Electrochromic compound capable of switching between purple system and transparent state and preparation method and application thereof
Thiophene-based compounds enable rapid and stable violet-to-transparent transitions, addressing the lack of soluble electrically switchable materials for decorative displays and anti-counterfeiting, with high optical contrast and cycle stability.
Patent Information
- Application Number
- CN202510467248.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-15
- Publication Date
- 2025-07-15
AI Technical Summary
The prior art lacks solution-processed electrochromic materials that can be switched in the purple-transparent state, and cannot meet the unique needs of the fields of decorative display and anti-counterfeiting labels.
The electrochromic compounds with a thiophene structure were prepared by arylation polycondensation reaction, and the compounds P-B, PH-B, and PC-B were sprayed on ITO glass to form a film to achieve the switching of purple-transparent state.
It realizes reversible switching of purple-transparent state, has high optical contrast and good cycle stability, and is suitable for electronic price tag fields.
Smart Images
Figure CN120309900A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of chemical materials, and particularly relates to electrochromic compounds that can switch between the purple-transparent states, their preparation methods and applications, as well as electrochromic films that can switch between the purple-transparent states. Background Art
[0002] Electrochromic materials are a type of functional materials that can reversibly change their optical properties (such as color, light transmittance, etc.) under the action of an external electric field, and have broad application prospects in fields such as smart windows, anti-glare rearview mirrors, and display devices. According to different chemical compositions, electrochromic materials can be divided into inorganic materials (such as WO3, NiO, etc.) and organic materials (such as viologens, conductive polymers, etc.). Among them, organic electrochromic materials have become a research hotspot in recent years due to their strong molecular structure designability, rich colors, fast response speed, and other advantages.
[0003] Among organic electrochromic materials, solution-processable electrochromic materials have received extensive attention because they can be prepared in large areas through low-cost and high-efficiency film-forming processes such as spraying. Currently, the solution-processable electrochromic material system based on the red-transparent state switch has been relatively mature. For example, materials based on viologen derivatives or specific conjugated polymers have achieved high contrast and cycle stability. However, the research on solution-processable electrochromic materials that can switch between the purple-transparent states is still relatively scarce. As an important spectral color, purple has unique requirements in fields such as decorative displays and anti-counterfeiting labels. Therefore, it is necessary to develop an electrochromic compound that can switch between the purple-transparent states and has good performance for preparing electrochromic materials that can switch between purple and transparent. Summary of the Invention
[0004] In order to solve the problem that the existing technology lacks solution-processable electrochromic materials that can switch between the purple-transparent states, the present invention provides three solution-processable electrochromic compounds that can switch between the purple-transparent states and have excellent optical and electrochromic properties, their preparation methods and applications, as well as electrochromic films that can switch between the purple-transparent states.
[0005] The technical solution adopted by the present invention is: an electrochromic compound that can switch between the purple-transparent states, the compound has a thiophene structure, and the compound is any one of the compounds shown in Formula I, Formula II, and Formula III:
[0006] Briefly denoted as compound P-B;
[0007] Briefly denoted as compound PH-B;
[0008] Briefly denoted as compound PC-B.
[0009] The present invention also provides a preparation method of the electrochromic compound, comprising: preparing the electrochromic compound by an arylation polycondensation reaction of a thiophene derivative and 2,5-dibromopyrazine (Formula V);
[0010]
[0011] The thiophene derivative is any one of the compounds shown in Formula IV, Formula VI, and Formula VII;
[0012] 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine;
[0013] 3,3-bis(((2-hexyldecyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine;
[0014] (3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepinoheptene-3,3-diyl)bis(methylene)bis(2-butyl octanoate).
[0015] Preferably, the preparation method comprises: under the protection of an inert gas, mixing the thiophene derivative, 2,5-dibromopyrazine, potassium carbonate, pivalic acid, Pd(OAc)2, and anhydrous DMAc, reacting at 120-140 °C for 15-17 h, and subjecting the reaction solution to post-treatment to obtain the electrochromic compound.
[0016] Preferably, the molar ratio of 2,5-dibromopyrazine to the thiophene derivative is 1-1.1:1, preferably 1:1.
[0017] Preferably, the molar ratio of potassium carbonate to the thiophene derivative is 2-3:1, preferably 2.5:1.
[0018] Preferably, the molar ratio of pivalic acid to the thiophene derivative is 0.01-0.1:1, preferably 0.04:1.
[0019] Preferably, the molar ratio of Pd(OAc)2 to the thiophene derivative is 0.01-0.05:1, preferably 0.02:1.
[0020] Preferably, the added volume of the anhydrous DMAc is 20-40 mL / g based on the mass of the thiophene derivative, preferably 20-35 mL / g.
[0021] Preferably, the post-treatment method is: adding the reaction solution to methanol, filtering, washing the filter cake with methanol, extracting the product from the filter cake using methanol, acetone, petroleum ether, and chloroform in sequence, and rotary evaporating the product extracted with chloroform to remove the solvent to obtain the electrochromic compound.
[0022] The present invention also provides the use of the electrochromic compound in preparing an electrochromic film that can switch between a purple series and a transparent state. The use comprises: dissolving the electrochromic compound in an organic solvent (preferably chloroform), and then spraying the electrochromic compound on the conductive surface of ITO glass to form a film, so as to prepare an electrochromic film that can switch between a purple series and a transparent state.
[0023] The present invention also provides an electrochromic film that can switch between a purple-transparent state. The electrochromic film is prepared by the following method: the electrochromic compound is dissolved in an organic solvent, and then sprayed on the conductive surface of ITO glass to form a film, so as to obtain the electrochromic film that can switch between a purple-transparent state.
[0024] Beneficial effects of the present invention: The present invention provides three electrochromic compounds based on thiophene structure that can switch between two colors. All of them show purple in the neutral state. As the applied voltage increases, the color finally shows a transparent state. Among them, the optical contrast of compound PB (Formula I) in the wavelength range of 560nm is 33.42%, the coloring time is 1.34s, and the fading time is 1.17s; the optical contrast of compound PH-B (Formula II) in the wavelength range of 540nm is 48.32%, the coloring time is 0.84s, and the fading time is 0.65s; the optical contrast of compound PC-B (Formula III) in the wavelength range of 560nm is 22.37%, the coloring time is 1.24s, and the fading time is 1.82s. After 1000 cycles at step voltages of 0V and 1.2V, the optical contrast of the electrochromic films made of PB, PH-B or PC-B can maintain 88.45%, 78.91% and 45.86% of the initial contrast. They are a class of solution-processable electrochromic materials with excellent performance that can switch between purple and transparent colors, and are expected to be used in the field of electronic price tags. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 The invention provides three synthetic routes of electrochromic materials that can switch between a purple series and a transparent state.
[0026] Figure 2 CV curves of three electrochromic films switchable between the purple series and transparent states provided in Example 4 of the present invention.
[0027] Figure 3UV-Vis absorption spectra of three electrochromic films that can switch between purple and transparent states provided in Example 4 of the present invention at different voltages.
[0028] Figure 4 Response times of three electrochromic films that can switch between purple and transparent states provided in Example 4 of the present invention at different wavelengths.
[0029] Figure 5 Kinetic tests of three electrochromic films that can switch between purple and transparent states provided in Example 4 of the present invention at different wavelengths.
[0030] Figure 6 Chromaticities of three electrochromic films that can switch between purple and transparent states provided in Example 4 of the present invention at different voltages. Detailed implementation manners
[0031] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. In the embodiments of the present invention, unless otherwise specified, the methods used are conventional methods, and the reagents used can be obtained from commercial channels.
[0032] Synthesis of Compound P-B (Formula I) in Example 1
[0033] Weigh 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine (Formula IV) (440.68 mg, 1.0 mmol), 2,5-dibromopyrazine (237.88 mg, 1.0 mmol), anhydrous potassium carbonate (345 mg, 2.5 mmol), pivalic acid (4.09 mg, 0.04 mmol) and Pd(OAc)2 (4.53 mg, 0.02 mmol) and add them into a 15 mL Schlenk tube. Under nitrogen protection, add 15 mL of anhydrous DMAc and react at 130 °C for 15 h, then cool to room temperature. Add the reaction solution into 300 ml of methanol, filter it with a Buchner funnel, and wash the filter cake with methanol. Wrap the filter cake with filter paper and extract polymers with different polymerization degrees in it using a Soxhlet extractor. During this process, change solvents with different dissolution abilities. The order of solvent use is methanol, acetone, petroleum ether, chloroform. Finally, rotary evaporate the chloroform-extracted part to remove the solvent and obtain Compound P-B (Formula I).
[0034] Synthesis of Compound PH-B (Formula II) in Example 2
[0035] Weigh 3,3-bis(((2-hexyldecyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine (Compound VI) (665.11 mg, 1 mmol), 2,5-dibromopyrazine (237.88 mg, 1.0 mmol), anhydrous potassium carbonate (345 mg, 2.5 mmol), pivalic acid (4.09 mg, 0.04 mmol) and Pd(OAc)2 (4.53 mg, 0.02 mmol) and add them into a 15 mL Schlenk tube. Under nitrogen protection, add 15 mL of anhydrous DMAc and react at 130 °C for 16 h, then cool to room temperature. Add the reaction solution to 300 ml of methanol, filter it with a Buchner funnel, and wash the filter cake with methanol. Wrap the filter cake with filter paper and extract the polymers with different degrees of polymerization using a Soxhlet extractor. During this process, change the solvents with different dissolution abilities. The order of solvent use is methanol, acetone, petroleum ether, chloroform. Finally, rotary evaporate the chloroform-extracted part to remove the solvent to obtain Compound PH-B (Formula II).
[0036] Synthesis of Compound PC-B (Formula III) in Example 3
[0037] Weigh (3,4-dihydro-2H-thieno[3,4-b][1,4]dioxoleno[3,4-g]cycloheptene-3,3-diyl)bis(methylene)bis(2-butyl octanoate) (Compound VII) (580.41 mg, 1 mmol), 2,5-dibromopyrazine (237.88 mg, 1.0 mmol), anhydrous potassium carbonate (345 mg, 2.5 mmol), pivalic acid (4.09 mg, 0.04 mmol) and Pd(OAc)2 (4.53 mg, 0.02 mmol) and add them into a 15 mL Schlenk tube. Under nitrogen protection, add 15 mL of anhydrous DMAc and react at 130 °C for 16 h, then cool to room temperature. Add the reaction solution to 300 ml of methanol, filter it with a Buchner funnel, and wash the filter cake with methanol. Wrap the filter cake with filter paper and extract the polymers with different degrees of polymerization using a Soxhlet extractor. During this process, change the solvents with different dissolution abilities. The order of solvent use is methanol, acetone, petroleum ether, chloroform. Finally, rotary evaporate the chloroform-extracted part to remove the solvent to obtain Compound PC-B (Formula III).
[0038] Preparation of Three Electrochromic Films in Example 4
[0039] 45 mg of the compounds P-B, PH-B, and PC-B prepared in Examples 1 to 3 were respectively added into 10-ml beakers. 3 ml of chloroform was added to each of them, and the solutions were shaken to mix evenly. Then, they were filtered using a microporous filter with a pore size of 0.45 μm. Subsequently, they were spin-coated onto the conductive surface of 25*40 mm ITO glass using a spin coater (parameter settings: 1000 rpm / min, spin coating time 1 min) to obtain electrochromic films.
[0040]
Performance Testing of Electrochromic Films
[0041] The electrochromic films respectively prepared from the compounds P-B, PH-B, and PC-B in Example 4 were tested as follows.
[0042] 1. Electrochemical Testing
[0043] Electrochemical testing was carried out using a Chenhua 660 electrochemical workstation. Parameter settings: CV mode, scan rates of 50 mv / s, 100 mv / s, 200 mv / s, 300 mv / s, and 500 mv / s, and scanning range of 1.2 V and 0 V. As Figure 2 shown, the electrochromic films respectively prepared from P-B, PH-B, and PC-B all had electrochemical responses within this scanning range, and their CV curves showed quasi-reversible redox behavior.
[0044] 2. Optical and Electrochromic Performance Testing
[0045] Optical and electrochromic performance testing was carried out using a combination of a Chenhua 660 electrochemical workstation and a Shimadzu UV1800 ultraviolet-visible spectrophotometer. The test results are as Figure 3 、 4 、5 shown.
[0046] As Figure 3 shown, the maximum absorption peaks of the three films in the neutral state (0.0 V) were 560 nm, 540 nm, and 560 nm; as the voltage increased continuously, the original absorption peaks gradually disappeared, and a double-absorption characteristic appeared in the visible light region (the trough of the absorption curve appeared between 500 and 600 nm); as the voltage was further increased, there were no obvious absorption peaks in the absorption curves of the three films in the visible light region.
[0047] As Figure 4 and Figure 5As shown, the optical contrast and cycling stability of three kinds of thin films were respectively tested in the band of the maximum absorption peak. It was found that the optical contrast of P-B was 33.42% in the wavelength range of 560 nm, the coloring time was 1.34 s, and the fading time was 1.17 s; the optical contrast of PH-B was 48.32% in the wavelength range of 540 nm, the coloring time was 0.84 s, and the fading time was 0.65 s; the optical contrast of PC-B was 22.37% in the wavelength range of 560 nm, the coloring time was 1.24 s, and the fading time was 1.82 s; after 1000 cycles under the step voltage of 0 V and 1.2 V, the optical contrasts of the three materials could maintain 88.45%, 78.91% and 45.86% of the initial contrast.
[0048] 3. Chromaticity test
[0049] As Figure 6 shown, at 0 V, all three kinds of thin films presented purple, and with the continuous increase of the voltage, the three kinds of thin films finally presented a transparent state.
[0050] The embodiments described above are only used to describe the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope of the present invention.
Claims
1. An electrochromic compound that can be switched between a purple color system and a transparent state, characterized in that, The compound has a thiophene structure, and the compound is any one of the compounds represented by Formula I, Formula II, and Formula III:
2. The preparation method of the electrochromic compound according to claim 1, characterized in that, Including: The electrochromic compound is prepared by the arylation polycondensation reaction of a thiophene derivative and 2,5-dibromopyrazine; The thiophene derivative is any one of the compounds represented by Formula IV, Formula VI, and Formula VII; 3. The method according to claim 2, wherein Including: Under the protection of an inert gas, the thiophene derivative, 2,5-dibromopyrazine, potassium carbonate, pivalic acid, Pd(OAc)2, and anhydrous DMAc are mixed and reacted at 120-140 °C for 15-17 h. The reaction solution is post-treated to obtain the electrochromic compound.
4. The method according to claim 3, wherein The molar ratio of 2,5-dibromopyrazine to the thiophene derivative is 1-1.1:
1.
5. The method according to claim 3, wherein The molar ratio of potassium carbonate to the thiophene derivative is 2-3:
1.
6. The method according to claim 3, characterized in that, The molar ratio of pivalic acid to the thiophene derivative is 0.01-0.1:
1.
9. The method according to claim 3, wherein The molar ratio of Pd(OAc)2 to the thiophene derivative is 0.01-0.05:1; and / or The added volume of the anhydrous DMAc is 20-40 mL / g based on the mass of the thiophene derivative.
8. The method according to claim 3, characterized in that The post-treatment method is: adding the reaction solution into methanol, filtering by suction, washing the filter cake with methanol, extracting the product from the filter cake successively with methanol, acetone, petroleum ether, and chloroform, and rotary evaporating the solvent from the product extracted by chloroform to obtain the electrochromic compound.
9. Use of the electrochromic compound according to claim 1 or the electrochromic compound prepared by the method according to any one of claims 2-8 in the preparation of an electrochromic film capable of switching between a purple system and a transparent state.
10. An electrochromic film capable of switching between a purple system - transparent state, characterized in that, The electrochromic film is prepared by the following method: dissolving the electrochromic compound according to claim 1 or the electrochromic compound prepared by the method according to any one of claims 2-8 in an organic solvent, and then spraying and forming a film on the conductive surface of ITO glass to obtain an electrochromic film capable of switching between a purple system and a transparent state.