Dichroic dye, liquid crystal composition and application thereof

Abstract

The invention discloses a dichroic dye, a liquid crystal composition and application of the dichroic dye and the liquid crystal composition. The structural formula of the dichroic dye is shown in the formula I in the specification. A hydrogenated quinoline ring, a hydrogenated benzopyran ring and a hydrogenated naphthalene ring are introduced into a molecular skeleton, so that the novel dichroic dye with high light stability, high solubility, high dichroic ratio and high light modulation capability is obtained. The liquid crystal composition and the dimming glass device prepared from the dichroic dye have the advantages of high photo-thermal stability, high order parameter, wide working temperature area and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of liquid crystal materials, and relates to a dichroic dye with high stability, high solubility and high order parameter, a synthesis method of the dichroic dye, a liquid crystal composition containing the dichroic dye, and a light-adjusting glass device, a polaroid and a use. BACKGROUND

[0002] The light-adjusting glass can realize controllable adjustment of ultraviolet light, visible light and even infrared light waves, and has a wide application prospect in building lighting glass, automobile windows and the like. Through the regulation of input light and heat energy by the light-adjusting glass, the energy consumption of air conditioners and the like can be reduced, and energy saving and emission reduction can be realized. Current light-adjusting glass schemes include dye liquid crystal, PDLC (polymer dispersed liquid crystal), EC (electrochromic) and SPD (suspended particle) and the like. The principle of EC (electrochromic) is to realize color change and light adjustment through oxidation-reduction reaction, but the response speed is slow (~5 min / m 2 ), and the larger the size of the glass, the slower the color change, and the more likely to appear uneven color change. The PDLC (polymer dispersed liquid crystal) light-adjusting glass is transparent when powered on and presents a fog state when powered off, and due to the large haze, the application scenarios of PDLC are limited, and it is more suitable for application in conference room partitions and the like, and is limited in application scenarios such as car window glass. The working voltage of the SPD (suspended particle) light-adjusting glass is as high as 110V, which has safety risks, and therefore its application in car window glass is greatly limited.

[0003] The light-adjusting glass based on dye liquid crystal has the advantages of stepless light adjustment and second-level response; the driving voltage is low (<12V), and the power consumption is 2w / m 2 , which is beneficial to energy saving and consumption reduction; it has high transmittance, small haze and no viewing angle problem. Therefore, the light-adjusting glass based on dye liquid crystal has significant technical advantages compared with other light-adjusting glass technologies. The working principle of the dye liquid crystal light-adjusting glass is the "guest-host mode", which is beneficial to the difference in light absorption of the long axis and the short axis of the dichroic dye molecules, and realizes the absorption and adjustment of light. The performance of the dichroic dye, especially the light stability, solubility, absorption spectrum range, anisotropy of the absorption spectrum, order parameter and the like, has a decisive influence on the performance and long-term use reliability of the dye liquid crystal light-adjusting glass device.

[0004] The dichroic dye based on the azo structure has a high order parameter, but the ultraviolet light stability of the azo dye is poor, and it is difficult to realize long-term stable application. The dichroic dye based on the benzothiadiazole mother nucleus unit disclosed in the prior art has poor solubility in the mother liquid crystal, and the application is greatly limited, which is difficult to meet the application requirements of light-adjusting glass and the like.

[0005] In summary, it is very urgent to develop dichroic dye molecules with excellent light stability, high solubility, high order parameter and high light absorption capacity, and liquid crystal compositions containing new dichroic dyes to meet the application requirements of light control glass and the like. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present application is to provide a dichroic dye, a liquid crystal composition and applications thereof, so as to obtain a dichroic dye with high light stability, high solubility, high order parameter and high light modulation capacity.

[0007] The present application provides a dichroic dye, and the structure general formula I of the dichroic dye compound is:

[0008]

[0009] In formula I:

[0010] W is an oxygen atom, a sulfur atom or a selenium atom;

[0011] X is C-L2 or a nitrogen atom;

[0012] L1, L2 are each independently selected from a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group with a carbon atom number of 1-6;

[0013] Y is 0, 1 or 2;

[0014] A1, A2 are each independently selected from the aromatic rings shown in the following structures:

[0015]

[0016] wherein L3, L4 are each independently selected from a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group, or an alkyl group with a carbon atom number of 1-7;

[0017] A3, A4 are each independently selected from the aromatic rings shown in the following structures, a hydrogenated quinoline ring, a hydrogenated benzopyran ring or a hydrogenated naphthalene ring, and at least one of A3, A4 is a hydrogenated quinoline ring, a hydrogenated benzopyran ring or a hydrogenated naphthalene ring:

[0018]

[0019]

[0020] wherein R1, R2, R3, R4, R6, R7 are each independently selected from a hydrogen atom or an alkyl group with a carbon atom number of 1-7; R5 is a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group or an ethyl group; R8 represents a hydrogen atom, an alkyl group with a carbon atom number of 1-10, an alkoxy group with a carbon atom number of 1-10, -NHR9 or -N(R9)2; R9 represents an alkyl group with a carbon atom number of 1-10.

[0021] Further, the dichroic dye preferably has a structure in which W is a sulfur atom, and A1 and A2 are each independently selected from a benzene ring, a thiophene ring, or a bithiophene ring.

[0022] Further, the dichroic dye preferably has a structure represented by any one of formulas I-1 to I-16:

[0023]

[0024]

[0025]

[0026] Further, the dichroic dye preferably has a structure represented by any one of formulas I-1 to I-16:

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033] The dichroic dye of the present application has high light stability, high solubility, high dichroic ratio, and high light modulation ability. When the dichroic dye is used in a liquid crystal composition, the light modulation ability is significantly increased, and the solubility is greatly improved, thus solving the application bottleneck.

[0034] The present application also provides a liquid crystal composition comprising the dichroic dye represented by general formula I and one or more liquid crystal compounds.

[0035] In specific embodiments, the liquid crystal composition of the present application comprises at least one dichroic dye represented by general formula I. The liquid crystal composition of the present application comprises at least one yellow or orange dye, at least one red dye, and at least one blue dye (the color of the dye of the present application is the color perceived by the eye), thereby obtaining a black mixed dye that absorbs the entire visible light band.

[0036] In further specific embodiments, the mass percentage of the dichroic dye represented by general formula I in the liquid crystal composition of the present application is 0.1 to 10%.

[0037] The monomer liquid crystal compound in the liquid crystal composition of the present application is selected from the compounds represented by the general structure II:

[0038]

[0039] In the formula II, R is an alkyl group with 1-10 carbon atoms, an alkoxy group with 1-10 carbon atoms, an alkenyl group with 2-10 carbon atoms, or a cycloalkyl group with 3-6 carbon atoms; ring A, ring B, and ring C are independently selected from cyclohexane, cyclohexene, benzene ring, tetrahydropyran ring, or benzene ring with hydrogen atom replaced by fluorine; X0 is hydrogen, fluorine, chlorine, cyano, trifluoromethoxy, trifluoromethyl, alkyl group with 1-10 carbon atoms, alkoxy group with 1-10 carbon atoms, alkenyl group with 2-10 carbon atoms, or cycloalkyl group with 3-6 carbon atoms; X1, X2, and X3 are independently hydrogen or fluorine; X4 is a single bond, -COO-, -CH2CH2-, or -CF2O-; k, p, and q are independently 0, 1, or 2, and k+p+q≥1.

[0040] Preferably, the monomer liquid crystal compound of the general structure II is selected from the following structures:

[0041]

[0042]

[0043]

[0044] In the above structures, m is a natural number in the range of 1-10, and n is in the range of 1-10.

[0045] The monomer liquid crystal compound in the liquid crystal composition of the present application can also be selected from or partially selected from the compounds represented by the general structure III:

[0046]

[0047] In the formula III, R' is an alkyl group with 1-10 carbon atoms, an alkoxy group with 1-10 carbon atoms, an alkenyl group with 2-10 carbon atoms, or a cycloalkyl group with 3-6 carbon atoms; ring A is cyclohexane, cyclohexene, benzene ring, tetrahydropyran ring, or benzene ring with hydrogen atom replaced by fluorine; X0' is hydrogen, fluorine, chlorine, cyano, trifluoromethoxy, trifluoromethyl, alkyl group with 1-10 carbon atoms, alkoxy group with 1-10 carbon atoms, alkenyl group with 2-10 carbon atoms, or cycloalkyl group with 3-6 carbon atoms; X4' is a single bond, -COO-, -CH2CH2-, -CF2O-, or -CH2O-; X5' is oxygen atom or sulfur atom; and k is 0, 1, or 2.

[0048] Preferably, the monomer liquid crystal compound of the general structure III is selected from the following structures:

[0049]

[0050] The value range of m in the above structural formula is a natural number of 1-10, and the value range of n is a natural number of 1-10.

[0051] The mass percentage of the monomer liquid crystal compound in the liquid crystal composition of the present application is ≥80% and ≤99.9%. The mass percentage of the liquid crystal compound represented by the structural general formula II is ≥80% and ≤99.9%, and the mass percentage of the liquid crystal compound represented by the structural general formula III is 0%-20%.

[0052] The liquid crystal composition of the present application can further comprise one or more chiral compounds.

[0053] Further, the preferred chiral compound has the following structural formula:

[0054]

[0055] Further, the added amount of the chiral compound in the liquid crystal composition of the present application accounts for 0.01-5% of the mass of the remaining components.

[0056] Further, the liquid crystal composition of the present application comprises one or more thermal stabilizers or light stabilizers.

[0057] The thermal stabilizer is preferably a hindered phenol stabilizer.

[0058] The further preferred thermal stabilizer has the following structural formula:

[0059]

[0060] R0 is an alkyl or alkoxy group with 1-15 carbon atoms.

[0061] The light stabilizer is preferably a UV absorbing light stabilizer or a hindered amine light stabilizer.

[0062] The further preferred UV absorbing light stabilizer has the following structural formula:

[0063]

[0064] The further preferred hindered amine light stabilizer has the following structural formula:

[0065]

[0066] Further, the added amount of the thermal stabilizer or light stabilizer in the liquid crystal composition of the present application accounts for 0.005-1% of the mass of the remaining components.

[0067] The application relates to a liquid crystal composition for a dimming glass, which comprises a dichroic dye represented by a general structural formula I and a liquid crystal composition. Further, the dimming glass can realize the regulation of light transmittance by an external voltage. By reasonably selecting the initial orientation of the liquid crystal molecules and the dielectric anisotropy, a "common white" dimming mode (i.e. the light transmittance is the largest without the external voltage) or a "common black" dimming mode (i.e. the light transmittance is the smallest without the external voltage) can be realized. Corresponding to the common white dimming mode, the initial orientation of the liquid crystal molecules is perpendicular to the substrate, and the liquid crystal composition with the negative dielectric anisotropy is adopted. Corresponding to the common black dimming mode, the initial orientation of the liquid crystal molecules is parallel to the substrate, and the liquid crystal composition with the positive dielectric anisotropy is adopted.

[0068] The dimming glass cell comprises a functional layer structure arranged in sequence, and the functional layers are combined by the known preparation process in the specific scheme.

[0069] (1) a substrate layer, preferably glass or polymer;

[0070] (2) a transparent conductive layer, preferably indium tin oxide (ITO);

[0071] (3) an orientation layer, preferably a polyimide orientation material (PI);

[0072] (4) a liquid crystal layer, which comprises one or more dichroic dyes represented by the general structural formula I and liquid crystal compounds represented by the general structural formula II or / and III;

[0073] (5) an orientation layer, preferably a polyimide orientation material (PI);

[0074] (6) a transparent conductive layer, preferably indium tin oxide (ITO);

[0075] (7) a substrate layer, preferably glass or polymer.

[0076] The dimming glass device can realize the dimming function under a lower voltage, and the preferred driving voltage is < 24v, and more preferably < 12v.

[0077] In order to achieve good dimming effect, especially to obtain higher contrast, the dimming glass device can be manufactured by any one of the following three ways:

[0078] (1) a single dimming glass cell, referred to as a single cell;

[0079] (2) a single dimming glass cell, and a polaroid is attached;

[0080] (3) two dimming glass cells are stacked, wherein the liquid crystal optical axis directions are perpendicular to each other, and the structure is referred to as a double cell.

[0081] The liquid crystal composition of the present application is prepared in a conventional manner. In an inert gas environment, such as nitrogen or argon, each liquid crystal compound is heated to dissolve uniformly. Stirring, centrifugation, ultrasonic and other methods can be used to accelerate the dissolution and homogenization process. Optionally, the heating temperature is generally in the range of 40-120°C. Further, the dichroic dye is added to the liquid crystal mixture, and after being dissolved uniformly at 40-120°C, the mixture is filtered. BRIEF DESCRIPTION OF DRAWINGS

[0082] Figure 1 The transmittance curve result graph of the dye of Example 1 and Comparative Example 1.

[0083] Figure 2 The transmittance curve result graph of the dye of Example 6 and Comparative Example 2. DETAILED DESCRIPTION

[0084] It should be noted that the detailed test methods of the physical properties and photoelectric properties involved in the present application are as follows:

[0085] (1) Liquid crystal phase transition temperature:

[0086] Differential scanning calorimetry (DSC) is used: nitrogen atmosphere, set the heating (cooling) rate to 5°C / min.

[0087] Polarizing hot stage method: the liquid crystal sample is placed in a crossed polarizing microscope hot stage, and the heating rate is set to 2°C / min. The texture image of the liquid crystal phase transition is observed in the polarizing microscope to determine the liquid crystal phase state.

[0088] (2) Birefringence (Δn): the liquid crystal monomer is added to the basic formula HOST according to a mass ratio of 15:85%, and heated and mixed uniformly. Abbe refractometer is used to measure the refractive index of ordinary light (n o ) and extraordinary light (n e ) respectively under constant temperature conditions of 25°C, and the birefringence is extrapolated.

[0089] (3) Dielectric constant (Δε, 1 kHz): the liquid crystal monomer is added to the basic formula HOST according to a mass ratio of 15:85%, and heated and mixed uniformly. LCR meter is used to test under constant temperature conditions of 25°C. Δε = ε ∥ - ε ⊥ , i.e. the difference between the dielectric constant in the long axis direction of the molecule (ε ∥ ) and the dielectric constant in the short axis direction of the molecule (ε ⊥ ), and the dielectric anisotropy value Δε is extrapolated.

[0090] (4) Rotational viscosity (γ1): under constant temperature conditions of 25°C, the transient current value Ip of the liquid crystal molecule deflection with the electric field movement is tested by applying voltage to the liquid crystal test box, and the rotational viscosity γ1 is calculated and extrapolated.

[0091] (5) Test of solubility of dichroic dye: add the dichroic dye into the parent liquid crystal according to certain mass ratio, store at room temperature to observe the solubility or crystallization, and determine the solubility.

[0092] (6) Test of dichroic ratio and order parameter of dichroic dye: fill the liquid crystal composition containing the dichroic dye into a test box with anti-parallel orientation, and perform absorbance (A) test at the wavelength of the absorption peak of the dye. Obtain A ∥ and A ⊥ ; wherein the dichroic ratio D = A ∥ / A ⊥ ;

[0093] wherein the order parameter S = (D-1) / (D+2).

[0094] (7) Test of ultraviolet light stability of dichroic dye: fill the liquid crystal composition containing the dichroic dye into a test box with anti-parallel orientation, and perform irradiation by using an ultraviolet lamp with a center wavelength of 365 nm, the total cumulative irradiation energy is 14400 J, and the color difference before and after irradiation is tested by using a haze colorimeter, and the absorption spectrum before and after irradiation is tested. The smaller the color difference and the absorption spectrum, the better the ultraviolet light stability.

[0095] Code and description:

[0096] Table 1 Physical parameters

[0097] Code Explanation Unit e ⊥ ]] Dielectric constant perpendicular to the director e ∥ ]] Dielectric constant parallel to the director Δε Dielectric anisotropy S Order parameter Δn Birefringence [gamma]1 Rotational viscosity mPa-s Tni Clearing point ℃

[0098] Liquid crystal phase transition temperature: C represents melting point, S represents smectic phase, N represents nematic phase, and I represents liquid state.

[0099] Table 2 Abbreviation of monomer liquid crystal structure

[0100]

[0101] Table 3 Examples of monomer liquid crystal abbreviation

[0102]

[0103]

[0104] The following gives specific embodiments of the present application, and it should be noted that the present application is not limited to the following specific embodiments, and any equivalent transformation made on the basis of the technical scheme of the present application falls within the protection scope of the present application.

[0105] Example 1:

[0106] The embodiment provides a dichroic dye compound, and a structural formula is as follows:

[0107]

[0108] A synthesis route is as follows:

[0109]

[0110] A specific synthesis method comprises the following steps:

[0111] (1) Synthesis of 1-ethyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline

[0112] Under nitrogen protection, 2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline (17.5 g, 0.1 mol), potassium carbonate (27.6 g, 0.2 mol), iodoethane (31.2 g, 0.4 mol) and DMF (150 mL) are sequentially added into a 500 mL three-neck flask provided with mechanical stirring and a thermometer, the system is heated to 70 DEG C and stirred for 8 h, after the raw material is substantially completely reacted, the reaction is stopped, 150 mL of toluene is added into the system, and then the organic phase is dried over anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain a crude product, and the crude product is purified by column chromatography to obtain 14.1 g of liquid 1-ethyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, with a HPLC purity of 99% and a yield of 69%.

[0113] (2) Synthesis of 6-bromo-1-ethyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline

[0114] Under nitrogen protection, 1-ethyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline (20.3 g, 0.1 mol) and DMF (150 mL) are sequentially added into a 500 mL three-neck flask provided with mechanical stirring and a thermometer, NBS (19.6 g, 0.11 mol) is added in batches under stirring, after the addition is completed, the system is stirred at room temperature overnight, after the raw material is substantially completely reacted, the reaction is stopped, 150 mL of toluene is added into the system, and then the organic phase is dried over anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain a crude product, and the crude product is purified by column chromatography to obtain 19.6 g of solid 6-bromo-1-ethyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, with a HPLC purity of 98% and a yield of 70%.

[0115] (3) Synthesis of 1-ethyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline-6-yl boronic acid

[0116] Into a 500 mL three-necked flask equipped with a mechanical stirrer and a thermometer, 6-bromo-l-ethyl-2,2,4-trimethyl-l,2,3,4-tetrahydroquinoline (28.1 g, 0.1 mol) and THF (120 mL) were added successively under nitrogen. The system was cooled to -80 °C, and then 2.5 M n-butyllithium (48 mL, 0.11 mol) was added dropwise. The addition was completed in about 30 min. The system was stirred at -80 °C for 1 h, and then trimethyl borate (12.48 g, 0.11 mol) was added dropwise. The addition was completed in about 30 min. The system was stirred at -80 °C for 1 h, and then warmed to room temperature. The system was acidified with dilute hydrochloric acid. The mixture was stirred for 30 min, and then separated. The aqueous phase was extracted with n-heptane three times. The combined organic phase was washed with water three times until neutral. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to give a crude product. The crude product was recrystallized from n-heptane to give 16.5 g of solid l-ethyl-2,2,4-trimethyl-l,2,3,4-tetrahydroquinolin-6-yl boronic acid with a HPLC purity of 98% and a yield of 67%.

[0117] (4) Synthesis of 4,7-bis(5-(l-ethyl-2,2,4-trimethyl-l,2,3,4-tetrahydroquinolin-6-yl)thiophen-2-yl)benzo[c][l,2,5]thiadiazole

[0118] Into a 250 mL three-necked flask equipped with a mechanical stirrer and a thermometer, (l-ethyl-2,2,4-trimethyl-l,2,3,4-tetrahydroquinolin-6-yl)boronic acid (7.42 g, 0.03 mol), 4,7-bis(5-bromothiophen-2-yl)benzo[c][l,2,5]thiadiazole (4.56 g, 0.01 mol), potassium carbonate (5.52 g, 0.04 mol), dichlorobis(triphenylphosphine)palladium (0.35 g, 0.5 mmol), toluene (20 mL), ethanol (20 mL), and water (20 mL) were added successively under nitrogen. The system was warmed to reflux and stirred for 8 h. The reaction was stopped, and 50 mL of toluene was added to the system. The system was washed with water three times. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to give a crude product. The crude product was purified by column chromatography, and recrystallized from toluene to give 5.4 g of solid with a HPLC purity of 99.5% and a yield of 77%.

[0119] The structure of the product was identified as follows:

[0120] 1H NMR (800 MHz, CDC13) δ (ppm): 8.10 (s, 2H), 7.82 (s, 2H), 7.49 (s, 2H), 7.44 (d, J = 8.0 Hz, 2H), 7.23 (s, 2H), 6.60 (s, 2H), 3.49 (s, 2H), 3.26 (s, 2H), 2.96 (s, 2H), 1.78-1.76 (m, 2H), 1.63-1.60 (m, 2H), 1.42 (d, J = 6.4 Hz, 6H), 1.36 (s, 6H), 1.24-1.22 (m, 12H).

[0121] 13 C NMR (200 MHz, CDC13) δ (ppm): 152.8, 147.3, 144.8, 136.4, 128.8, 127.9, 125.0, 123.9, 121.6, 121.3, 111.4, 54.7, 46.9, 39.2, 29.7, 27.4, 25.5, 20.2, 15.1.

[0122] Example 2:

[0123] This example provides a dichroic dye compound, the structural formula of which is as shown below:

[0124]

[0125] The following intermediate is used to replace the intermediate in Example 1

[0126] Other operations use the same synthesis method as Example 1 to obtain the target product.

[0127] The structure identification data are as follows:

[0128] 1 H NMR (800 MHz, CDC13) δ (ppm): 8.79 (s, 1H), 8.61 (d, J = 3.2 Hz, 1H), 8.05 (d, J = 3.2 Hz, 1H), 7.54 (s, 1H), 7.49-7.47 (m, 2H), 7.43 (d, J = 8.8 Hz, 1H), 7.30 (d, J = 3.2 Hz, 1H), 7.23 (s, 1H), 3.51-3.48 (m, 2H), 3.28-3.25 (m, 2H), 2.95-2.94 (m, 2H), 1.78-1.76 (m, 2H), 1.63-1.59 (m, 2H), 1.42 (d, J = 6.4 Hz, 6H), 1.36 (s, 6H), 1.23-1.22 (m, 12H). ​

[0129] 13 C NMR (200 MHz, CDC13) δ (ppm): 155.0, 151.1, 148.4, 147.7, 145.7, 145.4, 145.0, 140.4, 138.4, 133.6, 133.4, 129.0, 128.0, 127.9, 125.10, 125.07, 124.1, 123.9, 122.4, 121.6, 121.1, 121.0, 120.1, 111.4, 54.8, 54.7, 46.9, 46.8, 39.2, 29.7, 27.37, 27.35, 25.6, 25.5, 20.2, 20.1, 15.06, 15.02.

[0130] Example 3:

[0131] The present embodiment provides a dichroic dye compound, the structural formula of which is shown as follows:

[0132]

[0133] The synthetic route thereof is shown as follows:

[0134]

[0135] The specific synthesis method comprises the following steps:

[0136] (1) Synthesis of 4-bromo-7-(3-fluoro-4'-pentyl-[1,1'-biphenyl]-4-yl)benzo[c][1,2,5]thiadiazole

[0137] Under nitrogen protection, a 500 mL three-necked flask equipped with mechanical stirring and thermometer was added with 4,7-dibromobenzo[c][1,2,5]thiadiazole (29.2 g, 0.1 mol), (3-fluoro-4'-pentyl-[1,1'-biphenyl]-4-yl)boronic acid (31.5 g, 0.11 mol), potassium carbonate (27.6 g, 0.2 mol), dichlorobis(triphenylphosphine)palladium (3.5 g, 5 mmol), toluene (80 mL), ethanol (80 mL) and water (80 mL) in sequence, the system was heated to reflux and stirred for 8 h, and then the reaction was stopped. After 150 mL of toluene was added to the system, it was washed with water three times, and the organic phase was dried over anhydrous magnesium sulfate, filtered and rotary evaporated to obtain a crude product. The crude product was purified by column chromatography, and 25.4 g of solid 4-bromo-7-(3-fluoro-4'-pentyl-[1,1'-biphenyl]-4-yl)benzo[c][1,2,5]thiadiazole was obtained by recrystallization from toluene, with an HPLC purity of 97% and a yield of 56%.

[0138] (2) Synthesis of 4-(3-fluoro-4'-pentyl-[1,1'-biphenyl]-4-yl)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole

[0139] Under nitrogen protection, 4-(3-fluoro-4'-pentyl-[1,1'-biphenyl]-4-yl)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (9.16 g, 0.02 mol) and DMF (120 mL) were added into a 250 mL three-necked flask equipped with mechanical stirrer and thermometer successively. Then, NBS (3.92 g, 0.022 mol) was added in batches under stirring. After the addition, the reaction was stirred at room temperature overnight. After the starting material was consumed completely as monitored by TLC, the reaction was stopped. Then, 80 mL of toluene was added into the system, which was washed with water for three times. The organic phase was dried over anhydrous magnesium sulfate, filtered and concentrated to give a crude product. The crude product was purified by column chromatography to give 8.0 g of 4-(5-bromothiophen-2-yl)-7-(3-fluoro-4'-pentyl-[1,1'-biphenyl]-4-yl)benzo[c][1,2,5]thiadiazole as a solid with a purity of 98% by HPLC, and the yield was 75%.

[0140] (3) Synthesis of 4-(5-bromothiophen-2-yl)-7-(3-fluoro-4'-pentyl-[1,1'-biphenyl]-4-yl)benzo[c][1,2,5]thiadiazole

[0141] Under nitrogen protection, 4-(3-fluoro-4'-pentyl-[1,1'-biphenyl]-4-yl)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (9.16 g, 0.02 mol) and DMF (120 mL) were added into a 250 mL three-necked flask equipped with mechanical stirrer and thermometer successively. Then, NBS (3.92 g, 0.022 mol) was added in batches under stirring. After the addition, the reaction was stirred at room temperature overnight. After the starting material was consumed completely as monitored by TLC, the reaction was stopped. Then, 80 mL of toluene was added into the system, which was washed with water for three times. The organic phase was dried over anhydrous magnesium sulfate, filtered and concentrated to give a crude product. The crude product was purified by column chromatography to give 8.0 g of 4-(5-bromothiophen-2-yl)-7-(3-fluoro-4'-pentyl-[1,1'-biphenyl]-4-yl)benzo[c][1,2,5]thiadiazole as a solid with a purity of 98% by HPLC, and the yield was 75%.

[0142] (4) Synthesis of 4-(5-(1-ethyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinolin-6-yl)thiophen-2-yl)-7-(3-fluoro-4'-pentyl-[1,1'-biphenyl]-4-yl)benzo[c][1,2,5]thiadiazole

[0143] Into a 250 mL three-necked flask, equipped with a mechanical stirrer and a thermometer, was placed (1-ethyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinolin-6-yl)boronic acid (3.71 g, 0.015 mol), 4-(5-bromothiophen-2-yl)-7-(3-fluoro-4'-pentyl-[1,1'-biphenyl]-4-yl)benzo[c][1,2,5]thiadiazole (5.36 g, 0.01 mol), potassium carbonate (2.76 g, 0.02 mol), dichlorobis(triphenylphosphine)palladium (0.18 g, 0.25 mmol), toluene (20 mL), ethanol (20 mL) and water (20 mL) under nitrogen. The reaction mixture was heated to reflux for 8 h. The reaction mixture was cooled to room temperature and then quenched with 50 mL of toluene. The organic phase was washed with water three times. The organic phase was dried over anhydrous magnesium sulfate, filtered and concentrated to give a crude product. The crude product was purified by column chromatography and recrystallized from toluene to give 3.6 g of a solid with a purity of 99.5% by HPLC, in a yield of 55%.

[0144] The structure identification data are as follows:

[0145] 1 H NMR (800 MHz, CDC13) δ (ppm): 8.17 (d, J = 4.0 Hz, 1H), 7.92 (d, J = 7.2 Hz, 1H), 7.83 (t, J = 7.2 Hz, 1H), 7.76 (d, J = 7.2 Hz, 1H), 7.58 (d, J = 8.0 Hz, 2H), 7.55-7.54 (m, 1H), 7.50 (s, 1H), 7.49-7.45 (m, 2H), 7.30 (d, J = 7.2 Hz, 2H), 7.25 (s, 1H), 6.61 (d, J = 8.8 Hz, 1H), 3.51-3.48 (m, 1H), 3.28-3.25 (m, 1H), 2.96 (s, 1H), 2.68 (t, J = 8.0 Hz, 2H), 1.79-1.76 (m, 1H), 1.70-1.66 (m, 2H), 1.63-1.60 (m, 1H), 1.43 (d, J = 6.4 Hz, 3H), 1.39-1.37 (m, 4H), 1.36 (s, 3H), 1.25-1.23 (m, 6H), 0.93 (t, J = 7.2 Hz, 3H).

[0146] 13C NMR (200 MHz, CDC13) δ (ppm): 161.0, 159.8, 154.4, 152.5, 147.8, 144.9, 143.4 (d, J = 8.0 Hz), 143.2, 137.0, 136.0, 132.4 (d, J = 4.0 Hz), 130.5, 129.5, 129.2, 127.8 (d, J = 48.0 Hz), 127.0, 126.2, 125.0, 124.5, 124.0, 123.7 (d, J = 16.0 Hz), 122.7 (d, J = 2.0 Hz), 121.7, 121.2, 114.5 (d, J = 22.0 Hz), 111.4, 54.7, 46.9, 39.2, 35.8, 31.7, 31.3, 29.7, 27.4, 25.5, 22.7, 20.2, 15.1, 14.2.

[0147] Example 4:

[0148] This example provides a dichroic dye compound, the structural formula of which is shown below:

[0149]

[0150] The same synthetic method was used to obtain the target product by replacing 3-fluoro-4'-n-pentyl biphenyl boronic acid in Example 3 with 4-n-pentyl phenyl boronic acid.

[0151] The structure identification data are as follows:

[0152] 1 H NMR (800 MHz, CDC13) δ (ppm): 8.13 (d, J = 3.2 Hz, 1H), 7.90-7.88 (m, 3H), 7.70 (d, J = 7.2 Hz, 1H), 7.49 (s, 1H), 7.45-7.44 (m, 1H), 7.36 (d, J = 8.8 Hz, 2H), 7.25 (s, 1H), 6.61 (d, J = 5.6 Hz, 1H), 3.49 (s, 1H), 3.26 (s, 1H), 2.96 (s, 1H), 2.70 (t, J = 8.0 Hz, 2H), 1.78-1.76 (m, 1H), 1.72-1.68 (m, 2H), 1.63-1.60 (m, 1H), 1.42 (d, J = 6.4 Hz, 3H), 1.40-1.38 (m, 4H), 1.36 (s, 3H), 1.25-1.23 (m, 6H), 0.93 (t, J = 7.2 Hz, 3H).

[0153] 13C NMR (200 MHz, CDC13) δ (ppm): 154.3, 152.9, 147.4, 144.9, 143.3, 136.2, 134.9, 132.1, 129.1, 129.0, 128.8, 128.0, 127.9, 126.7, 125.0, 123.9, 121.6, 121.3, 111.4, 54.7, 46.9, 39.2, 35.9, 31.7, 31.3, 29.7, 27.4, 25.4, 22.7, 20.2, 15.1, 14.2.

[0154] Example 5:

[0155] This example provides a dichroic dye compound, the structural formula of which is as shown below:

[0156]

[0157] The target product was obtained by replacing 2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline in Example 1 with 1,2,3,4-tetrahydroquinoline, and using the same synthesis method as in Example 1.

[0158] The structure identification data are as follows:

[0159] 1 H NMR (800 MHz, CDC13) δ (ppm): 8.07-8.06 (m, 2H), 7.80-7.79 (m, 2H), 7.41 (d, J = 8.8 Hz, 2H), 7.31 (s, 2H), 7.21 (d, J = 2.4 Hz, 2H), 6.61 (d, J = 8.0 Hz, 2H), 3.39 (q, J = 7.2 Hz, 4H), 3.31 (t, J = 5.6 Hz, 4H), 2.81 (t, J = 6.4 Hz, 4H), 2.01-1.98 (m, 4H), 1.17 (t, J = 7.2 Hz, 6H).

[0160] 13 C NMR (200 MHz, CDC13) δ (ppm): 152.8, 147.0, 145.1, 136.3, 128.7, 126.9, 125.6, 125.04, 124.96, 122.7, 121.63, 121.55, 110.6, 48.6, 45.5, 28.3, 22.3, 11.1.

[0161] Example 6:

[0162] This example provides a dichroic dye compound, the structural formula of which is as shown below:

[0163]

[0164] The synthetic route is shown as follows:

[0165]

[0166] The specific synthesis method is as follows:

[0167] (1) Synthesis of 2-(3-hydroxy-3-methylbutyl)phenol

[0168] A 1 L three-necked flask equipped with mechanical stirring and thermometer was placed in a water bath under nitrogen protection, and dihydrocoumarin (32.6 g, 0.22 mol) and toluene (200 mL) were sequentially added to the flask, and methyl magnesium bromide (500 mL, 1 mol / L) was added dropwise under stirring, and after the dropwise addition was completed, the reaction was continued to stir for 2 h, and thin layer plate monitoring showed that no raw material remained, and the reaction was stopped. A dilute sulfuric acid solution was slowly added to the system, and a large amount of solid was precipitated. Toluene and water were added to the system for liquid-liquid separation, and the organic phase was washed with water three times and then rotary evaporated to obtain 36.2 g of white solid 2-(3-hydroxy-3-methylbutyl)phenol with an HPLC purity of 99% and a yield of 91%.

[0169] (2) Synthesis of 2,2-dimethylchromane

[0170] Under nitrogen protection, a 1 L three-necked flask equipped with mechanical stirring and thermometer was added with 2-(3-hydroxy-3-methylbutyl)phenol (44.3 g, 0.22 mol), 18% dilute sulfuric acid (330 mL) and toluene (90 mL), and heated to reflux and stirred for 4 h. Thin layer plate monitoring showed that no raw material remained, and the reaction was stopped. The reaction solution was washed with toluene until neutral, and the organic phase was rotary evaporated to obtain 30.2 g of red-brown oil 2,2-dimethylchromane with an HPLC purity of 98.2% and a yield of 85%.

[0171] (3) Synthesis of 6-bromo-2,2-dimethylchromane

[0172] A 1 L three-necked flask equipped with mechanical stirring and thermometer was added with 2,2-dimethylchromane (15 g, 80.4 mmol), glacial acetic acid (4.83 g, 80.4 mmol) and dichloromethane (50 mL). NBS (14.15 g, 79.6 mmol) was added in portions, and stirred at room temperature overnight. Thin layer plate monitoring showed that no raw material remained, and the reaction was stopped. Toluene was added to the system and washed with water three times, and the organic phases were combined, dried with anhydrous magnesium sulfate, filtered and rotary evaporated to obtain 18.3 g of black oil 6-bromo-2,2-dimethylchromane with an HPLC purity of 99% and a yield of 94%.

[0173] (4) Synthesis of (2,2-dimethylchroman-6-yl)boronic acid

[0174] Into a 500 mL three-necked flask equipped with a mechanical stirrer and a thermometer, 6-bromo-2,2-dimethylchromane (24.0 g, 0.1 mol) and THF (180 mL) were added successively under nitrogen. The system was cooled to -80 °C, and then 2.5 M n-butyllithium (48 mL, 0.11 mol) was added dropwise. The addition was completed in about 30 min. The system was kept stirring at -80 °C for 1 h, and then trimethyl borate (12.48 g, 0.11 mol) was added dropwise. The addition was completed in about 30 min. The system was kept stirring at -80 °C for 1 h, and then warmed to room temperature. The system was acidified with dilute hydrochloric acid, and then stirred for 30 min. The organic phase was separated, and then extracted with n-heptane (3 x 50 mL). The combined organic phase was washed with water (3 x 50 mL) until neutral, dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to give a crude product. The crude product was recrystallized from n-heptane to give (2,2-dimethylchroman-6-yl)boronic acid (15.5 g, 97% by HPLC) as a white solid in 75% yield.

[0175] (5) Synthesis of 4,7-bis(5-(2,2-dimethylchroman-6-yl)thiophen-2-yl)benzo[c][1,2,5]thiadiazole

[0176] Into a 250 mL three-necked flask equipped with a mechanical stirrer and a thermometer, (2,2-dimethylchroman-6-yl)boronic acid (6.18 g, 0.03 mol), 4,7-bis(5-bromothiophen-2-yl)benzo[c][1,2,5]thiadiazole (4.56 g, 0.01 mol), potassium carbonate (5.52 g, 0.04 mol), dichlorobis(triphenylphosphine)palladium (0.36 g, 0.5 mmol), toluene (20 mL), ethanol (20 mL), and water (20 mL) were added successively under nitrogen. The system was heated to reflux and stirred for 8 h. The system was acidified with dilute hydrochloric acid, and then stirred for 30 min. The organic phase was separated, and then extracted with n-heptane (3 x 50 mL). The combined organic phase was washed with water (3 x 50 mL) until neutral, dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to give a crude product. The crude product was purified by column chromatography, and then recrystallized from toluene to give 4,7-bis(5-(2,2-dimethylchroman-6-yl)thiophen-2-yl)benzo[c][1,2,5]thiadiazole (3.8 g, 99.5% by HPLC) as a solid in 61% yield.

[0177] The structure identification data are as follows:

[0178] 1 H NMR (800 MHz, CDC13) δ (ppm): 8.08 (d, J = 4.0 Hz, 2H), 7.86 (s, 2H), 7.45 (d, J = 8.0 Hz, 2H), 7.43 (s, 2H), 7.28 (d, J = 3.2 Hz, 2H), 6.83 (d, J = 8.0 Hz, 2H), 2.85 (t, J = 7.2 Hz, 4H), 1.85 (t, J = 6.4 Hz, 4H), 1.37 (s, 12H).

[0179] 13 C NMR (200 MHz, CDC13) δ (ppm): 154.4, 152.8, 146.2, 137.5, 128.7, 127.2, 126.1, 125.8, 125.27, 125.25, 122.9, 121.5, 118.0, 74.8, 32.9, 27.1, 22.7.

[0180] Example 7:

[0181] This example provides a dichroic dye compound, the structural formula of which is as shown below:

[0182]

[0183] The same synthetic method was used to obtain the target product by replacing 1-ethyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline-6-yl)boronic acid in Example 3 with (2,2-dimethylchroman-6-yl)boronic acid.

[0184] The structure identification data are as follows:

[0185] 1 H NMR (800 MHz, CDC13) δ (ppm): 8.12 (d, J = 4.0 Hz, 1H), 7.94 (d, J = 7.2 Hz, 1H), 7.83 (t, J = 8.0 Hz, 1H), 7.77 (d, J = 7.2 Hz 1H), 7.58 (d, J = 8.0 Hz, 2H), 7.54-7.53 (m, 1H), 7.49-7.46 (m, 2H), 7.44 (s, 1H), 7.31-7.29 (m, 2H), 6.84 (d, J = 8.0 Hz, 1H), 2.85 (t, J = 6.4 Hz, 2H), 2.67 (t, J = 8.0 Hz, 2H), 1.86 (t, J = 6.4 Hz, 2H), 1.69-1.66 (m, 2H), 1.38-1.36 (m, 10H), 0.93 (t, J = 6.4 Hz, 3H).

[0186] 13C NMR (200 MHz, CDC13) δ (ppm): 161.0, 159.8, 154.4 (d, J = 8.0 Hz), 152.5, 146.5, 143.6 (d, J = 8.0 Hz), 143.2, 137.3, 137.0, 132.3 (d, J = 4.0 Hz), 130.4 (d, J = 4.0 Hz), 129.18, 129.16, 127.4, 127.2, 127.1, 126.7, 126.1, 125.3, 124.8, 123.6 (d, J = 14.0 Hz), 122.9, 122.7 (d, J = 2.0 Hz), 121.5, 118.0, 114.6 (d, J = 22.0 Hz), 74.8, 35.8, 32.9, 31.7, 31.3, 27.0, 22.71, 22.65, 14.2.

[0187] Example 8:

[0188] This example provides a dichroic dye compound, the structural formula of which is as shown below:

[0189]

[0190] The same synthetic method was used to obtain the target product by replacing (3-fluoro-4'-pentyl-[1,1'-biphenyl]-4-yl)boronic acid in Example 3 with 5-(4-n-pentylphenyl)thiophene-2-boronic acid and replacing 1-ethyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinolin-6-yl)boronic acid in Example 3 with (2,2-dimethylchroman-6-yl)boronic acid.

[0191] The structure identification data are as follows:

[0192] 1 H NMR (800 MHz, CDC13) δ (ppm): 8.09 (d, J = 4.0 Hz, 1H), 8.08 (d, J = 3.2 Hz, 1H), 7.86-7.84 (m, 2H), 7.62 (d, J = 8.0 Hz 2H), 7.46-7.44 (m, 1H), 7.42 (s, 1H), 7.37 (d, J = 4.0 Hz 1H), 7.27 (d, J = 4.0 Hz, 1H), 7.23 (d, J = 8.0 Hz, 2H), 6.83 (d, J = 8.8 Hz, 1H), 2.85 (t, J = 6.4 Hz, 2H), 2.64 (t, J = 8.0 Hz, 2H), 1.85 (t, J = 6.4 Hz, 2H), 1.67-1.63 (m, 2H), 1.37-1.34 (m, 10H), 0.91 (t, J = 6.4 Hz, 3H).

[0193] 13 C NMR (200 MHz, CDC13) δ (ppm): 154.3, 152.63, 152.61, 146.1, 145.7, 142.9, 138.2, 137.3, 131.6, 129.0, 128.6, 128.5, 127.0, 126.0, 125.9, 125.8, 125.5, 125.3, 125.1, 125.0, 126.6, 122.8, 121.4, 117.8, 74.7, 35.7, 32.8, 31.5, 31.1, 26.9, 22.6, 22.5, 14.0.

[0194] Example 9:

[0195] This example provides a dichroic dye compound, the structural formula of which is shown as follows:

[0196]

[0197] The synthetic route thereof is shown as follows:

[0198]

[0199] The specific synthesis method is as follows:

[0200] The synthesis of (2,2-dimethylchroman-6-yl)boronic acid is the same as that of Example 6, and the target product is obtained.

[0201] (1) Synthesis of 6-(4-bromophenyl)-2,2-dimethylchroman

[0202] Under nitrogen protection, a 500 mL three-necked flask equipped with mechanical stirring and a thermometer was added (2,2-dimethylchroman-6-yl)boronic acid (10.3 g, 0.05 mol), 4-bromiodobenzene (14.1 g, 0.05 mol), potassium carbonate (13.8 g, 0.1 mol), dichlorobis(triphenylphosphine)palladium (0.18 g, 0.25 mmol), toluene (40 mL), ethanol (40 mL) and water (40 mL) in sequence, the system was heated to reflux and stirred for 8 h, then the reaction was stopped. After 50 mL of toluene was added to the system, it was washed with water three times, and the organic phase was dried over anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain a crude product. The crude product was purified by column chromatography, and 11.2 g of solid was obtained by recrystallization with n-heptane, with a GC purity of 95% and a yield of 71%.

[0203] (2) Synthesis of 4-(2,2-dimethylchroman-6-yl)phenylboronic acid

[0204] Into a 500 mL three-necked flask equipped with a mechanical stirrer and a thermometer, 6-(4-bromophenyl)-2,2-dimethylchromane (9.48 g, 0.03 mol) and THF (120 mL) were added successively under nitrogen. The mixture was cooled to -80 °C, and then 2.5 M n-butyllithium (14.4 mL, 0.036 mol) was added dropwise. The mixture was stirred at -80 °C for 1 h after the addition was completed. Trimethyl borate (3.74 g, 0.036 mol) was added dropwise. The mixture was stirred at -80 °C for 1 h after the addition was completed. The mixture was allowed to warm to room temperature. The mixture was acidified with dilute hydrochloric acid. The mixture was stirred for 30 min. The organic phase was separated. The aqueous phase was extracted with n-heptane (3 times). The combined organic phase was washed with water (3 times) until neutral. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to give a crude product. The crude product was washed with n-heptane to give 6.34 g of a white solid. The purity was 97% by HPLC. The yield was 75%.

[0205] (3) Synthesis of 4,7-bis(4-(2,2-dimethylchroman-6-yl)phenyl)benzo[c][1,2,5]thiadiazole

[0206] Into a 250 mL three-necked flask equipped with a mechanical stirrer and a thermometer, 4-(2,2-dimethylchroman-6-yl)phenylboronic acid (8.46 g, 0.03 mol), 4,7-dibromobenzo[c][1,2,5]thiadiazole (2.92 g, 0.01 mol), potassium carbonate (5.52 g, 0.04 mol), dichlorobis(triphenylphosphine)palladium (0.36 g, 0.5 mmol), toluene (20 mL), ethanol (20 mL), and water (20 mL) were added successively under nitrogen. The mixture was stirred at reflux for 8 h. The mixture was cooled to room temperature. The mixture was washed with water (3 times). The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to give a crude product. The crude product was purified by column chromatography. The product was recrystallized from toluene to give 4.4 g of a solid. The purity was 99.6% by HPLC. The yield was 72%.

[0207] The structure identification data are as follows:

[0208] 1 H NMR (800 MHz, CDC13) δ (ppm): 8.04 (d, J = 7.2 Hz, 4H), 7.84 (s, 2H), 7.74 (d, J = 8.0 Hz, 4H), 7.44 (d, J = 8.0 Hz, 2H), 7.41 (s, 2H), 6.90 (d, J = 8.0 Hz, 2H), 2.88 (t, J = 6.4 Hz, 4H), 1.87 (t, J = 6.4 Hz, 4H), 1.39 (s, 12H).

[0209] 13C NMR (200 MHz, CDCI3) δ (ppm): 154.3, 154.1, 141.2, 135.6, 133.0, 132.3, 129.7, 128.3, 128.0, 127.0, 126.2, 121.3, 117.9, 74.7, 33.0, 27.1, 22.8.

[0210] Example 10:

[0211] This example provides a dichroic dye compound, the structural formula of which is as shown below:

[0212]

[0213] The target product was obtained by the same synthetic method by replacing (3-fluoro-4'-pentyl-[1,1 '-biphenyl]-4-yl)boronic acid in Example 3 with 4-n-pentylphenylboronic acid and replacing 1 -ethyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinolin-6-yl)boronic acid in Example 3 with (2,2-dimethylchroman-6-yl)boronic acid.

[0214] The structure identification data are as follows:

[0215] 1 H NMR (800 MHz, CDCI3) δ (ppm): 8.09 (d, J = 3.2 Hz, 1 H), 7.91 (d, J = 7.2 Hz, 1 H), 7.88 (d, J = 8.8 Hz, 2H), 7.70 (d, J = 7.2 Hz, 1 H), 7.46-7.45 (m, 1 H), 7.43 (s, 1 H), 7.36 (d, J = 8.0 Hz, 2H), 7.28 (d, J = 4.0 Hz, 1 H), 6.83 (d, J = 8.8 Hz, 1 H), 2.85 (t, J = 6.4 Hz, 2H), 2.70 (t, J = 8.0 Hz, 2H), 1.85 (t, J = 6.4 Hz, 2H), 1.72-1.68 (m, 2H), 1.40-1.38 (m, 10H), 0.93 (t, J = 7.2 Hz, 3H).

[0216] 13 C NMR (200 MHz, CDCI3) δ (ppm): 154.3, 154.2, 152.9, 146.1, 143.5, 137.5, 134.8, 132.6, 129.2, 128.9, 128.7, 127.9, 127.2, 126.4, 126.1, 125.30, 125.26, 122.8, 121.5, 117.9, 74.8, 35.9, 32.9, 31.7, 31.3, 27.0, 22.73, 22.65, 14.2.

[0217] Example 11:

[0218] The present example provides a dichroic dye compound, the structural formula of which is shown as follows:

[0219]

[0220] The synthetic route thereof is shown as follows:

[0221]

[0222] The specific synthesis method is as follows:

[0223] (1) Synthesis of (5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)boronic acid

[0224] Under nitrogen protection, a 500 mL three-necked flask equipped with mechanical stirring and thermometer was added with 6-bromo-1,1,4,4-tetramethyl-1,2,3,4-tetrahydronaphthalene (7.98 g, 0.03 mol) and THF (120 mL) in sequence, the system was cooled to -80°C, then 2.5M n-butyllithium (14.4 mL, 0.036 mol) was added dropwise, the dropwise addition was completed in about 30 min, the stirring was continued for 1 h after the system was kept at -80°C, then trimethyl borate (3.74 g, 0.036 mol) was added dropwise, the dropwise addition was completed in about 30 min, the stirring was continued for 1 h after the system was kept at -80°C, and then the system was naturally warmed to room temperature. Dilute hydrochloric acid was added to the system until it was acidic, the system was stirred for 30 min, then it was separated, the water phase was extracted with n-heptane for three times, the combined organic phase was washed with water for three times until it was neutral, then it was dried over anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain a crude product, the crude product was filtered after being slurried with n-heptane to obtain 5.57 g of white solid (5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)boronic acid, the HPLC purity was 98%, and the yield was 80%.

[0225] (2) Synthesis of 4,7-bis(5-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)thiophen-2-yl)benzo[c][1,2,5]thiadiazole

[0226] Into a 250 mL three-necked flask equipped with a mechanical stirrer and a thermometer, (5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)boronic acid (6.96 g, 0.03 mol), 4,7-bis(5-bromothiophen-2-yl)benzo[c][1,2,5]thiadiazole (4.56 g, 0.01 mol), potassium carbonate (5.52 g, 0.04 mol), dichlorobis(triphenylphosphine)palladium (0.36 g, 0.5 mmol), toluene (20 mL), ethanol (20 mL) and water (20 mL) were added successively under nitrogen. The reaction mixture was heated to reflux for 8 h. The reaction mixture was cooled to room temperature and then poured into 50 mL of toluene. The mixture was washed with water three times. The organic phase was dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to give a crude product. The crude product was purified by column chromatography and recrystallized from toluene to give 3.96 g of a solid with a purity of 99.5% by HPLC, in a yield of 59%.

[0227] The structure identification data are as follows:

[0228] 1 H NMR (800 MHz, CDC13) δ (ppm): 8.13 (d, J = 6.4 Hz, 2H), 7.89 (s, 2H), 7.63 (d, J = 2.4 Hz, 2H), 7.49-7.47 (m, 2H), 7.38-7.35 (m, 4H), 1.73 (s, 8H), 1.38 (s, 12H), 1.32 (s, 12H).

[0229] 13 C NMR (200 MHz, CDC13) δ (ppm): 152.8, 146.3, 145.7, 145.2, 138.3, 131.6, 128.8, 127.4, 125.5, 124.3, 123.8, 123.5, 35.3, 35.2, 34.6, 34.4, 32.1, 31.9.

[0230] Example 12:

[0231] This example provides a dichroic dye compound, the structural formula of which is as shown below:

[0232]

[0233] The same synthetic method as in Example 6 was used to obtain the target product. The same synthetic method as in Example 6 was used to obtain the target product. The same synthetic method as in Example 6 was used to obtain the target product.

[0234] The structure identification data are as follows:

[0235] 1H NMR (500 MHz, CDCI3) δ (ppm): 7.72-7.68 (m, 6H), 6.95 (d, J = 8.5 Hz, 2H), 2.91 (t, J = 6.5 Hz, 4H), 1.88 (t, J = 6.5 Hz, 4H), 1.40 (s, 12H).

[0236] 13 C NMR (125 MHz, CDCI3) δ (ppm): 154.6, 154.4, 132.5, 130.5, 129.2, 128.4, 127.5, 121.1, 117.7, 74.8, 33.0, 27.1, 22.8.

[0237] Example 13:

[0238] The present example provides a dichroic dye compound, the structural formula of which is as shown below:

[0239]

[0240] Using the same synthetic method as in Example 6, the target product is obtained. Substituting the compound in Example 6 with The same synthetic method is used to obtain the target product.

[0241] The structure identification data are as follows:

[0242] 1 H NMR (500 MHz, CDCI3) δ (ppm): 8.70 (s, 1H), 8.45-8.43 (m, 1H), 8.38-8.37 (m, 1H), 7.75-7.73 (m, 2H), 6.98-6.96 (m, 2H), 2.96-2.90 (m, 4H), 1.90-1.87 (m, 4H), 1.40 (s, 12H).

[0243] 13 C NMR (125 MHz, CDCI3) δ (ppm): 157.0, 156.6, 155.0, 151.5, 149.8, 142.1, 131.3, 130.4, 129.5, 128.9, 128.3, 126.3, 126.1, 121.5, 121.3, 117.9, 117.7, 75.2, 74.9, 32.94, 32.93, 27.1, 22.81, 22.76.

[0244] The liquid crystal compound of the present application can be prepared by using commercially available products or based on the known methods related to the prior art. The following examples are configured by combining a plurality of liquid crystal compounds, aiming to obtain a desired liquid crystal composition for dimming glass.

[0245] Example 14:

[0246] This example provides a liquid crystal composition: the liquid crystal composition number of this example is M1, the components and mass percentage and its performance parameters are as shown in Table 4:

[0247] Table 4 Components and mass percentage and its performance parameters

[0248]

[0249] Example 15:

[0250] This example provides a liquid crystal composition: the liquid crystal composition number of this example is M2, the components and mass percentage and its performance parameters are as shown in Table 5:

[0251] Table 5 Components and mass percentage and its performance parameters

[0252]

[0253] Example 16:

[0254] This example provides a liquid crystal composition: the liquid crystal composition number of this example is M3, the components and mass percentage and its performance parameters are as shown in Table 6:

[0255] Table 6 Components and mass percentage and its performance parameters

[0256]

[0257] Example 17:

[0258] This example provides a liquid crystal composition: the liquid crystal composition number of this example is M4, the components and mass percentage and its performance parameters are as shown in Table 7:

[0259] Table 7 Components and mass percentage and its performance parameters

[0260]

[0261] Example 18:

[0262] The present embodiment provides a liquid crystal composition: the dye compounds obtained in Examples 1-13 are added to M1 shown in Example 14 according to the mass percentage of 0.5% dichroic dye and 99.5% liquid crystal compound, heated and mixed uniformly to obtain liquid crystal compositions M5-M17 containing dichroic dyes. M5-M17 are respectively filled into test boxes with a box gap of 17 μm, UV irradiation test is carried out, the test wavelength is 365 nm, the total light energy is 14400 J, the color difference ΔE before and after UV irradiation is tested, if the color difference ΔE < 1.0, it indicates that the dye has high light stability. The transmittance of the liquid crystal composition containing the dye is tested, and the maximum absorption wavelength is obtained. At the maximum absorption wavelength, the order parameter is tested and calculated.

[0263] The dye is added to M1 in different proportions, and the room temperature storage observation is carried out, and the solubility at room temperature is tested and obtained.

[0264] Table 8 Light stability, order parameter and solubility of the dye

[0265]

[0266] As can be seen from the data in Table 8, the dichroic dyes obtained in Examples 1-13 have a color difference ΔE of 0.5 or less after UV irradiation, indicating that these dyes have high light stability. At the same time, these dyes have high order parameters and large solubilities; among them, the solubility of some dyes is ≥5%, thus it can be seen that the dichroic dyes of the present application have excellent mutual solubility with liquid crystals.

[0267] Example 19:

[0268] The present embodiment provides a liquid crystal composition, the mass ratio of dye liquid crystal composition M18 is as follows:

[0269] Table 9 Mass ratio of dye liquid crystal composition M18

[0270]

[0271]

[0272] The dye liquid crystal composition M18 is suitable for parallel alignment common black mode liquid crystal dimming glass device.

[0273] Example 20:

[0274] The present embodiment provides a liquid crystal composition, the mass ratio of dye liquid crystal composition M19 is as follows:

[0275] Table 10 Mass ratio of dye liquid crystal composition M19

[0276]

[0277] Dye liquid crystal composition M19, suitable for homeotropically aligned, normally black mode liquid crystal switchable glass device.

[0278] Example 21:

[0279] This example provides a liquid crystal composition, the mass ratio of dye liquid crystal composition M20 is as follows:

[0280] Table 11 Mass ratio of dye liquid crystal composition M20

[0281]

[0282]

[0283] Dye liquid crystal composition M20, suitable for homeotropically aligned, normally white mode liquid crystal switchable glass device.

[0284] Example 22:

[0285] This example provides a liquid crystal composition, the mass ratio of dye liquid crystal composition M21 is as follows:

[0286] Table 12 Mass ratio of dye liquid crystal composition M21

[0287]

[0288] Dye liquid crystal composition M21, suitable for liquid crystal switchable glass device with twisted alignment of liquid crystal molecules, wherein the twist angle is 180-270 degrees.

[0289] Comparative Example 1:

[0290] This comparative example is a dichroic dye containing benzothiadiazole disclosed in patent CN105377995A, the molecular structure is as follows:

[0291]

[0292] The maximum absorption peak of the dye is 584 nm, which is a blue dye. It is mixed with the M1 composition described in Example 14 at a mass ratio of 0.5% and 99.5% to obtain a liquid crystal composition containing the dye.

[0293] As a comparison, the dichroic dye of Example 1 is mixed with the M1 composition described in Example 14 at a mass ratio of 0.5% and 99.5% to obtain a liquid crystal composition containing the dye.

[0294] The above dye liquid crystal compositions are respectively filled into a test cell with a box thickness of 17 μm and a homeotropic rubbing alignment, and the transmittance curve is tested, and the results are shown in the following figures: Figure 1 .

[0295] It can be seen that the dichroic dye of Example 1 has a significant red shift in the transmittance curve at the same addition amount; the maximum absorption peak red shifts about 14 nm; and Example 1 has a lower transmittance, which indicates that the dichroic dye of Example 1 has a larger extinction coefficient; and the dichroic dye of Example 1 has a wider absorption range of visible light, thereby having a greater light modulation capacity.

[0296] Comparative Example 2:

[0297] The comparative example is a benzothiadiazole dye containing a pentoxy end group, and the structural formula is as follows:

[0298]

[0299] The maximum absorption peak of the dye is 526 nm, which is a red dye.

[0300] The dye is mixed with the composition M1 described in Example 14 at a mass ratio of 0.5% to 99.5% to obtain a liquid crystal composition containing the dye.

[0301] Solubility test: The dye of Comparative Example 2 is dissolved in the composition M1 described in Example 14 at a mass ratio of 0.25%, 0.50%, and 1.0%, respectively, and stored at room temperature for 10 days to observe the dissolution.

[0302] As a comparison, the dichroic dye of Example 6 has a maximum absorption peak of 537 nm, which is a red dye.

[0303] The dichroic dye of Example 6 is mixed with the M1 composition described in Example 14 at a mass ratio of 0.5% to 99.5% to obtain a liquid crystal composition containing the dye.

[0304] Solubility test: The dye of Example 6 is dissolved in the composition of Example 1 at a mass ratio of 0.25%, 0.50%, and 1.0%, respectively, and stored at room temperature for 10 days to observe the dissolution.

[0305] Table 13 solubility test

[0306] Dye 0.25％ 0.50％ 1.0％ Comparative Example 2 No precipitation Precipitation Precipitation Example 6 No precipitation No precipitation No precipitation

[0307] It can be seen that the solubility of Example 6 is greatly increased compared to Comparative Example 2.

[0308] The above dye liquid crystal compositions are respectively filled into a test box with a box thickness of 17 μm and a reverse parallel rubbing orientation, and the transmittance curve is tested, and the results are shown in the following table 14. Figure 2 .

[0309] It can be seen that the dichroic dye of the embodiment 6 of the present application has obvious red shift of the transmittance curve under the same addition amount; the maximum absorption peak is red shifted by 11 nm; and the embodiment 6 has lower transmittance, which indicates that the dichroic dye of the embodiment 7 has greater extinction coefficient; and the dichroic dye of the embodiment 6 has wider absorption range of visible light, thereby having greater light modulation capacity.

Claims

1. A dichroic dye, characterized in that, The dichroic dye has the following general structural formula I: In Formula I: W represents an oxygen atom, a sulfur atom, or a selenium atom; X is either C-L2 or a nitrogen atom; L1 and L2 are each independently selected from hydrogen atoms, fluorine atoms, chlorine atoms, cyano groups or alkyl groups having 1 to 6 carbon atoms; Y can be 0, 1, or 2; A1 and A2 are each independently selected from the aromatic rings shown in the following structures: L3 and L4 are each independently selected from hydrogen atoms, fluorine atoms, chlorine atoms, cyano groups, or alkyl groups having 1 to 7 carbon atoms; A3 and A4 are each independently selected from the aromatic ring, hydrogenated quinoline ring, hydrogenated benzopyran ring, or hydrogenated naphthalene ring shown in the following structures, and at least one of A3 and A4 is a hydrogenated quinoline ring, a hydrogenated benzopyran ring, or a hydrogenated naphthalene ring: R1, R2, R3, R4, R6, and R7 are each independently selected from hydrogen atoms or alkyl groups having 1 to 7 carbon atoms; R5 is a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or an ethyl group; R8 is represented by a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, -NHR9, or -N(R9)2; and R9 is represented by an alkyl group having 1 to 10 carbon atoms.

2. The dichroic dye as described in claim 1, characterized in that, W represents a sulfur atom, and A1 and A2 are each independently selected from a benzene ring, a thiophene ring, or a fused thiophene ring.

3. The dichroic dye as described in claim 2, characterized in that, Selected from general structural formulas I-1 to I-16:

4. A liquid crystal composition, characterized in that, It includes the dichroic dye as described in any one of claims 1 to 3, and one or more liquid crystal compounds.

5. The liquid crystal composition according to claim 4, characterized in that, The liquid crystal composition also includes one or more chiral compounds.

6. The liquid crystal composition according to claim 4, characterized in that, The liquid crystal composition also includes one or more heat stabilizers or light stabilizers.

7. The liquid crystal composition according to claim 4, characterized in that, The liquid crystal compound is selected from the liquid crystal compound shown in general formula II: In Formula II: R is an alkyl group with 1 to 10 carbon atoms, an alkoxy group with 1 to 10 carbon atoms, an alkenyl group with 2 to 10 carbon atoms, or a cycloalkyl group with 3 to 6 carbon atoms; Ring A, ring B, and ring C are each independently selected from cyclohexane, cyclohexene, benzene ring, tetrahydropyran ring, or benzene ring in which hydrogen atoms are replaced by fluorine. X0 is hydrogen, fluorine, chlorine, cyano, trifluoromethoxy, trifluoromethyl, alkyl with 1 to 10 carbon atoms, alkoxy with 1 to 10 carbon atoms, alkenyl with 2 to 10 carbon atoms, or cycloalkyl with 3 to 6 carbon atoms; X1, X2, and X3 are each independently either hydrogen or fluorine; X4 is a single bond, -COO-, -CH2CH2-, or -CF2O-; k, p, and q can each independently take values ​​of 0, 1, and 2, and k + p + q ≥ 1.

8. The liquid crystal composition according to claim 7, characterized in that, The liquid crystal compound is selected from the liquid crystal compound shown in general formula III: In Formula III: R' is an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a cycloalkyl group having 3 to 6 carbon atoms; Ring A is cyclohexane, cyclohexene, benzene ring, tetrahydropyran ring, or benzene ring in which hydrogen atoms are replaced by fluorine. x0' is hydrogen, fluorine, chlorine, cyano, trifluoromethoxy, trifluoromethyl, alkyl with 1 to 10 carbon atoms, alkoxy with 1 to 10 carbon atoms, alkenyl with 2 to 10 carbon atoms, or cycloalkyl with 3 to 6 carbon atoms; x4' represents a single bond, -COO-, -CH2CH2-, -CF2O-, or -CH2O-. x5' represents an oxygen atom or a sulfur atom; k represents 0, 1, or 2.

9. The liquid crystal composition according to claim 4, characterized in that, The liquid crystal composition contains 0.1% to 10% by mass of dichroic dye, 80% to 99.9% by mass of liquid crystal compound represented by general structural formula II, and 0% to 20% by mass of liquid crystal compound represented by general structural formula III.

10. The liquid crystal composition according to claim 5, characterized in that, In this liquid crystal composition, the chiral compound has a mass percentage of 0.01–5%.

11. The liquid crystal composition according to claim 6, characterized in that, In this liquid crystal composition, the mass percentage of heat stabilizer or light stabilizer is 0.001 to 1%.

12. The use of the liquid crystal composition according to any one of claims 4 to 11 in the preparation of a dimming glass device.

13. A dimming glass device, characterized in that, The raw materials for preparing the dimming glass device include the liquid crystal composition according to any one of claims 4 to 11.

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