Thiophene pyrrole fused benzothiadiazole dichroic dye and application thereof

Abstract

The application discloses a thienopyrrole fused benzothiadiazole dichroic dye and application thereof. The dichroic dye takes thienopyrrole fused benzothiadiazole as an acceptor unit, a benzene ring and thienyl or its derivative as a donor unit, and a structural formula of the dichroic dye is shown in the following formula: wherein 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 branched or straight chain alkylamino, and n is an integer of 1-3. The dichroic dye has the advantages of wide ultraviolet absorption range and good ultraviolet stability, 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 particularly 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] With the continuous advancement and development of industrial technology worldwide, humanity's demand for energy is increasing. Growing energy and environmental challenges require the development of sustainable and renewable resources. Therefore, materials that can convert and conserve energy are highly desirable. Over the past few decades, numerous materials have been developed to maintain indoor temperatures. Many of these have focused on opaque structural building elements, such as walls and roofs, while other solutions have targeted transparent windows. The absorption of sunlight by building materials and the passage of visible light through transparent surfaces like windows are major causes of overheating in offices, car interiors, greenhouses, and other similar spaces. The use of artificial cooling and heating systems will only increase with the continued impact of global climate change. By around 2070, energy used for cooling systems will exceed that used for heating, and energy use for air cooling is projected to increase 40-fold by 2100. Therefore, controlling heat transfer through windows in response to changing climate conditions is a significant challenge. Currently, research on switchable glass primarily involves polymer dispersed liquid crystal (PDLC), electrochromic (EC), suspended particle optics (SPD), and dichroic dye liquid crystal (Dye LC). Among them, PDLC, SPD, and EC modes have been developed for many years. PDLC can only switch 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] 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

[0004] The present invention aims to provide a thiophene pyrrole-fused benzothiadiazole dichroic dye having strong absorption of visible light around 400 nm and 530 nm and relatively strong ultraviolet stability, as well as 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 branched or straight chain alkylamino groups, wherein n is an integer of 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, thiopheneboric acid, potassium carbonate, tetrabutylammonium bromide (TBAB), and bis[(4-(N,N-dimethylamino)phenyl]di-tert-butylphosphine palladium dichloride (Pd-132) were dissolved in a molar ratio of 1:3:4:0.1:0.02 in a mixture of toluene, ethanol, and water in a volume ratio of 1:1:1. The system was heated to reflux and stirred under reflux for 8 hours before stopping the reaction. 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 stirring at reflux for 7 hours. The organic phase was dried over anhydrous magnesium sulfate, filtered, and 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 mixture was stirred at room temperature in the dark for 6 h before stopping the reaction. 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), and 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 mixture of toluene, ethanol, and water in a volume ratio of 1:1:1. The system was heated to reflux and stirred under reflux for 8 hours before the reaction was stopped. 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 a thiophenepyrrole-fused benzothiadiazole dichroic dye.

[0021] The present invention also provides the use of the thiophene pyrrole-fused benzothiadiazole dichroic dye in the preparation of smart car windows. The method of use is the same as that disclosed in the invention patent application entitled "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 extended 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 ultraviolet absorption spectrum of compound A, B and C prepared in Examples 1 to 3 in solution.

[0025] Figure 2 The UV absorption spectra of compound C prepared in Example 3 and the reference compound in solution are shown in FIG. DETAILED DESCRIPTION

[0026] 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.

[0027] Example 1

[0028]

[0029] Step 1: Under nitrogen, 4,7-dibromo-5-nitrobenz[c][1,2,5]thiadiazole (5.00 g, 14.75 mmol), thiopheneboronic 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 sequentially to a 150 mL three-necked flask equipped with a mechanical stirrer and a thermometer. The system was heated to reflux and stirred at reflux for 8 h before the reaction was stopped. After separation, the aqueous phase was extracted with toluene (50 mL x 3). The organic phases were combined, washed three times with water, dried over anhydrous magnesium sulfate, filtered, and spin-dried to obtain the crude product. 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 sequentially to a 150 mL three-necked flask equipped with a mechanical stirrer and a thermometer. The system was heated to reflux and stirred under reflux for 7 h before the reaction was stopped. 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 stirred at room temperature for 12 h before stopping the reaction. The reaction solution was poured into water (100 mL) and extracted with toluene (150 mL × 3). 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 sequentially to a 100 mL single-necked flask. NBS (228 mg, 1.28 mmol) was added in batches while stirring at room temperature. After the addition, the mixture was stirred in the dark for 6 h at room temperature to stop the reaction. The reaction solution was poured into water (100 mL). A large amount of orange solid precipitated and was 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 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 1500 mg of red solid compound A with an HPLC purity of 99.6% and a yield of 55%. The structural characterization data are as follows: 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 an HPLC purity of 99.3% and a yield of 55%. The structural characterization data are 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. The other steps were the same as in Example 1 to obtain 300 mg of red solid compound C with an 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 showed that the maximum absorption wavelengths of compounds A, B, and C were 370nm and 493nm, 368nm and 494nm, 389nm and 530nm, respectively, and the molar absorption coefficient was 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 the thiadiazole dye 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 1～3 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.

2. The thiophenepyrrole-fused benzothiadiazole dichroic dye according to claim 1, characterized in that: The dichroic dye is selected from any one of compounds A to C: 。 3. Use of the thiophene pyrrole-fused benzothiadiazole dichroic dye according to claim 1 in the preparation of smart car windows.

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