Organic compound and application thereof

Abstract

The invention discloses an organic compound and application thereof. The organic compound has a structure as shown in a formula I. In the formula I, R1 and R2 represent C1-C15 straight-chain, branched-chain alkyl or alkoxy in a same or different manner at each occurrence, and R1 and R2 represent C1-C15 straight-chain, branched-chain alkyl or alkoxy at each occurrence. Wherein any one or more disconnected-CH2-can be replaced by cyclopropylidene, cyclobutyl, cyclopentadiene or cyclopentadiene,-CH = CH-,-N (Re)-,-O-,-S-,-CO-,-CO-O-and-O-CO-in a form that O-or S-is not connected with each other, and at least one-CH2-in R1 and R2 is replaced by cyclopropylidene, cyclobutyl, cyclopentadiene or cyclopentadiene. The organic compound structure has the characteristics of low melting point, good low-temperature solubility and small normal temperature-high temperature contrast change rate. The liquid crystal material can be uniformly mixed with mixed crystals and completely dissolved at a relatively low processing temperature, and the risk of thermal decomposition or phase change of the liquid crystal material can be reduced. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the technical field of display materials. More specifically, it relates to an organic compound and its application. Background Art

[0002] Liquid crystal dyes are functional dyes used for color display in liquid crystal displays. It mainly utilizes the principle of combining the directional absorption of light by dye molecules with the characteristic of the directional arrangement of dye molecules in the liquid crystal changing with the electric field. By doping dichroic dye molecules in the host liquid crystal, the interaction between the host liquid crystal molecules and the dichroic dye molecules enables the dye molecules to follow the host liquid crystal molecules for ordered arrangement. When driven by an external electric field, the dichroic dye molecules rotate with the rotation of the host liquid crystal molecules. Since dichroic dye molecules are usually rod-shaped, the absorption ability of light in the long-axis and short-axis directions is different. When its direction changes with the rotation of the host liquid crystal molecules, the overall light absorption ability of the dye liquid crystal also changes accordingly, thus achieving electrochromic, color display and other effects.

[0003] In recent years, with people's continuous pursuit of a higher quality of life, the application fields of dye liquid crystals have been continuously expanding, such as the color-changing sunroofs of cars, the color-changing glass inside and outside buildings, the color-changing side windows on large public transportation vehicles, and smart glasses that change color with the intensity of external light.

[0004] Currently, the melting point of highly reliable dyes needs to be further reduced. In the prior art, typical dichroic dyes mainly include dyes such as anthraquinone, azo, and benzothiadiazole. Among them, anthraquinone dyes have good light stability, but their low linearity of disc-shaped structure molecules leads to low solubility; azo dyes have a relatively large dichroic ratio, but they are prone to fading in an ultraviolet light environment and have poor light stability; common benzothiadiazole dyes have good reliability, but their melting points are relatively high. In order to ensure complete dissolution during the mixing process with liquid crystals, the processing temperature needs to be increased for monomers with high melting points, which may cause thermal decomposition or phase change of the liquid crystal material, increasing the process complexity and cost. While low-melting-point dyes can be uniformly combined with the liquid crystal material at a relatively low temperature during the mixing process. Secondly, during the repeated heating and cooling process of the equipment, low-melting-point dyes can maintain a stable liquid state, reducing the risk of material fatigue or interface separation caused by phase change.

[0005] In addition, the low-temperature solubility of highly reliable dyes needs to be further improved. Currently, dye liquid crystals are increasingly used in fields such as construction, transportation, and wearable products. These applications require dye liquid crystals to have a wide temperature range of use to ensure their normal operation at high and low temperatures. Generally, the solubility of dyes has no problem in terms of high-temperature application, so the main limitation to their application is the solubility of dye monomers at low temperatures. Liquid crystal displays (such as automotive displays or outdoor devices) may operate at extremely low temperatures (such as below -30 °C). In guest-host liquid crystal displays (GH-LCDs), dyes and liquid crystal molecules need to be arranged cooperatively to achieve color changes. If the solubility of the dye is insufficient at low temperatures, it will precipitate from the liquid crystal, and the precipitated dye will disrupt this cooperative effect, resulting in uneven display, color spots, or a decrease in contrast. In addition, to expand the application of dyes in the market, dye liquid crystal technology needs to be applicable to special low-temperature environments such as cold regions, aerospace, etc. All these put forward higher requirements for the low-temperature solubility of highly reliable dyes.

[0006] The contrast change rate of highly reliable dyes at normal to high temperatures needs to be further improved. In recent years, the application of dichroic dyes has become increasingly widespread. Researchers have gradually applied dichroic dyes to liquid crystal display devices in TN or VA modes to improve the color characteristics or viewing angles of display devices and achieve the goals of higher contrast and brightness of display devices. For example, in emerging fields such as virtual reality (VR) and augmented reality (AR), in order to achieve a more realistic immersive experience and better visual effects, display technologies with extremely high contrast are required. In addition, the expansion of application scenarios also puts forward higher requirements for the contrast of dye liquid crystals. Moreover, the contrast of products needs to maintain a relatively high contrast at high temperatures to meet different needs. For example, the dimming element windows used in automobiles need to further improve their high contrast to adapt to different temperature conditions, ensure driving safety, and provide a better user experience. For example, under continuous exposure to the sun in summer, the temperature of the car window can reach above 60 °C, and some can even reach about 85 °C. As the temperature increases, the contrast of the dye will show a downward trend. How to ensure a relatively high contrast at high temperatures, that is, a low change rate from normal to high temperatures, is one of the technical problems that urgently need to be solved for current dye monomers.

[0007] Although existing thiadiazole dyes have many advantages in terms of high reliability, they do face some challenges in their applications due to their high melting points, relatively poor low-temperature solubility, and large contrast changes under room temperature to high-temperature conditions.

[0008] For example, CN105377995A discloses the following formula compound for dye liquid crystals:

[0009]

[0010] When the above-mentioned liquid crystal composition containing dyes is applied in the examples, compared with the comparative perylene dyes, they improve the anisotropy at 20 °C and the solubility at 20 °C, and to a certain extent improve the performance of the display device. However, the solubility of such structures at low temperatures, especially at -40 °C, is relatively insufficient, resulting in the precipitation of such thiadiazole dyes at low temperatures, thus causing abnormal display of the display device. Secondly, such compounds also have the problem of high melting point, which causes many inconveniences in the process of mixed crystal processing. At high temperatures, the change rate of its contrast with the increase of temperature is relatively large, which easily affects the display performance of the product.

[0011] For example, CN107580622A discloses the following formula compound for dye liquid crystal:

[0012]

[0013] The above-mentioned thiadiazoloquinoxaline compounds have excellent properties in terms of anisotropy (20 °C) and solubility in the liquid crystal medium (20 °C). Compared with perylene dyes, their characteristic absorption bands are narrower and there are no bands in the range of 500 - 550 nm, and significantly better color saturation can be achieved. However, the solubility of such compounds at low temperatures, especially at -40 °C, is seriously insufficient, resulting in the easy precipitation of such thiadiazoloquinoxaline compounds at low temperatures, affecting the normal display of the display device. In addition, due to its high melting point and large change rate of contrast at room temperature - high temperature, its market application is severely limited.

[0014] For example, CN113166652A discloses the following formula compound for dye liquid crystal:

[0015]

[0016] The above compounds all have sufficient solubility under the reference examples (at 20 °C) and individually exhibit sufficient stability in the daylight experiment, but there are still challenges in harsh low-temperature conditions and maintaining the change rate of contrast at room temperature - high temperature.

[0017] Therefore, with the continuous improvement of the requirements for low melting point, good low-temperature solubility and small change rate of contrast at room temperature - high temperature of dye monomers in dye-containing devices, there is still an urgent need to improve the performance of dye monomers, that is, to develop dyes with low melting point, excellent low-temperature solubility and small change rate of contrast at room temperature - high temperature to meet the growing market demand. Summary of the Invention

[0018] Aiming at the deficiencies of the prior art, the present invention provides a new technical solution, which can improve or solve the above problems.

[0019] Specifically, the present invention provides an organic compound and its applications. The organic compound has dichroism and can be used as a dichroic dye. The sub-cyclopropyl, sub-cyclobutyl, sub-cyclopentyl or sub-cyclopentenyl contained in the structure of the organic compound, in combination with its specific main structure, endows it with the characteristics of low melting point, good solubility at low temperature, and small change rate of contrast at normal temperature - high temperature. When used as a dichroic dye, the organic compound can be used to manufacture products such as dimming films, dimming glasses, liquid crystal display elements or liquid crystal displays.

[0020] To achieve the above object, the present invention adopts the following technical solutions:

[0021] On the one hand, the present invention provides an organic compound having a structure shown in the following formula I:

[0022]

[0023] Wherein,

[0024] each independently represents an aromatic ring, a heteroaromatic ring, or a fused ring, and any position thereof can be substituted by at least one L, and each L independently represents -F, -Cl, a straight-chain, branched-chain or cyclic alkyl group having 1 to 15 carbon atoms, wherein one or more non-adjacent -CH2- groups in the straight-chain, branched-chain or cyclic alkyl group having 1 to 15 carbon atoms can be independently replaced by -CH=CH-, -O-, -CO-, -CO-O- or -O-CO-, and one or more -H atoms can be independently replaced by -F or -Cl;

[0025] represents

[0026] R1 and R2, each time they appear, are the same or different and represent a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-connected -CH2- groups can be replaced by sub-cyclopropyl, sub-cyclobutyl, sub-cyclopentyl or sub-cyclopentenyl, -CH=CH-, -N(R e )-, -O-, -S-, -CO-, -CO-O-, -O-CO- in the form of O- or S- not connected to each other. Additionally, one or more H atoms can be replaced by F or Cl, and in R1 and R2, at least one -CH2- group is replaced by sub-cyclopropyl, sub-cyclobutyl, sub-cyclopentyl or sub-cyclopentenyl;

[0027] R a 、R b 、R c 、R d 、R erepresents, identically or differently each time it appears, -H, -F, -Cl, a linear or branched alkyl or alkoxy group having 1 to 15 carbon atoms, and wherein any one or more non-adjacent -CH2- groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO- in a form where O and S are not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F or Cl;

[0028] m1 and m2 each independently represent 0 or 1.

[0029] In a second aspect, the present invention provides a dichroic dye, which is prepared from the organic compound described in the first aspect.

[0030] In a third aspect, the present invention provides the use of the organic compound described in the first aspect above in the preparation of a light modulating element.

[0031] The beneficial effects of the present invention are as follows:

[0032] In the technical solution of the present invention, the organic compound represented by Formula I is a dichroic dye. Compared with existing benzothiadiazole and its derivatives, the organic compound represented by Formula I containing a specific cyclic structure in the present invention has characteristics such as a low melting point, good low-temperature solubility, and a very small change rate of the contrast ratio from room temperature to high temperature. In particular, due to the low melting point of the compound represented by Formula I, it can be uniformly mixed and completely dissolved with the mixed crystal at a relatively low processing temperature, reducing the risk of thermal decomposition or phase change of the liquid crystal material. Such dichroic dyes can be used to manufacture products such as light modulating films, light modulating glasses, liquid crystal display elements, or liquid crystal displays. Description of the Drawings

[0033] The following further describes in detail the specific embodiments of the present invention in conjunction with the drawings.

[0034] Figure 1 Shows the MS mass spectrum of the organic compound represented by Formula I-2-16.

[0035] Figure 2 Shows the MS mass spectrum of the organic compound represented by Formula I-1-2.

[0036] Figure 3 Shows the MS mass spectrum of the organic compound represented by Formula I-3-1.

[0037] Figure 4 Shows the MS mass spectrum of the organic compound represented by Formula I-2-1.

[0038] Figure 5 Shows the MS mass spectrum of the organic compound represented by Formula I-4-2. Detailed Description of the Embodiments

[0039] To illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments and the accompanying drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the specific content described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0040] According to a specific embodiment of the present invention, an organic compound is provided, and the organic compound has a structure shown in the following formula I:

[0041]

[0042] Wherein,

[0043] each independently represents an aromatic ring, a heteroaromatic ring, or a fused ring, and any position thereof may be substituted by at least one L, and each L independently represents -F, -Cl, a linear, branched, or cyclic alkyl group having 1 to 15 carbon atoms, wherein one or more non-adjacent -CH2- in the linear, branched, or cyclic alkyl group having 1 to 15 carbon atoms may be independently substituted by -CH=CH-, -O-, -CO-, -CO-O-, or -O-CO-, and one or more -H may be independently substituted by -F or -Cl;

[0044] represents

[0045] R1 and R2, each time they appear, are the same or different and represent a linear, branched alkyl group or an alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-connected -CH2- may be substituted by cyclopropylidene, cyclobutylidene, cyclopentylidene, or cyclopentene, -CH=CH-, -N(R e )-, -O-, -S-, -CO-, -CO-O-, -O-CO- in a form where O- or S- are not connected to each other. Additionally, one or more H atoms may be substituted by F or Cl, and in R1 and R2, at least one -CH2- is substituted by cyclopropylidene, cyclobutylidene, cyclopentylidene, or cyclopentenyl;

[0046] R a 、R b 、R c 、R d 、R erepresents, each occurrence being the same or different, -H, -F, -Cl, a linear, branched alkyl or alkoxy group having 1 to 15 carbon atoms, and wherein any one or more non-adjacent -CH2- may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO- in a form where O- and S- are not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F or Cl;

[0047] m1 and m2 each independently represent 0 or 1.

[0048] In some examples, the each independently represent 1,4-phenylene thiophene-2,5-diyl or thieno[3,2-b]thiophene-2,5-diyl wherein one or more H atoms may be replaced by L.

[0049] In some examples, the R1 and R2, each occurrence being the same or different, represent a linear, branched alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentene, -N(R e )-, -O-, -CH=CH- in a form where O- are not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F, and wherein at least one -CH2- is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentene.

[0050] In some examples, the R a , R b , R c , R d , R e each occurrence being the same or different, represent -H, a linear, branched alkyl or alkoxy group having 1 to 15 carbon atoms, wherein, additionally, any one or more non-adjacent -CH2- may be replaced by O-, -CO-, -CO-O- or -O-CO- in a form where -O- are not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F.

[0051] In some examples, the organic compound is selected from the group consisting of compounds represented by the following formulas:

[0052]

[0053] wherein,

[0054] a represents 0, 1 or 2;

[0055] each occurrence being the same or different, represents

[0056] L, each occurrence being the same or different, represents -F, a linear, branched or cyclic alkyl group having 1 to 15 carbon atoms;

[0057] R1 and R2, each occurrence being the same or different, represent a linear, branched alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- groups may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentene, -N(R e )-, -O-, -CH=CH- in a form where the O atoms are not connected to each other, and wherein, additionally, one or more H atoms may be replaced by F, and wherein at least one -CH2- group is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentene;

[0058] R a 、R b 、R c 、R d 、R e , each occurrence being the same or different, represent -H, a linear, branched alkyl or alkoxy group having 1 to 15 carbon atoms, wherein, additionally, any one or more non-adjacent -CH2- groups may be replaced by -O- in a form where the O atoms are not connected to each other, and wherein, additionally, one or more H atoms may be replaced by F.

[0059] In some examples, a represents 0 or 1, , each occurrence being the same or different, represents

[0060] R1 and R2, each occurrence being the same or different, represent a linear, branched alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- groups may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentene, -N(R e )-, -O-, -CH=CH- in a form where the O atoms are not connected to each other, and wherein, additionally, one or more H atoms may be replaced by F, and wherein at least one -CH2- group is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentene;

[0061] R a 、R b represent -H;

[0062] R c 、R d , each occurrence being the same or different, represent -H, -F, a linear, branched alkyl or alkoxy group having 1 to 15 carbon atoms;

[0063] R eRepresents, identically or differently each time it appears, -H, a straight-chain, branched alkyl or alkoxy group having 1 to 15 carbon atoms.

[0064] In the above examples, Compounds of Formulae I-1 to I-5 are all compounds containing a cyclic structure (cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentene).

[0065] Among them, the compound with the structure shown in Formula I-1 is a dye with a color in the yellow range, and its color will shift slightly with the change of the end group. It contains a thiadiazole and a biphenyl structure, has the best molecular linearity, the highest transmittance, the relatively smallest change rate of contrast from normal temperature to high temperature, and can achieve a brightening effect in the dye mixed crystal. Its application concentration is generally 0.5-3%.

[0066] The compound with the structure shown in Formula I-2 is a dye with a color in the red range, and its color will shift slightly with the change of the end group. It contains a thiadiazole and a symmetric thiophene ring structure, has a relatively wide absorption wavelength, the relatively highest contrast, and the relatively best solubility. Its application concentration is generally 0.5-3.5%.

[0067] The compound with the structure shown in Formula I-3 is a dye with a color in the green range, and its color will shift slightly with the change of the end group. It contains a thiadiazole quinoxaline and a symmetric thiophene ring structure, has the relatively lowest melting point, and its application concentration is generally 0.5-2%.

[0068] The compound with the structure shown in Formula I-4 is a dye with a color in the blue range, and its color will shift slightly with the change of the end group. It contains a thiadiazole and a symmetric thiophenothiophene ring structure, has the relatively best color saturation, and its application concentration is generally 0.5-3%.

[0069] The compound with the structure shown in Formula I-5 is a dye with a color in the blue-green range, and its color will shift slightly with the change of the end group. It contains a thiadiazole quinoxaline and a symmetric thiophenothiophene ring structure, has the relatively largest molecular cloud density and the relatively longest absorption wavelength, and its application concentration is generally 0.5-2%.

[0070] In some specific examples, the organic compound is selected from any one of the following compounds:

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083] In some preferred examples, the organic compound is selected from any one of the following compounds:

[0084]

[0085]

[0086]

[0087]

[0088] According to yet another specific embodiment of the present invention, a dichroic dye is provided, and the dichroic dye is prepared from the organic compound as described above.

[0089] According to yet another specific embodiment of the present invention, an application of the organic compound as described above in preparing a dimming element is provided.

[0090] Exemplarily, the dimming element includes but is not limited to a dimming film, dimming glass, liquid crystal display element or liquid crystal display.

[0091] Exemplarily, the application includes the following steps: adding the organic compound to a host liquid crystal, and mixing uniformly to obtain a liquid crystal composition.

[0092] Exemplarily, based on the total mass percentage of the host liquid crystal, the addition amount of the organic compound is 1-5%, preferably 2-5%, more preferably 2-3%.

[0093] The host liquid crystal may contain common liquid crystal monomers, which will not be elaborated here.

[0094] Examples

[0095] The technical solutions of the present invention will be described below in conjunction with some specific examples.

[0096] In the following examples and comparative examples, the methods involved are all conventional methods unless otherwise specified. The raw materials used can be obtained from public commercial channels unless otherwise specified. Percentages are all by mass, and the temperature is in degrees Celsius (°C).

[0097] I. Conditions for performance testing and specific meanings of corresponding symbols:

[0098] Cp represents the clearing point of the liquid crystal (°C), tested by DSC quantitative method;

[0099] Δn represents the optical anisotropy, Δn = ne - no, where no is the refractive index of the ordinary light and ne is the refractive index of the extraordinary light. The test conditions are 25 ± 2 °C, 589 nm, tested by an Abbe refractometer;

[0100] Δε represents the dielectric anisotropy, Δε = ε∥ - ε⊥, where ε∥ is the dielectric constant parallel to the molecular axis and ε⊥ is the dielectric constant perpendicular to the molecular axis. The test conditions are 25 ± 0.5 °C, 20 - micron antiparallel cell, tested by INSTEC: ALCT - CUST - 4C;

[0101] LTS represents the low - temperature stability, measured in the test unit.

[0102] DSC melting point test method:

[0103] DSC test melting point method: Instrument name: Differential Scanning Calorimeter; Manufacturer model: TA Q20 from the United States; Purge gas: 50 mL / min; Protection gas: 50 mL / min; Initial temperature 30 °C, termination temperature 300 °C, heating rate: 10 °C / min; Sample weight 2 mg; Crucible type: TA aluminum crucible.

[0104] Solubility and contrast test methods:

[0105] Solubility test: After adding the organic compounds of the examples and comparative examples to the host liquid crystal at a concentration of 2 wt% or 3 wt%, heat and stir at 120 °C for 1 h, mix and stir evenly in a glass bottle (bulk), store at - 40 °C, and observe every day whether crystals precipitate. At the same time, pour the dissolved liquid crystal into a TN - 7.0 - μm test cell (cell), seal it and also store it at - 40 °C, and observe every day whether crystals precipitate in the test cell to determine the dissolution at different low temperatures.

[0106] Contrast test: The compound shown in Formula I and a comparative organic compound D were separately added to the matrix liquid crystal as control samples. Then, a TN-7.0μm test cell was dot-sheeted and sent for DMS testing. The voltage-transmittance curves at 380 nm to 800 nm were measured at 0 V and 10 V voltages to obtain the transmittances at 0 V and 10 V. According to the formula contrast CR = transmittance at 10 V / transmittance at 0 V, the contrast CR of the corresponding dye compound in the matrix liquid crystal was obtained. The contrasts of the samples in Examples and Comparative Examples were measured and calculated at room temperature of 25 °C and high temperature of 85 °C. Finally, the change rate of the sample's contrast from room temperature to high temperature was calculated through the formula: change rate of the sample's contrast from room temperature to high temperature = (sample contrast (25 °C) - sample contrast (85 °C)) / sample contrast (25 °C)

[0107] II. Performance and preparation methods of organic compounds in each example and comparative example in the matrix liquid crystal:

[0108] Mixing and melting the organic compound (dichroic dye) with the structure shown in Formula I together with the remaining raw materials (matrix liquid crystal), or first melting and uniformly mixing the remaining raw materials except the dichroic dye, and then adding the dichroic dye, has no effect on the performance of the obtained liquid crystal composition. However, for the convenience of comparison, the liquid crystal compositions in the following examples and comparative examples are all prepared by the following method during the preparation process:

[0109] Weigh the remaining raw materials except the dichroic dye according to a certain ratio and put them into a stainless steel beaker. Then, place the beaker on a magnetic stirring instrument and heat it to melt. After the raw materials in the stainless steel beaker are completely melted, add a magnetic rotor to the stainless steel beaker and stir the mixture evenly to obtain the matrix liquid crystal; add the dichroic dye to the matrix liquid crystal. After the added dichroic dye is completely melted and mixed evenly, cool it to room temperature to obtain the liquid crystal composition.

[0110] The matrix liquid crystal was tested for properties such as Cp, Δn, Δε, and LTS using the above method, and the organic compound with the structure shown in Formula I was tested for properties such as DSC melting point, solubility, and contrast.

[0111] The organic compound with the structure shown in Formula I in the present invention can be synthesized by the following synthetic route:

[0112] Compound synthesis example

[0113] Example 1

[0114] This example provides an organic compound with the structure shown in Formula I-1-1, and the synthetic route of this compound is as follows:

[0115]

[0116] Step (1)

[0117]

[0118] Add 3'-fluorobiphenylol (30 g), potassium carbonate (26 g), bromobutane (26 g) and DMF (200 ml) to a three-necked flask. Heat to 120 °C and react for 2 hours. Pour the reaction system into water to precipitate a solid. Filter by suction. Recrystallize the solid with petroleum ether and freeze it at -20 °C for 3 hours. Filter by suction and dry the solid. Add the solid to another three-necked flask, add 250 ml of THF, protect with nitrogen, cool to -78 °C, dropwise add n-butyllithium (76 ml), keep the temperature and stir for 1 hour. Dissolve 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (29 g, 0.156 mol) in THF (100 ml), dropwise add it to the above system, warm to room temperature and stir. After the reaction is completed, pour it into water, extract with ethyl acetate, wash the organic layer twice with saturated sodium chloride aqueous solution, dry with anhydrous sodium sulfate to obtain a crude oil product. Recrystallize with 2 times of ethanol and freeze it at -20 °C for 4 hours to precipitate a solid of the compound shown in Formula I-A (41 g, 0.1 mol, 75%);

[0119] Step (2)

[0120]

[0121] Add 2-fluoro-4-bromobenzyloxycyclopentane (30 g, 0.1 mol), thiophene-2-boronic acid (29.2 g, 0.1 mol) and potassium carbonate (13.8 g, 0.15), and add toluene (300 ml), water (50 ml). Protect with nitrogen and add tetrakis(triphenylphosphine)palladium (0.2 g). Heat to reflux for 3 hours. After the reaction is completed, cool the system. Wash the organic layer twice with saturated sodium chloride aqueous solution, dry with anhydrous sodium sulfate, and rotary evaporate to obtain an oil. Add it to another three-necked flask, add THF (200 ml), protect with nitrogen, cool to -78 °C, dropwise add n-butyllithium (48 ml), keep the temperature and react for 1 hour. Dissolve 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (29 g, 0.156 mol) in THF (100 ml), dropwise add it to the above system, warm to room temperature and stir. After the reaction is completed, pour it into water, extract with ethyl acetate, wash the organic layer twice with saturated sodium chloride aqueous solution, dry with anhydrous sodium sulfate to obtain a crude oil product. Recrystallize with 2 times of ethanol and freeze it at -20 °C for 4 hours to precipitate a solid of the compound shown in Formula I-B (41 g, 0.1 mol, 75%);

[0122] Step (3)

[0123]

[0124] Add I-B (30 g, 0.1 mol), 4,7-dibromo-2,1,3-benzothiadiazole (29.2 g, 0.1 mol) and potassium carbonate (13.8 g, 0.15) to a three-necked flask, add 300 ml of toluene and 50 ml of water, add 0.2 g of tetrakis(triphenylphosphine)palladium under nitrogen protection, heat to reflux for 3 hours, cool the reaction system after completion, wash the organic layer twice with saturated sodium chloride aqueous solution, dry with anhydrous sodium sulfate, purify the crude product through a chromatographic column (SiO2, petroleum ether: ethyl acetate 10:1), and then recrystallize with ethanol to obtain the compound shown in formula I-C (21 g, 0.045 mol, 44.9%);

[0125] Step (4)

[0126]

[0127] Operate with reference to step 3) to obtain the organic compound shown in formula I-1-1.

[0128] Example 2

[0129]

[0130] Step (1)

[0131]

[0132] Add 4'-butoxybiphenylboronic acid (30 g, 0.1 mol), 4,7-dibromo-2,1,3-benzothiadiazole (29.2 g, 0.1 mol) and potassium carbonate (13.8 g, 0.15) to a three-necked flask, add 300 ml of toluene and 50 ml of water, add 0.2 g of tetrakis(triphenylphosphine)palladium under nitrogen protection, heat to reflux for 3 hours, cool the reaction system after completion, wash the organic layer twice with saturated sodium chloride aqueous solution, dry with anhydrous sodium sulfate, purify the crude product through a chromatographic column (SiO2, petroleum ether: ethyl acetate 10:1), and then recrystallize with ethanol to obtain the compound shown in formula II-A (21 g, 0.045 mol, 44.9%);

[0133] Step (2)

[0134]

[0135] Add 3-cyclopentyl-1-bromopropane (30 g, 0.16 mol), p-bromophenol (27.1 g, 0.16 mol) and potassium carbonate (33.1 g, 0.24 mol) to a three-necked flask, and add DMF (300 ml). Heat the reaction mixture to 100 °C and react for 3 hours. After the reaction is completed, cool the system, pour it into water, extract with ethyl acetate, wash the organic layer twice with saturated sodium chloride aqueous solution, and dry over anhydrous sodium sulfate to obtain the compound shown in Formula II-B (42 g, 0.15 mol, 94.3%);

[0136] Step (3)

[0137]

[0138] Referring to the synthesis method of Step (1), synthesize the compound shown in Formula II-C to obtain an oily substance (38 g, 0.13 mol, 89.4%);

[0139] Step (4)

[0140]

[0141] Add II-C (38 g, 0.13 mol) to a three-necked flask, and add THF (300 ml). After replacing the nitrogen, cool the temperature to -78 °C, and dropwise add n-butyllithium (2.5 mol / L, 63 ml). After the addition is completed, keep stirring for 1 hour. Dissolve 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (29 g, 0.156 mol) in THF (100 ml), and dropwise add it to the above system. Warm the reaction mixture to room temperature and stir. After the reaction is completed, pour it into water, extract with ethyl acetate, wash the organic layer twice with saturated sodium chloride aqueous solution, and dry over anhydrous sodium sulfate to obtain a crude oil product. Recrystallize the crude oil product with 2-fold ethanol and freeze it at -20 °C for 4 hours to precipitate a solid compound shown in Formula II-D (41 g, 0.1 mol, 75%);

[0142] Step (5)

[0143]

[0144] Referring to the synthesis method of Step (1), synthesize the organic compound shown in Formula I-1-2 to obtain an orange solid (11.5 g, 0.017 mol, 38%).

[0145] Synthesize I-1-3; I-1-5; I-1-7; I-1-8; I-1-10 according to the synthesis method of Example 2.

[0146] Example 3

[0147]

[0148] Step (1)

[0149]

[0150] Add 3-fluoro-4-chlorobromobenzene (30 g, 0.15 mol) to a three-necked flask, and add THF (300 ml). Replace the gas with nitrogen three times, cool down to -78 °C, and dropwise add n-butyllithium (2.5 mol / L, 71 ml). After the addition, stir at the same temperature for 1 hour. Dissolve 2-ethylhexanal (20 g, 0.15 mol) in THF (100 ml), and dropwise add it to the above system. Warm to room temperature and stir. After the reaction is completed, pour it into water, extract with ethyl acetate. Wash the organic layer twice with saturated sodium chloride aqueous solution, dry over anhydrous sodium sulfate to obtain a crude oil product. Dissolve the crude product in THF (200 ml), cool down to -20 °C, dropwise add triethylsilane (20.5 g, 0.17 mol), then dropwise add boron trifluoride diethyl etherate (24.1 g, 0.17 mol). After the addition, stir at room temperature. After the reaction is completed, pour the system into water, extract with ethyl acetate. Wash the organic layer twice with saturated sodium chloride aqueous solution, dry over anhydrous sodium sulfate to obtain the compound shown in Formula III-A (28 g, 0.12 mol, 75%);

[0151] Step (2)

[0152]

[0153] Refer to Step 3 of Example 2 to synthesize the compound shown in Formula III-B (25 g, 0.09 mol, 75%);

[0154] Step (3)

[0155]

[0156] Refer to Step 4 of Example 2 to synthesize the compound shown in Formula III-C (25.2 g, 0.06 mol, 70%);

[0157] Step (4)

[0158]

[0159] (10 g, 0.05 mol) 3-Cyclopentyl-1-bromopropane was added to a three-necked flask, followed by the addition of magnesium turnings (4.5 g, 0.19 mol). One iodine crystal was added. After purging with nitrogen, the mixture was heated to reflux. After initiation, the remaining 3-cyclopentyl-1-bromopropane (20 g, 0.1 mol) was added dropwise to the reaction system. The reaction was maintained at a constant temperature for 1 hour and then cooled to room temperature. 3-Fluoro-4-bromobenzaldehyde (30 g, 0.15 mol) was dissolved in THF (100 ml) and added dropwise to the above system. The mixture was stirred for 30 minutes. After the reaction was completed, the system was poured into water, and the pH was adjusted to neutral with dilute hydrochloric acid. The mixture was extracted with ethyl acetate, dried over anhydrous sodium sulfate, and concentrated by rotary evaporation to obtain the crude product. The crude product was dissolved in THF (200 ml), cooled to -20 °C, and triethylsilane (21 g, 0.18 mol) was added dropwise, followed by the dropwise addition of boron trifluoride diethyl etherate (26 g, 0.18 mol). After the addition was complete, the mixture was stirred at room temperature. After the reaction was completed, the system was poured into water, extracted with ethyl acetate, and the organic layer was washed twice with saturated aqueous sodium chloride solution and dried over anhydrous sodium sulfate to obtain the compound shown in Formula III-D (31 g, 0.10 mol, 70%);

[0160] Step (5)

[0161]

[0162] Referring to Step 3 of Example 2, the compound shown in Formula III-E (24 g, 0.08 mol, 76%) was synthesized;

[0163] Step (6)

[0164]

[0165] Referring to Step 4 of Example 2, the compound shown in Formula III-F (26 g, 0.06 mol, 76%) was synthesized;

[0166] Step (7)

[0167]

[0168] Referring to Step 1 of Example 2, the compound shown in Formula III-G (13.2 g, 0.025 mol, 42%) was synthesized;

[0169] Step (8)

[0170]

[0171] Referring to the synthesis method of Step 1 of Example 2, III-C was used to synthesize I-2-1 (14 g, 0.02 mol, 76%)

[0172] Synthesized according to the synthesis method of the compound shown in Example 3: I-2-3; I-2-6; I-2-8; I-2-9.

[0173] Example 4

[0174]

[0175] Step (1)

[0176]

[0177] Synthesize IV-A (25 g, 0.09 mol, 70%) with reference to Step 3) of Example 2;

[0178] Step (2)

[0179]

[0180] Synthesize IV-B (30 g, 0.7 mol, 70%) with reference to Step 4) of Example 2;

[0181] Step (3)

[0182]

[0183] Add (10 g, 0.05 mol) 3-cyclopentyl-1-bromopropane to a three-necked flask, add N-butyl-4-bromoaniline (8 g, 0.035 mol), potassium carbonate (5.8 g, 0.04 mol) and DMF (100 ml), heat up to 100 °C and keep the reaction for 2 hours. After the reaction is completed, pour the system into ice water, extract with ethyl acetate, and dry to obtain IV-C (10 g, 0.03 mol, 85%);

[0184] Step (4)

[0185]

[0186] Synthesize IV-D (10 g, 0.02 mol, 72%) with reference to Step 4) of Example 2;

[0187] Step (5)

[0188]

[0189] Synthesize IV-E (5.5 g, 0.01 mol, 46.6%) with reference to Step 1) of Example 2;

[0190] Step (6)

[0191]

[0192] Refer to Step 1) of Example 2 to synthesize I-2-16 (5 g, 0.01 mol, 66%).

[0193] Example 5

[0194]

[0195] Step (1)

[0196]

[0197] Refer to Step 1) and Step 2) of Example 3 to synthesize V-A (15 g, 0.034 mol, 65%); Step (2)

[0198]

[0199] Refer to Step 1) and Step 2) of Example 3 to synthesize V-B (17 g, 0.035 mol, 61%); Step (3)

[0200]

[0201] Add 4,7-dibromobenzo[c][1,2,5]thiadiazole-5,6-diamine (30 g, 0.09 mol) to a three-necked flask, then add 3,4-hexanedione (12.3 g, 0.11 mol) and p-toluenesulfonic acid (0.5 g), as well as THF (200 ml). Heat to 50 °C and stir for 2 hours. After the reaction is completed, add the system to water and extract with ethyl acetate. Dry, evaporate to dryness and then triturate with petroleum ether. Filter to obtain solid V-C (28.5 g, 0.07 mol, 72%);

[0202] Step (3)

[0203]

[0204] Refer to Step 5) of Example 3 to synthesize V-D (10 g, 0.014 mol, 42%);

[0205] Step (4)

[0206]

[0207] Refer to Step 6) of Example 3 to synthesize I-3-6 (6.7 g, 0.007 mol, 50%).

[0208] Example 6

[0209]

[0210] Step (1)

[0211]

[0212] Add 2-bromothieno[3,2-b]thiophene (50 g, 0.23 mol), copper powder (2.9 g, 0.046 mol), cuprous iodide (14 g, 0.078 mol), and dibutylamine (36 g, 0.28 mol), as well as DMF (200 ml) to a three-necked flask. Heat to 120 °C and stir for 2 hours. After the reaction is completed, add the system to water and extract with ethyl acetate. Dry and rotary evaporate to purify the crude product through a chromatographic column (SiO2, petroleum ether: ethyl acetate 10:1) to obtain compound VI-A (25 g, 0.09 mol, 41%);

[0213] Step (2)

[0214]

[0215] Synthesize VI-B (28 g, 0.07 mol, 76%) by referring to step 4) of Example 2;

[0216] Step (3)

[0217]

[0218] Synthesize VI-C (100 g, 0.37 mol, 85%) by referring to step 3) of Example 4;

[0219] Step (4)

[0220]

[0221] Add Pd / C (5 g) to a three-necked flask, add THF (500 ml), then add I-5-C (100 g, 0.37 mol), displace with hydrogen 3 times, control the temperature at 50 °C and stir for 4 hours. Filter off Pd / C and rotary evaporate the solvent to obtain a colorless oil VI-D (60 g, 0.32 mol, 89.5%);

[0222] Step (5)

[0223]

[0224] Synthesize VI-E (32 g, 0.1 mol, 31%) by referring to step 1) of Example 6;

[0225] Step (6)

[0226]

[0227] Synthesize VI-F (28.5 g, 0.064 mol, 63.4%) by referring to step 2) of Example 6;

[0228] Step (7)

[0229]

[0230] Refer to Step 5) of Example 4 to synthesize VI-G (15.3 g, 0.03 mol, 45%);

[0231] Step (8)

[0232]

[0233] Similarly, referring to the synthesis method of Example 6, use VI-F and the structure of V-C in Example 5 to synthesize I-5-2 (15 g, 0.017 mol, 85%).

[0234] Refer to the synthesis method of Example 6 to synthesize: I-5-3; D-7.

[0235] Example 7

[0236]

[0237] Step (1)

[0238]

[0239] Add II-D (10 g, 0.02 mol), 4,7-dibromo-2,1,3-benzothiadiazole (3 g, 0.01 mol) and potassium carbonate (3.3 g, 0.024 mol) to a three-necked flask, add 100 ml of toluene and 20 ml of water, add 0.1 g of tetrakis(triphenylphosphine)palladium under nitrogen protection, heat to reflux for 3 hours, cool the reaction system after completion, wash the organic layer twice with saturated sodium chloride aqueous solution, dry with anhydrous sodium sulfate, purify the crude product through a chromatographic column (SiO2, petroleum ether: ethyl acetate 5:1), and then recrystallize with ethanol to obtain compound I-2-13 (6.3 g, 0.008 mol, 74%);

[0240] Refer to the synthesis method of Example 7 to synthesize: I-2-2; I-3-2; I-3-3; I-3-7; I-4-2; I-4-5; I-4-6; I-4-11.

[0241] Example 8

[0242]

[0243] Step (1)

[0244]

[0245] Add cyclopentyl bromopropane (2 g, 0.01 mol), magnesium chips (3 g, 0.13 mol), 1 iodine granule and THF (200 ml) to a three-necked flask. Under nitrogen protection, heat to reflux. After the reaction is initiated, dissolve cyclopentyl bromopropane (20 g) in THF and add it dropwise to the above system. Heat to reflux for 1 hour. After the reaction is completed, cool the system to room temperature. Then dissolve 3-fluoro-4-chlorobenzobutyrophenone (23 g, 0.115 mol) in THF and add it dropwise to the above system. Stir for 1 hour, pour into water to quench. Wash the organic layer twice with saturated sodium chloride aqueous solution, dry with anhydrous sodium sulfate. Dissolve the crude product in DCM, cool to -10 °C, dropwise add triethylsilane (16 g, 0.14 mol) and boron trifluoride diethyl etherate (19.8 g, 0.14 mol), stir and warm to room temperature, pour into water, extract with ethyl acetate, dry and pass through a column to obtain VIII-A (30 g, 0.1 mol, 88%);

[0246] Step (2)

[0247]

[0248] Refer to Step 3) of Example 2 to synthesize VIII-B (28 g, 0.08 mol, 80%);

[0249] Step (3)

[0250]

[0251] Refer to Step 4) of Example 2 to synthesize VIII-C (24 g, 0.05 mol, 63%);

[0252] Step (4)

[0253]

[0254] Refer to Step 1) of Example 7 to synthesize I-2-24 (24 g, 0.05 mol, 63%)

[0255] Reference Example 8 can also synthesize: I-2-4, I-2-5, I-3-5, I-3-11, I-4-1.

[0256] Example 9

[0257]

[0258] Step (1)

[0259] Add cyclopentyl bromopropane (2 g, 0.01 mol), magnesium chips (3 g, 0.13 mol), 1 iodine granule and THF (200 ml) to a three-necked flask. Under nitrogen protection, heat to reflux. After the reaction is initiated, dissolve cyclopentyl bromopropane (30 g) in THF and add it dropwise to the above system. Heat to reflux for 1 hour. After the reaction is completed, cool the system to room temperature. Then dissolve ethyl hexanoate (24 g, 0.16 mol) in THF and add it dropwise to the above system. Stir for 1 hour, pour it into water to quench, wash the organic layer twice with saturated sodium chloride aqueous solution, and obtain 25 g of intermediate by column chromatography. Add thiophene[3,2-b]thiophene (16 g, 0.12 mol) to THF (200 ml). Under nitrogen protection, cool to -78 °C and stir for 1 hour. Add the above intermediate dropwise to the above system, stir and warm back to room temperature. After the reaction is completed, pour it into water, extract with ethyl acetate, and purify by silica gel column to obtain intermediate 2 (32 g, 0.09 mol). Add intermediate 2 to THF, cool to -20 °C, dropwise add triethylsilane (12.7 g, 0.11 mol) and boron trifluoride diethyl etherate (15.6 g, 0.11 mol), stir and warm back to room temperature. After the reaction is completed, pour it into water, extract with ethyl acetate, dry and pass through a column to obtain IX-A (22 g, 0.06 mol, 72%).

[0260] Step (2)

[0261]

[0262] Refer to Step 2 of Example 6 to synthesize IX-B (20 g, 0.043 mol, 66.7%);

[0263] Step (3)

[0264]

[0265] Refer to the synthesis method in Step 5) of Example 4 to obtain I-5-1 (12 g, 0.132 mol, 60.9%).

[0266] In the above examples, the MS mass spectra of the compounds of formula I-1-2, I-2-1, I-2-16, I-3-1, and I-4-2 prepared are respectively as Figures 1 - 5 shown.

[0267] Determination of the properties of dichroic dyes

[0268] In order for the dye to play a better role in the mixed liquid crystal, it must have relatively low melting point, good solubility at low temperature, and small change rate of contrast at room temperature - high temperature. Therefore, the dye properties were studied by comparison from these aspects. The following monomer structures are given for comparison:

[0269]

[0270]

[0271] Table 1 Structures of Dye Compounds Involved in Examples and Comparative Examples

[0272]

[0273]

[0274]

[0275] Compared with the structures of the dye compounds involved in the comparative examples, the main ring structures of the corresponding examples are the same as those of the comparative examples, and the structural difference from the comparative examples is only that the end groups contain cyclic structures (sub-cyclopropyl, sub-cyclobutyl, sub-cyclopentyl, or sub-cyclopentenyl).

[0276] The parent liquid crystal (SLC) was prepared according to the above method, and the relevant actual liquid crystals were prepared by adding the structures of the dichroic dyes involved in the examples and comparative examples to the parent liquid crystal SLC-1. The specific composition formula and performance parameters of the parent liquid crystal SLC-1 are shown in Table 2 below. The mass percentage content of each liquid crystal structure is calculated based on the total content of each liquid crystal in the corresponding table being 100%.

[0277] Table 2 Composition and Performance Parameters of Parent Liquid Crystal SLC-1

[0278]

[0279] Table 3 DSC-related Data of Dichroic Dyes in Examples and Comparative Examples

[0280]

[0281]

[0282] Table 3 shows the DSC melting point data of the organic compounds in the relevant examples and comparative examples. Under the condition of the same main structure, the melting points measured by DSC of the examples with cyclic structure substitution and the prior art comparative examples without alkyl groups were analyzed. For those in the field of liquid crystal research and development, when the melting point of the dye monomer is 95 - 105 °C, a decrease in melting point by more than 5 °C is an obvious improvement. When the melting point of the dye monomer is 105 - 150 °C, a decrease in melting point by more than 10 °C is an obvious improvement. From the results, it can be seen that for the examples with cyclic structures having the same main structure compared with the comparative examples without cyclic structures, the melting point has decreased significantly. Specifically, the melting point temperature of the I-3 type monomers is the lowest, followed by the I-1 type monomers, I-2 type monomers, and I-5 type monomers. The melting point of the I-4 type monomers is relatively high, but compared with the comparative examples with only end group substitution but the same main structure, its melting point has been significantly improved.

[0283] Table 4 gives the dissolution data of the exemplary embodiments and comparative examples in the matrix liquid crystal SLC-1, where the dissolution stirring is 1 h for all. From the data in Table 4, it can be found that due to the low melting point of the compound shown in Formula I, it has the advantage of dissolution at a relatively low temperature. It can be uniformly mixed and completely dissolved with the mixed crystal at a relatively low processing temperature, reducing the risk of thermal decomposition or phase change of the liquid crystal material due to high temperature. Considering from a molecular perspective, it may be that the introduction of the cyclic structure breaks the stacking between molecules, making the compound shown in Formula I exhibit a lower melting point. In addition, the low melting point structure is more conducive to the monomer showing good solubility and higher low-temperature solubility in the formulation.

[0284] Table 4 Dissolution data of the exemplary embodiments and comparative examples in the matrix liquid crystal SLC-1 (stirring dissolution time: 1 h)

[0285]

[0286]

[0287] Table 5 Number of OK days at low temperature of the dichroic dyes of the embodiments and comparative examples

[0288]

[0289] Table 5 shows the low-temperature solubility data of the liquid crystal compositions obtained by adding the organic compounds of the relevant embodiments and comparative examples to the matrix liquid crystal SLC-1. The selected concentration is relatively large in the currently used system to facilitate obvious comparison between the embodiments and comparative examples. The concentration actually used is not limited to 3 wt% or 2 wt%. For those in the field of liquid crystal research and development, when the number of OK days of the dye liquid crystal is 5 to 20 days at -40 °C in bulk or cell, when the number of OK days at low temperature increases by more than 5 days, it can be considered that the solubility improvement is obvious. Under the condition of the same main structure, the number of OK days at -40 °C cell low temperature and -40 °C bulk low temperature of the embodiments with cyclic structure substitution and the prior art comparative examples without alkyl groups are analyzed. From the results, it can be seen that for the embodiments with cyclic structure and the same main structure, compared with the comparative examples without cyclic structure, their low-temperature solubility has been significantly improved. Specifically, the low-temperature solubility of the I-2 type monomers is the best, and the number of OK days at -40 °C cell low temperature and -40 °C bulk low temperature is the largest. Followed by the I-1 type monomers and I-4 type monomers. The solubility of the I-3 type monomers and I-5 type monomers is relatively poor, but there has also been a significant improvement compared with the comparative examples with the same main structure but without cyclic structure at the end groups.

[0290] Compared with the comparative example dye monomers having the same main structure, the corresponding example dye monomers containing a cyclic structure have a longer number of days with OK cell low temperature at -40°C and bulk low temperature at -40°C, and can ensure better low-temperature solubility and are not prone to precipitation. Corresponding to the previous DSC melting point data, the dichroic dyes containing a specific cyclic structure in the compound of formula I of the present invention exhibit better low-temperature solubility, can broaden the nematic phase range of the formulation, and are beneficial for the product to exhibit better performance in a more extreme environment without crystallization.

[0291] Table 6 shows the change rate of the normal temperature - high temperature contrast of the dichroic dyes in the parent liquid crystal SLC-1 in the examples and comparative examples: (wherein, the contrast change rate = (contrast at 25°C - contrast at 85°C) / contrast at 25°C)

[0292]

[0293]

[0294] Table 6 shows the data of the change rate of the normal temperature - high temperature contrast of the relevant examples and comparative examples. Under the condition of the same main structure, the change rate of the normal temperature - high temperature contrast data of the example containing a cyclic structure substitution and the prior art comparative example without an alkyl group was analyzed. For those in the field of liquid crystal research and development, when the contrast of the dye liquid crystal is within 1.00 - 1.20 (including the endpoints), the change rate of the normal temperature - high temperature contrast within 3.0% is considered acceptable. When the contrast of the dye liquid crystal is within 1.20 - 1.40 (excluding the endpoints), the change rate of the normal temperature - high temperature contrast within 5.0% is considered acceptable. When the contrast of the dye liquid crystal is within 1.40 - 1.80 (including the endpoints), the change rate of the normal temperature - high temperature contrast within 7.0% is considered acceptable. From the results, it can be seen that for the examples containing a cyclic structure with the same main structure compared with the comparative examples without a cyclic structure, the data of the change rate of the normal temperature - high temperature contrast has been significantly reduced. Specifically, the change rate of the normal temperature - high temperature contrast of the monomer of formula I-1 is relatively the lowest, followed by the monomers of formula I-3, the monomers of formula I-5, and the monomer of formula I-4. The change rate of the normal temperature - high temperature of the monomer of the structure shown in formula I-2 is slightly larger, but there has been a significant improvement compared with the comparative example having the same main structure but without a cyclic structure at the end group.

[0295] Compared with the dyes having the same main structure but without a cyclic structure, the dichroic dyes containing a cyclic structure in the present invention have the advantage of a low change rate of the contrast at normal temperature - high temperature. The reason may be that the compound molecules shown in formula I of the present invention can still maintain a relatively ordered arrangement at high temperature as at room temperature, ensuring its light modulation effect and maintaining its high contrast.

[0296] In summary, the sub-cyclopropyl, sub-cyclobutyl, sub-cyclopentyl or sub-cyclopentenyl groups contained in the structure of the organic compound of the present invention, in combination with its specific main structure, endow it with the characteristics of low melting point, good solubility at low temperature, and small change rate of contrast at normal temperature - high temperature. In particular, due to the low melting point of the compound of formula I, it can be uniformly mixed and completely dissolved with the mixed crystal at a relatively low processing temperature, reducing the risk of thermal decomposition or phase change of the liquid crystal material. As a dichroic dye, this organic compound can be used to manufacture products such as dimming films, dimming glasses, liquid crystal display elements or liquid crystal displays.

[0297] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or variations derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. An organic compound, characterized in that, The organic compound has a structure represented by the following formula I: Wherein, Each independently represents an aromatic ring, a heteroaromatic ring, or a fused ring, where any position can be substituted by at least one L, and each L independently represents -F, -Cl, a straight-chain, branched-chain, or cyclic alkyl group having 1 to 15 carbon atoms, where one or more than 2 non-adjacent -CH2- groups in the straight-chain, branched-chain, or cyclic alkyl group having 1 to 15 carbon atoms can be independently substituted by -CH=CH-, -O-, -CO-, -CO-O-, or -O-CO-, and one or more -H atoms can be independently substituted by -F or -Cl; indicate R1 and R2, each occurrence being the same or different, represent a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- groups may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentene, -CH=CH-, -N(R e )-, -O-, -S-, -CO-, -CO-O-, -O-CO- in a form where O and S are not connected to each other. Additionally, one or more H atoms may be replaced by F or Cl, and in R1 and R2, at least one -CH2- group is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentenyl; R a 、R b 、R c 、R d 、R e which, each time it appears, independently represents -H, -F, -Cl, a linear or branched alkyl or alkoxy group having 1 to 15 carbon atoms, and wherein any one or more non-adjacent -CH2- groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO- in such a way that O and S are not directly linked to each other, and wherein, additionally, one or more H atoms may be replaced by F or Cl; m1 and m2 each independently represent 0 or 1.

2. The organic compound according to claim 1, wherein The said each independently represents 1,4-phenylene, thiophene-2,5-diyl or thienothiophene-2,5-diyl, wherein one or more H atoms may be replaced by L.

3. The organic compound according to claim 2, wherein, R1 and R2, each occurrence being the same or different, represent a straight-chain, branched-chain alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- groups may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentenylene, -N(R e )-, -O-, -CH=CH- in a form where O atoms are not adjacent to each other, and wherein In addition, one or more H atoms may be replaced by F, and at least one -CH2- is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentenylidene.

4. The organic compound according to claim 3, wherein Said R a , R b , R c , R d , R e each appears the same or differently to represent -H, a straight-chain, branched alkyl or alkoxy group having 1 to 15 carbon atoms, wherein, additionally, one or more non-adjacent -CH2- may be replaced by O-, -CO-, -CO-O- or -O-CO- in a form where O- is not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F.

5. The organic compound according to claim 4, characterized in that, The organic compound is selected from the group consisting of compounds represented by the following formulas: Wherein, a represents 0, 1 or 2; Represent, identically or differently, each time it occurs L, each occurrence being the same or different, represents -F, a linear, branched or cyclic alkyl group having 1 to 15 carbon atoms; R1 and R2, each occurrence being the same or different, represent a straight-chain, branched alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- groups may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentene, -N(R e )-, -O-, -CH=CH- in a form where O atoms are not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F, and wherein at least one -CH2- group in R1 and R2 is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentene; R a 、R b 、R c 、R d 、R e which, each time it appears, independently represents -H, a linear, branched alkyl or alkoxy group having 1 to 15 carbon atoms, wherein, additionally, any one or more non-adjacent -CH2- groups may be replaced by -O- in a form where the O atoms are not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F.

6. The organic compound according to claim 5, wherein, wherein a represents 0 or 1, which represents the same or different each time it appears R1 and R2, each occurrence being the same or different, represent a straight-chain, branched alkyl or alkoxy group having 1 to 15 carbon atoms, wherein any one or more non-adjacent -CH2- may be replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentene, -N(R e )-, -O-, -CH=CH- in a form where O atoms are not adjacent to each other, and wherein, additionally, one or more H atoms may be replaced by F; wherein at least one -CH2- in R1 and R2 is replaced by cyclopropylidene, cyclobutylidene, cyclopentylidene or cyclopentene; R a 、R b represent -H; R c 、R d each independently represents, each time it appears, -H, -F, a linear or branched alkyl or alkoxy group having 1 to 15 carbon atoms; R e which, each time it appears, independently represents -H, a linear, branched alkyl or alkoxy group having 1 to 15 carbon atoms.

7. The organic compound according to claim 6, wherein, The organic compound is selected from any one of the following compounds:

8. The organic compound according to claim 7, wherein The organic compound is selected from any one of the following compounds:

9. A dichroic dye, characterized in that, Prepared from the organic compound according to any one of claims 1-8.

10. Use of the organic compound according to any one of claims 1-8 or the dichroic dye according to claim 9 in the preparation of a dimming element.

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