Azo dye liquid crystal compound and liquid crystal composition

Abstract

The invention discloses an azo dye liquid crystal compound, a liquid crystal composition containing the azo dye liquid crystal compound and application. The structural formula of the azo dye liquid crystal compound is shown in the following formula I. The dye liquid crystal compound has a high dichroic ratio and good intersolubility with a liquid crystal composition. The liquid crystal composition containing the dye liquid crystal compound shown in the formula I can be used for manufacturing liquid crystal display elements or liquid crystal displays such as dimming films and dimming glass. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the technical field of display materials, and in particular to an azo dye liquid crystal compound, a liquid crystal composition containing the azo dye liquid crystal compound, and their applications in a dimming film, a dimming glass, and a liquid crystal display element. Background Art

[0002] With the rapid development of the electronics industry, the requirements for display technologies of electronic devices are becoming increasingly strict. In recent years, due to the advantages of thin thickness, low driving voltage, and low power consumption, liquid crystal displays have been widely used in the fields of thin and flat displays. Therefore, liquid crystal displays have become the mainstream display devices.

[0003] A liquid crystal display panel is a passive device that does not emit light by itself. Its display technology involves sandwiching a liquid crystal medium between two parallel glass substrates and using voltage changes on both sides of the glass substrates to change the orientation of liquid crystal molecules. The liquid crystal molecules then control the brightness of the light emitted by the backlight module to generate corresponding images. However, currently, the display functions of most liquid crystal devices mainly use polarizers, which greatly reduce the light utilization efficiency and thus degrade the performance of liquid crystal display technologies.

[0004] To avoid the influence of the polarizer on the light utilization rate in liquid crystal display technology, guest-host liquid crystal devices have attracted wide attention. Light-emitting display can be achieved in a non-backlight reflective device structure. Guest-host liquid crystals are composed of a dichroic dye (guest) dissolved in a liquid crystal (host). During the display process, the dye absorbs visible light of different wavelengths, causing the liquid crystal device to display different colors. Dichroic dyes are usually rod-shaped, and visible light has different absorption effects in the directions of its long axis and short axis, resulting in the optical anisotropy of the dye. When the vibration direction of the incident light is consistent with the long axis direction of the dye molecule, the incident light is absorbed; conversely, when the vibration direction of the incident light is consistent with the short axis direction of the dye molecule, the incident light can pass through. When the orientation of liquid crystal molecules changes with the electric field in the device, the dye molecules are driven to change accordingly, and then the angle between the dye and the incident light also changes, ultimately realizing the absorption and transmission of light by the device. Currently, the commonly used dichroic dyes in the existing technology are azo dyes and anthraquinone dyes. Among them, azo dyes are widely used in liquid crystal display devices due to their many color types, rich colors, and high brightness. The application of this dye in liquid crystals mainly changes the molecular structure of the dye by introducing liquid crystal segments, and then the liquid crystal display shows many optoelectronic properties. Further research on these optoelectronic properties is beneficial to improving the quality and performance of liquid crystal displays. However, currently, azo dyes in the existing technology mainly have the defects of low dichroic ratio and poor solubility in liquid crystal materials. Their solubility is generally 0.5 wt%, and the dichroic ratio is generally 3. The higher the dichroic ratio and solubility of azo dyes in the liquid crystal medium, the higher the contrast of the liquid crystal display device, the better the display effect, and the lower the power consumption. Therefore, developing an azo dye with a high dichroic ratio and high solubility is crucial for liquid crystal display technology. Summary of the Invention

[0005] The present invention provides an azo dye, which solves the problems of low dichroic ratio and poor solubility of azo dyes in the liquid crystal composition in the prior art. The liquid crystal composition containing the azo dye liquid crystal compound can be used to manufacture products such as dimming films, dimming glasses, and liquid crystal display elements.

[0006] To achieve the above invention object, the present invention adopts the following technical solutions:

[0007] The present invention provides an azo dye liquid crystal compound, and the structural general formula of the compound is shown in Formula I,

[0008]

[0009] Wherein,

[0010] Each independently represents a benzene ring or a naphthalene ring;

[0011] L1, L2, L3, and L4 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, a haloalkyl group having 1 to 15 carbon atoms, or a haloalkoxy group having 1 to 15 carbon atoms;

[0012] R1, R2, R3, and R4 each independently represent a single bond or an alkyl group having 1 to 15 carbon atoms, and one or more H atoms in the alkyl group are optionally substituted by a halogen, and / or any one or more of -CH2- in the alkyl group are each independently optionally substituted by -C≡C-, -CH=CH-, -O-, -S-, -CO-O-, or -O-CO- in such a way that O or S atoms are not directly connected to each other;

[0013] Z1 and Z2 each independently represent -N-, -O-, or -S-;

[0014] When Z1 represents -N-, n represents 1; when Z1 represents -O- or -S-, n represents 0;

[0015] When Z2 represents -N-, m represents 1; when Z2 represents -O- or -S-, m represents 0. Description of the Drawings

[0016] Figure 1 Are the transmittance curves of the dye liquid crystal compounds D1 and I-1-1-5 at 0V and 10V at different wavelengths in the host liquid crystal 1.

[0017] Figure 2 Are the dichroic ratios of the dye liquid crystal compounds D1 and I-1-1-5 at different wavelengths in the host liquid crystal 1. Detailed Description of the Invention

[0018] The present invention provides an azo dye liquid crystal compound, and the structural general formula of the compound is shown in Formula I,

[0019]

[0020] Wherein,

[0021] Each independently represents a benzene ring or a naphthalene ring;

[0022] L1, L2, L3, and L4 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, a haloalkyl group having 1 to 15 carbon atoms, or a haloalkoxy group having 1 to 15 carbon atoms;

[0023] R1, R2, R3, and R4 each independently represent a single bond or an alkyl group having 1 to 15 carbon atoms, and one or more H atoms in the alkyl group are optionally substituted by a halogen, and / or any one or more of -CH2- in the alkyl group are optionally independently substituted by -C≡C-, -CH=CH-, -O-, -S-, -CO-O-, or -O-CO- in such a way that O or S atoms do not directly connect to each other;

[0024] Z1 and Z2 each independently represent -N-, -O-, or -S-;

[0025] When Z1 represents -N-, n represents 1; when Z1 represents -O- or -S-, n represents 0;

[0026] When Z2 represents -N-, m represents 1; when Z2 represents -O- or -S-, m represents 0.

[0027] The azo dye liquid crystal compound of the present invention, preferably, the compound shown in the foregoing formula I is selected from the group consisting of the compounds shown in the following formulae I-1 to I-3,

[0028]

[0029] wherein,

[0030] each independently represents a benzene ring or a naphthalene ring;

[0031] L1, L2, L3, and L4 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, a haloalkyl group having 1 to 15 carbon atoms, or a haloalkoxy group having 1 to 15 carbon atoms;

[0032] R1, R2, R3, and R4 each independently represent a single bond or an alkyl group having 1 to 15 carbon atoms, and one or more H atoms in the alkyl group are optionally substituted by a halogen, and / or any one or more of -CH2- in the alkyl group are optionally independently substituted by -C≡C-, -CH=CH-, -O-, -S-, -CO-O-, or -O-CO- in such a way that O or S atoms do not directly connect to each other;

[0033] Z1 and Z2 each independently represent -N-, -O-, or -S-;

[0034] When Z1 represents -N-, n represents 1; when Z1 represents -O- or -S-, n represents 0;

[0035] When Z2 represents -N-, m represents 1; when Z2 represents -O- or -S-, m represents 0.

[0036] The azo dye liquid crystal compound of the present invention, preferably, the compounds represented by the foregoing Formulas I-1 to I-3 are selected from the group consisting of the compounds represented by the following Formulas I-1-1 to I-3-1,

[0037]

[0038] wherein,

[0039] L1, L2, L3, and L4 each independently represent a hydrogen atom, a halogen atom, a linear alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, a haloalkyl group having 1 to 15 carbon atoms, or a haloalkoxy group having 1 to 15 carbon atoms;

[0040] R1, R2, R3, and R4 each independently represent a single bond or a linear alkyl group having 1 to 15 carbon atoms, and one or more H atoms in the linear alkyl group are optionally substituted by a halogen, and / or any one or more of -CH2- in the linear alkyl group are each independently optionally substituted by -C≡C-, -CH=CH-, -O-, -S-, -CO-O-, or -O-CO- in such a manner that O or S atoms are not directly connected to each other;

[0041] Z1 and Z2 each independently represent -N-, -O-, or -S-;

[0042] When Z1 represents -N-, n represents 1; when Z1 represents -O- or -S-, n represents 0;

[0043] When Z2 represents -N-, m represents 1; when Z2 represents -O- or -S-, m represents 0.

[0044] The azo dye liquid crystal compound of the present invention, preferably, the compounds represented by the foregoing Formulas I-1-1 to I-2-1 are selected from any one or any combination of the following compounds represented by Formulas I-1-1-1 to I-2-1-4,

[0045]

[0046]

[0047]

[0048]

[0049]

[0050] The present invention provides a liquid crystal composition, which comprises at least one of the foregoing azo dye liquid crystal compounds and at least one liquid crystal compound having a neutral dielectric anisotropy.

[0051] The liquid crystal composition of the present invention. Preferably, the aforementioned liquid crystal composition contains one or more compounds represented by Formula II,

[0052]

[0053] wherein,

[0054] R5 and R6 each independently represent a straight-chain alkyl or branched-chain alkyl having 1 to 15 carbon atoms, a straight-chain alkoxy or branched-chain alkoxy having 1 to 15 carbon atoms, a straight-chain alkenyl or branched-chain alkenyl having 2 to 15 carbon atoms, or a straight-chain alkenyloxy or branched-chain alkenyloxy having 3 to 15 carbon atoms;

[0055] Z3 represents a single bond, -C≡C-, -CH2-O-, or -COO-;

[0056] r and e each independently represent 1, 2, or 3;

[0057] each independently represents and when r represents 2 or 3, two or three are optionally the same or different.

[0058] The liquid crystal composition of the present invention. Preferably, the compound represented by Formula II is selected from the group consisting of compounds represented by the following Formula II-1 to II-32,

[0059]

[0060]

[0061]

[0062] The liquid crystal composition of the present invention. Preferably, the aforementioned liquid crystal composition further contains one or more compounds represented by Formula III,

[0063]

[0064] wherein,

[0065] R7 represents a straight-chain alkyl or branched-chain alkyl having 1 to 15 carbon atoms, a straight-chain alkoxy or branched-chain alkoxy having 1 to 15 carbon atoms, a straight-chain alkenyl or branched-chain alkenyl having 2 to 15 carbon atoms, or a straight-chain alkenyloxy or branched-chain alkenyloxy having 3 to 15 carbon atoms;

[0066] R8 represents -F, -C≡C, -CF3, -OCF3, or CN;

[0067] Z4 represents a single bond, -CF2O-, -CH2O-, or -COO-;

[0068] a and b each independently represent 1 or 2;

[0069] each independently represent and when a or b represents 2, the two each independently are the same or different.

[0070] For the liquid crystal composition of the present invention, preferably, the compound represented by the foregoing formula III is selected from the group consisting of the compounds represented by the following formulae III-1 to III-38,

[0071]

[0072]

[0073]

[0074] wherein, R7 represents a linear alkyl or branched alkyl having 1 to 15 carbon atoms, a linear alkoxy or branched alkoxy having 1 to 15 carbon atoms, a linear alkenyl or branched alkenyl having 2 to 15 carbon atoms, or a linear alkenyloxy or branched alkenyloxy having 3 to 15 carbon atoms.

[0075] For the liquid crystal composition of the present invention, preferably, the foregoing liquid crystal composition further comprises one or more compounds represented by formula IV,

[0076]

[0077] wherein, R9, R 10 each independently represent a linear alkyl or branched alkyl having 1 to 15 carbon atoms, a linear alkoxy or branched alkoxy having 1 to 15 carbon atoms, a linear alkenyl or branched alkenyl having 2 to 15 carbon atoms, or a linear alkenyloxy or branched alkenyloxy having 3 to 15 carbon atoms;

[0078] Z5 represents a single bond, -CF2O-, -CH2O-, -CH=CH-, -C≡C- or -CH2CH2-;

[0079] c and d each independently represent 0, 1 or 2;

[0080] each independently represent and when c or d represents 2, the two each independently may be the same or different.

[0081] For the liquid crystal composition of the present invention, preferably, the compound represented by the foregoing formula IV is selected from the group consisting of the compounds represented by the following formulae IV-1 to IV-11,

[0082]

[0083] Among them, R9, R 10 each independently represents a straight-chain alkyl or branched-chain alkyl having 1 to 15 carbon atoms, a straight-chain alkoxy or branched-chain alkoxy having 1 to 15 carbon atoms, a straight-chain alkenyl or branched-chain alkenyl having 2 to 15 carbon atoms, or a straight-chain alkenyloxy or branched-chain alkenyloxy having 3 to 15 carbon atoms.

[0084] For the liquid crystal composition of the present invention, preferably, the mass content of the aforementioned azo dye liquid crystal compound is added based on the total mass content of 100% of the liquid crystal composition, and the addition amount is 0.3 - 5%.

[0085] The present invention also provides a dimming film, which comprises at least one of the aforementioned azo dye liquid crystal compounds, or at least one of the aforementioned liquid crystal compositions.

[0086] The present invention also provides a dimming glass, which comprises at least one of the aforementioned azo dye liquid crystal compounds, or at least one of the aforementioned liquid crystal compositions.

[0087] The present invention also provides a liquid crystal display element, which comprises at least one of the aforementioned azo dye liquid crystal compounds, or at least one of the aforementioned liquid crystal compositions; preferably, the liquid crystal display element is a guest-host liquid crystal display element.

[0088] The present invention also provides a liquid crystal display, which comprises at least one of the aforementioned azo dye liquid crystal compounds, or at least one of the aforementioned liquid crystal compositions; preferably, the liquid crystal display is a guest-host liquid crystal display.

[0089] Beneficial effects:

[0090] 1. The azo dye provided by the present invention is red, and its maximum absorption wavelength range is 480 nm - 550 nm. It has the characteristics of high light stability, high dichroic ratio, and high compatibility with liquid crystal materials (the addition amount of this dichroic dye in the liquid crystal composition is 0.5 - 5%, preferably 0.5 - 3.5%, and no precipitation occurs after being placed in a glove box at -20°C for 10 days); among them, placing the biphenyl structure in the middle of the compound structure has a better aspect ratio and better linear relationship than placing the biphenyl structure near the two ends. At the same time, the molecular structure of the liquid crystal compound is more regular. Therefore, the azo dye liquid crystal compound of the present invention has a better dichroic ratio and better low-temperature miscibility.

[0091] 2. The liquid crystal composition containing the azo dye of formula I provided by the present invention shows colorless under the condition of energization in different matrix liquid crystals, with high light transmittance (the visible light transmittance under the condition of 10V energization reaches 26%-33%), shows red after power-off, and has low light transmittance (the visible light transmittance under the condition of 0V energization reaches 2.6%-3.6%). It can be used to manufacture products such as dimming films, dimming glasses, liquid crystal display elements or liquid crystal displays.

[0092] Example

[0093] To illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention. The examples and comparative examples in this specification are provided to more completely illustrate this specification to those skilled in the art. According to the examples and comparative examples in this specification, various different forms can be deformed, and the protection scope of the present invention should not be limited only to the embodiments and comparative examples described in detail below.

[0094] For the preparation method of the compound shown in the foregoing formula I of the present invention, the following synthetic route is preferably adopted, and other similar structures can also use such methods.

[0095]

[0096] Example 1

[0097] This example provides a liquid crystal compound I-1-1-1, and the structure and synthetic route are as follows:

[0098]

[0099] Step 1

[0100] Add N-methylaniline (25 g, 0.234 mmol), bromohexane (58 g, 0.35 mmol), and potassium carbonate (97 g, 0.7 mmol) to a 500 ml three-necked flask. Then add 200 ml of DMF to the flask. After replacing the nitrogen three times, heat to 110 °C and heat for 24 hours. Then cool to room temperature. Pour the reaction solution into 500 ml of ice water, extract with ethyl acetate, dry, and concentrate to obtain a yellow oily intermediate 1 (25 g, 56%).

[0101] Step 2

[0102] Solution A: Add 200 ml of water, 25 ml of 3N hydrochloric acid, and p-bromoaniline (25 g, 0.132 mmol) to a 500 ml three-necked flask. After cooling the system to 0 °C, add sodium nitrite (9.3 g, 0.134 mmol), and stir at a constant temperature for 1 hour.

[0103] Solution B: Add 100 ml of ethanol, 50 ml of water, and Intermediate 1 (25 g, 0.132 mmol) to a 1 L three-necked flask, and cool the system to 0 °C.

[0104] Add Solution A to Solution B within 20 min, control the temperature at 0 °C and stir for 1 h. Then add 500 ml of water and 300 ml of ethyl acetate to the system, stir and separate the layers. Extract the reaction solution with ethyl acetate, dry the organic phase, concentrate, and purify by silica gel column chromatography (petroleum ether: ethyl acetate = 15:1) to obtain Intermediate 2 (13 g, 25%).

[0105] Step 3

[0106] Add Intermediate 2 (20 g, 0.051 mmol), pinacolborane (6.5 g, 0.0254 mmol), potassium carbonate (8.4 g, 0.061 mmol), tetrakis(triphenylphosphine)palladium(0) (0.03 g, 0.00002 mmol), and toluene (30 ml) to a 250 ml three-necked flask, then protect with nitrogen and reflux for 3 h. Cool to room temperature, add 100 ml of water to the reaction, separate the layers, pass the toluene phase through a silica gel column, concentrate, obtain 15 g of an oily substance, mix with silica gel for sample preparation and then pass through a silica gel column (petroleum ether: ethyl acetate = 20:1) to obtain I-1-1-1 (4.3 g, 51%). MS (m / z) (M+): 588.39

[0107] Example 2

[0108] This example provides a liquid crystal compound I-1-1-2, and its structural formula is as follows

[0109]

[0110] The synthetic route of this compound is as follows:

[0111]

[0112] The specific synthesis method is the same as that of Compound Example 1, except that N-methylaniline is replaced by aniline, and finally the product I-1-1-2 (3.5 g, yield 38%) is obtained. MS (m / z) (M+): 728.55.

[0113] Example 3

[0114] This example provides a liquid crystal compound I-1-1-5, and its structural formula is as follows:

[0115]

[0116] The synthetic route of this compound is as follows:

[0117]

[0118] The specific synthesis method is the same as that of Compound Example 1, except that p-bromoaniline is replaced by o-fluoro-p-bromoaniline, and finally the product I-1-1-5 (2.4 g, yield 33%) is obtained, MS (m / z) (M+): 624.38.

[0119] Example 4

[0120] This example provides a liquid crystal compound I-1-1-6, and its structural formula is as follows:

[0121]

[0122] The synthesis route of this compound is as follows:

[0123]

[0124] The specific synthesis method is the same as that of Compound Example 1, except that p-bromoaniline is replaced by o-fluoro-p-bromoaniline and N-methylaniline is replaced by aniline, and finally the product I-1-1-6 (3.9 g, yield 33%) is obtained, MS (m / z) (M+): 764.53.

[0125] Example 5

[0126] This example provides a liquid crystal compound I-1-1-8, and its structural formula is as follows:

[0127]

[0128] The synthesis route of this compound is as follows:

[0129]

[0130] The specific synthesis method is the same as that of Compound Example 1, except that bromohexane is replaced by ethyl bromovalerate, and finally the product I-1-1-8 (5.1 g, yield 42%) is obtained, MS (m / z) (M+): 676.37.

[0131] Example 6

[0132] This example provides a liquid crystal compound I-1-1-12, and its structural formula is as follows:

[0133]

[0134] The synthesis route of this compound is as follows:

[0135]

[0136] The specific synthesis method is the same as that of Compound Example 1, except that bromohexane is replaced by ethyl bromovalerate and p-bromoaniline is replaced by 2-fluoro-4-bromoaniline, and finally Product I-1-1-12 (4.5 g, yield 47%) is obtained. MS (m / z) (M+): 712.35.

[0137] Example 7

[0138] This example provides a liquid crystal compound I-1-1-13, and its structural formula is as follows:

[0139]

[0140] The synthetic route of this compound is as follows:

[0141]

[0142] Step 1

[0143] Add phenol (20 g, 0.21 mmol), ethyl bromovalerate (48 g, 0.23 mmol), potassium carbonate (43 g, 0.315 mmol), and DMF (200 ml) to 250 ml, heat to 120 °C for reaction. After reacting for 4 hours, pour the reaction solution into ice water, extract with ethyl acetate, dry, concentrate, obtain a crude yellow oil product, and purify it by silica gel column chromatography with ethyl acetate: petroleum ether (10:1) to obtain Intermediate 1 (44 g, 94%).

[0144] Step 2

[0145] Solution A: Add 200 ml of water, 25 ml of 3N hydrochloric acid, and 2-fluoro-4-bromoaniline (15 g, 0.08 mmol) to a 500 ml three-necked flask. After cooling the system to 0 °C, add sodium nitrite (5.5 g, 0.08 mmol), and keep stirring at this temperature for 1 hour.

[0146] Solution B: Add 100 ml of ethanol, 50 ml of water, and Intermediate 1 (17.7 g, 0.08 mmol) to a 1 L three-necked flask, and cool the system to 0 °C.

[0147] Add Solution A to Solution B within 20 min, keep stirring at 0 °C for 1 hour, then add 500 ml of water and 300 ml of ethyl acetate to the system, stir and separate the layers, extract the reaction solution with ethyl acetate, dry the organic phase, concentrate, and purify it by silica gel column chromatography (petroleum ether: ethyl acetate 15:1) to obtain Intermediate 2 (18 g, 33%).

[0148] Step 3

[0149] Add intermediate 2 (18 g, 0.026 mmol), pinacolborane (3.3 g, 0.013 mmol), potassium carbonate (11 g, 0.078 mmol), tetrakis(triphenylphosphine)palladium(0) (0.015 g, 0.000013 mmol), and toluene (30 ml) into a 250 ml three-necked flask. Under nitrogen protection, heat under reflux for 3 hours, cool to room temperature, add 100 ml of water to the reaction, separate the layers, pass the toluene phase through a silica gel column, concentrate, obtain 15 g of an oily substance, mix with silica gel for sample loading and then pass through a silica gel column (petroleum ether:ethyl acetate = 20:1) to obtain I-1-1-13 (5.2 g, 41%). MS (m / z) (M+): 686.29

[0150] Example 8

[0151] This example provides a liquid crystal compound I-1-1-9, and its structural formula is as follows:

[0152]

[0153] The synthesis route of this compound is as follows:

[0154]

[0155] The specific synthesis method is the same as that of Compound Example 7, except that o-fluoro-p-bromoaniline is replaced with p-bromoaniline, and finally the product I-1-1-9 (6.3 g, yield 56%) is obtained. MS (m / z) (M+): 650.31.

[0156] Example 9

[0157] This example provides a liquid crystal compound I-1-1-15, and its structural formula is as follows:

[0158]

[0159] The synthesis route of this compound is as follows:

[0160]

[0161] The specific synthesis method is the same as that of Compound Example 7, except that ethyl bromovalerate is replaced with bromohexane, and finally the product I-1-9 (6.2 g, yield 58%) is obtained. MS (m / z) (M+): 598.31.

[0162] Example 10

[0163] This example provides a liquid crystal compound I-2-1-1, and its structural formula is as follows

[0164]

[0165] The synthesis route of this compound is as follows:

[0166]

[0167] The specific synthesis method is the same as that of Compound Example 1, except that 1-naphthylamine is replaced by 4-bromo-1-naphthylamine, and Intermediate 2 of this batch of compounds is coupled with Intermediate 2 of Example 1 under the reaction conditions of Example 1, and finally Product I-2-1-1 (2.3 g, yield 25%) is obtained, MS (m / z) (M+): 638.14.

[0168] Example 11

[0169] This example provides a liquid crystal compound I-2-1-2, and its structural formula is as follows

[0170]

[0171] The synthesis route of this compound is as follows:

[0172]

[0173] The specific synthesis method is the same as that of Compound Example 2, except that p-bromoaniline is replaced by 4-bromo-1-naphthylamine, and Intermediate 2 of this batch of compounds is coupled with Intermediate 2 of Example 2 under the reaction conditions of Example 1, and finally Product I-2-1-2 (2.1 g, yield 23%) is obtained, MS (m / z) (M+): 778.57.

[0174] Table 1 Corresponding codes of ring structures

[0175]

[0176]

[0177] Table 2 Corresponding codes of end groups and linking groups

[0178]

[0179]

[0180] For example:

[0181] Its code is CC-Cp-V1;

[0182] Its code is PGP-Cpr1-2;

[0183] Its code is CPY-2-O2;

[0184] Its code is CCY-3-O2;

[0185] Its code is COY-3-O2;

[0186] Its code is CCOY-3-O2; Its code is Sb-CpO-O4;

[0187] Its code is Sc-CpO-O4;

[0188] Its code is CCU-3-F;

[0189] Its code is PGU-3-F;

[0190] Its code is CCPU-3-F;

[0191] Its code is CPGU-3-OT; Its code is DGUQU-4-F;

[0192] Its code is PGUQU-3-F;

[0193] Its code is PPGU-Cp-F.

[0194] Application Example

[0195] Dye liquid crystal compounds for comparison:

[0196]

[0197] Table 3 Matrix Liquid Crystal 1

[0198]

[0199]

[0200] Table 4 Matrix Liquid Crystal 2

[0201] Structure Ratio Ⅲ CC-3-5 10 Ⅳ CPY-3-O2 5 Ⅳ CCOY-3-O2 27 Ⅳ CCOY-3-O2 4 Ⅳ CCY-2-O2 8 Ⅳ CCY-4-O2 2 Ⅳ CPY-2-O2 11 Ⅳ CY-V-O2 8 Ⅳ YZY-2O-O2 13 Ⅳ PYQY-2-3 3 Ⅳ PTY-3-O2 9

[0202] Table 5 Matrix Liquid Crystal 3

[0203] Structure Ratio Ⅳ CCOY-3-O2 30 Ⅱ CCP-V-1 11 Ⅱ CC-3-V 16.5 Ⅳ CY-3-O2 7.5 Ⅳ CCY-3-O2 7.47 Ⅳ CCY-2-O2 2 Ⅳ CPY-2-O2 10 Ⅳ CY-V-O2 6 Ⅳ YZY-2O-O2 9 Ⅳ PYQY-2-3 0.5 Ⅳ PTY-3-O2 0.03

[0204] Table 6 Matrix Liquid Crystal 4

[0205]

[0206]

[0207] Dichroic contrast test

[0208] To be closer to the actual working conditions of the dye, dye I-1-1-5 was added to the matrix liquid crystal 1 as a test sample. At the same time, dye D1 was added to the same matrix liquid crystal as a control sample. The addition amounts of both I-1-1-5 and D1 were 0.5%. After heating and stirring at 120 °C for 1 h, a TN-7.0 test cell was used for spotting, and the transmittance spectra at 400 - 800 nm were sent for DMS test at 0 V and 10 V voltages to obtain the transmittances at 0 V and 10 V at each wavelength. From Figure 1 it can be seen that the maximum absorption wavelengths of D1 and I-1-1-5 are in the range of 500 - 520 nm, and the absorption of I-1-1-5 at 0 V is significantly lower than that of D1. The dichroic contrast = transmittance at 10 V / transmittance at 0 V, and the dichroic contrast at each wavelength was calculated. From Figure 2 it can be seen that near the wavelength of 500 nm, the dichroic ratio of I-1-1-5 is 10, and the dichroic ratio of D1 is 3.15. The dichroic ratio of I-1-1-5 is significantly higher than that of D1;

[0209] Similarly, the dichroic ratios of D2, D3, I-1-1-1, I-1-1-2, I-1-1-5, I-1-1-6, I-1-1-8, I-1-1-9, I-1-1-12, I-1-1-13, I-1-1-15, I-2-1-1, and I-2-1-2 in matrix liquid crystal 1 were tested; and the dichroic ratios of D1, D2, D3, I-1-1-1, I-1-1-2, I-1-1-5, I-1-1-6, I-1-1-8, I-1-1-9, I-1-1-12, I-1-1-13, I-1-1-15, I-2-1-1, and I-2-1-2 in matrix liquid crystals 2, 3, and 4 were tested. The specific data are as follows:

[0210] Table 7 Dichroic ratio data in different matrix liquid crystals

[0211]

[0212] As can be seen from Table 7, the dichroic ratio of the azo dye of formula I of the present invention in the matrix liquid crystal is better than that of the control samples D1, D2, and D3. This means that the contrast of the liquid crystal composition containing the azo dye of formula I in matrix liquid crystal 1 has a greater improvement compared to the control samples, and it is more suitable for manufacturing products such as dimming films, dimming glasses, liquid crystal display elements, or liquid crystal displays.

[0213] Solubility test

[0214] After adding D1, D2, D3, Ⅰ-1-1-1, Ⅰ-1-1-2, Ⅰ-1-1-5, Ⅰ-1-1-6, Ⅰ-1-1-8, Ⅰ-1-1-9, Ⅰ-1-1-12, Ⅰ-1-1-13, Ⅰ-1-1-15, Ⅰ-2-1-1, and Ⅰ-2-1-2 to different host liquid crystals at different concentrations (0.5 - 5 wt%), they were mixed and stirred evenly in a glass bottle, stored at -20°C, and observed daily for crystal precipitation. The results are shown in the following table:

[0215] Table 8 Low-temperature experimental data in host liquid crystal 1

[0216]

[0217] Table 9 Low-temperature experimental data in host liquid crystal 2

[0218]

[0219]

[0220] Table 10 Low-temperature experimental data in host liquid crystal 3

[0221]

[0222]

[0223] Table 11 Low-temperature experimental data in host liquid crystal 4

[0224]

[0225] As can be seen from Tables 8 - 11, the low-temperature solubility of the azo dye liquid crystal compound shown in Formula Ⅰ of the present invention in the liquid crystal material is significantly better than that of the comparative dye compound, meeting the requirements for long-term use at low temperatures after manufacturing products such as dimming films, dimming glasses, liquid crystal display elements, or liquid crystal displays.

[0226] The present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the appended claims of the present invention.

Claims

1. An azo dye liquid crystal compound, characterized in that, The general structural formula of the said compound is shown in Formula I, wherein, Each independently represents a benzene ring or a naphthalene ring; L1, L2, L3, and L4 each independently represent a hydrogen atom, a halogen atom, an alkyl chain with 1 - 15 carbon atoms, an alkoxy group with 1 - 15 carbon atoms, a haloalkyl group with 1 - 15 carbon atoms, or a haloalkoxy group with 1 - 15 carbon atoms; R1, R2, R3, and R4 each independently represent a single bond or an alkyl group having 1 to 15 carbon atoms, and one or more H atoms in the alkyl group are optionally substituted by halogen, and / or any one or more of -CH2- in the alkyl group are each independently optionally substituted by -C≡C-, -CH=CH-, -O-, -S-, -CO-O-, or -O-CO- in such a way that O or S atoms are not directly connected to each other; Z1 and Z2 each independently represent -N-, -O-, or -S-; When Z1 represents -N-, n represents 1; when Z1 represents -O- or -S-, n represents 0; When Z2 represents -N-, m represents 1; when Z2 represents -O- or -S-, m represents 0.

2. The azo dye liquid crystal compound according to claim 1, characterized in that, The compound shown in Formula I is selected from the group consisting of the compounds shown in the following Formulae I - 1 to I - 3, wherein, Each independently represents a benzene ring or a naphthalene ring; L1, L2, L3, and L4 each independently represent a hydrogen atom, a halogen atom, an alkyl chain with 1 to 15 carbon atoms, an alkoxy group with 1 - 15 carbon atoms, a haloalkyl group with 1 - 15 carbon atoms, or a haloalkoxy group with 1 - 15 carbon atoms; R1, R2, R3, and R4 each independently represent a single bond or an alkyl group having 1 to 15 carbon atoms, and one or more H atoms in the alkyl group are optionally substituted by a halogen, and / or any one or more of -CH2- in the alkyl group are each independently optionally substituted by -C≡C-, -CH=CH-, -O-, -S-, -CO-O-, or -O-CO- in such a way that O or S atoms are not directly connected to each other; Z1 and Z2 each independently represent -N-, -O-, or -S-; When Z1 represents -N-, n represents 1; when Z1 represents -O- or -S-, n represents 0; When Z2 represents -N-, m represents 1; when Z2 represents -O- or -S-, m represents 0.

3. The azo dye liquid crystal compound according to claim 2, characterized in that, The compounds shown in Formulae I - 1 to I - 3 are selected from the group consisting of the compounds shown in the following Formulae I - 1 - 1 to I - 3 - 1, wherein, L1, L2, L3, and L4 each independently represent a hydrogen atom, a halogen atom, an alkyl chain with 1 - 15 carbon atoms, an alkoxy group with 1 - 15 carbon atoms, a haloalkyl group with 1 - 15 carbon atoms, or a haloalkoxy group with 1 - 15 carbon atoms; R1, R2, R3, and R4 each independently represent a single bond or an alkyl group having 1 to 15 carbon atoms, and one or more H atoms in the alkyl group are optionally substituted by a halogen, and / or any one or more of -CH2- in the alkyl group are each independently optionally substituted by -C≡C-, -CH=CH-, -O-, -S-, -CO-O-, or -O-CO- in such a way that O or S atoms are not directly connected to each other; Z1 and Z2 each independently represent -N-, -O-, or -S-; When Z1 represents -N-, n represents 1; when Z1 represents -O- or -S-, n represents 0; When Z2 represents -N-, m represents 1; when Z2 represents -O- or -S-, m represents 0.

4. The azo dye liquid crystal compound according to claim 3, wherein The compounds shown in Formulae I - 1 - 1 to I - 2 - 1 are selected from any one or any combination of the following compounds shown in Formulae I - 1 - 1 - 1 to I - 2 - 1 - 4, 5. A liquid crystal composition, characterized in that, comprising at least one azo - dye liquid - crystal compound according to any one of claims 1 - 4, and at least one liquid - crystal compound with a neutral dielectric anisotropy.

6. The liquid crystal composition according to claim 5, characterized in that, The said liquid - crystal composition comprises one or more compounds shown in Formula II, wherein, R5 and R6 each independently represent a straight - chain or branched - chain alkyl group with 1 - 15 carbon atoms, a straight - chain or branched - chain alkoxy group with 1 - 15 carbon atoms, a straight - chain or branched - chain alkenyl group with 2 - 15 carbon atoms, or a straight - chain or branched - chain alkenyloxy group with 3 - 15 carbon atoms; Z3 represents a single bond, -C≡C-, -CH2 - O-, or -COO-; r and e each independently represent 1, 2, or 3; each independently represents and when r represents 2 or 3, two or three optionally the same or different.

7. The liquid crystal composition according to claim 5, characterized in that, The said liquid - crystal composition further comprises one or more compounds shown in Formula III, wherein, R7 represents a linear or branched alkyl group having 1 to 15 carbon atoms, a linear or branched alkoxy group having 1 to 15 carbon atoms, a linear or branched alkenyl group having 2 to 15 carbon atoms, or a linear or branched alkenyloxy group having 3 to 15 carbon atoms; R8 represents -F, -C≡C, -CF3, -OCF3 or CN; Z4 represents a single bond, -CF2O-, -CH2O- or -COO-; a and b each independently represent 1 or 2; Each independently represents and when a or b represents 2, the two are each independently the same or different.

8. The liquid crystal composition according to claim 5, characterized in that, The liquid crystal composition further comprises one or more compounds represented by Formula IV, wherein, R9, R 10 each independently represents a straight-chain or branched alkyl group having 1 to 15 carbon atoms, a straight-chain or branched alkoxy group having 1 to 15 carbon atoms, a straight-chain or branched alkenyl group having 2 to 15 carbon atoms, or a straight-chain or branched alkenyloxy group having 3 to 15 carbon atoms; Z5 represents a single bond, -CF2O-, -CH2O-, -CH=CH-, -C≡C- or -CH2CH2-; c and d each independently represent 0, 1 or 2; each independently represents and when c or d represents 2, the two each independently may be the same or different.

9. The liquid crystal composition according to any one of claims 5-8, characterized in that, The mass content of the azo dye liquid crystal compound is added based on the total mass content of 100% of the liquid crystal composition, and the addition amount is 0.3-5%.

10. A dimming film, characterized in that, The dimming film comprises at least one azo dye liquid crystal compound according to any one of claims 1-4, or at least one liquid crystal composition according to any one of claims 5-8.

11. A liquid crystal display element, characterized in that, The liquid crystal display element comprises at least one azo dye liquid crystal compound according to any one of claims 1-4, or at least one liquid crystal composition according to any one of claims 5-8.

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