Multifunctional Electrochromic Monomer Compounds, Polymers and Applications Based on Calix[3]dihydroacridine

Abstract

The present invention belongs to the technical field of optoelectronic materials, and particularly relates to a multifunctional electrochromic monomer compound and polymer based on calix[3]dihydroacridine, a preparation method and application thereof. The structural formula of the multifunctional electrochromic monomer compound based on calix[3]dihydroacridine is shown as formula (I). The present invention uses calix[3]dihydroacridine as the central core and 3,4-ethylenedioxythiophene (EDOT) as the monomer of the electroactive polymerization unit, providing a three-branched material that is easy to form a network structure. Through electrochemical polymerization, a uniform and flat polymer film can be formed. This polymer film can achieve reversible switching from yellowish green to dark gray, with an optical contrast of 95.5%, response times of 1 s and 2.4 s, and excellent spectroelectrochemical stability in any wavelength band. It is an electrochromic material with good application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic materials, and particularly relates to a multifunctional electrochromic monomer compound and polymer based on calix[3]dihydroacridine, and a preparation method and application thereof. Background Art

[0002] Electrochromism (EC) refers to a phenomenon in which, under the action of an external electric field, a material undergoes stable and reversible changes in its optical properties (reflectivity, transmittance, absorptivity, etc.) due to oxidation-reduction reactions accompanied by the insertion and extraction of ions, and macroscopically exhibits reversible changes in appearance color and transparency. Materials with this phenomenon are called electrochromic materials. Due to the simple excitation method and obvious appearance performance, electrochromic materials have made great progress after decades of development. Electrochromic materials can be divided into inorganic electrochromic materials and organic electrochromic materials. Inorganic electrochromic materials have good chemical stability, but relatively long response times and single colors; while organic electrochromic materials are easy to modify and can obtain a variety of bright colors, and have been a hot topic in scientific research since their discovery.

[0003] As one of the organic electrochromic materials, conductive polymers have the advantages of easy structure modification, low cost, easy processing, rich color changes, fast response times, etc., and have become "star materials" in electrochromism, attracting extensive attention from researchers. At the same time, during the oxidation-reduction process, conductive polymers can reversibly store charges, thus having energy storage performance and being candidate electrode materials for pseudocapacitors and batteries. Therefore, based on conductive polymers, constructing a multifunctional electrode material with both electrochromic and energy storage properties can directly observe the energy storage state with the naked eye, thereby avoiding overcharging and over-discharging of energy storage devices and achieving the safe and sustainable intelligent development of electrochemical energy storage devices.

[0004] Thermally activated delayed fluorescence (TADF) materials, as a class of highly potential luminescent materials, have been widely used in the fields of electroluminescence, photocatalysis, organic lasers, bioimaging, and sensing in recent years. Theoretically, effective TADF depends on a small singlet-triplet energy gap (ΔE ST)To promote reverse intersystem crossing (RISC) within the molecule. For this purpose, the most commonly used design strategy is to spatially separate the HOMO and LUMO energy levels of the molecule in an electron donor-acceptor (D-A) structure. For example, the invention patent with the publication number CN112500556A discloses a donor-acceptor type electrochromic polymer. In the electrochromic polymer, the indacenodithiophene unit is the donor, the 2,1,3-benzothiadiazole unit is the acceptor, and four thiophene units are the bridging units. The electrochromic film prepared from the above electrochromic polymer has stable P-doping characteristics and can achieve a reversible transformation from red to transparent blue under a low potential drive. However, the contrast ratio, response rate, and stability still need to be improved. Moreover, there are few reports on electrochromic polymers from yellow-green to black-gray at present. Summary of the Invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a multifunctional electrochromic monomer compound, polymer based on calix[3]dihydroacridine for yellow-green to black-gray electrochromism, and its preparation method and application.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A multifunctional electrochromic monomer compound based on calix[3]dihydroacridine, the structural formula of which is shown in formula (I):

[0008]

[0009] The present invention also relates to a multifunctional electrochromic polymer based on calix[3]dihydroacridine, the structural formula of which is shown in formula (V):

[0010]

[0011] In formula (V), n represents the average degree of polymerization, and n takes 100 - 2000.

[0012] The preparation method of the multifunctional electrochromic monomer compound based on calix[3]dihydroacridine includes the following steps:

[0013] (1) 9,10-Dihydro-9,9-dimethylacridine reacts with p-bromoiodobenzene through Ullmann coupling reaction to obtain an acridine derivative DMAC-Ph-Br (II), and the structural formula of DMAC-Ph-Br is as follows:

[0014]

[0015] (2) DMAC-Ph-Br (II) reacts with paraformaldehyde through Friedel-Crafts alkylation reaction to obtain a calix[3]dihydroacridine macrocycle 3DMAC-Ph-Br (III), and the structural formula of 3DMAC-Ph-Br is as follows:

[0016]

[0017] (3) EDOT undergoes a substitution reaction with tributyltin chloride to obtain a stannylated EDOT derivative, EDOT-Sn(IV), and the structural formula of the EDOT-Sn is as follows:

[0018]

[0019] (4) 3DMAC-Ph-Br(III) and EDOT-Sn(IV) undergo a Stille coupling reaction under the catalysis of a palladium catalyst to obtain the target product 3DMAC-EDOT(I).

[0020] As an optimization of the above technical solution, step (1) is specifically as follows: 9,10-dihydro-9,9-dimethylacridine, p-bromoiodobenzene, copper(I) iodide, sodium tert-butoxide, 1,2-diaminocyclohexane, and 1,4-dioxane are sequentially added to a two-necked flask, and refluxed for 3 to 12 hours under a nitrogen atmosphere. After post-treatment, DMAC-Ph-Br(II) is obtained;

[0021] The molar ratio of 9,10-dihydro-9,9-dimethylacridine, p-bromoiodobenzene, copper(I) iodide, sodium tert-butoxide, and 1,2-diaminocyclohexane is 1:(1 to 1.2):(0.01 to 0.03):(1.8 to 2.2):(0.08 to 0.12);

[0022] The added volume of anhydrous 1,4-dioxane is 7 to 13 mL / g based on the mass of 9,10-dihydro-9,9-dimethylacridine;

[0023] The method of the post-treatment is specifically as follows: after the reaction is completed, the obtained reaction solution is poured into deionized water for mixing, and the precipitate is collected by filtration. Then, the precipitate is extracted with saturated sodium chloride and dichloromethane, the organic phase is collected and dried with anhydrous sodium sulfate. Finally, using petroleum ether and dichloromethane as the mobile phase, purification is carried out by silica gel column chromatography; in the mobile phase, the volume ratio of petroleum ether to dichloromethane is (3 to 8):1.

[0024] As an optimization of the above technical solution, step (2) is specifically as follows: DMAC-Ph-Br(II), paraformaldehyde, and dichloromethane are sequentially added to a single-necked flask. After stirring for 10 minutes, ferric chloride hexahydrate is added, and then the reaction is carried out at room temperature for 3 to 24 hours. After post-treatment, 3DMAC-Ph-Br(III) is obtained;

[0025] The molar ratio of DMAC-Ph-Br, paraformaldehyde, and ferric chloride hexahydrate is 1:(3 to 3.2):(0.1 to 0.12);

[0026] The added volume of dichloromethane is 200 - 300 mL / g based on the mass of monomer II;

[0027] The specific post - treatment method is as follows: after the reaction is completed, pour the obtained reaction solution into deionized water for mixing, filter to collect the precipitate, then extract the precipitate with saturated sodium chloride and dichloromethane, collect the organic phase and dry it with anhydrous sodium sulfate, and finally use petroleum ether and dichloromethane as the mobile phase and purify it by silica gel column chromatography; in the mobile phase, the volume ratio of petroleum ether to dichloromethane is (2 - 5):1.

[0028] As an optimization of the above - mentioned technical solution, step (3) is specifically as follows: under nitrogen protection, dissolve 3,4 - ethylenedioxythiophene (EDOT) in tetrahydrofuran, then add n - butyllithium at - 78 °C, stir for 1 hour and then add tributyltin chloride, restore to room temperature and stir for 24 hours, and obtain compound EDOT - Sn(IV) through post - treatment;

[0029] The molar ratio of the feed of EDOT, n - butyllithium, and tributyltin chloride is 1:(1 - 1.2):(1 - 1.6); among them, the n - butyllithium is a 1 - 3 mol / L n - butyllithium solution, and the tributyltin chloride is a 1 - 5 g / mL tributyltin chloride solution;

[0030] The added volume of tetrahydrofuran is 15 - 25 mL / g based on the mass of EDOT;

[0031] The specific post - treatment method is as follows: after the reaction is completed, separate and purify the obtained reaction solution through an alumina chromatography column.

[0032] As an optimization of the above - mentioned technical solution, step (4) is specifically as follows: under nitrogen protection, add monomer 3DMAC - Ph - Br(III), EDOT - Sn(IV), and palladium catalyst into a two - necked flask in sequence, then add DMF, stir and reflux for 48 hours, and obtain the target product 3DMAC - EDOT(I) through post - treatment;

[0033] The molar ratio of the feed of 3DMAC - Ph - Br, EDOT - Sn, and palladium catalyst is 1:(3 - 6):(0.001 - 0.01); among them, the palladium catalyst is any one of palladium acetate, tetrakis(triphenylphosphine)palladium, or dichlorobis(triphenylphosphine)palladium;

[0034] The added volume of DMF is 15 - 25 mL / g based on the mass of monomer III;

[0035] The specific method of the post-treatment is as follows: after the reaction is completed, the obtained reaction solution is poured into deionized water and mixed, the precipitate is collected by filtration, and then the precipitate is extracted with saturated sodium chloride and dichloromethane. The organic phase is collected and dried with anhydrous sodium sulfate. Finally, petroleum ether and dichloromethane are used as the mobile phase, and purification is carried out by silica gel column chromatography; in the mobile phase, the volume ratio of petroleum ether to dichloromethane is (0.5-2):1.

[0036] The present invention also relates to the application of the monomer compound in the preparation of a multifunctional electrochromic material.

[0037] Specifically, the application is as follows: 3DMAC-EDOT shown in formula (I) is dissolved in a mixed chromatographic grade solution of dichloromethane and acetonitrile, tetrabutylammonium perchlorate is added as an electrolyte, and electrochemical polymerization is carried out by cyclic voltammetry to form a film, and a multifunctional electrochromic material is prepared.

[0038] The volume ratio of dichloromethane to acetonitrile is (3-5):1; the concentration of 3DMAC-EDOT is 0.5-1 mmol / L; the concentration of tetrabutylammonium perchlorate is 0.05-0.1 mol / L;

[0039] The cyclic voltammetry electrochemical polymerization refers to carrying out electrochemical polymerization in a three-electrode system, using ITO conductive glass as the working electrode, a platinum wire as the counter electrode, and Ag / AgCl as the reference electrode to obtain a film attached to the ITO glass, which is a multifunctional electrochromic material based on calix[3]dihydroacridine; the scanning speed of the cyclic voltammetry is 100 mV / s, the voltage is 0-1.1 V, and the number of cycles is 5-10 cycles.

[0040] In summary, the present invention has the following beneficial effects:

[0041] 1. The present invention uses calix[3]dihydroacridine as the central core and 3,4-ethylenedioxythiophene (EDOT) as the monomer compound of the electroactive polymerization unit, providing a three-branched material that is easy to form a network structure. After electrochemical polymerization, a uniform and flat polymer film (p3DMAC-EDOT) can be formed, and at the same time, it exhibits good electrochemical properties such as electrochromism and energy storage.

[0042] 2. The polymer film prepared by electrochemical polymerization using the 3DMAC-EDOT compound shown in formula (I) of the present invention can achieve reversible switching from yellowish green to dark gray, with an optical contrast of 95.5%, response times of 1 s and 2.4 s, and excellent spectroelectrochemical stability in any wavelength band, and it is an electrochromic material with good application prospects.

[0043] 3. The polymer film (p3DMAC-EDOT) prepared by the present invention has a current density of 0.05 mA / cm 2At a current density of, it has a specific capacitance of 4.76 mF / cm 2 In addition, combining electrochromism with energy storage through a polymer film provides a research idea for developing intelligent energy storage devices that can monitor the energy storage state in real time, and also benefits future intelligent production and life as well as the sustainable development of energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is the synthetic route diagram of the calix[3]dihydroacridine derivative (3DMAC-EDOT) of the present invention;

[0045] Figure 2 is the electrochemical polymerization curve diagram of the calix[3]dihydroacridine derivative (3DMAC-EDOT) of the present invention;

[0046] Figure 3 is the UV-visible absorption spectrum diagram of the polymer film based on calix[3]dihydroacridine of the present invention at different voltages;

[0047] Figure 4 is the spectral kinetic stability diagram of the polymer film based on calix[3]dihydroacridine of the present invention in the 1100 nm band;

[0048] Figure 5 is the optical contrast and response time diagram of the polymer film based on calix[3]dihydroacridine of the present invention in the 1100 nm band;

[0049] Figure 6 is the charge-discharge curve diagram of the polymer film based on calix[3]dihydroacridine of the present invention at different current densities. DETAILED DESCRIPTION OF THE INVENTION

[0050] The technical solution of the present invention will be further described below with specific examples. However, the specific details of the examples are only for explaining the present invention and do not represent all the technical methods under the concept of the present invention. Therefore, it should not be construed as a limitation to the overall technical solution of the present invention.

[0051] Example 1: Synthesis of DMAC-Ph-Br

[0052] 1.14 g (5.45 mmol) of 9,10-dihydro-9,9-dimethylacridine, 1.7 g (6 mmol) of p-bromoiodobenzene, 0.021 g (0.11 mmol) of cuprous iodide, 1.05 g (10.9 mmol) of sodium tert-butoxide, 0.063 g (0.55 mmol) of 1,2-diaminocyclohexane, and 12 mL of anhydrous 1,4-dioxane were successively added to a 100 mL two-necked flask. The mixture was refluxed for 6 hours under a nitrogen atmosphere. After the reaction was completed, the reaction solution was poured into 100 mL of deionized water and mixed. The precipitate was collected by filtration, and then the precipitate was extracted with saturated sodium chloride solution and dichloromethane. The organic phase was collected and dried over anhydrous sodium sulfate. Finally, petroleum ether:dichloromethane (volume ratio 5:1) was used as the mobile phase, and purification was carried out by silica gel column chromatography to obtain DMAC-Ph-Br. The structural formula of DMAC-Ph-Br is shown in Formula II. 1 HNMR(400MHz,CDCl3)δ7.78(d,J=7.4Hz,2H),7.48(d,J=6.7Hz,2H),7.25(d,J=7.4Hz,2H),7.09–6.87(m,4H),6.27(d,J=7.3Hz,2H),1.66(d,J=32.9Hz,6H).

[0053]

[0054] Example 2: Synthesis of 3DMAC-Ph-Br

[0055] 1 g (2.75 mmol) of DMAC-Ph-Br, 0.247 g (8.25 mmol) of paraformaldehyde, and 250 mL of dry dichloromethane solution were successively added to a 500 mL single-necked flask. After stirring for 10 minutes, 0.074 g (0.275 mmol) of ferric chloride hexahydrate was added, and then the reaction was carried out at room temperature for 6 hours. After the reaction was completed, the reaction solution was poured into 100 mL of deionized water and mixed. The precipitate was collected by filtration, and then the precipitate was extracted with saturated sodium chloride solution and dichloromethane. The organic phase was collected and dried over anhydrous sodium sulfate. Finally, petroleum ether:dichloromethane (volume ratio 3:1) was used as the mobile phase, and purification was carried out by silica gel column chromatography to obtain the product monomer 3DMAC-Ph-Br. The structural formula of the monomer 3DMAC-Ph-Br is shown in Formula III. 1 H NMR(400MHz,CDCl3)δ7.75(t,J=10.0Hz,6H),7.25(t,J=9.4Hz,6H),7.14(d,J=12.9Hz,6H),6.90(t,J=9.1Hz,6H),6.23(t,J=7.7Hz,6H),3.89(s,6H),1.58(s,18H).

[0056]

[0057] Example 3: Synthesis of EDOT-Sn

[0058] Under nitrogen protection, 1 g (7.03 mmol) of EDOT was dissolved in 20 mL of anhydrous tetrahydrofuran, and then 3.37 mL (8.4 mmol, stored in hexane solution at 2.5 mol / L) of n-butyllithium solution was added dropwise at -78 °C. After stirring at this temperature for 1 hour, 2.97 g (9.14 mmol) of tributyltin chloride was added. After the addition of tributyltin chloride was completed, the mixture was stirred at room temperature for 24 hours. After the reaction was completed, the resulting reaction solution was separated and purified by an alumina chromatography column to obtain a crude product of the compound EDOT-Sn with a yield of 80%. The structural formula of the compound EDOT-Sn is as shown in Formula IV.

[0059]

[0060] Example 4: Synthesis of 3DMAC-EDOT

[0061] Under nitrogen protection, 0.5 g (0.44 mmol) of 3DMAC-Ph-Br, 0.95 g (2.2 mmol) of EDOT-Sn, and 40 mg (0.35 mmol) of tetrakis(triphenylphosphine)palladium were successively added to a two-necked round-bottom flask, and then 10 mL of anhydrous DMF was added. The reaction was refluxed with stirring for 48 hours. After the reaction was completed, the resulting reaction solution was poured into 100 mL of deionized water and mixed. The precipitate was collected by filtration, and then the precipitate was extracted with saturated sodium chloride solution and dichloromethane. The organic phase was collected and dried over anhydrous sodium sulfate. Finally, using petroleum ether:dichloromethane (volume ratio 1:1) as the mobile phase, purification was carried out by silica gel column chromatography to obtain the target product 3DMAC-EDOT. 1 H NMR (400 MHz, CDCl3) δ 7.97 (d, J = 8.4 Hz, 6H), 7.36 (d, J = 8.4 Hz, 6H), 7.14 (s, 6H), 6.90 (d, J = 8.3 Hz, 6H), 6.40 (s, 3H), 6.35 (d, J = 8.2 Hz, 6H), 4.45–4.26 (m, 12H), 3.89 (s, 6H), 1.47 (s, 18H).

[0062] Example 5: Electrochemical Polymerization of 3DMAC-EDOT

[0063] Dissolve the monomer 3DMAC-EDOT in a mixed chromatographic grade solution of dichloromethane and acetonitrile with a volume ratio of dichloromethane to acetonitrile of 8:2 and a concentration of 3DMAC-EDOT of 1 mmol / L. Then add tetrabutylammonium perchlorate as the electrolyte with a concentration of 0.1 mol / L. Perform cyclic voltammetry electrochemical polymerization in a three-electrode system (ITO conductive glass as the working electrode, platinum wire as the counter electrode, and Ag / AgCl as the reference electrode) to obtain an electrochromic polymer film (p3DMAC-EDOT) attached to the ITO glass, that is, a multifunctional electrochromic material based on calix[3]dihydroacridine; the scanning rate of the cyclic voltammetry is 100 mV / s, the voltage is 0 - 1.1 V, and the number of cycles is 8 cycles.

[0064] Example 6: Performance Test of Multifunctional Electrochromic Material Based on Calix[3]dihydroacridine

[0065] Add tetrabutylammonium perchlorate to a volumetric flask and make up the volume with chromatographic grade acetonitrile solution to a concentration of 0.1 mol / L, which is used as the electrolyte solution for testing. The ITO glass covered with the polymer film is used as the working electrode, platinum wire as the counter electrode, and Ag / AgCl as the reference electrode to form a three-electrode system. Use an electrochemical workstation to test the cyclic voltammogram of the polymer film in the voltage range of 0 - 1.2 V. The test results are as Figures 2 to 6 shown.

[0066] Figure 2 It is the electrochemical polymerization curve of calix[3]dihydroacridine derivative (3DMAC-EDOT). It can be seen that the current response signal increases with the increase in the number of cycles, indicating that the monomer is successfully polymerized on the surface of the ITO glass.

[0067] Figure 3 It is the spectral absorption change curve of the polymer film tested by the combined use of an electrochemical workstation - ultraviolet-visible spectrophotometer in the range of 0 - 1.2 V. It can be seen that the polymer film shows an absorption peak at about 400 nm in the neutral state, which belongs to the π-π* transition of the molecular structure. The two weak absorption peaks at about 500 nm and 620 nm belong to the absorption of the calix[3]dihydroacridine central core. At this time, the film shows yellowish-green. As the applied voltage increases, an absorption peak appears in the near-infrared region of the film, and the intensity of the absorption peak at about 400 nm becomes weaker. At this time, the film color changes from yellowish-green to blackish-gray.

[0068] Figure 4 and Figure 5The spectral kinetic changes, optical contrast, and response time diagrams of the polymer film at 0 V and 1.2 V in the 1100 nm band were measured using an electrochemical workstation-UV-visible spectrophotometer. It can be seen that: after 6000 s of cycling, the optical contrast of the film did not significantly decay, showing excellent electrochemical stability. In addition to the stable color change behavior, from Figure 4 it can be seen that the optical contrast of the film at 1100 nm is as high as 95.5%, and the color response times are 1 s and 2.4 s, respectively.

[0069] Figure 6 The charge-discharge performance of the polymer film at different current densities in the voltage range of 0.5 - 1.2 V was measured using an electrochemical workstation. It can be seen from this figure that: at a current density of 0.05 mA / cm 2 the film exhibits a specific capacitance of 4.76 mF / cm 2 ; when the current density increases to 0.5 mA / cm 2 the specific capacitance is 3.64 mF / cm 2 , remaining 76.5% of the initial value.

Claims

1. A multifunctional electrochromic monomer compound based on calix[3]dihydroacridine, characterized in that, Its structural formula is shown in formula (I):

2. A multifunctional electrochromic polymer based on calix[3]dihydroacridine, characterized in that Its structural formula is shown in formula (V): In formula (V), n represents the average degree of polymerization, and n takes 100 - 2000.

3. The preparation method of the multifunctional electrochromic monomer compound based on calix[3]dihydroacridine according to claim 1, characterized in that, It includes the following steps: (1) 9,10-Dihydro-9,9-dimethylacridine, p-bromoiodobenzene, copper(I) iodide, sodium tert-butoxide, 1,2-diaminocyclohexane, and 1,4-dioxane were successively added to a two-necked flask, refluxed for 3 - 12 hours under a nitrogen atmosphere, and aftertreatment gave DMAC-Ph-Br (II). The structural formula of DMAC-Ph-Br is as follows: The molar ratio of 9,10-dihydro-9,9-dimethylacridine, p-bromoiodobenzene, copper(I) iodide, sodium tert-butoxide, and 1,2-diaminocyclohexane is 1:(1 - 1.2):(0.01 - 0.03):(1.8 - 2.2):(0.08 - 0.12); the added volume of anhydrous 1,4-dioxane is 7 - 13 mL / g based on the mass of 9,10-dihydro-9,9-dimethylacridine. (2) DMAC-Ph-Br (II), paraformaldehyde, and dichloromethane were successively added to a single-necked flask. After stirring for 10 minutes, ferric chloride hexahydrate was added, and then the reaction was carried out at room temperature for 3 - 24 hours. Aftertreatment gave calix[3]dihydroacridine macrocycle 3DMAC-Ph-Br (III). The structural formula of 3DMAC-Ph-Br is as follows: The molar ratio of DMAC-Ph-Br, paraformaldehyde, and ferric chloride hexahydrate is 1:(3 - 3.2):(0.1 - 0.12); the added volume of dichloromethane is 200 - 300 mL / g based on the mass of monomer II. (3) EDOT undergoes a substitution reaction with tributyltin chloride to obtain the tinated EDOT derivative EDOT-Sn (IV). The structural formula of EDOT-Sn is as follows: (4) 3DMAC-Ph-Br (III) and EDOT-Sn (IV) undergo a Stille coupling reaction under the catalysis of a palladium catalyst to obtain the target product (I).

4. The method according to claim 3, characterized in that Step (3) is specifically: Under nitrogen protection, EDOT is dissolved in tetrahydrofuran, then n-butyllithium is added at -78 °C, stirred for 1 hour, and then tributyltin chloride is added. After returning to room temperature and stirring for 24 hours, aftertreatment gives compound EDOT-Sn (IV); the molar ratio of EDOT, n-butyllithium, and tributyltin chloride is 1:(1 - 1.2):(1 - 1.6); the added volume of tetrahydrofuran is 15 - 25 mL / g based on the mass of EDOT.

5. The method according to claim 3, characterized in that Step (4) is specifically: Under nitrogen protection, monomer 3DMAC-Ph-Br (III), EDOT-Sn (IV), and a palladium catalyst are successively added to a two-necked flask, then DMF is added, and the mixture is stirred and refluxed for 48 hours. Aftertreatment gives the target product (I).

6. Use of the monomer compound according to claim 1 in the preparation of an electrochromic material, and the use is as follows: dissolving the compound shown in formula (I) in a mixed chromatographic grade solution of dichloromethane and acetonitrile, adding tetrabutylammonium perchlorate as an electrolyte, and electrochemically polymerizing into a film by cyclic voltammetry to prepare an electrochromic material.

7. The use according to claim 6, wherein the volume ratio of dichloromethane to acetonitrile is (3 - 5):1; the concentration of the compound shown in formula (I) is 0.5 - 1 mmol / L; the concentration of tetrabutylammonium perchlorate is 0.05 - 0.1 mol / L.

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