Preparation and application of aromatic ester electrochromic materials based on spirobipropyldioxythiophene

Abstract

The present invention discloses two aromatic ester electrochromic materials with helical dipropyldioxythiophene as the core, and applies them to electrochromic devices. Compared with traditional aromatic ester electrochromic materials, the two novel electrochromic materials with dipropyldioxythiophene as the core designed by the present invention have the advantages of simple synthesis route, low cost, simple device preparation, high optical contrast, fast response rate, good cycle stability, etc., and have potential application value.

Description

Technical Field

[0001] The invention relates to the technical field of electrochromic materials, and in particular to two aromatic ester electrochromic materials and preparation methods and applications thereof. Background Art

[0002] With the progress of human society and the development of science and technology, higher requirements are put forward for the research of new materials. As a new type of green, energy-saving and environmentally friendly intelligent material, electrochromic materials have broad application prospects in the fields of smart windows, color-changing mirrors, anti-glare rearview mirrors for cars, electronic displays, and military stealth materials, and have attracted much attention in recent years. Organic small molecule electrochromic materials have rich structures, simple synthesis, adjustable colors, and are suitable for all-in-one electrochromic devices, and have broad application prospects.

[0003] Aromatic ester compounds can undergo reversible redox reactions under voltage drive and show obvious and rich color changes, and can be used to prepare all-in-one electrochromic devices. Introducing conjugated groups to connect two or more ester structural units is a common method to regulate the performance of aromatic ester electrochromic materials. However, the introduction of conjugated groups often leads to molecular aggregation and reduces the cyclic stability of electrochromic materials. Therefore, the molecular structure design of the conjugated connection unit is of great significance to improving the performance of aromatic ester electrochromic materials. Summary of the invention

[0004] The present invention uses molecular design, takes spirobipropyldioxythiophene as the core, introduces methyl benzoate or m-dimethyl benzoate structural units through Suzuki coupling reaction, and constructs two novel aromatic ester electrochromic materials. The spirobipropyl structure in the middle of the material molecule effectively avoids the stacking phenomenon of the molecule during the electrochemical redox process. The electrochromic material with spirobipropyldioxythiophene as the core designed by the present invention has the advantages of simple synthesis route, low cost, simple device preparation, high optical contrast, fast response rate, good cycle stability, etc.

[0005] The novel electrochromic material involved in the present invention has a chemical structural formula (I):

[0006]

[0007] The synthesis method of the aromatic ester electrochromic materials XEDOT-1 and XEDOT-2 with spirobipropyldioxythiophene as the core is as follows: 3,4-dimethoxythiophene and pentaerythritol are subjected to an etherification reaction under the catalysis of p-toluenesulfonic acid to obtain spirobipropyldioxythiophene; then the etherification reaction is carried out with N-bromosuccinimide to obtain tetrabromospirobipropyldioxythiophene; and then the etherification reaction is carried out with aromatic ester boric acid to obtain the target aromatic ester electrochromic materials XEDOT-1 and XEDOT-2.

[0008] (1) 3,4-dimethoxythiophene and pentaerythritol were dissolved in toluene, p-toluenesulfonic acid was added, and the mixture was heated under reflux for 24 h under nitrogen protection. After the reaction was completed, the solvent was dried, water was added to the residue, and the mixture was filtered. The obtained solid was washed with ethanol and dried in vacuo to obtain intermediate 1;

[0009] (2) Dissolve intermediate 1 in N,N-dimethylformamide, add N-bromosuccinimide at room temperature, raise the temperature to 80 degrees, stir and react for 12 hours. After the reaction is completed, pour the reaction solution into water, filter, wash the obtained solid with ethanol, and vacuum dry to obtain intermediate 2;

[0010] (3) The intermediate 2,4-methoxycarbonylphenylboronic acid, potassium carbonate, and tetrakis(triphenylphosphine)palladium are added to the reaction flask in sequence, and then 1,4-dioxane and distilled water are added, the reaction system is evacuated and filled with nitrogen, the temperature is slowly raised to 90° C., and the reaction is refluxed overnight. After the reaction is completed, the reaction is concentrated under reduced pressure, extracted with dichloromethane, and the organic phase is washed with saturated brine, dried over anhydrous sodium sulfate, the solvent is dried, and purified by column chromatography to obtain XEDOT-1;

[0011] (4) The intermediate 2, 3,5-bis(methoxycarbonyl)phenylboronic acid, potassium carbonate, and tetrakis(triphenylphosphine)palladium are added to the reaction flask in sequence, and then 1,4-dioxane and distilled water are added. The reaction system is evacuated and filled with nitrogen. The temperature is slowly raised to 90° C. and refluxed overnight. After the reaction is completed, the reaction is concentrated under reduced pressure and extracted with dichloromethane. The organic phase is washed with saturated brine, dried over anhydrous sodium sulfate, the solvent is spin-dried, and purified by column chromatography to obtain XEDOT-2.

[0012] The synthesis process is:

[0013]

[0014] In step (1), the molar ratio of 3,4-dimethoxythiophene, pentaerythritol and p-toluenesulfonic acid is 1:6:0.1, the reaction temperature is 110° C., and the reaction time is 16 to 28 hours.

[0015] In step (2), the molar ratio of intermediate 1 to N-bromosuccinimide is 1:6.

[0016] In step (3), the molar ratio of the intermediate 2,4-methoxycarbonylphenylboronic acid, potassium carbonate and tetrakis(triphenylphosphine)palladium is 1:6:18:0.1, and the reaction time is 16 to 28 hours.

[0017] In step (4), the molar ratio of the intermediate 2, 3,5-bis(methoxycarbonyl)phenylboronic acid, potassium carbonate and tetrakis(triphenylphosphine)palladium is 1:6:18:0.1, and the reaction time is 16 to 28 hours.

[0018] The aromatic ester electrochromic materials XEDOT-1 and XEDOT-2 with the spiral dipropyldioxythiophene as the core prepared in the present invention are made into an all-in-one liquid electrochromic device, wherein the all-in-one liquid electrochromic device is composed of two ITO glasses and a liquid electrolyte, and the specific steps are as follows:

[0019] (1) Cut the ITO glass into 1.5×2.5cm 2 , then ultrasonically cleaned with deionized water, acetone and isopropanol for 15 min respectively, and then dried with nitrogen;

[0020] (2) Use a sarling film to bond two pieces of ITO glass of the same size together through a press machine. There should be a certain distance between the two pieces of ITO glass. When the sarling film is bonded, a small hole should be left to facilitate the infusion of liquid electrolyte.

[0021] (3) Weigh 0.05 M of aromatic ester electrochromic material, 0.05 M of ferrocene and 0.5 M of tetrabutylammonium tetrafluoroborate and dissolve them in 0.1 mL of N-methylpyrrolidone to prepare the all-in-one liquid electrochromic device electrolyte;

[0022] (4) replacing the air in the cavity of the all-in-one liquid electrochromic device with nitrogen;

[0023] (5) injecting the prepared all-in-one liquid electrochromic electrolyte into the cavity of the all-in-one liquid electrochromic device through a pressure difference;

[0024] (6) Use UV curing glue to seal the device.

[0025] The present invention has the following advantages:

[0026] The electrochromic devices prepared from two electrochromic materials with dipropyldioxythiophene as the core designed in the present invention have the advantages of simple synthesis route, low cost, simple device preparation, fast response speed, good cycle stability, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the molecular structure of the electrochromic material XEDOT-1 synthesized in Example 1 of the present invention.

[0028] Figure 2 This is the molecular structure of the electrochromic material XEDOT-2 synthesized in Example 2 of the present invention.

[0029] Figure 3 The graphs are absorption spectra of the electrochromic device based on the electrochromic material XEDOT-1 synthesized in Example 1 of the present invention at different voltages.

[0030] Figure 4The graphs are absorption spectra of the electrochromic device based on the electrochromic material XEDOT-2 synthesized in Example 2 of the present invention at different voltages. DETAILED DESCRIPTION

[0031] Embodiment 1:

[0032] Synthesis of electrochromic material XEDOT-1 and its application in electrochromic devices:

[0033]

[0034] (1) 3,4-dimethoxythiophene (6 g, 41.8 mmol), pentaerythritol (34.2 g, 250.1 mmol), p-toluenesulfonic acid (798 mg, 4.18 mmol) were added to 500 mL of toluene solution and stirred continuously. Under nitrogen protection, the temperature was set to 110° C. and the reaction was heated to reflux for 24 h. After the reaction was completed, the mixed solvent was dried, water was added to the residue, filtered, and the obtained solid was washed with ethanol to obtain intermediate 1 (2 g), with a yield of 62%.

[0035] (2) Intermediate 1 (1 g, 2.38 mmol) was dissolved in 50 mL of N,N-dimethylformamide solution, N-bromosuccinimide (3.6 g, 20.5 mmol) was added at room temperature, and then the reaction temperature was raised to 80°C and stirred for 12 h. After the reaction was completed, the reaction solution was poured into water and filtered. The obtained solid was washed with ethanol and vacuum dried to obtain Intermediate 2 (1.58 g) with a yield of 78%.

[0036] (3) The intermediate 2 (100 mg, 163.4 mmol), 4-methoxycarbonylphenylboronic acid (0.18 g, 9.8 mmol), potassium carbonate (405.9 mg, 2.94 mmol), and tetrakis(triphenylphosphine)palladium (18.9 mg, 16.4 mmol) were added to a 100 mL reaction bottle in sequence, and then 20 mL of 1,4-dioxane and 4 mL of distilled water were added. The reaction was evacuated and filled with nitrogen. The reaction temperature was 90° C. and refluxed for 24 h. After the reaction was completed by spot plate monitoring, extraction was performed, and finally XEDOT-1 was purified by column chromatography with a yield of 75%. 1 H NMR (600MHz, CDCl3) δ 8.08 (d, J=8.5Hz, 8H), 7.84 (d, J=8.5Hz, 8H), 4.36 (s, 8H), 3.95 (s, 12H).

[0037] The electrochromic device prepared above was tested. The XEDOT-1-based electrochromic device changed from colorless to blue-green under applied voltage, with an optical contrast of 65% at 610 nm, a coloring time of 1.3 s, a fading time of 1.7 s, and a coloring efficiency of 358.6 cm 2 / C, the optical contrast retained 85% of the initial value after cycling for 500 s.

[0038] Embodiment 2:

[0039] Synthesis of electrochromic material XEDOT-2 and its application in electrochromic devices:

[0040]

[0041] (1) 3,4-dimethoxythiophene (6 g, 41.8 mmol), pentaerythritol (34.2 g, 250.1 mmol), p-toluenesulfonic acid (798 mg, 4.18 mmol) were added to 500 mL of toluene solution and stirred continuously. Under nitrogen protection, the temperature was set to 110° C. and the reaction was heated to reflux for 24 h. After the reaction was completed, the mixed solvent was dried, water was added to the residue, filtered, and the obtained solid was washed with ethanol to obtain intermediate 1 (2 g), with a yield of 62%.

[0042] (2) Intermediate 1 (1 g, 2.38 mmol) was dissolved in 50 mL of N,N-dimethylformamide solution, N-bromosuccinimide (3.6 g, 20.5 mmol) was added at room temperature, and then the reaction temperature was raised to 80°C and stirred for 12 h. After the reaction was completed, the reaction solution was poured into water and filtered. The obtained solid was washed with ethanol and vacuum dried to obtain Intermediate 2 (1.58 g) with a yield of 78%.

[0043] (3) Preparation of XEDOT-2: Intermediate 2 (100 mg, 0.16 mmol), 3,5-bis(methoxycarbonyl)phenylboronic acid (0.12 g, 0.51 mmol), potassium carbonate (203 mg, 1.47 mmol), and tetrakis(triphenylphosphine)palladium (10 mg, 0.0087 mmol) were added to a 50 mL reaction bottle in sequence, and then 10 mL of ethylene glycol dimethyl ether was added. The reaction was evacuated and filled with nitrogen. The reaction temperature was 95° C. and refluxed for 24 h. After the reaction was completed by spot plate monitoring, extraction was performed, and finally XEDOT-2 was purified by column chromatography, with a final yield of 70%. 1 H NMR (600MHz, CDCl3) δ8.21 (s, 4H), 7.88 (s, 8H), 4.37 (s, 8H), 3.98 (s, 24H).

[0044] The above-synthesized new materials XEDOT-1 and XEDOT-2 are applied to electrochromic devices, and the preparation process is as follows:

[0045] Cut the 1.5×2.5cm 2 The indium tin oxide conductive glass was ultrasonically cleaned with deionized water, acetone and isopropanol for 15 minutes respectively, and then dried with nitrogen. Then two pieces of indium tin oxide conductive glass were staggered at a certain distance, and three sides of them were bonded together using a sarin film, leaving a small hole on the remaining side. The size of the sarin film cavity was 1.4×1.7cm 2 , and finally the device was packaged with a press (pressed at 0.1MPa, 130℃ for 50s), and finally an all-in-one liquid electrochromic device was formed. Weigh 0.05M electrochromic material, 0.05M ferrocene and 0.5M tetrabutylammonium tetrafluoroborate and dissolve them in 0.1mL of N-methylpyrrolidone, and the electrolyte of the all-in-one liquid electrochromic device is prepared. The cavity of the all-in-one liquid electrochromic device is replaced with nitrogen, and then the all-in-one liquid electrochromic device electrolyte is injected into the device using a pressure difference, and finally the reserved small holes are sealed using ultraviolet light curing glue.

[0046] The electrochromic device prepared above was tested. The XEDOT-2-based electrochromic device changed from colorless to green under applied voltage, with an optical contrast of 72% at 595 nm, a coloring time of 1.5 s, a fading time of 1.9 s, and a coloring efficiency of 315.3 cm 2 / C, the optical contrast retained 80% of the initial value after cycling for 500 s.

Claims

1. Two kinds of aromatic ester electrochromic materials with helical bispropyldioxythiophene as core, characterized in that: Having the chemical structural formula of formula (I) and formula (II):

2. The method for preparing two aromatic ester electrochromic materials XEDOT-1 and XEDOT-2 with spirodipropyldioxythiophene as the core according to claim 1, characterized in that: The steps include: (1) Preparation of Intermediate 1: 3,4-dimethoxythiophene and pentaerythritol were dissolved in toluene, p-toluenesulfonic acid was added, and the mixture was heated under reflux for 24 h under nitrogen protection. After the reaction was completed, the solvent was dried by spin drying, water was added to the residue, and the residue was filtered. The obtained solid was washed with ethanol and dried in vacuo to obtain Intermediate 1; (2) Preparation of intermediate 2: Intermediate 1 was dissolved in N,N-dimethylformamide, N-bromosuccinimide was added at room temperature, the temperature was raised to 80°C, and the reaction was stirred overnight. After the reaction was completed, the reaction solution was poured into water and filtered. The obtained solid was washed with ethanol and dried in vacuo to obtain intermediate 2; (3) Preparation of XEDOT-1: The intermediate 2,4-methoxycarbonylphenylboronic acid, potassium carbonate, and tetrakis(triphenylphosphine)palladium were added to a reaction flask in sequence, and then 1,4-dioxane and distilled water were added. The reaction system was evacuated and filled with nitrogen. The temperature was slowly raised to 90° C. and the reaction was carried out for 24 hours. After the reaction was completed, the reaction was concentrated under reduced pressure and extracted with dichloromethane. The organic phase was washed with saturated brine, dried over anhydrous sodium sulfate, the solvent was dried, and purified by column chromatography to obtain XEDOT-1; (4) Preparation of XEDOT-2: The intermediate 2, 3,5-bis(methoxycarbonyl)phenylboronic acid, potassium carbonate, and tetrakis(triphenylphosphine)palladium were added to a reaction flask in sequence, and then 1,4-dioxane and distilled water were added. The reaction system was evacuated and filled with nitrogen. The temperature was slowly raised to 90° C. and refluxed overnight. After the reaction was completed, the reaction was concentrated under reduced pressure and extracted with dichloromethane. The organic phase was washed with saturated brine, dried over anhydrous sodium sulfate, the solvent was dried, and purified by column chromatography to obtain XEDOT-2.

3. The method for preparing two aromatic ester electrochromic materials XEDOT-1 and XEDOT-2 with spirodipropyldioxythiophene as the core according to claim 2, characterized in that: In the synthesis method: in step (1), the molar ratio of 3,4-dimethoxythiophene, pentaerythritol and p-toluenesulfonic acid is 1:6:0.1, and the reaction temperature is 110°C.

4. The method for preparing two aromatic ester electrochromic materials XEDOT-1 and XEDOT-2 with spirodipropyldioxythiophene as the core according to claim 2, characterized in that: In the synthesis method, the molar ratio of intermediate 1 to N-bromosuccinimide in step (2) is 1:

6.

5. The method for preparing the aromatic ester electrochromic material XEDOT-1 with helical bispropyldioxythiophene as the core according to claim 2, characterized in that: In the synthesis method, the molar ratio of the intermediate 2, 4-methoxycarbonylphenylboronic acid, potassium carbonate and tetrakis(triphenylphosphine)palladium in step (3) is 1:6:18:0.

1.

6. The method for preparing the aromatic ester electrochromic material XEDOT-2 with helical bispropyldioxythiophene as the core according to claim 2, characterized in that: In the synthesis method, the molar ratio of the intermediate 2, 3,5-bis(methoxycarbonyl)phenylboronic acid, potassium carbonate and tetrakis(triphenylphosphine)palladium in step (4) is 1:6:18:0.

1.

7. Use of the two aromatic ester electrochromic materials with helical bispropyldioxythiophene as the core as described in claim 1 in the preparation of an all-in-one liquid electrochromic device.

8. The use according to claim 7, characterized in that: The all-in-one liquid electrochromic device is composed of two pieces of ITO conductive glass and an all-in-one liquid electrochromic electrolyte, and the specific steps are as follows: (1) Cutting and cleaning the ITO glass, and then performing ozone treatment; (2) Using a sarling film, two pieces of ITO glass of the same size are bonded together by a press machine, wherein the two pieces of ITO glass are staggered by a certain distance, and the cavity of the all-in-one liquid electrochromic device is completed; (3) fully replacing the air in the cavity of the all-in-one liquid electrochromic device with nitrogen; (4) Weigh 0.05 M of aromatic ester electrochromic material, 0.05 M of ferrocene and 0.5 M of tetrabutylammonium tetrafluoroborate and dissolve them in 0.1 mL of N-methylpyrrolidone to prepare the all-in-one liquid electrochromic device electrolyte; (5) injecting the prepared all-in-one liquid electrochromic electrolyte into the cavity of the all-in-one liquid electrochromic device through a pressure difference; (6) Use UV curing glue to seal the device.

9. The use according to claim 8, characterized in that: (1) In step (2), the Surlyn film needs to be attached to the three sides of the ITO conductive glass, and a small hole needs to be left on the other side to facilitate the injection of the electrolyte of the all-in-one electrochromic device; (2) The size of the cavity of the sarin membrane in step (2) is 1.4×1.7 cm 2 ; (3) In step (2), the press is pressed at 0.1 MPa and 130° C. for 50 seconds; (4) The volume of electrolyte filled into the all-in-one liquid electrochromic device at one time is 0.05 mL.

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