Liquid crystal compounds

Abstract

The invention relates to novel compounds and mixtures thereof, which are capable of forming a ferroelectric nematic liquid-crystalline phase at ambient temperature. The compounds of the formula I are shown below wherein the variable groups have the meanings indicated in claim 1. The liquid-crystalline medium comprises at least one compound of the formula I.

Description

[0001] One aspect of the present invention relates to a compound of formula I as defined below, which maintains a ferroelectric nematic liquid crystal phase. Furthermore, the present invention includes liquid crystal media comprising at least one compound of formula I, and its use as a component in liquid crystal media. Furthermore, the present invention relates to liquid crystal displays and electro-optical elements containing liquid crystal compounds and media according to the present invention.

[0002] Over the past few years, the application fields of liquid crystal compounds have expanded significantly to various types of display devices, electro-optical devices, electronic components, sensors, and more. As a result, many different structures have been proposed, particularly in the field of nematic liquid crystals. To date, nematic liquid crystal mixtures have the widest application in flat panel display devices. They have been specifically used in passive TN or STN matrix displays or systems with TFT active matrices, including well-known TN, IPS, FFS, and VA systems.

[0003] Most of these devices employ a nematic liquid crystal phase, including all common LCD televisions, LCD desktop monitors, and mobile LCD devices. Some alternative liquid crystal phases are known, such as ferroelectric smectic phases or blue phases. However, ferroelectric nematic phases (N... f The ferroelectric nematic phase (LC phase) has only been proposed theoretically for decades, and no suitable liquid crystal material with this property has been found. Only recently have two chemical structures with ferroelectric nematic behavior been proposed.

[0004] Hiroya Nishikawa, Kazuya Shiroshita, Hiroki Higuchi, Yasushi Okumura, Yasuhiro Haseba, Shin-ichi Yamamoto, Koki Sago and Hirotsugu Kikuchi, Adv. Mater. 2017, 29, 1702354 describes compounds of formula A as exhibiting ferroelectric nematic behavior at temperatures ranging from about 45 °C to 68 °C.

[0005]

[0006] In addition, Nerea Sebastián, Luka Cmok, Richard J. Mandle, María Rosario de la Fuente, Irena Olenik, Martin Alenka Mertelj, Physical Review Letters (2020) 124, 037801, describes a compound of formula B that exhibits similar behavior between approximately 120 °C and 133 °C.

[0007]

[0008] Xi Chen et al., PNAS June 23, 2020 117(25)14021-14031 proposed two unique methods applicable to N f Further comparisons of the substances in the -LC phase. The new N is highlighted in Od Lavrentovic, Proc Nat Acad Sci USA (2020), 117(26), 14629-14631. f The high importance of the appearance of the -LC phase.

[0009] To date, no ferroelectric nematic liquid crystal phase (N1) with near-room temperature has been described. f Liquid crystal compounds (LC phase). N f -LC phases will significantly benefit from adaptability to ambient temperatures in technical applications. Display applications are typically designed to operate over both above and below room temperature, for example, 0 to 50°C, with higher temperatures being preferred.

[0010] Ferroelectric nematic displays were proposed in DE19629551A1, but no materials that could satisfy the required ferroelectric nematic properties were mentioned.

[0011] The use of fluorinated liquid crystal materials is known to those skilled in the art. Various compounds containing two 2,6-difluorinated 1,4-phenylene rings have been described as liquid crystal or mesocrystalline materials, for example in publication text WO 2015 / 101405 A1 and various other publications. The compounds presented therein do not contain three 2,6-difluorinated phenylene rings and bridging groups of the same pattern, such as C(O)O or CF2O, nor have they been reported to possess any ferroelectric properties.

[0012] One object of this invention is to find a suitable medium for ferroelectric nematic liquid crystals (N... f A novel stable compound consisting of a single compound or component in an LC phase medium. In particular, the compound should simultaneously possess N... f -LC phase or N f Such phases are supported in LC media. They should also have moderate to high optical anisotropy to achieve the same electro-optical switching effects as conventional nematic LC media.

[0013] Considering the very wide range of applications for this type of compound with high Δε, it is desirable to have other available compounds, preferably with high-definition bright spots and low melting points, while exhibiting a wide and suitable temperature range for the ferroelectric nematic phase.

[0014] Therefore, another object of the present invention is to find novel stable compounds suitable as components of ferroelectric nematic liquid crystal media, particularly for displays similar to conventional nematic TN, STN, IPS, FFS and TN-TFT displays.

[0015] Furthermore, the compounds according to the invention are intended to be thermally and photochemically stable under the dominant conditions in the application field. As mesocrystalline, they should promote a broad mesocrystalline phase in mixtures with liquid crystal cocomponents and be readily miscible with mesocrystalline-based mixtures, especially at room temperature or lower.

[0016] Surprisingly, the compounds according to the present invention have been found to be highly suitable as N f - LC media composition. Ferroelectric nematic phases can be realized within a favorable temperature range (at or near ambient temperature). This significantly broadens the library of compounds exhibiting ferroelectric nematic phases that are so unusual to date. They can be used to obtain liquid crystal media for displays that require particularly high or even extremely high dielectric anisotropy, especially for IPS or FFS displays, and for TN or STN displays. The compounds according to the invention are sufficiently stable and colorless. In particular, they are characterized by very high dielectric anisotropy (Δε), thus requiring much lower threshold voltages when used in optical switching elements. They have fairly good solubility for compounds with comparable properties and can be mixed with an almost unlimited number of similar compounds. Furthermore, the compounds according to the invention have high-definition bright spots. The compounds have low melting points or can remain stably below their melting points as supercooled melts, which makes it possible to form the desired N at room temperature and below. f -LC phase.

[0017] From various application perspectives, the compounds provided according to the present invention can very generally and significantly broaden the range of liquid crystal materials applicable to the preparation of ferroelectric nematic liquid crystal mixtures.

[0018] The compounds according to the invention have a wide range of applications. Depending on the choice of substituents, these compounds can be used as base materials that mainly constitute liquid crystal media. However, liquid crystal base materials from other classes of compounds can also be added to the compounds of formula I according to the invention to, for example, further reduce the melting point, affect the dielectric and / or optical anisotropy of such dielectrics and / or optimize their threshold voltage and / or viscosity.

[0019] Using the compounds of this invention results in LC dielectrics with extremely short response times compared to conventional nematic LC systems currently used in standard displays. This invention itself can improve the way moving images are displayed. The high dielectric constant is also of interest for dielectrics in capacitors.

[0020] The liquid crystal compounds according to the present invention can be used as components of liquid crystal media, particularly for displays based on principles of twisted cell, guest-host effect, alignment phase deformation effect DAP or ECB (electrically controlled birefringence), IPS (in-plane switching) effect or dynamic scattering effect.

[0021] Therefore, this invention relates to compounds of formula I.

[0022]

[0023] in

[0024] X 1 For CN, F, CF3, OCF3, SCN, NCS, SF5, or O-CF=CF2,

[0025] Z 1 It is -C(O)O- or -CF2O-, and

[0026] L 1 It can be H or CH3, preferably H.

[0027] R 1 This indicates an alkyl group having 1 to 15 carbon atoms, wherein, in addition, one or more CH2 groups (including any terminal carbon) in these groups can be independently coupled to each other in a manner in which the O / S atoms are not directly connected to each other, such as -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -S-, -CO-O-, or -O-CO- can be substituted, and additionally, one or more H atoms may be substituted with halogens, or represent H.

[0028] Preferably, R 1 It is a haloalkanes or unsubstituted alkyl groups having 1 to 15 carbon atoms, wherein, in addition, one or more CH2 groups in these groups may be independently replaced by -C≡C- or -CH=CH- in each case.

[0029] The present invention also relates to the use of compounds of formula I in liquid crystal media.

[0030] The present invention also relates to liquid crystal media comprising at least one, preferably two, three, four or more compounds of Formula I and any optional additives.

[0031] In its pure state, the compound of formula I is colorless and, either alone or in a mixture, forms a liquid crystal mesocrystalline phase within a temperature range favorable for electro-optical applications. The compounds according to the invention also support N... f- The nematic phase range outside the phase range. In liquid crystal mixtures, the substances according to the invention significantly increase optical anisotropy. Simultaneously, the compounds are characterized by good UV stability.

[0032] Group R in Formula I and its sub-formulas 1 Preferably, it represents an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or an alkenyl group having 2 to 8 carbon atoms. The alkyl chain is preferably straight-chain or branched by a single methyl or ethyl substituent, preferably at the 2- or 3-position. R 1 Particularly preferred are straight-chain alkyl groups having 1-7 carbon atoms or unbranched alkenyl groups having 2-8 carbon atoms, especially unbranched alkyl groups having 1-5 carbon atoms.

[0033] Preferred alternative group R 1 It is selected from cyclopentyl, 2-fluoroethyl, cyclopropylmethyl, cyclopentylmethyl, cyclopentylmethoxy, cyclobutylmethyl, 2-methylcyclopropyl, 2-methylcyclobutyl, 2-methylbutyl, 2-ethylpentyl and 2-alkoxyethoxy.

[0034] Group X of Formula I 1 The preferred expression is CN, F or CF3, more preferably CN or F, and most preferably CN.

[0035] Contains branched or substituted side groups R 1 Compounds of formula I can sometimes be important because they exhibit better solubility in conventional liquid crystal base materials. Group R 1 Preferably, it is a straight chain (unbranched).

[0036] Group R 1 The preferred selections are from the following:

[0037] H

[0038] CH3

[0039] C2H5

[0040] n-C3H7

[0041] n-C4H9

[0042] n-C5H 11

[0043] C2H5CH(CH3)CH2

[0044] n-C6H 13

[0045] n-C7H 15

[0046] n-C3H7CH(C2H5)CH2

[0047] n-C8H 17

[0048] c-C3H5

[0049] c-C3H5CH2

[0050] c-C4H7

[0051] c-C5H7

[0052] c-C5H9

[0053] c-C5H9CH2

[0054] CH2=CH

[0055] CH3CH=CH

[0056] CH2=CH(CH2)2

[0057] CH3O

[0058] C2H5O

[0059] n-C3H7O

[0060] n-C4H9O

[0061] and

[0062] n-C5H 11 O

[0063] The following end-base abbreviations are used in the context:

[0064] c-C3H5

[0065] c-C3H5CH2

[0066] c-C4H7

[0067] c-C5H7

[0068] c-C5H9

[0069] c-C5H9CH2

[0070] Particularly preferred compounds of formula I are compounds of formulas I-1 to I-20:

[0071]

[0072]

[0073]

[0074]

[0075] The particularly preferred compounds have the following formula:

[0076]

[0077] Where R 1 As defined for Equation I or according to its more detailed specific definition.

[0078] Compounds of Formula I can be prepared by methods known per se, as described in the literature (e.g., in standard works such as Houben-Weyl, Methodden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), specifically under known and suitable reaction conditions. Variations known per se, which are not discussed in more detail herein, may also be used.

[0079] The compounds of Formula I can be advantageously prepared as shown in the following illustrative synthesis and examples (Schemes 1 to 2):

[0080]

[0081] Scheme 1. Preparation of compound I (Z) 1 The general synthesis scheme for =-C(O)O-). R 1 L 1 and X 1 As defined in Equation I.

[0082] In Synthesis Scheme 2, this paper presents an alternative reaction route for the preparation of the corresponding difluoromethoxy compounds.

[0083]

[0084] Scheme 2. General synthetic scheme for preparing compound I, wherein Z 1 =-CF2O-. R 1 L 1 and X 1 As defined in Equation I.

[0085] The corresponding starting materials can usually be readily prepared by those skilled in the art using synthetic methods known in the literature or are commercially available.

[0086] The reaction methods and reagents used are, in principle, known from the literature. Further reaction conditions are illustrated by working examples. Other preferred variations of the method (not mentioned above) are disclosed by examples.

[0087] The method and subsequent treatment of the reaction mixture obtained by the above method can be carried out substantially as a batch reaction or in a continuous reaction process. Continuous reaction processes include, for example, reactions in a continuous stirred tank reactor, a cascade of stirred tank reactors, a loop or cross-flow reactor, a flow tube, or a microreactor. Depending on the need, treatment may optionally be carried out by solid-phase filtration, chromatography, separation between immiscible phases (e.g., extraction), adsorption onto a solid support, removal of solvents and / or azeotropic mixtures by distillation, selective distillation, sublimation, crystallization, co-crystallization, or by nanofiltration over a membrane.

[0088] The present invention also relates to a liquid crystal medium comprising one or more compounds of Formula I according to the invention. The liquid crystal medium preferably comprises at least two components, each preferably having a ferroelectric nematic phase. They are preferably obtained by mixing the components with each other, preferably by heating to above the melting point of one or more compounds.

[0089] Therefore, the method for preparing a liquid crystal medium according to the present invention is characterized by mixing at least one compound of formula I with at least one other, preferably mesocrystalline, more preferably ferroelectric nematic compound, and optionally adding additives. A preferred method for preparing a liquid crystal medium includes mixing at least two or more compounds of formula I as defined herein, while optionally adding other compounds and additives before or after the mixing.

[0090] The achievable combination of temperature range, clearing point, dielectric anisotropy, and response time of the ferroelectric nematic phase in liquid crystal media containing Formula I compounds is far superior to that of prior art materials of this type. Previously, only single compound materials with limited selection were available, none of which exhibited a ferroelectric nematic phase range at suitable temperatures. The liquid crystal medium according to the invention exhibits a ferroelectric nematic phase over a wide temperature range, and it falls within the range of most technically interesting approximately 20°C, i.e., ambient temperatures from approximately 0°C to 50°C.

[0091] The liquid crystal medium according to the present invention may preferably contain compounds of formula I 2, 3, 4 or more. It was found in the group R... 1 Mixtures of homologues with varying properties can still support the ferroelectric nematic sequence of phases, and even extend the temperature range at both ends, i.e., at lower and higher temperatures. In the prior art, such mixtures of several mesomorphic compounds typically only provide extended nematic or smectic phases. In a preferred embodiment, the liquid crystal medium comprises two, three, or more compounds of formula I. By combining several compounds of formula I, the melting point can be lowered and the N-phase of the resulting LC medium can be broadened.f Phase range.

[0092] Further research based on these findings indicates the existence of even more compounds supporting the ferroelectric nematic phase. These are preferably selected from compounds having a ferroelectric nematic phase or compounds that support such a phase in mixtures with or with compounds of Formula I. In this embodiment, the compounds of the present invention are mixed with these additional compounds to obtain an alternative liquid crystal medium. Preferably, the liquid crystal medium still comprises at least 5% by weight, at least 10%, at least 20%, more preferably 40% or more, and most preferably 55% or more of one or more compounds of Formula I.

[0093] The liquid crystal medium according to the invention may preferably contain 1-40, particularly 4-20, components as other components besides one or more compounds according to the invention. Specifically, these media may contain 1-10 components besides one or more compounds according to the invention. These other components are preferably selected from ferroelectric nematic or nematic (unidirectional or isotropic) materials.

[0094] Existing ferroelectric materials and similar compounds with high dielectric anisotropy for use in combination with current materials are selected from, for example, the following structures:

[0095]

[0096] More generally, compounds of formula II

[0097]

[0098] in

[0099] R 2 It is an alkyl group having 1 to 15 carbon atoms, wherein, in addition, one or more CH2 groups (including any terminal carbon) in these groups can be independently converted to each other by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -S-, -CO-O-, or -O-CO- are substituted in such a way that the O / S atoms are not directly connected to each other, and in addition, one or more H atoms can be substituted with halogens, or represent H.

[0100] Z 2 Z 3 Each is independently a single bond, -C(O)O-, or -CF2O-, with Z being the preferred choice. 2 and Z 3 One of them is a single key.

[0101] L 2 It is H or CH3.

[0102] L 3 ,L 4 Independently, it is either F or H, with F preferred.

[0103] X 2 The components are CN, F, CF3, OCF3, or SCN, with F or CN being preferred.

[0104] A 2 for

[0105] p is 0 or 1,

[0106] Furthermore, compounds of formula I are excluded from compounds of formula II.

[0107] An exemplary preferred compound of formula II is

[0108]

[0109]

[0110] Where n is 0, 1, 2, 3, 4, 5, 6, 7, etc.

[0111] The medium according to the invention preferably contains 1 to 100%, more preferably 10 to 100%, and even more preferably 20%, 30%, 40%, 50%, 60%, 70% or more of the compound of formula I according to the invention.

[0112] The liquid crystal mixtures according to the invention are prepared in a conventional manner. Typically, the required amount of the component used in a small quantity is dissolved in the component constituting the main component, preferably at an elevated temperature. The solutions of the components in organic solvents (e.g., acetone, chloroform, or methanol) can also be mixed, and the solvent is removed again after thorough mixing, for example, by distillation. Furthermore, the mixtures can be prepared in other conventional ways, such as using premixes, homologue mixtures, or using a so-called "multi-bottle" system.

[0113] The liquid crystal mixture may also contain other additives known to those skilled in the art and described in the literature. For example, 0 to 15%, preferably 0 to 10%, of pleochroic dyes, chiral dopants, stabilizers, or nanoparticles may be added. The individual compounds are used at a concentration of 0.01 to 6%, preferably 0.1 to 3%. However, concentration data for other components of the liquid crystal mixture (i.e., liquid crystals or mesocrystalline compounds) are given herein without regard to the concentrations of these additives. The liquid crystal mixture according to the invention significantly broadens the range of usable parameters.

[0114] The present invention also relates to electro-optic displays (particularly TFT displays having two planar parallel outer plates (which together with a frame form a cell), integrated nonlinear elements for switching individual pixels on the outer plates, and a nematic liquid crystal mixture having positive dielectric anisotropy and high specific resistance located in the cell), and the use of these media for electro-optic purposes.

[0115] The term "alkyl" includes unbranched and branched alkyl groups having 1-15 carbon atoms, particularly and preferably unbranched groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, and n-heptyl, and further includes n-butyl, n-pentyl, and n-hexyl groups substituted with one methyl, ethyl, or propyl group. Groups having 2-5 carbon atoms are generally preferred.

[0116] The term "alkenyl" includes both unbranched and branched alkenyl groups having up to 15 carbon atoms, particularly unbranched groups. Particularly preferred alkenyl groups are C2-C7-1 E-alkenyl, C4-C7-3 E-alkenyl, C5-C7-4-alkenyl, C6-C7-5-alkenyl, and C7-6-alkenyl, especially C2-C7-1 E-alkenyl, C4-C7-3 E-alkenyl, and C5-C7-4-alkenyl. Examples of preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl, etc. Groups with 2-5 carbon atoms are generally preferred.

[0117] The expression "halogenated alkyl" preferably includes mono- or polyfluoro and / or chlorinated groups. Perhalogenated groups are included. Fluorinated alkyl groups are particularly preferred, especially CF3, CH2CF3, CH2CHF2, CHF2, CH2F, CHFCF3, and CF2CHFCF3. The expression "halogenated alkenyl" and related terms are interpreted accordingly.

[0118] The total amount of the compound of formula I in the mixture according to the invention is not critical. Therefore, the mixture may contain one or more other components for optimization of various properties.

[0119] The matrix display according to the invention, consisting of a polarizer, an electrode substrate, and surface-treated electrodes, corresponds to the typical design of this type of display. The term "typical design" is interpreted broadly herein and includes all derivatives and modifications of matrix displays, particularly matrix display elements based on poly-Si TFTs.

[0120] However, the essential difference between the display according to the present invention and conventional displays based on twisted nematic elements to date lies in the selection of liquid crystal parameters of the liquid crystal layer.

[0121] The following embodiments illustrate the invention but are not intended to limit it. Those skilled in the art will be able to extract working details from the embodiments that are not given in detail in the general description, summarize them based on general professional knowledge, and apply them to specific problems.

[0122] In this context, percentage data represent weight percentages. All temperatures are expressed in degrees Celsius. Furthermore, C = crystalline, N = nematic phase, Sm = smectic phase (more specifically SmA, SmB, etc.), Tg = glass transition temperature, and I = isotropic phase. Data between these symbols represent transition temperatures. Δn indicates optical anisotropy (589 nm, 20 °C), and Δε indicates dielectric anisotropy (1 kHz, 20 °C).

[0123] Physical, physicochemical, and electro-optical parameters are determined by commonly known methods, such as those described in the handbook "MerckLiquid Crystals - -Physical Properties of Liquid Crystals -Description of the Measurement Methods", 1998, Merck KGaA, Darmstadt.

[0124] The presence of ferroelectric nematic phases in materials is identified by observing the texture under a polarizing microscope equipped with a hot stage for controlled cooling or heating using differential scanning calorimetry (DSC), and further confirmed by the temperature dependence of dielectric properties.

[0125] The conventional dielectric anisotropy Δε of each substance was determined at 20 °C and 1 kHz. For this purpose, 5–10 wt% of the analyte was dissolved in a dielectric positive mixture ZLI-4792 (MerckKGaA), and the measurements were extrapolated to a 100% concentration. The optical anisotropy Δn was determined at 20 °C and a wavelength of 589.3 nm, and the rotational viscosity γ1 was determined at 20 °C, both using linear extrapolation.

[0126] The dielectric constant of the pure compound was determined directly by measuring the capacitance of at least one test cell containing the compound and having a cell thickness of 25 μm, with vertical and uniform orientation. Temperature was controlled using a Novocontrol NovoCool system set to apply temperature gradients of + / -1 K / min; + / -2 K / min; + / -5 K / min; + / -10 K / min to the sample cell. Capacitance was measured at a frequency of 1 kHz using a Novocontrol alpha-N analyzer, with typical voltages <50 mV to 0.1 mV to ensure below the threshold of the compound under study. Measurements were performed while heating and cooling the sample.

[0127] In this application, unless otherwise expressly stated, the plural form of a term refers to both the singular and plural forms, and vice versa. Further combinations of embodiments and variations of the invention according to the specification also derive from the appended claims or combinations of several of these claims. Example

[0128] The invention is described in detail below with reference to the following non-limiting embodiments.

[0129] Example 1: Synthesis of UUQU-4-N

[0130]

[0131] Step 1.1

[0132]

[0133] 20.3 mL (203 mmol) of 1,3-propanedithiol was dissolved in 25.9 mL of toluene and heated to 80 °C. A solution of 34.5 g (135.1 mmol) of 3, 0.2 mL of trifluoromethanesulfonic acid, and 40 mL of toluene was prepared and added dropwise to the dithiol solution at 80 °C. After the addition was complete, the mixture was stirred at 80 °C for 45 minutes and then cooled to 20 °C. 17.7 mL (200 mmol) of trifluoromethanesulfonic acid was added dropwise over 80 minutes, keeping the temperature below 25 °C. The toluene was distilled off at 80 °C and 40 mbar, and then 25 mL of toluene was added, and all volatiles were distilled off again. The crystalline residue was used for the next step without further purification.

[0134] Step 1.2

[0135]

[0136] 93.1 g (0.6 mol) of salt 5 was suspended in 1.6 L of dichloromethane and cooled to 6 °C. 83.2 mL (0.6 mol) of triethylamine was added dropwise at 5 °C, followed by 230 g (0.5 mol) of salt 4. The mixture was stirred at 5 °C for 30 minutes, then cooled to -75 °C and 244.3 mL (1.5 mol) of triethylamine trihydrofluoride was added dropwise. The solution was stirred at -75 °C for one hour, and 128 mL (2.5 mol) of bromine dissolved in 400 mL of dichloromethane was added. The mixture was stirred at -70 °C for 1.5 hours and then warmed to 0 °C. After routine post-treatment, 132 g (62%) of salt 6 was obtained as light beige crystals.

[0137] Step 1.3

[0138]

[0139] 13.8 g (35 mmol) of 6 was dissolved in 150 mL of 1,4-dioxane, and 1.0 g (1.4 mmol) of palladium acetate, 10.4 g (0.1 mol) of potassium acetate, and 13.9 g (53 mmol) of bis(pinacolato)boron were added. The mixture was refluxed and heated overnight. After routine post-treatment, 12.4 g (80%) of 7 was obtained as pale yellow crystals.

[0140] Step 1.4

[0141]

[0142] Dissolve 5.4 g (23 mmol) of potassium phosphate in 10 ml of water. Add 80 ml of toluene, 2.8 g (11.4 mmol) of 1-bromo-2,6-difluoro-4-butylbenzene, 6.3 g (14.2 mmol) of 7, 42.2 mg (0.2 mmol) of palladium acetate, and 126.7 mg (0.3 mmol) of S-Phos (2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl). Reflux the mixture overnight. After standard treatment, 3.42 g (62%) of 9 (UUQU-4-N) was obtained as colorless crystals.

[0143] 1 ¹H NMR (400MHz, chloroform-d) δ 7.16 (d, J = 11.0 Hz, 2H), 7.07–6.99 (m, 2H), 6.91–6.81 (m, 2H), 2.69–2.61 (m, 2H), 1.69–1.57 (m, 2H), 1.39 (h, J = 7.4 Hz, 2H), 0.96 (t, J = 7.3 Hz, 3H).

[0144] Melting point: 44℃

[0145] Clearance: 21℃

[0146] Δn(20℃)=0.12

[0147] Characterization of ferroelectric-nematic behavior:

[0148] C 44 N f (21.4)I

[0149] The dielectric properties were also measured.

[0150] Table. Measurement of ε at different temperatures (cooling 1°C / min, flat metal electrode)

[0151] 5.0 2.34 Crystallization upon cooling 7.0 7,730 10.0 11,300 12.0 13,800 14.0 16,500 16.0 19,100 18.0 21,500 19.8 23,100 <![CDATA[ε max .]]> 20.0 22,800 20.5 2.39 <![CDATA[transform N f –isotropic]]> 21.0 2.39 22.0 2.40

[0152] Example 2: Synthesis of UUZU-4-N

[0153]

[0154] Step 2.1

[0155]

[0156] Step 2.2

[0157] 57.2 g (150 mmol) disodium tetraborate decahydrate, 2.8 g (4 mmol) palladium chloride, 0.2 g (4 mmol) hydrazine hydroxide, 39.4 g (0.2 mol) 1-bromo-3,5-difluorobenzene, 42.8 g (0.2 mol) of 10 and 200 ml of water were mixed. The mixture was heated to reflux for 6 hours. After routine post-treatment, 50 g (88%) of 11 was obtained.

[0158]

[0159] Step 2.3

[0160] 50 g (175 mmol) of lithium I1 was dissolved in 300 mL of tetrahydrofuran and cooled to -75 °C. 118 mL (193 mmol) of a 15% n-butyllithium solution in hexane was added dropwise below -70 °C, and the mixture was stirred at this temperature for 1.5 hours. The mixture was poured over 500 g of solid carbon dioxide and warmed to room temperature. After standard treatment, 46.8 g (82%) of lithium I2 was obtained as colorless crystals.

[0161]

[0162] Step 2.4

[0163] 16.3 g (50 mmol) of 12, 8.5 g (55 mmol) of 1-cyano-2,6-difluoro-4-hydroxybenzene, and 611 mg (5 mmol) of 4-dimethylaminopyridine were mixed with 200 mL of dichloromethane and cooled to 0 °C. At 0–5 °C, a solution of 11.3 g (55 mmol) of N,N-dicyclohexylcarbodiimide in 50 mL of dichloromethane was added dropwise. The mixture was then warmed to room temperature and stirred overnight. 1.4 g of oxalic acid was added, and all substances were stirred for another 1.5 hours. After standard treatment, 20.5 g (88%) of 13 (UUZU-4-N) was obtained.

[0164] 1 ¹H NMR (500MHz, chloroform-d) δ 7.23–7.17 (m, 2H), 7.15–7.08 (m, 2H), 6.91–6.83 (m, 2H), 2.69–2.62 (m, 2H), 1.69–1.59 (m, 2H), 1.39 (h, J = 7.4Hz, 2H), 0.96 (t, J = 7.4Hz, 3H).

[0165] Phase: K 69N f 92N 93I

[0166] Δn(20℃): 0.16

[0167] Example 3: Synthesis of UUZU-5-N

[0168]

[0169] The compound was prepared in a manner similar to that of Example 2.

[0170] Melting point: 80℃

[0171] Δn(20℃): 0.16

[0172] Similar to Examples 1 and 2, the following compounds were prepared:

[0173] In the table below, the following end-base abbreviations are used:

[0174]

[0175] general formula

[0176] Table. Examples of other compounds

[0177]

[0178]

[0179] Mp: Melting point.

[0180] Mixture Examples

[0181] Mixture Example 1

[0182] Liquid crystal media using the compounds according to the present invention are prepared as follows.

[0183] Prepare and study the following mixture.

[0184]

[0185] Mixture M-1 exhibits a ferroelectric nematic phase from 77°C to 31°C (when cooled).

[0186] Mixture Example 2

[0187]

[0188] The mixture M-2 exhibits a ferroelectric nematic phase.

[0189] Mixture Example 3

[0190]

[0191] The mixture M-3 exhibits a ferroelectric nematic phase.

[0192] Mixture Example 4

[0193]

[0194] The mixture M-4 exhibits a ferroelectric nematic phase.

[0195] Mixture Example 5

[0196]

[0197] Mixture M-5 exhibits a ferroelectric nematic phase below 38°C.

[0198] Mixture Example 6

[0199]

[0200] Mixture M-6 exhibits a ferroelectric nematic phase below 73°C.

[0201] Further combinations of embodiments and variations of the present invention are also disclosed in the claims.

[0202] Without further detailed explanation, it is believed that those skilled in the art can utilize the invention to its fullest extent using the foregoing description. Therefore, the foregoing preferred embodiments are merely illustrative and not intended to limit the remainder of this disclosure in any way. The foregoing embodiments can be similarly and successfully replicated by replacing the reactants and / or operating conditions used in the foregoing examples with those generally or specifically described in this invention.

[0203] From the foregoing description, those skilled in the art can readily identify the essential features of the invention, and various changes and modifications can be made to adapt it to various uses and conditions without departing from its spirit and scope.

Claims

1. A ferroelectric nematic liquid crystal medium comprising at least one compound of formula I, in X 1 Indicates CN, Z 1 It represents -C(O)O- or -CF2O-. L 1 It is H or CH3. R 1 It indicates a straight-chain alkyl group having 1-7 carbon atoms or an unbranched alkenyl group having 2-8 carbon atoms.

2. The liquid crystal medium according to claim 1, wherein Z 1 It represents -C(O)O-.

3. The liquid crystal medium according to claim 1, wherein Z 1 It represents -CF2O-.

4. The liquid crystal medium according to any one of claims 1 to 3, wherein R 1 It contains 2 to 7 carbon atoms.

5. The liquid crystal medium according to claim 1, wherein the compound of formula I is selected from compounds of the following formula: 。 6. The liquid crystal medium according to any one of claims 1 to 3, comprising at least 20% by weight or more of one or more compounds of formula I.

7. Use of one or more compounds of Formula I as defined in any one of claims 1 to 6 as components in a ferroelectric nematic liquid crystal medium.

8. A method for preparing a liquid crystal medium according to any one of claims 1 to 6, comprising mixing at least one compound of formula I with at least one other compound, and optionally adding an additive.

9. The method of claim 8, wherein the additional compound is a mesocrystalline compound.

10. The method of claim 8, wherein the additional compound is a ferroelectric nematic compound.

11. Use of the liquid crystal medium according to any one of claims 1 to 6 for electro-optical purposes.

12. An electro-optic liquid crystal display comprising a liquid crystal medium according to any one of claims 1 to 6.

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