Liquid crystal compound with diphenylacetylene skeleton and related liquid crystal composition

Abstract

The invention discloses a bis (diphenylacetylene) liquid crystal compound and a related liquid crystal composition. The structure of the liquid crystal compound is shown as a general formula I, and in the general formula I, R is alkyl with the carbon atom number of 1-10, alkoxy with the carbon atom number of 1-10 and alkylthio with the carbon atom number of 1-10; x is methyl or ethyl. The liquid crystal composition comprises a liquid crystal compound with a structure shown in a general formula I. The liquid crystal compound and the composition have the advantages of wider nematic phase temperature zone and high birefringence. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid crystal materials, and in particular relates to a liquid crystal compound, a liquid crystal composition, a liquid crystal high-frequency component, and a liquid crystal optical element having a bis-diphenylacetylene skeleton. Background Art

[0002] Liquid crystal materials have been widely used in optoelectronic display devices, such as various LCD TVs, desktop LCD monitors, mobile display terminals, etc. In recent years, with the continuous development of microwave and terahertz communication, optical communication, laser phased array and other technologies, there is an urgent need for liquid crystal materials with high birefringence. The higher the birefringence (Δn) of the liquid crystal, the greater the dielectric anisotropy value in the microwave (1-100G) and terahertz bands. In addition, in liquid crystal devices such as optical communication and laser phased array, the use of liquid crystals with high birefringence (Δn) can greatly shorten the response time while ensuring the optical phase modulation amount. Therefore, it is hoped that there will be liquid crystal materials with a birefringence > 0.40, or even a birefringence > 0.50, to improve the working performance of the device.

[0003] In order to improve the birefringence of liquid crystal materials, it is necessary to introduce a structure with a long conjugated chain into the liquid crystal molecules. For example, the molecular skeleton adopts a long conjugated structure of biphenyl and diphenylacetylene; the introduction of conjugated groups at the molecular ends, such as isothiocyanate (-NCS) and cyano (-CN), can further improve the birefringence.

[0004] Patents US20200347301, WO2021037962A1, WO2021069535A1, and WO2022008474A1 disclose compositions based on isothiocyanate liquid crystals, and their high-frequency dielectric properties and optical properties; the birefringence of the liquid crystal compositions is mostly between 0.3 and 0.4; key performance parameters such as birefringence and dielectric adjustability at high frequencies still need to be improved.

[0005] As the birefringence index of isothiocyanate-based liquid crystal compositions increases, the low-temperature performance decreases significantly. For example, in the paper "High Optical Anisotropy Nematic Single Compounds and Mixtures. Transactions on Electrical and Electronic Materials, 2012, 13(1):2-5", a liquid crystal with a birefringence index of 0.50 is presented, but it crystallizes at a low temperature of 9 degrees, which cannot meet the ambient temperature requirements of actual devices.

[0006] In the paper “Design of new super-high birefringent isothiocyanatobistolanes-synthesis and properties. Liquid Crystals, 2017, 44(9): 1462-1467”, a liquid crystal compound combining a bis(diphenylacetylene) skeleton with isothiocyanate (-NCS) and having lateral ethyl substitution was reported. The structural formula and liquid crystal phase transition temperature are as follows:

[0007]

[0008] This type of liquid crystal has a highly conjugated bis(diphenylacetylene) skeleton and a birefringence of more than 0.5, and has very good application prospects in microwave devices and optical components. Although bis(diphenylacetylene) liquid crystals have a very high birefringence, they still have problems in practical applications, such as poor low temperature resistance and easy crystallization.

[0009] Patent CN108431174A discloses a diphenylacetylene / bisdiphenylacetylene liquid crystal composition with an alkylthio structure. Although the birefringence is greater than 0.45, its low-temperature performance is still not ideal; in terms of low-temperature performance, it can only reach 10 to 30°C, which is obviously far from the requirement of wide temperature range operation of actual devices.

[0010] In order to further meet the working performance requirements of microwave, optical and other components, it is urgently necessary to research and develop new liquid crystal molecular structures and liquid crystal compositions that have high birefringence, wide nematic phase temperature range and good compatibility. Summary of the invention

[0011] In order to overcome the defects or shortcomings in the background technology, the present invention provides a novel liquid crystal compound having a bis(diphenylethene) skeleton.

[0012] In order to achieve the above task, the liquid crystal compound containing a bis(phenylacetylene) skeleton provided by the present invention has a structure as shown in general formula I:

[0013]

[0014] Wherein: R is an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms or an alkylthio group having 1 to 10 carbon atoms; X is a methyl group or an ethyl group.

[0015] The preferred structure of the bis(phenylacetylene) skeleton liquid crystal compound of the present invention is shown in the following general formula:

[0016]

[0017] In formulas IA to I-F, R1 of each compound is independently selected from an alkyl group having 1 to 7 carbon atoms.

[0018] The bis-diphenylacetylene skeleton compound of the present invention, compared with similar liquid crystal compounds disclosed in the prior art, obtains significantly improved liquid crystal phase transition temperature characteristics, an expanded nematic phase temperature range, a lower crystallization temperature and good low-temperature miscibility by adjusting the lateral methyl or ethyl substitution sites. At the same time, the liquid crystal compound of the present invention also maintains the advantage of ultra-high birefringence. The bis-diphenylacetylene skeleton compound of the present invention solves the long-standing problem that ultra-high birefringence liquid crystals are easy to crystallize at low temperatures.

[0019] The present invention also provides a liquid crystal composition, which comprises one or more liquid crystal compounds selected from the group consisting of the compounds represented by the general structural formula I. Optionally, the mass percentage of the compound represented by the formula I in the liquid crystal composition of the present invention is 1 to 100%.

[0020] The liquid crystal composition of the present invention preferably further contains one or more liquid crystal compounds selected from the group consisting of the liquid crystal compounds represented by the general structural formulae IA to IF.

[0021] In a preferred embodiment of the present invention, the liquid crystal composition comprises a plurality of compounds selected from the group consisting of compounds of formula I.

[0022] An optional solution is that the mass percentage of the compound represented by formula I in the liquid crystal composition is 1% to 100%, preferably 5% to 90%, and more preferably 10% to 50%.

[0023] In another preferred embodiment of the present invention, the liquid crystal composition further comprises one or more compounds selected from the group consisting of compounds of general structural formula II:

[0024]

[0025] Among them, R2 is an alkyl group with 1 to 10 carbon atoms, an alkoxy group with 1 to 10 carbon atoms, an alkylthio group with 1 to 10 carbon atoms, an alkenyl group with 2 to 10 carbon atoms, or an alkenyloxy group with 2 to 10 carbon atoms; Ring A, Ring B, and Ring C are each independently represented by a benzene ring, cyclohexane, or cyclohexene, wherein the hydrogen atoms on the benzene ring may be replaced by fluorine, chlorine, methyl, or ethyl; Z1 and Z2 are each independently represented by a single bond, -C≡C-, -CH=CH-, or -CF=CF-; and n=0, 1.

[0026] More preferably, the compound of general formula II is a liquid crystal compound shown in II-A to II-H:

[0027]

[0028] In formula II-A to II-H, X in each structural formula is a fluorine atom.

[0029] Optionally, the liquid crystal compound of the present invention contains 0 to 90% by mass of the compound represented by Formula II, preferably 5 to 80%, particularly preferably 10 to 70%.

[0030] The liquid crystal composition according to the present invention may further contain 0.001-1% of additives, such as hindered phenol antioxidants, hindered amine light stabilizers, etc. The hindered phenol antioxidant is preferably selected from the following structures:

[0031]

[0032] wherein R' is an alkyl group or an alkoxy group having 1 to 9 carbon atoms.

[0033] The hindered amine light stabilizer is preferably selected from the following structures:

[0034]

[0035] The preferred amount of hindered phenol antioxidants and amine light stabilizers added is 0.01% to 0.5%, more preferably 0.02% to 0.2%.

[0036] The liquid crystal composition of the present invention may further comprise one or more chiral additives, the content of which is 0.01% to 1%, preferably 0.1% to 0.5%. The chiral additives are preferably selected from the following structures:

[0037]

[0038] wherein R″ is an alkyl group having 1 to 9 carbon atoms or an alkoxy group having 1 to 9 carbon atoms.

[0039] In a specific embodiment, the liquid crystal composition of the present invention is composed of a plurality of compounds, preferably 3 to 20 compounds, more preferably 5 to 18 and more preferably 7 to 15 compounds. These compounds can be mixed in a conventional manner: various compounds are weighed according to a predetermined mass ratio, and then heated and heated, and mixed homogeneously by stirring methods such as magnetic stirring or ultrasonic stirring until each component is completely dissolved; and then filtered to obtain. The liquid crystal composition can also be prepared in other conventional ways, such as using a so-called premix, or using a so-called "multi-bottle" system, in which the components themselves are ready-to-use mixtures.

[0040] The performance of liquid crystal at high frequencies was tested using the test method reported in the literature: Penirschke, A. (2004). Cavityperturbation method for characterization of liquid crystals up to 35 GHz. Microwave Conference,2004.34th European Specifically, liquid crystal is introduced into a polytetrafluoroethylene (PTFE) or fused silica capillary, and the filled capillary is introduced into the middle of a chamber with a resonance frequency of 19 GHz. Then an input signal source is applied, and the result of the output signal is recorded with a vector network analyzer. The changes in the resonance frequency and Q factor between the capillary filled with liquid crystal and the blank capillary are measured, and the dielectric constant and loss tangent are calculated. The dielectric constant components perpendicular and parallel to the liquid crystal director are obtained by the alignment of the liquid crystal in a magnetic field, and the direction of the magnetic field is set accordingly, and then rotated 90° accordingly.

[0041] The preferred liquid crystal composition of the present invention has a tuning rate τ≥0.34, more preferably ≥0.35. The vertical dielectric loss tanδ of the preferred liquid crystal material is ⊥ ≤0.010, more preferably tanδ ⊥ ≤0.008; material quality factor η≥40, preferably η≥50.

[0042] The preferred nematic phase temperature range of the liquid crystal composition of the present invention is 10 to 120° C. or a wider temperature range, and the more preferred nematic phase temperature range is -10 to 140° C. or a wider temperature range.

[0043] The liquid crystal composition according to the present invention is very suitable for preparing microwave components, such as phase shifters that can be tuned by an external magnetic field or electric field. These phase shifters can work in UHF-band (0.3-1GHz), L-band (1-2GHz), S-band (2-4GHz), C-band (4-8GHz), X-band (8-12GHz), Ku-band (12-18GHz), K-band (18-27GHz), Ka-band (27-40GHz), V-band (50-75GHz), W-band (75-110GHz) and up to 1THz. The construction of the phase shifter according to the present application is known to experts. Typically, a loaded line phase shifter, an inverted microstrip line, a fin line (Finline) phase shifter is used, preferably an antipodal fin line phase shifter, a slotted phase shifter, a microstrip line phase shifter or a coplanar waveguide (CPW) phase shifter. These components enable reconfigurable antenna arrays.

[0044] The liquid crystal composition according to the present invention has a relatively high birefringence (Δn). The preferred liquid crystal composition according to the present invention has a Δn≥0.45 at 25° C. and 589 nm, and more preferably a Δn≥0.48.

[0045] The liquid crystal composition according to the present invention is suitable for manufacturing liquid crystal optical elements, including phase modulation devices, gratings, wavelength selective switches (WSS), etc., due to its characteristics such as large birefringence and low viscosity.

[0046] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is:

[0047] The liquid crystal compound of the present invention has the advantages of a wider nematic phase, a lower crystallization temperature, and good compatibility; at the same time, it also retains the advantages of high birefringence and large dielectric tunability common to bis-diphenylacetylene liquid crystals. The composition based on the liquid crystal compound of the present invention obtains a larger dielectric tuning rate and extremely low dielectric loss at high frequencies; and has the advantages of a larger optical birefringence and a wide operating temperature range. DETAILED DESCRIPTION

[0048] Unless otherwise specified, the scientific and technical terms and methods in this document are based on the understanding of ordinary technicians in the relevant fields or are implemented using existing relevant methods.

[0049] The present invention is further described in detail below in conjunction with specific embodiments.

[0050] It should be noted that the detailed test methods for the physical properties and photoelectric properties involved in the present invention are as follows:

[0051] (1) Liquid crystal phase transition temperature:

[0052] Differential scanning calorimetry (DSC) was used: under nitrogen atmosphere, the heating (cooling) rate was set to 5°C / min.

[0053] Polarized light hot stage method: Place the liquid crystal sample in a cross-polarized light microscope hot stage and set the heating rate to 2°C / min. Observe the texture image of the liquid crystal phase transition under a polarized light microscope to determine the liquid crystal phase state.

[0054] (2) Birefringence (Δn): Liquid crystal monomers were added to the basic formula HOST at a mass ratio of 15:85%, and heated to mix well. An Abbe refractometer was used at a constant temperature of 25°C and a light source of 589 nm to measure the birefringence of ordinary light (n o ) and extraordinary light (n e ) and extrapolate to obtain the birefringence.

[0055] (3) Dielectric constant (Δε, 1KHz): Add liquid crystal monomer to the basic formula HOST at a mass ratio of 15:85%, heat and mix evenly. Test with an LCR meter at a constant temperature of 25°C. Δε = ε ∥ -ε ⊥ , that is, the dielectric constant along the long axis of the molecule (ε ∥ ) and the dielectric constant in the molecular short axis direction (ε ⊥ ) is extrapolated to obtain the dielectric anisotropy value Δε.

[0056] (4) Rotational viscosity (γ1): Liquid crystal monomers were added to the basic formula HOST at a mass ratio of 15:85%, and heated and mixed evenly. Under a constant temperature of 25°C, a voltage was applied to the liquid crystal test box to test the transient current value Ip of the liquid crystal molecules deflected by the electric field, and the rotational viscosity γ1 was calculated and extrapolated.

[0057] (5) Dielectric constant and dielectric loss (Δε, tanδ, 19GHz): Add liquid crystal monomers to the basic formula M0 at a mass ratio of 15:85%, and heat and mix evenly. Under a constant temperature of 25°C, pour the liquid crystal into a polytetrafluoroethylene (PTFE) or fused silica capillary, and insert the capillary filled with liquid crystal into the middle of the resonant chamber. Then apply the input signal source and use a vector network analyzer to record the output signal results. Measure the changes in the resonant frequency and Q factor between the capillary filled with liquid crystal and the blank capillary, and calculate the dielectric constant and loss tangent. The dielectric constant components perpendicular and parallel to the liquid crystal director are obtained by the orientation of the liquid crystal in the magnetic field, and the direction of the magnetic field is set accordingly, and then rotated 90° accordingly.

[0058] (6) Low temperature storage temperature (LTS): Take 1g of the liquid crystal sample and place it in a transparent borosilicate glass bottle, store it in a low temperature freezer, and observe the temperature at which crystallization occurs. If no crystals are precipitated at a low temperature of -20°C, then LTS ≤ -20°C.

[0059] (7) Elastic constant (K 11 , K 33 ): Under the condition of 25℃ constant temperature, the capacitance-voltage (CV) curve of liquid crystal is tested and K is obtained by fitting. 11 and K 33 .

[0060] (8) Tuning rate (τ): Adopted from the literature Penirschke, A. (2004). Cavity perturbation method for characterization of liquid crystals up to 35 GHz. Microwave Conference, 2004.34th European . The related methods disclosed in .

[0061] In the following embodiments, the basic formula HOST is obtained by uniformly mixing the following three monomer liquid crystals in a mass ratio of 1:1:1.

[0062]

[0063] Description of the codes involved in this article:

[0064] Table 1 Physical parameters

[0065]

[0066]

[0067] Liquid crystal phase transition temperature: C represents melting point, S represents smectic phase, N represents nematic phase, and I represents liquid state.

[0068] Table 2 Structural abbreviations

[0069]

[0070] Table 2 Examples of abbreviations

[0071]

[0072] The synthesis of the liquid crystal compound represented by the general formula I of the present invention can be based on the existing relevant synthesis methods, and the corresponding raw materials can be selected for synthesis. The synthesis route can refer to the synthesis route of the compound in the following embodiment 1, and different target products can be obtained by replacing the corresponding reactants. The components involved in the following examples except the liquid crystal compound represented by formula I can be obtained using the existing relevant methods or purchased from commercial products.

[0073] Embodiment 1:

[0074] This example is the synthesis of 4-((4-(propylpentyl)phenyl)ethynyl)-3-ethyl-1-((4-isothiocyanatephenyl)ethynyl)benzene, and the structural formula is as follows:

[0075]

[0076] Its synthetic route is as follows:

[0077]

[0078] The specific method is as follows:

[0079] (1) Under nitrogen protection, add 15.6g 2-ethyl-4-bromo-1-iodobenzene, 100mL triethylamine, 0.35g ditriphenylphosphine palladium chloride, 0.29g cuprous iodide, and 0.39g triphenylphosphine to the reactor, and add 30mL triethylamine solution containing 7.2g 4-n-propylphenylacetylene dropwise at room temperature. After the addition is complete, react at room temperature for 4h; heat to 50°C, and then add 30mL triethylamine solution containing 5.9g trimethylsilylacetylene dropwise. After the addition is complete, continue to react for 4h; filter, concentrate the filtrate to dryness, add 100mL toluene, wash with water, dry, and remove toluene under reduced pressure. The product is passed through a silica gel column and eluted with n-heptane. After concentration, 15.5g of an oily liquid is obtained;

[0080] (2) 15.5 g of the liquid obtained in step (1) and 200 mL of ethanol were added to a new reaction vessel, and 1.5 g of potassium carbonate was added. The mixture was stirred at room temperature for 5 h. The ethanol was evaporated under reduced pressure, and 100 mL of toluene was added for extraction. The organic layer was washed with water until neutral, and the solvent was removed under reduced pressure to obtain 11.6 g of 2-ethyl-4-ethynyl-1-((4-n-propylphenyl)ethynyl)benzene as an oily liquid.

[0081] (3) Under nitrogen protection, add 4.4g of p-iodoaniline, 0.14g of ditriphenylphosphine palladium chloride, 0.12g of cuprous iodide, and 0.16g of triphenylphosphine to another reactor, raise the temperature to 50°C, slowly drop 60mL of triethylamine solution containing 5.4g of 2-ethyl-4-ethynyl-1-((4-n-propylphenyl)ethynyl)benzene, and keep the temperature for 4h after the drop is complete; cool to room temperature, filter, concentrate the filtrate to dryness, add 100mL of toluene, wash with water, dry, and remove toluene under reduced pressure. Recrystallize with toluene to obtain 5.5g of brown solid 4-((3-ethyl-4-((4-n-propylphenyl)ethynyl)phenyl)ethynyl)aniline;

[0082] (4) The product obtained in step (3) was dissolved in 60 mL of tetrahydrofuran, 2.6 g of thiophosgene was added dropwise at room temperature, and the reaction was stirred for 4 h; the reaction solution was concentrated, extracted with toluene, washed with water until neutral, and toluene was removed under reduced pressure. The product was passed through a silica gel column and eluted with n-heptane. The eluate was concentrated to dryness under reduced pressure, and n-heptane was repeatedly recrystallized to obtain 4.4 g of 4-((4-(propylpentyl)phenyl)ethynyl)-3-ethyl-1-((4-isothiocyanatephenyl)ethynyl)benzene as a white solid.

[0083] The product structure identification data are as follows:

[0084] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.954 (t, 3H, J = 7.5Hz), 1.312 (t, 3H, J = 7.5Hz), 1.612 ~ 1.686 (m, 2H), 2.603 ( t,2H,J=7.5Hz),2.880(q,2H,J=7.5Hz),7.162~7.201(m,4H),7.310~7.329(m,1H),7.399~7.503(m,6H).

[0085] 13C NMR (125MHz, CDCl3) δ (ppm): 13.8, 14.6, 24.4, 27.6, 38.0, 87.2, 89.5, 91.6, 95.2, 120.5, 122.3, 122.4, 123.1,125.8(2C),128.6(2C),128.8,131.0,131.1,131.4(2C),132.1,132.8(2C),136.8,143.4,146.2.

[0086] DSC: C 98.0N 181.3I.

[0087] The compound was added into the basic formula HOST at a ratio of 15%, and no crystallization occurred when stored at room temperature, indicating that the compound had good compatibility.

[0088] Further testing revealed that the compound had a birefringence of Δn=0.575, γ1=713.4 mPa·s, and Δε(1 kHz)=12.5.

[0089] Embodiment 2:

[0090] This embodiment is 4-((4-(n-butyl)phenyl)ethynyl)-3-ethyl-1-((4-isothiocyanatephenyl)ethynyl)benzene, and the structural formula is as follows:

[0091]

[0092] Substituting 4-n-propylphenylacetylene for 4-n-butylphenylacetylene, 4-((4-(n-butyl)phenyl)ethynyl)-3-ethyl-1-((4-isothiocyanatephenyl)ethynyl)benzene was prepared in the same manner as in Example 1.

[0093] The structural identification data are as follows:

[0094] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.931 (t, 3H, J = 7.5Hz), 1.312 (t, 3H, J = 7.5Hz), 1.327 ~ 1.395 (m, 2H), 1.572 ~ 1.633 (m, 2 H), 2.625 (t, 2H, J = 7.5Hz), 2.880 (q, 2H, J = 7.5Hz), 7.164~7.202 (m, 4H), 7.311~7.329 (m, 1H), 7.399~7.503 (m, 6H).

[0095] 13C NMR (125MHz, CDCl3) δ (ppm): 14.0, 14.6, 22.3, 27.6, 33.4, 35.6, 87.2, 89.5, 91.6, 95.2, 120.4, 122.3, 122. 4,123.1,125.8(2C),128.7(2C),128.9,131.0,131.1,131.5(2C),132.1,132.8(2C),136.9,143.7,146.2.

[0096] DSC: C 86.5N 165.0I.

[0097] The compound was added to the basic formula HOST at a ratio of 15%, and there was no crystallization phenomenon when stored at room temperature, indicating that the compound had good compatibility. Further tests showed that the birefringence of the compound was Δn = 0.564, γ1 = 736 mPa·s, and Δε (1 kHz) = 11.9.

[0098] Embodiment 3:

[0099] This embodiment is 4-((4-(n-pentyl)phenyl)ethynyl)-3-ethyl-1-((4-isothiocyanatephenyl)ethynyl)benzene, and the structural formula is as follows:

[0100]

[0101] Substituting 4-n-pentylphenylacetylene for 4-n-propylphenylacetylene in Example 1, 4-((4-(n-pentyl)phenyl)ethynyl)-3-ethyl-1-((4-isothiocyanatephenyl)ethynyl)benzene was prepared in the same manner as in Example 1.

[0102] The structural identification data are as follows:

[0103] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.895 (t, 3H, J = 7.0Hz), 1.285 ~ 1.368 (m, 4H), 1.312 (t, 3H, J = 7.5Hz), 1.589 ~ 1.694 (m, 2 H), 2.617 (t, 2H, J = 7.5Hz), 2.880 (q, 2H, J = 7.5Hz), 7.163 ~ 7.207 (m, 4H), 7.311 ~ 7.330 (m, 1H), 7.399 ~ 7.509 (m, 6H).

[0104] 13C NMR (125MHz, CDCl3) δ (ppm): 14.0, 14.6, 22.5, 27.6, 31.0, 31.5, 35.9, 87.2, 89.5, 91.6, 95.2, 120.4, 122.3, 1 22.4,123.1,125.8(2C),128.6(2C),128.9,131.0,131.1,131.5(2C),132.1,132.8(2C),136.9,143.7,146.2.

[0105] DSC: C 70.2N 165.1I.

[0106] The compound was added to the basic formula at a ratio of 15%, and there was no crystallization phenomenon when stored at room temperature, indicating that the compound had good compatibility. Further testing obtained the physical property parameters of the compound: Δn = 0.546, γ1 = 758 mPa·s, Δε (1kHz) = 11.2.

[0107] Embodiment 4:

[0108] This embodiment is 4-((4-(n-heptyl)phenyl)ethynyl)-3-ethyl-1-((4-isothiocyanatephenyl)ethynyl)benzene, and the structural formula is as follows:

[0109]

[0110] Substituting 4-n-propylphenylacetylene for 4-n-heptylphenylacetylene, 4-((4-(n-heptyl)phenyl)ethynyl)-3-ethyl-1-((4-isothiocyanatephenyl)ethynyl)benzene was prepared in the same manner as in Example 1.

[0111] The structural identification data are as follows:

[0112] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.882 (t, 3H, J = 7.5Hz), 1.271 ~ 1.312 (m, 11H), 1.590 ~ 1.626 (m, 2H), 2.616 ( t,2H,J=7.5Hz),2.880(q,2H,J=7.5Hz),7.162~7.205(m,4H),7.311~7.330(m,1H),7.399~7.505(m,6H).

[0113] 13C NMR (125MHz, CDCl3) δ (ppm): 14.1, 14.6, 22.7, 27.6, 29.1, 29.2, 31.3, 31.8, 36.0, 87.2, 89.5, 91.6, 95.2, 120.4, 12 2.3,122.4,123.1,125.8(2C),128.7(2C),128.9,131.0,131.1,131.5(2C),132.1,132.8(2C),136.9,143.7,146.2.

[0114] DSC: C 67.6N 148.2I.

[0115] The compound was added to the basic formula HOST at a ratio of 15%, and there was no crystallization phenomenon when stored at room temperature, indicating that the compound had good compatibility. Further tests showed that the birefringence of the compound was Δn = 0.521, γ1 = 865 mPa·s, and Δε (1 kHz) = 10.3.

[0116] Embodiment 5:

[0117] This embodiment is 4-((4-(n-pentyl)phenyl)ethynyl)-3-methyl-1-((4-isothiocyanatephenyl)ethynyl)benzene, and the structural formula is as follows:

[0118]

[0119] The preparation method of the compound of this example is based on the preparation method of Example 1, except that 4-n-pentylphenylacetylene is substituted for 4-n-propylphenylacetylene in Example 1, and 2-methyl-4-bromo-1-iodobenzene is substituted for 2-ethyl-4-bromo-1-iodobenzene in Example 1. Other operations are performed in the same manner as in Example 1 to prepare 4-((4-(n-pentyl)phenyl)ethynyl)-3-methyl-1-((4-isothiocyanatephenyl)ethynyl)benzene.

[0120] The structural identification data are as follows:

[0121] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.895 (t, 3H, J = 7.0Hz), 1.285 ~ 1.368 (m, 4H), 1.589 ~ 1.694 (m, 2H), 2.6 17(t,2H,J=7.5Hz),2.881(s,3H),7.163~7.207(m,4H),7.311~7.330(m,1H),7.399~7.509(m,6H).

[0122] 13C NMR (125MHz, CDCl3) δ (ppm): 14.0, 14.6, 22.5, 31.0, 31.5, 35.9, 87.2, 89.5, 91.6, 95.2, 120.4, 122.3, 122. 4,123.1,125.8(2C),128.6(2C),128.9,131.0,131.1,131.5(2C),132.1,132.8(2C),136.9,143.7,146.2.

[0123] DSC: C 88.5S117.5N 234.4I.

[0124] The compound was added to the basic formula at a mass ratio of 10% and 15%, respectively. When the addition amount was 10%, there was no crystallization phenomenon when stored at room temperature, indicating that the compound had good solubility; when the addition amount was 15%, crystallization occurred when stored at room temperature.

[0125] Further testing yielded the following physical property parameters of the compound: Δn=0.575, γ1=602 mPa·s, Δε(1 kHz)=11.6.

[0126] Embodiment 6:

[0127] The mass ratio and performance parameters of the liquid crystal composition are shown in Table 4:

[0128] Table 4

[0129]

[0130]

[0131] The liquid crystal composition has an extremely high birefringence of 0.54 and maintains a nematic phase when the storage temperature is 20°C.

[0132] Embodiment 7:

[0133] The mass ratio and performance parameters of the liquid crystal composition are shown in Table 5:

[0134] Table 5

[0135]

[0136] The liquid crystal composition has an extremely high birefringence index of 0.50 and maintains a nematic phase at a storage temperature of -20°C.

[0137] Embodiment 8:

[0138] The mass ratio and performance parameters of the liquid crystal composition are shown in Table 6:

[0139] Table 6

[0140]

[0141] The liquid crystal composition has an extremely high birefringence of 0.53, and has a very large dielectric constant, very large dielectric adjustability, very low dielectric loss, and very high quality factor at a high frequency of 19 GHz.

[0142] Embodiment 9:

[0143] The mass ratio and performance parameters of the liquid crystal composition are shown in Table 7:

[0144] Table 7

[0145]

[0146]

[0147] The liquid crystal composition has a high birefringence of 0.45 and an extremely wide operating temperature range; it maintains a nematic phase when stored at -40 degrees Celsius. It has a large dielectric constant, large dielectric adjustability, low dielectric loss, and a high quality factor at a high frequency of 19 GHz.

[0148] Comparative Example 1:

[0149] The known bis(phenylacetylene) liquid crystal compounds have the following structural formula:

[0150]

[0151] DSC was used to test the liquid crystal phase transition temperature during the heating process and the cooling process.

[0152] For comparison, the compounds corresponding to Examples 1 to 5 of the present invention have the following structural formulas:

[0153]

[0154] The liquid crystal phase transition temperature test results of compounds (a) to (e) in Comparative Example 1 and the compounds of Examples 1 to 5 of the present invention are shown in Table 8 below:

[0155] Table 8

[0156]

[0157]

[0158] Compared with the compound (a) in comparative example 1, the clearing point of the liquid crystal compound in Example 1 of the present invention is increased by 5°C; the crystallization point temperature is reduced by 6°C when the temperature is lowered;

[0159] Compared with the compound (b) in comparative example 1, the clearing point of the liquid crystal compound in Example 2 of the present invention is increased by 6.9°C; the crystallization point temperature is reduced by 22.1°C when the temperature is lowered;

[0160] Compared with the compound (c) in comparative example 1, the clearing point of the liquid crystal compound in Example 3 of the present invention is increased by 8.1°C; the crystallization point temperature is reduced by 13.1°C when the temperature is lowered;

[0161] Compared with the compound (d) in comparative example 1, the clearing point of the liquid crystal compound in Example 4 of the present invention is increased by 7°C; the crystallization point temperature is reduced by 30.6°C when the temperature is lowered;

[0162] Compared with the compound (e) in comparative example 1, the melting point of the liquid crystal compound in Example 5 of the present invention is reduced by 12° C., and the clearing point is increased by 0.6° C.; when the temperature is lowered, the crystallization point temperature is reduced by 15.3° C.

[0163] The above comparative data show that the compound of the present invention not only has a higher clearing point than known liquid crystal compounds, but also has a significantly lower crystallization point temperature when the temperature is lowered, thereby obtaining better liquid crystal phase performance.

[0164] Comparative Example 2:

[0165] The mass ratio and performance parameters of the liquid crystal composition are shown in Table 9:

[0166] Table 9

[0167]

[0168]

[0169] Comparative Example 2 has similar structural components and mass ratios to Example 6; Comparative Example 2 is in a crystalline state at room temperature, and can only maintain a nematic phase when the temperature exceeds 50° C. It can be seen that Example 5 of the present invention not only has a higher clearing point, but also has a lower low-temperature crystallization temperature and has a room temperature operating temperature window.

Claims

1. A liquid crystal compound having a bis(phenylene vinyl) skeleton, characterized in that: The structure of the compound is shown in general formula I: In Formula I: R is an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms or an alkylthio group having 1 to 10 carbon atoms; and X is a methyl group or an ethyl group.

2. The liquid crystal compound according to claim 1, characterized in that The structure of the compound is shown in the general formula Ⅰ-A to Ⅰ-F: In formulas IA to I-F, R1 of each compound is independently selected from an alkyl group having 1 to 7 carbon atoms.

3. A liquid crystal composition, characterized in that: It contains one or more liquid crystal compounds selected from the group consisting of compounds shown in general structural formula I.

4. The liquid crystal composition according to claim 3, characterized in that: Calculated based on a mass ratio of 100%, the mass percentage of the liquid crystal compound represented by the general structural formula I in the liquid crystal composition is 1%-100%.

5. The liquid crystal composition according to claim 3, characterized in that: The birefringence Δn of the liquid crystal composition at 25° C. and 589 nm is ≥0.

45.

6. The liquid crystal composition according to claim 3, characterized in that: The tuning rate τ of the liquid crystal composition at 19 GHz is ≥ 0.

34.

7. The liquid crystal composition according to claim 3, characterized in that: The liquid crystal composition further contains one or more compounds selected from the group consisting of compounds of general structural formula II: In Formula II, R2 is an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkenyloxy group having 2 to 10 carbon atoms; Ring A, Ring B, and Ring C are each independently selected from a benzene ring, cyclohexane, cyclohexene, or a benzene ring in which a hydrogen atom is substituted by fluorine, chlorine, methyl, or ethyl; Z1 and Z2 each independently represent a single bond, -C≡C-, -CH=CH- or -CF=CF-; n＝0，1。 8. The liquid crystal composition according to claim 7, characterized in that: The mass percentage content of the compound represented by formula II is greater than 0 and less than or equal to 90%.

9. The liquid crystal composition according to claim 3, characterized in that: The liquid crystal composition further contains one or more of a hindered phenol antioxidant and a hindered amine light stabilizer.

10. The liquid crystal composition according to claim 3, characterized in that: The liquid crystal composition further contains a chiral additive.

11. A liquid crystal high frequency component, characterized in that: The raw materials for preparing the liquid crystal high-frequency component include any liquid crystal compound described in claim 1 or 2, or include the liquid crystal composition described in any one of claims 3-10.

12. A liquid crystal optical element, characterized in that: The raw materials for preparing the liquid crystal optical element include any liquid crystal compound described in claim 1 or 2, or include the liquid crystal composition described in any one of claims 3-10.

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