A quinoxaline derivative, a preparation method thereof, and an electrochromic material prepared from the derivative and a preparation method thereof

Abstract

The present application relates to the technical field of electrochromic materials, and particularly relates to a quinoxaline derivative, a preparation method of the quinoxaline derivative, an electrochromic material prepared from the quinoxaline derivative and a preparation method of the electrochromic material. The quinoxaline derivative is prepared from quinoxaline as a central acceptor and 3,4-(2,2-dimethylpropylene dioxy) thiophene as a donor through Stille coupling, and then the quinoxaline derivative can be made into a thin film through cyclic voltammetry. The thin film is a high-performance blue-transparent electrochromic material, presents blue in a neutral state, can realize color change under a voltage of -0.3-0.7 V, has an optical contrast of 38.25% in a wavelength range of 610 nm, has a coloring time of 1.47 s, has a bleaching time of 0.54 s, and has no obvious attenuation in contrast after 600 cycles.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochromic materials, and particularly relates to a quinoxaline derivative, a preparation method thereof, and an electrochromic material prepared from the derivative and a preparation method thereof. BACKGROUND

[0002] Electrochromism (EC) refers to a reversible change in the optical properties of a material under the action of an electric field or voltage. Materials with electrochromism are called electrochromic materials, and the reversible switching of color is the most intuitive external manifestation of electrochromic materials.

[0003] Organic conductive polymers have the advantage of adjustable energy gap, and those skilled in the art can obtain different colors by adjusting the energy gap. RGB three primary colors can be synthesized in different proportions to produce almost all colors that can be perceived by human vision, and is one of the most widely used color systems. However, the display technology also requires the material to be able to switch between primary color-transparent. However, there are still few electrochromic films that can switch between blue-transparent. SUMMARY

[0004] The present application relates to the technical field of electrochromic materials, and particularly relates to a quinoxaline derivative, a preparation method thereof, and an electrochromic material prepared from the derivative and a preparation method thereof.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] A quinoxaline derivative, which is 5,8-bis(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxin-6-yl)-2,3-dimethyl-4a,8a-dihydroquinoxaline, and its structure is shown as formula (I):

[0007]

[0008] The present application provides a preparation method of the quinoxaline derivative, comprising the following steps:

[0009] Step 1): 3,6-dibromobenzene-1,2-diamine, 1,4-butanedione and a solvent are mixed and reacted under a protective atmosphere to generate 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline;

[0010] Step 2): 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline prepared in step 1) is mixed with tributyl(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxin-6-yl)stannane, a solvent and a catalyst, and then reacted to generate the quinoxaline derivative shown in formula (I).

[0011] Optionally, the molar ratio of the 3,6-dibromobenzene-1,2-diamine and 1,4-butanedione in step 1) is 1:2.5-3.5; the solvent comprises acetic acid, and the ratio of the solvent to 3,6-dibromobenzene-1,2-diamine is 15-25 mL:1 g.

[0012] Optionally, the reaction in step 1) is specifically refluxing 3,6-dibromobenzene-1,2-diamine, 1,4-butanedione, and the solvent at 100-140 ℃ for 15-24 h to obtain the target product 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline.

[0013] Optionally, the molar ratio of the 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline to tributyl(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxin-6-yl)stannane in step 2) is 1:2.5-4;

[0014] The catalyst comprises at least one of tetrakis(triphenylphosphine)palladium and palladium acetate;

[0015] The solvent comprises N,N-dimethylformamide;

[0016] The ratio of the solvent to 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline is 55-70 mL:1 g;

[0017] The molar ratio of the catalyst to 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline is 0.04-0.06:1.

[0018] Optionally, the reaction in step 2) is specifically refluxing 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline, tributyl(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxin-6-yl)stannane, the catalyst, and the solvent at 140-175 ℃ for 12-24 h under a protective atmosphere to obtain the quinoxaline derivative shown in formula (I).

[0019] The application further provides a blue-transparent electrochromic material prepared using the quinoxaline derivative shown in formula (I).

[0020] The application further provides a preparation method of the blue-transparent electrochromic material, comprising the following steps:

[0021] The quinoxaline derivative shown in formula (I) is dissolved in a mixed solvent of dichloromethane and acetonitrile containing tetrabutylammonium hexafluorophosphate to obtain a mixed solution, and the blue-transparent electrochromic material can be prepared by electrochemical polymerization of the mixed solution.

[0022] Optionally, the concentration of tetrabutylammonium hexafluorophosphate in the mixed solvent is 0.09-0.12 mol / L; the volume ratio of dichloromethane and acetonitrile is 8:1-4; and the concentration of the quinoxaline derivative of formula (I) in the mixed solution is 0.5-1.5 mmol / L.

[0023] Optionally, the polymerization voltage of the electrochemical polymerization is -0.5-1.5 V, and the scanning speed is 80-120 mV / s.

[0024] The synthetic route of the quinoxaline derivative is as follows:

[0025]

[0026] The 3,6-dibromobenzene-1,2-diamine (formula III) used in the application can be prepared by reacting 4,7-dibromobenzothiazole (formula II) with sodium borohydride, or can be directly purchased.

[0027] The 3,6-dibromobenzene-1,2-diamine is reacted with 1,4-butanedione to prepare 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline (formula IV), and the 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline is reacted with tributyl(3,3-dimethyl-3,4-dihydro-2H-thiopheno[3,4-b][1,4]dioxane-6-yl)stannane (formula V) to obtain the quinoxaline derivative of formula (I).

[0028] The D-A structure design concept (donor-acceptor structure) is used in the design and preparation of quinoxaline derivatives shown in formula (I), the "donor-acceptor" material obtained by the design concept has excellent stability, and is widely used in the fields of organic photoelectricity, thermoelectricity, photo-thermal conversion and fluorescent biological imaging. Quinoxaline is widely used in the field of electrochromism as a common acceptor structure, and researchers have made a series of work around it, and the relationship between electrochromic polymers and structures is related. Since the electrochromic material for display must contain a transparent state, the introduction of 3,4-ethylenedioxythiophene (EDOT) as the D structure is necessary. In view of the above consideration, the quinoxaline is selected as the central acceptor, and the 3,4-(2,2-dimethylpropylenedioxy) thiophene is selected as the donor unit, and the quinoxaline derivative monomer shown in formula (I) is finally prepared by Stille coupling, and the quinoxaline derivative is polymerized into an electrochromic material by cyclic voltammetry. If the voltage is too low during the polymerization process, the monomer cannot be electro-polymerized, and if the voltage is too high, the generated polymer will be damaged due to overvoltage; the lower the scanning speed during the polymerization process, the more uniform the surface of the material prepared by electro-polymerization, and the higher the scanning speed, the rougher the surface of the material. The prepared electrochromic material is a blue-transparent electrochromic film, which presents blue in the neutral state, and can realize color change under the voltage of-0.3-0.7V, the optical contrast in the wavelength range of 610nm is 38.25%, the coloring time is 1.47s, and the bleaching time is 0.54s; after 600 cycles, the contrast does not obviously attenuate, and it is a blue-transparent new high-performance electrochromic material with great potential. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The cyclic voltammetry polymerization curve of the quinoxaline derivative prepared in Example 1 is shown in the figure;

[0030] Figure 2 The ultraviolet-visible absorption spectrum of the quinoxaline derivative polymer film prepared in Example 1 under different voltages is shown in the figure;

[0031] Figure 3 The response time graph of the quinoxaline derivative polymer film prepared in Example 1 under the wavelength of 610nm is shown in the figure;

[0032] Figure 4 The kinetic test graph of the quinoxaline derivative polymer film prepared in Example 1 under the wavelength of 610nm is shown in the figure. DETAILED DESCRIPTION

[0033] The application provides a quinoxaline derivative, which is 5,8-bis(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxane-6-yl)-2,3-dimethyl-4a,8a-dihydroquinoxaline, and the structure is shown in formula (I).

[0034]

[0035] The present application provides a preparation method of the quinoxaline derivative, comprising the following steps:

[0036] Step 1): reacting 3,6-dibromobenzene-1,2-diamine, 1,4-butanedione and a solvent to generate 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline under a protective atmosphere;

[0037] Step 2): reacting 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline prepared in step 1) with tributyl(3,3-dimethyl-3,4-dihydro-2H-thiopheno[3,4-b][1,4]dioxin-6-yl)stannane, a solvent and a catalyst to generate the quinoxaline derivative of formula (I).

[0038] In the present application, 3,6-dibromobenzene-1,2-diamine in step (1) can be purchased or prepared, and the present application provides a preparation method of 3,6-dibromobenzene-1,2-diamine, comprising the following steps:

[0039] reacting 4,7-dibromobenzothiazole, sodium borohydride and ethanol to generate the 3,6-dibromobenzene-1,2-diamine.

[0040] In the present application, the molar ratio of 4,7-dibromobenzothiazole to sodium borohydride is preferably 1:15-20, further preferably 1:17-19.5, and more preferably 1:18-19.

[0041] In the present application, the mass-volume ratio of 4,7-dibromobenzothiazole to ethanol is preferably 1g:30-40mL, further preferably 1g:32-38mL, and more preferably 1g:34-36mL.

[0042] In the present application, 4,7-dibromobenzothiazole and ethanol are preliminarily mixed, the temperature of the preliminary mixing is preferably 0 to -5℃, further preferably -1 to -4℃, more preferably -2 to -3℃; then sodium borohydride is added in batches, the number of batches is preferably ≥3 times, further preferably ≥4 times, more preferably ≥5 times; after the addition of sodium borohydride, the temperature is kept unchanged for stirring, the stirring rate is 300 to 1500 r / min, preferably 500 to 1300 r / min, further preferably 600 to 1200 r / min, more further preferably 800 to 1000 r / min; the stirring time is preferably 20 to 40 min, further preferably 25 to 35 min, more preferably 26 to 34 min. After the stirring is completed, the temperature is naturally increased; the target temperature of the temperature increase is preferably 20 to 30℃, further preferably 22 to 28℃, more preferably 24 to 26℃. Then the reaction is carried out at the current temperature.

[0043] In the present application, the stirring rate of the reaction is preferably 300 to 1500 r / min, preferably 500 to 1300 r / min, further preferably 600 to 1200 r / min, more further preferably 800 to 1000 r / min; the reaction time is preferably 12 to 14 h, further preferably 12.5 to 13.5 h, more preferably 12.8 to 13.2 h.

[0044] In the present application, after the reaction is completed, the reaction solvent is removed, deionized water is added to quench the reaction; then the reaction mixture is extracted with ethyl acetate, the obtained organic phase is washed with saturated brine, the number of washing is preferably ≥3 times, further preferably ≥4 times, more preferably ≥5 times; after the washing, the organic layers are combined and dried with anhydrous sodium sulfate; after the drying, silica gel is added for stirring, the mesh number of the silica gel is 200 to 300 meshes; the amount of the silica gel is preferably 3 to 8 times, further preferably 4 to 7 times, more further preferably 5 to 6 times of the mass of all the reactants. Then elution is carried out, the eluent of the elution contains dichloromethane and petroleum ether, the volume ratio of the dichloromethane and the petroleum ether is preferably 1:2 to 4, further preferably 1:2.2 to 3.8, more preferably 1:2.5 to 3.5; then chromatography is carried out on a column with silica gel as the stationary phase, the mesh number of the silica gel is preferably 300 to 400 meshes; finally, the white solid obtained is 3,6-dibromobenzene-1,2-diamine.

[0045] In the present application, the protective atmosphere in step 1) contains at least one of nitrogen, helium, neon, argon, krypton, xenon, and radon.

[0046] In the present application, the molar ratio of 3,6-dibromobenzene-1,2-diamine and 1,4-butanedione in step 1) is 1:2.5-3.5, preferably 1:2.6-3.3, further preferably 1:2.8-3.1, and more preferably 1:2.9-3; the solvent comprises acetic acid, and the volume ratio of the solvent to 3,6-dibromobenzene-1,2-diamine is 15-25 mL:1 g, preferably 17-24 mL:1 g, further preferably 18-22 mL:1 g, and more preferably 19-21 mL:1 g.

[0047] In the present application, the reaction in step 1) is carried out at 100-140°C, preferably 105-135°C, further preferably 110-130°C, and more preferably 115-125°C, after mixing 3,6-dibromobenzene-1,2-diamine, 1,4-butanedione, and the solvent, and refluxing for 15-24 h, preferably 16-23 h, further preferably 17-22 h, and more preferably 19-21 h.

[0048] In the present application, after the reaction in step 1) is completed, post-treatment is carried out. The reaction mixture is extracted with dichloromethane, and the obtained organic phase is washed with saturated brine, and the washing is preferably performed ≥3 times, further preferably ≥4 times, and more preferably ≥5 times; after washing, the organic layers are combined and dried with anhydrous sodium sulfate; after drying, silica gel is added and stirred, and the mesh number of the silica gel is 200-300 mesh; the amount of the silica gel is preferably 3-8 times, further preferably 4-7 times, and more preferably 5-6 times the mass of all the reactants. Then, column chromatography is carried out, and the eluent of the column chromatography comprises dichloromethane and petroleum ether, and the volume ratio of dichloromethane to petroleum ether is preferably 1:2-4, further preferably 1:2.2-3.8, and more preferably 1:2.5-3.5; the stationary phase of the column chromatography is silica gel, and the mesh number of the silica gel is 300-400 mesh; and finally, white solid is obtained, which is 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline.

[0049] In the present application, the structure of 3,6-dibromobenzene-1,2-diamine is as follows:

[0050]

[0051] In the present application, the structure of 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline is as follows:

[0052]

[0053] In the present application, the molar ratio of 5,8-dibromo-2,3-dimethyl-4a,8a- dihydroquinoxaline to tributyl(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][l,4]dioxan-6- yl)stannane in step 2) is 1:2.5-4, preferably 1:2.7-3.8, further preferably 1:2.9-3.6, more further preferably 1:3.1-3.4;

[0054] The catalyst comprises at least one of tetrakis(triphenylphosphine)palladium, palladium acetate;

[0055] The solvent comprises N,N-dimethylformamide;

[0056] The solvent and 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline are used in a ratio of 55-70 mL: 1 g, preferably 58-68 mL: 1 g, further preferably 60-66 mL: 1 g, more further preferably 62-65 mL: 1 g;

[0057] The molar ratio of the catalyst to 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline is 0.04-0.06: 1, preferably 0.042-0.057: 1, further preferably 0.044-0.055: 1, more further preferably 0.048-0.052: 1.

[0058] In the present application, the reaction in step 2) is specifically refluxing 5,8-dibromo- 2,3-dimethyl-4a,8a-dihydroquinoxaline, tributyl(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4- b][l,4]dioxan-6-yl)stannane, catalyst and solvent after mixing under a protective atmosphere at 140-175°C, preferably 145-170°C, further preferably 150-165°C, more further preferably 155-160°C for 12-24 h, preferably 14-22 h, further preferably 15-20 h, more further preferably 16-18 h; to obtain the quinoxaline derivative shown in formula (I).

[0059] In the present application, the protective atmosphere in step 2) comprises at least one of nitrogen, helium, neon, argon, krypton, xenon, radon.

[0060] In the present application, the structure of tributyl(3,3-dimethyl-3,4-dihydro-2H- thieno[3,4-b][l,4]dioxan-6-yl)stannane is as shown below:

[0061]

[0062] In the present application, after the reaction of step 2) is completed, post-treatment is performed. The reaction mixture is extracted with dichloromethane, and the obtained organic phase is washed with saturated brine, the number of washing is preferably ≥ 3 times, further preferably ≥ 4 times, more preferably ≥ 5 times; after washing, the organic layers are combined and dried with anhydrous sodium sulfate; after drying, silica gel is added and stirred, the mesh number of the silica gel is 200-300 mesh; the amount of the silica gel is preferably 3-8 times, further preferably 4-7 times, more preferably 5-6 times of the mass of all the reactants. Then, column chromatography is performed, the eluent of the column chromatography comprises dichloromethane and petroleum ether, the volume ratio of the dichloromethane and the petroleum ether is preferably 1:2-4, further preferably 1:2.2-3.8, more preferably 1:2.5-3.5; the stationary phase of the column chromatography is silica gel, the mesh number of the silica gel is 300-400 mesh, and finally a yellow solid, i.e. the quinoxaline derivative, is obtained.

[0063] The present application also provides a blue-transparent electrochromic material prepared from the quinoxaline derivative.

[0064] The present application also provides a preparation method of the blue-transparent electrochromic material, comprising the following steps:

[0065] The quinoxaline derivative shown in formula (I) is dissolved in a mixed solvent of dichloromethane and acetonitrile containing tetrabutylammonium hexafluorophosphate to obtain a mixed solution, and the blue-transparent electrochromic material can be prepared by electrochemical polymerization of the mixed solution.

[0066] In the present application, tetrabutylammonium hexafluorophosphate is dissolved in a mixed solvent of dichloromethane and acetonitrile, and then quinoxaline derivative is added.

[0067] In the present application, the concentration of tetrabutylammonium hexafluorophosphate in the mixed solvent is 0.09-0.12 mol / L, preferably 0.10-0.11 mol / L; the volume ratio of dichloromethane and acetonitrile is 8:1-4, preferably 8:1.2-3.5, further preferably 8:1.5-3, more preferably 8:2-2.5; the concentration of quinoxaline derivative shown in formula (I) in the mixed solution is 0.5-1.5 mmol / L, preferably 0.7-1.2 mmol / L, further preferably 0.8-1.1 mmol / L, more preferably 1 mmol / L.

[0068] In the present application, the polymerization voltage of the electrochemical polymerization is -0.5-1.5 V, preferably -0.4-1.3 V, further preferably 0-1.0 V, more preferably 0.2-0.7 V; the scanning speed is 80-120 mV / s, preferably 85-115 mV / s, further preferably 90-110 mV / s, more preferably 95-105 mV / s.

[0069] In the present application, after the electrochemical polymerization is finished, the film is cleaned in a mixed cleaning agent of dichloromethane and acetonitrile to remove monomers or oligomers on the surface of the film which do not undergo polymerization and residual electrolyte, and then is naturally dried in air for standby; the mixed cleaning agent comprises dichloromethane and acetonitrile, and the volume ratio of the dichloromethane and acetonitrile is preferably 8:1-4, preferably 8:1.2-3.5, further preferably 8:1.5-3, and more further preferably 8:2-2.5.

[0070] The technical solutions provided by the present application are described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0071] Example 1

[0072] Step 1): 4,7-dibromobenzothiazole (5.88 g, 20 mmol) was weighed into a 500 mL round-bottom flask, 200 mL of ethanol was added, and the mixture was cooled to -5°C. Sodium borohydride (14.00 g, 0.37 mol) was added to the obtained suspension in batches, and after 30 minutes of incubation and stirring, it was taken out and allowed to rise to room temperature in a natural state ， and stirred at a rate of 800 r / min for 14 h. After the reaction was completed, the reaction solvent was removed, and a large amount of deionized water was added for quenching. The reaction mixture was extracted with ethyl acetate, and saturated brine was used for cleaning three times. The organic layers were combined and dried over anhydrous Na2SO4, and about 4 times the mass of the reaction product of 200-300 mesh silica gel was added. Dichloromethane / petroleum ether (volume ratio 1:3) was used as the eluent, and 300-400 mesh silica gel was used as the stationary phase to perform column chromatography, and white solid was obtained, which was 3,6-dibromobenzene-1,2-diamine (4.75 g, yield 86%).

[0073] The nuclear magnetic resonance hydrogen spectrum thereof is characterized as follows: 1 H NMR (600 MHz, CDCl3) δ 6.86 (s, 2H), 3.91 (s, 4H).

[0074] Step 2): 3,6-dibromo-benzene-1,2-diamine (2.67 g, 10 mmol) and 1,4-butanedione (2.58 g, 30 mmol) prepared in step 1) were taken in a 100 mL two necked round flask. 50 mL of glacial acetic acid was added under nitrogen atmosphere. The reaction mixture was refluxed at 120 °C for 18 h and allowed to cool to room temperature. The reaction mixture was extracted with dichloromethane and washed with saturated brine three times. The organic layers were combined and dried over anhydrous Na2S04. About 7 times the mass of the reactants of 200-300 mesh silica gel was added and the sample was concentrated under vacuum. The product was purified by column chromatography using dichloromethane / pet ether (1:3) as eluent and 300-400 mesh fine silica gel as stationary phase to obtain 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline (2.67 g, 88% yield).

[0075] The H NMR of which is characterized as follows: 1 H NMR (600 MHz, CDC13) δ 7.86 (s, 2H), 2.85 (s, 6H).

[0076] Step 3): 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline (0.318 g, 1 mmol) prepared in step 1), tributyl(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxin-6-yl)stannane (1.42 g, 3 mmol) and 58 mg of tetrakis(triphenylphosphine)palladium were taken in a 100 mL two necked round flask. 20 mL of dry DMF was added under nitrogen atmosphere. The reaction mixture was refluxed at 155 °C for 18 h and allowed to cool to room temperature. The reaction mixture was extracted with dichloromethane and washed with saturated brine three times. The organic layers were combined and dried over anhydrous Na2S04. About 5 times the mass of the reactants of 200-300 mesh silica gel was added and the sample was concentrated under vacuum. The product was purified by column chromatography using dichloromethane / pet ether (1:2) as eluent and 300-400 mesh fine silica gel as stationary phase to obtain yellow solid which is quinoxaline derivative as 5,8-bis(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxin-6-yl)-2,3-dimethyl-4a,8a-dihydroquinoxaline.

[0077] The H NMR of which is characterized as follows: 1 H NMR (600 MHz, CDC13) δ 8.31 (s, 2H), 6.69 (s, 2H), 3.92 (s, 4H), 3.85 (s, 4H), 2.78 (s, 6H), 1.10 (s, 12H).

[0078] The quinoxaline derivative QWL (5.24 mg, 0.01 mmol) and tetrabutylammonium hexafluorophosphate (0.387 g, 1 mmol) prepared in this example were added to a 10 mL volumetric flask, and a mixed solvent of dichloromethane and acetonitrile (V / V = 8:2) was used as an electrolyte solvent to make up to 10 mL. After complete dissolution by ultrasonic treatment for 5 min, electrochemical polymerization was performed. The ITO glass (0.9*4 cm) was used as a working electrode, a platinum wire as a counter electrode, and an Ag / AgCl electrode as a reference electrode, and a film was polymerized by cyclic voltammetry with a voltage range of -0.3-1.2 V and a scanning speed of 100 mV / s. After the electro-polymerization was completed, the film was cleaned in a mixed cleaning agent of dichloromethane and acetonitrile (V / V = 8:2) to remove monomers or oligomers on the surface of the film that did not undergo polymerization and residual electrolyte, thereby obtaining the blue-transparent electrochromic material.

[0079] Figure 1 The polymerization curve of the quinoxaline derivative polymerized by cyclic voltammetry in this example.

[0080] The tetrabutylammonium hexafluorophosphate (0.387 g) was added to a 10 mL volumetric flask, and 8 mL of dichloromethane and 2 mL of acetonitrile were used as a blank solution to make up to 10 mL. The quinoxaline derivative polymer film prepared in this example was detected at different voltages using a UV-visible spectrophotometer to obtain Figure 2 From Figure 2 It can be seen that the prepared film can realize color change at a voltage of -0.3-0.7 V.

[0081] The response time of the quinoxaline derivative polymer film prepared in this example was detected at a wavelength of 610 nm to obtain Figure 3 From Figure 3 It can be seen that the coloring time of the film at a wavelength of 610 nm is 1.47 s, and the bleaching time is 0.54 s.

[0082] The kinetics of the quinoxaline derivative polymer film prepared in this example was tested at a wavelength of 610 nm to obtain Figure 4 From Figure 4 It can be seen that the optical contrast of the film at a wavelength of 610 nm is 38.25%, and there is no obvious decrease in contrast after 600 cycles, which is a blue-transparent new type of high-performance electrochromic material with great potential.

[0083] Example 2

[0084] Step 1): 3,6-dibromo-benzene-1,2-diamine (2.67 g, 10 mmol) and 1,4-butanedione (2.58 g, 30 mmol) purchased were added to a 100 mL two-necked round bottom flask, 50 mL of acetic acid was added under nitrogen protection, and reflux was maintained at 120 °C for 18 h, and then cooled to room temperature. The reaction mixture was extracted with dichloromethane, and washed with saturated brine three times. The organic layers were combined and dried over anhydrous Na2SO4, about 20 g of 200-300 mesh silica gel was added, and the sample was concentrated and stirred under vacuum. The sample was chromatographed on a column using dichloromethane / petroleum ether (volume ratio 1:3) as the eluent and 300-400 mesh silica gel as the stationary phase to obtain 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline (2.67 g, yield 88%).

[0085] Step 2): 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline (0.318 g, 1 mmol) prepared in step 1), tributyl(3,3-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxin-6-yl)stannane (1.42 g, 3 mmol), and 50 mg of tetrakis(triphenylphosphine)palladium were added to a 100 mL two-necked round bottom flask, 20 mL of super dry DMF was added under nitrogen protection, and reflux was maintained at 120 °C for 18 h, and then naturally cooled to room temperature. The reaction mixture was extracted with dichloromethane, and washed with saturated brine three times. The organic layers were combined and dried over anhydrous Na2SO4, about 10 g of 200-300 mesh silica gel was added, and the sample was concentrated and stirred under vacuum. The sample was chromatographed on a column using dichloromethane / petroleum ether (volume ratio 1:2) as the eluent and 300-400 mesh silica gel as the stationary phase to finally obtain the quinoxaline derivative.

[0086] The quinoxaline derivative QWL (7.86 mg, 0.015 mmol) prepared in this example and tetrabutylammonium hexafluorophosphate (0.774 g, 2 mmol) were added to a 20 mL volumetric flask, and a mixed solvent of dichloromethane and acetonitrile (V / V=7:3) was used as the electrolyte solvent to make up to 20 mL. After complete dissolution by ultrasonic treatment for 20 min, electrochemical polymerization was performed. An ITO glass (2.5*4 cm) was used as the working electrode, a platinum plate was used as the counter electrode, and an Ag / AgCl electrode was used as the reference electrode, and a film was polymerized by cyclic voltammetry with a voltage range of -0.4-1.3 V and a scanning speed of 50 mV / s. After the electrochemical polymerization was completed, the film was washed in a mixed cleaning agent of dichloromethane and acetonitrile (V / V=7:3) to remove monomers or oligomers on the surface of the film that did not undergo polymerization and residual electrolyte, thereby obtaining the blue-transparent electrochromic material.

[0087] The quinoxaline derivative and the preparation method thereof are provided by the application, and a blue-transparent electrochromic luminescent film can be obtained by using cyclic voltammetry to prepare a film of the quinoxaline derivative. The film can realize color change under a voltage of-0.3-0.7V, the optical contrast under a wavelength range of 610nm is 38.25%, the coloring time is 1.47s, and the bleaching time is 0.54s.

[0088] The above merely describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A blue-transparent electrochromic material prepared using a quinoxaline derivative, characterized in that, The quinoxaline derivative is 5,8-bis(3,3-dimethyl-3,4-dihydro-2H-thiopheno[3,4-b][1,4]dioxin-6-yl)-2,3-dimethyl-4a,8a-dihydroquinoxaline, and its structure is shown in formula (I): Formula (I); The preparation method of the blue-transparent electrochromic material comprises the following steps: The quinoxaline derivative shown in formula (I) is dissolved in a mixed solvent of dichloromethane and acetonitrile containing tetrabutylammonium hexafluorophosphate to obtain a mixed solution, and the blue-transparent electrochromic material can be prepared by electrochemical polymerization of the mixed solution.

2. The blue- transparent electrochromic material according to claim 1, characterized in that, The preparation method of the quinoxaline derivative comprises the following steps: Step 1): under a protective atmosphere, 3,6-dibromobenzene-1,2-diamine, 2,3-butanedione and a solvent are mixed to react to generate 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline; Step 2): 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline prepared in step 1) is mixed with tributyl(3,3-dimethyl-3,4-dihydro-2H-thiopheno[3,4-b][1,4]dioxin-6-yl)stannane, a solvent and a catalyst to react to generate the quinoxaline derivative shown in formula (I).

3. The blue- transparent electrochromic material according to claim 2, characterized in that, In step 1), the molar ratio of the 3,6-dibromobenzene-1,2-diamine and the 2,3-butanedione is 1:2.5-3.5; the solvent comprises acetic acid, and the use amount ratio of the solvent to the 3,6-dibromobenzene-1,2-diamine is 15-25 mL:1 g.

4. Blue- transparent electrochromic material according to claim 2 or 3, characterized in that, In step 1), the reaction is specifically that 3,6-dibromobenzene-1,2-diamine, 2,3-butanedione and a solvent are mixed and then refluxed at 100-140 DEG C for 15-24 h to obtain the target product 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline.

5. The blue- transparent electrochromic material according to claim 2 or 3, characterized in that, In step 2), the molar ratio of the 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline to the tributyl(3,3-dimethyl-3,4-dihydro-2H-thiopheno[3,4-b][1,4]dioxin-6-yl)stannane is 1:2.5-4; The catalyst comprises at least one of tetrakis(triphenylphosphine)palladium and palladium acetate; The solvent comprises N,N-dimethylformamide; The use amount ratio of the solvent to the 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline is 55-70 mL:1 g; The molar ratio of the catalyst to the 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline is 0.04-0.06:

1.

6. The blue- transparent electrochromic material according to claim 5, characterized in that, In step 2), the reaction is specifically that 5,8-dibromo-2,3-dimethyl-4a,8a-dihydroquinoxaline, tributyl(3,3-dimethyl-3,4-dihydro-2H-thiopheno[3,4-b][1,4]dioxin-6-yl)stannane, a catalyst and a solvent are mixed under a protective atmosphere and then refluxed at 140-175 DEG C for 12-24 h to obtain the quinoxaline derivative shown in formula (I).

7. The method of producing the blue-transparent electrochromic material according to claim 1, characterized by, The preparation method comprises the following steps: The quinoxaline derivative shown in formula (I) is dissolved in a mixed solvent containing tetrabutylammonium hexafluorophosphate, dichloromethane and acetonitrile to obtain a mixed solution, and the mixed solution is subjected to electrochemical polymerization to obtain the blue-transparent electrochromic material.

8. The preparation method according to claim 7, characterized in that The concentration of tetrabutylammonium hexafluorophosphate in the mixed solvent is 0.09-0.12 mol / L; the volume ratio of dichloromethane to acetonitrile is 8:1-4; and the concentration of the quinoxaline derivative shown in formula (I) in the mixed solution is 0.5-1.5 mmol / L.

9. The production method according to claim 7 or 8, characterized by, The polymerization voltage of the electrochemical polymerization is -0.5-1.5 V, and the scanning speed is 80-120 mV / s.

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