Disclosure of Invention
The invention aims to provide a liquid crystal compound which has low delta n, low rotational viscosity gamma 1, larger negative dielectric anisotropy delta epsilon, good liquid crystal intersolubility and higher clearing point Cp, thereby effectively improving the clearing point of a liquid crystal composition, shortening the response time of a liquid crystal display device and improving the working temperature of the liquid crystal composition.
The structural formula of the liquid crystal compound provided by the invention is shown as the formula I:
in the formula I, R1And R2The substituents are the same or different, and each independently represent a substituted or unsubstituted C1-C12 linear or branched alkyl group, C3-C7 cycloalkyl or cycloalkenyl group, C2-C12 linear or branched alkenyl group, C2-C7 linear or branched alkynyl group, C2-C12 ester group or C2-C12 ether group;
R1and R2The substituent in (1) is halogen, preferably fluorine;
preferably, R1And R2Independently represent a linear or branched alkyl group of C1-C7, a cycloalkyl group of C3-C6, a linear or branched alkenyl group of C2-C7, an ester group of C2-C7 or an ether group of C2-C7, more preferably a linear or branched alkyl group of C1-C7, a cycloalkyl group of C3-C6, a linear or branched alkenyl group of C2-C7 or an ether group of C2-C7;
L1and L2The same or different, each independently represent-F, -Cl, -CN, -NO2Straight chain or branched chain alkyl of C1-C10, alkoxy of C1-C5, -COR1、-COR2A fluoroalkyl group having 1-5 carbon atoms or a fluoroalkoxy group having 1-5 carbon atoms, wherein R is1Is C1-C5 alkyl, R2Is C1-C5 alkyl;
preferably, L1And L2Wherein the carbon atom number of the straight chain or branched chain alkyl is 1-5;
the carbon number of the alkoxy is 1-3;
R1is C1-C3 alkyl;
R2is C1-C3 alkyl;
the fluoroalkyl group has 1-3 carbon atoms and contains one or more fluorine atoms;
the carbon number of the fluoroalkoxy group is 1-3, and the fluoroalkoxy group contains one or more fluorine atoms;
more preferably, L1And L2Independently represent-F, -Cl, -CN, -CF3or-OCF3Further, L1And L2Both represent-F;
Z1and Z2The same or different, each independently represents O or S, and is not simultaneously O.
The liquid crystal compound provided by the invention is preferably one of the following structures:
the invention further provides a preparation method of the liquid crystal compound, and the reaction equation is as follows:
the reaction steps are as follows:
s1, reacting the compound shown as the formula II with X in the presence of tert-butyl lithium in an inert atmosphere12Obtaining a compound shown as a formula III through halogenation, wherein X1Represents Br or I;
s2, a compound of formula III and R2-Z2Carrying out etherification reaction on the-H to obtain the liquid crystal compound;
R1、R2、Z1、Z2、L1、L2the definition of (a) is the same as that of the liquid crystal compound shown in the formula I.
In the preparation method, in step S1, the n-hexane solution of the tert-butyl lithium is dripped into the system at the temperature of-70 to-80 ℃, the temperature is kept for 1 to 2 hours after dripping, and then X is continuously dripped12Controlling the temperature to be-70 to-80 ℃ for reaction for 1 hour, naturally returning the temperature to-30 to-10 ℃, and carrying out hydrolysis post-treatment;
a compound of formula II and X12In a molar ratio of 1: 1.0 to 1.5.
In the above preparation method, in step S2, the etherification reaction is performed under an inert atmosphere, and the solvent may be dioxane;
a compound of the formula III with R2-Z2-the molar ratio of H is 1: 1.0 to 1.5;
the etherification reaction is carried out in the presence of alkali, wherein the alkali can be sodium hydroxide, potassium hydroxide, anhydrous potassium carbonate or anhydrous sodium carbonate;
the temperature of the etherification reaction is 70-90 ℃, and the time is 3-8 hours.
The starting materials (formulae II and R) used in the process of the invention2-Z2-H) are commercially available.
The present invention still further provides a liquid crystal compound comprising the liquid crystal composition;
in the liquid crystal composition, the mass percent of the liquid crystal compound is 1-60%, preferably 1-50%, and more preferably 1-25%.
The application of the liquid crystal compound or the liquid crystal composition provided by the invention in the preparation of a liquid crystal display device also belongs to the protection range of the method;
the liquid crystal display device is a TN liquid crystal display, an ADS liquid crystal display, a VA liquid crystal display, a PSVA liquid crystal display, an FFS liquid crystal display or an IPS liquid crystal display.
The liquid crystal compound provided by the invention has very low delta n, very low rotational viscosity gamma 1, larger negative dielectric anisotropy delta epsilon, good liquid crystal intersolubility and higher clearing point Cp, thereby effectively improving the clearing point of the liquid crystal composition, shortening the response time of a liquid crystal display device and improving the working temperature of the liquid crystal composition.
Detailed Description
The experimental procedures used in the following examples are all conventional procedures unless otherwise specified.
Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.
The ethers used in the following examples are all available from Yongtai technologies, Zhejiang.
Example 1 preparation of liquid Crystal Compound BYLC-01
The liquid crystal compound BYLC-01 prepared in the embodiment has the structural formula:
the synthetic route for the preparation of compound BYLC-01 is shown below:
the method comprises the following specific steps:
(1) synthesis of Compound BYLC-01-1:
under the protection of nitrogen, 50.0g of 2, 3-difluorophenylbutyl ether and 400ml of tetrahydrofuran are added into a reaction bottle, the temperature is controlled to be-70 to-80 ℃, 0.4mol of n-hexane solution of tert-butyllithium is dripped, the reaction is kept for 1 hour after dripping is finished, 64.5g of bromine is dripped at the temperature of-70 to-80 ℃ (the molar ratio of the 2, 3-difluorophenylbutyl ether to the bromine is 1: 1.5), and then the temperature is naturally returned to-30 ℃. 500ml of a saturated aqueous sodium sulfite solution was added for hydrolysis destruction, and conventional post-treatment was carried out, and distillation under reduced pressure was carried out to obtain 60.9g of a pale yellow liquid (compound BYLC-01-1), GC: 99.2% and yield 85.5%.
(2) Synthesis of Compound BYLC-01:
under the protection of nitrogen, 60.0g of compound BYLC-01-1, 18.2g of ethanethiol (the molar ratio of the compound BYLC-01-1 to the ethanethiol is 1: 1.29), 13.5g of sodium hydroxide and 200ml of dioxane are added into a reaction flask, and the temperature is controlled between 70 ℃ and 90 ℃ for reaction for 6 hours. Conventional work-up was carried out, purification by chromatography, elution with n-hexane and crystallization with ethanol gave 40.5g of a white solid (compound BYLC-01), GC: 99.7%, yield: 72.8 percent.
The obtained white solid BYLC-01 was analyzed by GC-MS and the M/z of the product was 246.3 (M)+)。
1H-NMR(300MHz,CDCl3):0.85-1.95(m,10H),2.51-2.95(m,2H),3.53-4.75(m,2H),6.55-7.75(m,2H)。
Example 2 preparation of liquid crystalline Compound BYLC-02
The liquid crystal compound prepared in this example has the structural formula:
the synthetic route for the preparation of compound BYLC-02 is shown below:
the method comprises the following specific steps:
synthesis of Compound BYLC-02:
under the protection of nitrogen, 33.0g of compound BYLC-01-1, 15.6g of butyl mercaptan (the molar ratio of compound BYLC-01-1 to butyl mercaptan is 1: 1.38), 7.5g of sodium hydroxide and 150ml of dioxane are added into a reaction flask, and the temperature is controlled at 70-90 ℃ for reaction for 6 hours. Conventional work-up was carried out, purification by chromatography, elution with n-hexane and crystallization with ethanol gave 25.7g of a white solid (compound BYLC-02), GC: 99.8%, yield: 75.6 percent.
The obtained white solid BYLC-02 was analyzed by GC-MS and the M/z of the product was 274.1 (M)+)。
1H-NMR(300MHz,CDCl3):0.85-1.85(m,14H),2.67-2.95(m,2H),3.85-4.35(m,2H),6.55-7.45(m,2H)。
According to the technical schemes of the embodiment 1 and the embodiment 2, the following liquid crystal compounds can be synthesized by simply replacing corresponding raw materials without changing any substantial operation:
examples 3,
The resulting white solid BYLC-03 was analyzed by GC-MS and the M/z of the product was 246.1(M +).
1H-NMR(300MHz,CDCl3):0.85-1.85(m,10H),2.67-2.95(m,2H),3.85-4.35(m,2H),6.55-7.45(m,2H)。
Examples 4,
The obtained white solid BYLC-04 was analyzed by GC-MS and the M/z of the product was 260.1 (M)+)。
1H-NMR(300MHz,CDCl3):0.85-1.85(m,12H),2.67-2.95(m,2H),3.85-4.35(m,2H),6.55-7.45(m,2H)。
Examples 5,
The obtained white solid BYLC-05 was analyzed by GC-MS and the M/z of the product was 262.1 (M)+)。
1H-NMR(300MHz,CDCl3):0.85-1.85(m,10H),2.67-2.95(m,4H),6.55-7.45(m,2H)。
Examples 6,
The obtained white solid BYLC-06 was analyzed by GC-MS and the M/z of the product was 290.1 (M)+)。
1H-NMR(300MHz,CDCl3):0.85-1.85(m,14H),2.67-2.95(m,4H),6.55-7.45(m,2H)。
Example 7,
The obtained white solid BYLC-07 was analyzed by GC-MS and the M/z of the product was 248.1 (M)+)。
1H-NMR(300MHz,CDCl3):0.85-1.85(m,8H),2.67-2.95(m,4H),6.55-7.45(m,2H)。
Example 8,
The obtained white solid BYLC-08 was analyzed by GC-MS and the M/z of the product was 298.1 (M)+)。
1H-NMR(300MHz,CDCl3):0.15-0.85(m,5H),1.15-1.95(m,9H),2.67-2.95(m,2H),3.85-4.25(m,2H),6.55-7.45(m,2H)。
Examples 9,
The obtained white solid BYLC-09 was analyzed by GC-MS and the M/z of the product was 272.1 (M)+)。
1H-NMR(300MHz,CDCl3):1.15-1.85(m,10H),1.95-2.95(m,3H),3.85-4.25(m,2H),6.55-7.45(m,2H)。
Examples 10,
The obtained white solid BYLC-10 was analyzed by GC-MS and the M/z of the product was 286.1 (M)+)。
1H-NMR(300MHz,CDCl3):0.90-1.85(m,14H),2.55-2.95(m,2H),3.85-4.25(m,2H),6.55-7.45(m,2H)。
Examples 11,
The resulting white solid BYLC-11 was analyzed by GC-MS and the M/z of the product was 316.1(M +).
1H-NMR(300MHz,CDCl3):0.90-1.85(m,16H),2.55-2.95(m,4H),6.55-7.45(m,2H)。
Examples 12,
The obtained white solid BYLC-12 was analyzed by GC-MS and the M/z of the product was 258.1 (M)+)。
1H-NMR(300MHz,CDCl3):1.05-1.85(m,11H),2.25-2.75(m,1H),3.85-4.25(m,2H),6.55-7.45(m,2H)。
Examples 13,
The obtained white solid BYLC-13 was analyzed by GC-MS and the M/z of the product was 288.1 (M)+)。
1H-NMR(300MHz,CDCl3):0.90-1.95(m,13H),2.25-2.95(m,3H),6.55-7.45(m,2H)。
Comparative examples 1,
The structure of the compound of this comparative example is:
comparative examples 2,
The structure of the compound of this comparative example is:
the compounds prepared in the above examples of the invention and the compounds of the comparative examples were subjected to the relevant property measurements:
according to conventional detection methods in the art, for example, detection of Δ ε is measured using an INSTEC liquid crystal detection instrument, detection of γ 1 is measured using a viscometer, detection of Δ n is measured using an Abbe refractometer, and detection of Cp is measured using a differential thermal scanner.
And obtaining various performance parameters of the liquid crystal compound through linear fitting, wherein the specific meanings of the performance parameters are as follows:
Δ n represents optical anisotropy (25 ℃); Δ ε represents the dielectric anisotropy (25 ℃, 1000 Hz); γ 1 represents rotational viscosity (mpa.s, 25 ℃); cp stands for clearing point.
The data of the performance parameters of the compound prepared in the example and the liquid crystal compound of the comparative example are compared and the detection results are shown in table 1.
TABLE 1 results of examining the properties of the liquid-crystalline compounds
As is apparent from the detection results in table 1, compared with the conventional negative dielectric anisotropy compound with a similar chemical structure, the liquid crystal compound provided by the present invention has a very low Δ n, a very low rotational viscosity γ 1, a relatively large negative dielectric anisotropy Δ ∈ and a relatively high clearing point Cp, so that the clearing point of the liquid crystal composition is effectively increased, the response time of the liquid crystal display device is shortened, and the operating temperature of the liquid crystal composition is increased.
Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.