A dichroic dye compound and applications thereof

Abstract

The present application relates to the technical field of liquid crystal display, and particularly relates to a dichroic dye compound and application thereof. The dichroic dye compound provided by the present application has a large order parameter, can be widely applied in mixed liquid crystal materials, and makes the liquid crystal display device using the dichroic dye compound have a good contrast.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal display technology, and more particularly to a dichroic dye compound and its applications. Background Technology

[0002] Digital display has become the mainstream display technology in the 21st century. Compared with other display technologies, liquid crystal displays have the characteristics of low voltage, low power consumption, and portability, and are easy to achieve in thin, light and large flat panel displays.

[0003] In liquid crystal display materials, dye-based liquid crystals operate in a host-guest configuration. Nematic liquid crystals serve as the host display material, while dyes act as additives, miscible with the liquid crystal material. When an electric current is applied, the movement of liquid crystal molecules carries the dye molecules along with them, achieving the display effect. Therefore, the dyes used in liquid crystal displays must have excellent compatibility with the liquid crystal material, a molecular structure similar to that of the liquid crystal molecules, and excellent chemical, optical, and thermal stability. Multicolor dye-based liquid crystals, with their high contrast, clear display, and aesthetically pleasing content, have long been favored by high-end products such as automotive dashboards and smart windows.

[0004] There are many types of dyes used in liquid crystals, including azo, anthraquinone, azazine, and oxanthracene dyes. These dyes must have excellent compatibility with the liquid crystal components and, when added to the mixed liquid crystal, not reduce the stability of the mixed liquid crystal material. Under the influence of an electric field, they can twist synchronously with the liquid crystal molecules, possessing the same orientation vector as the liquid crystal molecules. When displayed, they produce very bright colors, and when turned off, they are colorless.

[0005] Among dichroic dyes for liquid crystals, azo compounds, with their rod-shaped molecular structure, exhibit good compatibility and stability with liquid crystal materials. When doped with liquid crystals, they display excellent photoelectric properties, such as wide viewing angles and increased brightness, and are therefore widely used in dye-based liquid crystals. However, the contrast ratio of these dyes needs further improvement. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a dichroic dye compound and its application. The dichroic dye compound provided by this invention has a large order parameter and can be widely used in mixed liquid crystal materials, thereby enabling liquid crystal display devices using it to have better contrast.

[0007] In a first aspect, the present invention provides a dichroic dye compound having a structure as shown in Formula I:

[0008] Formula I;

[0009] Wherein, R1 is selected from H, straight-chain or branched alkyl groups with 1 to 10 carbon atoms; R2 is selected from H, F, N(R3)2, F-substituted or unsubstituted alkyl groups with 1 to 10 carbon atoms, F-substituted or unsubstituted alkoxy groups with 1 to 10 carbon atoms, F-substituted or unsubstituted alkenyl groups with 2 to 10 carbon atoms, and cycloalkyl groups with 3 to 5 carbon atoms.

[0010] R3 is selected from any one of the following: an alkyl group with 1 to 10 carbon atoms that is F-substituted or unsubstituted; an alkenyl group with 2 to 10 carbon atoms that is F-substituted or unsubstituted; or a cycloalkyl group with 3 to 5 carbon atoms; further, R3 is CH3, C2H5, C3H7, C4H9, or C5H 11 C6H 13 ;

[0011] Furthermore, R2 can be H, CH3, C2H5, C3H7, C4H9, or C5H. 11 , CH2CH2CH(C2H5)CH2CH3, CH2CH(C2H5)(CH2)3CH3, OCH3, OC2H5, OC3H7, OC4H9, OC5H 11 , N(CH3)2, N(C2H5)2, N(C3H7)2, N(C4H9)2, N(C5H 11 )2 or N(C6H 13 )2;

[0012] X1 and X2 are each independently H, CH3, C2H5, C3H7, C4H9, CH2CH(CH3)2, F or Cl;

[0013] A1 and A2 are independently selected from direct bonds or at least one of the following structures:

[0014] , , , , , ;

[0015] A3 and A4 are independently selected from direct bonds or at least one of the following structures:

[0016] , , , , , , , , , , , , ;

[0017] *—、—* represent the connecting bonds of functional groups;

[0018] Z1 and Z2 are each independently selected from any one of the following: single bond, -CH2-, -CH2CH2-, -CH2O-, -N=N-, or -CF2O-;

[0019] a and b are 1 or 2.

[0020] As a preferred embodiment of the present invention, the compound having the structure shown in Formula I is selected from any one or more of the following compounds:

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038] In this invention, unless otherwise specified, "C" refers to... n H 2n+1 " indicates an alkyl group (e.g., C3H7, C4H9, C5H)11、 C6H 13 (etc.) all refer to straight-chain alkyl groups.

[0039] In a second aspect, the present invention provides a liquid crystal composition comprising any one or more of the dichroic dye compounds described in the first aspect.

[0040] As a preferred embodiment of the present invention, the liquid crystal composition further includes a host material, which comprises any one or more of the following compounds:

[0041] ;

[0042] Among them, R6, R7, R8, R9, R 10 R 11 R 12 Each of the following is independently selected from H, F, N(R5)2, F-substituted or unsubstituted alkyl groups of 1 to 10 carbon atoms, F-substituted or unsubstituted alkoxy groups of 1 to 10 carbon atoms, F-substituted or unsubstituted alkenyl groups of 2 to 10 carbon atoms, and F-substituted or unsubstituted cycloalkyl groups of 3 to 5 carbon atoms; R5 is selected from F-substituted or unsubstituted alkyl groups of 1 to 10 carbon atoms, F-substituted or unsubstituted alkenyl groups of 2 to 10 carbon atoms, and F-substituted or unsubstituted cycloalkyl groups of 3 to 5 carbon atoms. Wherein, 1 to 10 can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10; 2 to 10 can be 2, 3, 4, 5, 6, 7, 8, 9, 10; and 3 to 5 can be 3, 4, 5.

[0043] As a preferred embodiment of the present invention, the content of the dichroic dye compound is 0.1-15% based on the total mass of the liquid crystal composition (100%), for example, 0.1%, 0.5%, 1%, 3%, 5%, 8%, 10%, 12%, 15%, etc. However, the present invention is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0044] As a preferred embodiment of the present invention, the content of the dichroic dye compound is 0.1-10% based on the total mass of the liquid crystal composition being 100%.

[0045] Thirdly, the present invention provides the use of the dichroic dye compound described in the first aspect or the liquid crystal composition described in the second aspect in a liquid crystal display device.

[0046] As a preferred technical solution of the present invention, the liquid crystal display device includes, but is not limited to, VA (Vertical Alignment) liquid crystal displays, TN (Twisted Nematic) liquid crystal displays, STN (Super-twisted Nematic) liquid crystal displays, FFS (Fringing Field Switching) liquid crystal displays, IPS (In Plane Switching) liquid crystal displays, automotive instrument panels, and smart windows.

[0047] The technical solution provided by the embodiments of the present invention has the following advantages compared with the prior art:

[0048] The dichroic dye compound provided by this invention has a large order parameter and can be widely used in mixed liquid crystal materials, so that the liquid crystal display device using it has better contrast. Detailed Implementation

[0049] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0050] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0051] Example 1

[0052] This embodiment provides a dichroic dye compound and its preparation method. The structural formula of the dichroic dye compound is as follows:

[0053] The synthesis route is as follows:

[0054]

[0055] The synthesis steps are as follows:

[0056] 1. Synthesis of BYLC-098-3

[0057] Add 134 g BYLC-098-2 (2-thiopheneboronic acid, CAS No.: 6165-68-0), 243 g BYLC-098-1, 400 ml tetrahydrofuran, and 600 ml water to a clean, dry 2L three-necked flask. Start stirring, add 77.4 g sodium bicarbonate and 12.3 g tetrabutylammonium bromide, and continuously purge with nitrogen for 5 minutes. Add 0.3 g dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine palladium, and heat to reflux (about 70°C). Reflux for 3 hours.

[0058] Post-treatment: The reaction solution was cooled to room temperature, and 200 ml of water and 200 ml of toluene were added. The mixture was stirred for 5 minutes and separated. The aqueous phase was extracted with 200 ml of toluene. The organic phases were combined and washed once with 300 ml of water. The organic phase was concentrated to 243 g of a brownish-black liquid. The solution was diluted with twice the volume of n-heptane, passed through an 80 g silica gel column, flushed with twice the column height of n-heptane, and concentrated to dryness to 218.7 g of a green liquid. GC 99%. The m / z of the product was 246 (M+).

[0059] Theoretical yield: 246g, actual yield: 221.4g, yield = 90%.

[0060] 2. Synthesis of BYLC-098-4

[0061] Add 1 L of tetrahydrofuran and 86 g of BYLC-098-3 to a clean, dry 2 L three-necked flask, start stirring, and maintain a nitrogen atmosphere throughout. Cool to -75℃ to -85℃ with liquid nitrogen, and add 180 ml of butyllithium dropwise. After the addition is complete, maintain the temperature at -70℃ to -80℃ and react for 2 hours. Then, maintain the temperature at -70℃ to -80℃ and add 90 g of triisopropyl borate dropwise. After the addition is complete, allow the mixture to return to the ambient temperature and react for 2 hours.

[0062] Post-treatment: Maintaining the temperature below 20℃, add 100 ml of dilute hydrochloric acid (hydrochloric acid:water = 1:1) dropwise to the reaction solution, stir for 10 minutes, add 200 ml of water, and stir at -15℃ for 2 hours. Filter, and wash the filter cake once with water. Then add 0.5 times THF and 3 times n-heptane, boil and wash at 50℃ for 0.5 hours, stir at -15℃ for 2 hours, filter, and obtain 90.4 g, HPLC 99%.

[0063] Theoretical yield: 101.5g, actual yield: 91.3g, yield = 90%. The m / z of the product is 290 (M+).

[0064] 3. Synthesis of BYLC-098-6

[0065] In a clean, dry 500 ml three-necked flask, add 43 g of BYLC-098-4, 56 g of BYLC-098-5, 100 ml of tetrahydrofuran, and 150 ml of water in sequence. Start stirring, add 15 g of potassium carbonate and 1.5 g of tetrabutylammonium bromide, and continuously purge with nitrogen for 5 minutes. Add 0.1 g of dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine palladium, and heat to reflux (about 70°C). Reflux for 2 hours.

[0066] Post-processing: After the reaction solution was cooled to room temperature, 300 ml of water, 50 ml of n-heptane, and 50 ml of THF were added and stirred for 10 minutes. The aqueous phase was extracted once with 50 ml of n-heptane and 50 ml of THF. The organic phases were combined and passed through a 10 g silica gel column. The column was flushed with 2 times the column height of n-heptane. The column buffer was concentrated to 40 g at 70 °C. 10 times the volume of n-heptane was added and stirred at room temperature (19 °C) for 20 min. The mixture was then frozen (-17 °C) for 3 h and immediately filtered to obtain 20 g of purplish-black powder, which is BYLC-098-6.

[0067] Theoretical yield: 79.5 g; Actual yield: 47.7 g; Yield: 60%; HPLC accuracy: 99%. The m / z of the product is 566 (M+).

[0068] 4. Synthesis of BYLC-098

[0069] In a clean, dry 500 ml three-necked flask, add 45.4 g of BYLC-098-6, 21 g of BYLC-098-7, 100 ml of tetrahydrofuran, and 150 ml of water in sequence. Start stirring, add 14.6 g of potassium carbonate and 1.5 g of tetrabutylammonium bromide, and continuously purge with nitrogen for 5 minutes. Add 0.1 g of dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine palladium, and heat to reflux (about 70°C). Reflux for 2 hours.

[0070] Post-processing: The reaction solution was cooled to room temperature, and 300 ml of water, 50 ml of toluene, and 50 ml of THF were added. The mixture was stirred for 10 minutes and separated. The aqueous phase was extracted once with 50 ml of toluene and 50 ml of THF. The organic phases were combined and passed through a 10 g silica gel column. The column was flushed with toluene at twice the column height. The column buffer was concentrated to 40 g at 70 °C. Five times the volume of toluene was added and the mixture was stirred at room temperature (19 °C) for 20 min. The mixture was then frozen (-15 °C) for 3 h and immediately filtered to obtain 27.7 g of purplish-black powder, which is BYLC-098.

[0071] Theoretical yield: 55.1 g; Actual yield: 32 g; Yield: 58%; HPLC accuracy: 99%. The m / z of the product is 688 (M+).

[0072] Example 2

[0073] This embodiment provides a dichroic dye compound and its preparation method. The dichroic dye compound is BYLC-008, and its structural formula is as follows:

[0074] .

[0075] The preparation method is the same as in Example 1, except that BYLC-098-7 is replaced with .

[0076] The obtained solid BYLC-008 was analyzed by HPLC-MS, and the m / z of the product was 706 (M+).

[0077] Example 3

[0078] This embodiment provides a dichroic dye compound and its preparation method. The dichroic dye compound is BYLC-011, and its structural formula is as follows:

[0079] .

[0080] The preparation method is the same as in Example 1, except that BYLC-098-7 is replaced with: .

[0081] The obtained solid BYLC-011 was analyzed by HPLC-MS, and the m / z of the product was 790 (M+).

[0082] Example 4

[0083] This embodiment provides a dichroic dye compound and its preparation method. The dichroic dye compound is BYLC-095, and its structural formula is as follows:

[0084] .

[0085] The preparation method is the same as in Example 1, except that the corresponding raw materials are replaced, that is, BYLC-098-7 is replaced with .

[0086] The obtained solid BYLC-095 was analyzed by HPLC-MS, and the m / z of the product was 732 (M+).

[0087] Example 5

[0088] This embodiment provides a dichroic dye compound and its preparation method. The dichroic dye compound is BYLC-076, and its structural formula is as follows:

[0089] .

[0090] The preparation method is the same as in Example 1, except that BYLC-098-7 is replaced with BYLC-098-7. .

[0091] The obtained solid BYLC-076 was analyzed by HPLC-MS, and the m / z of the product was 829 (M+).

[0092] Example 6

[0093] This embodiment provides a dichroic dye compound and its preparation method. The dichroic dye compound is BYLC-081, and its structural formula is as follows:

[0094] .

[0095] The preparation method is the same as in Example 1, except that BYLC-098-5 is replaced with Replace BYLC-098-7 with .

[0096] The obtained colored solid BYLC-81 was analyzed by HPLC-MS, and the m / z of the product was 857 (M+).

[0097] Example 7

[0098] This embodiment provides a dichroic dye compound and its preparation method. The dichroic dye compound is BYLC-070, and its structural formula is as follows:

[0099] .

[0100] The preparation method is the same as in Example 1, except that BYLC-098-5 is replaced with Replace BYLC-098-7 with .

[0101] The obtained solid BYLC-070 was analyzed by HPLC-MS, and the m / z of the product was 801 (M+).

[0102] Example 8

[0103] This embodiment provides a dichroic dye compound and its preparation method. The dichroic dye compound is designated BYLC-086 and has the following structural formula:

[0104] .

[0105] The preparation method is the same as in Example 1, except that BYLC-098-5 is replaced with BYLC-098-7 replaced with .

[0106] The obtained solid BYLC-086 was analyzed by HPLC-MS, and the m / z of the product was 855 (M+).

[0107] Example 9

[0108] This embodiment provides a dichroic dye compound and its preparation method. The dichroic dye compound is designated BYLC-034 and has the following structural formula:

[0109] .

[0110] The preparation method is the same as in Example 1, except that BYLC-098-7 is replaced with .

[0111] The obtained solid BYLC-34 was analyzed by HPLC-MS, and the m / z of the product was 847 (M+).

[0112] Example 10

[0113] This embodiment provides a dichroic dye compound and its preparation method. The dichroic dye compound is BYLC-029, and its structural formula is as follows:

[0114] .

[0115] The preparation method is the same as in Example 1, except that BYLC-098-5 is replaced with BYLC-098-7 replaced with .

[0116] The obtained solid BYLC-029 was analyzed by HPLC-MS, and the m / z of the product was 819 (M+).

[0117] Example 11

[0118] This embodiment provides a dichroic dye compound and its preparation method. The dichroic dye compound is BYLC-053, and its structural formula is as follows:

[0119] .

[0120] The preparation method is the same as in Example 1, except that BYLC-098-7, with the structural formula [missing information], is used. .

[0121] The obtained solid BYLC-053 was analyzed by HPLC-MS, and the m / z of the product was 736 (M+).

[0122] Comparative Example 1

[0123] A dichroic dye compound, denoted as CP-1, was synthesized based on literature, and its structural formula is as follows:

[0124] .

[0125] Performance testing

[0126] This test case provides the performance of the dyes in each example and comparative example, as detailed below:

[0127] The dyes provided in the various embodiments and comparative examples were mixed with liquid crystal material BLC-2510 (at a mass ratio of 1:100) to obtain liquid crystal compositions.

[0128] The structural formulas and weight proportions of each component of the liquid crystal material BLC-2510 are shown in Table 1.

[0129]

[0130] (1) Test method for order parameter S: The order parameter S of the liquid crystal composition was tested using a UV730 spectrophotometer. The wavelength at which the light transmittance is lowest is its characteristic wavelength λ. The parallel light transmittance at this wavelength is T. ∥ Vertical light transmittance is T ⊥ Substituting the transmittance in each direction into the Lambert-Beer law A=-lg T, we obtain the absorbance A in both parallel and perpendicular light directions. ∥ A ⊥ The ordered parameter is S=(A ∥ -A ⊥ ) / (A ∥ +2A ⊥ ).

[0131]

[0132] As can be seen from Table 2, compared with the existing compound CP-1, the compound provided in the embodiments of the present invention has a larger order parameter, which enables the liquid crystal display device to have better contrast, faster response speed and lower dispersion.

[0133] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0134] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dichroic dye compound, characterized in that, The dichroic dye compound has the structure shown in Formula I: Equation I; R1 is selected from H, or any one of straight-chain or branched alkyl groups with 1 to 10 carbon atoms; R2 is selected from any one of H, F, N(R3)2, F-substituted or unsubstituted alkyl group with 1 to 10 carbon atoms, F-substituted or unsubstituted alkoxy group with 1 to 10 carbon atoms, F-substituted or unsubstituted alkenyl group with 2 to 10 carbon atoms, and cycloalkyl group with 3 to 5 carbon atoms; R3 is selected from any one of the following: alkyl groups with 1 to 10 carbon atoms that are F-substituted or unsubstituted, alkenyl groups with 2 to 10 carbon atoms that are F-substituted or unsubstituted, and cycloalkyl groups with 3 to 5 carbon atoms; X1 and X2 are each independently H, CH3, C2H5, C3H7, C4H9, CH2CH(CH3)2, F or Cl; A1 and A2 are independently selected from direct bonds or at least one of the following structures: 、 、 、 、 、 ； A3 and A4 are independently selected from direct bonds or at least one of the following structures: 、 、 、 、 、 、 、 、 、 、 、 、 ； *—、—* represent the connecting bonds of functional groups; Z1 and Z2 are each independently selected from any one of the following: single bond, -CH2-, -CH2CH2-, -CH2O-, -N=N-, or -CF2O-; a and b are 1 or 2.

2. The dichroic dye compound according to claim 1 or 2, characterized in that, Compounds having the structure shown in Formula I are selected from any one or more of the following compounds:

3. A liquid crystal composition, characterized in that, The liquid crystal composition comprises any one or more of the dichroic dye compounds described in claim 1 or 2.

4. The liquid crystal composition according to claim 3, characterized in that, The liquid crystal composition further includes a host material, which comprises any one or more of the following compounds: ； Among them, R6, R7, R8, R9, R 10 R 11 R 12 Each is independently selected from any one of H, F, N(R5)2, F-substituted or unsubstituted alkyl group of 1 to 10 carbon atoms, F-substituted or unsubstituted alkoxy group of 1 to 10 carbon atoms, F-substituted or unsubstituted alkenyl group of 2 to 10 carbon atoms, and cycloalkyl group of 3 to 5 carbon atoms; R5 is selected from any one of the following: alkyl groups with 1 to 10 carbon atoms that are F-substituted or unsubstituted; alkenyl groups with 2 to 10 carbon atoms that are F-substituted or unsubstituted; and cycloalkyl groups with 3 to 5 carbon atoms.

5. The liquid crystal composition according to claim 3 or 4, characterized in that, The content of the dichroic dye compound is 0.1-15% based on the total mass of the liquid crystal composition as 100%.

6. The liquid crystal composition according to claim 5, characterized in that, The content of the dichroic dye compound is 0.1-10% based on the total mass of the liquid crystal composition (100%).

7. The use of the dichroic dye compound according to any one of claims 1-4 or the liquid crystal composition according to any one of claims 5-6 in a liquid crystal display device.

8. The application according to claim 7, characterized in that, The liquid crystal display device includes VA liquid crystal display, TN liquid crystal display, STN liquid crystal display, FFS liquid crystal display, IPS liquid crystal display, automotive instrument panel, and smart window.

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