阅读说明：本技术 用于高频技术的液晶介质及其组件 (Liquid crystal medium for high-frequency technology and assembly thereof ) 是由 李娟利 李建 安忠维 万丹阳 莫玲超 张璐 胡明刚 车昭毅 杨晓哲 于 2020-04-14 设计创作，主要内容包括：本发明提出一种用于高频技术的液晶介质及其组件。其中,液晶化合物的结构通式如式(Ⅰ)所示：其中,环A为环己基或环己烯基；R-(1)是碳原子数为1～9的直链烷基、直链烷氧基、直链氟代烷基,或碳原子数为2～9的链烯基、链烯氧基或二氟乙烯基中的一种；X-(1)～X-(6)为-H或-CH-(3),且至少有一个为-CH-(3)；m为0或1。本发明的液晶化合物具有低的熔点、低的介电损耗、高的调谐率和较低的旋转粘度的优点,将其添加到混合液晶中形成的向列相液晶组合物不仅具有低的介电损耗和高的调谐率,还具有宽的向列相温度区间、低的熔点以及较低的旋转粘度,用于高频组件可提升高频组件性能,尤其适用于智能天线液晶移相器以及5G通信网路领域。(The invention provides a liquid crystal medium for high-frequency technology and a component thereof. Wherein, the structural general formula of the liquid crystal compound is shown as the formula (I): wherein ring A is cyclohexyl or cyclohexenyl; r 1 Is one of a C1-9 linear alkyl group, a linear alkoxy group, a linear fluoroalkyl group, or a C2-9 alkenyl group, an alkenyloxy group, or a difluorovinyl group; x 1 ～X 6 is-H or-CH 3 And at least one is-CH 3 (ii) a m is 0 or 1. The liquid crystal compound has low melting point and low dielectric lossThe nematic liquid crystal composition formed by adding the nematic liquid crystal composition into mixed liquid crystal has the advantages of low dielectric loss, high tuning rate, wide nematic phase temperature range, low melting point and low rotational viscosity, can improve the performance of high-frequency components when being used for high-frequency components, and is particularly suitable for the fields of intelligent antenna liquid crystal phase shifters and 5G communication networks.)

1. A liquid crystal compound is characterized in that the structural general formula of the liquid crystal compound is shown as formula (I):

wherein ring A is cyclohexyl or cyclohexenyl; r ₁Is one of a C1-9 linear alkyl group, a linear alkoxy group, a linear fluoroalkyl group, or a C2-9 alkenyl group, an alkenyloxy group, or a difluorovinyl group; x₁～X₆is-H or-CH₃And at least one is-CH₃(ii) a m is 0 or 1.

2. The liquid crystal compound according to claim 1, wherein the structure of the liquid crystal compound is one of the following formulae:

wherein R is₁Is a linear alkyl group having 1 to 9 carbon atoms or an alkenyl group having 2 to 7 carbon atoms; x₁～X₆is-H or-CH₃And at least one is-CH₃。

3. The liquid crystal compound according to claim 2, wherein the structure of the liquid crystal compound is one of the following formulae:

wherein R is₁Is a linear alkyl group having 1 to 9 carbon atoms or an alkenyl group having 2 to 7 carbon atoms.

4. The liquid crystal compound according to claim 1, wherein the structure of the liquid crystal compound is one of the following formulae:

wherein R is₁Is a linear alkyl group having 1 to 9 carbon atoms or an alkenyl group having 2 to 7 carbon atoms; x₁～X₆is-H or-CH₃And at least one is-CH₃。

5. The liquid crystal compound according to claim 4, wherein the structure of the liquid crystal compound is one of the following formulae:

Wherein R is₁Is a linear alkyl group having 1 to 9 carbon atoms or an alkenyl group having 2 to 7 carbon atoms.

6. A liquid crystal composition comprising 1 to 90% of a liquid crystal compound represented by the general formula (I), 1 to 60% of a liquid crystal compound represented by the general formula (II), and 0 to 50% of a liquid crystal compound represented by the general formula (III):

wherein ring A is cyclohexyl or cyclohexenyl; r₁Is a linear alkyl group, a linear alkoxy group, a linear fluoroalkyl group having 1 to 9 carbon atoms, or an alkenyl group, an alkenyloxy group or a di-alkyl group having 2 to 9 carbon atomsOne of a fluorovinyl group; x₁～X₆is-H or-CH₃And at least one is-CH₃(ii) a m is 0 or 1;

wherein R is₂、R₃Each of which is a linear alkyl group, a linear alkoxy group, or a fluoroalkyl group having 1 to 9 carbon atoms, or an alkenyl group, an alkenyloxy group, or a difluorovinyl group having 2 to 9 carbon atoms; b is a single bond, an ethane bridge bond or a carbon-carbon triple bond; x₇～X₁₃is-H or-CH₃And at least one is-CH₃(ii) a n and p are 0 or 1.

7. The liquid crystal composition according to claim 6, wherein the liquid crystal compound represented by the general formula (II) is 10 to 50% and the liquid crystal compound represented by the general formula (III) is 5 to 40%.

8. A high-frequency component, characterized in that it comprises a liquid crystal compound according to any one or more of claims 1 to 5, or a liquid crystal composition according to any one of claims 6 to 7.

9. A process for the preparation of a liquid-crystalline compound as claimed in any of claims 1 to 5, characterized in that it employs the following synthetic route:

the method comprises the following steps:

s1, sequentially adding the raw material (1), calcium carbonate and water into a reaction bottle, adding elemental iodine at the temperature of-5 ℃, and reacting for 2 hours under heat preservation for post-treatment; filtering the reaction solution, extracting the filtrate with toluene, washing the filtrate to be neutral, drying the filtrate with anhydrous magnesium sulfate, filtering, performing rotary evaporation on the filtrate to remove the toluene, and adding a mixed solution of toluene and n-heptane for recrystallization to obtain an intermediate (2);

s2, under the protection of nitrogen, adding the intermediate (2), the raw material (3), bis (triphenylphosphine) palladium dichloride, TBAB and K into a reaction bottle₂CO₃Toluene, ethanol, water; carrying out reflux reaction for 4h, and then cooling to room temperature for post-treatment; standing and layering the reaction solution, adding toluene into the lower layer for extraction, combining organic phases, washing the organic phases to be neutral, drying the organic phases with anhydrous magnesium sulfate, filtering, and performing recrystallization after rotary evaporation of the filtrate to obtain an intermediate 5; or under the protection of nitrogen, adding the intermediate (2), the raw material (4), bis (triphenylphosphine) palladium dichloride, cuprous iodide, triphenylphosphine and triethylamine into a reaction bottle, reacting for 2 hours, and then carrying out aftertreatment; filtering the reaction solution, carrying out rotary evaporation on the filtrate to remove triethylamine, adding toluene to dissolve, washing with water to be neutral, drying with anhydrous magnesium sulfate, filtering, and carrying out recrystallization on the filtrate after rotary evaporation to obtain an intermediate (5);

S3, adding the intermediate (5), acetone and water into a three-necked bottle, dropwise adding thiophosgene at room temperature, reacting at room temperature for 1 hour after the thiophosgene is added, and monitoring by TLC to stop the reaction when no raw material remains; and (3) carrying out rotary evaporation, adding toluene to dissolve the obtained crude product, washing with water to neutrality, drying with anhydrous magnesium sulfate, filtering, carrying out rotary evaporation, dissolving with n-heptane, and carrying out column chromatography purification to obtain the target compound (6).

10. The method according to claim 9, wherein in step S1, the molar ratio of the raw material (1), the calcium carbonate and the iodine is 1:1.3 (1-0.95), and the reaction temperature is-5-50 ℃; in the step S2, the molar ratio of the intermediate (2) to the raw material (3) is 1 (1-1.3), the temperature of the Suzuki coupling reaction is 0-90 ℃, and the intermediate (2) is bis (triphenylphosphine) palladium dichloride, TBAB: K₂CO₃The molar ratio of (1), (0.1% -3%) (0.1-0.5) to (1-5); or in the step S2, the molar ratio of the intermediate (2) to the raw material (4) is 1 (1-1.1), the Soniganshira coupling reaction temperature is 0-50 ℃, and the molar ratio of the intermediate (2) to bis (triphenylphosphine) dichloride to cuprous iodide to triphenylphosphine is 1 (0.1-3%) (0.3-9%); in step S3, the molar ratio of the intermediate (5) to the thiophosgene is 1 (1-2).

Technical Field

The invention belongs to the technical field of liquid crystal materials, and particularly relates to an alkyne liquid crystal compound, a composition thereof and a high-frequency component comprising the alkyne liquid crystal compound, which are suitable for the fields of filters, adjustable frequency selection surfaces, phase shifters, phased array radars, satellite navigation, 5G communication networks and the like.

Background

In recent years, liquid crystal materials with low dielectric loss and high dielectric tuning rate have attracted attention for application in liquid crystal microwave device technologies such as smart antennas, filters, tunable frequency selective surfaces, phase shifters, phased array radars, 5G communication networks, and the like.

The dielectric loss of the liquid crystal material is an important factor influencing the insertion loss of the microwave device, and in order to obtain a high-quality liquid crystal microwave device, the dielectric loss of the liquid crystal material must be reduced as much as possible. For a liquid crystal material, the loss tangent varies with the liquid crystal molecules according to the electric field direction, i.e., the loss in the long axis direction and the short axis direction of the liquid crystal molecules varies, and the maximum loss value is generally used as the dielectric loss value of the liquid crystal material when calculating the loss of the liquid crystal material. In addition, the dielectric tuning rate of the liquid crystal material determines the max (tan δ) of the microwave device_∥,tanδ_⊥) The dielectric tuning rate of the liquid crystal material is determined by the dielectric anisotropy (. DELTA.. di-elect cons.) of the liquid crystal material under microwave and the dielectric constant (. di-elect cons.) in the direction parallel to the molecules_∥) Is determined by the ratio of:

τ＝Δε/ε_∥

in order to comprehensively evaluate the performance of the liquid crystal material under high frequency, a quality factor (eta) is introduced:

η＝τ/max(tanδ_∥,tanδ_⊥)

that is, the smaller the loss of the liquid crystal material and the larger the tuning rate, the larger the quality factor, indicating the better the performance of the liquid crystal material.

The nematic phase temperature range of the liquid crystal material determines the working temperature range of the liquid crystal microwave device, and the wider nematic phase temperature interval of the liquid crystal material means the wider working temperature range of the microwave device. The rotational viscosity of the liquid crystal material determines the response speed of the microwave device, the smaller the rotational viscosity is, the faster the response speed is, and in order to meet the requirement of fast switching operation of a high-frequency component, the liquid crystal material needs to have lower rotational viscosity.

In order to satisfy the requirement that the high-frequency component works under the driving of an electric field, the liquid crystal material is required to have a proper dielectric constant under a low frequency, such as 1 KHz. Since the dielectric constant of a liquid crystal material at high frequencies is related to the birefringence of the liquid crystal, it is shown by the following formula:

in order to obtain a higher dielectric constant, a liquid crystal material having a high birefringence is also required. The isothiocyanic liquid crystal compound has higher birefringence and larger dielectric anisotropy compared with the conventional fluorine-containing liquid crystal, has higher birefringence and lower rotational viscosity compared with cyano-based liquid crystal, and particularly has lower dielectric loss.

Merck discloses in a patent application No. 201510482208.6 entitled "liquid Crystal Medium and high frequency Module comprising the same" composition M-1 of example 1 suitable for microwave Range applications, formed from a liquid crystalline compound containing fluorinated tolanylidene isothiocyanate and fluorinated phenyl tolanylidene isothiocyanate, having a low rotational viscosity at 20 ℃ of 270 mPas, but a high dielectric loss at 19GHz of 0.0143. The patent discloses that the composition M-4 of example 4, applied in the microwave range, formed from a liquid crystal compound of fluorinated tolytene isothiocyanate, fluorinated terphenyl isothiocyanate and fluorinated phenyl tolytene isothiocyanate, has a rotational viscosity of 698mPa s at 20 ℃ and a dielectric loss of 0.0189 at 19 GHz.

Merck corporation, in "proc.ofspie, 2013, 8642: 86420S-1-86420S-6, entitled "Liquid Crystals for microwave applications" reported that Liquid crystal molecules with a bis-tolane skeleton have high tuning rate and low dielectric loss, but the Liquid crystal molecules with the bis-tolane skeleton have the problems of large rotational viscosity, high melting point and poor compatibility, and the application of the Liquid crystal molecules in mixed Liquid crystal formulations is limited. For example, in the journal "Liquid crystals, 2000, 27 (2): 283-287 ", entitled" Synthesis of chiral understated biostolane liquid crystals ", reports liquid crystal compounds of the bis-diphenylacetylene, the typical structural formula of which is shown below:

the thermal performance data is Cr 143.2N 192.4I, namely the melting point value is as high as 143.2 ℃. The melting point can be further reduced by extending the terminal flexible chain and introducing larger substituents such as ethyl groups laterally, for example "Liquid crystals, 2000, 27 (2): 283-287 ", entitled" Synthesis of chiral and chiral thiostilbene liquid crystals ", reports the laterally ethyl-substituted bis-diphenylacetylene liquid crystal compound PTP (2) TP-6-3, having the structural formula shown below:

the thermal data is Cr 20.0N 107.8I, i.e. the melting point is reduced to 20.0 ℃. The rotational viscosity values of the compounds at 20 ℃ of up to 2100 mPas are disclosed in the patent with the title "component and liquid-crystalline medium for high-frequency technology" filed under the name of Merck, Inc. No. 201080041956.6.

In the patent of Merck, Inc. No. 201280063201.5, entitled "liquid Crystal Medium and high frequency Components containing it", a liquid Crystal mixture M-1 for use in the microwave range is disclosed, consisting of the compound PTP (2) TP-6-3 and a fluorine-containing tolane compound, the rotational viscosity at 20 ℃ of which is reduced to 718mPa · s, the tuning ratio at 30GHz of 0.25, and the dielectric loss of which is 0.0128. Although the tuning rate, the dielectric loss and the rotational viscosity are improved to a certain extent, the tuning rate is still low, the dielectric loss is still high, and the comprehensive performance needs to be further improved.

Disclosure of Invention

Technical problem to be solved

In order to overcome the drawbacks or disadvantages of the background art, the present invention proposes a liquid crystal compound having low dielectric loss, high tuning rate, low melting point, wide nematic phase temperature range and low rotational viscosity, a composition comprising the same, and a high frequency device comprising the same.

(II) technical scheme

In order to solve the technical problems, the invention provides a liquid crystal compound, and the structural general formula of the liquid crystal compound is shown as the formula (I):

wherein ring A is cyclohexyl or cyclohexenyl; r₁Is one of a C1-9 linear alkyl group, a linear alkoxy group, a linear fluoroalkyl group, or a C2-9 alkenyl group, an alkenyloxy group, or a difluorovinyl group; x ₁～X₆is-H or-CH₃And at least one is-CH₃(ii) a m is 0 or 1.

Further, the structure of the liquid crystal compound is one of the following formulas:

wherein R is₁Is a straight-chain alkyl group having 1 to 9 carbon atoms or an alkene having 2 to 7 carbon atomsA group; x₁～X₆is-H or-CH₃And at least one is-CH₃。

Further, the structure of the liquid crystal compound is one of the following formulas:

wherein R is₁Is a linear alkyl group having 1 to 9 carbon atoms or an alkenyl group having 2 to 7 carbon atoms.

Further, the structure of the liquid crystal compound is one of the following formulas:

wherein R is₁Is a linear alkyl group having 1 to 9 carbon atoms or an alkenyl group having 2 to 7 carbon atoms; x₁～X₆is-H or-CH₃And at least one is-CH₃。

Further, the structure of the liquid crystal compound is one of the following formulas:

wherein R is₁Is a linear alkyl group having 1 to 9 carbon atoms or an alkenyl group having 2 to 7 carbon atoms.

In addition, the invention provides a liquid crystal composition, which comprises 1-90% of a liquid crystal compound shown in a general formula (I), 1-60% of a liquid crystal compound shown in a general formula (II), and 0-50% of a liquid crystal compound shown in a general formula (III):

wherein ring A is cyclohexyl or cyclohexenyl; r ₁Is one of a C1-9 linear alkyl group, a linear alkoxy group, a linear fluoroalkyl group, or a C2-9 alkenyl group, an alkenyloxy group, or a difluorovinyl group; x₁～X₆is-H or-CH₃And at least one is-CH₃(ii) a m is 0 or 1;

wherein R is₂、R₃Each of which is a linear alkyl group, a linear alkoxy group, or a fluoroalkyl group having 1 to 9 carbon atoms, or an alkenyl group, an alkenyloxy group, or a difluorovinyl group having 2 to 9 carbon atoms; b is a single bond, an ethane bridge bond or a carbon-carbon triple bond; x₇～X₁₃is-H or-CH₃And at least one is-CH₃(ii) a n and p are 0 or 1.

Further, the liquid crystal compound represented by the general formula (II) is 10 to 50% and the liquid crystal compound represented by the general formula (III) is 5 to 40%.

Further, the present invention also provides a high-frequency device comprising any one or more of the liquid crystal compounds described above, or the liquid crystal composition described above.

In addition, the invention also provides a method for preparing the liquid crystal compound, which adopts the following synthetic route:

the method comprises the following steps:

s1, sequentially adding the raw material (1), calcium carbonate and water into a reaction bottle, adding elemental iodine at the temperature of-5 ℃, and reacting for 2 hours under heat preservation for post-treatment; filtering the reaction solution, extracting the filtrate with toluene, washing the filtrate to be neutral, drying the filtrate with anhydrous magnesium sulfate, filtering, performing rotary evaporation on the filtrate to remove the toluene, and adding a mixed solution of toluene and n-heptane for recrystallization to obtain an intermediate (2);

S2, under the protection of nitrogen, adding the intermediate (2), the raw material (3), bis (triphenylphosphine) palladium dichloride, TBAB and K into a reaction bottle₂CO₃Toluene, ethanol, water; carrying out reflux reaction for 4h, and then cooling to room temperature for post-treatment; standing and layering the reaction solution, adding toluene into the lower layer for extraction, combining organic phases, washing the organic phases to be neutral, drying the organic phases with anhydrous magnesium sulfate, filtering, and performing recrystallization after rotary evaporation of the filtrate to obtain an intermediate 5; or under the protection of nitrogen, adding the intermediate (2), the raw material (4), bis (triphenylphosphine) palladium dichloride, cuprous iodide, triphenylphosphine and triethylamine into a reaction bottle, reacting for 2 hours, and then carrying out aftertreatment; filtering the reaction solution, carrying out rotary evaporation on the filtrate to remove triethylamine, adding toluene to dissolve, washing with water to be neutral, drying with anhydrous magnesium sulfate, filtering, and carrying out recrystallization on the filtrate after rotary evaporation to obtain an intermediate (5);

s3, adding the intermediate (5), acetone and water into a three-necked bottle, dropwise adding thiophosgene at room temperature, reacting at room temperature for 1 hour after the thiophosgene is added, and monitoring by TLC to stop the reaction when no raw material remains; and (3) carrying out rotary evaporation, adding toluene to dissolve the obtained crude product, washing with water to neutrality, drying with anhydrous magnesium sulfate, filtering, carrying out rotary evaporation, dissolving with n-heptane, and carrying out column chromatography purification to obtain the target compound (6).

Further, in step S1, the molar ratio of the raw material (1), calcium carbonate and iodine is 1:1.3 (1-0.95), and the reaction temperature is-5-50 ℃; in the step S2, the molar ratio of the intermediate (2) to the raw material (3) is 1 (1-1.3), the temperature of the Suzuki coupling reaction is 0-90 ℃, and the intermediate (2) is bis (triphenylphosphine) palladium dichloride, TBAB: K₂CO₃The molar ratio of (1), (0.1% -3%) (0.1-0.5) to (1-5); or in the step S2, the molar ratio of the intermediate (2) to the raw material (4) is 1 (1-1.1), the Soniganshira coupling reaction temperature is 0-50 ℃, and the molar ratio of the intermediate (2) to bis (triphenylphosphine) dichloride to cuprous iodide to triphenylphosphine is 1 (0.1-3%) (0.3-9%); in step S3, the molar ratio of the intermediate (5) to the thiophosgene is 1 (1-2).

(III) advantageous effects

The invention provides a liquid crystal medium for high-frequency technology and a component thereof. The liquid crystal compound has the advantages of low melting point, low dielectric loss, high tuning rate and low rotational viscosity, and a nematic phase liquid crystal composition formed by adding the liquid crystal compound into mixed liquid crystal has low dielectric loss and high tuning rate, also has a wide nematic phase temperature range, low melting point and low rotational viscosity, can improve the performance of a high-frequency component when being used for the high-frequency component, and is particularly suitable for the fields of intelligent antenna liquid crystal phase shifters and 5G communication networks. The preparation method of the liquid crystal compound has the advantages of short synthesis steps, low raw material cost, easy operation of experimental process and simple post-treatment process.

Detailed Description

In order to make the objects, contents and advantages of the present invention clearer, the following detailed description of the embodiments of the present invention will be given in conjunction with examples.

GC in the examples represents gas chromatography purity (%), test instrument: an HP6820 gas chromatograph of Agilent;¹HNMR stands for nuclear magnetic resonance hydrogen spectrum, test instrument: advanced500MHz NMR spectrometer from Bruker; GC-MS represents the gas chromatograph-mass spectrometer, test instrument: agilent MS5975C model GC.

The physical property test method of the liquid crystal compound is as follows:

clearing spot (T)_ni): the polarizing hot stage method: and coating the liquid crystal sample on a glass slide, placing the glass slide in an orthogonal polarization microscopic hot table, setting the heating rate to be 3 ℃/min, and observing the temperature of the liquid crystal sample when the liquid crystal sample turns black from a bright state, namely the clearing point. Differential scanning calorimetry: under the protection of nitrogen, the heating rate is set to be 3 ℃/min.

The method for testing the physical properties of the liquid crystal compound under high frequency comprises the following steps: adding the mixed liquid crystal into a basic formula (Host) according to the mass ratio of 20%, and testing the dielectric anisotropy delta epsilon, the dielectric tuning rate tau and the dielectric loss (tan delta) of the mixed liquid crystal at 19GHz by adopting a vector network analyzer and a cavity perturbation method _∥,tanδ_⊥) And calculating to obtain the quality factor eta.

Example 1

Synthesis of 4-isothiocyanate-2-methyl-4 '- (4-propylcyclohexyl) -1,1' -biphenyl

The concrete structure is as follows:

the preparation process comprises the following steps:

step 1: synthesis of 4-iodo-3-methylaniline

M-methylaniline (60g,0.558mol), iodine (212.6g, 0.837mol) and 900ml of water were put into a 2L three-necked flask, and stirred at 50 ℃ for reaction for 4 hours. Cooling the reaction solution to room temperature, adding toluene for extraction for 3 times, combining organic phases, washing the organic phases to be neutral, and evaporating the solvent. Recrystallizing to obtain 68g of purple solid, namely 4-iodo-3-toluidine, with the purity of 99 percent and the yield of 52 percent.

Step 2: synthesis of 2-methyl-4 '- (4-propylcyclohexyl) - [1,1' -biphenyl ] -4-amine

The concrete structure is as follows:

to a reaction flask under nitrogen atmosphere were added (4- (4-propylcyclohexyl) phenyl) boronic acid (6.32g, 0.0256mol), 4-iodo-3-toluidine (4.59g,0.0197mol), potassium carbonate (13.6g, 0.0985mol), PdCl₂(PPh₃)₂(0.14g,0.2mmol), tetrabutylammonium bromide (0.64g, 2.0mmol), 45ml of toluene, 45ml of ethanol, and 45ml of water. And carrying out reflux reaction for 6h, and carrying out post-treatment. The reaction solution was extracted with toluene 3 times, the organic phases were combined, washed with water to neutrality, and dried over anhydrous magnesium sulfate. After the solvent is removed by rotary evaporation, the obtained crude product is recrystallized to obtain 2-methyl-4 '- (4-propylcyclohexyl) - [1,1' -biphenyl ]3.25g of (E) -4-amine, GC purity 99.6%, yield 82%.

And step 3: synthesis of 4-isothiocyanate-2-methyl-4 '- (4-propylcyclohexyl) -1,1' -biphenyl

2-methyl-4 '- (4-propylcyclohexyl) - [1,1' -biphenyl ] -4-amine (4.74g, 0.0154mol), thiophosgene (3.41g, 0.0308mol) and 50mL of chloroform were added to a reaction flask, and the reaction was stirred at 50 ℃ for 1 hour. And (3) cooling the reaction liquid to room temperature, separating an organic layer, adding chloroform into a water layer for extraction, combining organic phases, washing the organic phases to be neutral, and drying the organic phases with anhydrous magnesium sulfate. Filtering, evaporating filtrate to dryness, purifying crude product by column chromatography, and recrystallizing to obtain white solid 3.09g with purity of 99.79% and yield of 84%.

And (3) structural identification:

¹H NMR(δ,CDCl₃):0.933–0.962(t,3H),1.067–1.148(m,2H), 1.242–1.285(m,2H),1.313–1.435(m,3H),1.505–1.559(m,2H), 1.906–1.985(m,4H),2.514–2.575(m,1H),2.293(s,3H),7.103–7.123 (q,1H),7.161–7.165(d,J＝2Hz,1H),7.214–7.230(m,3H),7.275–7.291 (t,2H)。

the above structural identification data indicate that the synthesized compound is indeed 4-isothiocyanate-2-methyl-4 '- (4-propylcyclohexyl) -1,1' -biphenyl.

The phase transition temperature of 4-isothiocyanate-2-methyl-4 '- (4-propylcyclohexyl) -1,1' -biphenyl was measured by DSC at a temperature rise of 3 ℃/min and found to be: cr 79.11N 102.02I, melting point 79.10 deg.C, this compound has a lower melting point.

Example 2

Synthesis of 4-isothiocyanate-2-methyl-4 '- (4-ethylcyclohexyl) -1,1' -biphenyl

The concrete structure is as follows:

4-isothiocyanate-2-methyl-4 '- (4-ethylcyclohexyl) -1,1' -biphenyl was synthesized in the same manner as in example 1, using (4- (4-hexylcyclohexyl) phenyl) boronic acid instead of (4- (4-propylcyclohexyl) phenyl) boronic acid in step (2) of example 1.

Example 3

Synthesis of 4'- (4-butylcyclohexyl) -4-isothiocyanate-2-methyl-1, 1' -biphenyl

The concrete structure is as follows:

4'- (4-butylcyclohexyl) -4-isothiocyanate-2-methyl-1, 1' -biphenyl was synthesized in the same manner as in example 1, using (4- (4-butylcyclohexyl) phenyl) boronic acid instead of (4- (4-propylcyclohexyl) phenyl) boronic acid in step (2) of example 1, with a purity of 99.26% and a yield of 80%.

And (3) structural identification:

¹H NMR(CDCl₃,500MHz)δ(ppm):0.934–0.962(t,3H),1.071– 1.150(m,2H),1.275–1.299(m,2H),1.343–1.384(m,5H),1.504–1.561(m,2H),1.914–1.987(m,4H),2.293(s,3H),2.515–2.577(m, 1H),7.103–7.123(q,1H),7.161–7.165(d,1H),7.214–7.234(m,3H), 7.275–7.291(t,2H)。

the above structural identification data indicate that the synthesized compound is indeed 4'- (4-butylcyclohexyl) -4-isothiocyanate-2-methyl-1, 1' -biphenyl.

The liquid crystal phase transition temperature of 4'- (4-butylcyclohexyl) -4-isothiocyanate-2-methyl-1, 1' -biphenyl was measured by DSC at a temperature rise of 3 ℃/min and found to be: cr 62.29N 101.22I, melting point 62.29 ℃, the compound has a lower melting point.

Example 4

Synthesis of 4-isothiocyanate-2-methyl-4 '- (4-pentylcyclohexyl) -1,1' -biphenyl

The concrete structure is as follows:

4-isothiocyanate-2-methyl-4 '- (4-pentylcyclohexyl) -1,1' -biphenyl was synthesized in the same manner as in example 1, using (4- (4-pentylcyclohexyl) phenyl) boronic acid instead of (4- (4-propylcyclohexyl) phenyl) boronic acid in step (2) of example 1, and the purity was 99.79%.

And (3) structural identification:

¹H NMR(CDCl₃,500MHz)δ(ppm):0.931-0.959(t,3H), 1.073-1.154(m,2H),1.269-1.381(m,9H),1.509-1.576(m,2H), 1.917-1.991(m,4H),2.297(s,3H),2.519-2.581(m,1H),7.105-7.125(q, 1H),7.164-7.168(d,1H),7.219-7.234(m,3H),7.279-7.304(t,2H)。

the liquid crystal phase transition temperature of 4-isothiocyanate-2-methyl-4 '- (4-pentylcyclohexyl) -1,1' -biphenyl was measured by DSC at a temperature rise of 3 ℃/min and found to be: the thermal performance data is Cr 66.67N 120.39I, the melting point is 66.67 ℃, and the compound has a lower melting point.

The monomer liquid crystal is added into the basic formula Host in a mass percent of 20% to form a mixed liquid crystal, and the physical properties of the formula at 19GHz are tested at 20 ℃ and the data are shown in Table 1.

TABLE 1 test data

Mixed crystal code	ε⊥	ε∥	△ε	tanδ⊥	tanδ∥	τ	η
								Host	2.599	3.566	0.967	0.0230	0.0101	0.271	12.2
Example 4+ Host	2.535	3.409	0.874	0.0178	0.0083	0.250	14.1

After the compound of example 4 was added, the loss tangent in the vertical direction of the liquid crystal molecules at 18.2GHz of the mixed liquid crystal was reduced by 23% and the quality factor was increased by 16%. The compound proved to have the advantages of low dielectric loss and high quality factor.

Example 5

Synthesis of 4-isothiocyanate-3-methyl-4 '- (4-pentylcyclohexyl) -1,1' -biphenyl

The concrete structure is as follows:

4-isothiocyanate-3-methyl-4 '- (4-pentylcyclohexyl) -1,1' -biphenyl was synthesized in the same manner as in example 1, using (4- (4-pentylcyclohexyl) phenyl) boronic acid instead of (4- (4-propylcyclohexyl) phenyl) boronic acid in step (2) of example 1 and 4-iodo-2-methylaniline instead of 4-iodo-3-methylaniline in step (2) of example 1.

The phase transition temperature of 4-isothiocyanate-2-methyl-4 '- (4-propylcyclohexyl) -1,1' -biphenyl was measured by DSC at a temperature rise of 3 ℃/min and found to be: cr 92.66N 170.04I, a melting point of 92.66 ℃, has a very high clearing point (170.04 ℃) and a wide nematic phase temperature range (77.38 ℃).

Example 6

Synthesis of 4-isothiocyanate-2-methyl-1- ((4- (4-pentylcyclohexyl)) phenyl) ethynyl) benzene

The concrete structure is as follows:

the preparation process comprises the following steps:

step 1: synthesis of 3-methyl-4- ((4- (4-pentylcyclohexyl) phenyl) ethynyl) amine

Under the protection of nitrogen, 4-iodo-3-methylaniline (6.28g, 0.0269mol), PdCl were added to the reaction flask₂(PPh₃)₄(0.56g,0.8mmol), cuprous iodide (0.46g, 2.4mmol), triphenylphosphine (0.63g,2.4mmol), and triethylamine 60 ml. After stirring and controlling the temperature at 50 ℃, a mixed solution of 1-ethynyl-4- (4-pentylcyclohexyl) benzene (7.12g,0.028mol) and 60ml triethylamine was added dropwise, and after the addition, the reaction was carried out for 2.5 hours for post-treatment. And filtering the reaction solution, selectively evaporating the filtrate to dryness, adding toluene, washing with water to neutrality, drying with anhydrous magnesium sulfate, filtering, and rotatably evaporating the filtrate to dryness, and recrystallizing the obtained crude product with toluene to obtain light yellow solid 7.93g, wherein the GC purity is 99.17%, and the yield is 82%.

Step 2: preparation of 4-isothiocyanato-2-methyl-1- ((4- (4-pentylcyclohexyl)) phenyl) ethynyl) benzene

The specific structural formula is as follows:

4-isothiocyanate-2-methyl-1- ((4- (4-pentylcyclohexyl)) phenyl) ethynyl) benzene was synthesized in the same manner as in example 1 using 3-methyl-4- ((4- (4-pentylcyclohexyl) phenyl) ethynyl) amine in place of 2-methyl-4 '- (4-propylcyclohexyl) - [1,1' -biphenyl ] -4-amine in step (3) of example 1, with a purity of 99.93% and a yield of 81%.

And (3) structural identification:

¹H NMR(CDCl₃,500MHz)δ(ppm):0.919-0.947(t,3H), 1.041-1.123(m,2H),1.235-1.360(m,10H),1.432-1.510(m,2H), 1.904-1.923(m,4H),2.505(s,3H),7.037-7.057(q,1H),7.120-7.123(d, 1H),7.221-7.237(d,J＝8Hz,2H),7.458-7.493(q,3H)。

the above structural identification data indicates that the synthesized compound is indeed 4-isothiocyanate-2-methyl-1- ((4- (4-pentylcyclohexyl)) phenyl) ethynyl) benzene.

The liquid crystal phase transition temperature of 4-isothiocyanate-2-methyl-1- ((4- (4-pentylcyclohexyl)) phenyl) ethynyl) benzene was measured by DSC at a temperature rise of 3 ℃/min and was: cr 64.54N 215.27I, melting point 64.54 deg.C, clearing point 215.27 deg.C, nematic phase temperature range 150.73 deg.C, and the compound has low melting point, very high clearing point and very wide nematic phase temperature range.

The monomer liquid crystal is added into the basic formula Host in a mass percent of 20% to form a mixed liquid crystal, and the physical properties of the formula at 19GHz are tested at 20 ℃ and the data are shown in Table 2.

TABLE 2 test data

Mixed crystal code	ε⊥	ε∥	△ε	tanδ⊥	tanδ∥	τ	η
								Host	2.599	3.566	0.967	0.0230	0.0101	0.271	12.2
Example 6+ Host	2.505	3.51	1.005	0.0181	0.0079	0.286	15.8

After the compound of example 6 was added, the dielectric anisotropy value at 18.2GHz of the mixed liquid crystal was increased by 4%, the loss tangent in the vertical direction of the liquid crystal molecules was decreased by 21%, the tuning rate was increased by 5%, and the quality factor was increased by 30%. The compound is proved to have the advantages of high dielectric tuning rate, low dielectric loss and high quality factor.

Example 7

Synthesis of 1- ((4- (4-ethylcyclohexyl) phenyl) ethynyl) -4-isothiocyanate-2-methylbenzene

The concrete structure is as follows:

1- ((4- (4-ethylcyclohexyl) phenyl) ethynyl) -4-isothiocyanate-2-methylbenzene was synthesized in the same manner as in example 6, using 1-ethynyl-4- (4-pentylcyclohexyl) benzene instead of 1-ethynyl-4- (4-pentylcyclohexyl) benzene in step (1) of example 6.

Example 8

Synthesis of 4-isothiocyanato-2-methyl-1- ((4- (4-propylcyclohexyl) phenyl) ethynyl) -benzene

The concrete structure is as follows:

4-Isothiocyanate-2-methyl-1- ((4- (4-propylcyclohexyl) phenyl) ethynyl) -benzene was synthesized in the same manner as in example 6, using 1-ethynyl-4- (4-pentylcyclohexyl) benzene instead of 1-ethynyl-4- (4-pentylcyclohexyl) benzene in step (1) of example 6.

Example 9

Synthesis of 4-isothiocyanato-2-methyl-1- ((4- (4-butylcyclohexyl) phenyl) ethynyl) -benzene

The concrete structure is as follows:

4-Isothiocyanate-2-methyl-1- ((4- (4-butylcyclohexyl) phenyl) ethynyl) -benzene was synthesized in the same manner as in example 6, using 1-ethynyl-4- (4-butylcyclohexyl) benzene instead of 1-ethynyl-4- (4-pentylcyclohexyl) benzene in step (1) of example 6, with a purity of 99.98%.

The liquid crystal phase transition temperature of 4-isothiocyanate-2-methyl-1- ((4- (4-pentylcyclohexyl)) phenyl) ethynyl) benzene was measured by DSC at a temperature rise of 3 ℃/min and was: cr 67.72N 219.72I, the melting point is 67.72 ℃, the clearing point is up to 219.72 ℃, the temperature range of the nematic phase is 152 ℃, and the compound has a lower melting point, a very high clearing point and a very wide temperature range of the nematic phase.

Example 10

Synthesis of 4'- ((4-isothiocyanato-2-methylphenyl) ethynyl) -4-pentyl-2, 3,4, 5-tetrahydro-1, 1' -biphenyl

The concrete structure is as follows:

4'- ((4-isothiocyanate-2-methylphenyl) ethynyl) -4-pentyl-2, 3,4, 5-tetrahydro-1, 1' -biphenyl was synthesized in the same manner as in example 1, using (4 '-pentyl-2', 3',4',5 '-tetrahydro- [1,1' -biphenyl ]) acetylene instead of (4- (4-propylcyclohexyl) phenyl) boronic acid in step (2) of example 1.

The liquid crystal phase transition temperature of 4'- ((4-isothiocyanato-2-methylphenyl) ethynyl) -4-pentyl-2, 3,4, 5-tetrahydro-1, 1' -biphenyl was measured at a temperature rise of 3 ℃/min and the results were: cr 78.09N 204.72I, the melting point is 78.09 ℃, the clearing point is 204.72 ℃, the nematic phase temperature range is 126.63 ℃, and the compound has a lower melting point, a very high clearing point and a very wide nematic phase temperature range.

Example 11

Synthesis of 4' -isothiocyanate-2 ' -methyl-4-pentyl-2, 3,4, 5-tetrahydro-1, 1':4', 1' -terphenyl

The concrete structure is as follows:

4' -isothiocyanate-2 ' -methyl-4-pentyl-2, 3,4, 5-tetrahydro-1, 1':4', 1' -terphenyl was synthesized in the same manner as in example 1 using (4' -pentyl-2 ',3',4',5' -tetrahydro- [1,1' -biphenyl ]) boronic acid instead of (4- (4-propylcyclohexyl) phenyl) boronic acid in step (2) of example 1.

Example 12

Liquid crystal compositions containing the structures of examples 1, 3,4, 9 (see table 3) comprise the following components: wherein "%" represents "mass percent", the measurement characteristics in examples are as follows: Δ n: birefringence anisotropy at 589 nm; t is_ni: clearing the bright spots; k₁₁: a splay elastic constant; k₃₃: a torsional elastic constant; Δ ε: a dielectric anisotropy; gamma ray ₁: rotational viscosity.

TABLE 3 example 12 composition and Properties

As can be seen from the data in the table above: the clearing point of example 12 is 108.21 ℃, the low temperature nematic phase temperature can reach-40 ℃; the rotational viscosity is less than 700 mPas. The dielectric loss under 18.2GHz is lower than 0.007, the tuning rate can reach 0.29, and the quality factor is as high as 45.3. The liquid crystal composition of the embodiment has particularly good low-temperature compatibility and particularly wide nematic phase temperature range, and also has particularly low dielectric loss and very high quality factor and lower rotational viscosity, and further proves the advantages of the composition.

Comparative example 1

Synthesizing a fluorine-containing isothiocyanate liquid crystal compound 5- ((4- (4-butylcyclohexyl) phenyl) ethynyl) -1, 3-difluoro-2-isothiocyanate according to a literature method, wherein the structure is shown as the following formula:

the liquid crystal phase transition temperature of 5- ((4- (4-butylcyclohexyl) phenyl) ethynyl) -1, 3-difluoro-2-isothiocyanate was measured at a temperature rise of 3 ℃/min, and the results were: cr 75.12N 216.79I, melting point 75.12 deg.C, clearing point 216.79 deg.C, and nematic phase temperature range 141.67 deg.C.

The monomer liquid crystal was added to the base formulation Host at 20% by mass to form a mixed liquid crystal, and the physical properties of the formulation at 19GHz were measured at 20 ℃ and the data are shown in Table 4.

TABLE 4 test data

Mixed crystal code	ε⊥	ε∥	△ε	tanδ⊥	tanδ∥	τ	η
								Host	2.599	3.566	0.967	0.0232	0.0101	0.271	12.2
Comparative example 1+ Host	2.509	3.501	0.992	0.0188	0.0084	0.283	15.1

After the compound of comparative example 1 was added, the loss tangent of the mixed liquid crystal in the long axis direction of the liquid crystal molecules was reduced to 0.0188 at a high frequency, and the quality factor was increased to 15.1. The compound of example 6 has the following structure:

the thermal performance data is Cr 64.54N 215.27I; comparing the thermal properties of the compound of example 6 and the compound of comparative example 1, it can be seen that the melting point of the compound of example 6 is reduced by 10.58 c compared to the melting point of the compound of comparative example 1.

The monomeric liquid crystal of comparative example 1 was added to the base formulation Host at a mass percent of 20% to form a mixed liquid crystal, and the physical properties of the formulation at 19GHz were tested at 20 ℃ and the data are shown in Table 5.

TABLE 5 test data

Mixed crystal code	ε⊥	ε∥	△ε	tanδ⊥	tanδ∥	τ	η
								Host	2.599	3.566	0.967	0.0230	0.0101	0.271	12.2
Example 6+ Host	2.505	3.51	1.005	0.0181	0.0079	0.286	15.8

Comparing the data in tables 4 and 5, it can be seen that the compound of example 6 has the advantages of lower dielectric loss, higher dielectric tuning rate and higher quality factor.

Comparative example 2

The fluorine-containing isothiocyanate liquid crystal compound 3, 5-difluoro-4-isothiocyanate-4 '- (4-pentylcyclohexyl) -1,1' -biphenyl is synthesized according to a literature method, and has the structure shown as the following formula:

the monomeric liquid crystal of comparative example 2 was added to the base formulation Host at a mass percent of 20% to form a mixed liquid crystal, and the physical properties of the formulation at 19GHz were tested at 20 ℃ and the data are shown in Table 6.

TABLE 6 test data

Mixed crystal code	ε⊥	ε∥	△ε	tanδ⊥	tanδ∥	τ	η
								Host	2.599	3.566	0.967	0.0232	0.0101	0.271	12.2
Comparative example 2+ Host	2.563	3.484	0.921	0.0200	0.0093	0.264	13.2

After the compound of comparative example 2 was added, the loss tangent of the mixed liquid crystal in the long axis direction of the liquid crystal molecules was reduced to 0.02 at a high frequency, and the quality factor was increased to 13.2. The compound of example 4 has the following structure:

the monomer liquid crystal is added into a basic formula Host by mass percent of 20% to form a mixed liquid crystal, and the physical properties of the formula at 19GHz are tested at 20 ℃, wherein the loss angle of the liquid crystal molecules in the vertical direction is reduced to 0.0178, and the quality factor is increased to 14.1. The compound is proved to have the advantages of lower dielectric loss and higher quality factor.

Comparative example 3

Liquid crystal compositions containing lateral fluorine substituents of the same backbone structure as in the composition of example 12 (see table 7) comprise the following ingredients: wherein "%" represents "mass percent", the measurement characteristics in examples are as follows: Δ n: birefringence anisotropy at 589 nm; t is_ni: clearing the bright spots; k₁₁: a splay elastic constant; k₃₃: a torsional elastic constant; Δ ε: a dielectric anisotropy; gamma ray₁: rotational viscosity.

TABLE 7 comparative example 3 composition and Properties

Comparing the data in table 3 and table 7 shows that: example 12 has a lower low temperature nematic temperature, and remains nematic at-40 ℃; compared with the comparative example 3, the dielectric loss of the example 12 at 19GHz is reduced by 52%, the tuning rate is improved by 10%, and the quality factor is increased by 2.2 times. It can be seen that the composition of example 12 not only has better low temperature compatibility, but also has lower dielectric loss, higher tuning rate and higher quality factor, further proving the advantages of the composition.

Comparative example 4

The measured properties of example 4, i.e. the formulation and properties consisting of fluorine-containing NCS liquid crystal monomers, reported in Merck patent 201510482208.6, in the comparative example are as follows: Δ n: birefringence anisotropy at 589 nm; t is_ni: clearing the bright spots; k₁₁: a splay elastic constant; k₃₃: a torsional elastic constant; Δ ε: a dielectric anisotropy; gamma ray₁: rotational viscosity. See table 8 for details.

TABLE 8 COMPARATIVE EXAMPLE 4 formulation and Properties

Comparing the data in table 3 and table 8 shows that: compared with comparative example 4, the dielectric loss of example 12 at 19GHz is reduced by 65%, and the quality factor is increased by 2.7 times. It can be seen that the composition of example 12 has lower dielectric loss and higher quality factor, further demonstrating the advantages of the composition.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.