A class of quinoxaline-bridged terpyridine iron coordination polymer electrochromic materials

Abstract

The application discloses a quinoxaline-bridged terpyridine iron coordination polymer electrochromic material, and belongs to the electrochromic field. The novel terpyridine iron coordination polymer is related to the application, and the electrochromic performance of the material is regulated by introducing a substituted quinoxaline structural unit into the structure. The quinoxaline-bridged terpyridine iron coordination polymer electrochromic material has the advantages of simple synthesis, high yield, film formation by adopting a solution spin coating process, excellent electrochromic performance, high optical contrast, fast response rate, high coloration efficiency, good cycle stability and potential application value.

Description

Technical Field

[0001] This invention belongs to the field of electrochromism and relates to a class of quinoxaline-bridged terpyridine iron coordination polymer electrochromic materials and their preparation methods. Background Technology

[0002] Electrochromic materials are smart materials whose color can change reversibly under the influence of an external voltage, and they have wide applications in smart windows, displays, security, wearable fabrics, and other fields. To date, electrochromic materials used in this field mainly include transition metal oxides, transition metal coordination polymers, violetin, and organic conjugated polymers. Among them, transition metal coordination polymers combine the advantages of both inorganic and organic materials, and have broad application prospects.

[0003] Ferrous ion Fe 2+ Ferrous ions are widely available and possess excellent redox properties. Furthermore, they readily form stable coordination polymers with pyridine-based polydentate ligands. For example, terpyridine-iron coordination polymers exhibit good electrochromic properties. In molecular design, introducing a conjugated group between two terpyridine structural units is one effective way to regulate their electrochromic properties. The introduced conjugated group plays a crucial role in optimizing electronic structure, improving film-forming properties, regulating spectral absorption properties, enhancing electrochromic optical contrast, accelerating response rate, and improving coloring efficiency and cycling stability. Summary of the Invention

[0004] This invention utilizes molecular design to introduce quinoxaline-based conjugated groups between two terpyridine structural units, constructing a novel class of iron-coordinated polymer electrochromic materials. The quinoxaline-bridged terpyridine iron-coordinated polymer electrochromic materials designed in this invention exhibit excellent electrochromic properties, including high optical contrast, short response time, good cycle stability, and high coloring efficiency. The highest optical contrast ratio reaches 81%, the highest reported for iron-coordinated polymer electrochromic materials to date, demonstrating potential application value.

[0005] This invention provides a class of quinoxaline-bridged terpyridine iron coordination polymer electrochromic materials, with chemical structural formula (I), wherein the R group in the structural formula is methyl, phenyl, or 4-methoxyphenyl:

[0006]

[0007] The method for synthesizing the quinoxaline-bridged terpyridine iron coordination polymer electrochromic material is as follows: 4-formylphenylboronic acid, 2-acetylpyridine, and concentrated ammonia undergo a condensation cyclization reaction to obtain the key intermediate boric acid 1; 3,6-dibromo-o-phenylenediamine is dissolved and condensed with an o-dione to obtain dibromoquinoxaline intermediate 2; intermediate 1 and intermediate 2 undergo a coupling reaction to generate a quinoxaline-bridged terpyridine ligand, which is finally coordinated with ferrous tetrafluoroborate to prepare the target coordination polymer electrochromic material.

[0008] (1) Dissolve 4-formylphenylboronic acid and 2-acetylpyridine in ethanol, add sodium hydroxide powder, and stir at room temperature for 24 hours. Then add concentrated ammonia solution, slowly heat to 80°C, and react overnight. After the reaction is complete, cool to room temperature, filter, wash the filter cake with chloroform, and dry under vacuum to obtain intermediate 1; Dissolve 3,6-dibromo-o-phenylenediamine and o-dione in acetic acid, heat to 100°C under nitrogen protection, and react overnight. After the reaction is complete, cool to room temperature, filter, wash the filter cake with ethanol, and dry under vacuum to obtain intermediate 2;

[0009] (2) Dissolve intermediate 1 and intermediate 2 in a mixed solvent of toluene / water / tert-butanol, add sodium carbonate and bis(triphenylphosphine)palladium dichloride in sequence, then heat to 110°C under nitrogen protection and react overnight. After the reaction is completed, cool to room temperature, wash the filter cake with water and ethanol in sequence, and dry under vacuum to obtain quinoxaline-bridged terpyridine ligand.

[0010] (3) The quinoxaline-bridged terpyridine ligand ligand, iron tetrafluoroborate hexahydrate, was dissolved in a mixed solvent of dichloromethane / methanol. Under nitrogen protection, the temperature was slowly raised to 50°C and the reaction was carried out overnight. After the reaction was completed, the mixture was filtered while hot. The filter cake was washed with water, ethanol, and dichloromethane in sequence and dried under vacuum to obtain the quinoxaline-bridged terpyridine iron coordination polymer electrochromic material.

[0011] The synthesis process is as follows:

[0012]

[0013] In step (1), the molar ratio of 4-formylphenylboronic acid, 2-acetylpyridine, and sodium hydroxide is 1:2.2:6, the reaction temperature is 80℃, and the reaction time is 12-24h; the molar ratio of 3,6-dibromo-o-phenylenediamine to o-dione is 1:1, the reaction temperature is 100℃, and the reaction time is 12-24h.

[0014] In step (2), the molar ratio of intermediate 1, intermediate 2, sodium carbonate and bis(triphenylphosphine)palladium dichloride is 4:1:10:0.1, the volume ratio of solvent toluene, water and tert-butanol is 3:3:1, the reaction temperature is 110℃, and the reaction time is 24-36h.

[0015] In step (3), the molar ratio of quinoxaline-bridged terpyridine ligand to ferric tetrafluoroborate hexahydrate is 1:1, the volume ratio of dichloromethane to methanol is 1:1, and the reaction time is 12-24 h.

[0016] The electrochromic material prepared by this invention is a type of quinoxaline-bridged terpyridine iron coordination polymer. Its electrochromic performance was tested using a three-electrode system, with the electrochromic layer as the working electrode, a platinum wire as the counter electrode, an Ag / AgCl electrode as the reference electrode, and a 0.1 mol / L tetrabutylammonium tetrafluoroborate dichloromethane solution as the electrolyte.

[0017] The electrochromic layer is prepared by dissolving the iron-coated polymer in N,N-dimethylformamide. The concentration of the N,N-dimethylformamide solution of the iron-coated polymer is 60-100 mg / mL. The solution is then coated onto a cleaned indium tin oxide conductive glass. The rotation speed is 1000-3000 r / min and the rotation time is 60 s. After spin coating, the resulting film is sintered at 60 °C for 30 min.

[0018] This invention has the following advantages:

[0019] The quinoxaline-bridged terpyridine iron coordination polymer electrochromic material designed in this invention has a simple synthesis route, is easy to purify, and has a high yield. This quinoxaline-bridged terpyridine iron coordination polymer electrochromic material exhibits excellent electrochromic properties, with a fast response rate, good cycling stability, high coloring efficiency, and a maximum optical contrast ratio of up to 81%. Attached Figure Description

[0020] Figure 1 The infrared spectrum of the quinoxaline-bridged tripyridine iron coordination polymer with R being methyl prepared in Example 1 of this invention.

[0021] Figure 2 The infrared spectrum of the quinoxaline-bridged tripyridine iron coordination polymer with R being phenyl prepared in Example 2 of this invention.

[0022] Figure 3 The infrared spectrum of the quinoxaline-bridged tripyridine iron coordination polymer with R being 4-methoxyphenyl prepared in Example 3 of this invention.

[0023] Figure 4 Absorption spectra of the electrochromic thin film of quinoxaline-bridged terpyridine iron coordination polymer with R being methyl, prepared according to the present invention, at different voltages.

[0024] Figure 5 The transmittance versus time curve and response time curve of the quinoxaline-bridged terpyridine iron coordination polymer electrochromic film with R being methyl prepared according to the present invention.

[0025] Figure 6 Cyclic stability test results of the quinoxaline-bridged terpyridine iron coordination polymer electrochromic film with R being methyl prepared according to the present invention.

[0026] Figure 7 The molecular structure diagram shows the electrochromic material of the quinoxaline-bridged terpyridine iron coordination polymer with R being methyl, prepared according to the present invention. Detailed Implementation

[0027] Example 1: Synthesis of a quinoxaline-bridged terpyridine iron coordination polymer with R being methyl

[0028] (1) Preparation of intermediate (4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)boronic acid

[0029] 4-Formylphenylboronic acid (3.0 g, 20 mmol) and 2-acetylpyridine (5.3 g, 44 mmol) were dissolved in 100 mL of ethanol solution, and sodium hydroxide powder (4.8 g, 120 mmol) was added. The mixture was stirred at room temperature for 24 hours under nitrogen protection. Then, 75 mL of 25% ammonia solution was added, and the temperature was slowly raised to 80 °C and maintained for 20 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, and the filter cake was washed with chloroform and dried under vacuum to give the intermediate (4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)boronic acid (5.65 g, yield 80%). 1 H NMR (600MHz, MeOD) δ8.70 (d, J=4.8Hz, 2H), 8.67 (s, 2H), 8.65 (d, J=8.4Hz, 2H), 8.00 ( t, J=7.8Hz, 2H), 7.77 (d, J=7.2Hz, 2H), 7.73 (d, J=7.2Hz, 2H), 7.50 (t, J=6.0Hz, 2H).

[0030] (2) Preparation of intermediate 5,8-dibromo-2,3-dimethylquinoxaline

[0031] 3,6-Dibromophenyl-1,2-diamine (600 mg, 2.25 mmol) and 2,3-butanedione (149 mg, 1.73 mmol) were dissolved in acetic acid (30 mL). The mixture was heated to 100 °C under nitrogen protection and stirred for 12 h. After the reaction was complete, the mixture was cooled to room temperature, filtered, and the filter cake was washed with anhydrous ethanol and dried under vacuum to give the intermediate 5,8-dibromo-2,3-dimethylquinoxaline (462 mg, yield 85%). 1 H NMR (600MHz, CDCl3) δ7.84 (s, 2H), 2.83 (s, 6H).

[0032] (3) Preparation of ligand 5,8-bis(4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)-2,3-dimethylquinoxaline

[0033] Intermediate (4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)boronic acid (1793 mg, 5.08 mmol) and intermediate 5,8-dibromo-2,3-dimethylquinoxaline (400 mg, 1.27 mmol) were dissolved in a mixed solvent (50 mL) of toluene / water / tert-butanol (3 / 3 / 1, v / v / v). Sodium carbonate (1346 mg, 12.7 mmol) and bis(triphenylphosphine)palladium(II) chloride (91 mg, 0.13 mmol) were added sequentially. The mixture was slowly heated to 110 °C under nitrogen protection and stirred for 24 h. After the reaction was completed, the mixture was cooled to room temperature, and the filter cake was washed sequentially with water and ethanol and dried under vacuum to obtain ligand 5,8-bis(4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)-2,3-dimethylquinoxaline (666 mg, yield 68%). 1 H NMR (600MHz, CDCl3) δ8.88 (s, 4H), 8.77 (d, J = 4.2Hz, 4H), 8.71 (d, J = 8.4Hz, 4H), 8.10 (d, J = 7.8Hz , 4H), 7.97 (d, J=8.4Hz, 4H), 7.92-7.88 (m, 6H), 7.38 (dd, J1=7.2Hz, J2=4.8Hz, 4H), 2.74 (s, 6H).

[0034] (4) Synthesis of quinoxaline-bridged terpyridine iron coordination polymers with R being methyl

[0035] The ligands 5,8-bis(4-([2,2′:6′,2″-terpyridinyl]-4′-yl)phenyl)-2,3-dimethylquinoxaline (500 mg, 0.67 mmol) and ferric tetrafluoroborate hexahydrate (107 mg, 0.67 mmol) were dissolved in a 30 mL mixture of dichloromethane / methanol (1:1, v / v). The mixture was heated to 50 °C under nitrogen protection and stirred for 12 h. After the reaction was completed, the mixture was cooled to room temperature, and the filter cake was washed successively with water, ethanol, and dichloromethane to obtain a purple solid. The solid was then dried in a vacuum drying oven to obtain the target iron coordination polymer.

[0036] Example 2: Synthesis of a quinoxaline-bridged terpyridine iron coordination polymer with R being phenyl

[0037] (1) Preparation of intermediate 5,8-dibromo-2,3-diphenylquinoxaline

[0038] Intermediate 3,6-dibromophenyl-1,2-diamine (600 mg, 2.25 mmol) and 1,2-diphenylethylenedione (363 mg, 1.73 mmol) were dissolved in acetic acid (30 mL). The mixture was heated to 100 °C under nitrogen protection and stirred for 12 h. After the reaction was complete, the mixture was cooled to room temperature, filtered, and the filter cake was washed with anhydrous ethanol and dried under vacuum to give intermediate 5,8-dibromo-2,3-diphenylquinoxaline (682 mg, 90% yield). 1 H NMR (600MHz, CDCl3) δ7.92 (s, 2H), 7.68-7.64 (m, 4H), 7.43-7.39 (m, 2H), 7.38-7.34 (m, 4H).

[0039] (2) Preparation of ligand 5,8-bis(4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)-2,3-diphenylquinoxaline

[0040] (4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)boronic acid (1285 mg, 3.64 mmol) and intermediate 5,8-dibromo-2,3-diphenylquinoxaline (400 mg, 0.91 mmol) were dissolved in a mixed solvent of toluene / water / tert-butanol (3 / 3 / 1, v / v / v) (50 mL). Sodium carbonate (965 mg, 9.1 mmol) and bis(triphenylphosphine)palladium(II) chloride (64 mg, 0.091 mmol) were added sequentially. The mixture was slowly heated to 110 °C under nitrogen protection and stirred for 24 h. After the reaction was completed, the mixture was cooled to room temperature, and the filter cake was washed with water and ethanol sequentially and dried under vacuum to obtain the ligand 5,8-bis(4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)-2,3-diphenylquinoxaline (595 mg, 73%). 1 H NMR (600MHz, CDCl3) δ8.89 (s, 4H), 8.78 (d, J = 4.2Hz, 4H), 8.72 (d, J = 7.8Hz, 4H), 8.15 (d, J = 8.4Hz, 4H), 8.07 (d, J = 8.4Hz, 4H), 8.02 (s , 2H), 7.91 (td, J1=7.8Hz, J2=1.8Hz, 4H), 7.66 (dd, J1=6.0Hz, J2=2.4Hz, 4H), 7.40-7.37 (m, 4H), 7.34 (dd, J1=5.4Hz, J2=1.8Hz, 6H).

[0041] (3) Synthesis of quinoxaline-bridged tripyridine iron coordination polymers with R being phenyl

[0042] The ligands 5,8-bis(4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)-2,3-diphenylquinoxaline (500 mg, 0.56 mmol) and ferric tetrafluoroborate hexahydrate (90 mg, 0.56 mmol) were dissolved in a 30 mL mixture of dichloromethane / methanol (1:1, v / v). The mixture was heated to 50 °C under nitrogen protection and stirred for 12 h. After the reaction was completed, the mixture was cooled to room temperature, and the filter cake was washed successively with water, ethanol, and dichloromethane to obtain a purple solid. The solid was then dried in a vacuum drying oven to obtain the target iron coordination polymer.

[0043] Example 3: Synthesis of a 4-methoxyphenyl quinoxaline-bridged terpyridine iron coordination polymer

[0044] (1) 5,8-Dibromo-2,3-bis(4-methoxyphenyl)quinoxaline

[0045] Intermediate 3,6-dibromophenyl-1,2-diamine (600 mg, 2.25 mmol) and 1,2-bis(4-methoxyphenyl)-1,2-ethylenedione (467 mg, 1.73 mmol) were dissolved in acetic acid (30 mL). The mixture was heated to 100 °C under nitrogen protection and stirred for 12 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, and the filter cake was washed with anhydrous ethanol and dried under vacuum to give intermediate 5,8-dibromo-2,3-bis(4-methoxyphenyl)quinoxaline (758 mg, 88%). 1 H NMR (600MHz, CDCl3) δ7.86 (s, 2H), 7.66 (d, J=9Hz, 4H), 6.90 (d, J=9Hz, 4H), 3.85 (s, 6H).

[0046] (2) Preparation of ligand 5,8-bis(4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)-2,3-bis(4-methoxyphenyl)quinoxaline

[0047] The intermediates (4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)boronic acid (1594 mg, 3.2 mmol) and 5,8-dibromo-2,3-bis(4-methoxyphenyl)quinoxaline (400 mg, 0.80 mmol) were dissolved in a mixed solvent (50 mL) of toluene / water / tert-butanol (3 / 3 / 1, v / v / v), and sodium carbonate (848 mg, 8.0 mmol) was added sequentially. ), bis(triphenylphosphine)palladium(II) chloride (56 mg, 0.08 mmol), were slowly heated to 110 °C under nitrogen protection and stirred for 24 h. After the reaction was completed, the mixture was cooled to room temperature, and the filter cake was washed successively with water and ethanol and dried under vacuum to obtain the ligand 5,8-bis(4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)-2,3-bis(4-methoxyphenyl)quinoxaline (543 mg, 71%). 1 H NMR (600MHz, CDCl3) δ8.90 (s, 4H), 8.78 (d, J = 4.2Hz, 4H), 8.72 (d, J = 7.8Hz, 4H), 8.14 (d, J = 8.4Hz, 4H), 8.06 (d, J = 8.4Hz, 4H), 7.96 (s, 2H), 7.91 (td, J1=7.8Hz, J2=1.8Hz, 4H), 7.64 (d, J=8.4Hz, 4H), 7.40-7.38 (m, 4H), 6.89 (d, J=9.0Hz, 4H), 3.83 (s, 6H).

[0048] (3) Synthesis of 4-methoxyphenyl quinoxaline-bridged terpyridine iron coordination polymer

[0049] The ligands 5,8-bis(4-([2,2′:6′,2″-terpyridine]-4′-yl)phenyl)-2,3-bis(4-methoxyphenyl)quinoxaline (500 mg, 0.52 mmol) and ferric tetrafluoroborate hexahydrate (84 mg, 0.52 mmol) were dissolved in a 30 mL mixture of dichloromethane / methanol (1:1, v / v). The mixture was heated to 50 °C under nitrogen protection and stirred for 12 h. After the reaction was completed, the mixture was cooled to room temperature, and the filter cake was washed successively with water, ethanol, and dichloromethane to obtain a purple solid. The solid was then dried in a vacuum drying oven to obtain the target iron coordination polymer.

[0050] Example 4: Preparation and electrochromic performance testing of quinoxaline-bridged terpyridine iron coordination polymer electrochromic films with R being methyl

[0051] First, the indium tin oxide conductive glass was ultrasonically cleaned in ethanol and acetone solutions for 10 min each, and then placed in a UV ozone cleaner for 20 min. Using a pipette, 20 μL of an 80 mg / mL solution of N,N-dimethylformamide, a quinoxaline-bridged tripyridine iron coordination polymer (R = methyl), was dropped onto a clean indium tin oxide conductive glass plate. Spin coating was then performed at 1000 rpm for 60 s. After spin coating, the resulting film was sintered at 60 °C for 30 min.

[0052] The electrochromic properties of the quinoxaline-bridged terpyridine iron coordination polymer film (R: methyl) were tested in a three-electrode system. The electrochromic layer was used as the working electrode, a platinum wire as the counter electrode, and an Ag / AgCl electrode as the reference electrode. The electrolyte was a 0.1 mol / L tetrabutylammonium tetrafluoroborate solution in dichloromethane. The chronoamperometry was used at the corresponding absorption maximum λ. max The response curves of voltage switching between oxidized and reduced states in a stepwise manner were recorded at a transmittance T over time at 574 nm, with a potential pulse width of 10 s. Figure 4 As shown, during the application of voltage, the absorption peak of the methyl-quinoxaline-bridged terpyridine iron coordination polymer electrochromic film shifted from 574 nm to 412 nm, and the electrochromic film changed from purple to light yellow. Figure 5 As shown, the quinoxaline-bridged terpyridine iron coordination polymer electrochromic film with R representing methyl exhibits high optical contrast, up to 81%, with fading and coloring times of 2.1 s and 0.5 s, respectively. The coloring efficiency of this electrochromic material is 460 cm⁻¹. 2 / C. For example... Figure 6 As shown, the terpyridine iron coordination polymer electrochromic film with R being methyl quinoxaline bridged retains 90% of its initial optical contrast after 150 cycles of repeated testing, demonstrating good stability.

Claims

1. A class of quinoxaline-bridged terpyridine iron coordination polymer electrochromic materials, characterized in that, Chemical structural formula with formula (Ⅰ): ； Formula I In the structural formula, the R group is one of methyl, phenyl, or 4-methoxyphenyl.

2. The quinoxaline-bridged terpyridine iron coordination polymer electrochromic material according to claim 1, characterized in that, Its electrochromic properties were tested using a three-electrode system, with the electrolyte being a 0.1 mol / L tetrabutylammonium tetrafluoroborate solution in dichloromethane. The three-electrode system refers to using the electrochromic layer as the working electrode, a platinum wire as the counter electrode, and an Ag / AgCl electrode as the reference electrode.

3. The quinoxaline-bridged terpyridine iron coordination polymer electrochromic material according to claim 2, characterized in that, The electrochromic layer is prepared by dissolving the prepared iron coordination polymer in N,N-dimethylformamide, coating the solution onto cleaned indium tin oxide conductive glass, and preparing a uniform and smooth electrochromic film with indium tin oxide conductive glass as the substrate by spin coating, and then sintering at 60°C for 30 min.

4. The quinoxaline-bridged terpyridine iron coordination polymer electrochromic material according to claim 3, characterized in that, The concentration of the N,N-dimethylformamide solution of the iron coordination polymer was 60 ~ 100 mg / mL, the rotation speed was 1000 ~ 3000 r / min, and the rotation time was 60 s.

5. The method for preparing a type of quinoxaline-bridged terpyridine iron coordination polymer electrochromic material according to claim 1, characterized in that, The preparation steps include the following: ； Formula II (1) Dissolve 4-formylphenylboronic acid and 2-acetylpyridine in ethanol, add sodium hydroxide powder, stir at room temperature for 24 hours, then add concentrated ammonia solution, slowly heat to 80°C, react overnight, after the reaction is completed, cool to room temperature, filter, wash the filter cake with chloroform, and vacuum dry to obtain intermediate 1; Dissolve 3,6-dibromo-o-phenylenediamine and o-dione in acetic acid, heat to 100°C under nitrogen protection, react overnight, after the reaction is completed, cool to room temperature, filter, wash the filter cake with ethanol, and vacuum dry to obtain intermediate 2; (2) Dissolve intermediate 1 and intermediate 2 in a mixed solvent of toluene / water / tert-butanol, add sodium carbonate and bis(triphenylphosphine)palladium dichloride in sequence, then heat to 110°C under nitrogen protection and react overnight. After the reaction is completed, cool to room temperature, wash the filter cake with water and ethanol in sequence, and dry under vacuum to obtain quinoxaline-bridged terpyridine ligand. (3) The quinoxaline-bridged terpyridine ligand ligand, iron tetrafluoroborate hexahydrate, was dissolved in a mixed solvent of dichloromethane / methanol. Under nitrogen protection, the temperature was slowly raised to 50°C and the reaction was carried out overnight. After the reaction was completed, the mixture was filtered while hot. The filter cake was washed with water, ethanol, and dichloromethane in sequence and dried under vacuum to obtain the quinoxaline-bridged terpyridine iron coordination polymer electrochromic material.

6. The method for preparing a type of quinoxaline-bridged terpyridine iron coordination polymer electrochromic material according to claim 5, characterized in that, In the preparation method described above: in step (1), the molar ratio of 4-formylphenylboronic acid, 2-acetylpyridine, and sodium hydroxide is 1:2.2:6, the reaction temperature is 80℃, and the reaction time is 12~24 h; the molar ratio of 3,6-dibromo-o-phenylenediamine to o-dione is 1:1, the reaction temperature is 100℃, and the reaction time is 12~24 h.

7. The method for preparing a type of quinoxaline-bridged terpyridine iron coordination polymer electrochromic material according to claim 5, characterized in that, In the preparation method described above: in step (2), the molar ratio of intermediate 1, intermediate 2, sodium carbonate and bis(triphenylphosphine)palladium dichloride is 4:1:10:0.1, the volume ratio of solvent toluene, water and tert-butanol is 3:3:1, the reaction temperature is 110℃, and the reaction time is 24~36 h.

8. The method for preparing a type of quinoxaline-bridged terpyridine iron coordination polymer electrochromic material according to claim 5, characterized in that, In the preparation method described above: in step (3), the molar ratio of quinoxaline-bridged terpyridine ligand to ferric tetrafluoroborate hexahydrate is 1:1, the volume ratio of dichloromethane to methanol is 1:1, and the reaction time is 12 to 24 h.

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