An electrochromic compound, method of preparation and use

Abstract

The application relates to the technical field of electrochromic materials, and provides an electrochromic compound which takes tetrapyridine as a basic framework, can introduce benzene, thiophene, pyrrole, furan and derivatives thereof into pyridine, and can regulate electrochemical properties of the material by expanding a conjugated structure; and an asymmetric structure containing an anchoring group is designed; the anchoring group can modify a nano electrode, the electrochromic material is fixed at the electrode end, the color changing speed is not affected by the diffusion structure of the material itself, unsaturated hydrocarbon structures are introduced on the other side, the solubility of the material can be improved, and the conjugated degree of the material is further increased. The compound has the advantages of rich color, fast color changing speed and long service life as the electrochromic material. The device composed of the above material has the advantages of rich color change, high contrast, fast response speed and long service life of the device.

Description

Technical Field

[0001] This invention relates to the field of electrochromic materials technology, and in particular to an electrochromic compound and its preparation method, an electrochromic device and its preparation method and application. Background Technology

[0002] Electrochromic materials are materials whose optical absorption changes reversibly under the influence of an applied potential, showing great promise in applications such as displays, smart windows, and optical camouflage. They can be classified into inorganic and organic electrochromic materials based on their inherent properties. Common inorganic electrochromic materials include tungsten trioxide (WO3) and Prussian blue (PB), while organic electrochromic materials include viologen (MV). 2+ Electrochromic devices, such as conjugated polymers (PEDOT, P3HT), exhibit better user control and color adjustment capabilities compared to thermochromic or photochromic devices, making this technology a popular research topic.

[0003] Violet, due to its fading state (MV) 2+ ) and shading state (MV) +· Its superior contrast ratio and low drive voltage make it widely used in car rearview mirrors.

[0004] However, current viologen color-changing materials need improvement, mainly for two reasons. First, small-molecule viologen devices have poor stability. Due to the strong -π interaction between ions, viologen free radical cations dimerize, leading to an irreversible fading process. Second, their color switching speed is too slow. The fading rate of viologen is affected by its diffusion rate; most viologen has a large viscosity and molecular weight, resulting in a slow response speed, making it unsuitable for practical applications. Summary of the Invention

[0005] Currently, commercially available electrochromic materials are mainly viologen compounds, which result in devices with slow response speeds and low stability. While these materials are already used in automotive rearview mirrors, outdoor applications require greater color selectivity and high sensitivity, thus demanding higher requirements for fading speed and device stability. Current electrochromic materials cannot yet meet the performance requirements of outdoor smart windows.

[0006] To address the aforementioned shortcomings, this invention provides an electrochromic compound, its preparation method, and its application. Devices based on the aforementioned materials are of great significance for applications requiring rich colors and rapid response.

[0007] The technical solution of the present invention is achieved in the following way: providing an electrochromic compound, the structural formula of which is shown below:

[0008]

[0009] R1 is one of the following: phosphate group (-PO(OH)2), silica group (-Si(OH)3), and acetate group (-COOH);

[0010] M is a direct link, or M is selected from benzene, 1,4-dibromo-2,5-bis(trifluoromethyl)benzene, thiophene, furan, phenylpyrrole, thienothiophene, 2,3-dihydrothieno[3,4-b][1,4]dioxin, thiazothiazole and their substituted derivatives;

[0011] R2 is an alkenyl or alkynyl group;

[0012] m and n can be independent integers between 0 and 12;

[0013] X - Selected from chloride ion, bromide ion, iodide ion, trifluoromethanesulfonate anion, perchlorate anion, and tetrafluoroborate anion.

[0014] Preferably, in one embodiment of the present invention, the electrochromic compound has the structure shown in formulas (A) to (F):

[0015]

[0016] Preferably, in one embodiment of the present invention, R2 of the electrochromic compound is an unsaturated alkenyl or alkynyl group; the alkenyl group includes vinyl (-CH=CH2) and allyl (-CH2CH=CH2); the alkynyl group includes ethynyl (-C≡CH), propynyl (-CH2C≡CH), and 1-propynyl (-C≡C-CH3).

[0017] Preferably, in one embodiment of the invention, the electrochromic compound has any one of the structural formulas shown in formulas (1) to (9):

[0018]

[0019] This invention also provides a method for preparing an electrochromic compound, comprising the following steps:

[0020] Compound a reacts with compound b under reflux to obtain compound c, then compound c reacts with compound d under reflux in an organic solvent to obtain compound e, and finally acidification and hydrolysis are performed to obtain the final electrochromic compound.

[0021]

[0022] Wherein, M is a direct link, or M is selected from benzene, 2,5-bis(trifluoromethyl)benzene, thiophene, furan, phenylpyrrole, thienothiophene, 2,3-dihydrothieno[3,4-b][1,4]dioxin, thiazothiazole and their substituted derivatives;

[0023] The structural formula of compound b is R3-(CH2). m -R4, where m is an integer between 0 and 12, R3 is any one of I, Br, and Cl, and R4 is one of a monosubstituted phosphate ester (-PO(OCH2CH3)2), methylsiloxane (-Si(OCH3)3), or ethyl acetate (-COOCH2CH3);

[0024] The structural formula of compound d is R2-(CH2). n -R5, where n is an integer between 0 and 12, R2 is an alkenyl or alkynyl group, and R5 is any one of I, Br, and Cl.

[0025] Preferably, in one embodiment of the present invention, m is 2 or 3, and n is 2 or 3.

[0026] Preferably, in one embodiment of the present invention, the compound b has one of the following structural formulas:

[0027]

[0028] The structural formula of compound d is one of the following:

[0029]

[0030] Preferably, in one embodiment of the present invention, M is benzene substituted at positions 2 and / or 5 by any one of F, CF3, OCH3, or OCF3;

[0031] Alternatively, M can be pyrrole with the N-position substituted by benzene, benzyl, or their derivatives;

[0032] Alternatively, M can be a pyrrole or thiophene of any one of CF3, OCH3, or OCF3 at positions 2 and / or 3.

[0033] The present invention also provides an electrochromic device, comprising a first conductive layer, a second conductive layer, a semiconductor layer, an electrochromic layer, and an electrolyte layer between the first conductive layer and the second conductive layer; wherein the electrochromic layer uses the aforementioned electrochromic compound, or uses an electrochromic compound obtained by the aforementioned preparation method.

[0034] Preferably, in one embodiment of the present invention, the first conductive layer and the second conductive layer comprise one of FTO and ITO conductive glass; the semiconductor layer comprises one of titanium dioxide and tin dioxide.

[0035] Preferably, in one embodiment of the present invention, the semiconductor layer is titanium dioxide;

[0036] Preferably, in one embodiment of the present invention, the first conductive layer and the second conductive layer are FTO.

[0037] Preferably, in one embodiment of the present invention, the concentration of the material in the electrochromic layer may be 5 mg / mL, 10 mg / mL, 15 mg / mL, 20 mg / mL, or 30 mg / mL;

[0038] Preferably, in one embodiment of the present invention, the material concentration of the electrochromic layer is 10 mg / mL;

[0039] Preferably, in one embodiment of the present invention, the electrolyte layer comprises an electrolyte and a solvent. The electrolyte comprises one or more of lithium perchlorate, lithium chloride, and lithium bis(trifluoromethanesulfonyl)imide; the solvent comprises high-boiling-point solvents such as propylene carbonate, tetrahydrofuran, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, toluene, xylene, and ethyl acetate.

[0040] Preferably, in one embodiment of the present invention, the electrolyte is lithium chloride;

[0041] Preferably, in one embodiment of the present invention, the solvent is propylene carbonate;

[0042] Preferably, in one embodiment of the present invention, the concentration of the electrolyte is 0.1M.

[0043] Preferably, in one embodiment of the present invention, the preparation process includes: immersing an electrochromic material solution in a semiconductor layer for grafting for 24 hours, and filling an electrolyte layer between the semiconductor layer and the second conductive layer.

[0044] Preferably, in one embodiment of the present invention, the preparation process includes: coating a semiconductor layer onto a first conductive layer, and grafting an electrochromic layer onto the semiconductor layer;

[0045] Preferably, in one embodiment of the present invention, the preparation process includes: the electrochromic device includes a filling space defined between the semiconductor layer and the second conductive layer, and the method includes: filling the electrolyte layer into the filling space and sealing it to obtain the electrochromic device.

[0046] The present invention also provides an electrochromic device for use in smart windows, rearview mirrors or electronic devices.

[0047] The beneficial effects are as follows:

[0048] The electrochromic compounds provided by this invention use tetrapyridine as a basic framework. Benzene rings, thiophenes, pyrroles, furans, and their derivatives can be introduced into the pyridine to expand the conjugated structure and thus regulate the electrochemical properties of the material. Furthermore, an asymmetric structure containing anchoring groups is designed. These anchoring groups can modify the nanoelectrode, fixing the color-changing material to the electrode end, so that the color-changing rate is not affected by the material's own diffusion structure. Simultaneously, introducing unsaturated hydrocarbon structures on the other side can improve the material's solubility and further increase its conjugation degree. These compounds, as electrochromic materials, have advantages such as rich colors, fast color-changing speed, and long lifespan. Devices based on these materials have advantages such as rich color changes, high contrast, fast response speed, and long device lifespan. Attached Figure Description

[0049] Figure 1 A schematic diagram of the structure of an example electrochromic device according to this application is shown;

[0050] Figure 2 The cyclic voltammogram of one of the devices is shown;

[0051] Figure 3 The optical stability of the electrochromic device of one of the devices is shown at 600 nm, with color switching voltages of -1.5V, 5s, +1.5V, 5s, 1000 cycles. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0053] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0054] The synthesis of the target compound consists of four steps:

[0055] The first step is to synthesize compound a by reacting M, which contains a dibromine or chlorine-substituted compound, with 4-pyridineboronic acid. M can be a straight-chain bond, or a benzene ring, thiophene, pyrrole, thienothiophene, thiazothiazole, or their substituted derivatives.

[0056] The reaction equation is as follows:

[0057]

[0058] The second step involves synthesizing viologen compounds containing a single anchoring group by reacting compound a with at least one of a halophosphate ester, a carboxylic acid ester, or a methylsiloxane. R4 is one of a monosubstituted phosphate ester (-PO(OCH2CH3)2), a methylsiloxane (-Si(OCH3)3), or ethyl acetate (-COOCH2CH3). The reaction equation is as follows:

[0059]

[0060] The third step is to obtain a bilaterally substituted pyridine derivative, where R2 is an unsaturated alkenyl or alkynyl group. Alkenyl groups include vinyl (-CH=CH2) and allyl (-CH2CH=CH2); alkynyl groups include ethynyl (-C≡CH), propynyl (-CH2C≡CH), and 1-propynyl (-C≡C-CH3). The reaction equation is as follows:

[0061]

[0062] The fourth step is hydrolysis under acidic conditions, where R1 is one of the monosubstituted phosphoric acid (-PO(OH)2), silicic acid (-Si(OH)3), or carboxylic acid (-COOH). The reaction equation is as follows:

[0063]

[0064] Example 1

[0065] 2 mol of 4-4'-bipyridine was placed in a pear-shaped flask, followed by 50 mL of acetonitrile (ACN), and then 1 mol of diethyl 2-bromoethylphosphonate was slowly added. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the mixture was precipitated with ethyl acetate to obtain a monosubstituted viologen derivative. The first-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropylene, and 50 mL of ACN was added and stirred for 24 h. The acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60 °C for 12 h to obtain the second-step product. Finally, the second-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, and the filter cake was filtered and dried to obtain the final product. Its chemical structure is as follows:

[0066]

[0067] Its chemical structure is characterized as follows: 1 H NMR (400MHz, DMSO) δ9.08(dd,4H),8.96(dd,4H),5.29(d,2H),5.08(d,2H),4.80(s,2H),2.42(d,2H),1.55-1.48(m,5H)ppm.

[0068] Example 2

[0069] 1 mol of 2,5-dibromothiophene, 3 mol of 4-pyridineboronic acid, and 8 mol of potassium carbonate were added to a dry Schlenk flask. Then, under a nitrogen atmosphere, a mixed solvent of 1,4-dioxane, ethanol, and triethylamine was injected into the reaction flask in a volume ratio of 1:5:1. Finally, 10% (mol) of Pd(PPh3)4 was rapidly poured into the flask and stirred at 100°C for 24 h. After cooling to room temperature, the residue was washed with DCM, the filtrate was separated and extracted, the organic layers were combined, and poured into an Erlenmeyer flask containing anhydrous Na2SO4. The mixture was dried for 1 h, distilled under reduced pressure, and finally purified by silica gel column chromatography to obtain the first-step product, 2,5-di(pyridin-4-yl)thiophene. Next, 1 mol of 2,5-di(pyridin-4-yl)thiophene was added to 50 mL of acetonitrile (ACN), and then 0.5 mol of diethyl 2-bromoethylphosphonate was slowly added. The mixture was refluxed at 80°C for 24 h. After the reaction was complete, ethyl acetate was used to precipitate the monosubstituted second-step product. The obtained second-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropylene, followed by the addition of 50 mL of ACN and stirring for 24 h. Acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60°C for 12 h to obtain the third-step product. Finally, the third-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100°C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, which was then filtered and the filter cake dried to obtain the final product. Its chemical structure is as follows:

[0070]

[0071] Its chemical structure is characterized as follows: 1 H NMR (500MHz, Chloroform-d) δ8.91,8.78,7.79,7.60,7.40,6.00,5.93,5.25,5.22,5.21,5.19,4.95,4.93,4.86,4.83,4.63,3.39,3.36,3.31,3.28.

[0072] Example 3

[0073] 1 mol of 2,5-dibromo-3,4-bis(trifluoromethyl)thiophene, 3 mol of 4-pyridineboronic acid, and 8 mol of potassium carbonate were added to a dry Schlenk flask. Then, under a nitrogen atmosphere, a mixed solvent of 1,4-dioxane, ethanol, and triethylamine was injected into the reaction flask in a volume ratio of 1:5:1. Finally, 10% (mol) of Pd(PPh3)4 was rapidly poured into the flask and stirred at 100°C for 24 h. After cooling to room temperature, the residue was washed with DCM, the filtrate was separated and extracted, the organic layers were combined, and the mixture was poured into an Erlenmeyer flask containing anhydrous Na2SO4. The mixture was dried for 1 h, distilled under reduced pressure, and finally purified by silica gel column chromatography to obtain the first-step product, 4,4'-(3,4-bis(trifluoromethyl)thiophene-2,5-diyl)bipyridine. Next, 1 mol of 4,4'-(3,4-bis(trifluoromethyl)thiophene-2,5-diyl)bipyridine was added to 50 mL of acetonitrile (ACN), followed by the slow addition of 0.5 mol of diethyl 2-bromoethylphosphonate. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the product was precipitated with ethyl acetate to obtain the monosubstituted second-step product. The obtained second-step product was then added to a pear-shaped flask in an equimolar ratio with propargyl bromide, followed by the addition of 50 mL of ACN and stirring for 24 h. The acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60 °C for 12 h to obtain the third-step product. Finally, the third-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, and the filter cake was filtered and dried to obtain the final product. Its chemical structure is as follows:

[0074]

[0075] Its chemical structure is characterized as follows: 1 H NMR(500MHz,Chloroform-d)δ8.81(s,2H),8.76(s,2H),7.80(s,2H),7.65(s,2H ),5.93(s,2H),4.67(s,2H),4.63(s,2H),3.27(s,2H),2.94(s,2H),2.64(s,1H).

[0076] Example 4

[0077] 1 mol of 2,5-dibromo-thieno[3,2-b]thiophene, 3 mol of 4-pyridineboronic acid, and 8 mol of potassium carbonate were added to a dry Schlenk flask. Then, under a nitrogen atmosphere, a mixed solvent of 1,4-dioxane, ethanol, and triethylamine was injected into the reaction flask in a volume ratio of 1:5:1. Finally, 10% (mol) of Pd(PPh3)4 was rapidly poured into the flask and stirred at 100°C for 24 h. After cooling to room temperature, the residue was washed with DCM, the filtrate was separated and extracted, the organic layers were combined, and the mixture was poured into an Erlenmeyer flask containing anhydrous Na2SO4. The mixture was dried for 1 h, distilled under reduced pressure, and finally purified by silica gel column chromatography to obtain the first-step product, 2,5-bis(pyridin-4-yl)thieno[3,2-b]thiophene. Next, 1 mol of 2,5-bis(pyridin-4-yl)thiopheno[3,2-b]thiophene was added to 50 mL of acetonitrile (ACN), followed by the slow addition of 0.5 mol of (3-bromopropyl)trimethoxysilane. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the product was precipitated with ethyl acetate to obtain the monosubstituted second-step product. The obtained second-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropyl (Br-CH2C≡CH), and 50 mL of ACN was added and stirred for 24 h. The acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60 °C for 12 h to obtain the third-step product. Finally, the third-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, and the filter cake was dried to obtain the final product. Its chemical structure is as follows:

[0078]

[0079] Its chemical structure is characterized as follows:

[0080] 1 H NMR(500MHz,Chloroform-d)δ8.82(s,5H),7.73(s,2H),7.56(s,3H),7.49(s,2H),6.41(s,3H),5.04(d,J= 12.5Hz,1H),4.86(d,J=12.5Hz,1H),4.43(s,2H),2.89(s,1H),2.13–2.06(m,4H),2.01(d,J=12.3Hz,1H).

[0081] Example 5

[0082] 1 mol of 1,4-dibromobenzene, 3 mol of 4-pyridineboronic acid, and 8 mol of potassium carbonate were added to a dry Schlenk flask. Then, under a nitrogen atmosphere, a mixed solvent of 1,4-dioxane, ethanol, and triethylamine was injected into the reaction flask in a volume ratio of 1:5:1. Finally, 10% (mol) of Pd(PPh3)4 was rapidly poured into the flask and stirred at 100°C for 24 h. After cooling to room temperature, the residue was washed with DCM, the filtrate was separated and extracted, the organic layers were combined, and poured into an Erlenmeyer flask containing anhydrous Na2SO4. The mixture was dried for 1 h, distilled under reduced pressure, and finally purified by silica gel column chromatography to obtain the first-step product, 1,4-di(pyridin-4-yl)benzene. Next, 1 mol of 1,4-di(pyridin-4-yl)benzene was added to 50 mL of acetonitrile (ACN), and then 0.5 mol of ethyl 4-bromobutyrate was slowly added. The mixture was refluxed at 80°C for 24 h. After the reaction was complete, ethyl acetate was used to precipitate the monosubstituted second-step product. The obtained second-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropylene, followed by the addition of 50 mL of ACN and stirring for 24 h. Acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60°C for 12 h to obtain the third-step product. Finally, the third-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100°C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, which was then filtered and the filter cake dried to obtain the final product. Its chemical structure is as follows:

[0083]

[0084] Its chemical structure is characterized as follows: 1 H NMR(500MHz,Chloroform-d)δ9.01(s,2H),8.56(s,2H),7.74(d,J=7.5Hz,4H),7.66(s,4H),6.00(s,1H),5.22(s,2H),4 .94(d,J=12.5Hz,1H),4.84(d,J=12.5Hz,1H),4.65(s,2H),2.50(d,J=12.5Hz,1H),2.44(d,J=12.5Hz,1H),2.26(s,2H).

[0085] Example 6

[0086] 1 mol of 1,4-dibromo-2,5-bis(trifluoromethyl)benzene, 3 mol of 4-pyridineboronic acid, and 8 mol of potassium carbonate were added to a dry Schlenk flask. Then, under a nitrogen atmosphere, a mixed solvent of 1,4-dioxane, ethanol, and triethylamine was injected into the reaction flask in a volume ratio of 1:5:1. Finally, 10% (mol) of Pd(PPh3)4 was rapidly poured into the flask and stirred at 100°C for 24 h. After cooling to room temperature, the residue was washed with DCM, the filtrate was separated and extracted, the organic layers were combined, and the mixture was poured into an Erlenmeyer flask containing anhydrous Na2SO4. The mixture was dried for 1 h, distilled under reduced pressure, and finally purified by silica gel column chromatography to obtain the first-step product, 4,4'-(2,5-bis(trifluoromethyl)-1,4-phenylene)bipyridine. Next, 1 mol of 4,4'-(2,5-bis(trifluoromethyl)-1,4-phenylene)bipyridine was added to 50 mL of acetonitrile (ACN), followed by the slow addition of 0.5 mol of diethyl 2-bromoethylphosphonate. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the product was precipitated with ethyl acetate to obtain the monosubstituted second-step product. The obtained second-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropylene, followed by the addition of 50 mL of ACN and stirring for 24 h. The acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60 °C for 12 h to obtain the third-step product. Finally, the third-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, and the filter cake was filtered and dried to obtain the final product. Its chemical structure is as follows:

[0087]

[0088] Its chemical structure is characterized as follows: 1 H NMR(500MHz,Chloroform-d)δ8.81(s,2H),8.76(s,2H),7.78(s,2H),7.65(d,J=3.1Hz,4H),5.99(s,1H ),5.93(s,2H),5.19(s,2H),4.94(d,J=12.5Hz,1H),4.79(d,J=12.5Hz,1H),4.63(s,2H),3.27(s,2H).

[0089] Example 7

[0090] 1 mol of 1,4-dibromo-2,5-dimethoxybenzene, 3 mol of 4-pyridineboronic acid, and 8 mol of potassium carbonate were added to a dry Schlenk flask. Then, under a nitrogen atmosphere, a mixed solvent of 1,4-dioxane, ethanol, and triethylamine was injected into the reaction flask in a volume ratio of 1:5:1. Finally, 10% (mol) of Pd(PPh3)4 was rapidly poured into the flask and stirred at 100°C for 24 h. After cooling to room temperature, the residue was washed with DCM, the filtrate was separated and extracted, the organic layers were combined, and the mixture was poured into an Erlenmeyer flask containing anhydrous Na2SO4. The mixture was dried for 1 h, distilled under reduced pressure, and finally purified by silica gel column chromatography to obtain the first-step product, 4,4'-(2,5-dimethoxy-1,4-phenylene)bipyridine. Next, 1 mol of 4,4'-(2,5-dimethoxy-1,4-phenylene)bipyridine was added to 50 mL of acetonitrile (ACN), followed by the slow addition of 0.5 mol of diethyl 2-bromoethylphosphonate. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the product was precipitated with ethyl acetate to obtain the monosubstituted second-step product. The obtained second-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropylene, followed by the addition of 50 mL of ACN and stirring for 24 h. The acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60 °C for 12 h to obtain the third-step product. Finally, the third-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, and the filter cake was filtered and dried to obtain the final product. Its chemical structure is as follows:

[0091]

[0092] Its chemical structure is characterized as follows: 1 H NMR(500MHz,Chloroform-d)δ8.78(d,J=15.0Hz,5H),7.75(s,3H),7.62(s,3H),7.04(s,2H),6.00(s,1H),5.20(s,2H),4.94(d,J=12.5Hz,1H),4 .79(d,J=12.5Hz,1H),4.64(s,2H),3.87(s,6H),2.47(d,J=12.4Hz,1H) ,2.41(d,J=12.4Hz,1H),2.36(d,J=12.3Hz,1H),2.26(d,J=12.5Hz,1H).

[0093] Example 8

[0094] 1 mol of 5,7-dibromo-2,3-dihydrothieno[3,4-b][1,4]dioxin, 3 mol of 4-pyridineboronic acid, and 8 mol of potassium carbonate were added to a dry Schlenk flask. Then, under a nitrogen atmosphere, a mixed solvent of 1,4-dioxane, ethanol, and triethylamine was injected into the reaction flask in a volume ratio of 1:5:1. Finally, 10% (mol) of Pd(PPh3)4 was rapidly poured into the flask and stirred at 100°C for 24 h. After cooling to room temperature, the residue was washed with DCM, the filtrate was separated and extracted, the organic layers were combined, and the mixture was poured into an Erlenmeyer flask containing anhydrous Na2SO4. The mixture was dried for 1 h, distilled under reduced pressure, and finally purified by silica gel column chromatography to obtain the first-step product, 5,7-bis(pyridin-4-yl)-2,3-dihydrothieno[3,4-b][1,4]dioxin. Next, 1 mol of 5,7-bis(pyridin-4-yl)-2,3-dihydrothiophene[3,4-b][1,4]dioxin was added to 50 mL of acetonitrile (ACN), followed by the slow addition of 0.5 mol of diethyl 2-bromoethylphosphonate. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the product was precipitated with ethyl acetate to obtain the monosubstituted second-step product. The obtained second-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropylene, and 50 mL of ACN was added and stirred for 24 h. The acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum drying oven at 60 °C for 12 h to obtain the third-step product. Finally, the third-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, and the filter cake was filtered and dried to obtain the final product. Its chemical structure is as follows:

[0095]

[0096] Its chemical structure is characterized as follows: 1 H NMR(500MHz,Chloroform-d)δ8.99(s,2H),8.87(s,2H),7.56(s,2H),7.51(s,2H),6.12(s,2H),6.00(s,1H),5.19(s,2H),4.94(d,J= 12.5Hz,1H),4.79(d,J=12.5Hz,1H),4.63(s,2H),4.32(d,J=8.8Hz,3H),4.27(s,1H),3.43(d,J=12.5Hz,1H),3.32(d,J=12.3Hz,1H).

[0097] Example 9

[0098] 1 mol of 2,5-dibromo-1-phenyl-1H-pyrrole, 3 mol of 4-pyridineboronic acid, and 8 mol of potassium carbonate were added to a dry Schlenk flask. Then, under a nitrogen atmosphere, a mixed solvent of 1,4-dioxane, ethanol, and triethylamine was injected into the reaction flask in a volume ratio of 1:5:1. Finally, 10% (mol) of Pd(PPh3)4 was rapidly poured into the flask and stirred at 100°C for 24 h. After cooling to room temperature, the residue was washed with DCM, the filtrate was separated and extracted, the organic layers were combined, and the mixture was poured into an Erlenmeyer flask containing anhydrous Na2SO4. The mixture was dried for 1 h, distilled under reduced pressure, and finally purified by silica gel column chromatography to obtain the first-step product, 4,4'-(1-phenyl-1H-pyrrole-2,5-diyl)bipyridine. Next, 1 mol of 4,4'-(1-phenyl-1H-pyrrole-2,5-diyl)bipyridine was added to 50 mL of acetonitrile (ACN), followed by the slow addition of 0.5 mol of diethyl 2-bromoethylphosphonate. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the product was precipitated with ethyl acetate to obtain the monosubstituted second-step product. The obtained second-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropylene, followed by the addition of 50 mL of ACN and stirring for 24 h. The acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60 °C for 12 h to obtain the third-step product. Finally, the third-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, and the filter cake was filtered and dried to obtain the final product. Its chemical structure is as follows:

[0099]

[0100] Its chemical structure is characterized as follows: 1 H NMR(500MHz,Chloroform-d)δ8.87(s,2H),8.81(s,2H),7.94(s,2H),7.77(s,2H),7.54–7.34(m,8H),6.12(s,2H),6.00(s,1 H), 5.19 (s, 2H), 4.87 (d, J = 12.3Hz, 1H), 4.71 (d, J = 12.4Hz, 1H), 4.63 (s, 2H), 3.38 (d, J = 12.3Hz, 1H), 3.27 (d, J = 12.5Hz, 1H).

[0101] Example 10

[0102] 1 mol of 2,5-dibromo-1-(4-(trifluoromethoxy)benzyl)-1H-pyrrole, 3 mol of 4-pyridineboronic acid, and 8 mol of potassium carbonate were added to a dry Schlenk flask. Then, under a nitrogen atmosphere, a mixed solvent of 1,4-dioxane, ethanol, and triethylamine was injected into the reaction flask in a volume ratio of 1:5:1. Finally, 10% (mol) of Pd(PPh3)4 was rapidly poured into the flask and stirred at 100°C for 24 h. After cooling to room temperature, the residue was washed with DCM, the filtrate was separated and extracted, the organic layers were combined, and the mixture was poured into an Erlenmeyer flask containing anhydrous Na2SO4. The mixture was dried for 1 h, distilled under reduced pressure, and finally purified by silica gel column chromatography to obtain the first-step product, 4,4'-(1-(4-(trifluoromethoxy)benzyl)-1H-pyrrole-2,5-diyl)bipyridine. Next, 1 mol of 4,4'-(1-(4-(trifluoromethoxy)benzyl)-1H-pyrrole-2,5-diyl)bipyridine was added to 50 mL of acetonitrile (ACN), followed by the slow addition of 0.5 mol of diethyl 2-bromoethylphosphonate. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the product was precipitated with ethyl acetate to obtain the monosubstituted second-step product. The obtained second-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropylene, followed by the addition of 50 mL of ACN and stirring for 24 h. The acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum drying oven at 60 °C for 12 h to obtain the third-step product. Finally, the third-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, which was then filtered and dried to obtain the final product.

[0103] Its chemical structural formula is as follows

[0104]

[0105] Its chemical structure is characterized as follows: 1 H NMR(500MHz,Chloroform-d)δ8.82(s,2H),8.76(s,2H),7.77(d,J=7.5Hz,4H),7.44(s,2H),7.27–7.18(m,5H),5.97(s,1H),5.93(s,2H),5.49 (dt,J=12.3,1.0Hz,1H),5.39(dt,J=12.4,1.0Hz,1H),5.19(s,2H),4.94(d,J=12.3Hz,1H),4.79(d,J=12.5Hz,1H),4.64(s,2H),3.27(s,2H).

[0106] Example 11

[0107] 1 mol of 2,5-dibromofuran, 3 mol of 4-pyridineboronic acid, and 8 mol of potassium carbonate were added to a dry Schlenk flask. Then, under a nitrogen atmosphere, a mixed solvent of 1,4-dioxane, ethanol, and triethylamine was injected into the reaction flask, with a volume ratio of 1:5:1. Finally, 10% (mol) of Pd(PPh3)4 was rapidly poured into the flask and stirred at 100°C for 24 h. After cooling to room temperature, the residue was washed with DCM, the filtrate was separated and extracted, the organic layers were combined, and poured into an Erlenmeyer flask containing anhydrous Na2SO4. The mixture was dried for 1 h, distilled under reduced pressure, and finally purified by silica gel column chromatography to obtain the first-step product, 2,5-di(pyridin-4-yl)furan. Next, 1 mol of 2,5-di(pyridin-4-yl)furan was added to 50 mL of acetonitrile (ACN), and then 0.5 mol of diethyl 2-bromoethylphosphonate was slowly added. The mixture was refluxed at 80°C for 24 h. After the reaction was complete, ethyl acetate was used to precipitate the monosubstituted second-step product. The obtained second-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropylene, followed by the addition of 50 mL of ACN and stirring for 24 h. Acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60°C for 12 h to obtain the third-step product. Finally, the third-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100°C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, which was then filtered and the filter cake dried to obtain the final product. Its chemical structure is as follows:

[0108]

[0109] Its chemical structure is characterized as follows: 1 H NMR(500MHz,Chloroform-d)δ9.12(s,1H),9.00(s,1H),7.87(s,2H),7.16(s,1H),6 .00(s,0H),5.93(s,1H),5.22(s,1H),4.95(s,1H),4.63(s,1H),3.46–3.34(m,1H).

[0110] Example 12

[0111] 1 mol of 2,5-dibromothiazo[5,4-d]thiazole, 3 mol of 4-pyridineboronic acid, and 8 mol of potassium carbonate were added to a dry Schlenk flask. Then, under a nitrogen atmosphere, a mixed solvent of 1,4-dioxane, ethanol, and triethylamine was injected into the reaction flask in a volume ratio of 1:5:1. Finally, 10% (mol) of Pd(PPh3)4 was rapidly poured into the flask and stirred at 100°C for 24 h. After cooling to room temperature, the residue was washed with DCM, the filtrate was separated and extracted, the organic layers were combined, and the mixture was poured into an Erlenmeyer flask containing anhydrous Na2SO4. The mixture was dried for 1 h, distilled under reduced pressure, and finally purified by silica gel column chromatography to obtain the first-step product, 2,5-bis(pyridin-4-yl)thiazo[5,4-d]thiazole. Next, 1 mol of 2,5-bis(pyridin-4-yl)thiazo[5,4-d]thiazole was added to 50 mL of acetonitrile (ACN), followed by the slow addition of 0.5 mol of diethyl 2-bromoethylphosphonate. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the product was precipitated with ethyl acetate to obtain the monosubstituted second-step product. The obtained second-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropylene, and 50 mL of ACN was added and stirred for 24 h. The acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum drying oven at 60 °C for 12 h to obtain the third-step product. Finally, the third-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, and the filter cake was filtered and dried to obtain the final product. Its chemical structure is as follows:

[0112]

[0113] Its chemical structure is characterized as follows: 1 H NMR(500MHz,Chloroform-d)δ9.01(s,2H),8.85(s,2H),8.12(s,2H),8.01(s,2H),6.12(s,2H),6.00(s,1H),5.19( s,2H),4.94(d,J=12.5Hz,1H),4.79(d,J=12.5Hz,1H),4.63(s,2H),3.43(d,J=12.5Hz,1H),3.32(d,J=12.3Hz,1H).

[0114] Example 13

[0115] 1 mol of 2,5-dibromothiophene[3,2-b]thiophene, 3 mol of 4-pyridineboronic acid, and 8 mol of potassium carbonate were added to a dry Schlenk flask. Then, under a nitrogen atmosphere, a mixed solvent of 1,4-dioxane, ethanol, and triethylamine was injected into the reaction flask in a volume ratio of 1:5:1. Finally, 10% (mol) of Pd(PPh3)4 was rapidly poured into the flask and stirred at 100°C for 24 h. After cooling to room temperature, the residue was washed with DCM, the filtrate was separated and extracted, the organic layers were combined, and the mixture was poured into an Erlenmeyer flask containing anhydrous Na2SO4. The mixture was dried for 1 h, distilled under reduced pressure, and finally purified by silica gel column chromatography to obtain the first-step product, 2,5-bis(pyridin-4-yl)thieno[3,2-b]thiophene. Next, 1 mol of 2,5-bis(pyridin-4-yl)thiophene[3,2-b]thiophene was added to 50 mL of acetonitrile (ACN), followed by the slow addition of 0.5 mol of diethyl 2-bromoethylphosphonate. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the product was precipitated with ethyl acetate to obtain the monosubstituted second-step product. The obtained second-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropylene, and 50 mL of ACN was added and stirred for 24 h. The acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60 °C for 12 h to obtain the third-step product. Finally, the third-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, and the filter cake was filtered and dried to obtain the final product. Its chemical structure is as follows:

[0116]

[0117] Its chemical structure was characterized as follows: ¹H NMR (500MHz, Chloroform-d) δ 8.85 (s, 2H), 8.81 (s, 2H), 7.84 (s, 2H), 7.74 (s, 2H), 7.56 (s, 2H), 6.12 (s, 2H), 6.00 (s, 1H), 5.19 (s, 2H), 4.94 (d, J = 12.5Hz, 1H), 4.79 (d, J = 12.5Hz, 1H), 4.63 (s, 2H), 3.38 (d, J = 12.3Hz, 1H), 3.27 (d, J = 12.5Hz, 1H).

[0118] Comparative Example 1

[0119] 2 mol of 4-4'-bipyridine was placed in a pear-shaped flask, followed by 50 mL of acetonitrile (ACN), and then 1 mol of diethyl 2-bromoethylphosphonate was slowly added. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the mixture was precipitated with ethyl acetate to obtain a monosubstituted viologen derivative. The first-step product was then added to a pear-shaped flask in an equimolar ratio with bromopropane, and 50 mL of ACN was added and stirred for 24 h. The acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60 °C for 12 h to obtain the second-step product. Finally, the second-step product was placed in a pear-shaped flask, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid, and the filter cake was filtered and dried to obtain the final product. Its chemical structure is as follows:

[0120]

[0121] Its chemical structure is characterized as follows: 1 H NMR(500MHz,Chloroform-d)δ8.79(d,J=7.8Hz,5H),7.92(s,2H),7.72(s,2H), 6.04(s,2H),4.59(s,2H),4.34(s,2H),3.30(s,2H),1.97(s,2H),0.98(s,3H).

[0122] Comparative Example 2

[0123] 2 mol of 4-4'-bipyridine was placed in a pear-shaped flask, followed by 50 mL of acetonitrile (ACN). Then, 2 mol of diethyl 2-bromoethylphosphonate was slowly added. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60 °C for 12 h. Finally, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid. The filter cake was dried to obtain the final product. Its chemical structure is as follows:

[0124]

[0125] Its chemical structure is characterized as follows: 1 H NMR (500MHz, Chloroform-d) δ8.76(s,1H),7.85(s,1H),5.93(s,1H),4.63(s,1H),3.37(s,1H).

[0126] Comparative Example 3

[0127] 2 mol of 4-4'-bipyridine was placed in a pear-shaped flask, followed by 50 mL of acetonitrile (ACN). Then, 2 mol of diethyl 2-bromoethylphosphonic acid was slowly added. The mixture was refluxed at 80 °C for 24 h. After the reaction was complete, the acetonitrile was evaporated to dryness, dissolved in water, and extracted with dichloromethane. The solution was then evaporated to dryness and dried in a vacuum oven at 60 °C for 12 h. Finally, excess dilute hydrochloric acid was added, and the mixture was refluxed at 100 °C for 10 h. After the reaction was complete, ethanol was added to precipitate the solid. The filter cake was dried to obtain the final product. Its chemical structure is as follows:

[0128]

[0129] Its chemical structure is characterized as follows: 1 H NMR (500MHz, Chloroform-d) δ8.79(s,2H),7.89(s,2H),4.33(s,2H),1.97(s,2H),0.96(s,3H).

[0130] Results Examples

[0131] The cathode electrochromic materials synthesized in Examples 1-13 and Comparative Examples 1-3 were applied to electrochromic devices. It should be particularly noted that the cathode electrochromic materials synthesized in Examples 1-13 and Comparative Examples 1-3 are formed by chloride ion salt formation. Electrochromic materials formed by bromide ion, iodide ion, trifluoromethanesulfonate anion, perchlorate anion, and tetrafluoroborate anion salt formation have similar properties to chloride ion-based materials, which will not be elaborated upon here.

[0132] The specific fabrication method is as follows: TiO2 slurry is coated onto FTO, heated to 120°C at a rate of 10°C per minute, held for 30 minutes, and then annealed. TiO2 / FTO is immersed in viologen solutions of different concentrations for 12 hours, washed with deionized water and ethanol, and then dried in a vacuum oven at 60°C. The adsorbed viologen / TiO2 / FTO is then tightly bonded to another ITO plate with 3M double-sided adhesive tape around its edges, and an electrolyte is injected; preferably, the electrolyte is a 0.1M LiClO4 PC solution, and the TiO2 thickness is 3μm. The assembled electrochromic device is obtained, and its specific structure is as follows: Figure 1 As shown.

[0133] After the devices were assembled, we conducted a series of studies on the electrochromic devices based on the above embodiments, testing the transmittance at the characteristic peaks over time, thereby obtaining the coloring time (t) of 16 devices. coloring ) and fading time (t) bleaching The results are shown in Table 1.

[0134] Table 1

[0135]

[0136]

[0137] As shown in Table 1, different M structures affect the driving voltage of the device, which depends on the electronegativity of the M unit. If the M electrons have the ability to withdraw electrons, the HOMO-LUMO energy level can be lowered, thereby reducing the driving voltage. For example, Examples 1, 2, and 6 are electron-withdrawing units, and the driving voltage of the device is relatively low. In contrast, the methoxy group on the benzene ring in Example 7 is an electron-donating group, which can increase the driving voltage. In Example 9, the conjugation effect of phenylpyrrole makes the electron cloud distribution more uniform, thereby increasing the driving voltage. Secondly, the M group can affect the final color of the device. For example, Examples 8-10 are pink, and Example 1 is blue-violet. Furthermore, the coloring and fading time of the material is affected by the molecular weight and steric hindrance of the material. For example, Example 9 has the slowest color switching speed.

[0138] From the above examples, it can be concluded that the electrochromic device prepared by this invention has the characteristics of high contrast and rapid color switching. (See attached...) Figure 2 It can be seen that the cyclic voltammogram of the device is very stable, and the driving voltage required for color change is very low; from the attached... Figure 3 It can be seen that the device's color switching speed is about 1 second, the contrast is close to 70%, and the device can switch continuously 10,000 times without optical attenuation.

[0139] To demonstrate the characteristics of this embodiment, comparative embodiments were designed and synthesized. Comparative Embodiment 1 is an anchored structure containing a butyl group. Test results show that, due to the absence of an M-unit, the material has a uniform blue color, and due to the high steric hindrance of the alkyl group, the device's color change and fading rate is slower than that of the embodiment. Comparative Embodiment 2 is viologen containing bilateral anchoring groups; due to the absence of an M-unit, the material is blue. Furthermore, the device composed of this material exhibits a very slow color change and fading rate because the viologen with bilateral anchoring groups is tightly adsorbed onto the semiconductor layer, making ion insertion and extraction difficult. The device's stability during testing is lower than that of the embodiment because the electron cloud of the material is highly concentrated in the bipyridyl salt. Comparative Embodiment 3 is a structure without anchoring groups and alkynyl groups. Due to the absence of chemisorption between the device and the semiconductor, the color change and fading rate is limited by the diffusion of the material itself; therefore, the device exhibits the slowest color change and fading rate.

[0140] The electrochromic material prepared in this invention, through the introduction of unsaturated alkenynes, especially allyl and propargyl groups, cannot undergo free radical polymerization due to their structural characteristics. This also effectively expands the conjugated structure, reduces electron cloud density, and improves material stability. Secondly, the short alkenyne structure has low steric hindrance. After chemisorption with the semiconductor layer, the low steric hindrance at the other end of the color-changing material promotes ion insertion and extraction, thereby increasing the color switching speed of the electrochromic device. Furthermore, the unique anchoring structure and chemisorption with the semiconductor layer ensure that the color change and fading of the device are not limited by the diffusion of the material itself. These characteristics enable us to obtain high-performance electrochromic devices that surpass those based on traditional materials.

[0141] The primers listed above are only a partial representative; other electrochromic compounds containing the same concept are all within the scope of this patent protection.

[0142] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An electrochromic compound, characterized in that, Its structural formula is shown below: Among them, R1 is one of phosphate group -PO(OH)2, silica group -Si(OH)3 and acetic acid group -CH2COOH; M is a benzene substituted at position 2 and / or position 5 by any one of F, CF3, OCH3, or OCF3, or M is selected from benzene, 1,4-dibromo-2,5-bis(trifluoromethyl)benzene, thiophene, furan, phenylpyrrole, thienothiophene, 2,3-dihydrothieno[3,4-b][1,4]dioxin, or thiazothiazole; R2 is an alkenyl or alkynyl group; m and n are independent integers between 2 and 12; X - Selected from chloride ion, bromide ion, iodide ion, trifluoromethanesulfonate anion, perchlorate anion, and tetrafluoroborate anion.

2. The electrochromic compound according to claim 1, characterized in that, It has the structure shown in equations (B) to (F) as follows: 。 3. An electrochromic compound, characterized in that, It has any one of the structural formulas shown in equations (2) to (9): 。 4. A method for preparing the electrochromic compound according to any one of claims 1-2, characterized in that, Includes the following steps: Compound a reacts with compound b under reflux to obtain compound c, then compound c reacts with compound d under reflux in an organic solvent to obtain compound e, and finally acidification and hydrolysis are performed to obtain the final electrochromic compound. Wherein, M is benzene substituted at positions 2 and / or 5 by any one of F, CF3, OCH3, or OCF3, or M is selected from benzene, 1,4-dibromo-2,5-bis(trifluoromethyl)benzene, thiophene, furan, phenylpyrrole, thienothiophene, 2,3-dihydrothieno[3,4-b][1,4]dioxin, and thiazothiazole; The structural formula of compound b is R3-(CH2). m -R4, m is an integer between 2 and 12, R4 is any one of I, Br, and Cl, and R3 is one of monosubstituted phosphate ester -PO(OCH2CH3)2, methylsiloxane -Si(OCH3)3, and ethyl acetate -COOCH2CH3; The structural formula of compound d is R2-(CH2). n -R5, where n is an integer between 2 and 12, R2 is an alkenyl or alkynyl group, and R5 is any one of I, Br, or Cl.

5. The preparation method according to claim 4, characterized in that, m can be 2 or 3, and n can be 2 or 3.

6. The preparation method according to claim 4, characterized in that, The structural formula of compound b is one of the following: The structural formula of compound d is one of the following: 。 7. An electrochromic device, characterized in that, It includes a first conductive layer, a second conductive layer, a semiconductor layer, an electrochromic layer, and an electrolyte layer between the first conductive layer and the second conductive layer; the electrochromic layer uses the electrochromic compound according to any one of claims 1-3, or uses the electrochromic compound obtained by the preparation method according to any one of claims 4-6.

8. The application of the electrochromic device as described in claim 7 in smart windows, rearview mirrors, or electronic devices.

Images