A benzotriazole dichroic dye and its application

Abstract

The present invention discloses a benzotriazole dichroic dye and its application. The dichroic dye uses benzotriazole as an acceptor unit, a benzene ring and thiophene or its derivatives as donor units, and has the structural formula #imgabs0#, wherein R1 represents C 1～8 Alkyl, Ar represents any one or any combination of #imgabs1##imgabs2#, n and m are each independently an integer of 1 to 3, R2 represents C 1～10 The dichroic dye of the present invention has a wide light absorption range and good stability, and can be used to prepare high-performance intelligent dimming windows.

Description

Technical Field

[0001] The invention belongs to the technical field of dichroic dyes, and in particular relates to a dichroic dye with a benzotriazole acceptor, a benzene ring and thiophene or a derivative thereof as a donor unit and application thereof. Background Art

[0002] With the continuous advancement and development of industrial technology worldwide, humanity's demand for energy is growing. Since the advent of industrial civilization, development has become highly dependent on fossil fuels. With the energy crisis and environmental degradation becoming increasingly serious, and with the continued advancement of national energy conservation and emission reduction efforts, a typical application direction is the use of smart windows in buildings and vehicles to replace traditional glass. Smart windows can automatically adjust the light transmittance based on the intensity of external light, thereby controlling the amount of sunlight entering the room through the windows and dynamically adjusting the indoor temperature, thereby reducing energy consumption for indoor temperature control equipment and lighting facilities (in-vehicle), and protecting indoor objects from UV damage. Smart windows, with their many advantages such as fast response time, low color distortion, high contrast, wide viewing angle, and low driving voltage, have become the core of this research.

[0003] The main types of switchable glass currently under research include polymer dispersed liquid crystal (PDLC), electrochromic (EC), suspended particle device (SPD), and dichroic dye liquid crystal (Dye LC). PDLC, SPD, and EC have been developed for many years. PDLC can only switch between transparent and hazy, but does not block light or insulate heat. EC also suffers from complex film processing, slow response time, and a distorted blue dark state.

[0004] To date, the most widely studied dichroic dyes include azo and anthraquinone dyes. The linear structure of azo dyes complements well with the structure of the host liquid crystal (generally rod-shaped). Monoazo dyes were initially synthesized, but later disazo and trisazo dyes were discovered to have higher order parameters. The introduction of heterocycles can improve optoelectronic properties, thermodynamic performance, and solubility, but the downside is optical instability. Anthraquinone dyes offer greater light resistance and stability than azo dyes. Although their color is weaker than that of azo dyes, the color range can be expanded by introducing different substituents into the matrix. However, their large size, significantly different from the common rod-shaped liquid crystal molecular structure, prevents them from dissolving well in the host liquid crystal, resulting in a low order parameter. Although a variety of dichroic liquid crystal tunable smart windows are now commercially available, existing color-changing smart windows are not sufficiently intelligent because most color-changing materials struggle to achieve zero transmission across the entire visible spectrum (380-780 nm), allowing light to pass through the window. Summary of the Invention

[0005] The purpose of the present invention is to provide a benzotriazole dichroic dye which has strong absorption of visible light, achieves zero transmission of visible light around 400 nm, and has strong stability, as well as the use of the dichroic dye.

[0006] For the above purpose, the structural formula of the benzotriazole dichroic dye provided by the present invention is as follows:

[0007]

[0008] Where R1 represents C 1～8 Alkyl, Ar represents Any one or any combination of two, n, m are each independently an integer of 1 to 3, R2 represents C 1～10 branched or straight chain alkyl, C 1～10 branched or straight chain alkoxy, C 1～10 Any one of branched or straight chain alkylamino groups.

[0009] Preferably, the structural formula of the benzotriazole dichroic dye of the present invention is as follows:

[0010]

[0011] Where R1 represents C 1～3 Alkyl, R2 represents C 1～10 Straight chain alkyl, C 1～10 Straight chain alkoxy, C 1～10 Any one of the straight-chain alkylamino groups.

[0012] More preferably, the benzotriazole dichroic dye of the present invention is selected from any one of compounds A to C:

[0013]

[0014]

[0015] The synthesis route and specific synthesis steps of the above-mentioned benzotriazole dichroic dye are as follows:

[0016]

[0017] Step 1: At room temperature, 3,6-dibromo-1,2-phenylenediamine was dissolved in acetic acid, and an aqueous solution of NaNO2 was added dropwise. After the addition was complete, stirring was continued for 2 hours. After stopping the reaction, the reaction solution was poured into water and filtered to prepare compound 1.

[0018] Step 2: Under nitrogen protection and room temperature, compound 1, alkyl iodide (R1I), and K2CO3 were added to DMF in a molar ratio of 1:1.5:3, and the reaction was carried out at 100°C for 3 hours. The reaction was stopped, and toluene was added to the reaction solution, followed by washing with water until neutral. The organic phase was dried over anhydrous magnesium sulfate, filtered, and spin-dried to obtain a crude product; the crude product was purified by column chromatography to prepare compound 2.

[0019] Step 3: Under nitrogen, compound 2, Ar-B(OH)2, and PdCl2(PPh3)2 were added to anhydrous toluene in a molar ratio of 1:3:0.02. The system was heated to 90°C and stirred for 6 hours before terminating the reaction. The reaction solution was washed three times with water, dried over anhydrous magnesium sulfate, filtered, and spin-dried to obtain a crude product. The crude product was purified by column chromatography to prepare compound 3.

[0020] Step 4: Compound 3 was dissolved in DMF, and NBS was added in batches under stirring at room temperature. After the addition, stirring was continued at room temperature in the dark for 6 hours, and then the reaction was stopped. The reaction solution was poured into water and filtered. The filter cake was washed three times with distilled water to prepare compound 4.

[0021] Step 5: Under nitrogen protection, compound 4, Potassium carbonate, tetrabutylammonium bromide (TBAB), and bis[(4-(N,N-dimethylamino)phenyl]di-tert-butylphosphine palladium dichloride (Pd-132) in a molar ratio of 1:3:4:0.5:0.02 were dissolved in a mixture of toluene, ethanol, and water in a volume ratio of 1:1:1. The system was heated to reflux and stirred for 8 hours before the reaction was stopped. After separation, the aqueous phase was extracted three times with toluene, and the organic phases were combined, washed three times with water, dried over anhydrous magnesium sulfate, filtered, and spin-dried to obtain a crude product. The crude product was purified by column chromatography and recrystallized from n-heptane to prepare a benzotriazole dichroic dye.

[0022] The present invention discloses a benzotriazole dichroic dye for use in preparing intelligent dimming vehicle windows. The method of use is the same as that disclosed in the invention patent application entitled "Dichroic Dye Composition" with publication number CN113166652A.

[0023] The beneficial effects of the present invention are as follows:

[0024] The benzotriazole dichroic dye of the present invention has a wide light absorption range and good stability, which makes up for the visible light absorption of thiadiazole dyes at around 400nm; the N atom can have more branched chain extension structures, which increases the solubility of the dye and enables the dye to be better dissolved in the mother liquid crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the ultraviolet absorption spectrum of compound A, B and C prepared in Examples 1 to 3 in solution.

[0026] Figure 2 This is a comparison chart of the ultraviolet absorption of compound A prepared in Example 1 and thiadiazole dyes available on the market.

[0027] Figure 3 This is the UV stability spectrum of A prepared in Example 1.

[0028] Figure 4 This is the UV stability spectrum of B prepared in Example 2.

[0029] Figure 5 This is the UV stability spectrum of C prepared in Example 3. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and examples, but the protection scope of the present invention is not limited to these examples.

[0031] Example 1

[0032]

[0033] Step 1: 3,6-dibromo-1,2-phenylenediamine (12.00 g, 44.78 mmol) and acetic acid (60 mL) were added sequentially to a 150 mL three-necked flask equipped with a mechanical stirrer and a thermometer. An aqueous solution (5 mL) of NaNO2 (4.36 g, 67.18 mmol) was added dropwise at room temperature. After the addition was complete, stirring was continued at room temperature for 2 h to stop the reaction. The reaction solution was poured into water (50 mL). A large amount of white solid precipitated from the system. After filtration, the filter cake was washed three times with distilled water to obtain 11.50 g of white solid compound 1, with a yield of 92%. The structural characterization data are as follows: 1 H NMR (500MHz, DMSO-d6) δ7.59 (s, 2H).

[0034]

[0035] Step 2: Compound 1 (7.50 g, 27.09 mmol), potassium carbonate (9.36 g, 67.71 mmol) and DMF (50 mL) were added to a 100 mL schlenk tube. After replacing nitrogen three times, iodomethane (7.70 g, 54.17 mmol) was added. The system was heated to 100 ° C. and stirred for 3 h before stopping the reaction. Toluene (50 mL) was added to the reaction solution and then washed with water (100 mL × 3 times) until neutral. The aqueous phase was extracted three times with toluene, and the organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and spin-dried to obtain a crude product. The crude product was purified by column chromatography (eluent: EA / PE = 1 / 9) to obtain 2.78 g of white solid compound 2-1, with a yield of 34%. The structural characterization data are as follows: 1HNMR(500MHz, CDCl3)δ7.44(s,2H),4.58(s,3H); 13 C NMR (126MHz, CDCl3) δ143.95, 129.71, 109.84, 43.95.

[0036]

[0037] Step 3: Under nitrogen protection, compound 2-1 (2.00 g, 6.87 mmol), 3-thiopheneboronic acid (2.64 g, 26.02 mmol), PdCl2(PPh3)2 (96 mg, 137 μmol) and anhydrous toluene (60 mL) were added in sequence to a 100 mL three-necked flask equipped with a condenser and a thermometer. The system was heated to 90 ° C. and stirred for 6 h before the reaction was stopped. The reaction solution was washed three times with water, dried over anhydrous magnesium sulfate, filtered, and dried to obtain a crude product. The crude product was purified by column chromatography (eluent: DCM / PE = 1 / 1) to obtain 1.82 g of dark yellow solid compound 3-1 with a yield of 88%. The structural characterization data are as follows: 1 H NMR (500MHz, CDCl3) δ8.06(dd,J=3.6,1.2Hz,2H),7.62(s,2H),7.39(dd,J=5.0,1.2Hz,2H),7.19(dd,J=5.1,3.6Hz,2H),4.61(s,3H); 13 C NMR (126MHz, CDCl3) δ142.42,139.85,128.11,126.92,125.64,123.53,122.99,43.64.

[0038]

[0039] Step 4: Compound 3-1 (1.70 g, 5.72 mmol) and DMF (40 mL) were added sequentially to a 150 mL three-necked flask equipped with a condenser and a thermometer. NBS (2.14 g, 12.00 mmol) was added in batches while stirring at room temperature. After the addition, stirring was continued for 6 h at room temperature in the dark, and the reaction was stopped. The reaction solution was poured into water (100 mL) to precipitate a large amount of yellow solid. After filtration, the filter cake was washed three times with distilled water to obtain 2.3 g of dark yellow solid compound 4-1, with a yield of 89%. The structural characterization data are as follows: 1 H NMR (500MHz, DMSO-d6) δ7.89 (d, J = 4.0 Hz, 2H), 7.79 (s, 2H), 7.37 (d, J = 4.0 Hz, 2H), 4.63 (s, 3H).

[0040]

[0041] Step 5: Under nitrogen protection, compound 4-1 (500 mg, 1.10 mmol), pentylphenylboronic acid (632 mg, 3.30 mmol), potassium carbonate (607 mg, 4.39 mmol), TBAB (177 mg, 550 μmol), Pd-132 (15 mg, 21 μmol), toluene (15 mL), ethanol (15 mL) and water (15 mL) were added to a 100 mL three-necked flask equipped with a condenser and a thermometer. The system was heated to reflux and stirred for 8 h before the reaction was stopped. After the system was separated, the aqueous phase was extracted three times with toluene (50 mL × 3 times), the organic phases were combined, washed three times with water, dried over anhydrous magnesium sulfate, filtered, and spin-dried to obtain a crude product. The crude product was purified by column chromatography (eluent: DCM / PE = 1 / 3) and recrystallized from n-heptane to obtain 600 mg of orange solid compound A with an HPLC purity of 99.5% and a yield of 92%. The structural characterization data are as follows: 1 H NMR (500MHz, CDCl3) δ8.04(s,2H),7.61(d,J=8.1Hz,6H),7.35(d,J=3.9Hz,2H),7.22(d,J=8.0Hz,4 H),4.63(s,3H),2.64(t,J=7.8Hz,4H),1.66(q,J=7.5Hz,4H),1.39-1.33(m,8H),0.94-0.90(m,6H); 13 CNMR(126MHz, CDCl3)δ144.60,142.70,142.34,138.70,131.75,128.98,128.0 7,125.71,123.72,123.36,122.63,43.62,35.69,31.54,31.11,22.58,14.07.

[0042] Example 2

[0043]

[0044] In step 5 of this example, the pentylphenylboronic acid in step 5 of Example 1 was replaced by an equal mole of pentyloxyphenylboronic acid. The other steps were the same as in Example 1 to obtain 300 mg of orange solid compound B with an HPLC purity of 99.7% and a yield of 55%. The structural characterization data are as follows: 1H NMR (500MHz, CDCl3) δ8.04(s,2H),7.62(d,J=5.4Hz,4H),7.28(d,J=5.6Hz,4H),6.94(t,J=7.0 Hz,4H),4.65(d,J=5.5Hz,3H),4.01(q,J=6.3Hz,4H),1.85-1.80(q,J=6.6Hz,4H),1.48-1.40(m 8H),0.96(t,J=6.6Hz,6H); 13 C NMR (201MHz, CDCl3) δ159.00,144.50,142.36,138.17,128.05,127.06,126.9 6,123.32,123.10,122.55,114.92,68.16,43.66,28.98,28.22,22.49,14.05.

[0045] Example 3

[0046]

[0047]

[0048] In step 5 of this example, pentylphenylboronic acid in step 5 of Example 1 was replaced with an equal molar amount of N,N-dibutylphenylboronic acid. The other steps were the same as in Example 1 to obtain 620 mg of red solid compound C with an HPLC purity of 99.8% and a yield of 80%. The structural characterization data are as follows: 1 H NMR (500MHz, CDCl3) δ8.03(s,2H),7.56(t,J=11.8Hz,6H),7.21(s,2H),6.67(d,J=8.3Hz,4 H),4.62(s,3H),3.32(m,8H),1.64-1.58(m,8H),1.42-1.35(m,8H),0.98(t,J=7.4Hz,12H); 13 C NMR (126MHz, CDCl3) δ147.81,145.54,142.37,136.83,128.09,126.97,123.20,122.31,121.60,111.73,50.84,43.56,29.53,20.39,14.05.

[0049] In order to demonstrate the beneficial effects of the present invention, compounds A, B, and C prepared in Example 1, Example 2, and Example 3 were dissolved in dichloromethane to prepare 1×10 -5The solution was tested for UV absorption using a UV-visible near-infrared tester (model UV-2250, produced by Shimadzu Corporation, Japan). Figure 1 The test results showed that the maximum absorption wavelengths of compounds A, B, and C were 436 nm, 442 nm, and 482 nm, respectively, and the molar absorption coefficient was 31859 ​​nm. -1 cm -1 、36769M -1 cm -1 、35415M -1 cm -1 .Depend on Figures 2 to 5 It can be seen that the benzotriazole dichroic dye of the present invention has a wide absorption range and good ultraviolet stability, which makes up for the visible light absorption of thiadiazole dyes around 400nm, and can be used to prepare smart dimming windows.

Claims

1. A benzotriazole dichroic dye, characterized in that: The structural formula of the dichroic dye is shown below: Where R1 represents C 1～8 Alkyl, Ar represents , n is an integer from 1 to 3, R2 represents C 1～10 branched or straight chain alkyl, C 1～10 branched or straight chain alkoxy, C 1～10 Any one of branched or straight chain alkylamino groups.

2. The benzotriazole dichroic dye according to claim 1, wherein The structural formula of the dichroic dye is shown below: Where R1 represents C 1～3 Alkyl, R2 represents C 1～10 Straight chain alkyl, C 1～10 Straight chain alkoxy, C 1～10 Any one of the straight-chain alkylamino groups.

3. The benzotriazole dichroic dye according to claim 2, characterized in that The dichroic dye is selected from any one of compounds A to C: 。 4. Use of the benzotriazole dichroic dye according to claim 1 in the preparation of smart dimming vehicle windows.

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