A thiophene quinoline compound, a preparation method thereof, a polymer, an electrochromic material and an electrochromic device

Abstract

The application discloses a thiophene quinoline compound, a preparation method thereof, a polymer, an electrochromic material and an electrochromic device. 1～18 The thiophene quinoline compound has a structural formula shown in formula (I): wherein R1, R2, R3 and R4 are independently selected from halogen, C 6～20 alkyl, C 6～20 aryl or aryl substituted by halogen, nitro, amino, hydroxyl or carboxyl; the polymer polymerized by the thiophene quinoline compound has the advantages of low driving voltage, high contrast, fast switching time and good stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochromic materials, and in particular to a thiophene quinoline compound, a preparation method thereof, a polymer, an electrochromic material and an electrochromic device. BACKGROUND

[0002] Electrochromism (EC) refers to the reversible change of color, absorbance and transmittance of a material under the action of an applied voltage. The material with such a color change performance is called an electrochromic material. Compared with other electrochromic materials, electrochromic conjugated polymers have a wide absorption spectrum (from ultraviolet to visible light, and the absorption range of the infrared region), high optical contrast and fast switching speed, making them excellent candidates for green building intelligent windows, anti-glare mirrors, electronic displays, smart glasses and wearable clothing.

[0003] The electrochromism of the conjugated polymer is a redox process, involving the removal or injection of electrons from the electrochromic conjugated polymer (p-doping or n-doping, respectively), leading to the formation of polarons and bipolarons, and causing structural changes in the polymer backbone. Traditional polythiophenes usually have poor solubility and are too tricky for further processing. Existing electrochromic polymers have high driving voltage, low contrast, slow switching time, and poor stability.

[0004] Therefore, it is urgent to provide a compound monomer, so that the polymer polymerized from the compound monomer has low driving voltage, high contrast, fast switching time and good stability. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes, in a first aspect, a thiophene quinoline compound, and a polymer polymerized from the thiophene quinoline compound has the advantages of low driving voltage, high contrast, fast switching time and good stability.

[0006] The present application further provides, in a second aspect, a preparation method of the thiophene quinoline compound.

[0007] The present application further provides, in a third aspect, a polymer.

[0008] The present application further provides, in a fourth aspect, a preparation method of the polymer.

[0009] The present application further provides, in a fifth aspect, an electrochromic material.

[0010] The present application further provides, in a sixth aspect, an electrochromic device.

[0011] According to the first aspect of the present application, a thienyl-quinoxaline compound is provided, which has a structural formula as shown in formula (I):

[0012]

[0013] wherein R1, R2, R3 and R4 are independently selected from halogen, C 1～18 alkyl, C 6～20 aryl or aryl substituted by halogen, nitro, amino, hydroxyl or carboxyl;

[0014] X1 and X2 are independently selected from halogen;

[0015] π is selected from thienyl or 3,4-ethylenedioxythienyl;

[0016] D is selected from thienyl or 3,4-ethylenedioxythienyl.

[0017] According to the thienyl-quinoxaline compound provided by the present application, at least the following advantages are achieved:

[0018] The polymer of the thienyl-quinoxaline compound provided by the present application has the advantages of low driving voltage, high contrast, fast switching time and good stability.

[0019] According to a preferred embodiment of the present application, R1, R2, R3 and R4 are independently selected from C 4～15 alkyl, C 6～20 aryl or aryl substituted by halogen, nitro, amino, hydroxyl or carboxyl.

[0020] According to a preferred embodiment of the present application, the thienyl-quinoxaline compound is selected from one of the following structural formulas:

[0021]

[0022] According to the second aspect of the present application, a preparation method of the thienyl-quinoxaline compound is provided, which comprises the following steps:

[0023] mixing the acceptor, compound 1, solvent and catalyst to perform Stille coupling reaction under the atmosphere of protective gas to obtain the thienyl-quinoxaline compound;

[0024] The compound 1 is selected from tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane or tributyl(2-thienyl)stannane.

[0025] The acceptor has a structural formula as shown in formula (II):

[0026]

[0027] According to a preferred embodiment of the present application, the mass ratio of the acceptor to compound 1 is 1:(1-5).

[0028] According to a preferred embodiment of the present application, the mass ratio of the acceptor to compound 1 is 1:(1.4-4).

[0029] According to a preferred embodiment of the present application, the mass ratio of the acceptor to the catalyst is 1:(0.03-0.0625).

[0030] According to a preferred embodiment of the present application, the temperature of the Stille coupling reaction is 70-130℃.

[0031] According to a preferred embodiment of the present application, the temperature of the Stille coupling reaction is 90-120℃.

[0032] According to a preferred embodiment of the present application, the time of the Stille coupling reaction is 8-24 hours.

[0033] According to a preferred embodiment of the present application, the time of the Stille coupling reaction is 12-24 hours.

[0034] According to a preferred embodiment of the present application, the catalyst comprises at least one of Pd(PPh3)4 (i.e. palladium tetra(triphenylphosphine)), palladium chloride, palladium acetate or CuI.

[0035] According to a preferred embodiment of the present application, the solvent comprises at least one of N,N-dimethylformamide, benzene, acetone or ethanol.

[0036] According to a preferred embodiment of the present application, the protective gas atmosphere comprises nitrogen or a rare gas.

[0037] According to a preferred embodiment of the present application, after the Stille coupling reaction, a step of washing is further performed; the reagent for the washing is preferably a sodium chloride solution; after the washing, a step of chromatographic separation and purification is further performed; the chromatographic separation and purification is preferably performed by using a silica gel column.

[0038] The third aspect of the present application provides a polymer, wherein the monomer of the polymer is the thienyl-quinoxaline compound according to the first aspect of the present application; and the polymer has the structure shown in formula (II):

[0039]

[0040] According to the polymer provided by the embodiments of the present application, at least the following beneficial effects are achieved:

[0041] (1) The polymer of the present application takes 2,3-bis(thiophen-2-yl)quinoxaline as an acceptor, thiophene or 3,4-ethylenedioxythiophene (EDOT) as a π bridge, and a thiophene derivative as a donor to form a D-π-A-π-D structure. 2,3-bis(thiophen-2-yl)quinoxaline has strong electron-withdrawing ability, which can enhance the intramolecular charge transfer of the D-A-D conjugated polymer. EDOT as a strong electron-donating group can reduce the starting oxidation potential of the monomer, reduce the optical band gap of the conjugated polymer, and improve the electrochromic performance.

[0042] (2) The polymer of the present application can observe stable reversible color changes from brown green to emerald green, or from brown yellow to gray under the action of an applied voltage, and has good electrochromic performance such as high contrast, high coloring efficiency, and fast switching time.

[0043] According to a preferred embodiment of the present application, R1, R2, R3 and R4 are independently selected from C 4～15 alkyl, C 6～20 aryl or aryl substituted by halogen, nitro, amino, hydroxyl or carboxyl.

[0044] According to a preferred embodiment of the present application, n represents the average degree of polymerization, and n is 10-5000.

[0045] According to a preferred embodiment of the present application, n is 10-3000.

[0046] According to a preferred embodiment of the present application, the polymer is selected from one of the following structural formulas:

[0047]

[0048] The fourth aspect of the present application provides a preparation method of a polymer, comprising the following steps:

[0049] The thiophene quinoxaline compound of the first aspect of the present application and the electrolyte solution are mixed, and an electrochemical polymerization reaction is carried out by a constant potential method.

[0050] According to a preferred embodiment of the present application, the concentration of the thiophene quinoxaline compound in the solvent is 1-12 mmol·L -1 .

[0051] According to a preferred embodiment of the present application, the concentration of the thiophene quinoxaline compound in the solvent is 1-10 mmol·L -1 .

[0052] According to a preferred embodiment of the present application, the concentration of the electrolyte solution is 0.05-0.3 mol·L -1 .

[0053] According to a preferred embodiment of the present application, the concentration of the electrolyte solution is 0.06-0.1 mol·L -1 .

[0054] According to a preferred embodiment of the present application, the electrochemical polymerization reaction adopts a three-electrode system; wherein, an Ag / AgCl electrode is used as a reference electrode, a platinum wire is used as a counter electrode, and a Pt / ITO conductive glass is used as a working electrode.

[0055] According to a preferred embodiment of the present application, the organic solvent is at least one of dichloromethane, trichloromethane or acetonitrile.

[0056] According to a preferred embodiment of the present application, the electrolyte in the electrolyte solution is at least one of tetrabutylammonium hexafluorophosphate, tetrabutylammonium tetrafluoroborate or lithium perchlorate.

[0057] The fifth aspect of the present application provides an electrochromic material, comprising the polymer of the third aspect of the present application.

[0058] The sixth aspect of the present application provides an electrochromic device, comprising the polymer of the third aspect of the present application or the electrochromic material of the fifth aspect of the present application.

[0059] According to a preferred embodiment of the present application, the electrochromic device comprises at least one of a display, electrochromic glass, a smart window or a rearview mirror.

[0060] Other features and advantages of the present application will be set forth in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0061] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0062] Figure 1 The figure is a spectroelectrochemical graph of the polymer in MeCN-Bu4NPF6(0.1 mol / L) system.

[0063] Figure 2 The figure is a transmittance-time curve of the polymer in MeCN-Bu4NPF6(0.1 mol / L) system.

[0064] Figure 3 The figure is a short-term memory effect of the polymer in MeCN-Bu4NPF6(0.1 mol / L) system. DETAILED DESCRIPTION

[0065] The following are specific embodiments of the present application, and the technical solutions of the present application are further described in conjunction with the embodiments, but the present application is not limited to these embodiments.

[0066] The reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the technical field unless otherwise specified.

[0067] Example 1

[0068] This example provides a thienylquinoxaline compound I-1, the reaction equation and preparation method thereof are as follows:

[0069]

[0070] Under nitrogen atmosphere, 5,8-bis(5-bromothiophen-2-yl)-2,3-bis(5-chloro-4-octylthiophen-2-yl)-6,7-difluoroquinoxaline (0.14 g, 0.148 mmol), tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)stannane (0.1 g, excess), and catalyst Pd(PPh3)4(0.017 g, 0.0148 mmol) were placed in a 250 mL single-necked flask, toluene (32 mL) and N,N-dimethylformamide (8 mL) were added and stirred uniformly, heated to 120°C, and condensed to reflux for 48 hours. After the system was cooled, the product was poured into saturated brine, extracted with dichloromethane 4-5 times, then a small amount of water was added to wash the organic layer, and then the solvent was removed by reduced pressure distillation, rotary evaporation, and separation was performed on a silica gel chromatography column with eluent (DCM:PE=1:5), and 34.2 mg of black powder product was obtained by purification, with a yield of 21.6%.

[0071] The nuclear magnetic resonance hydrogen spectrum data of the product is: 1 H NMR (400 MHz, Chloroform-d) δ 7.57 (d, J = 4.0 Hz, 2H), 7.17 (s, 2H), 7.00 (d, J = 4.1 Hz, 2H), 6.13 (s, 2H), 4.21 (d, J = 53.1 Hz, 8H), 2.42 (t, J = 7.8 Hz, 4H), 1.42 (q, J = 7.4 Hz, 4H), 1.21 (d, J = 12.9 Hz, 24H), 0.80 (t, J = 6.7 Hz, 6H).

[0072] Example 2

[0073] This example provides a thienylquinoxaline compound I-2, the reaction equation and preparation method thereof are as follows:

[0074]

[0075] A 250 mL single-necked flask was charged with 5,8-bis(5-bromothiophen-2-yl)-2,3-bis(4-chloro-5-(2-ethylhexyl)thiophen-2-yl)-6,7-difluoroquinoxaline (0.07 g, 0.074 mmol), tributyl(2,3-dihydro[3,4-b][l,4]dioxin-5-yl)stannane (0.076 g, 0.178 mmol), and catalyst Pd(PPh3)4(0.0086 g, 0.0074 mmol) under nitrogen atmosphere, stirred well after adding TOL (32 mL) and DMF (8 mL), heated to 120°C and condensed to reflux for 48 hours. After the system was cooled, the product was poured into saturated brine, extracted with dichloromethane 4-5 times, the organic layer was washed with a small amount of water, and then the solvent was removed by distillation under reduced pressure, rotary evaporation, and separation on a silica gel column with eluent (DCM:PE = 1:5) to obtain 15.7 mg of the product in the form of purple black powder with a yield of 19.86%.

[0076] The product had the following nuclear magnetic resonance hydrogen spectrum data: 1 H NMR (400 MHz, Chloroform-d) δ 7.86 (d, J = 4.1 Hz, 2H), 7.40 (s, 2H), 7.29 (d, J = 4.1 Hz, 2H), 6.21 (s, 2H), 4.27 (d, J = 35.0 Hz, 8H), 2.74 (d, J = 7.1 Hz, 4H), 1.71 (q, J = 6.1 Hz, 2H), 1.24 (dd, J = 24.6, 19.8 Hz, 20H), 1.00 - 0.65 (m, 15H).

[0077] Example 3

[0078] This example provides a polymer II-1, whose reaction equation and preparation method are as follows:

[0079]

[0080] The electrochemical polymerization was performed in a one-chamber three-electrode system, the working electrode was ITO conductive glass, the counter electrode was platinum sheet, and the reference electrode was Ag / AgCl electrode (Ag wire was electrolyzed on the surface to generate AgCl coating in 6 mol / L HCl solution with constant potential 1.5 V, 100 s).

[0081] The thiophene quinoxaline compound I-1 prepared in Example 1 (0.01 mol / L) was used as the polymerization monomer, tetrabutylphosphonium hexafluoride (0.1 mol / L) was used as the electrolyte, and the constant potential method was used for polymerization, the polymerization potential was 0.75 V, the polymerization time was 30 s, and the polymer film obtained by electrodeposition was washed with acetonitrile to obtain the product.

[0082] (1) Study on electrochromic properties

[0083] The polymer film II-1 deposited on ITO conductive glass was placed in a three-electrode electrolytic cell containing a 0.1 mol / L tetrabutylphosphine dichloromethane solution. The working electrode was the ITO conductive glass with polymer film II-1 attached, the counter electrode was a platinum sheet, and the reference electrode was an Ag / AgCl electrode. The voltage applied to the working electrode was adjusted using a potentiostatic method via an electrochemical workstation, and the changes in the absorption spectrum of polymer II-1 at different voltages were recorded using a UV-Vis spectrometer, thus obtaining the spectroelectrochemical spectrum of the polymer.

[0084] The spectroelectrochemical spectra of polymer II-1 in the MeCN-Bu4NPF6 (0.1 mol / L) system are shown below. Figure 1 As shown in (a), and combined with visual observation of the color change of the polymer material, it can be seen that as the potential increases, the color of the polymer material changes from brownish-green to emerald green (it is brownish-green in the completely dedoped state). This is because the neutral polymer material has an absorption peak in both the cyan and red light regions, and the neutral polymer material appears brownish-green. After the polymer material is oxidized, the absorption peaks in the cyan and red light regions gradually weaken and eventually disappear completely, while the absorption peak in the near-infrared region appears and gradually rises, and the color also changes to emerald green.

[0085] (2) The transmittance of the polymer film in the doped and neutral states at a specific wavelength under a square wave potential is measured by using a UV-Vis spectrophotometer, thereby calculating the optical contrast, response time, etc. The UV-Vis spectrophotometer records the time-transmittance curve, and the electrochemical workstation records the time-current curve. The coloring efficiency can also be calculated based on these two curves.

[0086] The transmittance-time curves of polymer II-1 at 1100 nm, 890 nm, 700 nm, and 472 nm were tested. The response time and coloring efficiency calculated from the time-transmittance curves are shown in Table 1. As can be seen from Table 1, polymer II-1 has a fast response time and high coloring efficiency.

[0087] Table 1 Electrochromic parameters

[0088]

[0089] The optical transmittance of polymer II-1 was studied using chronoamperometry at wavelengths of 1100 nm, 890 nm, 700 nm, and 472 nm. During the experiment, the time interval between potential step changes was 5 s. Figure 2(a) shown. At four wavelengths, polymer II-1 exhibited certain optical contrast and good optical stability; in addition, the optical transmittance had a great influence on the color change of the polymer material, and polymer II-1 could change from brown-green in the fully dedoped state to emerald green in the doped state.

[0090] Using the constant potential method, the working electrode was applied with a voltage of 10s and a voltage of 2s every 100s by the electrochemical working station, and the change trend of the transmittance of the polymer under the maximum absorption peak in the oxidized state and the reduced state was recorded by the ultraviolet visible spectrometer, that is, the short-term memory effect spectrum of the polymer was obtained.

[0091] The short-term memory effect of polymer II-1 was tested at a wavelength of 1100nm, and the transmittance change of the polymer in the neutral state and the doped state was recorded by applying a voltage of-0.2V and 1.0V respectively, as shown in Figure 3 (a), it was found that the transmittance change of polymer II-1 in the neutral state was 2.25%, and the transmittance change in the doped state was 1.33%, which indicated that the polymer II-1 had excellent short-term memory effect.

[0092] Example 4

[0093] This example provides a polymer II-2, whose reaction equation and preparation method are as follows:

[0094]

[0095] The electrochemical polymerization was carried out in a one-chamber three-electrode system, the working electrode was ITO conductive glass, the counter electrode was platinum sheet, and the reference electrode was Ag / AgCl electrode (silver wire in 6mol / L HCl solution constant potential 1.5V, 100s electrolysis surface to generate AgCl coating).

[0096] 10mL refined dichloromethane was used as the electrolyte, the thiophene quinoline compound I-2 (0.01mol / L) prepared in Example 2 was used as the polymerization monomer, and tetrabutylphosphonium hexafluoride (0.1mol / L) was used as the electrolyte. The polymerization was carried out by constant potential method, the polymerization potential was 0.85V, the polymerization time was 35s, and the polymer film obtained by electrodeposition was washed with acetonitrile.

[0097] Study on electrochromic performance

[0098] (1) The spectroelectrochemical diagram of polymer II-2 in MeCN-Bu4NPF6 (0.1mol / L) system was tested, as shown in Figure 1(b) and combined with the naked eye observation of the color change of the polymer material, it can be seen that as the potential increases, the color of the polymer material changes from brown yellow to gray (brown yellow in the completely dedoped state), which is due to the fact that the neutral state of the polymer material has an absorption peak in the cyan region and the red region, and the color of the neutral state of the polymer material is brown yellow; after the polymer material is oxidized, the absorption peaks in the cyan region and the red region gradually weaken and finally disappear, and the near-infrared region absorption peak appears and gradually rises, and the color also changes to gray.

[0099] (2) The transmittance-time curves of polymer II-2 at 1100 nm, 935 nm, 715 nm and 475 nm were tested. The response time and coloring efficiency calculated from the time-transmittance curve are shown in Table 2. From Table 2, it can be seen that the optical contrast of polymer II-2 is high, and the coloring efficiency is high.

[0100] Table 2 Electrochromic parameters of polymer II-2

[0101]

[0102] The optical transmittance of polymer II-2 at 1100 nm, 935 nm, 715 nm and 475 nm was studied by chronosorption method, and the time interval of the potential step change was 5 s during the experiment, as shown in Figure 2 (b). At the three wavelengths, polymer II-2 shows good optical contrast and good optical stability; in addition, the optical transmittance has a great influence on the color change of polymer II-2, and polymer II-2 can change from brown yellow in the completely dedoped state to gray in the doped state.

[0103] (3) The short-term memory effect of polymer II-2 was tested at 1100 nm, and -0.3 V and 1.1 V voltages were applied, respectively, and the transmittance change of polymer II-2 in the neutral state and the doped state was recorded, as shown in Figure 3 (b). It is found that the transmittance change of polymer II-2 in the neutral state is 3.49%, and the transmittance change in the doped state is 0.56%, which indicates that the polymer II-2 has good short-term memory effect.

[0104] The above is a detailed description combined with the embodiments of the present application, but the present application is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the purpose of the present application.

Claims

1. A thienylquinoxaline compound, characterized in that, It has the structural formula shown in equation (I): ； Among them, R1, R2, R3, and R4 are independently selected from halogens, C 1~18 Alkyl groups; X1 and X2 are independently selected from halogens; π is selected from thiophene; D is selected from 3,4-ethylenedioxythiophene.

2. The thienylquinoxaline compound according to claim 1, characterized in that, The thiophene-quinoxaline compounds are selected from the following structural formulas: 。 3. The method for preparing thienylquinoxaline compounds according to claim 1 or 2, characterized in that, Includes the following steps: Under a protective gas atmosphere, the acceptor, compound 1, solvent and catalyst were mixed and subjected to Stille coupling reaction to obtain thienylquinoxaline compounds; Compound 1 is selected from tributyl(2,3-dihydro[3,4-b][1,4]dioxin-5-yl)tinane or tributyl(2-thienyl)tin; The structural formula of the receptor is as follows: 。 4. The preparation method according to claim 3, characterized in that, The mass ratio of the receptor to compound 1 is 1:(1~5).

5. The preparation method according to claim 3, characterized in that, The mass ratio of the acceptor to the catalyst is 1:(0.03~0.0625).

6. The preparation method according to claim 3, characterized in that, The Stille coupling reaction is carried out at a temperature of 70~130℃.

7. A polymer, characterized in that, The monomer of the polymer is a thiophene-quinoxaline compound as described in claim 1 or 2; the polymer has the structure shown in formula (II): ；n＞0。 8. The method for preparing the polymer according to claim 7, characterized in that, Includes the following steps: The thienylquinoxaline compound of claim 1 or 2 is mixed with an organic solvent and an electrolyte solution and obtained by electrochemical polymerization using a constant potential method.

9. An electrochromic material, characterized in that, Includes the polymer described in claim 7.

10. An electrochromic device, characterized in that, Includes the polymer of claim 7 or the electrochromic material of claim 9.

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