Thiophene pyrrole fused benzothiadiazole dichroic dye and application thereof

Abstract

The invention discloses a thiophene pyrrole fused benzothiadiazole dichroic dye and application thereof.The thiophene pyrrole fused benzothiadiazole dichroic dye takes thiophene pyrrole fused benzothiadiazole as an acceptor unit and a benzene ring and thiophene or a derivative thereof as a donor unit, and the structural formula of the dichroic dye is # imgabs0 #, r2 represents any one of C3-10 branched chain or straight chain alkyl, C3-10 branched chain or straight chain alkoxy and C3-10 branched chain or straight chain alkylamino, and n is an integer of 1-3. The dichroic dye disclosed by the invention has the advantages of wide ultraviolet absorption range, good ultraviolet stability and the like, and can be used for preparing high-performance intelligent vehicle windows.

Description

Technical Field

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

[0002] As industrial technology continues to advance and develop worldwide, human demand for energy is increasing. The growing energy and environmental challenges require the development of sustainable and renewable resources. Therefore, materials that can convert and save energy are highly desirable. In the past few decades, many materials have been developed to maintain indoor temperature. Many of them focus on opaque structural building elements such as walls and roofs, and other solutions target transparent windows. The absorption of sunlight by building materials and the passage of visible light through transparent surfaces such as windows are the main causes of overheating inside offices, car interiors, greenhouses and other similar spaces. The use of artificial refrigeration and heating systems will only increase with the continued impact of global climate change. By around 2070, the energy used for cooling systems will exceed the energy used for heating. It is expected that by 2100, the use of air cooling energy will increase 40 times. Therefore, in order to cope with changing climate conditions, controlling the passage of heat through windows is a huge challenge. The dimming glass currently being studied mainly includes polymer dispersed liquid crystal (PDLC), electrochromic (EC) and suspended particles (SPD) and dichroic dye liquid crystal (Dye LC) and other types. Among them, PDLC, SPD, and EC modes have been developed for many years. PDLC can only achieve switching between transparency and haze, and does not block light or insulate heat. EC has problems such as complex film process, slow response time, and blue and distorted dark state color.

[0003] So far, the most widely studied dichroic dyes are azo, anthraquinone, and so on. The linear structure of azo dyes can be well matched with the structure of the main liquid crystal (generally a rod-shaped structure). The monoazo was synthesized in the early stage, and later it was found that the designed and synthesized disazo and triazo have higher order parameters. By introducing heterocyclic rings, better photoelectric properties, thermodynamic properties and solubility can be obtained, but the disadvantage is that they are optically unstable. Anthraquinone dyes have higher light resistance and stability than azo dyes. Although the color of anthraquinone dyes is weaker than that of azo dyes, the color range can be increased by introducing different substituents on the matrix; the disadvantage is that the structure is too large, which is too different from the common rod-shaped liquid crystal molecular structure, so that it cannot be well dissolved in the main liquid crystal, resulting in a low order parameter. Although there are many dichroic dye liquid crystal color-adjustable smart windows on the market, the existing color-changing smart windows are not smart enough, because most color-changing materials are difficult to achieve zero transmission over the entire visible spectrum (380-780nm), resulting in light always passing through the window. Summary of the invention

[0004] The purpose of the present invention is to provide a thiophene pyrrole-fused benzothiadiazole dichroic dye which has strong absorption of visible light around 400nm and 530nm and strong ultraviolet stability, and the use of the dichroic dye.

[0005] For the above purpose, the structural formula of the thiophene pyrrole-fused benzothiadiazole dichroic dye provided by the present invention is as follows:

[0006]

[0007] Where R1 represents C 1～8 Alkyl, R2 represents C 3～10 branched or straight chain alkyl, C 3～10 Branched or straight chain alkoxy, C 3～10 Any one of a branched or straight chain alkylamino group, wherein n is an integer from 1 to 3.

[0008] Preferably, the structural formula of the thiophene pyrrole-fused benzothiadiazole dichroic dye of the present invention is as follows:

[0009]

[0010] Where R1 represents C 1～3 Alkyl, R2 represents C 3～10 Straight chain alkyl, C 3～10 Straight chain alkoxy, C 3～10 Any one of the straight-chain alkylamino groups.

[0011] More preferably, the thiophene pyrrole-fused benzothiadiazole dichroic dye of the present invention is selected from any one of compounds A to C:

[0012]

[0013]

[0014] The synthesis route and specific synthesis steps of the above-mentioned thiophene pyrrole-fused benzothiadiazole dichroic dye are as follows:

[0015]

[0016] Step 1: Under nitrogen protection, 4,7-dibromo-5-nitrobenz[c][1,2,5]thiadiazole, thiophene boronic acid, potassium carbonate, tetrabutylammonium bromide (TBAB), bis[(4-(N,N-dimethylamino)phenyl]di-tert-butylphosphine palladium dichloride (Pd-132) in a molar ratio of 1:3:4:0.1:0.02 were dissolved in a mixed solution of toluene, ethanol, and water in a volume ratio of 1:1:1. The system was heated to reflux, and the reaction was stopped after stirring at reflux for 8 hours. After separation, the aqueous phase was extracted three times with toluene, 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 obtain compound 1.

[0017] Step 2: Under nitrogen protection, compound 1 and triphenylphosphine (TPP) were added to o-dichlorobenzene (o-DCB) in a molar ratio of 1:8, the system was heated to reflux, and the reaction was stopped after reflux stirring for 7 hours. 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 and recrystallized from ethanol to obtain compound 2.

[0018] Step 3: Compound 2, alkyl iodide (R1I) and K2CO3 were added to DMF in a molar ratio of 1:2:3 and stirred at room temperature for 12 hours. After the reaction, toluene was added to the reaction solution and washed 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 recrystallized from ethanol to obtain compound 3.

[0019] Step 4: Compound 3 was dissolved in DMF, and N-bromosuccinimide (NBS) was added in batches under stirring at room temperature. After the addition, the reaction was stopped after stirring for 6 h at room temperature in the dark. The reaction solution was poured into water and filtered. The filter cake was washed three times with distilled water to obtain compound 4.

[0020] Step 5: Under nitrogen protection, compound 4, Potassium carbonate, tetrabutylammonium bromide (TBAB), bis[(4-(N,N-dimethylamino)phenyl]di-tert-butylphosphine palladium dichloride (Pd-132) in a molar ratio of 1:3:4:0.1:0.02 are dissolved in a mixed solution of toluene, ethanol and water in a volume ratio of 1:1:1. The system is heated to reflux, and the reaction is stopped after reflux stirring for 8 hours. After separation, the aqueous phase is extracted three times with toluene, the organic phases are combined, washed three times with water, dried over anhydrous magnesium sulfate, filtered, and spin-dried to obtain a crude product. The crude product is purified by column chromatography and recrystallized from n-heptane to obtain a thiophene pyrrole-fused benzothiadiazole dichroic dye.

[0021] The present invention also provides the use of the thiophene pyrrole-fused benzothiadiazole dichroic dye in preparing smart car windows. The use method is the same as the method disclosed in the invention patent application with the invention name "Dichroic Dye Composition" and publication number CN113166652A.

[0022] The beneficial effects of the present invention are as follows:

[0023] The thiophene pyrrole-fused benzothiadiazole dichroic dye of the present invention has a wide ultraviolet absorption range and good ultraviolet stability, which makes up for the poor solubility of thiadiazole dyes; 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

[0024] Figure 1 It is the UV absorption spectrum of compounds A, B and C prepared in Examples 1 to 3 in solution.

[0025] Figure 2 It is the UV absorption spectrum of compound C prepared in Example 3 and the reference compound in solution. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0027] Example 1

[0028]

[0029] Step 1: Under nitrogen protection, 4,7-dibromo-5-nitrobenz[c][1,2,5]thiadiazole (5.00 g, 14.75 mmol), thiopheneboric acid (5.66 g, 44.25 mmol), potassium carbonate (8.15 g, 59.00 mmol), tetrabutylammonium bromide (475 mg, 1.48 mmol), Pd(amphos)Cl2 (208 mg, 295 μmol), toluene (20 mL), ethanol (20 mL) and water (20 mL) were added to a 150 mL three-necked flask equipped with a mechanical stirrer and a thermometer. The system was heated to reflux and the reaction was stopped after stirring at reflux for 8 h. After the system was separated, the aqueous phase was extracted with toluene (50 mL × 3), the organic phases were combined, washed three times with water, dried over anhydrous magnesium sulfate, filtered, and the crude product was obtained after spin drying. The crude product was purified by column chromatography (eluent: DCM / PE=1 / 1) and recrystallized from n-heptane to obtain 4.00 g of red solid compound 1 with a yield of 80%. The structural characterization data are as follows: 1 H NMR (800MHz, CDCl3) δ8.17(d,J=4.8Hz,1H),8.09(s,1H),7.65(d,J=6.3Hz,1H),7.57(d,J= 6.2Hz,1H),7.43(d,J=3.7Hz,1H),7.25(dd,J=5.1,3.7Hz,1H),7.21(dd,J=5.1,3.6Hz,1H); 13C NMR (201MHz, CDCl3) δ154.11,151.98,148.92,137.23,131.39,130.00,129.67,129.31,129.02,128.39,127.80,127.61,119.56,119.32.

[0030]

[0031] Step 2: Under nitrogen protection, compound 1 (3.80 g, 11.00 mmol), triphenylphosphine (23.08 g, 88.01 mmol) and o-dichlorobenzene (70 mL) were added in sequence to a 150 mL three-necked flask equipped with a mechanical stirrer and a thermometer. The system was heated to reflux, and the reaction was stopped after reflux stirring for 7 h. 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 (eluent: EA / PE = 1 / 3) and recrystallized from ethanol to obtain 2.50 g of red solid compound 2, with a yield of 73%. The structural characterization data are as follows: 1 H NMR (800MHz, DMSO-d6) δ12.13(s,1H),8.16(s,1H),8.11(dd,J=3.7,1.2Hz,1H),7.58(d,J=5. 1Hz,1H),7.52(dd,J=5.1,1.1Hz,1H),7.28(d,J=5.1Hz,1H),7.21(dd,J=5.1,3.6Hz,1H); 13 C NMR (201MHz, DMSO-d6) δ149.80,149.34,143.62,140.24,139.26,128.56,128.08,126.73,126.09,120.82,118.47,116.22,112.46,109.67.

[0032]

[0033] Step 3: Compound 2 (2.50 g, 7.98 mmol), iodomethane (2.26 g, 15.95 mmol), potassium carbonate (3.31 g, 23.93 mmol), and DMF (60 mL) were added to a 100 mL single-necked flask in sequence, and the reaction was stopped after stirring at room temperature for 12 h. The reaction solution was poured into water (100 mL), and toluene (150 mL × 3) was added for extraction. The organic phase was dried over anhydrous magnesium sulfate, filtered, and dried to obtain a crude product. The crude product was recrystallized from ethanol to obtain 2.00 g of yellow solid compound 3-1, with a yield of 74%. The structural characterization data are as follows: 1HNMR(500MHz,CDCl3)δ8.07(d,J=4.8Hz,1H),7.80(dd,J=14.7,6.4Hz,1H),7.46(d ,J=16.1Hz,2H),7.24(d,J=21.3Hz,1H),7.07(d,J=4.6Hz,1H),4.04–3.91(m,3H); 13 C NMR (126MHz, CDCl3) δ149.78,149.25,145.17,140.43,139.06,128.20,127.90,126.80,125.51,121.28,117.83,112.84,109.96,32.03.

[0034]

[0035] Step 4: Compound 3-1 (200 mg, 610 μmol) and DMF (40 mL) were added to a 100 mL single-necked flask in sequence, and NBS (228 mg, 1.28 mmol) was added in batches under stirring at room temperature. After the addition, the mixture was stirred at room temperature in the dark for 6 h to stop the reaction. The reaction solution was poured into water (100 mL), and a large amount of orange solid was precipitated and filtered. The filter cake was washed three times with distilled water to obtain 2.40 g of orange solid compound 4-1, with a yield of 82%. The structural characterization data are as follows: 1 H NMR (500MHz, THF-d8) δ8.11(s,1H),7.86(d,J=4.0Hz,1H),7.45(s,1H),7.18(d,J=4.0Hz,1H),4.05(s,3H); 13 C NMR(126MHz,THF-d8)δ149.46,148.72,143.54,141.86,138.31,130.26, 126.01,120.32,117.36,114.47,114.32,112.85,112.43,109.64,33.48.

[0036]

[0037] Step 5: Under nitrogen protection, compound 4-1 (200 mg, 412 μmol), pentylphenylboronic acid (237 mg, 1.24 mmol), potassium carbonate (227 mg, 1.65 mmol), tetrabutylammonium bromide (13 mg, 41 μmol), Pd-132 (5 mg, 8 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 the reaction was stopped after stirring at reflux for 8 h. After the system was separated, the aqueous phase was extracted three times with toluene (50 mL × 3 times), the organic phase was 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 1500 mg of red solid compound A, HPLC purity 99.6%, yield 55%, and structural characterization data: 1 H NMR (800MHz, CDCl3) δ7.99(d,J=3.6Hz,1H),7.64(s,1H),7.60(d,J=7.9Hz,2H),7.56(d,J=7.7Hz,2H),7.31(d,J=3.7Hz,1H),7.21(dd,J =12.7,7.7Hz,4H),7.11(s,1H),3.86(s,3H),2.66–2.61(m,4H),1.67(q,J=7.5,6.8Hz,4H),1.42–1.33(m,8H),0.93(t,J=6.7Hz,6H); 13 C NMR (201MHz, CDCl3) δ149.73,149.10,147.10,145.40,144.09,142.89,142.58,139.23,138.54,132.54,131.75,129.05,128.95,127.74,125 .60,125.45,123.40,120.78,116.67,111.75,109.91,105.15,35.71,3 5.69,31.86,31.58,31.14,31.08,22.60,14.10; HRMS(ESI,m / z):[M+H] + (C 37 H 38 N3S3):Theoretical value 620.2222, measured value 620.2219.

[0038] Example 2

[0039]

[0040] In step 5 of this example, pentyloxyphenylboronic acid was used to replace the pentylphenylboronic acid in step 5 of example 1. The other steps were the same as in example 1 to obtain 140 mg of red solid compound B with HPLC purity of 99.3% and yield of 55%. The structural characterization data were as follows: 1 H NMR (800MHz, CDCl3) δ8.09(d,J=3.7Hz,1H),7.91(s,1H),7.64(dd,J=10.5,8.6Hz,4H),7.31(d,J=3.7Hz,1H),6.95(dd,J=14.4,8.5Hz,4H),4.08(s ,3H),4.01(q,J=6.5Hz,4H),1.82(td,J=9.4,4.8Hz,4H),1.47(q,J=7.7Hz ,4H),1.41(q,J=7.4Hz,4H),0.95(t,J=7.3Hz,6H); HRMS(ESI,m / z):[M+H] + (C 37 H 38 N3O2S3): Theoretical value 652.2121, measured value 652.2125.

[0041] Example 3

[0042]

[0043] 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, and the other steps were the same as in example 1 to obtain 300 mg of red solid compound C with HPLC purity of 99.7% and a yield of 67%. The structural characterization data are as follows: 1 H NMR (800MHz, CDCl3) δ8.08(s,1H),7.83(s,1H),7.56(d,J=4.2Hz,4H),7.22(s,1H),7.13(s,1H),6.67(d,J=8.4Hz,4H),4.02(s ,3H),3.32(s,8H),1.64–1.59(m,8H),1.39(ddt,J=10.8,7.5,3.4Hz,8H),0.98(td,J=7.4,3.4Hz,12H); HRMS(ESI,m / z):[M+H] + (C 43 H 52 N5S3): Theoretical value 734.3379, measured value 734.3387.

[0044] 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 1×10-5 The obtained solutions were tested for UV absorption using a UV-visible near-infrared tester (model UV-2250, produced by Shimadzu Corporation, Japan). Figure 1 The test results show that the maximum absorption wavelengths of compounds A, B, and C are 370nm and 493nm, 368nm and 494nm, 389nm and 530nm, respectively, and the molar absorption coefficient is 43233M -1 cm -1 and 24276M -1 cm -1 、48469M -1 cm -1 and 26041M -1 cm -1 、54460M -1 cm -1 and 31385M -1 cm -1 .Depend on Figure 2 It can be seen that compound C and the control compound (structural formula as Figure 2 The results show that the ultraviolet absorption range of the thiophene pyrrole-fused benzothiadiazole dichroic dye of the present invention is wider, which makes up for the visible light absorption of thiadiazole dyes at around 400nm and 530nm.

Claims

1. A thiophene pyrrole-fused benzothiadiazole dichroic dye, characterized in that: The structural formula of the dichroic dye is shown below: Where R1 represents C 1～8 Alkyl, R2 represents C 3～10 branched or straight chain alkyl, C 3～10 Branched or straight chain alkoxy, C 3～10 Any one of a branched or straight chain alkylamino group, wherein n is an integer from 1 to 3.

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

3. The thiophene pyrrole-fused benzothiadiazole 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 thiophene pyrrole-fused benzothiadiazole dichroic dye according to claim 1 in the preparation of smart car windows.

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