Liquid crystal isothiocyanate compounds containing 2,5-difluoro-substituted benzene and synthesis method

Abstract

This invention discloses an isothiocyanate liquid crystal compound containing 2,5-difluorosubstituted benzene and its synthesis method. The general structural formula of the disclosed compound is shown in Figure I, wherein R is an alkyl or alkoxy group with 1-10 carbon atoms, an alkenyl or alkenoxy group with 2-10 carbon atoms, a cycloalkyl group with 3-8 carbon atoms, or an alkyl group substituted with a cycloalkyl group, wherein the hydrogen atom on the carbon atom can be substituted with fluorine; Z1 and Z2 are single bonds, -C≡C-, -CH=CH-, -CF=CF-, -CH2CH2; ring A and ring B are benzene rings or cyclohexane, cyclohexene, wherein the hydrogen atom on the benzene ring can be substituted with fluorine, chlorine, methyl, or ethyl; n = 0, 1, 2. The liquid crystal compound of this invention has the advantages of a wide nematic phase temperature range, low viscosity, and high birefringence.

Description

Technical Field

[0001] This invention belongs to the field of liquid crystal material technology, specifically relating to a liquid crystal compound containing 2,5-difluorophenyl isothiocyanate and its synthesis method. Background Technology

[0002] Liquid crystal materials are widely used in optoelectronic display devices, such as various LCD TVs, desktop LCD monitors, and mobile display terminals. In recent years, with the continuous development of microwave and terahertz communication, optical communication, and laser phased array technologies, there has been an urgent demand for liquid crystal materials with high birefringence. The higher the birefringence (Δn) of a liquid crystal, the greater its dielectric anisotropy in the microwave (1-100GHz) band. Furthermore, in liquid crystal devices such as optical communication and laser phased arrays, using liquid crystals with high birefringence (Δn) can significantly shorten the response time while maintaining the optical phase modulation.

[0003] To improve the birefringence of liquid crystal materials, long conjugated chains are required in the liquid crystal molecules. For example, the molecular backbone can employ long conjugated structures of biphenyl, terphenyl, tetraphenyl, or diphenylacetylene, with cyano (-CN) or isothiocyanate (-NCS) groups at the molecular ends. Liquid crystal molecules containing isothiocyanate (-NCS) groups, in particular, exhibit higher birefringence, lower viscosity, and higher resistivity than molecules containing cyano (-CN) groups, making them a key focus of research, development, and application.

[0004] The high birefringence liquid crystal molecule structure containing isothiocyanate groups (-NCS) has been disclosed in the following literature:

[0005] [1] Catanescu CO, Wu ST, Chien LC. Tailoring the physical properties of some high birefringence isothiocyanato-based liquid crystals. Liq Cryst. 2004; 31:541-555.

[0006] [2] Parish A, Gauza S, Wu ST, Dziaduszek J, Dabrowski R. New fluorinatedterphenyl isothiocyanate liquid crystals. Liq Cryst. 2008; 35:79-86.

[0007] [3]Song Q,Gauza S,Xianyu H,Wu ST,Liao YM,Chang CY,Hsu C S.Highbirefringence lateral difluoro phenyl tolane liquid crystals.Liq Cryst.2010;37:139–147.

[0008] [4] R,Kula P,Herman J.High birefringence liquidcrystals.Crystals.2013;3(3):443-482.

[0009] Although a large number of high birefringence liquid crystals containing isothiocyanate groups (-NCS) have been disclosed, the following problems still exist:

[0010] (1) The birefringence needs to be further improved;

[0011] (2) Liquid crystals have poor low-temperature compatibility;

[0012] (3) In the microwave band, the dielectric loss of liquid crystal is relatively large;

[0013] (4) Insufficient liquid crystal phase transition characteristics, especially in the phase temperature range of nematic liquid crystals;

[0014] (5) Liquid crystals have high viscosity.

[0015] To further meet the performance requirements of optical, microwave and other components, there is an urgent need to research and develop new molecular structures with higher birefringence, wider nematic phase temperature range, lower viscosity and better overall performance. Summary of the Invention

[0016] In order to overcome the defects or deficiencies in the prior art, the present invention provides a novel fluorophenyl isothiocyanate liquid crystal compound and its synthesis method.

[0017] To achieve the above objectives, the compound structure provided by this invention is shown in general formula I:

[0018]

[0019] in:

[0020] R is an alkyl group having 1 to 10 carbon atoms, an alkyl group with hydrogen fluorine substituted for hydrogen, an alkoxy group, or an alkoxy group with hydrogen fluorine substituted for hydrogen; or an alkenyl group having 2 to 10 carbon atoms, an alkenyl group with hydrogen fluorine substituted for hydrogen, an alkenoxy group, or an alkenoxy group with hydrogen fluorine substituted for hydrogen; or a cycloalkyl group having 3 to 8 carbon atoms, a cycloalkyl group with hydrogen fluorine substituted for hydrogen, an alkyl group containing cycloalkyl substituted for hydrogen, or an alkyl group containing cycloalkyl substituted for hydrogen.

[0021] Z1 is a single bond, -C≡C-, -CH=CH-, -CF=CF-, or -CH2CH2;

[0022] Z2 is a single bond, -C≡C-, -CH=CH-, -CF=CF-, or -CH2CH2;

[0023] Ring A is a benzene ring, cyclohexane, cyclohexene, or a benzene ring in which hydrogen is substituted by fluorine, chlorine, methyl, or / and ethyl; n = 0, 1, or 2;

[0024] Ring B is a benzene ring, cyclohexane, cyclohexene, or a benzene ring in which hydrogen is substituted by fluorine, chlorine, methyl, or / and ethyl.

[0025] Furthermore, n = 0.

[0026] Furthermore, n=1, and ring A is a benzene ring or cyclohexane.

[0027] Furthermore, n=2, and ring A is a benzene ring or cyclohexane.

[0028] Furthermore, the compound has the structural formula shown in any one of formulas I-1 to I-14;

[0029]

[0030]

[0031] The present invention also provides a method for synthesizing the above-mentioned compound. The provided method includes:

[0032] (1) 2,5-Difluoroaniline reacts with a halogenating agent to give 4-halogen-substituted-2,5-difluoroaniline;

[0033] (2) 4-Halogen-substituted 2,5-difluoroaniline undergoes a coupling reaction with arylboronic acid derivatives or derivatives containing terminal alkynyl groups under transition metal catalysis to obtain benzidine intermediates or alkynylaniline intermediates.

[0034] (3) Benzidine intermediates or alkynyl aniline intermediates undergo phosgenation to obtain isothiocyanate liquid crystal compounds.

[0035] Optionally, the halogenating agent in step (1) is selected from iodine, bromine or N-bromosuccinimide.

[0036] Optionally, the transition metal catalyst is selected from palladium- or nickel-containing complexes.

[0037] The liquid crystal compound described in this invention, although possessing a similar molecular skeleton to the side-fluorinated isothiocyanate liquid crystals disclosed in the prior art, achieves surprising results compared to existing or applied side-fluorinated isothiocyanate liquid crystals by introducing fluorine substituents at specific positions on the benzene ring: (1) significantly improved liquid crystal phase transition temperature characteristics, such as a wide liquid crystal phase region, low melting point, and high-brightness characteristics; (2) higher birefringence; (3) better low-temperature compatibility; (4) significantly reduced dielectric loss at high frequencies; and (5) maintains a large high-frequency dielectric anisotropy, which is highly beneficial for the operation of microwave devices. Furthermore, this type of compound also exhibits relatively low rotational viscosity. In summary, the isothiocyanate liquid crystal compound containing 2,5-difluorosubstituted benzene disclosed in this invention surpasses the understanding of traditional liquid crystal compounds in terms of comprehensive performance. It can be used to prepare optoelectronic devices and display devices. Detailed Implementation

[0038] Unless otherwise specified, the scientific and technical terms and methods used in this article are based on the understanding of those skilled in the art or implemented using existing methods.

[0039] The present invention will be further described in detail below with reference to specific embodiments.

[0040] It should be noted that the detailed testing methods for the physical and photoelectric properties involved in this invention are as follows:

[0041] (1) Liquid crystal phase transition temperature:

[0042] Differential scanning calorimetry (DSC) was used: under a nitrogen atmosphere, the heating (cooling) rate was set to 5℃ / min.

[0043] Polarizing hot stage method: The liquid crystal sample is placed in an orthogonal polarizing microscopic hot stage, and the heating rate is set to 2℃ / min. The texture image of the liquid crystal phase transition is observed in a polarizing microscope to determine the liquid crystal phase state.

[0044] (2) Birefringence (Δn): The liquid crystal monomers were added to the basic formulation HOST at a mass ratio of 15:85% and heated to mix thoroughly. Using an Abbe refractometer, under constant temperature conditions of 25℃ and a light source of 589nm, the birefringence (Δn) was measured for ordinary light. o ) and unusual light (n e The birefringence is obtained by extrapolating the refractive index of ( ).

[0045] (3) Dielectric constant (Δε, 1kHz): Liquid crystal monomers were added to the basic formulation HOST at a mass ratio of 15:85% and heated to mix thoroughly. The dielectric constant was measured using an LCR meter under constant temperature conditions of 25℃. Δε=ε ∥ -ε ⊥ That is, the dielectric constant along the long axis of the molecule (ε) ∥ ) and the dielectric constant (ε) along the short axis of the molecule ⊥ The difference between the two values ​​is extrapolated to obtain the dielectric anisotropy value Δε.

[0046] (4) Rotational viscosity (γ1): The liquid crystal monomers were added to the basic formulation HOST at a mass ratio of 15:85% and heated to mix evenly. Under constant temperature of 25℃, the transient current value Ip of the liquid crystal molecules deflecting with the electric field was measured by applying voltage to the liquid crystal test cell, and the rotational viscosity γ1 was calculated and extrapolated.

[0047] (5) Dielectric constant and dielectric loss (Δε, tanδ, 19GHz): Liquid crystal monomers were added to the basic formulation M0 at a mass ratio of 15:85% and heated to mix evenly. Under constant temperature of 25°C, the liquid crystal was filled into a polytetrafluoroethylene (PTFE) or fused silica capillary, and the liquid crystal-filled capillary was inserted into the middle of the resonant cavity. Then, an input signal source was applied, and the output signal was recorded using a vector network analyzer. The changes in the resonant frequency and Q factor between the liquid crystal-filled capillary and the blank capillary were measured, and the dielectric constant and loss tangent were calculated. The dielectric constant components perpendicular to and parallel to the liquid crystal director were obtained by the orientation of the liquid crystal in the magnetic field, the direction of the magnetic field was set accordingly, and then rotated by 90° accordingly.

[0048] The basic formula HOST is obtained by uniformly mixing the following three monomer liquid crystals in a mass ratio of 1:1:1.

[0049]

[0050] Code name and description:

[0051] (1) Physical parameters

[0052] code name illustrate unit <![CDATA[ε ⊥ ]]> Perpendicular to the director <![CDATA[ε ∥ ]]> Dielectric constant parallel to the director Δε Dielectric anisotropy <![CDATA[tanδ ⊥ ]]> Dielectric loss tangent perpendicular to the director <![CDATA[tanδ ∥ ]]> Dielectric loss tangent perpendicular to the director Δn Birefringence <![CDATA[γ1]]> rotational viscosity mPa·s η <![CDATA[Microwave quality factor; η = Δε / (ε ∥ *tanδ ⊥ )]]>

[0053] Liquid crystal phase transition temperature: C represents melting point, S represents smectic phase, N represents nematic phase, and I represents liquid state.

[0054] Example 1:

[0055] This example describes the synthesis of 2,5-difluoro-1-isothiocyanate-4-((4-n-pentyl)ethynyl)benzene, and the specific method is as follows:

[0056] (1) 12.9 g of 2,5-difluoroaniline, 100 mL of dichloromethane and 8.4 g of sodium bicarbonate were added to a reaction vessel and stirred at room temperature. 25.4 g of iodine was added in portions and stirred overnight. The organic layer was separated and washed with water-soluble sodium bisulfite and then washed with water until neutral. The solvent was removed by concentration and the product was recrystallized with petroleum ether to obtain 19 g of 2,5-difluoro-4-iodoaniline.

[0057] (2) Under nitrogen protection, 12.8 g of 2,5-difluoro-4-iodoaniline, 100 mL of triethylamine, 0.35 g of palladium chloride ditriphenylphosphine, 0.29 g of cuprous iodide, and 0.39 g of triphenylphosphine were added to the reactor. The temperature was raised to 50 °C, and 30 mL of triethylamine solution containing 8.6 g of 4-pentylphenylacetylene was added dropwise. After the addition was complete, the reaction was kept at the temperature for 4 h. 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, and the toluene was removed under reduced pressure. Petroleum ether was added and the mixture was recrystallized to obtain 12.6 g of brown solid.

[0058] (3) Add 12.6 g of the brown solid obtained in the previous step, 100 mL of chloroform, and 25 mL of water to the reaction vessel, cool down to below 5 °C, slowly add 7.2 g of sulfur phosgene, and after the addition is complete, heat up to reflux for 2 h, cool down to room temperature, separate the layers, wash the organic layer with sodium bicarbonate aqueous solution, wash with water until neutral, remove the solvent by vacuum distillation, pass the obtained product through a silica gel column, elute with n-heptane, recrystallize the product with n-heptane to obtain 10.9 g of white solid with a gas chromatographic purity of 99.9%.

[0059] The synthesis route of the above method is shown below:

[0060]

[0061] The product structure identification data are as follows:

[0062] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.887 (t, 3H, J = 7Hz), 1.265 ~ 1.339 (m, 4H), 1.575 ~ 1.635 (m, 2H), 2.604 (t, 2H, J = 7.5Hz), 6.868 (dd, 1H, J1 = 8.5Hz, J2 = 6Hz), 7.159 (d, 2H, J = 8.5Hz), 7.229 (dd, 1H, J1 = 9.5Hz, J2 = 6.5Hz), 7.429 (d, 2H, J = 8Hz).

[0063] 13C NMR (125MHz, CDCl3) δ (ppm): 14.0, 22.6, 30.9, 31.5, 36.0, 80.5, 97.5, 111.9 (dd, J1=18.5Hz, J2=8.5Hz), 113.0 (d, J=26Hz), 119.3, 119.7 (dd, J1=22Hz, J2=2.4Hz), 120.9 (dd, J1=16Hz, J2=11Hz), 128.7, 131.7, 143.6, 144.3, 154.6 (d, J=250Hz), 158.3 (d, J=250Hz).

[0064] MS m / z (RI,%): 341.1 (M + ,100),284.1(92).

[0065] DSC: C 51.5N(44.9)I.

[0066] According to DSC test data, the liquid crystal compound is a single-variable liquid crystal, and a nematic phase appears when the temperature is reduced to 44.9℃.

[0067] Example 2:

[0068] This example describes the synthesis of 2,5-difluoro-1-isothiocyanate-4-((4-(4-n-pentylcyclohexyl)phenyl)ethynyl)benzene, and the specific method is as follows:

[0069]

[0070] By replacing the 4-pentylphenylacetylene in Example 1 with 4-(4-n-pentylcyclohexyl)phenylacetylene, and using the same synthesis method as in Example 1 for other operations, 2,5-difluoro-1-isothiocyanate-4-((4-(4-n-pentylcyclohexyl)phenyl)acetylene)benzene was obtained.

[0071] The structural assessment data is as follows:

[0072] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.896 (t, 3H, J = 7.5Hz), 1.002 ~ 1.084 (m, 2H), 1.197 ~ 1.352 (m, 9H), 1.391 ~ 1.474 (m, 2H), 1.864 ~ 1.885 (m, 4H), 2 .474(t,3H,J=12Hz),6.898(dd,1H,J1=8.5Hz,J2=6.5Hz),7.198(d,2H,J=8Hz),7.252(dd,1H,J1=9.5Hz,J2=6.0Hz),7.447(d,2H,J=8.5Hz).

[0073] 13 C NMR (125MHz, CDCl3) δ (ppm): 14.1, 22.7, 26.7, 32.2, 33.5, 34.1, 37.3, 37.4, 44.7, 80.4, 97.5, 112.0 (dd, J1 = 19Hz, J2 = 10Hz), 113.1 (d, J = 26Hz) ,119.3,119.7(dd,J1=22Hz,J2=4.5Hz),120.9(dd,J1=21Hz,J2=14Hz),127.1,131.8,143.5,149.5,154.7(d,J=252.5Hz),158.3(d,J=265Hz).

[0074] MS m / z (RI,%): 423.2 (M + ,100.0),310.1(11.6),297.1(39.3),284.1(25.1),252.1(13.1).DSC:C 61.5N 236.3I.

[0075] According to DSC test data, the nematic phase temperature range of this liquid crystal compound reaches 174.8℃.

[0076] Example 3:

[0077] This example describes the synthesis of 2,5-difluoro-1-isothiocyanate-4-((4-(4-n-propylcyclohexyl)phenyl)ethynyl)benzene:

[0078]

[0079] By replacing 4-pentylphenylacetylene in Example 1 with 4-(4-n-propylcyclohexyl)phenylacetylene, and using the same synthesis method as in Example 1 for other operations, 2,5-difluoro-1-isothiocyanate-4-((4-(4-n-propylcyclohexyl)phenyl)acetylene)benzene was obtained.

[0080] The structural assessment data is as follows:

[0081] 1H NMR (500MHz, CDCl3) δ (ppm): 0.902 (t, 3H, J = 7.5Hz), 1.004 ~ 1.087 (m, 2H), 1.163 ~ 1.453 (m, 7H), 1.857 ~ 1.892 (m, 4H), 2.476 (t, 3H) ,J=12Hz),6.902(dd,1H,J1=8.5Hz,J2=6.5Hz),7.201(d,2H,J=8Hz),7.256(dd,1H,J1=9.5Hz,J2=6.0Hz),7.450(d,2H,J=8.5Hz).

[0082] 13 C NMR (125MHz, CDCl3) δ (ppm): 14.4, 20.0, 30.0, 33.5, 37.0, 39.7, 44.7, 80.4, 97.5, 112.0 (dd, J1 = 19Hz, J2 = 10Hz), 113.1 (d, J = 26Hz), 119 .3,119.7(dd,J1=22Hz,J2=4.5Hz),120.9(dd,J1=21Hz,J2=14Hz),127.1,131.8,143.5,149.5,154.7(d,J=250Hz),158.3(d,J=250Hz).

[0083] MS m / z (RI,%): 395.3 (M + , 100.0), 310.1(13.8), 297.1(37.8), 284.1(21.9), 252.1(18.5).DSC: C79.5 N 242.1I.

[0084] According to DSC test data, the nematic phase temperature range of this liquid crystal compound reaches 162.6℃.

[0085] Example 4:

[0086] This example describes the synthesis of 4-n-butyl-4'-((2,5-difluoro-4-isothiocyanate-phenyl)ethynyl)-1,1'-biphenyl:

[0087]

[0088] 4-n-butyl-4-ethynylbiphenyl was used to replace 4-n-pentylphenylacetylene in Example 1, and the other operations were carried out using the same synthesis method as in Example 1, to obtain 4-n-butyl-4'-((2,5-difluoro-4-isothiocyanate-phenyl)ethynyl)-1,1'-biphenyl.

[0089] The structural assessment data is as follows:

[0090] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.945 (t, 3H, J = 7.5Hz), 1.363 ~ 1.425 (m, 2H), 1.617 ~ 1.663 (m, 2H), 2.652 (t ,2H,J=8Hz),6.908(dd,1H,J1=9Hz,J2=6Hz),7.242-7.288(m,3H),7.513(d,2H,J=8.0Hz),7.582(s,4H).

[0091] 13 C NMR (125MHz, CDCl3) δ (ppm): 14.0, 22.4, 33.6, 35.3, 81.6, 97.2, 111.8 (dd, J1=17.5Hz, J2=10Hz), 113.1 (d, J=26Hz), 119.7 (dd, J1=22Hz, J2=2.4H z),120.5,121.1(dd,J1=17.5Hz,J2=10Hz),126.9,126.9,129.0,132.2, 137.4, 141.9, 142.9, 143.6, 154.7 (d, J = 257.5Hz), 158.3 (d, J = 248.8Hz).

[0092] MS m / z (RI,%): 403.2 (M + ,87.0),360.1(100),180.1(12.6).

[0093] DSC: C59.5 S 164.6N 226.7I.

[0094] Example 5:

[0095] This example describes the synthesis of 4-n-pentyl-4'-((2,5-difluoro-4-isothiocyanate-phenyl)ethynyl)-1,1'-biphenyl:

[0096]

[0097] 4-n-pentyl-4-ethynylbiphenyl was used to replace 4-n-pentylphenylacetylene in Example 1, and other operations were performed using the same synthetic method as in Example 1 to obtain 4-n-pentyl-4'-((2,5-difluoro-4-isothiocyanate-phenyl)ethynyl)-1,1'-biphenyl.

[0098] The structural assessment data is as follows:

[0099] 1H NMR (500MHz, CDCl3) δ (ppm): 0.906 (t, 3H, J = 7.5Hz), 1.33 ~ 1.362 (m, 4H), 1.625 ~ 1.683 (m, 2H), 2.646 (t, 2H, J=8Hz), 6.908 (dd, 1H, J1=9Hz, J2=6Hz), 7.250-7.298 (m, 3H), 7.519 (d, 2H, J=8.0Hz), 7.589 (s, 4H).

[0100] 13 C NMR (125MHz, CDCl3) δ (ppm): 14.0, 22.6, 31.2, 31.5, 35.6, 81.6, 97.2, 111.8 (dd, J1=17.5Hz, J2=10Hz), 113.1 (d, J=26Hz), 119.7 (dd, J1=22Hz, J2=2. 4Hz),120.5,121.1(dd,J1=17.5Hz,J2=10Hz),126.9,126.9,129.0,132.2 ,137.4,141.9,142.9,143.6,154.7(d,J=257.5Hz),158.3(d,J=248.8Hz).

[0101] MS m / z (RI,%): 417.1 (M + ,75.4),360.0(100.0),180.0(13.1).

[0102] DSC: C 63.7S 175.6N 225.3 ISO.

[0103] Example 6:

[0104] This example describes the synthesis of 2,5-difluoro-4-isothiocyanate-4”-n-pentyl-1,1':4',1”-terphenyl:

[0105]

[0106] Synthesis steps:

[0107] Synthesis Step 1: Under nitrogen protection, 25.5 g of 2,5-difluoro-4-iodoaniline (synthesized in Example 1), 26.8 g of 4'-pentylbiphenylboronic acid, 1.2 g of tetrakis(triphenylphosphine)palladium, 27.6 g of potassium carbonate, 100 ml of toluene, 100 ml of ethanol, and 100 ml of water were added to a reaction vessel. The mixture was stirred and heated to reflux for 8 h. After cooling to room temperature, 100 mL of toluene was added, and the organic layer was separated. The organic layer was washed with water until neutral, concentrated to remove the solvent, and the obtained product was recrystallized from petroleum ether to obtain 28.8 g of brown solid.

[0108] Synthesis Step 2: Add 28.8 g of the brown solid obtained in the previous step to a reaction vessel, add 200 mL of chloroform and 50 mL of water, cool to below 5 °C, and slowly add 14.1 g of sulfur phosgene. After the addition is complete, heat to reflux for 2 h, cool to room temperature, separate the layers, wash the organic layer with sodium bicarbonate aqueous solution, then wash with water until neutral, remove the solvent by vacuum distillation, pass the obtained product through a silica gel column, elute with n-heptane, recrystallize the product with n-heptane to obtain 25.2 g of white solid with a gas chromatographic purity of 99.9%.

[0109] The synthesis route is shown below:

[0110]

[0111] The structural assessment data is as follows:

[0112] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.907 (t, 3H, J = 7.5Hz), 1.337 ~ 1.379 (m, 4H), 1.625 ~ 1.683 (m, 2H), 2.644 (t, 2H, J = 7.5Hz), 6.955 (dd, 1H, J1 =10Hz, J2=6Hz), 7.230 (dd, 1H, J1 = 11Hz, J2 = 4Hz), 7.258 (d, 2H, J = 8Hz), 7.524 (d, 2H, J = 8Hz), 7.539 (d, 2H, J = 8Hz), 7.645 (d, 2H, J = 8Hz).

[0113] 13 C NMR (125MHz, CDCl3) δ (ppm): 14.1, 22.6, 31.2, 31.6, 35.6, 113.8 (d, J = 28Hz), 117.2 (dd, J1 = 21Hz, J2 = 5Hz), 119.9 (dd, J1 = 15Hz, J2 = 12Hz), 126.9, 127.2, 128.7 (dd, J1=16Hz, J2=7Hz), 129.0, 129.1 (d, J=4Hz), 132.3, 137.5, 141.5, 142.7, 142.9, 155.2 (d, J=250Hz).

[0114] MS m / z (RI,%): 393.1 (M + ,100),336.1(94).

[0115] DSC: C64.0 S 138.1 N 174.9 I.

[0116] Example 7:

[0117] This example describes the synthesis of 2,5-difluoro-4-isothiocyanate-4'-(4-n-propylcyclohexyl)-1,1'-biphenyl:

[0118]

[0119] By replacing 4'-pentylbiphenylboronic acid in Example 6 with 4-(trans-4-n-propylcyclohexyl)phenylboronic acid, and performing the same synthesis method as in Example 6, 2,5-difluoro-4-isothiocyanate-4'-(4-n-propylcyclohexyl)-1,1'-biphenyl was obtained.

[0120] The structural assessment data is as follows:

[0121] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.904 (t, 3H, J = 7.5Hz), 1.014 ~ 1.098 (m, 2H), 1.196 ~ 1.501 (m, 7H), 1.856 ~ 1.921 (m, 4H), 2.467 ~ 2.5 52(m,1H),6.930(dd,1H,J1=8.5Hz,J2=6Hz),7.193(dd,1H,J1=9.5Hz,J2=6.5Hz),7.272(d,2H,J=8.5Hz),7.405(d,2H,J=8Hz).

[0122] 13 C NMR (125MHz, CDCl3) δ (ppm): 14.5, 20.1, 33.6, 34.3, 37.1, 39.8, 44.4, 113.7 (d, J = 29Hz), 117.2 (dd, J1 = 21Hz, J2 = 5Hz), 119. 5(dd,J1=16Hz,J2=12Hz),127.3,128.7(d,J=3Hz),129.2(dd,J1=16Hz,J2=6.5Hz),131.2,142.8,148.7,155.1(d,J=250Hz).

[0123] DSC: C88.5 N 186.4I.

[0124] Example 8:

[0125] This example describes the synthesis of 2,5-difluoro-4-isothiocyanate-4'-((4-n-propylphenyl)ethynyl)-1,1'-biphenyl:

[0126]

[0127] By replacing 4'-pentylbiphenylboronic acid in Example 6 with 4-((4-propylphenyl)ethynyl)phenylboronic acid, and performing the same synthesis method as in Example 6, 2,5-difluoro-4-isothiocyanate-4'-((4-n-propylphenyl)ethynyl)-1,1'-biphenyl was obtained.

[0128] The structural assessment data is as follows:

[0129] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.943 (t, 3H, J = 7.5Hz), 1.611 ~ 1.685 (m, 2H), 2.601 (t, 2H, J = 7.5Hz), 6.972 (dd, 1H, J1 = 10Hz, J2 = 6Hz), 7.165 (d, 2H, J = 8Hz), 7.231 (dd, 1H, J1 = 10Hz, J2 = 7Hz), 7.452 (d, 2H, J = 8Hz), 7.452 (d, 2H, J = 8Hz), 7.582 ((d, 2H, J = 8Hz).

[0130] 13 C NMR (125MHz, CDCl3) δ (ppm): 13.8, 24.3, 38.0, 88.2, 91.2, 113.8 (d, J = 28Hz), 117.1 (dd, J1 = 21Hz, J2 = 5Hz), 120.2, 120.3 (dd, J1 = 16 Hz, J2=11Hz),124.0,128.3(dd,J1=21.4,J2=5Hz),128.6,128.7(d,J=4Hz),131.6,131.8,133.2,143.1,143,5,155.1(d,J=250Hz)

[0131] MS m / z (RI,%): 389.1 (M + ,100),360.1(85).

[0132] DSC: C 103.5N 212.5I.

[0133] Example 9:

[0134] This example describes the synthesis of 2,5-difluoro-4-isothiocyanate-1-((4-(3-butenyl)phenyl)ethynyl)benzene:

[0135]

[0136] By replacing 4-pentylphenylacetylene in Example 1 with 4-(3-butenyl)phenylacetylene, and using the same synthesis method as in Example 1 for other operations, 2,5-difluoro-4-isothiocyanate-1-((4-(3-butenyl)phenyl)acetylene)benzene was obtained.

[0137] The structural assessment data is as follows:

[0138] 1 H NMR (500MHz, CDCl3) δ (ppm): 2.352~2.293 (m, 2H), 2.272 (t, J = 7.5Hz, 2H), 4.974~5.048 (m, 2H), 5.790~5 .871(m,1H),6.886~6.916(m,1H),7.183(d,J=8.0Hz,2H),7.240~7.258(m,1H),7.451(d,J=8.0Hz,2H).

[0139] 13 C NMR (125MHz, CDCl3) δ (ppm): 35.2, 35.4, 80.6, 97.4, 111.9 (dd, J1 = 19Hz, J2 = 8Hz), 113.1 (d, J = 26Hz), 115.3, 119.5, 119. 7(d,J=22Hz),121.0(dd,J1=16Hz,J2=11Hz),128.7,131.8,137.6,143.4,143.5,154.7(d,J=250Hz),158.3(d,J=250Hz).

[0140] MS m / z (RI,%): 325.1 (M + ,100),284.0(91).

[0141] DSC: C 29.0N 47.8I.

[0142] Example 10:

[0143] This example describes the synthesis of 4-(4-((2,5-difluoro-4-isothiocyanate-phenyl)ethynyl)biphenyl)-4'-pentyl-1,1'-bicyclohexane:

[0144]

[0145] 4-(4-ethynylphenyl)-4'-pentyl-1,1'-bicyclohexane was used to replace 4-pentylphenylacetylene in Example 1, and other operations were performed using the same synthetic method as in Example 1 to obtain 4-(4-((2,5-difluoro-4-isothiocyanate-phenyl)ethynyl)biphenyl)-4'-pentyl-1,1'-bicyclohexane.

[0146] The structural assessment data is as follows:

[0147] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.821 ~ 0.896 (m, 5H), 0.952 ~ 1.317 (m, 17H), 1.716 ~ 1.910 (m, 8H), 2.446 (t, J = 12Hz, 1H), 6.886(dd,J1=8.5Hz,J2=6.5Hz,1H),7.183(d,J=8Hz,2H),7.240(dd,J1=8.5Hz,J2=6.5Hz,1H),7.434(d,J=8Hz,2H).

[0148] 13 C NMR (125MHz, CDCl3) δ (ppm): 14.1, 22.7, 26.7, 30.1, 30.3, 32.3, 33.7, 34.4, 37 .5,38.0,42.9,43.4,44.7,80.4,97.6,111.9(dd,J1=19Hz,J2=10Hz),112.9,1 13.0(d,J=26Hz),119.3,119.7(dd,,J1=22Hz,J2=4.5Hz),120.8(dd,J1=21Hz, J2=14Hz),127.0,131.8,143.6,149.5,154.6(d,J=250Hz),158.3(d,J=250Hz).

[0149] DSC: C96.6 N 306.6I.

[0150] Example 11:

[0151] This example describes the synthesis of 2,5-difluoro-4-isothiocyanate-1-((4-((4-pentylphenyl)ethynyl)phenyl)ethynyl)benzene:

[0152]

[0153] By replacing the 4-pentylphenylacetylene in Example 1 with 4-((4-pentylphenyl)ethynyl)phenylacetylene, and performing the other operations in the same synthetic method as in Example 1, 2,5-difluoro-4-isothiocyanate-1-((4-((4-pentylphenyl)ethynyl)phenyl)ethynyl)benzene was obtained.

[0154] DSC: C 128.2S 166.7N 245.5I.

[0155] Example 12:

[0156] This example describes the synthesis of 4-((2,5-difluoro-4-isothiocyanate-phenyl)ethynyl)-2,5-difluoro-4'-propyl-1,1'-biphenyl:

[0157]

[0158] 4-((2,5-difluoro-4'-propyl-1,1'-biphenyl)-2,5-difluoro-4'-propyl-1,1'-biphenyl was used instead of 4-ethynyl-2,5-difluoro-4'-propyl-1,1'-biphenyl, and the other operations were performed using the same synthetic method as in Example 1, to obtain 4-((2,5-difluoro-4-isothiocyanate-phenyl)ethynyl)-2,5-difluoro-4'-propyl-1,1'-biphenyl.

[0159] The structural assessment data is as follows:

[0160] 1 H NMR (500MHz, CDCl3) δ (ppm): 0.972 (t, J = 8Hz, 3H), 1.643 ~ 1.718 (m, 2H), 2.673 (t, J = 8Hz, 2H), 6.932 (dd, J 1=9Hz, J2=6.5Hz, 1H), 7.201 (dd, J1=9.5Hz, J2=6.5Hz, 1H), 7.251~7.309 (m, 4H), 7.461 (d, J=6.5Hz, 2H).

[0161] 13 C NMR (125MHz, CDCl3) δ (ppm): 13.9, 24.4, 37.8, 86.8, 89.4, 110.1 (dd, J1 = 19Hz, J2 = 11Hz), 110.8 ( dd, J1=19Hz, J2=11Hz) 113.2 (d, J=26Hz), 116.9 (d, J=12Hz), 120.0 (dd, J1=40.6Hz, J2=27.5Hz), 122.0(dd,J1=16Hz,J2=11Hz),128.7(d,J=4Hz),128.8,131.3,132.0,131.9(dd,J1=16Hz,J2=9H z),143.6,144.0,154.6(d,J=250Hz),155.1(d,J=254Hz),158.5(d,J=254Hz),158.9(d,J=254Hz)

[0162] MS m / z (RI,%): 425.1 (M + ,100),396.1(95).

[0163] DSC: C 82.9N 214.5 I.

[0164] Example 13:

[0165] This embodiment is a high-frequency performance test of the compound of the present invention:

[0166] Prepare a liquid crystal composition M0, which is composed of the monomeric liquid crystal compounds shown in Table 1 below.

[0167] Table 1

[0168]

[0169] The liquid crystal compounds of Examples 2 and 5 were mixed with M0 at a mass ratio of 15:85 to obtain liquid crystal compositions M1 and M2.

[0170] M0 to M2 were respectively filled into polytetrafluoroethylene tubes, and the dielectric constant and loss tangent at 19 GHz were tested using the cavity perturbation method at 25 ℃. The quality factor was calculated, and the results are shown in Table 2 below.

[0171] Table 2 Dielectric constant and dielectric loss test at 19GHz

[0172] Composition <![CDATA[ε ⊥ ]]> <![CDATA[ε ∥ ]]> Δε <![CDATA[tanδ ⊥ ]]> <![CDATA[tanδ ∥ ]]> η M0 2.361 2.989 0.628 0.0106 0.0049 19.82 M1 2.589 3.347 0.772 0.0096 0.0048 24.02 M2 2.355 3.428 0.838 0.0098 0.0050 24.94

[0173] The test data shows that the tanδ values ​​of liquid crystal compositions M1-M2 after applying the compound of the present invention are greater than those of M0. ⊥ There is a significant decrease, Δε increases, and η increases significantly.

[0174] Comparative Example 1:

[0175] The structural formula of a compound with two lateral fluorine atoms at the molecular end that has been disclosed is shown below:

[0176]

[0177] The synthesis of this compound follows the method described in the literature "Catanescu, O., Chien L.-C. High birefringence difluoroisothiocyanate biphenyl tolane liquid crystals". Liquid Crystals Synthesized using the method described in 2006, 33(1):115-120.

[0178] The liquid crystal phase transition temperature of this compound is C62.2 N 218.2 I, and the nematic phase temperature range is 156℃.

[0179] The compound was dissolved in the base formulation HOST at a mass ratio of 15:85. The birefringence Δn of the compound was measured to be 0.3646, and the rotational viscosity γ1 was measured to be 505 mPa·s.

[0180] Example 2 of the present invention: Liquid crystal compound:

[0181]

[0182] The liquid crystal phase transition temperature is: C 61.5 N 236.3 I, and the nematic phase temperature reaches 174.8℃.

[0183] The compound from Example 2 was dissolved in the base formulation HOST at a mass ratio of 15:85. The birefringence Δn of the compound from Example 2 was measured to be 0.3786; the rotational viscosity γ1 was 457 mPa·s.

[0184] It can be seen that the liquid crystal compound of Example 2 of the present invention has a higher liquid crystal clearing point and a wider nematic liquid crystal phase temperature range than the compound of Comparative Example 1; at the same time, the compound of Example 2 of the present invention has a higher birefringence and a lower rotational viscosity than the compound of Comparative Example 1.

[0185] Comparative Example 2:

[0186] The structural formula of a compound with two lateral fluorine atoms at the molecular end that has been disclosed is shown below:

[0187]

[0188] The synthesis of this compound follows the method described in the literature "Catanescu, O., Chien L.-C. High birefringence difluoroisothiocyanate biphenyl tolane liquid crystals". Liquid Crystals Synthesized using the method described in "2006, 33(1):115-120."

[0189] The liquid crystal phase transition temperature of this compound is: C 60.7 S 120.2 N 210.9 I, and the liquid crystal phase temperature range is 150.2℃.

[0190] The compound was dissolved in the base formulation HOST at a mass ratio of 15:85. The birefringence Δn of the compound was measured to be 0.4784; the rotational viscosity γ1 was 408 mPa·s.

[0191] Example 5 of the present invention: Liquid crystal compound:

[0192]

[0193] The liquid crystal phase transition temperature of the compound in Example 5 is: C 63.7 S 175.6 N 225.3 I, and the liquid crystal phase temperature range is 161.6℃.

[0194] The compound from Example 5 was dissolved in the base formulation HOST at a mass ratio of 15:85. The birefringence Δn of the compound from Example 5 was measured to be 0.5093; the rotational viscosity γ1 was 404 mPa·s.

[0195] It can be seen that the liquid crystal compound of Example 5 of the present invention has a higher liquid crystal clearing point and a wider liquid crystal phase temperature range than the compound of Comparative Example 2; at the same time, the compound of Example 5 of the present invention has a higher birefringence and a lower rotational viscosity than the compound of Comparative Example 2.

Claims

1. A liquid crystal compound containing 2,5-difluorosubstituted benzene, characterized in that, The structure of the compound is shown in Formula I, and the structure of the compound shown below is also shown: ； Ⅰ In Formula I: R is an alkyl group with 1 to 10 carbon atoms, or an alkyl group in which hydrogen is substituted by fluorine; Z1 is a single bond; Z2 is -C≡C-; n=1; ring A is cyclohexane; ring B is a benzene ring, or a benzene ring in which hydrogen is substituted by fluorine, chlorine, methyl, or / and ethyl.

2. The liquid crystal compound according to claim 1, characterized in that, The compound has the structural formula shown in any of the following structures; 。 3. The application of the compound of claim 1 in the preparation of optoelectronic devices and display devices.

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