CN104003852B - A kind ofly contain three or the liquid crystalline cpd of quaterphenyl structure and application thereof - Google Patents

Abstract

The present invention provides a liquid crystal compound containing triphenyl or quaterphenyl structure, said liquid crystal compound has the structure shown in formula I: RA ₁ -A ₂ -A ₃ -A ₄ -O(CH ₂ )nF(I) the The compound has the characteristics of large optical anisotropy and stable structure, can further improve the optical anisotropy of the existing conventional liquid crystal composition after being applied to the liquid crystal composition, and has the technical effect of realizing rapid response.

Description

A kind of liquid crystal compound containing three or four biphenyl structures and application thereof

technical field

The invention relates to the field of liquid crystal display materials, in particular to a liquid crystal compound containing a triphenyl or quadruphenyl structure and an application thereof.

Background technique

At present, liquid crystals are widely used in the field of information display, and at the same time, some progress has been made in the application in optical communication (S.T.Wu, D.K.Yang. Reflective Liquid Crystal Displays. Wiley, 2001). In recent years, the application fields of liquid crystal compounds have been significantly expanded to various display devices, electro-optic devices, electronic components, sensors, etc. For this reason, many different structures have been proposed, especially in the field of nematic liquid crystals, and nematic liquid crystal compounds have been most widely used in flat panel displays so far. Especially for TFT active matrix systems.

Liquid crystal display has experienced a long development path with the discovery of liquid crystal. In 1888, Austrian botanist Friedrich Reinitzer discovered the first liquid crystal material, benzoic acid cholesterol (cholesterylbenzoate). In 1917, Manguin invented the rubbing orientation method to make monodomain liquid crystals and study optical anisotropy. In 1909, E.Bose established the theory of Swarm, which was supported by the experiments of L.S.Ormstein and F.Zernike (1918), and was later discussed as statistical fluctuation by DeGennes. G.W.Oseen and H.Zocher founded the continuum theory in 1933, and it was perfected by F.C.Frank (1958). M.Born (1916) and K.Lichtennecker (1926) discovered and studied the dielectric anisotropy of liquid crystals. In 1932, W.Kast divided the nematic phase into two categories, positive and negative. In 1927, V.Freedericksz and V.Zolinao discovered that the nematic liquid crystal was deformed and had a voltage threshold (Freederichsz transition) under the action of an electric field (or magnetic field). This finding provides a basis for the production of liquid crystal displays.

In 1968, R.Williams of RCA Company in the United States discovered that the nematic liquid crystal forms stripe domains under the action of an electric field, and has light scattering phenomenon. G.H.Heilmeir then developed it into a dynamic scattering display mode and made it the world's first liquid crystal display (LCD). In the early 1970s, Helfrich and Schadt invented the TN principle. People combined the TN photoelectric effect with integrated circuits to make it into a display device (TN-LCD), which opened up broad prospects for the application of liquid crystals. Since the 1970s, due to the development of large-scale integrated circuits and liquid crystal materials, the application of liquid crystals in display has achieved breakthrough development. From 1983 to 1985, T. Scheffer and others successively proposed super twisted nematic (SuperTwisredNematic: STN) Mode and the active matrix (Activematrix: AM) method proposed by P.Brody in 1972 are adopted again. The traditional TN-LCD technology has been developed into STN-LCD and TFT-LCD technology. Although the number of scanning lines of STN can reach more than 768 lines, there are still problems such as response speed, viewing angle and gray scale when the temperature rises. Therefore, Large area, high information content,

Most color displays use active matrix display. TFT-LCD has been widely used in direct-view TV, large-screen projection TV, computer terminal display and some military instrument display. It is believed that TFT-LCD technology has a broader application prospect.

The "active matrix" includes two types: 1. OMS (Metal Oxide Semiconductor) or other diodes on a silicon wafer as a substrate. 2. A thin film transistor (TFT) on a glass plate as a substrate.

Monocrystalline silicon as a substrate material limits the size of the display, because there are many problems in the combination of various display devices and even module assembly. Thus, the second thin-film transistor is a promising active-matrix type, where the photoelectric effect used is usually the TN effect. TFTs include compound semiconductors, such as Cdse, or TFTs based on polycrystalline or amorphous silicon.

At present, the technology of TFT-LCD products has matured and successfully solved technical problems such as viewing angle, resolution, color saturation and brightness, and its display performance has approached or surpassed that of CRT displays. Large size and small and medium size TFT-LCD displays have gradually occupied the mainstream position of flat panel displays in their respective fields. However, due to the limitations of the liquid crystal material itself, TFT-LCD still has many defects such as insufficient fast response, insufficient voltage, and insufficient charge retention rate. Therefore, it is particularly important to find single crystal compounds with low viscosity and high dielectric anisotropy.

As early as 1992, Merck of Germany described monomeric liquid crystals with terminal -O(CH2)nF in patent DE4222371.

Contents of the invention

Against the background above, the present invention provides a novel liquid crystal compound, which has both triphenyl or quaterphenyl and -O(CH ₂ )nF unit structures. The compound has the characteristics of large optical anisotropy and stable structure, and has the structure I shown in the formula:

RA ₁ -A ₂ -A ₃ -A ₄ -O(CH ₂ )nF

(I)

Wherein, R is selected from H and unsubstituted or substituted alkyl or alkoxy groups each containing 1-12 carbon atoms; one or more of substituted alkyl or alkoxy groups each containing 1-12 carbon atoms The _CH2 groups are each independently of each other by -C≡C-, -CF2O-, -CH= _CH- , -O-, -CO-O- or -O-CO- with O atoms not directly bonded to each other and one or more H atoms may be replaced by halogen;

A ₁ , A ₂ , A ₃ and A ₄ are each independently selected from: a single bond or 1,4-phenyl, wherein the hydrogens of the 1,4-phenyl can be each independently replaced by one or more halogens; and A ₁ , A ₂ , A ₃ and A ₄ at most one is a single bond;

n is 2, 3 or 4.

The halogen described in the present invention is preferably F.

The liquid crystal compound containing a tri- or quadrphenyl structure in the present invention has the advantage of large optical anisotropy because of the tri- or quadrphenyl structure in the structure, which is beneficial to reduce the cell thickness of the liquid crystal display device and improve the response. speed.

Among them, the liquid crystal compound described in the present invention is preferably:

R is selected from H or an unsubstituted alkyl group containing 1-5 carbon atoms;

A ₁ , A ₂ , A ₃ and A ₄ are each independently selected from: a single bond or 1,4-phenyl, wherein the hydrogens of the 1,4-phenyl can be each independently replaced by one or more fluorine atoms; and At most one of A ₁ , A ₂ , A ₃ and A ₄ is a single bond;

n is 2, 3 or 4.

And more preferably, the liquid crystal compound is selected from compounds of the following general formula:

Wherein, R is selected from alkyl groups containing 2-5 carbon atoms;

n is 2, 3 or 4, preferably 2 or 3.

As the most preferred technical solution of the present invention, the liquid crystal compound is: or

The above compounds have larger optical anisotropy, and after being applied to the composition, the optical anisotropy can be improved, the cell thickness can be reduced, and a rapid response can be realized.

The second object of the present invention is to provide a preparation method of a liquid crystal compound containing a tri- or quadrphenyl structure, the synthesis route of the preparation method is as follows:

RA ₁ -A ₂ -A ₃ -I+F(CH ₂ )nO-A ₄ -B(OH) ₂ →RA ₁ -A ₂ -A ₃ -A ₄ -O(CH ₂ )nF

Ⅱ-1Ⅱ-2

Starting materials RA ₁ -A ₂ -A ₃ -I(II-1) and F(CH ₂ )nO-A ₄ -B(OH) ₂ , using tetrakistriphenylphosphine palladium as catalyst and sodium carbonate as binding agent Acid agent, reflux for 4-8 hours to react to obtain RA ₁ -A ₂ -A ₃ -A ₄ -O(CH ₂ )nF(II-2), wherein, R, A ₁ , A ₂ , A ₃ , A ₄ and The reference of n is the same as above, I is iodine, and B is boron.

Among them, the reaction time is preferably 6 hours.

Wherein, the reaction uses toluene, ethanol or a mixture thereof as a solvent.

By adopting the above preparation method, the liquid crystal compound containing the triphenyl or quadrphenyl structure can be stably obtained in batches, and has the advantage of large optical anisotropy.

The third object of the present invention is to protect the application of the above-mentioned liquid crystal compound containing a tri- or quadrphenyl structure in the field of liquid crystal display.

Specifically, the present invention claims a liquid crystal composition containing the above-mentioned liquid crystal compound containing a triphenyl or quadrphenyl structure. The liquid crystal compound containing the triphenyl or quadrphenyl structure is added in a reasonable manner, that is, the addition amount of the liquid crystal compound containing the triphenyl or quadrphenyl structure is preferably 1-80%, more preferably 3-50%. Those skilled in the art can foresee that based on the addition of the above-mentioned liquid crystal compound, the optical anisotropy of the existing conventional liquid crystal composition can be further improved, which has the technical effect of realizing fast response.

As a preferred technical solution of the present invention, the composition has the following ratio by weight percentage:

The present invention further claims the application of the above composition in a liquid crystal display device, which includes but not limited to TN, ADS, FFS or IPS liquid crystal display. After the liquid crystal composition is applied to the liquid crystal display device, it has the advantage of quick response.

Each performance test parameter abbreviation is as follows among the present invention:

Δε represents the dielectric anisotropy at 25°C and 1kHz;

γ1 represents the rotational viscosity (mPa·s) at 25°C.

△n is optical anisotropy, no is refractive index (589nm, 25°C);

C.p is the clearing point (℃) of the liquid crystal composition;

VHR charge retention rate (%): inject the mixed liquid crystal into the liquid crystal cell, put it into the incubator, and enter the test program after the temperature is stable, and manually take points to obtain the value of the charge retention rate. The measured voltage is 5V, the power-on time is 5ms, and the HoldingTime is 500ms.

detailed description

Example 1

Synthesis of 3,5,2'-trifluoro-4-(3-fluoropropoxy)-4″-propyl-[1,1';4',1″]terphenyl (Compound 3)

Add 26mL of absolute ethanol, 50mL of toluene and 50mL of water into a 200mL three-necked flask, start stirring, add 12.9g of 3,5-difluoro-4-(3-fluoropropoxy)phenylboronic acid (compound 1), 17.0g of 3-fluoro- 4-iodo-4'-propylbiphenyl (compound 2) and 11.7 g of anhydrous sodium carbonate. The nitrogen gas was substituted three times, and 0.25 g of tetrakis(triphenylphosphine)palladium was added. When heating to the liquid phase at 60°C, slowly heat to reflux and react at reflux for 6 hours.

After the reflux was completed, 40 mL of water was added to the reaction kettle, stirred for 10 minutes, left to stand for liquid separation, and the organic phase was washed twice with 40 mL×2 water. Add 3 times of petroleum ether and 1 times of ethyl acetate, heat to dissolve, and perform column chromatography. The solvent was spin-dried and recrystallized three times with 3 times ethanol, and the white solid was dried by suction filtration.

Theoretical yield: 20.1g, actual yield: 16.5g, yield 82.1%.

Gas phase purity (GC) 99.9%,

Melting point: 43.9°C, clearing point: 116.9°C,

Δn is 0.215,

Δε is 11.50,

γ1 is 138mPa·s.

Mass spectrometry fragments: 313, 342, 373, 402 (molecular ion peaks);

H-NMR spectrum (CDCl ₃ , 300mhZ): δH: 0.90-2.60 (m, 9H), 3.90-4.10 (m, 4H), 6.80-7.50 (m, 9H).

Example 2

Synthesis of 3,5,2'-trifluoro-4-(2-fluoroethoxy)-4″-propyl-[1,1';4',1″]terphenyl (compound 5)

Add 26mL of absolute ethanol, 50mL of toluene and 50mL of water into a 200mL three-necked flask, start stirring, add 12.0g of 3,5-difluoro-4-(2-fluoroethoxy)phenylboronic acid (compound 4), 17.0g of 3-fluoro- 4-iodo-4'-propylbiphenyl (compound 2) and 11.7 g of anhydrous sodium carbonate. The nitrogen gas was substituted three times, and 0.25 g of tetrakis(triphenylphosphine)palladium was added. When heating to the liquid phase at 60°C, slowly heat to reflux and react at reflux for 6 hours.

After the reflux was completed, 40 mL of water was added to the reaction kettle, stirred for 10 minutes, left to stand for liquid separation, and the organic phase was washed twice with 40 mL×2 water. Add 3 times of petroleum ether and 1 times of ethyl acetate, heat to dissolve, and perform column chromatography. The solvent was spin-dried and recrystallized three times with 3 times ethanol, and the white solid was dried by suction filtration.

Theoretical yield: 19.4g, actual yield: 16.0g, yield 82.4%.

Gas phase purity (GC) 99.9%,

Δn is 0.226,

Δε is 12.60,

γ1 is 125mPa·s.

Mass spectrometry fragments: 299, 328, 359, 388 (molecular ion peaks);

H-NMR spectrum (CDCl ₃ , 300mhZ): δH: 0.90-2.60 (m, 7H), 3.90-4.10 (m, 4H), 6.80-7.50 (m, 9H).

According to the technical scheme of Example 1, the following compounds can be synthesized by simply replacing the raw materials containing corresponding groups:

Embodiment 3 mixed crystal composition

The liquid crystal monomers used in the following compositions were all provided by Beijing Bayi Space-Time Liquid Crystal Technology Co., Ltd. Unless otherwise specified, the contents of each component in the examples represent mass percentages.

Take the following liquid crystal compounds in parts by weight and prepare a liquid crystal composition. The specific proportion and performance parameters of the obtained liquid crystal composition are shown in the table below.

The application results of liquid crystal compounds with triple or quadrphenyl and -O(CH ₂ )nF structures in TN, IPS, FFS, ADS, VA-TFT modes are shown in Table 1-2.

Table 1, parts by weight and performance parameters of each component in the liquid crystal composition of the present invention

Table 2. Parts by weight and performance parameters of each component in the existing liquid crystal composition

It can be seen from Table 1-2 that the liquid crystal composition added with the compound of the present invention has a short response time, a large Δn value, a high charge retention rate, and a large dielectric anisotropy. The addition amount of the compound is preferably 1-80%, more preferably 3-50%.

In addition to the compositions exemplified in the test examples, other liquid crystal compositions provided by the present invention with other liquid crystal compounds having a structure of triphenyl or quaterphenyl and -O(CH ₂ )nF can obtain the same excellent optical and electrical properties.

Although the present invention has been described in detail with general descriptions and specific embodiments above, it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, the modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the protection scope of the present invention.

Claims (9)

1. A liquid crystal compound containing a tri- or quadrphenyl structure, characterized in that: the liquid crystal compound has a structure as shown in formula I: (I) Wherein, R is selected from H or an unsubstituted alkyl group containing 1-5 carbon atoms; A ₁ and A ₂ are each independently selected from: a single bond or 1,4-phenyl, wherein one or more hydrogens of the 1,4-phenyl may be each independently replaced by a fluorine atom; and A ₁ and A ₂ are at most One is a single key; A3 is 1,4 _- phenyl, wherein one or more hydrogens of 1,4-phenyl are independently replaced by fluorine atoms; A ₄ is 1,4-phenyl, wherein one or more hydrogens of 1,4-phenyl can be independently replaced by fluorine atoms; n is 2, 3 or 4. 2. The liquid crystal compound according to claim 1, characterized in that: the liquid crystal compound is selected from compounds of the following general formula: Wherein, R is selected from alkyl groups containing 2-5 carbon atoms; n is 2, 3 or 4. 3. The liquid crystal compound according to claim 2, characterized in that: the liquid crystal compound is: 4. the preparation method of the liquid crystal compound containing three or four biphenyl structures, it is characterized in that: Ⅱ-1Ⅱ-2 Starting materials and , using tetrakistriphenylphosphine palladium as a catalyst, sodium carbonate as an acid-binding agent, and reacting for 4-8 hours under reflux to obtain , wherein R, A ₁ , A ₂ , A ₃ , A ₄ and n refer to any one of claims 1-3. 5. The preparation method according to claim 4, characterized in that: said reaction takes toluene, ethanol or a mixture thereof as a solvent. 6. The application of the liquid crystal compound according to any one of claims 1-3 in the field of liquid crystal display. 7. A liquid crystal composition containing the liquid crystal compound according to any one of claims 1-3. 8. The composition according to claim 7, characterized in that, by weight, the liquid crystal compound of any one of claims 1-3 is added in an amount of 1-80% in the composition. 9. The application of the composition according to claim 7 or 8 in the manufacture of a liquid crystal display device, characterized in that: the liquid crystal display device is a TN, ADS, FFS or IPS liquid crystal display.