Liquid crystal compound containing 2, 5-difluorobenzyne, synthetic method and liquid crystal composition

Abstract

The invention discloses a liquid crystal compound containing 2, 5-difluorobenzyne, a synthesis method and a liquid crystal composition. The structure of the liquid crystal compound containing 2, 5-difluorobenzyne is shown as a formula I in the specification. The invention further discloses a liquid crystal composition with the structure shown in the general formula I. According to the liquid crystal compound disclosed by the invention, after two fluorine substituents are introduced into a specific position of a benzene ring, the liquid crystal compound has remarkably improved liquid crystal phase transition temperature characteristics, such as the characteristics of wide nematic phase liquid crystal temperature region, low melting point and high clearing point; the low-temperature intermiscibility is better, and the rotary viscosity is low; in addition, the low dielectric loss characteristic and the large dielectric anisotropy are achieved at the high frequency; meanwhile, the high birefringence is also realized. The method is suitable for preparing devices such as microwave antennas and liquid crystal optical devices. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid crystal materials, and specifically relates to a liquid crystal compound containing 2,5-difluorobenzyne, a liquid crystal composition, a liquid crystal high-frequency component, a liquid crystal optical element, and a synthesis method thereof. 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) band. In addition, in liquid crystal devices such as optical communication and laser phased array, the use of liquid crystals with high birefringence (Δn) can significantly shorten the response time while ensuring the amount of optical phase modulation.

[0003] In order to improve the birefringence of liquid crystal materials, it is necessary to use a long conjugated chain structure in the liquid crystal molecules. For example, the molecular skeleton adopts a long conjugated structure of biphenyl, terphenyl, quaterphenyl, and diphenylacetylene. Among them, the liquid crystal molecules containing acetylenic bonds (-C≡C-) have a higher polarizability anisotropy, so the birefringence is higher. Patent EP0377516A2 discloses a liquid crystal molecule containing two acetylenic bonds, and the structure is shown below:

[0004]

[0005] This type of compound has a relatively high melting point, resulting in poor solubility; and as the number of rings in the molecular skeleton increases, a smectic phase appears.

[0006] Patent JPH06298686A discloses fluorine-substituted liquid crystal molecules containing two alkynyl groups.

[0007] Patent CN105473686A discloses a liquid crystal molecule containing two acetylenic bonds and its application in the microwave band, wherein the benzene ring has a lateral alkyl substitution, such as a methyl group; although the lateral methyl-substituted benzylene compound has a lower dielectric loss, the rotational viscosity of this type of liquid crystal compound is relatively large and cannot meet the requirements of rapid response of microwave antennas.

[0008] In order to further meet the working performance requirements of optical, microwave and other components, it is urgently necessary to research and develop new molecular structures with wide nematic phase temperature range, good solubility, low viscosity, high birefringence and low dielectric loss. Summary of the invention

[0009] In order to overcome the defects or shortcomings in the background technology, the present invention provides a novel fluorine-substituted benzyne liquid crystal compound.

[0010] In order to achieve the above tasks, the present invention adopts the following technical solutions:

[0011] The fluorine-containing benzylene liquid crystal compound provided by the present invention has a structure as shown in general formula I:

[0012]

[0013] Wherein: R1 is an alkyl or alkoxy group having 1 to 10 carbon atoms, an alkenyl or alkenyloxy group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, or an alkyl group substituted with a cycloalkyl group, wherein the hydrogen on the carbon atom of R1 may be replaced by fluorine; R2 is an alkyl group having 1 to 3 carbon atoms; Z1 and Z2 are independently a single bond, -C≡C-, -CH=CH-, -CF=CF-, -CF2O-, -CH2CH2; Ring A and Ring B are independently a benzene ring or cyclohexane or cyclohexene, wherein the hydrogen on the benzene ring may be replaced by fluorine, chlorine, methyl or ethyl; n=0, 1 or 2.

[0014] In some preferred embodiments, Z2 is -C≡C-.

[0015] In some preferred embodiments, n=0.

[0016] In some preferred embodiments, n=1, and ring A is a benzene ring or cyclohexane.

[0017] In some preferred embodiments, R2 is methyl.

[0018] In some specific embodiments, the structure of the fluorinated benzylene liquid crystal compound of the present invention is shown in the following general formula:

[0019]

[0020] In compounds Ⅰ-1 to Ⅰ-11, R is independently an alkyl or alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, or an alkyl group substituted with a cycloalkyl group having 3 to 8 carbon atoms, and the hydrogen on the carbon atom of R may be substituted with fluorine.

[0021] The liquid crystal compound of the present invention, after introducing two fluorine substituents at specific positions of the benzene ring, obtains surprising results compared with similar liquid crystal compounds disclosed in the prior art: (1) significantly improved liquid crystal phase transition temperature characteristics, such as wide nematic phase liquid crystal temperature range, low melting point, and high bright spot characteristics; (2) better low-temperature compatibility; (3) low rotational viscosity; (4) low dielectric loss characteristics and large dielectric anisotropy at high frequencies; (5) high birefringence. The above advantages are very beneficial for microwave antennas, liquid crystal optical devices, etc.

[0022] The present invention further discloses a method for synthesizing a 2,5-difluorobenzyne-containing liquid crystal compound, the method comprising: (1) reacting 2,5-difluoroaniline with a halogenating agent to obtain 4-halogen-substituted-2,5-difluoroaniline; (2) subjecting 4-halogen-substituted-2,5-difluoroaniline to a coupling reaction with an aromatic boronic acid derivative or a derivative containing a terminal alkynyl group under transition metal catalysis to obtain a benzidine intermediate or an alkynyl aniline intermediate; (3) converting the benzidine intermediate or the alkynyl aniline intermediate into a corresponding iodide intermediate through a diazotization reaction; and (4) subjecting the iodide intermediate to a tandem reaction with trimethylsilyl prop(butyl or pent)yne and tetrabutylammonium fluoride under the action of a transition metal catalyst to obtain a 2,5-difluorobenzyne-containing liquid crystal compound.

[0023] An optional scheme is that the halogenating agent in the above step (1) includes iodine, bromine, or N-bromosuccinimide.

[0024] An optional scheme is that the transition metal catalyst described in the above step (2) is a catalyst containing metal palladium and nickel. More preferably, it is a complex containing metal palladium and nickel. Among them, the metal palladium catalyst is more preferably tetrakistriphenylphosphine palladium and ditriphenylphosphine palladium chloride.

[0025] The present invention also provides a liquid crystal composition, which comprises one or more liquid crystal compounds selected from the general structural formula I, and the mass percentage of the one or more liquid crystal compounds selected from the general structural formula I is 1% to 100%. In some preferred embodiments, the liquid crystal composition comprises one or more liquid crystal compounds selected from the general structural formula I-1, and the mass percentage is 10% to 100%.

[0026] In a further embodiment, the liquid crystal composition of the present invention further comprises one or more liquid crystal compounds selected from the group consisting of the general structural formula II as the second component, with a mass percentage of 0 to 95%.

[0027]

[0028] Wherein R3 and R4 are independently alkyl or alkoxy with 1 to 10 carbon atoms, alkenyl or alkenyloxy with 2 to 10 carbon atoms, fluorine, chlorine, cyano (-C≡N), isothiocyanate (-N=C=S), trifluoromethyl (-CF3), trifluoromethoxy (-OCF3); Z3 and Z4 are independently single bond, -C≡C-, -CH=CH-, -CF=CF-, -CF2O- or -CH2CH2; Ring C, Ring D and Ring E are independently benzene ring, cyclohexane or cyclohexene, wherein hydrogen on the benzene ring may be substituted by fluorine, chlorine, methyl or ethyl; m=0, 1 or 2. In a preferred embodiment, the liquid crystal composition of the present invention contains one or more liquid crystal compounds selected from the group consisting of the general structural formulae Ⅱ-1 to Ⅱ-8.

[0029]

[0030] In formulae II-1 to II-8: R5 and R6 are independently alkyl groups having 1 to 7 carbon atoms or alkoxy groups having 1 to 7 carbon atoms; R7 is fluorine, chlorine, methyl or ethyl; ring C is a benzene ring or cyclohexane; m = 0, 1 or 2.

[0031] The liquid crystal composition of the present invention preferably contains 1% to 100% by mass, preferably 10% to 90% by mass, more preferably 15% to 80% by mass of the compound of formula I. It also contains 0% to 90% by mass, preferably 5% to 80% by mass, and particularly preferably 10% to 70% by mass of the compound of formula II.

[0032] In a further embodiment, the liquid crystal composition of the present invention may further comprise 0.001-1% of an additive, wherein the additive is a hindered phenol antioxidant and / or a hindered amine light stabilizer, etc. The hindered phenol antioxidant is preferably selected from the following structures:

[0033]

[0034] Here, R is an alkyl group having 1 to 9 carbon atoms or an alkoxy group having 1 to 9 carbon atoms.

[0035] The hindered amine light stabilizer is preferably selected from the following structures:

[0036]

[0037] The preferred amount of the additive added to the liquid crystal composition is 0.01% to 0.5%, more preferably 0.02% to 0.2%.

[0038] In some further embodiments, the liquid crystal composition of the present invention may further comprise one or more chiral additives, the mass percentage of which is 0.01% to 1%; preferably 0.1% to 0.5%. The chiral additives are preferably selected from the following structures:

[0039]

[0040] Here, R is an alkyl group having 1 to 9 carbon atoms or an alkoxy group having 1 to 9 carbon atoms.

[0041] In a further preferred embodiment, 3 to 20 compounds of formula I or formula II are preferably present, and 5 to 18 and 7 to 15 compounds are more preferably present. These compounds can be mixed in a conventional manner: various compounds are weighed according to a predetermined mass ratio, and then heated and mixed homogeneously by stirring with magnetic stirring or ultrasonic stirring until each component is completely dissolved; and then filtered to obtain. Liquid crystal compositions can also be prepared in other conventional ways, such as using so-called premixes, or using so-called "multi-bottle" systems, in which the components themselves are ready-to-use mixtures.

[0042] The preferred liquid crystal composition of the present invention has a tuning rate τ≥0.24, more preferably ≥0.26; the preferred liquid crystal material has a vertical dielectric loss tanδ ⊥ ≤0.012, more preferably tanδ ⊥ ≤0.010; material quality factor η≥20, preferably η≥30. The preferred nematic phase temperature range of the liquid crystal composition of the present invention is 0 to 50°C or above (0 to 50°C or above refers to a temperature range expanded on the basis of 0 to 50°C, such as -5 to 55°C, -8 to 60°C, etc.), and the more preferred nematic phase temperature range is -10 to 70°C or above; the preferred rotational viscosity γ1 of the liquid crystal composition is ≤600mPa·s, more preferably ≤500mPa·s.

[0043] The liquid crystal composition of the present invention has a relatively high birefringence (Δn). The preferred liquid crystal composition of the present invention has a Δn≥0.30 at 25° C. and 589 nm, and more preferably Δn≥0.35.

[0044] The liquid crystal composition according to the present invention is suitable for manufacturing liquid crystal optical elements or optical devices, including phase modulation devices, gratings, wavelength selective switches (WSS), etc., due to its characteristics such as large birefringence and low viscosity.

[0045] The liquid crystal composition of the present invention is also suitable for preparing optical microwave components, such as phase shifters that can be tuned by applying 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.

[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 wide nematic liquid crystal phase, high birefringence, low viscosity, good low-temperature compatibility, etc. The composition based on the liquid crystal compound of the present invention obtains a large dielectric tuning rate, extremely low dielectric loss, low rotational viscosity, and a large elastic constant at high frequencies; and has the advantages of a large birefringence, a wide operating temperature range, etc. 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. It should be noted that the following embodiments are some preferred examples of the present invention, and equivalent selections or substitutions made by those skilled in the art based on the disclosure herein are within the protection scope of the present invention.

[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 of the molecular long axis (ε ∥ ) and the dielectric constant along the molecular short axis (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 properties of liquid crystals at high frequencies, including dielectric constant and dielectric loss (Δε, tanδ, 19 GHz): The test method reported in the literature was adopted: Penirschke, A. (2004). Cavity perturbation method for characterization of liquid crystals up to 35 GHz. Microwave Conference, 2004.34thEuropean .

[0058] Under a constant temperature of 25°C, liquid crystal is poured into a polytetrafluoroethylene (PTFE) or fused silica capillary, and the capillary filled with liquid crystal is inserted into the middle of a resonant chamber with a resonant frequency of 19 GHz. Then an input signal source is applied, and a vector network analyzer is used to record the output signal results. The changes in the resonant 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 (ε) perpendicular and parallel to the liquid crystal director are ∥ , ε ⊥ , tanδ ∥ , tanδ ⊥ ) is obtained by orienting the liquid crystal in a magnetic field, setting the direction of the magnetic field accordingly and then rotating it by 90° accordingly.

[0059] Dielectric anisotropy value Δε=ε ∥ -ε ⊥ .

[0060] Tuning rate τ = Δε / ε ∥ .

[0061] Material quality factor η = τ / tanδ ⊥ .

[0062] The basic formula HOST used to evaluate the performance of monomer liquid crystals is obtained by mixing the following three monomer liquid crystals in a mass ratio of 1:1:1:

[0063]

[0064] The relevant descriptions of the codes involved in this article are shown in Tables 1-3.

[0065] Table 1 Physical parameters

[0066]

[0067]

[0068] Liquid crystal phase transition temperature: C represents melting point, S represents smectic phase, N represents nematic phase, and I represents liquid state.

[0069] Table 2 Structural abbreviations

[0070]

[0071] Table 3 Examples of abbreviations

[0072]

[0073]

[0074] Embodiment 1:

[0075] This example is the synthesis of 1-((4-n-pentylphenyl)ethynyl)-2,5-difluoro-4-(1-propynyl)benzene, and the structural formula is as follows:

[0076]

[0077] Its synthetic route is as follows:

[0078]

[0079] The specific method is as follows:

[0080] (1) 12.9 g of 2,5-difluoroaniline, 100 mL of dichloromethane, and 8.4 g of sodium bicarbonate were added to a reaction container, stirred at room temperature, 25.4 g of iodine was added in batches, stirred and reacted overnight, the organic layer was separated, washed with aqueous sodium bisulfite, and then washed with water until neutral; the solvent was removed by concentration, and the obtained product was recrystallized with petroleum ether to obtain 19 g of 2,5-difluoro-4-iodoaniline;

[0081] (2) Under nitrogen protection, 12.8 g of 2,5-difluoro-4-iodoaniline, 100 mL of triethylamine, 0.35 g of ditriphenylphosphine palladium chloride, 0.29 g of cuprous iodide, and 0.39 g of triphenylphosphine were added to the reactor, the temperature was raised to 50° C., 30 mL of triethylamine solution containing 8.6 g of 4-n-pentylphenylacetylene was added dropwise, and the mixture was kept warm for 4 h after the addition was completed. The mixture was cooled to room temperature, filtered, and the filtrate was concentrated to dryness. 100 mL of toluene was added, the mixture was washed with water, dried, toluene was removed under reduced pressure, and petroleum ether was added for recrystallization to obtain 12.6 g of brown solid 2,5-difluoro-4-((4-n-pentylphenyl)ethynyl)aniline;

[0082] (3) Add 12.6 g of the solid obtained in the previous step and 100 mL of tetrahydrofuran to a reaction vessel and stir to dissolve. Add 30 mL of 35% hydrochloric acid, cool to -5 to -10°C, drop 30 mL of an aqueous solution containing 5.8 g of sodium nitrite, stir for 30 min after the drop is complete, drop 60 mL of an aqueous solution containing 14 g of potassium iodide, stir for 2 h, warm to room temperature, and add 100 mL of toluene for extraction. Wash the organic layer with water until it is neutral, remove the solvent under reduced pressure, and obtain 12.4 g of 1,4-difluoro-2-iodo-5-((4-n-pentylphenyl)ethynyl)benzene.

[0083] (4) Under nitrogen protection, add 12.4 g of 1,4-difluoro-2-iodo-5-((4-n-pentylphenyl)ethynyl)benzene, 120 mL of triethylamine, 0.30 g of ditriphenylphosphine palladium chloride, 0.27 g of cuprous iodide, 0.35 g of triphenylphosphine, and 4.7 g of trimethylsilyl propyne to the reactor, raise the temperature to 40°C, slowly drop 50 mL of a 1 mol / L tetrabutylammonium fluoride (TBAF) tetrahydrofuran solution, and keep the temperature for 4 h after the drop is complete. Cool to room temperature, filter, concentrate the filtrate to dryness, add 100 mL of toluene, wash with water, dry, and remove toluene under reduced pressure. The product is dissolved in n-heptane, passed through a silica gel column, and eluted with n-heptane. The eluate is concentrated to dryness under reduced pressure, and recrystallized from n-heptane to obtain 6.2 g of 1-((4-n-pentylphenyl)ethynyl)-2,5-difluoro-4-(1-propynyl)benzene as a white solid.

[0084] The product structure identification data are as follows:

[0085] 1H NMR (500MHz, CDCl3) δ (ppm): 0.889 (t, 3H, J = 7.5Hz), 1.285 ~ 1.361 (m, 4H), 1.581 ~ 1.641 (m, 2H), 2.105 (s, 3 H), 2.611 (t, 3H, J = 7.5Hz), 7.080 (dd, 1H, J1 = 9.5Hz, J2 = 5.5Hz), 7.138 ~ 7.174 (m, 3H), 7.447 (d, 2H, J = 8Hz).

[0086] 13 C NMR (125MHz, CDCl3) δ (ppm): 4.7, 14, 0, 22.5, 30.9, 31.4, 35.9, 72.4, 81.1, 94.2, 96.8,112.7,113.6,119.1,119.4,119.5,128.6(2C),131.7(2C),144.4,158.1(J C-F =245Hz),158.4(J C-F =245Hz).

[0087] MS m / z(RI,%):322.2(M + ,73),265.1(100).

[0088] DSC: C 53.9N(52.5)I.

[0089] According to DSC test data, the liquid crystal compound is a single-phase liquid crystal, and a nematic phase appears when the temperature is lowered to 52.5°C.

[0090] The compound was added to the basic formula HOST at a ratio of 15% and stored at -10°C for 10 days without crystallization.

[0091] Further testing revealed the following physical property parameters of the compound: Δn=0.36, Δε=0.9, γ1=113 mPa·s.

[0092] Embodiment 2:

[0093] This embodiment is 1-((4-n-propylphenyl)ethynyl)-2,5-difluoro-4-(1-propynyl)benzene, and the structural formula is as follows:

[0094]

[0095] 4-n-propylphenylacetylene was used to replace the 4-n-pentylphenylacetylene in Example 1, and other operations were performed using the same synthesis method as Example 1 to obtain 1-((4-n-propylphenyl)ethynyl)-2,5-difluoro-4-(1-propynyl)benzene.

[0096] The structural identification data are as follows:

[0097] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.936 (t, 3H, J = 7.5Hz), 1.604 ~ 1.679 (m, 2H), 2.105 (s, 3H), 2.597 ( t,3H,J=7.5Hz),7.081(dd,1H,J1=9.5Hz,J2=5.5Hz),7.139~7.172(m,3H),7.449(d,2H,J=8Hz).

[0098] 13 C NMR (125MHz, CDCl3) δ (ppm): 4.7, 13, 7, 24.3, 38.0, 72.4, 81.1, 94.2, 96.8, 112.7,113.6,119.3,119.5,119.6,128.6(2C),131.7(2C),144.1,158.1(J C-F =245Hz),158.4(J C-F =245Hz).

[0099] MS m / z(RI,%):294.1(M + ,67),265.1(100).

[0100] DSC: C 64.9 (N 54.0)I.

[0101] According to DSC test data, the liquid crystal compound is a single-phase liquid crystal, and a nematic phase appears when the temperature is lowered to 54.0°C.

[0102] The compound was added to the basic formula HOST at a ratio of 15% and stored at -10°C for 10 days without crystallization.

[0103] Further testing revealed the following physical property parameters of the compound: Δn=0.38, Δε=0.9, γ1=95 mPa·s.

[0104] Embodiment 3:

[0105] This embodiment is 1-((4-n-butylphenyl)ethynyl)-2,5-difluoro-4-(1-propynyl)benzene, and the structural formula is as follows:

[0106]

[0107] 4-n-butylphenylacetylene was used to replace the 4-n-pentylphenylacetylene in Example 1, and other operations were performed using the same synthesis method as Example 1 to obtain 1-((4-n-butylphenyl)ethynyl)-2,5-difluoro-4-(1-propynyl)benzene.

[0108] The structural identification data are as follows:

[0109] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.926 (t, 3H, J = 7.5Hz), 1.313 ~ 1.387 (m, 2H), 1.565 ~ 1.621 (m, 2H), 2.107 (s, 3 H), 2.621 (t, 3H, J = 7.5Hz), 7.082 (dd, 1H, J1 = 9.5Hz, J2 = 5.5Hz), 7.139 ~ 7.176 (m, 3H), 7.449 (d, 2H, J = 8Hz).

[0110] 13 C NMR (125MHz, CDCl3) δ (ppm): 4.7,13,9,22.3,33.4,35.7,72.4,81.1,94.2,96 .8,112.7,113.6,119.1,119.4,119.5,128.6(2C),131.7(2C),144.3,158.1(J C-F =245Hz),158.4(J C-F =245Hz).

[0111] MS m / z (RI, %): 308.2 (M + ,70),265.1(100).

[0112] DSC: C 52.9 (N 28.0)I.

[0113] According to DSC test data, the liquid crystal compound is a single-phase liquid crystal, and a nematic phase appears when the temperature is lowered to 28.0°C.

[0114] The compound was added to the basic formula HOST at a ratio of 15% and stored at -10°C for 10 days without crystallization.

[0115] Further testing yielded the following physical property parameters for the compound: Δn=0.37, Δε=0.9, γ1=108 mPa·s.

[0116] Embodiment 4:

[0117] This embodiment is 1-((4-(but-3-enyl)phenyl)ethynyl)-2,5-difluoro-4-(1-propynyl)benzene, and the structural formula is as follows:

[0118]

[0119] 4-(But-3-enyl)phenylacetylene was used to replace the 4-n-pentylphenylacetylene in Example 1, and the other operations were performed using the same synthesis method as Example 1 to obtain 1-((4-(but-3-enyl)phenyl)ethynyl)-2,5-difluoro-4-(1-propynyl)benzene.

[0120] The structural identification data are as follows:

[0121] 1 H NMR (500MHz, CDCl3) δ (ppm): 2.105 (s, 3H), 2.348 ~ 3.392 (m, 2H), 2.723 (t, 3H, J = 7.5Hz), 4.972 ~ 5.050 (m, 2H),5.790~5.871(m,1H),7.078(dd,1H,J1=9.5Hz,J2=5.5Hz),7.138~7.184(m,3H),7.455(d,2H,J=8Hz).

[0122] 13 C NMR (125MHz, CDCl3) δ (ppm): 4.7, 35.2, 35.3, 72.4, 81.2, 94.3, 96.8, 112.6, 113.7, 119.1, 119.5, 119.7, 128.6 (2C), 131.8 (2C), 143.2, 158.1 (J C-F =245Hz),158.4(J C-F =245Hz).

[0123] MS m / z (RI, %): 306.2 (M + ,73),265.1(100).

[0124] DSC: C 76.0 (N 51.3)I.

[0125] According to DSC test data, the liquid crystal compound is a single-phase liquid crystal, and a nematic phase appears when the temperature is lowered to 51.3°C.

[0126] The compound was added to the basic formula HOST at a ratio of 15%, and further testing revealed the following physical property parameters of the compound: Δn = 0.38, Δε = 0.7, γ1 = 106 mPa·s.

[0127] Embodiment 5:

[0128] This embodiment is 1-(4-n-pentyloxyphenyl)ethynyl-2,5-difluoro-4-(1-propynyl)benzene, and the structural formula is as follows:

[0129]

[0130] 4-n-pentyloxyphenylacetylene was used to replace the 4-n-pentylphenylacetylene in Example 1, and other operations were performed using the same synthesis method as Example 1 to obtain 1-((4-(n-pentyloxy)phenyl)ethynyl)-2,5-difluoro-4-(1-propynyl)benzene.

[0131] The structural identification data are as follows:

[0132] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.934 (t, 3H, J = 7.5Hz), 1.346 ~ 1.490 (m, 4H), 1.762 ~ 1.818 (m, 2H), 2.105 (s, 3H), 3.965 (t, 3H, J = 6.5Hz), 6.870 (d, 2H, J = 8Hz), 7.074 (dd, 1H, J1 = 9.5Hz, J2 = 5.5Hz), 7.139 (dd, 1H, J1 = 9.5Hz, J2 = 5.5Hz), 7.449 (d, 2H, J = 8Hz).

[0133] 13 C NMR (125MHz, CDCl3) δ (ppm): 4.7, 14.0, 22.5, 28.2, 28.9, 68.1, 72.4, 80.4, 94 .1,96.8,112.9,113.3,114.1,114.6(2C),119.0,119.5,133.3(2C),158.0(J C-F =245Hz),158.4(J C-F =245Hz),159.9.

[0134] MS m / z(RI,%):338.2(M + ,78),268.1(100).

[0135] DSC: C 68.4N 88.2I.

[0136] The compound was added to the basic formula HOST at a ratio of 15%, and further testing yielded the following physical property parameters of the compound: Δn=0.39, Δε=1.8, γ1=186 mPa·s.

[0137] Embodiment 6:

[0138] This example is the synthesis of 1-(4-(trans-4-n-propylcyclohexyl)phenyl)ethynyl-2,5-difluoro-4-(1-propynyl)benzene, and the structural formula is as follows:

[0139]

[0140] 4-(trans-4-n-propylcyclohexyl)phenylacetylene was used to replace the 4-n-pentylphenylacetylene in Example 1, and other operations were performed using the same synthesis method as Example 1 to obtain 1-(4-(trans-4-n-propylcyclohexyl)phenyl)ethynyl-2,5-difluoro-4-(1-propynyl)benzene.

[0141] The structural identification data are as follows: 1 H NMR (500MHz, CDCl3) δ (ppm): 0.900 (t, 3H, J = 7.5Hz), 1.000 ~ 1.083 (m, 2H), 1.186 ~ 1.475 (m, 7H), 1.853 ~ 1.889 (m, 4H), 2.105 (s, 3H), 2.470(m,1H),7.082(dd,1H,J1=9.5Hz,J2=5.5Hz),7.150(dd,1H,J1=9.5Hz,J2=5.5Hz),7.193(d,2H,J=8Hz),7.449(d,2H,J=8Hz).

[0142] 13 C NMR (125MHz, CDCl3) δ (ppm): 4.7, 14.4, 20.0, 33.5 (2C), 34.1 (2C), 37.0, 39.7, 44.7, 72.4, 8 1.0,94.2,96.8,112.7,113.5,119.1,119.5,119.6,127.0(2C),131.8(2C),149.2,158.1(J C-F =245Hz),158.4(J C-F =245Hz).

[0143] MS m / z(RI,%):376.2(M + ,100),278.1(27).

[0144] DSC: C96.4 N 240.0I.

[0145] According to DSC test data, the nematic phase temperature of the liquid crystal compound reaches 143.6°C.

[0146] The compound was added to the basic formula HOST at a ratio of 15% and stored at -10°C for 10 days without crystallization.

[0147] Further testing yielded the following physical property parameters for the compound: Δn=0.37, Δε=1.8, γ1=546 mPa·s.

[0148] Embodiment 7:

[0149] This example is the synthesis of 4-((2,5-difluoro-4-(1-propynyl)phenyl)ethynyl)-4'-n-pentyl-1,1'-biphenyl, the structural formula is as follows:

[0150]

[0151] 4-((2,5-difluoro-4-(1-propynyl)phenyl)ethynyl)-4'-n-pentyl-1,1'-biphenyl was obtained by replacing 4-n-pentylphenylacetylene in Example 1 with 4'-n-pentyl-4-ethynylbiphenyl and adopting the same synthesis method as Example 1 for other operations.

[0152] The structural identification data are as follows:

[0153] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.904 (t, 3H, J = 7Hz), 1.330 ~ 1.376 (m, 4H), 1.618 ~ 1.678 (m, 2H), 2.108 (s, 3H), 2.641 (t, 2H, J = 7.5Hz), 7.094(dd,1H,J1=9.5Hz,J2=5.5Hz),7.178(dd,1H,J1=9.5Hz,J2=5.5Hz),7.257(d,2H,J=8Hz),7.515(d,2H,J=8Hz),7.583(s,4H).

[0154] 13 C NMR (125MHz, CDCl3) δ (ppm): 4.7, 14, 5, 22.6, 31.2, 31.6, 35.6, 72.4, 82.2, 94.4, 96.6, 112.5, 113.8,119.1,119.6,120.8,126.9(4C),129.0(2C),132.2(2C),137.5,141.7,142.8,158.1(J C-F =245Hz),158.4(J C-F =245Hz).

[0155] MS m / z(RI,%):398.2(M + ,86),341.1(100).

[0156] DSC: C96.2 S152.3 N 232.4I.

[0157] The compound was added to the basic formula HOST at a ratio of 15%, and further testing revealed the following physical property parameters of the compound: Δn = 0.48, Δε = 2.7, and γ1 = 518 mPa·s.

[0158] Embodiment 8:

[0159] This example is the synthesis of 4'-n-butyl-4-((2,5-difluoro-4-(1-propynyl)phenyl)ethynyl)-3-fluoro-1,1'-biphenyl, the structural formula is as follows:

[0160]

[0161] 4'-n-butyl-3-fluoro-4-ethynylbiphenyl was used to replace the 4-n-pentylphenylacetylene in Example 1, and other operations were performed using the same synthesis method as Example 1 to obtain 4'-n-butyl-4-((2,5-difluoro-4-(1-propynyl)phenyl)ethynyl)-3-fluoro-1,1'-biphenyl.

[0162] The structural identification data are as follows:

[0163] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.943 (t, 3H, J = 7.5Hz), 1.344 ~ 1.418 (m, 2H), 1.599 ~ 1.645 (m, 2H), 2.112 (s, 3H), 2.653 (t, 2H, J = 7.5Hz), 7.103 (dd,1H,J1=9.5Hz,J2=5.5Hz),7.204(dd,1H,J1=9.5Hz,J2=5.5Hz),7.264(d,2H,J=8Hz),7.325(m,2H),7.497(m,2H),7.549(d,1H,J=8Hz).

[0164] 13 C NMR (125MHz, CDCl3) δ (ppm): 4.7, 14, 0, 22.4, 33.6, 35.3, 72.3, 87.0, 89.9, 94.6, 109.3, 112.2, 113.8,114.2,119.2,119.6,122.4,126.8(2C),129.1(2C),133.7,136.3,143.5,144.2,158.1(J C-F =245Hz),158.4(J C-F =245Hz),163.0(J C-F =250Hz).

[0165] MS m / z(RI,%):402.2(M+ ,88),359.1(100).

[0166] DSC: C 68.4N 228.9I.

[0167] The compound was added to the basic formula HOST at a ratio of 15% and stored at -10°C for 10 days without crystallization.

[0168] Further testing yielded the following physical property parameters for the compound: Δn=0.47, Δε=3.5, γ1=524 mPa·s.

[0169] Embodiment 9:

[0170] The components and mass percentages of the liquid crystal composition of this embodiment and their performance parameters are shown in Table 4 below:

[0171] Table 4

[0172]

[0173] The results in Table 4 show that the liquid crystal composition of this embodiment has lower dielectric loss and larger quality factor at a high frequency of 19 GHz, as well as higher birefringence.

[0174] Embodiment 10:

[0175] The components and mass percentages of the liquid crystal composition of this embodiment and their performance parameters are shown in Table 5:

[0176] Table 5

[0177]

[0178] The test data in Table 5 show that the liquid crystal composition of this embodiment has lower dielectric loss and larger quality factor at a high frequency of 19 GHz, as well as higher birefringence.

[0179] Embodiment 11:

[0180] The components and mass percentages of the liquid crystal composition of this embodiment and their performance parameters are shown in Table 6:

[0181] Table 6

[0182]

[0183]

[0184] The performance data in Table 6 show that the liquid crystal composition of this embodiment has lower dielectric loss and larger quality factor at a high frequency of 19 GHz, as well as higher birefringence and lower rotational viscosity.

[0185] Embodiment 12:

[0186] The components and mass percentages of the liquid crystal composition of this embodiment and their performance parameters are shown in Table 7:

[0187] Table 7

[0188]

[0189] The performance data in Table 7 show that the liquid crystal composition of this embodiment has a higher birefringence, a lower rotational viscosity, and a larger dielectric anisotropy at low frequency, and is suitable for use in optical elements such as gratings, wavelength selective switches, etc.

[0190] Comparative Example 1:

[0191] Patent EP0377516A2 discloses a liquid crystal compound having a propynyl group at the molecular end, and the structural formula is as follows:

[0192]

[0193] In Example 3 of the present invention, the melting point of the compound after the introduction of two fluorine atoms is 28.1° C. lower than that of compound (a).

[0194] Compared with compound (b), Example 6 of the present invention not only has a melting point reduced by 22.5° C., but also exhibits only a nematic phase without a smectic phase; the temperature range of the nematic phase is increased by 25.9° C. compared with compound (b).

[0195] Comparative Example 2:

[0196] Patent CN105473686A discloses a fluorine-substituted benzyne compound, the structural formula of which is as follows:

[0197]

[0198] The compound (c) has a fluorine atom as a substituent, has no liquid crystal phase, and has a high melting point.

[0199] Compared with the compound (c) of comparative example 2, the melting point of Example 3 of the present invention is not only reduced by 34.1° C., but also the compound has a nematic liquid crystal phase when the temperature is lowered.

[0200] Comparative Example 3:

[0201] The compounds (a), (b), (c) in Comparative Examples 1 and 2, and the compounds in Examples 3 and 6 of the present invention were dissolved in the basic formula HSOT at a mass ratio of 15%, and low-temperature storage experiments were carried out at 5°C and -10°C, respectively. The results are shown in Table 8 below.

[0202] Table 8

[0203]

[0204]

[0205] It can be seen that the liquid crystal compound of the present invention has very excellent low-temperature compatibility compared with the compounds of Comparative Examples 1 and 2.

Claims

1. A 2,5-difluorobenzyne-containing liquid crystal compound, characterized in that: The structure of the compound is shown in Formula I: in: R1 is an alkyl or alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, or an alkyl group substituted with a cycloalkyl group having 3 to 8 carbon atoms, and the hydrogen on the carbon atom of R1 may be substituted with fluorine; R2 is an alkyl group having 1 to 3 carbon atoms; Z1 is a single bond, -C≡C-, -CH=CH-, -CF=CF-, -CF2O- or -CH2CH2; Z2 is a single bond, -C≡C-, -CH=CH-, -CF=CF-, -CF2O- or -CH2CH2; Ring A is a benzene ring, cyclohexane or cyclohexene, wherein the hydrogen on the benzene ring may be substituted by fluorine, chlorine, methyl or / and ethyl; n=0, 1 or 2; Ring B is a benzene ring, cyclohexane or cyclohexene, wherein the hydrogen on the benzene ring may be substituted by fluorine, chlorine, methyl or / and ethyl.

2. The liquid crystal compound according to claim 1, characterized in that n＝0。 3. The liquid crystal compound according to claim 1, characterized in that n=1, ring A is a benzene ring or cyclohexane.

4. The liquid crystal compound according to claim 1, characterized in that n=2, and ring A is a benzene ring or cyclohexane.

5. The liquid crystal compound according to claim 1, characterized in that The structural formula of the compound is any one of the structural formulas Ⅰ-1 to Ⅰ-11; In compounds Ⅰ-1 to Ⅰ-11, R is independently an alkyl or alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, or an alkyl group substituted with a cycloalkyl group having 3 to 8 carbon atoms, and the hydrogen on the carbon atom of R may be substituted with fluorine.

6. A liquid crystal composition, characterized in that: The liquid crystal composition comprises one or more liquid crystal compounds selected from the group consisting of liquid crystal compounds represented by structural formula I, and the mass percentage of the compound represented by formula I is 1% to 100%.

7. The liquid crystal composition according to claim 6, characterized in that: The liquid crystal composition further comprises a liquid crystal compound represented by structural formula II, and the mass percentage of the compound of formula II is 0-95%; in: R3 and R4 are independently alkyl having 1 to 10 carbon atoms, alkoxy having 1 to 10 carbon atoms, alkenyl having 2 to 10 carbon atoms, alkenyloxy having 2 to 10 carbon atoms, fluorine, chlorine, cyano, isothiocyanate, trifluoromethyl or trifluoromethoxy; Z3 and Z4 are independently a single bond, -C≡C-, -CH=CH-, -CF=CF-, -CF2O- or -CH2CH2; Ring C, Ring D and Ring E are independently benzene rings, cyclohexane or cyclohexene, wherein hydrogen on the benzene ring may be substituted by fluorine, chlorine, methyl or ethyl; m=0, 1 or 2.

8. The liquid crystal composition according to claim 6 or 7, characterized in that: The liquid crystal composition further comprises 0.001% to 1% by mass of an additive, wherein the additive is selected from a hindered phenol antioxidant and / or a hindered amine light stabilizer.

9. The liquid crystal composition according to claim 6 or 7, characterized in that: The liquid crystal composition further comprises one or more chiral additives, and the mass percentage content of the one or more chiral additives is 0.01% to 1%.

10. The liquid crystal composition according to claim 6 or 7, characterized in that: The tuning rate of the liquid crystal composition τ≥0.24; the dielectric loss tanδ in the vertical direction ⊥ ≤0.012; material quality factor η≥20.

11. The liquid crystal composition according to claim 6 or 7, characterized in that: The nematic phase temperature range of the liquid crystal composition is 0 to 50° C. and above; the rotational viscosity γ1 is ≤600 mPa·s.

12. The liquid crystal composition according to claim 6 or 7, characterized in that: The birefringence Δn of the liquid crystal composition at 25° C. and 589 nm is ≥ 0.

30.

13. A liquid crystal high frequency component, characterized in that: The liquid crystal high-frequency component comprises the liquid crystal compound according to any one of claims 1 to 5 or the liquid crystal composition according to claim 6 or 7.

14. A liquid crystal optical element, characterized in that: The liquid crystal optical element comprises the liquid crystal compound according to any one of claims 1 to 5 or the liquid crystal composition according to claim 6 or 7.

15. The method for synthesizing the 2,5-difluorobenzyne-containing liquid crystal compound according to claim 1, characterized in that: include: (1) 2,5-difluoroaniline reacts with a halogenating agent to obtain 4-halogen-substituted-2,5-difluoroaniline; (2) 4-halogen-substituted-2,5-difluoroaniline undergoes a coupling reaction with an aryl boronic acid derivative or a derivative containing a terminal alkynyl group under transition metal catalysis to obtain a benzidine intermediate or an alkynyl aniline intermediate; (3) converting the benzidine intermediate or alkynylaniline intermediate into the corresponding iodide intermediate through a diazotization reaction; (4) The iodide intermediate reacts with trimethylsilyl propyne and tetrabutyl ammonium fluoride in the presence of a transition metal catalyst to obtain a liquid crystal compound containing 2,5-difluorobenzyne.

16. The synthesis method according to claim 15, characterized in that In step (1), the halogenating agent is selected from iodine, bromine or N-bromosuccinimide.

17. The synthesis method according to claim 15, characterized in that: The transition metal catalyst is selected from a complex containing palladium or nickel.

Images