Compounds and liquid crystal compositions

Abstract

This invention provides a ferroelectric liquid crystal (FLC) material for a deformable helical ferroelectric liquid crystal (DHFLC) electro-optic mode device. The FLC material exhibits optimal electro-optic properties, including high tilt angle (>38°), short pitch (<120 nm), and spontaneous polarization (>100 nC / cm). 2 The FLC material comprises at least two components, wherein at least one FLC component is a chiral compound of formula (I), particularly a chiral compound of formula (****), wherein W1 and W2 are chiral groups having polar substituents at the chiral center, and A and B are independently N atoms or CH groups, provided that at least one of A or B is an N atom. Other various groups are as defined herein.

Description

[0001] Citation of relevant applications

[0002] This application claims priority to U.S. Provisional Utility Model Patent Application No. 63 / 307,611, filed February 7, 2022, with the United States Patent and Trademark Office, the disclosure of which is hereby incorporated by reference. Technical Field

[0003] This disclosure generally relates to ferroelectric liquid crystal (FLC) materials for use in deformable spiral ferroelectric liquid crystal (DHFLC) electro-optic mode devices. Background Technology

[0004] Recent trends in the display and photonics industries demand high-speed electro-optic modulation of light in terms of amplitude, phase, or both of the incident light [1-7]. Fast electro-optic amplitude modulation is ideal for high-efficiency field-sequential color displays, augmented reality / virtual reality headsets, 3D cinemas, and the like. However, holographic displays, photonics, telecommunications, and optical switches require fast phase modulation. Fast phase modulation is also important for field-sequential color displays, as it can reduce power consumption by at least 3 times [1,3,5]. For these high-resolution devices, it is important to have a fast response time while displaying small drive voltages [8,9]. Although nematic liquid crystals are widely used as working media for display and photonic applications, their performance is limited by their sub-millisecond response times given the current demand for fast switching. In this regard, ferroelectric liquid crystals (FLCs) are a good option. The presence of spontaneous polarization indicates fast response times even at small drive voltages, and therefore FLCs have been extensively studied [1,4].

[0005] FLC is a chiral, tilted smectic LC (SmC*), comprising molecules arranged in layers (smectic layers), wherein they are tilted in one direction at a specific angle (tilt angle θ) within the layers. The tilted molecules form induced supramolecular helices from one layer to another, with their axes perpendicular to the interlayer boundaries. The distance required for the tilted molecule to complete one full rotation within the layer is called the pitch (p0), which can have two signs. Each layer has a dipole moment oriented perpendicular to the tilt plane (the plane defined by the molecular long axis and its projection onto the interlayer boundaries); due to chirality, P... S It can also have two signs. Enantiomers (fully mirror-image isomers of chiral molecules) are induced to have p0 and p with opposite signs. S Enantiomers of different chemical formulas can possess p0 and p2. S Any of the four combinations, depending on the specific chemical structure of the chiral molecule chosen. When two or more different chiral compounds are used in FLC, the 1 / p0 and P... SFollow the law of addition in the first approximation, that is, they are summed proportionally according to concentration and sign. The helix can be unwound by some external factors, such as an external electric field, interaction with the boundary surface, or their combination, etc.

[0006] The electro-optic operation of FLC can be divided into two basic types, namely with or without a helix. Surface stabilized FLC (SSFLC) and bistable FLC are electro-optic modulations without a helix, where the helix is either suppressed by interaction with the boundary surface or compensated by using chiral components with opposite twist signs ((1 / p0). When p0 >> d (where d is the cell gap), the helix suppression is more easily achieved. On the other hand, electro-optic (EO) modulations with a helix can be further divided into two subclasses: (a) when the helix is always present during the entire electro-optic operation, such as in a planar-aligned helical deformation type ferroelectric LC (DHFLC) or the Kerr effect (DHFLC in the case of vertical alignment), and (b) where the helix is present without an electric field and unwinds in the presence of a sufficiently large electric field, such as in the case of electro-suppressed helix in FLC (ESHFLC). To obtain the EO effect, in the case of DHFLC, p0 should be << d, and in the case of ESHFLC, p0 ≈ d.

[0007] Although the SSFLC effect is the most popular and widely studied, due to several fundamental problems, especially due to the poor alignment problem, SSFLC displays have not become commercially profitable products. In contrast, DHFLC with fewer alignment problems has the potential to combine the integrated advantages of the LC working medium for display applications with its fast response time, analog gray-scale ability, and excellent viewing angle of IPS. The performance of electro-optic properties, such as image quality, brightness, transmittance, contrast, switching time, the range of gray-scale variation, is correlated with the macroscopic parameters of FLC (spontaneous polarization, pitch, tilt angle, critical voltage for helix unwinding, etc.) in a complex way, which in turn depends on the molecular structure of the FLC constituent components.

[0008] High performance of DHFLC can only be achieved when all the macroscopic parameters are within the optimal range of their values. The importance of each of the macroscopic parameters and their allowed variations are given and defined below. For example, some studies have shown that the value of the pitch p0 is important for DHFLC performance, and its value is the result of a trade-off of several reasons:

[0009] (i) To meet the prerequisite of DHF existing in a cell gap with a thickness of 1.5 μm to 3 μm typically used, p0 should be much lower than 200 nm.

[0010] (ii) The spacing should be short enough to transfer the Bragg diffraction of the helical supramolecular structure to the ultraviolet region to ensure high contrast; when the p0 value is less than 120 nm, Bragg diffraction in the FLC phase cannot be observed at any angle.

[10]

[0011] (iii) On the other hand, due to the critical electric field (E) of the spiral unfolding c The pitch in DHFLC material should not be very tight, as it exceeds the available voltage of approximately 5V provided by thin-film transistors (TFTs).

[0012] However, parameter E c The value provided by the TFT and electric drive scheme should not be too small, because when the applied electric field E < E c The DHF effect was observed in LC, and within this range, transmittance depends almost linearly on E, thus achieving continuous and hysteresis-free grayscale. Therefore, an excessively tight p0 leads to a higher E. c This affects the grayscale range.

[0013] Other studies have shown that the optimal tilt angle (θ) for maximum transmittance under half-wave conditions should be 45°, i.e., birefringence Δn = λ / 2d [1,8,9]. However, θ can be reduced to 39° to 40° with acceptable low transmittance loss. Additionally, some studies have shown spontaneous polarization P... S For E c It has an impact on the transition time. It was also found that spontaneous polarization P... s The optimal range is 80 nC / cm 2 Up to 180 nC / cm 2 .

[0014] Although existing technologies and research have attempted to overcome this problem, the parameters provided in the research are far removed from the practical applications shown in our prior art analysis below.

[0015] EP0309774A2 describes an FLC display element based on the DHFLC effect. In the deformed spiral ferroelectric liquid crystal display element, the ratio of the liquid crystal layer thickness (d) to the FLC pitch is >5, the smectic tilt angle is 22.5° to 50°, and the product d(θ) 2 Δn(1 / λ) (phase factor, where Δn is the birefringence and λ is the wavelength of light) > 0.45 rad 2 The element may contain a mixture of pyrimidine derivatives and triphenyl dicarboxylate. The ratio of intercellular space to pitch, d / p0, is specified to be >10. The tilt angle used is 29°. Specific examples of FLC mixtures providing these parameters are as follows:

[0016]

[0017]

[0018] In EP0309774A2, the general formula for the chiral component is as follows, where R 1 and R 2 They are independent alkyl groups:

[0019]

[0020] EP0309774A2 specifies that the tilt angle (θ) ranges from 22.5° to 50°. However, no examples supporting this range of θ are provided in the following claims and patent specification. The maximum achievable value of θ for the chiral component in the prior art is 30°, see also the following prior art: Beresnev et al., Liquid Crystals, 1989, 5, 1171-1177.

[0021] Beresnev et al., Liquid Crystals, 1989, 5, 1171-1177, described a novel electro-optic effect in SmC* liquid crystals, termed the Deformed Helical Ferroelectric (DHF) effect. The DHF effect is based on the deformation of a helical structure caused by a weak electric field. In an unbiased device, the smectic layers are arranged in a bookshelf geometry with the helical axis parallel to the electrodes. Systems with very small pitch (<1 μm) and large tilt angles are particularly well-suited to this mode. The main characteristics of DHF LCDs are: (a) low driving field (1 V / μm represents maximum contrast); (b) grayscale approximately linear with the applied electric field; (c) easy alignment even for thick elements using standard wall alignment methods; and (d) a response time of 300 ps at room temperature. The parameters of the mixture found to have the DHF effect are as follows:

[0022] Ferroelectric liquid crystal for DHF-LCD mode

[0023]

[0024]

[0025] The chiral additive (chiral component) used is named LUCh-15, which is a derivative of terphenyl dicarboxylic acid. However, the exact chemical structures of both the chiral additive and the achiral SmC liquid crystal host are not disclosed. Based on Beresnev et al., Molecular Crystals and Liquid Crystals, 299:1, 525-539, it can be inferred that LUCh-15 is:

[0026]

[0027] The parameters reported by Beresnev et al., Liquid Crystals, 1989, 5, 1171-1177 (θ = 29° to 30°, pitch p0 = 0.3 μm to 0.4 μm, P) S (etc.) is far from sufficient for practical applications.

[0028] EP0339414A2 describes an optically active diester compound having general formula I, wherein A, B, C = unsubstituted 1,4-phenylene or halogen-, CN-, Me-, or MeO-substituted 1,4-phenylene, wherein one or two CH2 groups may be substituted with N; R* = optically active terpene alcohol after OH separation, or (CH2). m CHXR* or CH2) n CHX2R* free radicals.

[0029]

[0030] Claim 1 of prior art EP0339414A2 restricts variations of rings A, B, and C such that no more than one of them is pyrimidine-2,5-diyl or pyridin-2,5-diyl, or they are all 1,4-phenylene rings, wherein Y1 and Y2 are independently H or halogens, provided that at least one of Y1 and Y2 is different from hydrogen when both R' and R' are 2-alkyl. This prior art measured the spontaneous polarization of a mixture of 5% chiral component with a phenyl benzoate-type SmC host at 40°C. The spontaneous polarization was 0.51 nC / cm. 2 Up to 20 nC / cm 2 The melting point varies between these values. The bulk's melting point is much higher than room temperature, similar to the mixed CC used in monomer applications, which is unsuitable for practical use. No further data (p0, θ, conversion time) are described regarding the properties of these materials.

[0031] Fünfschilling et al., J. Appl. Phys. 66, 3877 (1989), described the findings on the electro-optic and display properties of liquid crystal devices based on the deformed helical ferroelectric (DHF) effect, which demonstrated TV switching rates and low driving voltages. The DHF effect is based on S*C ferroelectric liquid crystals with very short pitches, which form smectic bookshelf arrangements in suitable elements, where the helical axis is parallel to the display plane. The helical deformation caused by the application of an electric field is the cause of the electro-optic effect. If the pitch is shorter than the wavelength, the deformation leads to a change in the effective refractive index.

[0032] However, the spiral unwinding is one of the limitations of these devices. Studies have shown that standard component fabrication techniques and driving schemes (including active matrix addressing) can minimize spiral unwinding and produce highly reusable displays with short response times in the 10-μs region. A black-to-white contrast ratio of >12:1 has also been reported at driving voltages <2V and grayscale levels.

[0033] Fünfschilling et al., J. Appl. Phys. 66, 3877 (1989), and Beresnev et al., Liquid Crystals, 1989, 5, 1171-1177, differ in that they used FLC materials. In Fünfschilling et al., J. Appl. Phys. 66, 3877 (1989), experiments were conducted using the Hoffmann-LaRoche ferroelectric mixture FLC 5679. FLC 5679 exhibited the following properties:

[0034] Phase transition temperatures (°C): Cr-5, SmC*60, SmA 62–Iso,

[0035] Spontaneous polarization P S =100nC / cm 2 ,

[0036] The pitch p0 = 0.35 μm, and

[0037] Inclination angle θ = 38°

[0038] It is worth noting that the FLC in DHF elements exhibits a significantly fewer number of defects compared to the SSFLC effect. An advantage is that the tilt angle (θ) is high enough to provide 94% of the theoretical transmittance, allowing Ps = 100 nC / cm. 2 Spontaneous polarization. On the other hand, the temperature dependence θ(T) is not described, the SmC* range is also narrow, the pitch is not tight enough, and diffraction in the blue range and the 12:1 contrast defect alignment are reduced together.

[0039] Beresnev et al., Mat. Res. Soc. Symp. Proc., 1998, Vol. 488, 859-865, describe the development of an optically addressed spatial light modulator (OASLM) based on deformed helical ferroelectric liquid crystal (DHFLC) with a high tilt angle of approximately 40° and a pitch of less than 0.2 μm. The diffraction efficiency reaches approximately 20%. The photoinduced optical axis deviation of the DHFLC layer was measured in a sandwich structure consisting of a photoconductor and a liquid crystal. The photoelectric parameters of photoconductive amorphous silicon carbide α-SiC:H and photoconductive polymer films with and without light-blocking and reflective layers were measured. The application of the developed OASLM in a holographic image corrector was demonstrated.

[0040] The material parameters for DHFLC are as follows.

[0041]

[0042] Beresnev et al., Mat. Res. Soc. Symp. Proc., 1998, Vol. 488, 859-865, exhibited high tilt angles and spontaneous polarization. However, no composition of the material and Vc was reported; it was only known that the chiral component was a diester of triphenyl dicarboxylic acid alone or a mixture of diesters of triphenyl dicarboxylic acid. Furthermore, the spacing of the SmC* phase was insufficient to meet current requirements, the pitch of the three mixtures was close to the upper limit of acceptable values, and the drive voltage (30 V) was too high for current applications. No information regarding Vc was provided.

[0043] JP05017409A describes diester I (R1-R2=C) 4-20 Optically active groups (n = 0-2) and chiral smectic liquid crystal compositions containing them. The chiral compound itself or by mixing with a smectic C liquid crystal compound displays a chiral smectic phase and provides a liquid crystal display device with high-speed response.

[0044]

[0045] Electro-optic data for a 10 mol% mixture of CC with the following achiral host:

[0046]

[0047]

[0048]

[0049] The advantages of JP05017409A include its synthetic method, providing chiral compounds with terphenyl or tetraphenyl cores having different substituents at each terminal position, and exhibiting high spontaneous polarization P. S value.

[0050] However, a drawback of JP05017409A is that the described FLC materials are specified for SSFLC electro-optic effects. Therefore, their parameters do not meet the requirements for DHFLC in terms of pitch values. Consequently, the CH3 and CF3 groups with the same configuration (S or R) chiral centers provide opposite twists of the helix [see Mikhailenko et al., Mol. Liq. 281 (2019) 186-195]. If both groups are embedded in the same molecule, the resulting pitch for observing DHF will be too high. Biphenylpyrimidine is also not mentioned in examples of achiral hosts.

[0051] JP05213827A describes an optically active dihydroxytriphenyl dicarboxylate and a chiral smectic liquid crystal composition, wherein the chiral smectic liquid crystal composition contains ≥2 mol.% I(R) 1-2 =C 4-20 Optically active groups; n = 0-2). Chiral smectic C liquid crystal compositions containing I exhibit large spontaneous polarization and high-speed response, and can be used in display devices.

[0052]

[0053] JP05213827A describes advantages and disadvantages similar to those in JP05017409A, except that the chemical structure of the chiral component has been slightly altered.

[0054] EP546298A2 describes fatty acid esters (R1 = unsubstituted or C substituted with ≥1 halogen) by general formula I. 1-12 Alkyl or C 2-12 Alkenyl group, wherein the methylene group may be substituted with -O-; R2 = unsubstituted or C substituted with ≥1 halogen. 1-12 Alkyl or C 2-12 Alkenyl groups, wherein ≥1 methylene group may be substituted with -O- and / or -COO- or -OOC-; Z1 = single bond or -CH2CH2-; A1, A2 = independently selected from unsubstituted or substituted with ≥1 halogen 1,4-phenylene, pyridin-2,5-diyl or pyrimidine-2,5-diyl groups; A3 = unsubstituted or substituted with ≥1 halogen 1,4-phenylene, pyridin-2,5-diyl, pyrimidine-2,5-diyl or trans-1,4-cyclohexenyl groups; n = 0 or 1; the restriction is that ≥1 of A1, A2 and A3 is selected from pyridin-2,5-diyl and pyrimidine-2,5-diyl, and if n = 0, then R1 = 1-E-alkenyl group and R2 = alkyl, alkoxy or alkenyloxy group). Liquid crystal mixtures with ≥2 components (containing ≥1 ester) are also described, along with the use of these compounds in electro-optical applications (e.g., displays). EP546298A2 describes the optimization of an achiral host, modifying a common SmC host composed of a bicyclic phenylpyrimidine and a tricyclic compound with an aliphatic ester tail at the terminal position. This optimization allows for reduced conversion time due to decreased viscosity. The chiral component used in EP546298A2 is a diester of triphenyl dicarboxylic acid.

[0055] EP814368A2 describes an electro-optic material capable of altering its optical properties when an electric field is applied, wherein one or more laminar liquid crystals have a predetermined concentration of chiral molecules whose longitudinal axis is larger than that of the laminar liquid crystal forming molecules, such that the longitudinal axis of the chiral molecules is statistically tilted at a predetermined angle relative to the vertical direction of the liquid crystal layer when no electric field is applied.

[0056] The material claimed in EP814368A2 is designed for electrically driven tilt changes. The assumed molecular packing model based on EP814368A2 is given below. EP814368A2 describes that if the chiral molecule is longer than the host molecule, the chiral compound will adopt a certain pre-tilt in the LC mixture at the temperature where the SmA phase is present.

[0057]

[0058] However, the SmC* phase formed by these components is narrow to 42°C to 43°C, and the maximum tilt angle in the SmC* phase does not exceed 17°.

[0059] Beresnev et al., Molecular Crystals and Liquid Crystals, 299:1, 525-539, used the same materials described in EP814368A2 and also studied the effects.

[0060] Mikhailenko et al., J.Mol.Liq.281(2019)186-195, describe the design and research of high-performance ferroelectric liquid crystal (FLC) materials. High torsional capacity and large spontaneous polarization (P...) S >100nC / cm 2 The combination of these elements yields promising FLC hybrids: near-defect-free alignment in electro-optical devices, optical quality comparable to nematic liquid crystal-based devices, but with faster switching times. The most important parameter contributing to the material's remarkable performance is its ultrashort pitch down to 65 nm. The key components providing these advanced properties are a diester of a high-torsion triphenyl dicarboxylic acid and a chiral 1,1,1-trifluoroalkyl-2-ol (FOTDA-n, n = 4-8), with the achiral host being a mixture of two phenylpyrimidines or two biphenylpyrimidines.

[0061]

[0062] The maximum tilt angle reported by Mikhailenko et al., J.Mol.Liq.281(2019)186-195, is 37°, which is based on a low margin requirement for FLC materials. However, it shows a sufficiently tight pitch and acceptable P s The mixture of the conversion time and the optimal example exhibits an unsatisfactory phase transition of approximately 12°C to 18°C.

[0063] Kula et al., Liquid Crystals, 40:1, 83-90, describe a novel synthetic method developed and optimized for chiral terphenyl and tetraphenyl diesters, bis[(1S)-1-methylheptyl]1,1':4',1”'-terphenyl-4,4”'-dicarboxylic acid esters, and bis[(1S)-1-methylheptyl]1,1':4',1”:4”,1”'-tetraphenyl-4,4”'-dicarboxylic acid esters. The proposed method allows for the synthesis of a series of laterally substituted oligophenyl diesters in good yields. Numerous S,S and R,R isomers were synthesized, and their thermodynamic properties were measured. Most compounds exhibited good solubility in various liquid crystal host mixtures and moderate helical twisting forces, parameters of which have been determined for many nematic materials (dielectrically positive or negative). The high birefringence of the oligophenyl cores makes them suitable as candidates for chiral dopants for generating medium-to-high birefringence nematic materials with helical and blue phases.

[0064] Among these compounds, chiral tetraphenylene is described as:

[0065]

[0066] These compounds have two chiral groups on both sides of the molecule; however, their melting point (mp) is too high to provide the required solubility in liquid crystal substrates.

[0067] Bezborodov et al., Liquid Crystals, 40:10, 1383-1390, describe the synthesis and mesocrystalline properties of novel liquid crystal tetrphenyl and cyclohexylterphenyl derivatives—based on which ferroelectric liquid crystal (FLC) compositions are based. The FLC compositions containing the novel tetrphenyl derivatives are characterized by a wide temperature range of the SmC* phase, low operating voltage, and excellent orientation quality of the elements (thermal and mechanical stability "shock-free"). However, these materials are designed for use in electro-optic SSFLC modes requiring low-twist FLCs. Therefore, the molecules contain only one chiral group, which does not allow for submicron pitch values.

[0068] EP0347941A2 and EP0293763A2 describe the synthesis and properties of 2-(4-alkylbiphenyl)-5-alkylpyrimidine.

[0069] Gray et al., Perkin Transactions 2 (1989) 2041-2053, describe the synthesis and properties of laterally fluorinated dialkyl terphenyls. Summary of the Invention

[0070] In one aspect, the present invention provides a ferroelectric liquid crystal (FLC) material for a deformable helical FLC (DHFLC) electro-optic mode device, comprising at least two components and exhibiting optimal electro-optic characteristics, wherein at least one FLC component is a chiral compound of formula (I):

[0071]

[0072] in:

[0073] n is 0 or 1;

[0074] R 1 R 2 R 3 and R 4 Each of the following is independently 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by one or more substituents selected from the group consisting of halogens and methyl groups, provided that the ring R 1 and ring R 4 None of them are unsubstituted 1,4-phenylene;

[0075] A 1 and A 2 It does not exist independently, which means that the group W 1 or W 2 Directly connected to ring R 1 or ring R 4 Or choose the group consisting of -O-, -S- and esters; and

[0076] W 1 and W 2 Independently chiral alkyl C m H 2m+1 or chiral alkenyl C m H 2m , where m = 4-14, and optionally one or more of the hydrogens are independently substituted by F, Cl or cyano, and optionally one or more CH2 are independently substituted by CF2, O or -CO- groups (provided that the two O atoms are not connected together).

[0077] Reviewing the current state of technology in the field of DHFLC materials, we can conclude that, ideally, each DHFLC parameter: θ, p0, P S E cThese parameters should be controlled independently within the FLC composition to bring them as close to their optimum as possible. Obtaining optimized DHFLCs with overall performance improvement is challenging because the molecular structure and content of the DHFLC components simultaneously affect multiple parameters. Therefore, it is necessary to optimize each parameter to improve the electro-optic effect performance of DHFLCs. Furthermore, it is also necessary to provide a new set of compounds or combinations thereof in FLC materials that combine effective optimal parameters to address or improve the aforementioned issues. Detailed Implementation

[0078] definition

[0079] The following words and terms used in this document shall have the meanings indicated below:

[0080] As used herein, the term "alkyl group" includes, within its meaning, the general formula C n H 2n+1 It consists of monovalent straight-chain or branched saturated aliphatic groups, wherein the number of carbons (n) varies between 4 and 16.

[0081] The term “alkenyl group” in its meaning includes monovalent (“alkenyl”) and divalent (“alkenyl”) straight-chain or branched unsaturated aliphatic hydrocarbon groups having 4 to 16 carbon atoms.

[0082] The term "average length," when used to refer to a compound or part, refers to the total length of the longest atomic chain within that compound or part. When the term "average length" is used in combination with a combination of at least two compounds, it defines the average concentration of the "average length" for each compound.

[0083] When the term "average length" is used in conjunction with a segment, it can be estimated by the number of units and / or atoms (e.g., CH2, CF2, O, -C(O)-) in that segment. It should be understood that the number of units and / or atoms is used interchangeably with the total length mentioned above to roughly compare the "average length" of different segments or different liquid crystal molecules.

[0084] Therefore, if the molecule has two alkyl chains C n H 2n+1 and C m H 2m+1 The total length of the two alkyl chains can then be estimated as (n+m). When the material contains different compounds, the average total length can be calculated taking into account the concentration of each i-component, i.e., by the following formula:

[0085]

[0086] Where k is the number of compounds and c is the concentration (%) of each compound.

[0087] Therefore, as an example, the total "average lengths" of the achiral hosts BPP-2, BPP-4, and BPP-6 described herein are 12.1, 12.3, and 12.0, respectively, which is approximately 12. The total length of W and A in the chiral dopant given in Example 1 is 18.

[0088] Similarly, it should be understood that when “average length” is used in conjunction with parts or compounds containing ring structures, if all ring structures (aromatic and heteroaromatic) are hexavalent and have very similar dimensions, the “average length” can be estimated alternatively based on the number of ring structures.

[0089] The term "helical torsion force" or HTP is used to characterize the ability of a chiral compound to induce helical alignment in its mixture with nematic achiral liquid crystals or smectic C-type achiral liquid crystals. The HTP value is calculated by HTP = 1 / (p0·c) or as the tangent of the linear correlation between 1 / p0 and c, where p0 is the pitch induced at the concentration of chiral compound c.

[0090] Unless otherwise specified, the terms “contain” and “include” and their grammatical variations are intended to indicate an “open” or “inclusive” language that includes the stated element, but also allows for the inclusion of other unreferenced elements.

[0091] As used herein, the term “about” typically refers to + / -5% of a specified value, more typically + / -4% of a specified value, more typically + / -3% of a specified value, more typically + / -2% of a specified value, even more typically / -1% of a specified value, or even more typically + / -0.5% of a specified value.

[0092] Throughout this disclosure, certain embodiments may be disclosed in a range format. It should be understood that the range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosed range. Therefore, the description of the range should be considered as specifically disclosing all possible subranges and individual numerical values ​​within that range. For example, a description of a range such as 1 to 6 should be considered as specifically disclosing subranges such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., and individual numbers within that range, such as 1, 2, 3, 4, 5, and 6. This applies regardless of how wide the range is.

[0093] Certain embodiments may also be described broadly and generally herein. Each narrower group of species and subgenus falling within the general scope of this disclosure also constitutes part of this disclosure. This includes a general description of embodiments with accompanying conditions or negative limitations from which any subject matter is removed from the species, regardless of whether the removed material is specifically described herein.

[0094] Exemplary, non-limiting embodiments of FLC materials for DHFLC electro-optic mode devices will now be disclosed.

[0095] FLC materials contain at least two components and exhibit optimal electro-optic properties, wherein at least one FLC component is a chiral compound of formula (I):

[0096]

[0097] in:

[0098] n is 0 or 1;

[0099] R 1 R 2 R 3 and R 4 Each of the following is independently 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by one or more substituents selected from the group consisting of halogens and methyl groups, provided that the ring R 1 and ring R 4 None of them are unsubstituted 1,4-phenylene;

[0100] A 1 and A 2 It does not exist independently, which means that the group W 1 or W 2 Directly connected to ring R 1 or ring R 4 Alternatively, select the group consisting of -O-, -S-, and esters;

[0101] W 1 and W 2 Independently chiral alkyl C m H 2m+1 or chiral alkenyl C m H 2m , where m = 4-14, and optionally one or more of the hydrogens are independently substituted by F, Cl or cyano, and optionally one or more CH2 are independently substituted by CF2, O or -CO- groups (provided that the two O atoms are not connected together).

[0102] Advantageously, make ring R 1 and ring R 4 Neither of the unsubstituted 1,4-phenylene compounds can increase the tilt angle (θ) of liquid crystal compositions derived from chiral compounds of formula (I). This can increase light transmission through the liquid crystal elements in the liquid crystal composition and improve the contrast of the composition. This can also increase the torsional force of the chiral compounds of formula (I), thereby allowing their use in FLC materials at relatively low concentrations.

[0103] W 1 and W 2 It is independently substituted at one or more chiral centers by at least one part selected from the group consisting of F, Cl, trifluoromethyl, O and cyano.

[0104] Advantageously, FLC materials can have a temperature of at least 50 nC / cm. 2 The high spontaneous polarization value is due to the highly polar groups (F, CF3, O, etc.) at the chiral center of the chiral component.

[0105] As an example, R 1 R 2 R 3 and R 4 Each can be an 1,4-phenylene group, which may be optionally substituted with two or three substituents selected from the group consisting of halogen and methyl.

[0106] As an example, R 1 and R 4 It can be independently selected from the group consisting of pyrimidine-2,5-diyl, pyridine-2,5-diyl and 1,4-phenylene, wherein the 1,4-phenylene is substituted by at least one F atom.

[0107] As an example, W 1 and W 2 Choose independently from the following groups:

[0108]

[0109] in

[0110] * indicates a chiral carbon atom;

[0111] X is fluorine or chloro, cyano; and

[0112] p is an integer in the range of 2 to 10 (that is, p is 2, 3, 4, 5, 6, 7, 8, 9 or 10).

[0113] As an example, a chiral compound of formula (I) can have formula (Ia):

[0114]

[0115] in:

[0116] R 3 It is 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by one or more substituents selected from the group consisting of halogens and methyl groups, and

[0117] W1 and W 2 Independently chiral alkyl C m H 2m+1 or chiral alkenyl C m H 2m , where m = 4-14, and optionally one or more of the hydrogens are independently substituted by F, Cl or cyano, and optionally one or more CH2 are independently substituted by CF2, O or -CO- groups (provided that the two O atoms are not connected together).

[0118] As an example, a chiral compound of formula (I) can have formula (Ib):

[0119]

[0120] in:

[0121] R 3 It is 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by one or more substituents selected from the group consisting of halogens and methyl groups, and

[0122] W 1 and W 2 Independently chiral alkyl C m H 2m+1 or chiral alkenyl C m H 2m , where m = 4-14, and optionally one or more of the hydrogens are independently substituted by F, Cl or cyano, and optionally one or more CH2 are independently substituted by CF2, O or -CO- groups (provided that the two O atoms are not connected together).

[0123] As an example, a chiral compound of formula (I) can have formula (Ic):

[0124]

[0125] in:

[0126] R 3 It is 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by one or more substituents selected from the group consisting of halogens or methyl groups; and

[0127] W 1 and W 2 Independently chiral alkyl C m H 2m+1 or chiral alkenyl C m H2m , where m = 4-14, and optionally one or more of the hydrogens are independently substituted by F, Cl or cyano, and optionally one or more CH2 are independently substituted by CF2, O or -CO- groups (provided that the two O atoms are not connected together).

[0128] As an example, a chiral compound of formula (I) can have formula (Id):

[0129]

[0130] in:

[0131] R 3 It is 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by one or more substituents selected from the group consisting of halogens or methyl groups; and

[0132] W 1 and W 2 Independently chiral alkyl C m H 2m+1 or chiral alkenyl C m H 2m , where m = 4-14, and optionally one or more of the hydrogens are independently substituted by F, Cl or cyano, and optionally one or more CH2 are independently substituted by CF2, O or -CO- groups (provided that the two O atoms are not connected together).

[0133] As an example, a chiral compound of formula (I) can have formula (Ie):

[0134]

[0135] in:

[0136] R 3 It is 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by one or more substituents selected from the group consisting of halogens or methyl groups; and

[0137] W 1 and W 2 Independently chiral alkyl C m H 2m+1 or chiral alkenyl C m H 2m , where m = 4-14, and optionally one or more hydrogens are independently substituted by F, and optionally one or more CH2 are independently substituted by CF2, O or -CO- groups (provided that the two O atoms are not connected together).

[0138] As an example, a chiral compound of formula (I) can have formula (If):

[0139]

[0140] in:

[0141] R 3 It is 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by one or more substituents selected from the group consisting of halogens or methyl groups; and

[0142] W 1 and W 2 Independently chiral alkyl C m H 2m+1 or chiral alkenyl C m H 2m , where m = 4-14, and optionally one or more of the hydrogens are independently substituted by F, Cl or cyano, and optionally one or more CH2 are independently substituted by CF2, O or -CO- groups (provided that the two O atoms are not connected together).

[0143] The chiral compounds of formula (I) can be selected from the group consisting of:

[0144]

[0145]

[0146] FLC materials may also contain at least one chiral smectic C liquid crystal compound of formula (II):

[0147]

[0148] in:

[0149] R 5 R 6 R 7 and R 8 Independently, it is 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by at least one substituent selected from the group consisting of halogen and methyl;

[0150] k is 0 or 1;

[0151] A 3 and A 4 Independently absent or selected from the group consisting of -O-, -S-, and esters; and

[0152] W 3 and W 4 Independently alkyl C m H 2m+1 or alkenyl C m H 2m , where m = 4-12, and optionally one or more of the hydrogens are independently substituted by F, and further optionally one or more CH2 are independently substituted by CF2, O or -CO- groups (provided that the two O atoms are not connected together).

[0153] Advantageously, the liquid crystal composition can have a high upper limit and a low melting point of a smectic liquid crystal phase.

[0154] Furthermore advantageously, since the liquid crystal composition contains three or four aromatic rings, it can have a desired birefringence value, for example, in the range of about 0.14 to about 0.26.

[0155] As an example, the achiral smectic C liquid crystal compound of formula (II) can have formula (IIa):

[0156]

[0157] in:

[0158] R 11 and R 12 Independently, it is 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by at least one substituent selected from the group consisting of halogens or methyl groups.

[0159] W 3 and W 4 Independently alkyl C m H 2m+1 or alkenyl C m H 2m Where m = 4-12, and optionally one or more hydrogen atoms are independently substituted by F, and further optionally one or more CH2 atoms are independently substituted by CF2, O, or -CO- groups (provided that the two O atoms are not bonded together); and

[0160] A 4 The group consisting of -O-, -S- and esters does not exist or is selected.

[0161] Advantageously, when the achiral smectic C liquid crystal compound of formula (II) has a tricyclic aromatic core, it can provide a high upper limit for the smectic phase, reaching at least about 100°C. More advantageously, a combination of at least three compounds of formula (II) can have a melting point of about 14°C to 20°C, and when combined with another chiral compound of formula I or a bicyclic achiral smectic material of formula II (such as 2-cyclophenylpyrimidine or phenylpyridine), the melting point can be easily further reduced to 0°C.

[0162] As an example, the achiral smectic C liquid crystal compound of formula (II) is selected from the group consisting of:

[0163]

[0164] FLC materials may contain more than one chiral smectic C liquid crystal compound of formula (II), therefore, in one example, the liquid crystal composition may contain:

[0165]

[0166] In another example, FLC material may include:

[0167]

[0168] In another example, FLC material may include:

[0169]

[0170] In another example, FLC material may include:

[0171]

[0172] In another example, FLC material may include:

[0173]

[0174] When an FLC material contains more than one achiral smectic C liquid crystal compound of formula (II), the more than one achiral smectic C liquid crystal compound of formula (II) can provide a suitable molar ratio combination of melting points for the FLC material. As an example, the more than one achiral smectic C liquid crystal compound of formula (II) can be configured with an approximately eutectic composition.

[0175] In the liquid crystal composition, R 1 R 2 R 3 and R 4 The total number of rings in the loop can be equal to R. 5 R 6 R 7 and R 8The total number of rings in the ring.

[0176] As an example, W 1 and W 2 The average length can be greater than W 3 and W 4 The average length.

[0177] Favorably, when W 1 and W 2 The average length is greater than W as described above. 3 and W 4 When the average length is 50, the liquid crystal composition can have a high helical twisting force of up to about 50.

[0178] As an example, W 1 and W 2 The average length can be equal to W 3 and W 4 The average length is W 3 and W 4 Its average length is at most twice as large.

[0179] Advantageously, setting an upper limit of approximately twice can prevent an undesirable reduction in the tilt angle of the liquid crystal composition.

[0180] The molar ratio of the chiral compound of formula (I) and the non-chiral smectic C liquid crystal compound of formula (II) can be in the range of about 10:90 to about 40:60, preferably about 10:90 to about 30:70, and more preferably about 20:80 to about 30:70.

[0181] Advantageously, when the chiral compound of formula (I) has the molar ratio as described above, the FLC material can have a low viscosity.

[0182] FLC materials may have a smectic C* phase ranging from at least about 10 °C to about 85 °C or more.

[0183] FLC materials can have an inclination angle in the range of about 35 degrees to about 47 degrees, preferably about 40 degrees to about 45 degrees.

[0184] FLC materials can exhibit high spontaneous polarization. As an example, when the concentration of the chiral compound in formula (I) is less than 20 mol% based on the total molar percentage of the FLC material, the FLC material can exhibit a polarization greater than 50 nC / cm² at standard ambient temperature (e.g., 25 °C) and pressure (e.g., 1 atm). 2 Or preferably greater than 100 nC / cm 2 Spontaneous polarization.

[0185] Liquid crystal compositions can have short pitches. As an example, when the concentration of the chiral compound of formula (I) is less than 20 mol% based on the total moles of the FLC material, the FLC material can have a pitch of less than 250 nm or preferably less than 120 nm under standard environmental conditions (temperature 25°C) and pressure (1 atm). Attached Figure Description

[0186] The accompanying drawings illustrate the disclosed embodiments and are used to explain the principles of the disclosed embodiments. However, it should be understood that the drawings are for illustrative purposes only and should not be construed as limiting the invention.

[0187] Figure 1 The temperature dependence of the tilt angle of the FLC-4-1 mixture is shown. The vertical dashed line represents the temperature at which the phase transition SmC*→SmA occurs in the absence of an external electric field.

[0188] Figure 2 The temperature dependence of spontaneous polarization of the mixture FLC-4-1 is shown. The vertical dashed line represents the temperature at which the phase transition SmC*→SmA occurs in the absence of an external electric field.

[0189] Figure 3 The temperature dependence of the pitch of the FLC-4-1 mixture is shown. The thick vertical line represents the temperature at which the phase transition SmC*→SmA occurs in the absence of an external electric field.

[0190] Figure 4 The response time τ of the FLC-4-1 at 90 Hz was shown at 25 °C and a component gap of 1.6 μm. ON Dependence.

[0191] Figure 5 The following data are shown: (a) the temperature dependence of the tilt angle of the FLC-4-7 mixture, where the vertical dashed line represents the temperature of the phase transition SmC*→SmA in the absence of an external electric field; (b) the temperature dependence of the spontaneous polarization of the FLC-4-7 mixture, where the vertical dashed line represents the temperature of the phase transition SmC*→SmA in the absence of an external electric field; and (c) the temperature dependence of the pitch (p0) of the FLC-4-7 mixture, where the vertical dashed line represents the temperature of the phase transition SmC*→SmA in the absence of an external electric field.

[0192] Figure 6 The response time τ of the FLC-4-7 mixture at 90 Hz was shown at 25 °C and a component gap of 1.6 μm. ON Dependence.

[0193] Figure 7 The temperature dependence of the tilt angle of the mixture FLC-6-1 is shown. The vertical dashed line represents the temperature at which the phase transition SmC*→SmA occurs in the absence of an external electric field.

[0194] Figure 8 The response time τ of the FLC-6-1 mixture at 90 Hz was shown at 25 °C and a component gap of 1.6 μm. ON Dependence.

[0195] Example

[0196] Overview

[0197] Non-limiting examples and comparative examples of the invention will be described in further detail with reference to specific embodiments, which should not be construed as limiting the scope of the invention in any way.

[0198] Unless otherwise specified, all chemicals are available from Merck, Meryer, Dieckmann HK, Fluorochem, or TCI and should be used upon receipt. Biphenylpyrimidine was supplied by TitanSci, China. Silica gel used for rapid chromatography is silica gel 60 (0.040 mm to 0.060 mm). Thin-layer chromatography (TLC) was performed on a Merck UV254 TLC plate using a suitable solvent as the eluent.

[0199] The following abbreviations for common chemicals were used:

[0200]

[0201] As described in V. Mikhailenko, D. Yedamenko, G. Vlasenko, A. Krivoshey, V. Vashchenko / / Tetrahedron Lett.-2015.-Vol.56,Is.43.-P.5956-5959, the synthesis of chiral 1-trifluoromethylalkanols with ee > 97% was carried out.

[0202] The chiral component with an unsubstituted central terphenyl ring (S-FODTA-n) used as a comparative compound, as described by Mikhailenko et al., J.Mol.Liq.281(2019)186-195, is synthesized.

[0203]

[0204] Bicyclic phenylpyrimidines were synthesized as described in EP0347941A2 (priority date 1988-06-24) and EP 0293763A2 (1988 / 12 / 07).

[0205] The synthesis of difluoroterphenyls is described in GWGray, M. Hird, D. Lacey, KJ Toyne, Journal of the Chemical Society, Perkin Transactions 2 (1989) 2041-2053.

[0206] Solution degassing was carried out by three consecutive cycles of pumping to ~100 mbar and filling with N2.

[0207] A mixture of compounds is prepared by thoroughly stirring an appropriate amount of the components at a temperature of 110°C to 120°C under a nitrogen atmosphere using a vibrator or magnetic stirrer for at least 10 minutes.

[0208] Phase transitions in LC mixtures were determined using differential scanning calorimetry on a Thermo Scientific DSC-25 instrument. LC phase partitioning was performed using polarized light microscopy on an Olympus BX-60 microscope equipped with a custom-designed hot stage.

[0209] As described in the prior art by Mikhailenko et al., J.Mol.Liq.281(2019)186-19, pitch is measured by selective reflection of light at normal and oblique incidence without an external voltage (p0). Elements of 15-25 μm in diameter are used, with the inner side coated with chromene as the vertically aligned material.

[0210] The FLC properties of the mixture were measured in an ITO-coated glass bath with a thickness ranging from 1.6 μm to 1.7 μm; the inner side of the bath was coated with a 30 nm unidirectional rubble-coated nylon-6 layer. The bath was mounted on a custom-made hot plate, providing temperature control of ±0.1 °C.

[0211] Spontaneous polarization (P) was measured by the reversing current passing through a cascaded 560 kOhm resistor. s The toggle current through the resistor is measured using an oscilloscope.

[0212] The tilt angle is measured by rotating the slot when a square wave of 10V / µm (Vpp) is applied to the slot. For both positive and negative polarities of the signal, the tilt angle is half the rotation angle when the output strength drops to zero.

[0213] Response time is the time required to change the optical transmittance from 10% to 90%.

[0214] When the response time reaches its maximum value, the critical voltage for spiral unwinding is determined as the critical voltage.

[0215] Examples 1-16 disclose methods for synthesizing compounds used as chiral components according to the claims.

[0216] Example 1

[0217] The synthesis of 2,2”-difluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid bis-(S-1-trifluoromethylheptyl) ester (1b) was carried out in two steps according to the following scheme:

[0218]

[0219] S-1-(trifluoromethyl)heptyl-2-fluoro-4-bromobenzoate (1a)

[0220] A solution of 3.27 g (15.8 mmol) DCC in 20 mL of dry DCM was added dropwise to a mixture of 2.89 g (13.2 mmol) 2-fluoro-4-bromobenzoic acid, 2.28 g (12.4 mmol) S-1-(trifluoromethyl)-heptanol, and 5 mg DMAP in 30 mL of DCM under stirring and cooling (ice water). The mixture was then stirred until the reaction was complete, and the reaction was monitored by TLC. The mixture was then filtered through a short-stoppered silica gel filter. The silica gel was washed separately with 150 mL of DCM. The combined solution in DCM was evaporated to dryness to give product 1a, 5.2 g of oil, which was cured during storage and used in the next step without further purification. 2,2”-Difluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid bis-(S-1-trifluoromethylheptyl) ester (1b)

[0221] A mixture of 2.22 g (5.8 mmol) 1a, 0.40 g (2.4 mmol) 1,4-phenylenediboronic acid, 0.30 g SDS, 0.171 g PdCl2dppf, 5 mL 1-butanol, 10 mL water, and 30 mL toluene was degassed, then heated to reflux and a degassed solution of 2.90 g (34.8 mmol) NaHCO3 in 20 mL water was added dropwise. The reaction mixture was refluxed for another 2 hours, then cooled to ambient temperature, and the organic layer was separated. The remaining aqueous layer was then extracted three times with toluene. The combined organic layers were washed with water, dried with Na2SO4, and purified by rapid toluene chromatography on a short silica gel stopper. The resulting toluene fraction containing the desired product was evaporated to dryness. The residue was purified by silica gel column chromatography [50 × 2 cm, eluent TolH:hexane (1:1 w / w)] to give 1.00 g (62%) of product (1b) as a colorless oil.

[0222] Example 2

[0223] Synthesis of 2,2”-difluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid bis-(S-1-trifluoromethyloctyl) ester

[0224]

[0225] Following the scheme described in Example 1, 2,2”-difluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid bis(S-1-trifluoromethyloctyl) ester was synthesized using the starting materials 2.19 g (10 mmol) of 2-fluoro-4-bromobenzoic acid, 1.70 g (10 mmol) of S-1-(trifluoromethyl)octanol, and 0.59 g (3.50 mmol) of 1,4-phenylenediamine to obtain 1 g (40%) of the desired product, which was a colorless oil.

[0226] Example 3

[0227] Synthesis of 2,2”-difluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid bis-(S-1-trifluoromethylhexyl) ester

[0228]

[0229] Following the scheme described in Example 1, 2,2”-difluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid bis-(S-1-trifluoromethylhexyl) ester was synthesized using the starting materials 2.19 g (10 mmol) of 2-fluoro-4-bromobenzoic acid, 1.70 g (10 mmol) of S-1-(trifluoromethyl)hexanol, and 0.60 g (3.62 mmol) of 1,4-phenylenediamine to obtain 1.10 g (46%) of the desired product as a colorless oil.

[0230] Example 4

[0231] Synthesis of 3,3”-difluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid bis-(S-1-trifluoromethylheptyl) ester

[0232]

[0233] Following the scheme described in Example 1, 3,3”-difluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid bis(S-1-(trifluoromethyl)heptyl) ester was synthesized using the starting materials 1.78 g (8.1 mmol) of 3-fluoro-4-bromobenzoic acid, 1.51 g (8.2 mmol) of S-1-(trifluoromethyl)heptyl alcohol, and 0.60 g (3.62 mmol) of 1,4-phenylenediamine to obtain 1.21 g (49%) of the desired product as a colorless oil.

[0234] Example 5

[0235] Synthesis of 2,3,2”,3”-tetrafluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid bis-(S-1-trifluoromethylheptyl) ester

[0236]

[0237] Following the scheme described in Example 1, 2,3,2”,3”-tetrafluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid bis-(S-1-trifluoromethylheptyl) ester was synthesized using the starting materials 1.45 g (6.1 mmol) of 2,3-difluoro-4-bromobenzoic acid, 1.130 g (6.1 mmol) of S-1-(trifluoromethyl)heptanol, and 0.50 g (3.02 mmol) of 1,4-phenylenediamine, yielding 1.20 g (55%) of the desired product with a melting point of 63 °C.

[0238] Example 6

[0239] Synthesis of bis(S-1-trifluoromethylheptyl) ester of 6,6'-(1,4-phenylene)dipyridinecarboxylate

[0240]

[0241] Following the scheme described in Example 1, bis((S)-1-trifluoromethylheptyl) ester of 6,6'-(1,4-phenylene)pyridinecarboxylic acid was synthesized using 2.024 g (10 mmol) of starting materials, 1.760 g (9.54 mmol) of S-1-(trifluoromethyl)heptanol, and 0.624 g (3.76 mmol) of 1,4-phenylene diboronic acid, yielding 1.00 g (41%) of the desired product with a melting point of 57 °C.

[0242] Example 7

[0243] Synthesis of bis(S-1-trifluoromethylheptyl) ester of 5,5'-(1,4-phenylene)dipyridinecarboxylate

[0244]

[0245] Following the scheme described in Example 1, bis((S)-1-trifluoromethylheptyl) ester of 5,5'-(1,4-phenylene)dipyridinecarboxylic acid was synthesized using 1.94 g (9.6 mmol) of 5-bromopyridinecarboxylic acid, 1.79 g (9.7 mmol) of S-1-(trifluoromethyl)heptanol, and 0.58 g (3.5 mmol) of 1,4-phenylene diboronic acid, yielding 0.85 g (37%) of the desired product with a melting point of 49 °C.

[0246] Example 8

[0247] Synthesis of 2,2'-(1,4-phenylene)bis(pyrimidin-5-carboxylic acid)bis(S-1-trifluoromethylheptyl) ester

[0248]

[0249] Following the scheme described in Example 1, 2,2'-(1,4-phenylene)bis(pyrimidin-5-carboxylic acid)bis(S-1-trifluoromethylheptyl) ester was synthesized using the starting materials 2.03 g (10 mmol) of 2-bromopyrimidin-5-carboxylic acid, 1.86 g (10.1 mmol) of S-1-(trifluoromethyl)heptanol, and 0.58 g (3.5 mmol) of 1,4-phenylene diboronic acid, yielding 1.02 g (45%) of the desired product with a melting point of 62 °C.

[0250] Example 9

[0251] Synthesis of 5,5'-(1,4-phenylene)bis(pyrimidin-2-carboxylic acid)bis-(S-1-trifluoromethylheptyl) ester

[0252]

[0253] Following the scheme described in Example 1, 5,5'-(1,4-phenylene)-bis(pyrimidin-2-carboxylic acid)bis((S)-1-(trifluoromethyl)heptanol) ester was synthesized using the starting materials 1.55 g (7.6 mmol) of 5-bromopyrimidin-2-carboxylic acid, 1.50 g (8.1 mmol) of S-1-(trifluoromethyl)heptanol, and 0.43 g (2.6 mmol) of 1,4-phenylene diboronic acid, yielding 0.85 g (50%) of the desired product with a melting point of 70 °C.

[0254] Example 10

[0255] Synthesis of 3,3”-difluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid bis((S)-octane-2-yl) ester

[0256]

[0257] Following the scheme described in Example 1, 3,3”-difluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid bis((S)-octane-2-yl) ester was synthesized using the starting materials 2.19 g (10 mmol) of 2-fluoro-4-bromobenzoic acid, 1.30 g (10 mmol) of S-1-methylheptanol, and 0.50 g (3 mmol) of 1,4-phenylenediamine, yielding 0.902 g (52%) of the desired product as a colorless oil.

[0258] Example 11

[0259] The synthesis of [1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid 4-((S)-1-ethoxy-1-oxopropane-2-yl)4”-((S)-1,1,1-trifluorooctane-2-yl) ester (11c) was carried out in three steps according to the following scheme:

[0260]

[0261] Synthesis of 4'-bromo-[1,1'-biphenyl]-4-carboxylic acid (S)-1-ethoxy-1-oxopropane-2-yl ester (11a)

[0262] A solution of DCC (3.2 g, 15.6 mmol) in 60 ml of dry DCM was added dropwise to a suspension of 4'-bromo-[1,1'-biphenyl]-4-carboxylic acid (3.6 g, 13 mmol), (S)-(-)-ethyl lactate (1.69 g, 14.3 mmol), and DMAP (1.9 g, 15.6 mmol) in 100 ml of dry DCM under stirring at 5 °C. The mixture was heated to ambient temperature and stirred for 18 hours. The mixture was then filtered through a diatomaceous earth sieve, and the filtrate was washed successively with dilute HCl, saturated sodium carbonate, and brine. The organic layer was then evaporated to dryness. The residue after evaporation was purified by silica gel rapid chromatography with a mixture of toluene and hexane (1 / 1) to give 4.6 g of 11a (94%) as a yellow oil.

[0263] Synthesis of 4'-(4,4,5,5-tetramethyl-1,3,2-dioxaboron-2-yl)-[1,1'-biphenyl]-4-carboxylic acid (S)-1-ethoxy-1-oxopropane-2-yl ester (11b)

[0264] A degassed mixture of 2 g (5.32 mmol) of 11a, 2 g (7.78 mmol) of bis-(pinacol)-diboron, 2.34 g of anhydrous potassium acetate, and 0.08 g of PdCl2 dppf (0.106 mmol) in 25 mL of dioxane was stirred at 85 °C for 16 hours. After cooling to ambient temperature, the product was extracted with ethyl acetate (3 × 20 mL). The combined organic layers were then washed with water and evaporated to dryness. The residue was purified by silica gel rapid chromatography with toluene:hexane (1:1 v / v) as eluent. The fraction containing the desired product was evaporated to dryness to give 2.1 g of 11b (93%) as a yellow oil.

[0265] Synthesis of [1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid 4-((S)-1-ethoxy-1-oxopropane-2-yl)4”-((S)-1,1,1-trifluorooctane-2-yl) ester (11c)

[0266] A mixture of 1 g (2.36 mmol) 11b, 0.739 g (2.36 mmol) 1a (see Example 1), 0.052 g (0.071 mmol) PdCl2dppf, and SDS (0.3 mg) in a mixture of toluene (30 ml), n-butanol (5 ml), and H2O (20 ml) was degassed under vacuum and washed five times with nitrogen, then heated to reflux with stirring. A solution of Na2CO3·H2O (0.880 g, 6.08 mmol) in 10 ml of water was added to the refluxed mixture, which was then degassed by bubbling with nitrogen. The resulting mixture was stirred under reflux for 3 hours and cooled. The organic layer was separated, and the aqueous layer was extracted with toluene (3 × 20 ml). The organic extract was collected, washed with water, and evaporated to dryness. The residue was purified by silica gel rapid chromatography with a mixture of toluene and hexane (1 / 1), and recrystallized sequentially from hexane and acetonitrile. Yield: 0.36 g (28%).

[0267] Example 12

[0268] Synthesis of 3-fluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid 4”-((S)-1-ethoxy-1-oxopropane-2-yl)4-((S)-1,1,1-trifluorooctane-2-yl) ester

[0269]

[0270] Following the scheme described in Example 11, 3-fluoro-[1,1':4',1”-terphenyl]-4,4”-dicarboxylic acid 4”-((S)-1-ethoxy-1-oxopropane-2-yl)4-((S)-1,1,1-trifluorooctane-2-yl) ester was synthesized using the starting material (S)-1,1,1-trifluorooctane-2-yl) ester; the yield was 0.32 g (23%) of the desired product, which was a colorless solid.

[0271] Example 13

[0272] The synthesis of [2,2'-bidinaphthalene]-6,6'-dicarboxylic acid bis((S)-1,1,1-trifluorooctane-2-yl) ester (13c) was carried out in three steps according to the following scheme:

[0273]

[0274] Synthesis of 6-bromo-2-naphthoic acid (S)-1,1,1-trifluorooctane-2-yl ester (13a)

[0275] A solution of DCC (2.95 g, 14.3 mmol) in dry dichloromethane (40 ml) was added dropwise to a suspension of 6-bromo-2-naphthoic acid (2.98 g, 11.9 mmol), (S)-1,1,1-trifluorooctane-2-ol (2.29 g, 12.4 mmol), and DMAP (160 mg, 1.3 mmol) in dry dichloromethane (90 ml) under stirring at 0 °C–5 °C. The mixture was heated to room temperature overnight under stirring. It was then filtered through a diatomaceous earth sieve and evaporated to dryness. The residue after evaporation was purified by rapid chromatography with hot heptane to give 13a as a clear solid. Yield: 1.5 g (32%).

[0276] Synthesis of 1,1,1-trifluorooctane-2-yl ester (13b) of 6-(4,4,5,5-tetramethyl-1,3,2-dioxaborane-2-yl)-2-naphthoic acid

[0277] A mixture of 0.70 g (1.68 mmol) of 6-bromo-2-naphthoic acid (S)-1,1,1-trifluorooctane-2-yl ester, 0.64 g (2.52 mmol) of bis(pinacol)diboron, 0.495 g of anhydrous KOAc, and 0.025 g of PdCl2dppf (0.0336 mmol) in 15 mL of dioxane was degassed and packed with N2, then heated at 85 °C for 16 h. After cooling to ambient temperature, the product was extracted with ethyl acetate (3 x 20 mL). The combined organic layers were then washed with water and evaporated to dryness. The residue was purified by silica gel rapid chromatography with toluene:hexane (1:1 v / v) as eluent. The fraction containing the desired product was evaporated to dryness to give 0.5 g of 13b (67%) as a colorless oil.

[0278] Synthesis of [2,2'-Bidinaphthalene]-6,6'-dicarboxylic acid bis((S)-1,1,1-trifluorooctane-2-yl) ester (13c)

[0279] A degassed solution of 13b (0.5 g, 1.68 mmol), 6-bromo-2-naphthoic acid (S)-1,1,1-trifluorooctane-2-yl ester (0.7 g, 1.68 mmol), PdCl2dppf (0.037 g, 0.05 mmol), and SDS (0.2 mg) in a mixture of toluene (20 mL), n-butanol (5 mL), and H2O (10 mL) was heated to reflux with stirring. Then, a degassed solution of Na2CO3·H2O (0.83 g, 6.72 mmol) in 10 mL of water was added. The resulting mixture was refluxed for 3 hours and cooled to ambient temperature. The organic layer was separated, and the aqueous layer was extracted with toluene (3 × 20 mL). The organic extract was collected, washed with water, and evaporated to dryness. The residue was purified by silica gel rapid chromatography with a mixture of toluene and hexane (1 / 1). The yield was 0.48 g (46%) as a colorless oil.

[0280] Example 14

[0281] The synthesis of 6,6'-(1,4-phenylene)bis(2-naphthoic acid)bis((S)-1,1,1-trifluorooctane-2-yl) ester (14) was carried out in two steps according to the following scheme:

[0282]

[0283] A solution of 0.7 g (1.68 mmol) of compound 13a (see Example 13), 1,4-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborpentane-2-yl)benzene (0.253 g, 0.76 mmol), PdCl2dppf (0.035 g, 0.046 mmol), and SDS (0.2 mg) in a mixture of toluene (20 ml), n-butanol (5 ml), and H2O (10 ml) was degassed under vacuum and washed five times with nitrogen, then heated to reflux with stirring. A degassed solution of Na2CO3·H2O (0.754 g, 6.08 mmol) in 10 ml of water was then added. The resulting mixture was stirred under reflux for 3 hours and cooled. The organic layer was separated, and the aqueous layer was extracted with toluene (3 × 20 ml). The organic extract was collected, washed with water, and evaporated to dryness. The residue was purified by rapid silica gel chromatography with toluene:hexane (1 / 1 w / w) as eluent and recrystallized from acetonitrile. Yield: 0.26 g (46%), melting point: 135 °C.

[0284] Example 15

[0285]

[0286] A solution of 0.8 g (3.3 mmol) of 4,4'-biphenyl dicarboxylic acid (15a) and 3 drops of DMF in a mixture of 10 mL SOCl2 and 20 mL toluene was refluxed for 6 hours and then evaporated to dryness. The residue after evaporation was dissolved in 20 mL of dry dioxane, and 1.24 g of (S)-1-(trifluoromethyl)heptanol was added. The solution was heated to 50 °C and 3.5 mL of pyridine was added dropwise with stirring. The mixture was then refluxed for 4 hours, evaporated to dryness, and purified by silica gel rapid chromatography with a mixture of hexane-toluene 1:1 v / v. The yield of 15b was 1.18 g (62%) as a colorless oil.

[0287] Example 16

[0288] The synthesis of 4,4”-bis((((S)-1-(trifluoromethyl)heptyl)oxy)methyl)-1,1':4',1”-terphenyl (16b) was carried out according to the following scheme:

[0289]

[0290] Synthesis of (S)-1-bromo-4-(((1,1,1-trifluorooctane-2-yl)oxy)methyl)benzene (16a). At 25 °C under a N2 atmosphere, 1.17 g (6.37 mmol) of (S)-1-(trifluoromethyl)heptanol was added to a mixture of 0.382 g (9.56 mmol) NaH (60% oil suspension) in 15 mL of dry DMF and stirred for 4 h. Then, a solution of 1.75 g (7.01 mmol) of 1-bromo-4-(bromomethyl)benzene in 9 mL of dry DMF was added and stirred for 28 h. The mixture was then diluted with cold 3% AcOH aqueous solution, extracted with DCM, washed with water, and dried over Na2SO4. The drying agent was filtered off, and the DCM solution was evaporated to dryness. The crude product was purified by silica gel / hexane rapid chromatography to give 2.106 g (94%) of 16a as a colorless oil, which was used in the next step without further purification.

[0291] The synthesis of 4,4”-bis((((S)-1-(trifluoromethyl)heptyl)oxy)methyl)-1,1':4',1”-terphenyl (16b) was carried out according to the scheme described in stage b of Example 1.

[0292] Amount: 2.0 g (5.7 mmol) (S)-1-bromo-4-(((1,1,1-trifluorooctane-2-yl)oxy)methyl)benzene (16a); 0.425 g (2.57 mmol) 1,4-phenylenediboronic acid; the yield of the desired product 16b was 0.516 g (32%), as a colorless solid.

[0293] Examples 17-22 disclose the composition of LC mixtures used as non-chiral bodies.

[0294] Example 17

[0295] Table 1. Main Mixture BPP-2

[0296]

[0297] The mixture BPP-2 exhibits the following phase transition:

[0298]

[0299] Example 18

[0300] Table 2. Main mixture BPP-3

[0301]

[0302]

[0303] The mixture BPP-3 exhibited the following phase transition:

[0304]

[0305] Example 19

[0306] Table 3. Main mixture BPP-4

[0307]

[0308] The mixture BPP-4 exhibited the following phase transition:

[0309]

[0310] Example 20

[0311] Table 4. Main mixture BPP-6

[0312]

[0313]

[0314] The mixture BPP-6 exhibited the following phase transition:

[0315]

[0316] Example 21

[0317] Table 5. Main mixtures of three laterally fluorinated dialkyl terphenyls (DFTs)

[0318]

[0319] The mixture DFT showed the following phase transition:

[0320]

[0321] Example 22

[0322] Table 6. Main Mixture PP-7

[0323]

[0324] The mixture PP-7 exhibited the following phase transition:

[0325]

[0326] Continuing, multicomponent mixtures of biphenylpyrimidine (BPP-4 and BPP-6) and DFT mixtures exhibit a sufficiently wide desired SmC phase range from about 13°C to 20°C to 91°C to 103°C, thus making them suitable as achiral hosts. BPP-2 and BPP-3, with even higher melting points of 28°C and 36°C respectively, make them suitable media for comparisons of chiral component expression only.

[0327] Examples 23-55 disclose the composition and properties of FLC mixtures of chiral components (type I compounds) and achiral hosts.

[0328] Example 4

[0329] Table 1. Composition of FLC-3-1 mixture

[0330]

[0331] Table 2. Properties of FLC-3-1 mixtures (at 25°C)

[0332]

[0333] The parameters displayed by FLC-3-1 are close to their optimal values.

[0334] Example 5

[0335] Table 3. Composition of FLC-3-2 mixture

[0336]

[0337] Table 4. Properties of FLC-3-2 mixtures (at 25°C)

[0338]

[0339] The mixture FLC-3-2 shows the minimum concentration of the chiral component.

[0340] Example 6

[0341] Table 11. Composition of FLC-3-3 mixture

[0342]

[0343] Table 5. Properties of FLC-3-3 mixtures (at 25°C)

[0344]

[0345] The effect of variations in the linker type between the central core and the terminal chiral groups. The mixture shows poor alignment in the FLC element.

[0346] Example 7

[0347] Table 6. Composition of FLC-3-4 mixture

[0348]

[0349] Table 7. Properties of FLC-3-4 mixtures (at 25°C)

[0350]

[0351] The mixture demonstrates the effect of variations in linker type between the central core and terminal chiral groups. The mixture also shows poor alignment within the FLC element.

[0352] Example 8

[0353] Table 8. Composition of FLC-3-5 mixture

[0354]

[0355] Table 9. Properties of FLC-3-5 mixtures (at 25°C)

[0356]

[0357] This shows a comparative example of results for known chiral components.

[0358] Example 9

[0359] Table 10. Composition of FLC-4-1 mixture

[0360]

[0361] Table 18. Properties of FLC-4-1 mixtures (at 25°C)

[0362]

[0363] The parameters displayed by FLC-4-1 are close to their optimal values.

[0364] Example 10

[0365] FLC-4-2 composition

[0366] Table 11. Composition of FLC-4-2 mixture

[0367]

[0368] Table 12. Properties of FLC-4-2 mixtures (at 25°C)

[0369]

[0370] FLC-4-2 is a mixture used to determine the minimum concentration of chiral components with an acceptable property set.

[0371] Example 30

[0372] Table 21. Composition of FLC-4-3 mixture

[0373]

[0374] Table 13. Properties of FLC-4-3 mixtures (at 25°C)

[0375]

[0376]

[0377] The examples show the effect of terminal alkyl chain length; see Example 28.

[0378] Example 31

[0379] Table 14. Composition of FLC-4-4 mixture

[0380]

[0381] Table 15. Properties of FLC-4-4 mixtures (at 25°C)

[0382]

[0383] The examples show the effect of terminal alkyl chain length; see Example 28.

[0384] Example 32

[0385] Table 16. Composition of FLC-4-5 mixture

[0386]

[0387]

[0388] Table 17. Properties of FLC-4-5 mixtures (at 25°C)

[0389]

[0390] The examples demonstrate the effect of moving the polar groups in the central nucleus of a chiral component molecule toward its center; see Example 28.

[0391] Example 11

[0392] Table 18. Composition of FLC-4-6 mixture

[0393]

[0394] Table 19. Properties of FLC-4-6 mixtures (at 25°C)

[0395]

[0396]

[0397] The examples illustrate the effect of the movement of polar groups in the central nucleus of a chiral component molecule toward its center on the tilt angle, see Example 28.

[0398] Example 12

[0399] Table 20. Composition of FLC-4-7 mixture

[0400]

[0401] Table 21. Properties of FLC-4-7 mixtures (at 25°C)

[0402]

[0403] Example 13

[0404] Table 22. Composition of FLC-4-8 mixture

[0405]

[0406]

[0407] Table 23. Properties of FLC-4-8 mixtures (at 25°C)

[0408]

[0409] Example 14

[0410] Table 24. Composition of FLC-4-9 mixture

[0411]

[0412] Table 25. Properties of FLC-4-9 mixtures (at 25°C)

[0413]

[0414]

[0415] Example 15

[0416] Table 26. Composition of FLC-4-10 mixture

[0417]

[0418] Table 27. Properties of FLC-4-10 mixtures (at 25°C)

[0419]

[0420] Example 16

[0421] Table 28. Composition of FLC-4-11 mixture

[0422]

[0423] Table 29. Properties of FLC-4-11 mixtures (at 25°C)

[0424]

[0425] The examples demonstrate the importance of highly polar groups at the chiral center (such as CF3 in FLC-4-1, see Example 28): their variation compared to the nonpolar CH3 group reduced spontaneous polarization by about 2.4 times and HTP by about 1.6 times (compared to Example 28).

[0426] Example 17. Comparative Example

[0427] Table 30. Composition of FLC-4-12 mixture

[0428]

[0429] Table 31. Properties of FLC-4-12 mixtures (at 25°C)

[0430]

[0431]

[0432] Comparative examples showing results for known chiral components are presented. Examples illustrate the effect of the movement of polar groups in the central nucleus of a chiral component molecule toward its center on the tilt angle; see Example 29.

[0433] Example 18 Comparative Example

[0434] Table 32. Composition of FLC-4-13 mixture

[0435]

[0436] Table 33. Properties of FLC-4-13 mixtures (at 25°C)

[0437]

[0438] Comparative examples showing results for known chiral components are presented. Examples illustrate the effect of the movement of polar groups in the central nucleus of a chiral component molecule toward its center on the tilt angle; see Example 28.

[0439] Example 19 Comparative Example

[0440] Table 34. Composition of FLC-4-14 mixture

[0441]

[0442]

[0443] Table 35. Properties of FLC-4-14 mixtures (at 25°C)

[0444]

[0445] Comparative examples showing results for known chiral components.

[0446] The example shows:

[0447] - Importance of highly polar groups in chiral centers (e.g., CF3 in FLC-4-1, see Example 28): their variation compared to nonpolar CH3 reduces spontaneous polarization by approximately 1.2 times.

[0448] - The effect of polar groups in the molecular central nucleus on the tilt angle, see Example 28.

[0449] Example 20

[0450] Table 36. Composition of FLC-4-15 mixture

[0451]

[0452] Table 37. Properties of FLC-4-15 mixtures (at 25°C)

[0453]

[0454]

[0455] The examples illustrate the effect of the terminal chiral unit type. Clearly, two different chiral units induce Ps (high value) with the same sign and HTP (helically unwound to 240 nm) with opposite signs, see Example 28.

[0456] Example 21

[0457] Table 38. Composition of FLC-4-16 mixture

[0458]

[0459] Table 39. Properties of FLC-4-16 mixtures (at 25°C)

[0460]

[0461] The examples illustrate the effect of the properties and length of the central core in the chiral component; see Example 28. Due to the high melting point, the chiral component is not sufficiently soluble in the bulk, and even at 14 mol%, the melting point of the mixture increases to 29°C. Furthermore, the inclination angle is too low, clearly because the molecules in the chiral component are significantly longer than those in the bulk.

[0462] Example 22

[0463] Table 40. Composition of FLC-4-17 mixture

[0464]

[0465] Table 41. Properties of FLC-4-17 mixtures (at 25°C)

[0466]

[0467] The examples illustrate the effect of the properties and length of the central core in the chiral component; see Example 28. Because the chiral component molecule is shorter than that in the host, HTP decreases, and the induced pitch is excessively large. The chiral component is also incompatible with the host, causing TSmC* to drop to 75°C.

[0468] Example 23

[0469] Table 42. Composition of FLC-4-18 mixture

[0470]

[0471] Table 43. Properties of FLC-4-18 mixtures (at 25°C)

[0472]

[0473] The examples illustrate the effect of the properties and length of the central core in the chiral component; see Example 28. Clearly, because the chiral component molecule is shorter than the host, HTP is significantly reduced, and the induced p0 is excessively large. The chiral component also exhibits poor compatibility with the host, resulting in a decrease in TSmC* to 32°.

[0474] Example 24

[0475] Table 44. Composition of FLC-6-1 mixture

[0476]

[0477] Table 45. Properties of FLC-6-1 mixtures (at 25°C)

[0478]

[0479] Example 25

[0480] Table 46. Composition of FLC-6-2 mixture

[0481]

[0482] Table 47. Properties of FLC-6-2 mixtures (at 25°C)

[0483]

[0484]

[0485] Example 26

[0486] Table 48. Composition of FLC-6-3 mixture

[0487]

[0488] Table 49. Properties of FLC-6-3 mixtures (at 25°C)

[0489]

[0490] The examples illustrate the effect of terminal alkyl chain length on pitch and tilt angle; see Example 46.

[0491] Example 27

[0492] Table 50. Composition of FLC-6-4 mixture

[0493]

[0494]

[0495] Table 51. Properties of FLC-6-4 mixtures (at 25°C)

[0496]

[0497] Example 28 Comparative Example

[0498] Table 52. Composition of FLC-6-5 mixture

[0499]

[0500] Table 53. Properties of FLC-6-5 mixtures (at 25°C)

[0501]

[0502]

[0503] Comparative examples showing results for known chiral components.

[0504] The examples illustrate the effect of central core substitution on tilt angle; see Example 46.

[0505] Example 29 Comparative Example

[0506] Table 54. Composition of FLC-6-6 mixture

[0507]

[0508] Table 55. Properties of FLC-6-6 mixtures (at 25°C)

[0509]

[0510] Comparative examples showing results for known chiral components are presented. Examples illustrating the effect of central core substitution on θ are shown in Example 46.

[0511] Example 30

[0512] Table 56. Composition of the FLC-DFT-1 mixture

[0513]

[0514]

[0515] Table 57. Properties of the FLC-DFT-1 mixture (at 25°C)

[0516]

[0517] The example demonstrates the effect of the subject.

[0518] The chiral component has poor compatibility with the host DFT – TSmC* drops to 36°C and HTP decreases by more than 2.5 times.

[0519] Example 53

[0520] Table 58. Composition of FLC-3DFT-1 mixture

[0521]

[0522] Table 59. Properties of the FLC-3DFT-1 mixture (at 25°C)

[0523]

[0524] The example demonstrates the effect of the subject.

[0525] The chiral component has poor compatibility with the host DFT – TSmC* drops to 61°C and HTP decreases by more than 1.5 times.

[0526] Example 31

[0527] Table 60. Composition of FLC-3DFT-2 mixture

[0528]

[0529] Table 61. Properties of the FLC-3DFT-2 mixture (at 25°C)

[0530] Inclination angle, θ, degrees 36.5 - Below optimal value <![CDATA[Pitch, p0, nm]]> 212 – Exceeds the optimal value

[0531] The example demonstrates the effect of the subject.

[0532] The chiral component has poor compatibility with the host DFT – TSmC* drops to 55°C and HTP decreases by more than 2 times.

[0533] Example 32

[0534] Table 62. Composition of the FLC-DFT-2 mixture

[0535]

[0536] Table 63. Properties of the FLC-DFT-2 mixture (at 25°C)

[0537]

[0538] The example demonstrates the effect of the subject.

[0539] The chiral component exhibits poor compatibility with the bulk DFT – TSmC* drops to 55°C and HTP decreases by more than 1.5 times. The mixture is unstable during storage, with some chiral components precipitating over time.

[0540] Summary of Examples

[0541] The key parameters of FLC materials are optimized by changing the chemical structure of the components and carefully matching the lengths of the central core and terminal chains of the chiral and achiral components.

[0542] As can be seen from the examples, sufficiently high spontaneous polarization and acceptable short pitch were observed in mixtures in which the chiral component has a combination of highly polar groups (O and CF3) at the chiral center with adjacent ester functions. Chiral compounds having only polar ether functional groups (-O- groups) and low-polarity CH3 groups at the chiral center showed significantly less distortion and polarization.

[0543] Sufficiently long terminal alkyl groups in the chiral component (longer than similar groups in the chiral host) also favor high twist and short pitch. However, longer terminal alkyl groups reduce the tilt angle. Conversely, when the terminal alkyl chain is shorter, HTP decreases slightly while the tilt angle increases.

[0544] In all embodiments, chiral compounds with polar atoms (one or more side fluorine or heterocyclic N atoms) in the central nucleus induce a higher tilt angle than those not substituted in the nuclear analogue. This effect is more pronounced when these polar groups are located at the ends of the central nucleus rather than in the middle.

[0545] Among suitable achiral hosts, biphenylpyrimidine (BPP) is preferred over laterally fluorinated terphenyl (DFT) or bicyclic phenylpyrimidine (PP-7). Individually, the set of chiral components proposed by the DFT host appears to be less compatible than BPP. The DFT host significantly reduces T... SmC* The upper limit of the phase, while this temperature varies only slightly in mixtures of CC and BPP, and in some cases, it may even increase. However, the DTF body can be used with BPP at medium to low concentrations (about 25 mol.%) to lower the melting point of the mixture.

[0546] In the case of PP7 as the main component, when used alone with chiral components, the HTP is not low, and the induced helical structure is insufficient for DHFLC. In mixtures of PP7 and BPP, the melting point reduction effect only becomes significant at higher PP7 contents, where its effect on HTP reduction is dominant.

[0547] Industrial applicability

[0548] The disclosed compounds and liquid crystal compositions can be used in electro-optic devices utilizing the DHFLC effect. This is applicable to various industries, such as the display and photonics industries, where the compounds and liquid crystal compositions can be used in LCD displays.

[0549] Obviously, after reading the above disclosure, those skilled in the art will clearly see various other modifications and adjustments to the invention without departing from the spirit and scope of the invention, and it is intended that all such modifications and adjustments be incorporated herein.

[0550] Key parameters (FLC) of this invention and key parameters of current technology

[0551] Table 64. Comparison of FLC with other NLC technologies

[0552] Material Response time spacing Alignment Contrast hysteresis DHFLCs (This Invention) ~100μs Component gaps flat ～800:1 none SSFLC ~50μs Component gaps flat ～100:1 yes Kerr effect FLC ~100μs Component gaps vertical ～1000:1 none ESHFLC ~50μs ≤ Component gap flat ～10000:1 none

[0553] References:

[0554] [1]Sven T.Lagerwall, "Ferroelectric Liquid Crystal Displays andDevices", in Handbook of Liquid Crystals: 8Volume Set, Second Edition. Edited by J.W.Goodby, PJCollings, T.Kato, C.Tschierske, HFGleeson, and P.Raynes, 2014Wiley-VCH Verlag gmbH&Co.KGaA.Published 2014by Wiley-VCH Verlag gmbH&Co.KGaA., Volume 8. Applications of Liquid Crystals, Part I. Display Devices, pp1-25.

[0555] [2]Coe-Sullivan, S., SID Symposium Digest of Technical Papers, WileyOnline Library 2016, pp.239-240.

[0556] [3]Gardiner, DJ, Morris, SM, Castles, F., Qasim, MM, Kim, WS, Choi, SS, Park, HJ, Chung, IJ, Coles, HJ (2011). Applied Physics Letters, 98, 263508.

[0557] [4]Lagerwall,S.T.(2004).Ferroelectric and antiferroelectric liquidcrystals.Ferroelectrics,301,15。

[0558] [5]Xu,S.,Ren,H.,Wu,S.T.(2012).Optics Express,20,28518。

[0559] [6]Ming,Y.,Chen,P.et al.(2017).Tailoring the photon spin vialight–matter interaction in liquid-crystal-based twistingstructures.QuantumMaterials,2(1),6。

[0560] [7]Okaichi,N.,Kawakita,M.,Sasaki,H.,Watanabe,H.,Mishina,T.(2018).“High-quality direct-view display combining multiple integral 3Dimages”Journal of the Society for Information Display,1-12,2018。

[0561] [8]A.K.Srivastava,V.G.Chigrinov,H.S.Kwok,Ferroelectricliquidcrystals:Excellent tool for modern displays and photonics,J.Soc.Inform.Display 23(2015)253-272。

[0562] [9]A.K.Srivastava,V.V.Vashchenko Ferroelectric liquid crystalsandtheir application in modern displaysand photonic devices,Boo chapter。

[0563]

[10] V.Mikhailenko,A.Krivoshey,E.Pozhidaev,E.Popova,A.Fedoryako,S.Gamzaeva,V.Barbashov,A.K.Srivastava,H.S.Kwok,V.Vashchenko,The nano-scalepitch ferroelectric liquid crystal materials formodern display and photonicapplication employing highly effective chiralcomponents:trifluoro-methylalkyldiesters of p-terphenyl-dicarboxylic acid,J.Mol.Liq.281(2019)186-195。

Claims

1. A ferroelectric liquid crystal (FLC) material for a deformable spiral ferroelectric liquid crystal (DHFLC) electro-optic mode device, comprising at least two components and exhibiting optimal electro-optic properties, wherein at least one FLC component is a chiral compound of formula (I): （I）， in: n is 0 or 1; R 1 R 2 R 3 and R 4 Each of the following is independently 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by one or more substituents selected from the group consisting of halogens and methyl groups, provided that the ring R 1 and ring R 4 None of them are unsubstituted 1,4-phenylene; A 1 and A 2 It does not exist independently, which means that the group W 1 or W 2 Directly connected to ring R 1 or ring R 4 Or choose the group consisting of -O-, -S- and esters; and W 1 and W 2 Independently chiral alkyl C m H 2m+1 or chiral alkenyl C m H 2m Where m = 4-14, and optionally one or more hydrogens are independently substituted by F, Cl or cyano groups, and optionally one or more CH2 groups are independently substituted by CF2, O or -CO- groups, provided that the two O atoms are not bonded together; where W 1 and W 2 Independently, at one or more chiral centers, it is partially substituted by at least one group selected from the group consisting of F, Cl, trifluoromethyl, O, and cyano. The FLC material further comprises at least one chiral smectic C liquid crystal compound of formula (II): (II); in: R 5 R 6 R 7 and R 8 Independently, it is 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by at least one substituent selected from the group consisting of halogen and methyl; k is 0 or 1; A 3 and A 4 Independently absent or selected from the group consisting of -O-, -S-, and esters; and W 3 and W 4 Independently alkyl C m H 2m+1 or alkenyl C m H 2m , where m = 4-12, and optionally one or more hydrogens are independently substituted by F, and optionally one or more CH2 are independently substituted by CF2, O or -CO- groups, provided that the two O atoms are not connected together.

2. The FLC material according to claim 1, wherein W 1 and W 2 Choose independently from the following groups: in: X is fluorine, chlorine, or cyanide; and p is an integer in the range of 2 to 10.

3. The FLC material according to claim 1, wherein the chiral compound of formula (I) has formula (Ia): (It), Where R 3 W 1 and W 2 As defined in claim 1.

4. The FLC material according to claim 1, wherein the chiral compound of formula (I) has formula (Ib): (One), Where R 3 W 1 and W 2 As defined in claim 1.

5. The FLC material according to claim 1, wherein the chiral compound of formula (I) has formula (Ic): (Ic), Where R 3 W 1 and W 2 As defined in claim 1.

6. The FLC material according to claim 1, wherein the chiral compound of formula (I) has formula (Id): (Id), Where R 3 W 1 and W 2 As defined in claim 1.

7. The FLC material according to claim 1, wherein the chiral compound of formula (I) has formula (Ie): (Ie), Where R 3 W 1 and W 2 As defined in claim 1.

8. The FLC material according to claim 1, wherein the chiral compound of formula (I) has formula (If): (If), Where R 3 W 1 and W 2 As defined in claim 1.

9. The FLC material according to claim 1, wherein the chiral compound of formula (I) is selected from the group consisting of: , , , , and .

10. The FLC material according to claim 1, wherein the chiral smectic C liquid crystal compound of formula (II) has formula (IIa): (IIa), in: R 11 and R 12 Independently 1,4-phenylene, pyrimidin-2,5-diyl, or pyridine-2,5-diyl, wherein the 1,4-phenylene, pyrimidin-2,5-diyl, and pyridine-2,5-diyl are optionally substituted by at least one substituent selected from the group consisting of halogen and methyl; and W 3 A 4 and W 4 As defined in claim 1.

11. The FLC material according to claim 1, wherein the achiral smectic C liquid crystal compound of formula (II) is selected from the group consisting of: , , , , , , , and .

12. The FLC material according to claim 1, wherein W 1 and W 2 The average length is greater than W 3 and W 4 The average length.

13. The FLC material according to claim 1, wherein W 1 and W 2 The average length is equal to W 3 and W 4 The average length is W 3 and W 4 It is at most twice the average length.

14. The FLC material according to claim 1, wherein R 1 R 2 R 3 and R 4 The total number of rings in the ring is equal to R. 5 R 6 R 7 and R 8 The total number of rings in the ring.

15. The FLC material according to claim 1, wherein the chiral compound of formula (I) and the achiral smectic C liquid crystal compound of formula (II) have a molar ratio in the range of 10:90 to 40:

60.

16. The FLC material according to claim 1, wherein the chiral compound of formula (I) has a concentration of less than 20 mol% based on the total moles of the FLC material, and wherein the FLC material has a concentration greater than 50 nC / cm² at standard ambient temperature and pressure. 2 Spontaneous polarization.

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