Tetraphenylpyridine derivatives for electrochromic materials, methods of making, and uses thereof

Abstract

Some embodiments disclose tetraphenylpyridine derivatives for use in electrochromic materials, including compounds represented by the following general formula or salts thereof: Wherein, X is any one of F, Cl, and Br, and Y is ethyl or n-hexyl; electrochromic materials are prepared using compounds represented by the general formula; the obtained electrochromic materials include the compound represented by the general formula, ferrocene, poly(vinylidene fluoride-hexafluoropropylene), and an ionic liquid, with a molar ratio of 4:1:15:60; the ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine or 1-ethyl-3-methylimidazolium tetrafluoroborate. The introduction of heavy atoms F, Cl, and Br into the tetraphenylpyridine structure effectively increases the light absorption capacity and enhances the significance of the color change. The thin-layer structure of this tetraphenylpyridine derivative exhibits excellent light transmittance and provides structural stability and durability of the electrochromic material during the electrochromic process.

Description

Tetraphenylpyridine derivatives for electrochromic materials, their preparation methods, and applications Technical Field

[0001] This invention belongs to the field of electrochromic materials technology, specifically relating to tetraphenylpyridine derivatives used in electrochromic materials, their preparation methods, and applications. Background Technology

[0002] With the development of modern architecture and the automotive industry, the demand for intelligent dimming windows is increasing. Intelligent dimming windows can automatically adjust their transparency according to external light conditions, thereby improving energy efficiency, protecting privacy, and enhancing indoor comfort.

[0003] Currently, smart dimming window technology primarily relies on electrochromic (EC) materials. Traditional EC materials mainly include inorganic and organic materials. These materials are widely used in smart dimming windows, rearview mirrors, displays, and other fields. Inorganic materials typically possess excellent stability and durability, but their response speed is slow, and their preparation process is complex and costly. Organic materials offer advantages such as fast response speed, rich color changes, and simple preparation processes, but their cycle life and optical contrast are generally lower.

[0004] A typical EC (external color change) material consists of an active layer, an ion-conducting layer, and an electrode layer. The active layer is the key component for achieving color change; under an applied voltage, an electrochemical reaction causes redox reactions in the material, resulting in a color change. The ion-conducting layer provides the ion conduction pathway, while the electrode layer is used to apply voltage and transmit current. The performance of EC materials is mainly evaluated using the following metrics: optical contrast ratio (the difference in transmittance of the material under different voltages); response time (the time required for the material to transition from one color state to another); cycle life (the performance stability of the material after multiple cycles of use); and transmittance (the light transmittance of the material in its transparent state).

[0005] In summary, although existing electrochromic materials have achieved some applications in fields such as smart dimming windows, there are still some problems that urgently need to be solved. Inorganic materials have a slow color change response speed, making it difficult to meet the needs of rapid dimming, while organic materials have a short cycle life and will experience performance degradation after long-term use; some materials do not show significant differences in transmittance under different voltages, resulting in low optical contrast and affecting the dimming effect; the preparation process of some inorganic materials is complex and costly, limiting their large-scale application. For example, patent CN106959564A discloses a window glass with electrochromic properties, the structure of which consists of two transparent conductive glass layers with an electrochromic liquid sandwiched in between, and sealed with a polymer adhesive. The conductive layer is glass with a thin film of indium tin oxide, polythiophene, etc. on the surface, and the electrochromic liquid uses bipyridine salt compounds as cathodic color-changing materials and ferrocene or phenazine compounds as anodic color-changing materials. This invention has a simple process, low cost, and is suitable for window glass in smart buildings and transportation vehicles. However, it has the following shortcomings:

[0006] The molar absorptivity of bipyridine salts and ferrocene or phenazine compounds may have certain limitations in different wavelength ranges, and may exhibit low light absorption at certain wavelengths in the visible light range, resulting in insufficient or uneven color changes, thus affecting the overall visual effect and performance of electrochromic window glass.

[0007] The molecular structures of bipyridine salts and ferrocene or phenazine compounds may have a certain degree of non-planarity, which leads to a decrease in intermolecular stacking efficiency, thereby affecting electrochromic performance, resulting in a slower color change rate, reduced contrast, and shortened cycle life. Summary of the Invention

[0008] In view of this, some embodiments disclose tetraphenylpyridine derivatives for use in electrochromic materials, comprising a compound represented by general formula (I) below, or a hexafluorophosphate of the compound represented by general formula (I):

[0009]

[0010] Where X is any one of F, Cl, or Br, and Y is ethyl or n-hexyl.

[0011] On the other hand, some embodiments disclose methods for preparing tetraphenylpyridine derivatives for electrochromic materials, including:

[0012] The compound represented by general formula (II) reacts with a bromoalkane to give the compound represented by general formula (I);

[0013] The general formula (II) is:

[0014]

[0015] Wherein, X is any one of F, Cl, and Br, and the bromoalkane is bromomethane or 1-bromohexane.

[0016] On the other hand, some embodiments disclose the application of tetraphenylpyridine derivatives for electrochromic materials, using compounds represented by general formula (I) to prepare electrochromic materials.

[0017] This invention discloses a method for preparing a tetraphenylpyridine derivative for electrochromic materials. The prepared tetraphenylpyridine derivative introduces heavy atoms F, Cl, and Br into the tetraphenylpyridine structure, effectively increasing light absorption and enhancing the significance of color changes. The thin-layer structure of this tetraphenylpyridine derivative exhibits excellent light transmittance, while also providing structural stability and durability of the electrochromic material during the electrochromic process. The tetraphenylpyridine derivative exhibits significant color changes under different DC voltages, and these color changes can be identified and distinguished using the RGB color model, enabling rapid and accurate adjustment of light transmittance in practical applications. The electrochromic response is fast, with the material completing color conversion in a short time, resulting in high color contrast and ensuring significant visual differences under different states. Furthermore, the long cycle life improves the practicality and reliability of the electrochromic material. Detailed Implementation

[0018] The term "embodiment" used herein, as an example, is not necessarily to be construed as superior to or better than other embodiments. Performance testing in these embodiments of the invention, unless otherwise specified, employs conventional testing methods in the art. It should be understood that the terminology used in these embodiments is merely for describing particular implementations and is not intended to limit the scope of the disclosure of these embodiments.

[0019] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this invention pertain; other experimental methods and technical means not specifically noted in the embodiments of this invention refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0020] The terms “basic” and “approximately” used in this document are to describe small fluctuations. For example, they can mean less than or equal to ±5%, such as less than or equal to ±2%, such as less than or equal to ±1%, such as less than or equal to ±0.5%, such as less than or equal to ±0.2%, such as less than or equal to ±0.1%, such as less than or equal to ±0.05%. Numerical data presented or expressed in range format in this document are used for convenience and brevity only, and should therefore be flexibly interpreted to include not only the explicitly listed values ​​that define the range, but also all independent values ​​or subranges contained within that range. For example, a numerical range of “1–5%” should be interpreted to include not only the explicitly listed values ​​from 1% to 5%, but also the independent values ​​and subranges within the indicated range. Thus, this numerical range includes independent values ​​such as 2%, 3.5%, and 4%, and subranges such as 1%–3%, 2%–4%, and 3%–5%, etc. This principle also applies to ranges that list only one value. Furthermore, this interpretation applies regardless of the width of the range or the characteristics described.

[0021] In this document, including in the claims, conjunctions such as "comprising," "including," "with," "having," "containing," "involving," and "accommodating" are understood to be open-ended, meaning "including but not limited to." Only the conjunctions "consisting of" and "composed of" are closed conjunctions.

[0022] To better illustrate the content of this invention, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that the invention can be practiced even without certain specific details. In the embodiments, some methods, means, instruments, and devices well-known to those skilled in the art are not described in detail, in order to highlight the main points of the invention.

[0023] Without conflict, the technical features disclosed in the embodiments of the present invention can be combined arbitrarily, and the resulting technical solution belongs to the content disclosed in the embodiments of the present invention.

[0024] Some embodiments disclose tetraphenylpyridine derivatives for use in electrochromic materials, comprising compounds represented by the following general formula (I):

[0025]

[0026] Where X is any one of F, Cl, or Br, and Y is ethyl or n-hexyl.

[0027] Some embodiments disclose tetraphenylpyridine derivatives for electrochromic materials, where X is F, Y is ethyl in general formula (I), and the compound is 3,3'-difluoro-1,1'-diethyl-[4,4'-bipyridine]-1,1'-diimide.

[0028] Some embodiments disclose tetraphenylpyridine derivatives for use in electrochromic materials, where X in general formula (I) is Cl and Y is ethyl. The compound is 3,3'-dichloro-1,1'-diethyl-[4,4'-bipyridine]-1,1'-diimide.

[0029] Some embodiments disclose tetraphenylpyridine derivatives for use in electrochromic materials, where X is Br, Y is ethyl, and the compound is 3,3'-dibromo-1,1'-diethyl-[4,4'-bipyridine]-1,1'-diimide.

[0030] Some embodiments disclose tetraphenylpyridine derivatives for electrochromic materials, where X is F, Y is hexyl in general formula (I), and the compound is 3,3'-difluoro-1,1'-dihexyl-[4,4'-bipyridine]-1,1'-diimide.

[0031] Some embodiments disclose tetraphenylpyridine derivatives for use in electrochromic materials, where X in general formula (I) is Cl, Y is hexyl, and the compound is 3,3'-dichloro-1,1'-dihexyl-[4,4'-bipyridine]-1,1'-diimide.

[0032] Some embodiments disclose tetraphenylpyridine derivatives for use in electrochromic materials, where X in general formula (I) is Br, Y is hexyl, and the compound is 3,3'-dibromo-1,1'-dihexyl-[4,4'-bipyridine]-1,1'-diimide.

[0033] Some embodiments disclose methods for preparing tetraphenylpyridine derivatives for electrochromic materials, including:

[0034] The compound represented by general formula (II) is dissolved in a solvent with a bromoalkane, refluxed at 80°C, and reacted for 24 hours. After the reaction is complete, a pale yellow solid precipitates to obtain the compound represented by general formula (I). Acetonitrile or dichloromethane can be used as solvents. Dichloromethane is the preferred solvent. Using dichloromethane can improve solubility and reaction efficiency, reduce energy consumption and reaction time, and at the same time, room temperature operation is safer and reduces the risk of high temperature operation.

[0035] The general formula (II) is:

[0036]

[0037] Where X is any one of F, Cl, or Br, and the bromoalkane is bromomethane or 1-bromohexane;

[0038] The compound represented by general formula (I) was purified by recrystallization with ethanol;

[0039] The recrystallization product was dissolved in deionized water and heated to 60°C to dissolve it. After the ammonium hexafluorophosphate was fully dissolved in deionized water, it was slowly added dropwise. The hexafluorophosphate ions and bromide ions underwent an exchange reaction, replacing the bromide ions in the structure of the compound of general formula (I) to obtain the hexafluorophosphate of the compound of general formula (I).

[0040] As an optional embodiment, the recrystallized product was dissolved in deionized water and heated to 40°C to dissolve it. Ammonium hexafluorophosphate was then fully dissolved in deionized water and slowly added dropwise to carry out an ion exchange reaction, replacing the bromide ion in the structure of the compound of general formula (I). The addition was stopped once the system no longer became turbid. The mixture was then heated to 60°C and stirred for 2 hours before filtration to obtain the hexafluorophosphate of the compound shown in general formula (I). By lowering the heating temperature during the ion exchange process, the risk of possible decomposition can be reduced, while increasing the stirring time ensures the reaction proceeds completely, improving product purity and stability, and ensuring efficient product formation.

[0041] Some embodiments disclose the application of tetraphenylpyridine derivatives in electrochromic materials, using compounds of general formula (I) to prepare electrochromic materials; the electrochromic materials comprise the compound of general formula (I) or its hexafluorophosphate, ferrocene, poly(vinylidene fluoride-hexafluoropropylene), and an ionic liquid in a molar ratio of 4:1:15:60; the ionic liquid is 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine or 1-ethyl-3-methylimidazolium tetrafluoroborate. Typically, the compound of general formula (I), ferrocene, poly(vinylidene fluoride-hexafluoropropylene), and the ionic liquid are dissolved in acetone solution in a predetermined molar ratio to obtain an electrochromic solution.

[0042] Furthermore, the electrochromic solution was cast onto a glass slide to obtain a uniform, freestanding EC gel.

[0043] To fabricate the electrochromic device ECD, we cut the EC gel into the desired shape using a razor blade and transferred it to the target location. Then, the gel was sandwiched between another substrate with an ITO coating and securely fixed with double-sided tape to obtain the electrochromic device ECD. The color development effect and operational stability were analyzed by applying different DC voltages to the ECD. The ITO coating was a tin-doped indium oxide coating.

[0044] Typically, tetraphenylpyridine derivative electrochromic materials can be applied to smart dimming windows, automatically adjusting transparency according to external light conditions and user needs. High response speed and optical contrast ensure users can quickly obtain the desired dimming effect, improving the comfort of living and working environments; by regulating the light and heat entering the room, it can effectively reduce energy consumption for air conditioning and lighting, contributing to improved building energy efficiency.

[0045] Tetraphenylpyridine derivative electrochromic materials can also be used in other optical adjustment devices, such as rearview mirrors, displays, and goggles. Their rapid response and excellent light transmittance make them outstanding in these applications.

[0046] The technical details are further illustrated below with reference to the embodiments.

[0047] Example 1

[0048] Preparation of compound 1,1'-diethyl-3,3'-difluoro-[4,4'-bipyridine]-1,1'-diimide

[0049] The basic reaction is:

[0050]

[0051] The preparation method includes the following steps:

[0052] ① First, weigh 1g of 3,3'-difluoro-4,4'-bipyridine and 5g of bromoethane into a beaker, add acetonitrile to dissolve, reflux at 80℃, and react for 24h. After the reaction is complete and a pale yellow solid precipitates, filter and dry to obtain a pale yellow solid 1,1'-diethyl-3,3'-difluoro-[4,4'-bipyridine]-1,1'-diimine;

[0053] ②Then, the obtained pale yellow solid was purified by recrystallization with ethanol;

[0054] ③ Ideally, the purified product is dissolved in deionized water and heated to 60°C. After fully dissolving ammonium hexafluorophosphate in water, it is slowly added dropwise to the reaction. Once the system no longer produces turbidity, the addition is stopped. After stirring for 1 hour, the mixture is filtered and dried to obtain the hexafluorophosphate of the compound: hexafluorophosphate-1,1'-diethyl-3,3'-difluoro-[4,4'-bipyridine]-1,1'-diimine.

[0055] Example 2

[0056] Preparation of compound 3,3'-dichloro-1,1'-diethyl-[4,4'-bipyridine]-1,1'-diimide

[0057] The basic reaction is:

[0058]

[0059] The preparation method includes the following steps:

[0060] ① First, weigh 1g of 3,3'-dichloro-4,4'-bipyridine and 5g of bromoethane into a beaker, add acetonitrile to dissolve, reflux at 80℃, and react for 24h. After the reaction is complete and a pale yellow solid precipitates, filter and dry to obtain a pale yellow solid 1,1'-diethyl-3,3'-dichloro-[4,4'-bipyridine]-1,1'-diimine;

[0061] ②Then, the obtained pale yellow solid was purified by recrystallization with ethanol;

[0062] ③ Finally, the purified product was dissolved in deionized water and heated to 60°C. After the ammonium hexafluorophosphate was fully dissolved in water, it was slowly added dropwise to the reaction. The addition was stopped when the system no longer became turbid. After stirring for 1 hour, the mixture was filtered and dried to obtain the hexafluorophosphate of the compound: hexafluorophosphate-1,1'-diethyl-3,3'-dichloro-[4,4'-bipyridine]-1,1'-diimide.

[0063] Example 3

[0064] Preparation of compound 3,3'-dibromo-1,1'-diethyl-[4,4'-bipyridine]-1,1'-diimide

[0065] The basic reaction is:

[0066]

[0067] The preparation method includes the following steps:

[0068] ① First, weigh 1g of 3,3'-dibromo-4,4'-bipyridine and 5g of bromoethane into a beaker, add acetonitrile to dissolve, reflux at 80℃, and react for 24h. After the reaction is complete and a pale yellow solid precipitates, filter and dry to obtain a pale yellow solid 1,1'-diethyl-3,3'-dibromo-[4,4'-bipyridine]-1,1'-diimine;

[0069] ②Then, the obtained pale yellow solid was purified by recrystallization with ethanol;

[0070] ③ Finally, the purified product was dissolved in deionized water and heated to 60°C. After the ammonium hexafluorophosphate was fully dissolved in water, it was slowly added dropwise to the reaction. The addition was stopped when the system no longer became turbid. After stirring for 1 hour, the mixture was filtered and dried to obtain the hexafluorophosphate of the compound: hexafluorophosphate-1,1'-diethyl-3,3'-dibromo-[4,4'-bipyridine]-1,1'-diimine.

[0071] Example 4

[0072] Preparation of compound 3,3'-difluoro-1,1'-dihexyl-[4,4'-bipyridine]-1,1'-diimide

[0073] The basic reaction is:

[0074]

[0075] The preparation method includes the following steps:

[0076] ① First, weigh 1g of 3,3'-difluoro-4,4'-bipyridine and 5g of bromohexane into a beaker, add acetonitrile to dissolve, reflux at 80℃, and react for 24h. After the reaction is complete and a pale yellow solid precipitates, filter and dry to obtain a pale yellow solid 1,1'-dihexyl-3,3'-difluoro-[4,4'-bipyridine]-1,1'-diimine;

[0077] ②Then, the obtained pale yellow solid was purified by recrystallization with ethanol;

[0078] ③ Finally, the purified product was dissolved in deionized water and heated to 60°C. After the ammonium hexafluorophosphate was fully dissolved in water, it was slowly added dropwise to the reaction. The addition was stopped when the system no longer became turbid. After stirring for 1 hour, the mixture was filtered and dried to obtain the hexafluorophosphate of the compound: hexafluorophosphate-1,1'-dihexyl-3,3'-difluoro-[4,4'-bipyridine]-1,1'-diimine.

[0079] Example 5

[0080] Preparation of compound 3,3'-dichloro-1,1'-dihexyl-[4,4'-bipyridine]-1,1'-diimide

[0081] The basic reaction is:

[0082]

[0083] The preparation method includes the following steps:

[0084] ① First, weigh 1g of 3,3'-dichloro-4,4'-bipyridine and 5g of bromohexane into a beaker, add acetonitrile to dissolve, reflux at 80℃, and react for 24h. After the reaction is complete and a pale yellow solid precipitates, filter and dry to obtain a pale yellow solid 1,1'-dihexyl-3,3'-dichloro-[4,4'-bipyridine]-1,1'-diimine;

[0085] ②Then, the obtained pale yellow solid was purified by recrystallization with ethanol;

[0086] ③ Finally, the purified product was dissolved in deionized water and heated to 60°C. After the ammonium hexafluorophosphate was fully dissolved in water, it was slowly added dropwise to the reaction. The addition was stopped when the system no longer became turbid. After stirring for 1 hour, the mixture was filtered and dried to obtain the hexafluorophosphate of the compound: hexafluorophosphate-1,1'-dihexyl-3,3'-dichloro-[4,4'-bipyridine]-1,1'-diimine.

[0087] Example 6

[0088] Preparation of compound 3,3'-dibromo-1,1'-dihexyl-[4,4'-bipyridine]-1,1'-diimide

[0089] The basic reaction is:

[0090]

[0091] The preparation method includes the following steps:

[0092] ① First, weigh 1g of 3,3'-dibromo-4,4'-bipyridine and 5g of bromohexane into a beaker, add acetonitrile to dissolve, reflux at 80℃, and react for 24h. After the reaction is complete and a pale yellow solid precipitates, filter and dry to obtain a pale yellow solid 1,1'-dihexyl-3,3'-dibromo-[4,4'-bipyridine]-1,1'-diimine;

[0093] ②Then, the obtained pale yellow solid was purified by recrystallization with ethanol;

[0094] ③ Finally, the purified product was dissolved in deionized water and heated to 60°C. After the ammonium hexafluorophosphate was fully dissolved in water, it was slowly added dropwise to the reaction. The addition was stopped when the system no longer became turbid. After stirring for 1 hour, the mixture was filtered and dried to obtain the hexafluorophosphate of the compound: hexafluorophosphate-1,1'-dihexyl-3,3'-dibromo-[4,4'-bipyridine]-1,1'-diimine.

[0095] Example 7

[0096] Preparation of solid-state electrochromic devices

[0097] At a molar ratio of 4:1:15:60, the six EC materials of Examples 1 to 6 were completely dissolved in acetone with ferrocene, poly(vinylidene fluoride-hexafluoropropylene), and the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide at 50°C.

[0098] The obtained solution was cast onto a glass slide to obtain a uniform freestanding EC gel with a thickness of approximately 60 μm.

[0099] Cut the EC gel into the desired shape using a razor blade and transfer it to the target location on the ITO-coated substrate;

[0100] The gel is sandwiched in another ITO-coated substrate and firmly fixed with double-sided tape to obtain a solid-state electrochromic device.

[0101] The color rendering effect and operational stability were analyzed by applying different DC voltages.

[0102] In Examples 1 to 6, the molecular structures and properties of the parent nuclei 3,3'-difluoro-4,4'-bipyridine, 3,3'-dichloro-4,4'-bipyridine, and 3,3'-dibromo-4,4'-bipyridine in their optimal conformations are shown in Table 1.

[0103] In Examples 1 to 6, the electrochromic EC molecules included tetraphenylpyridine derivatives such as 1,1'-diethyl-3,3'-difluoro-[4,4'-bipyridine]-1,1'-diimine, 3,3'-dichloro-1,1'-diethyl-[4,4'-bipyridine]-1,1'-diimine, 3,3'-dibromo-1,1'-diethyl-[4,4'-bipyridine]-1,1'-diimine, and 3,3'- The molecular structures and properties of difluoro-1,1'-dihexyl-[4,4'-bipyridine]-1,1'-diimine, 3,3'-dichloro-1,1'-dihexyl-[4,4'-bipyridine]-1,1'-diimine, and 3,3'-dibromo-1,1'-dihexyl-[4,4'-bipyridine]-1,1'-diimine are shown in Table 2. In Example 7, the performance values ​​of the six compounds under different direct currents are shown in Table 3.

[0104] Table 1. List of molecular structures and properties under the optimal conformation of the parent nucleus molecule.

[0105]

[0106] Table 2. List of molecular structures and properties of tetraphenylpyridine derivatives

[0107]

[0108]

[0109] Table 3. Performance values ​​of tetraphenylpyridine derivatives

[0110]

[0111] As shown in Tables 1 and 2, the MM2 energy of the EC molecular structure is significantly higher than that of the parent nucleus molecular structure after the introduction of heavy atoms F, Cl, or Br. The energy of the parent nucleus molecular structure gradually increases with the introduction of heavy atoms from F to Br, from 14.3775 Kcal / mol to 26.6357 Kcal / mol. Correspondingly, the energy change of the EC molecular structure is more significant, increasing from 53.2137 Kcal / mol to 70.4172 Kcal / mol. This indicates that the introduction of heavy atoms reduces the stability of the parent nucleus molecular structure, requiring more energy to maintain its conformation, and also suggests that the structure has relatively high scalability.

[0112] As shown in Tables 1 and 2, in the parent nucleus molecular structure, the distance between the heavy atom and the adjacent hydrogen atom increases with the increase of the heavy atom volume, from H(3)-F(14) Added to H(3)-Br(14) Similar distance changes can also be observed in the EC molecular structure, for example, from H(20) to F(18). Increased to H(24)-Br(17) This increase in distance is due to the larger volume of heavy atoms, which causes changes in the spatial arrangement within the molecule.

[0113] As shown in Tables 1 and 2, the dihedral angle of the parent nucleus molecule structure increases significantly with the increase of the volume of heavy atoms, from 29.855° in C(4)-C(3)-C(7)-C(8) to 57.833°. In the EC molecule structure, the dihedral angle also increases with the increase of the volume of heavy atoms, from 20.301° in C(2)-C(3)-C(7)-C(8) to 43.629°. This change indicates that the degree of distortion of the molecular plane increases after the introduction of heavy atoms, making the three-dimensional structure of the molecule more complex.

[0114] As shown in Table 3, the molar absorptivity of the molecules is significantly enhanced after the introduction of heavy atoms. This is because heavy atoms have larger electron clouds, enabling them to interact with photons more effectively and absorb more light. Therefore, the introduction of heavy atoms improves the light absorption capacity of the material, enhancing its electrochromic properties. In practical applications, this means that the material can achieve significant color changes at lower concentrations, improving its performance.

[0115] As shown in Table 3, while the introduction of heavy atoms increases the light absorption capacity of the molecules, it may also negatively impact light transmittance. Due to enhanced light absorption, the material may become opaque, resulting in reduced light transmittance. However, by rationally designing the molecular structure and controlling the amount of heavy atoms introduced, it is possible to maintain relatively high light transmittance while enhancing the molar absorptivity. This is crucial for applications such as electrochromic windows, as light transmittance directly affects the transparency and practicality of the window glass.

[0116] In this invention, under different DC voltages, the long-chain EC material exhibits a higher molar absorptivity and higher transmittance than the short-chain EC material. This is primarily because the longer chain increases the conjugation effect of intramolecular electrons, enhancing light absorption. Simultaneously, the long-chain structure contributes to a more ordered molecular arrangement, reducing light scattering and absorption, thereby improving transmittance. Therefore, the long-chain EC material demonstrates superior electrochromic and optical properties.

[0117] This invention discloses a method for preparing a tetraphenylpyridine derivative for electrochromic materials. The method introduces heavy atoms F, Cl, and Br into the tetraphenylpyridine structure, effectively increasing light absorption. During electrochromic processes, it absorbs more light, enhancing the significance of color changes. The thin-layer structure of this tetraphenylpyridine derivative exhibits excellent light transmittance, while also providing structural stability and durability of the electrochromic material during the electrochromic process. The tetraphenylpyridine derivative displays significant color changes under different DC voltages, and these color changes can be identified and distinguished using the RGB color model, enabling rapid and accurate adjustment of light transmittance in practical applications. The electrochromic response is fast, with the material completing color conversion in a short time, resulting in high color contrast and ensuring significant visual differences under different conditions. The long cycle life improves the practicality and reliability of the electrochromic material, reduces the frequency of replacement and maintenance, and decreases resource consumption and waste generation, meeting environmental protection and sustainable development requirements. It shows promising application prospects in fields such as smart dimming windows, rearview mirrors, displays, and goggles.

[0118] The technical solutions and technical details disclosed in the embodiments of this invention are merely illustrative of the inventive concept of this invention and do not constitute a limitation on the technical solutions of the embodiments of this invention. Any conventional changes, substitutions, or combinations made to the technical details disclosed in the embodiments of this invention have the same inventive concept as this invention and are within the protection scope of the claims of this invention.

Claims

1. A tetraphenylpyridine derivative for use in electrochromic materials, characterized in that, Including compounds represented by any of the following structural formulas: 。 2. The method for preparing the tetraphenylpyridine derivative for electrochromic materials according to claim 1, characterized in that, Methods for preparing compounds containing bromide ions include: using the general formula ( The compound shown in the formula () reacts with bromoalkane to give a compound containing bromide ions; the general formula () )for: （ ); wherein X is any one of F, Cl, and Br, and the bromoalkane is bromoethane or 1-bromohexane; the preparation method of the compound containing hexafluorophosphate ions further includes: recrystallizing the compound containing bromide ions; dissolving the recrystallized product in deionized water and reacting it with ammonium hexafluorophosphate to obtain the compound containing hexafluorophosphate ions.

3. The application of the tetraphenylpyridine derivative for electrochromic materials according to claim 1, characterized in that, Electrochromic materials are prepared using any of the compounds shown in claim 1.

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