Liquid crystal compound containing a difluormethoxy bridge and application thereof

Abstract

The present invention relates to a liquid crystal compound having a structure as shown by formula I, wherein R is selected from H and alkyl or alkoxy containing 1-12 carbon atoms in which one or more H are unsubstituted or substituted with halogens; A.sub.1, A.sub.2 and A.sub.3 are each independently selected from: a single bond, 1,4-cyclohexylene, 1,4-phenylene, wherein hydrogen in 1,4-phenylene may be each independently substituted with one or more halogens; and Z.sub.1 and Z.sub.2 are each independently selected from a single bond or (CH.sub.2).sub.2. The compound of the invention has the characteristics of low rotational viscosity, large dielectric anisotropy, good mutual solubility and stability. The driving voltage of a device can be remarkably reduced after the compound is added to a composition. Thus, the compound of the invention has prosperous applications in LCD industry. ##STR00001##

Claims

1. A liquid crystal compound comprising a difluoromethoxy bridge structure as shown by formula (I): ##STR00049## wherein R is selected from H, and alkyl or alkoxy containing 1-12 carbon atoms, wherein one or more H in alkyl or alkoxy are unsubstituted or substituted with halogens; A.sub.1, A.sub.2 and A.sub.3 are each independently selected from: a single bond, 1,4-cyclohexylene and 1,4-phenylene, when A.sub.1, A.sub.2, A.sub.3 denote 1,4-phenylene, wherein hydrogen in A.sub.1, A.sub.2, A.sub.3 may be each independently substituted with one or more halogens; and Z.sub.1 and Z.sub.2 are each independently selected from a single bond or (CH.sub.2).sub.2.

2. The liquid crystal compound according to claim 1, wherein the compound is characterized in that R is selected from H and alkyl or alkoxy containing 1-5 carbon atoms in which one or more H are unsubstituted or substituted with halogens; the halogen is fluorine, chlorine, bromine or iodine; A.sub.1, A.sub.2 and A.sub.3 are each independently selected from: a single bond, 1,4-cyclohexylene, and 1,4-phenylene, wherein hydrogen in 1,4-phenylene may each be independently substituted with one or more halogens; and the halogen is fluorine, chlorine, bromine or iodine; and Z.sub.1 and Z.sub.2 are both single bonds.

3. The liquid crystal compound according to claim 1, wherein the compound is characterized in that R is selected from H and unsubstituted alkyl containing 1-5 carbon atoms; A.sub.1 is selected from a single bond, 1,4-cyclohexylene and 1,4-phenylene, wherein hydrogen in 1,4-phenylene may be each independently substituted with one or more halogens; the halogen is fluorine, chlorine, bromine or iodine; A.sub.2 and A.sub.3 are each independently selected from 1,4-cyclohexylene and 1,4-phenylene, wherein hydrogen in 1,4-phenylene may be each independently substituted with one or more halogens; the halogen is fluorine, chlorine, bromine or iodine; and Z.sub.1 and Z.sub.2 are both single bonds.

4. The liquid crystal compound according to claim 3, wherein the compound is characterized in that the halogen is fluorine.

5. The liquid crystal compound according to claim 1, wherein the liquid crystal compound is selected from liquid crystal compounds having structures represented by the following general formulas: ##STR00050## wherein R is selected from alkyl having 1-5 carbon atoms.

6. The liquid crystal compound according to claim 5, wherein the liquid crystal compound is: ##STR00051##

7. A liquid crystal composition containing the liquid crystal compound according to claim 1.

8. The liquid crystal composition according to claim 7, wherein the percentage of the liquid crystal compound is in the range of 1-80%.

9. A liquid crystal display comprising the liquid crystal compound according to claim 1.

10. A liquid crystal display comprising the liquid crystal composition according to claim 7.

11. A liquid crystal display comprising the liquid crystal composition according to claim 8.

12. The liquid crystal composition according to claim 7, wherein the percentage of the liquid crystal compound is in the range of 3-50%.

13. A liquid crystal display comprising the liquid crystal composition according to claim 12.

14. The liquid crystal compound according to claim 2, wherein the halogen is fluorine.

15. The liquid crystal compound according to claim 3, wherein the halogen is fluorine.

Description

DETAILED DESCRIPTION

Example 1

(1) ##STR00006##

Synthesis of 4-[(3,4,5-trifluoro-2-methyl-phenoxy)-difluoromethyl]-3,5,2-trifluoro-4-propyl-[1,1; 4,1]terphenyl (Compound 7)

1) Synthesis of 2-(3,4,5-trifluoro-phenoxy)-tetrahydropyran (Compound 2)

(2) ##STR00007##

(3) 70 g 3,4,5-trifluorophenol, 72 g 2,3-dihydropyran and 140 ml dichloromethane were added into a 500 ml dried and clean three-necked flask, stirred, added dropwise with 5 drops of concentrated hydrochloric acid slowly at room temperature, and reacted for 3 hours after the completion of the dropwise addition. The reaction solution was washed twice with 100 ml 10% aqueous sodium hydroxide solution, dried with 20 g anhydrous sodium sulfate for 30 minutes and subjected to suction filtration, and the filtrate is spin-dried for later use.

2) Synthesis of 2-(3,4,5-trifluoro-2-methyl-phenoxy)-tetrahydropyran (Compound 3)

(4) ##STR00008##

(5) 97 g 2-(3,4,5-trifluoro-phenoxy)-tetrahydropyran (Compound 2) and 500 ml tetrahydrofuran were added into a 1 L dried and clean three-necked flask, protected under nitrogen, cooled to 75 C. to 85 C. by using liquid nitrogen, added dropwise with 200 ml butyllithium, reacted for 1 hour under a control of temperature after the completion of dropwise addition, added dropwise with 89 g methyl iodide, reacted for 30 minutes at a temperature controlled at 75 C. to 85 C. after the completion of dropwise addition, and then the temperature was naturally raised to 20 C., the reaction solution was hydrolyzed and destroyed with an aqueous ammonium chloride solution. Liquid separation was performed, the aqueous phase was extracted twice with 100 ml ethyl acetate, the organic phases were combined, washed twice with 100 ml aqueous sodium chloride solution, dried with 30 g anhydrous sodium sulfate for 30 minutes and subjected to suction filtration, and the filtrate is spin-dried and crystallized with 1.5 times of ethanol to obtain a white solid.

(6) Theoretical production: 102 g, actual production: 64 g, yield: 62.7%, white solid, GC: 99.6%, melting point: 67.65 C.

3) Synthesis of 3,4,5-trifluoro-2-methyl-phenol (Compound 4)

(7) ##STR00009##

(8) 10 g 2-(3,4,5-trifluoro-2-methyl-phenoxy)-tetrahydropyran (Compound 3), 2 g of pyridinium p-toluenesulfonate and 50 ml of ethanol were added into a 100 ml dried and clean three-necked flask, stirred and heated to 60 C.-70 C., and reacted for 3 hours in a timing manner. The reaction solution was spin-dried, added with 20 ml dichloromethane to dissolve the product, washed twice with 10 ml aqueous sodium chloride solution and dried with 10 g anhydrous sodium sulfate for several minutes and spin-dried.

(9) Theoretical production: 6.5 g, actual production: 6.5 g, yield: 100% (according to the theoretical basis), a colorless liquid, GC: 99.155%.

4) Synthesis of onium trifluoromethyl sulfonate (Compound 6)

(10) ##STR00010##

(11) 137 g 3,5,2-trifluoro-4-propyl-[1,1; 4,1] terphenyl-4-carboxylic acid (Compound 5), 47 mL 1,3-propanedithiol, 42 mL trifluoromethyl sulfonic acid, 145 mL toluene and 145 mL isooctane were added into a 1 L three-necked flask, a water separator was mounted at one side opening, the temperature was raised until the refluxing was generated, the reaction was conducted for 6 hours, slowly cooled to 0 C. and subjected to suction-filtration to obtain a solid. The solid was dried for further feeding.

5) Synthesis of 4-[(3,4,5-trifluoro-2-methyl-phenoxy)-difluoromethyl]-3,5,2-trifluoro-4-propyl-[1,1; 4,1]terphenyl (Compound 7)

(12) ##STR00011##

(13) 200 mL dichloromethane, 39 mL triethylamine and 45.4 g 3,4,5-trifluoro-2-methyl-phenol (Compound 4) were added into a 2 L three-necked flask and cooled to 20 C., added with a solution composed of 142 g onium trifloromethyl sulfonate (Compound 6) and 400 mL dichloromethane and stirred for 1 hour. The temperature is controlled below 75 C., 77 g hydrogen fluoride triethylamine was added dropwise and the stirring was continued for 1 hour. The temperature is controlled below 75 C., a solution composed of 15 mL bromine and 30 mL dichloromethane was re-warmed to 10 C. and was subjected to post-processing. 1 L water was added into a 10 L bucket, the stirring was started, the reaction solution was poured and stirred for several minutes, the sodium bicarbonate solid was added slowly (a large amount of gas was generated) until the pH of the solution was nearly neutral, standing for liquid separation, the aqueous phase was extracted once with 500 ml dichloromethane, the organic phases were combined, and the solvent was spin-dried at 70 C. to obtain a solid, recrystallization was carried out with 2-fold ethanol and one-fold toluene for three times and the suction-filtration and air-drying were performed to obtain a white solid. Theoretical production: 128.6 g, actual production: 103 g, yield: 80.0%.

(14) Gas chromatographic (GC) purity is 99.9%,

(15) Melting point: 70.9 C.,

(16) n is 0.197,

(17) is 31.5, and

(18) 1 is 208 mPa.Math.s.

(19) Mass spectrometry fragment: 173,346,375,536 (molecular ion peak);

(20) H-NMR spectrum (CDCl3,300 MHz): H: 0.90-2.60 (m, 10H), 6.10-7.60 (m, 10H).

Example 2

(21) ##STR00012##

Synthesis of 4-[(3,4,5-trifluoro-2-methyl-phenoxy)-]-difluoro methyl-3,5-difluoro-4-propyl biphenyl (Compound 10)

1) Synthesis of onium trifluoromethyl sulfonate (Compound 9)

(22) ##STR00013##

(23) 102 g 4-propyl-3,5-difluorodiphenyl carboxylic acid (compound 8), 47 mL 1,3-propanedithiol, 42 mL trifluoromethyl sulfonic acid, 145 mL toluene and 145 mL isooctane were added into a 1 L three-necked flask, a water separator was mounted at one side opening, the temperature was raised until the refluxing was generated, the reaction was conducted for 6 hours, slowly cooled to 0 C. and was subjected to suction-filtration to obtain a solid, the solid was dried for further feeding.

2) Synthesis of 4-[(3,4,5-trifluoro-2-methyl-phenoxy)-]-difluoromethyl-3,5-difluoro-4-propyl biphenyl (Compound 10)

(24) ##STR00014##

(25) 200 mL dichloromethane, 39 mL triethylamine and 45.4 g 3,5-difluoro-4-(3-fluoro-propoxy)-phenol (Compound 4) were added into a 2 L three-necked flask, cooled to 20 C., added with a solution composed of 117 g onium trifluoromethyl sulfonate (Compound 10) and 200 mL dichloromethane and stirred for 1 hour. The temperature was controlled below 75 C., 77 g hydrogen fluoride triethylamine was dropwise added and the stirring was continued for 1 hour. The temperature was controlled below 75 C., a solution composed of 15 mL bromine and 30 mL dichloromethane was re-warmed to 10 C. and subjected to post-processing. 1 L water was added into a 10 L bucket, the stirring was started, the reaction solution was poured and stirred for several minutes, the sodium bicarbonate solid was added slowly (a large amount of gas was generated) until the pH of the solution was nearly neutral, standing for liquid separation, the aqueous phase was extracted once with 500 ml dichloromethane, the organic phases were combined, and the solvent was spin-dried at 70 C. to obtain a sticky substance, recrystallization was carried out with 2-fold ethanol and 0.5-fold petroleum ether for three times and the suction-filtration and air-drying were performed to obtain a white solid. Theoretical production: 106 g, actual production: 69 g, yield: 65.1%.

(26) Gas chromatographic (GC) purity is 99.9%,

(27) n is 0.133,

(28) is 23.0, and

(29) 1 is 52.1 mPa.Math.s.

(30) Mass spectrometry fragment: 252, 281, 442 (molecular ion peak);

(31) H-NMR spectrum (CDCl3, 300 MHz): H: 0.90-2.60 (m, 10H), 6.10-7.50 (m, 7H).

Example 3

(32) ##STR00015##

Synthesis of 4-[(3,4,5-trifluoro-2-methyl-phenoxy)-]-difluoromethyl-2,3,5-trifluoro-4-propyl biphenyl (Compound 13)

1) Synthesis of onium trifluoromethyl sulfonate (Compound 11)

(33) ##STR00016##

(34) 65 g 4-propyl-2,3,5-trifluorodiphenyl carboxylic acid (compound II), 28 mL 1,3-propanedithiol, 25 mL trifluoromethyl sulfonic acid, 90 mL toluene and 90 mL isooctane were added into a 1 L three-necked flask, a water separator was mounted at one side opening, the temperature was raised until the refluxing was generated, the reaction was conducted for 6 hours, slowly cooled to 0 C. and was subjected to suction-filtration to obtain a solid, the solid was dried for further feeding.

2) Synthesis of 4-[(3,4,5-trifluoro-2-methyl-phenoxy)-]-difluoromethyl-3,5-difluoro-4-propyl biphenyl (Compound 10)

(35) ##STR00017##

(36) 100 mL dichloromethane, 20 mL triethylamine and 23 g 3,5-difluoro-4-(3-fluoropropoxy)-phenol (Compound 4) were added into a 2 L three-necked flask, cooled to 20 C., added with a solution composed of 60.6 g onium trifluoromethyl sulfonate (compound II) and 100 mL dichloromethane and stirred for 1 hour. The temperature was controlled below 75 C., 38 g hydrogen fluoride triethylamine was added dropwise and the stirring was continued for 1 hour. The temperature was controlled below 75 C., a solution composed of 8 mL bromine and 15 mL dichloromethane was re-warmed to 10 C. and subjected to post-processing. 0.5 L water was added into a 5 L bucket, the stirring was started, the reaction solution was poured and stirred for several minutes, the sodium bicarbonate solid was added slowly (a large amount of gas was generated) until the pH of the solution was nearly neutral, standing for liquid separation, the aqueous phase was extracted once with 250 ml dichloromethane, the organic phases were combined, and the solvent was spin-dried at 70 C. to obtain a sticky substance, recrystallization was carried out with 2-fold ethanol and 0.5-fold petroleum ether for three times and the suction-filtration and air-drying were performed to obtain a white solid. Theoretical production: 60.6 g, actual production: 38.3 g, yield: 63%.

(37) Gas chromatographic (GC) purity is 99.9%,

(38) n is 0.125,

(39) is 26.5, and

(40) 1 is 59.8 mPa.Math.s.

(41) Mass spectrometry fragment: 270,299,460 (molecular ion peak);

(42) H-NMR spectrum (CDCl3, 300 MHz): H: 0.90-2.60 (m, 10H), 6.10-7.50 (m, 6H).

Examples 4-17

(43) According to technical solutions of Examples 1-3, the following compounds can be synthesized by simply replacing starting materials containing the corresponding groups (without substantively adjusting the specific preparation methods):

(44) ##STR00018## ##STR00019##

Example 18 Mixed Crystal Composition

(45) Liquid crystal monomers used in the following composition are all provided by BEIJING BAYI SPACE LCD TECHNOLOGY CO., LTD. Unless otherwise specified, the content of each component in the examples is expressed as a mass percentage.

(46) Liquid crystal compounds having the following parts by weight were taken and used for preparing a liquid crystal composition. The specific ratio and performance parameters of the resulting liquid crystal composition are shown in the following table.

(47) The liquid crystal compound having difluoromethoxy bridge has been successfully applied in TN, IPS, FFS, ADS-TFT modes, the results are shown in Tables 1-3.

(48) TABLE-US-00001 TABLE 1 Parts by weight of each component and performance parameters of the liquid crystal composition Components Parts Performance Parameters 0 10 n 0.101 22.5 8.21 22.5 1 86.1 18 C.p ( C.) 81.5 13.5 VHR (%) 99.5 13.5

(49) TABLE-US-00002 TABLE 2 Parts by weight of each component and performance parameters of the liquid crystal composition Components Parts Performance Parameters 10 n 0.093 22.5 7.37 22.5 1 70.5 18 C.p ( C.) 70.2 0 13.5 VHR (%) 99.5 13.5

(50) TABLE-US-00003 TABLE 3 Performance parameters of the liquid crystal composition containing the liquid crystal compounds Components Parts Performance Parameters 10 n 0.091 22.5 7.72 22.5 1 71.23 18 C.p ( C.) 68.7 13.5 VHR (%) 99.5 13.5

(51) TABLE-US-00004 TABLE 4 Performance parameters of the liquid crystal composition without the addition of the compound of the invention Components Parts Performance Parameters 25 n 0.090 25 4.86 0 20 1 83.4 15 C.p ( C.) 79.1 15 VHR (%) 99.5

(52) TABLE-US-00005 TABLE 5 Parts by weight of each component and performance parameters of the liquid crystal composition Components Parts Performance Parameters 10 n 0.095 22.5 6.05 22.5 1 82.1 18 C.p ( C.) 80.5 13.5 VHR (%) 99.5 13.5

(53) It can be seen from Tables 1-5 above, that a liquid crystal composition, wherein either the compound of the invention is directly added or the traditional dielectric anisotropy compound (Compound 14) is replaced by the compound of the invention, is moderate in both rotational viscosity and n value and high in voltage holding ratio, in particular, is of very high dielectric anisotropy. Meanwhile, in the liquid crystal composition of the present invention, the adding percentage of the compound is in the range of 1-80% and more preferably, in the range of 3-50%.

(54) In addition to the compositions exemplified in the experimental examples, other liquid crystal compositions consisted of other liquid crystal compounds having difluoromethoxy bridge structure introduced in the current invention can also achieve an excellent electro-optical performance.

(55) Although the present invention has been described in detail with general explanation, specific embodiments and experiments, it is obvious to a person skilled in the art that a variety of modifications or improvements can be made based on the present invention. Therefore, all these modifications and improvements made without departing from the scope of the present invention belong to the scope claimed in the invention.