 1 for R 2 each independently of one another have the meanings given above in claim 1 for R independently of each other and, if present, each independently of the other, have one of the meanings given in claim 1 for twice, these also independently of each other and, if present, each independently of the other, have one of the meanings given in claim 1 for given in claim 1, Z 41 and Z 42 independently of one another and, if Z 41 occur twice, these also independently of one another denote -CH2CH2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CH2O-, -CF2O-, -C≡C- or a single bond, and p denotes 0, 1 or 2, R 51 and R 52 each independently of one another have the meanings given for R 41 and R 42 each independently of one another have the meanings given for R to each independently of one another have one of the above given meanings for R1, Z 51 to Z 53 each, independently of one another, denotes -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, and i and j each, independently of one another, denote 0 or 1.

7. Medium according to claim 1 or 2, characterized in that which additionally comprises one or more chiral compounds.

8. An electro-optical display or electro-optical assembly, characterized in that, which contains a liquid-crystalline medium according to any of claims 1 to 7.

9. The display of claim 8, wherein, which is based on the IPS, FFS, VA or ECB effect.

10. The display of claim 8 or 9, wherein, which comprises an active matrix addressing device.

11. Use of a liquid-crystalline medium according to any of claims 1 to 7 in an electro-optical display or an electro-optical component.

12. The method of producing a liquid-crystalline medium according to any of claims 1 to 7, characterised in that one or more compounds of the formula I according to claim 1 are mixed with one or more compounds of the formula II according to claim 1 and / or one or more compounds selected from the group of the compounds of the formula III according to claim 1.

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