Preparation Method and Application of a Thin Film Material Based on a Naphthalene Diisoindoline Dithiazole Receptor Structure

Abstract

The present invention provides a preparation method and application of a thin film material based on a naphthalene bisthiadiazole receptor structure, relating to the technical field of organic optoelectronic materials. The preparation method is as follows: reacting 1,2,5,6-tetraaminonaphthalene hydrochloride with thionyl chloride to generate naphthalene bisthiadiazole; subjecting naphthalene bisthiadiazole to a bromination reaction with N-bromosuccinimide to generate a brominated product NTz-2Br; reacting thiophene with tributyltin chloride to generate stannylated thiophene; performing a stille coupling reaction between stannylated thiophene and NTz-2Br to generate NTz-2T; using NTz-2T as a monomer and preparing a thin film material based on a naphthalene bisthiadiazole receptor structure by cyclic voltammetry. This thin film material has a fast response time and is an electrochromic material with great application prospects. It not only enriches the D-A-D type polymer electrochromic material system but also has great reference significance for improving the electrochromic performance of polymers.

Description

Technical Field

[0001] The present invention relates to the technical field of organic optoelectronic materials, and particularly relates to a preparation method and application of a thin film material based on a naphthalene di(benzo)thiadiazole acceptor structure. Background Art

[0002] Electrochromism refers to the phenomenon that the optical properties of a material undergo stable and reversible changes under the action of an external voltage, which macroscopically manifests as reversible changes in color and transparency. Organic electrochromic materials have been synthesized and reported in large quantities due to their advantages such as easy modification of structure, adjustable color, fast response time, and diverse processing methods. For D-A-D type polymer electrochromic materials, the electron cloud distribution between the donor and the acceptor can be regulated to adjust the monomer band gap, and finally the color and properties of the polymer can be adjusted. However, the currently commonly used acceptor structural units are limited. Therefore, developing new acceptor structural units is of great significance for improving the electrochromic performance of polymers. Through the analysis and research of the structural unit of benzothiadiazole, scientific researchers have designed and improved a new type of acceptor structural unit: naphthalene di(benzo)thiadiazole. As a new type of acceptor structure, it has the advantages of strong electron-withdrawing ability, narrow band gap, and strong planarity. However, it is currently only applied to the field of solar cells.

[0003] Therefore, how to use naphthalene di(benzo)thiadiazole as an acceptor, design and synthesize a D-A-D type molecule based on naphthalene di(benzo)thiadiazole, and prepare a D-A-D structure electrochromic material with a fast response time is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of a thin film material based on a naphthalene di(benzo)thiadiazole acceptor structure to fill the blank of D-A-D structure electrochromic materials in the prior art.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a preparation method of a thin film material based on a naphthalene di(benzo)thiadiazole acceptor structure, including the following steps:

[0007] 1) React 1,2,5,6-tetraaminonaphthalene hydrochloride with thionyl chloride to generate naphthalene di(benzo)thiadiazole;

[0008] 2) Subject the naphthalene di(benzo)thiadiazole generated in step 1) to a bromination reaction with N-bromosuccinimide to generate a brominated product NTz-2Br;

[0009] 3) React thiophene with tributyltin chloride to generate tinated thiophene;

[0010] 4) React the tinated thiophene generated in step 3) with NTz-2Br generated in step 2) through a Stille coupling reaction to produce NTz-2T;

[0011] 5) Use NTz-2T as a monomer and prepare a thin film material based on the naphthalenedithieno[3,2-b:2',3'-d]thiophene receptor structure by cyclic voltammetry.

[0012] Preferably, an organic solvent needs to be added to the reaction in step 1), and the types of organic solvents include pyridine;

[0013] The addition ratio of 1,2,5,6-tetraaminonaphthalene hydrochloride, thionyl chloride and the organic solvent is 0.8 g to 1.2 g: 0.75 to 1.0 mL: 20 to 30 mL;

[0014] The reaction time is 2 to 4 h, and the temperature is 70 to 80 °C;

[0015] The reaction is carried out under a protective atmosphere, and the protective atmosphere includes a nitrogen atmosphere or an argon atmosphere.

[0016] Preferably, the steps of the bromination reaction in step 2) are as follows: Add naphthalenedithieno[3,2-b:2',3'-d]thiophene and concentrated sulfuric acid to a reaction vessel, and add N-bromosuccinimide in 2 to 4 portions within the first 1 h, heat under reflux, and replenish N-bromosuccinimide and concentrated sulfuric acid on the second day and the third day respectively.

[0017] Preferably, the initial addition amounts of the naphthalenedithieno[3,2-b:2',3'-d]thiophene and the concentrated sulfuric acid are 1 g: 20 to 30 mL;

[0018] The total amount of N-bromosuccinimide added in 2 to 4 portions within the first 1 h and the molar ratio of naphthalenedithieno[3,2-b:2',3'-d]thiophene is 2 to 2.5: 1;

[0019] The molar ratios of the N-bromosuccinimide replenished on the second day and the third day to naphthalenedithieno[3,2-b:2',3'-d]thiophene are independently 0.8 to 1: 1; the addition ratios of the concentrated sulfuric acid replenished on the second day and the third day to naphthalenedithieno[3,2-b:2',3'-d]thiophene are independently 3 to 10 mL: 1 g;

[0020] The time of the heat reflux is 65 to 75 h; the temperature is 60 to 70 °C;

[0021] The bromination reaction is carried out under light-shielded conditions.

[0022] Preferably, the steps of the reaction in step 3) are as follows: Dissolve thiophene in tetrahydrofuran, then dropwise add a n-hexane solution of n-butyllithium, keep the system temperature static after the addition is completed, and then add tributyltin chloride, and naturally rise to room temperature and stir.

[0023] Preferably, the system temperature of the n-hexane solution to which n-butyllithium is added dropwise is -75°C to -80°C; the standing time for maintaining the system temperature is 1 to 2 h;

[0024] The molar ratio of thiophene, n-butyllithium, and tributyltin chloride is 1:0.95 to 1.05:1.1 to 1.3; the addition ratio of tetrahydrofuran to thiophene is 10 to 15 mL:1 g; the molar ratio of n-butyllithium to n-hexane is 1:1.4 to 1.8; the stirring time is 8 to 14 h;

[0025] The reaction is carried out under a protective atmosphere, and the protective atmosphere includes a nitrogen atmosphere or an argon atmosphere.

[0026] Preferably, the steps of the stille coupling reaction in step 4) are as follows: Mix NTz-2Br, tinated thiophene, tetrakis(triphenylphosphine)palladium, and N,N-dimethylformamide, and heat to reflux.

[0027] Preferably, the molar ratio of NTz-2Br to tinated thiophene is 1:2.7 to 3; the addition ratio of N,N-dimethylformamide, tetrakis(triphenylphosphine)palladium, and NTz-2Br is 90 to 110 mL:15 to 25 mg:1 g;

[0028] The temperature of the heating reflux is 110 to 130°C, and the time is 10 to 14 h;

[0029] The reaction is carried out under a protective atmosphere, and the protective atmosphere includes a nitrogen atmosphere or an argon atmosphere.

[0030] Preferably, the preparation method in step 5) is as follows: Dissolve NTz-2T in dichloromethane, add tetrabutylammonium hexafluorophosphate, and electrochemically polymerize into a film by cyclic voltammetry;

[0031] Among them, the scanning rate is 90 to 110 mV / s, the voltage range is 0 to 1.5 V, and the number of cycles is 8 to 12;

[0032] The addition ratio of NTz-2T, tetrabutylammonium hexafluorophosphate, and dichloromethane is 0.8 to 2 mmol:0.08 to 0.2 mol:1 L.

[0033] Another object of the present invention is to provide an application of a thin film material based on a naphthalenedithiadiazole acceptor structure prepared by the above preparation method in D-A-D type electrochromic materials.

[0034] The present invention has at least the following beneficial effects:

[0035] The naphthalene bis(thiadiazole) derivative benefits from the planar structure of naphthalene bis(thiadiazole). Using naphthalene bis(thiadiazole) as the acceptor and thiophene as the donor, the D-A-D structure monomer (NTz-2T) is constructed. The D-A-D structure polymer film prepared by cyclic voltammetry polymerization shows a fast response time. At 770 nm, the coloring time is 1.39 s and the fading time is 0.48 s; at 1100 nm, the coloring time is 1.50 s and the fading time is 0.58 s. It is an electrochromic material with great application prospects. This not only enriches the D-A-D type polymer electrochromic material system but also has great reference significance for improving the electrochromic performance of polymers. Description of the Drawings

[0036] Figure 1 It is the synthesis route for preparing the D-A-D type derivative NTz-2T based on the naphthalene bis(thiadiazole) receptor structure in Example 1 of the present invention;

[0037] Figure 2 It is the cyclic voltammetry polymerization curve of the thin film material based on the naphthalene bis(thiadiazole) receptor structure prepared in Example 1 of the present invention;

[0038] Figure 3 It is the ultraviolet-visible absorption spectrum of the thin film material based on the naphthalene bis(thiadiazole) receptor structure prepared in Example 1 of the present invention under different voltages;

[0039] Figure 4 It is the response time of the thin film material based on the naphthalene bis(thiadiazole) receptor structure prepared in Example 1 of the present invention at different wavelengths. Detailed Embodiments

[0040] The present invention provides a preparation method for a thin film material based on a naphthalene bis(thiadiazole) receptor structure, including the following steps:

[0041] 1) React 1,2,5,6-tetraaminonaphthalene hydrochloride with thionyl chloride to generate naphthalene bis(thiadiazole);

[0042] 2) Subject the naphthalene bis(thiadiazole) generated in step 1) to a bromination reaction with N-bromosuccinimide to generate the brominated product NTz-2Br;

[0043] 3) React thiophene with tributyltin chloride to generate stannylated thiophene;

[0044] 4) Subject the stannylated thiophene generated in step 3) to a Stille coupling reaction with NTz-2Br generated in step 2) to generate NTz-2T;

[0045] 5) Use NTz-2T as a monomer and prepare a thin film material based on a naphthalene bis(thiadiazole) receptor structure by cyclic voltammetry.

[0046] In the present invention, an organic solvent needs to be added to the reaction in step 1), and the types of the organic solvent include pyridine;

[0047] The addition ratio of 1,2,5,6 - tetraaminonaphthalene hydrochloride, thionyl chloride and the organic solvent is preferably 0.8 g - 1.2 g: 0.75 - 1.0 mL: 20 - 30 mL, more preferably 0.9 g - 1.1 g: 0.8 - 0.95 mL: 22 - 28 mL, and even more preferably 1 g - 1.1 g: 0.85 - 0.9 mL: 24 - 26 mL;

[0048] The reaction time is preferably 2 - 4 h, more preferably 2.5 - 3.5 h, and even more preferably 2.8 - 3.2 h; the temperature is preferably 70 - 80 °C, more preferably 72 - 78 °C, and even more preferably 74 - 76 °C;

[0049] The reaction is carried out under a protective atmosphere, and the protective atmosphere includes a nitrogen atmosphere or an argon atmosphere.

[0050] In the present invention, after the reaction in step 1), there is also a post - treatment step: the reaction system is extracted with a solvent, the separated organic phase is concentrated, and after column chromatography separation, the solvent is removed by rotary evaporation to obtain naphthalene di - benzothiadiazole (NTz);

[0051] The solvent used for extraction is preferably dichloromethane and water, and the volume ratio of dichloromethane to water is 1:1 - 2, more preferably 1:1.5; the number of extraction times is preferably 2 - 4 times, more preferably 3 times; the desiccant used for water removal is preferably anhydrous sodium sulfate; the mobile phase used for column chromatography separation is preferably petroleum ether and dichloromethane, and the volume ratio of petroleum ether to dichloromethane is preferably 1 - 2:1, more preferably 1.5:1;

[0052] The structural formula of naphthalene di - benzothiadiazole (NTz) is as follows:

[0053]

[0054] In the present invention, the steps of the bromination reaction in step 2) are as follows: add naphthalene di - benzothiadiazole and concentrated sulfuric acid into a reaction vessel, and preferably add N - bromosuccinimide in 2 - 4 portions within the first 1 h, more preferably 3 portions; then carry out heating under reflux, and add N - bromosuccinimide and concentrated sulfuric acid respectively on the second day and the third day.

[0055] In the present invention, the initial addition amounts of the naphthalene di - benzothiadiazole and the concentrated sulfuric acid are preferably 1 g: 20 - 30 mL, more preferably 1 g: 22 - 28 mL, and even more preferably 1 g: 24 - 26 mL;

[0056] The molar ratio of the total amount of N-bromosuccinimide added in portions within the first 1 h to naphthalenedithieno[3,2-b:2',3'-d]thiophene is preferably 2 - 2.5:1, more preferably 2.1 - 2.4:1, and even more preferably 2.2 - 2.3:1;

[0057] The molar ratio of N-bromosuccinimide added separately on the second day and the third day to naphthalenedithieno[3,2-b:2',3'-d]thiophene is independently preferably 0.8 - 1:1, more preferably 0.9:1; The addition ratio of concentrated sulfuric acid added separately on the second day and the third day to naphthalenedithieno[3,2-b:2',3'-d]thiophene is independently preferably 3 - 10 mL:1 g, more preferably 4 - 9 mL:1 g, and even more preferably 6 - 8 mL:1 g;

[0058] The time of the heating reflux is preferably 65 - 75 h, more preferably 68 - 74 h, and even more preferably 72 h; The temperature is preferably 60 - 70 °C, more preferably 62 - 68 °C, and even more preferably 64 - 66 °C;

[0059] The bromination reaction is carried out under light-shielded conditions.

[0060] In the present invention, after the reaction in step 2), a post-treatment step is further included: after the reaction is completed, the reaction system is poured into ice water, an orange-red solid is precipitated, separated by suction filtration, washed and dried to obtain the bromination product NTz-2Br;

[0061] The washing process is preferably carried out by washing successively with deionized water, ethanol and tetrahydrofuran;

[0062] The structural formula of the bromination product NTz-2Br is as follows:

[0063]

[0064] In the present invention, the steps of the reaction in step 3) are as follows: thiophene is dissolved in tetrahydrofuran, then a n-hexane solution of n-butyllithium is added dropwise. After the addition is completed, the system temperature is kept static, and then tributyltin chloride is added, and the temperature is naturally raised to room temperature and stirred.

[0065] In the present invention, the system temperature for adding the n-hexane solution of n-butyllithium dropwise is preferably -75 °C to -80 °C, more preferably -76 °C to -79 °C, and even more preferably -78 °C; The time for keeping the system temperature static is preferably 1 - 2 h, more preferably 1.5 h;

[0066] The molar ratio of thiophene, n-butyllithium and tributyltin chloride is preferably 1:0.95 to 1.05:1.1 to 1.3, more preferably 1:0.98 to 1.02:1.15 to 1.25, and even more preferably 1:1:1.2; the addition ratio of tetrahydrofuran to thiophene is preferably 10 to 15 mL:1 g, more preferably 11 to 14 mL:1 g, and even more preferably 12 to 13 mL:1 g; the molar ratio of n-butyllithium to n-hexane is preferably 1:1.4 to 1.8, more preferably 1:1.5 to 1.7, and even more preferably 1:1.5 to 1.6; the stirring time is preferably 8 to 14 h, more preferably 9 to 12 h, and even more preferably 10 to 11 h;

[0067] The reaction is carried out under a protective atmosphere, and the protective atmosphere includes a nitrogen atmosphere or an argon atmosphere.

[0068] In the present invention, after the reaction in step 3), a post-treatment step is further included: after the reaction is completed, using neutral aluminum oxide as the stationary phase and dichloromethane as the mobile phase, collecting the eluate containing the target compound, and obtaining tinated thiophene after rotary evaporation to remove the solvent;

[0069] The structural formula of the tinated thiophene is as follows:

[0070]

[0071] In the present invention, the steps of the stille coupling reaction in step 4) are as follows: mixing NTz-2Br, tinated thiophene, tetrakis(triphenylphosphine)palladium and N,N-dimethylformamide, and heating to reflux.

[0072] In the present invention, the molar ratio of NTz-2Br to tinated thiophene is preferably 1:2.7 to 3, more preferably 1:2.8 to 2.9, and even more preferably 1:2.8; the addition ratio of N,N-dimethylformamide, tetrakis(triphenylphosphine)palladium and NTz-2Br is preferably 90 to 110 mL:15 to 25 mg:1 g, more preferably 95 to 105 mL:16 to 24 mg:1 g, and even more preferably 98 to 102 mL:18 to 22 mg:1 g;

[0073] The temperature of the heating reflux is preferably 110 to 130 °C, more preferably 115 to 125 °C, and even more preferably 118 to 122 °C; the time is preferably 10 to 14 h, more preferably 11 to 13 h, and even more preferably 12 h;

[0074] The reaction is carried out under a protective atmosphere, and the protective atmosphere includes a nitrogen atmosphere or an argon atmosphere.

[0075] In the present invention, after the reaction in step 4), a post-treatment step is further included: the reaction solution is cooled to room temperature and then poured into methanol, and the precipitated red solid product is collected by filtration. Column chromatography separation is carried out using petroleum ether and dichloromethane as the mobile phase, and the target product NTz-2T is obtained after rotary evaporation to remove the solvent;

[0076] The volume ratio of petroleum ether to dichloromethane in the mobile phase is preferably 3.5 - 5.5:1, more preferably 4 - 5:1, and still more preferably 4.5:1;

[0077] The structural formula of the target product NTz-2T is as follows:

[0078]

[0079] In the present invention, the preparation method in step 5) is as follows: NTz-2T is dissolved in dichloromethane, tetrabutylammonium hexafluorophosphate is added, and electrochemically polymerized into a film by cyclic voltammetry;

[0080] Among them, the scanning speed is preferably 90 - 110 mV / s, more preferably 95 - 105 mV / s, and still more preferably 98 - 102 mV / s; the voltage range is preferably 0 - 1.5 V, more preferably 0.5 - 1.2 V, and still more preferably 0.8 - 1 V; the number of cycles is preferably 8 - 12 cycles, more preferably 9 - 11 cycles, and still more preferably 10 cycles;

[0081] The addition ratio of NTz-2T, tetrabutylammonium hexafluorophosphate and dichloromethane is preferably 0.8 - 2 mmol: 0.08 - 0.2 mol: 1 L, more preferably 1 - 1.8 mmol: 0.1 - 0.18 mol: 1 L, and still more preferably 1.2 - 1.6 mmol: 0.12 - 0.16 mol: 1 L.

[0082] In the present invention, after the polymerization in step 5), the film is washed in dichloromethane to remove unpolymerized monomers or oligomers and residual electrolytes on the surface.

[0083] The technical solutions provided by the present invention will be described in detail below with reference to the examples, but they should not be construed as limiting the protection scope of the present invention.

[0084] Example 1

[0085] 1) Synthesis of NTz

[0086] Under nitrogen protection, 1,2,5,6 - tetraaminonaphthalene hydrochloride (0.567 g) was added to the reaction flask, followed by 15 mL of pyridine and thionyl chloride (0.45 mL, 2.31 mmol). The mixture was stirred and heated to 75 °C and reacted at 75 °C for 3 h. After the reaction was completed, it was cooled to room temperature, and the reaction solution was extracted twice with a mixed solution of dichloromethane and water (the volume ratio of dichloromethane to water was 1:1.5). The organic phase was collected, and the solid product was purified by a chromatography column. The mobile phase ratio used was (petroleum ether) PE:(dichloromethane) DCM = 1.5:1, and an off - white product naphthalenedithiadiazole NTz was obtained.

[0087] 1 HNMR(500MHz,CDCl3)δ(ppm):8.96(d,J=9.1Hz,1H),8.23(d,J=9.1Hz,1H).

[0088] 2) Synthesis of NTz - 2Br

[0089] Under light - shielding conditions, naphthalenedithiadiazole (0.245 g, 1 mmol) and 5 mL of concentrated sulfuric acid were successively added to the reaction flask and heated to 65 °C for 72 h. A total of 0.40 g of NBS (0.225 mmol) was added in 3 portions within the first 1 h, and 0.15 g of NBS (0.843 mmol) and 1 mL of concentrated sulfuric acid were added on the second and third days. After the reaction was completed, the reaction solution was poured into ice water, and at this time, an orange - red solid precipitated. Then the solution was filtered by suction, and the filter cake was washed successively with water, ethanol, and tetrahydrofuran, and dried to obtain the brominated product NTz - 2Br. Since the product was basically insoluble in any solvent, it could not be characterized in the next step and could be directly used for the next reaction.

[0090] 3) Synthesis of stannylated thiophene

[0091] Thiophene (1.0 g, 11.88 mmol) was dissolved in 15 mL of ultra - dry tetrahydrofuran, and then 7.42 mL of n - butyllithium in n - hexane (1.6 M) was added dropwise at - 78 °C. The mixture was stirred at the same temperature for 1 h, then tributyltin chloride (14.3 mmol) was added, and then the temperature was raised to room temperature and stirred for 12 h. After the reaction was completed, using aluminum oxide as the stationary phase and dichloromethane as the mobile phase, the eluent containing the target compound was collected, and the solvent was removed by rotary evaporation to obtain liquid stannylated thiophene.

[0092] 4) Synthesis of NTz - 2T

[0093] Under nitrogen protection, the brominated product NTz-2Br (0.31 g, 0.78 mmol), tinated thiophene (2.19 mmol), and 5 mg of tetrakis(triphenylphosphine)palladium were added to a reaction flask. 30 mL of ultradry DMF was added, and the mixture was refluxed at 120 °C for 12 h. After the reaction solution was cooled to room temperature, it was poured into methanol, and the precipitated red solid product was collected by filtration. The solid product was purified using a chromatography column with a mobile phase ratio of PE:DCM = 5:1 to obtain a red solid.

[0094] 1 HNMR (400 MHz, CDCl3) δ ppm): 9.13 (s, 2H), 8.33 (d, J = 3.7 Hz, 2H), 7.55 (d, J = 5.1 Hz, 2H), 7.29 (d, J = 4.6 Hz, 2H).

[0095] 5) Preparation of thin film materials based on naphthalene bis(dithiadiazole) receptor structure by cyclic voltammetry

[0096] NTz-2T (0.01 mmol) and tetrabutylammonium hexafluorophosphate (1 mmol) were added to a 10 mL volumetric flask, and the volume was made up with chromatographic grade dichloromethane. After ultrasonic treatment at 50 kHz for 5 min until completely dissolved, electrochemical polymerization was carried out. Using an ITO glass (0.9 * 4 cm) as the working electrode, a platinum wire as the counter electrode, and an Ag / AgCl electrode as the reference electrode, a film was formed by cyclic voltammetry with a scanning rate of 100 mV / s, a voltage range of 0 - 1.5 V, and 10 cycles. After the polymerization was completed, the electrolyte and oligomers on the film surface were washed away with chromatographic grade dichloromethane. Figure 2 It is the cyclic voltammetry polymerization curve graph for the synthesis of thin film materials. It can be seen from the figure that as the number of polymerization cycles increases, the peak current also increases, indicating that the monomer has successfully polymerized and the formed film adheres well to the surface of the ITO glass.

[0097] Example 2

[0098] 1) Synthesis of NTz

[0099] Under nitrogen protection, 1,2,5,6-tetraaminonaphthalene hydrochloride (0.8 g) was added to a reaction flask, and 20 mL of pyridine and thionyl chloride (0.75 mL) were added successively. The mixture was stirred and heated to 70 °C and reacted at 70 °C for 4 h. After the reaction was completed, it was cooled to room temperature, and the reaction solution was extracted twice with a mixed solution of dichloromethane and water (the volume ratio of dichloromethane to water was 1:1). The organic phase was collected, and the solid product was purified using a chromatography column with a mobile phase ratio of (petroleum ether) PE:(dichloromethane) DCM = 1:1 to obtain the off-white product naphthalene bis(dithiadiazole) NTz.

[0100] 2) Synthesis of NTz-2Br

[0101] Under light - shielding conditions, 1 g (4.08 mmol) of naphthalene bis - thienodiazole and 20 mL of concentrated sulfuric acid were successively added to a reaction flask, and the mixture was heated to 60 °C and reacted for 75 h. A total of 1.46 g of NBS (8.2 mmol) was added in two portions within the first 1 h, and 0.582 g of NBS (3.27 mmol) and 3 mL of concentrated sulfuric acid were added on the second and third days. After the reaction was completed, the reaction solution was poured into ice water, and at this time, an orange - red solid precipitated. Then the solution was filtered by suction, and the filter cake was washed successively with water, ethanol, and tetrahydrofuran, and dried to obtain the brominated product NTz - 2Br. Since the product is basically insoluble in any solvent, it cannot be characterized in the next step and can be directly used for the next reaction.

[0102] 3) Synthesis of stannylated thiophene

[0103] Thiophene (1.0 g, 11.88 mmol) was dissolved in 10 mL of ultra - dry tetrahydrofuran, and then 8.07 mL of n - butyllithium in hexane (1.4 M) was added dropwise at - 75 °C. The mixture was stirred at the same temperature for 1.5 h, then tributyltin chloride (13.07 mmol) was added, and then the temperature was raised to room temperature and stirred for 10 h. After the reaction was completed, using aluminum oxide as the stationary phase and dichloromethane as the mobile phase, the eluate containing the target compound was collected, and the solvent was removed by rotary evaporation to obtain liquid stannylated thiophene.

[0104] 4) Synthesis of NTz - 2T

[0105] Under nitrogen protection, the brominated product NTz - 2Br (0.402 g, 1 mmol), stannylated thiophene (2.70 mmol), and 8.04 mg of tetrakis(triphenylphosphine)palladium were added to a reaction flask, and 36.2 mL of ultra - dry DMF was added. The mixture was refluxed at 110 °C for 14 h. After the reaction solution was cooled to room temperature, it was poured into methanol, and the precipitated red solid product was collected by filtration. The solid product was purified using a chromatography column with the mobile - phase ratio of PE:DCM = 4:1 to obtain a red solid.

[0106] 1 HNMR(400MHz,CDCl3)δppm):9.13(s,2H),8.33(d,J = 3.7Hz,2H),7.55(d,J = 5.1Hz,2H),7.29(d,J = 4.6Hz,2H).

[0107] 5) Cyclic voltammetry preparation of thin - film materials based on the naphthalene bis - thienodiazole receptor structure

[0108] NTz-2T (0.008 mmol) and tetrabutylammonium hexafluorophosphate (2 mmol) were added to a 10 mL volumetric flask, and the volume was made up with chromatographic grade dichloromethane. After ultrasonic treatment at 50 kHz for 5 min and complete dissolution, electrochemical polymerization was carried out. Using an ITO glass (0.9 * 4 cm) as the working electrode, a platinum wire as the counter electrode, and an Ag / AgCl electrode as the reference electrode, film formation was carried out by cyclic voltammetry. The scanning speed was 90 mV / s, the voltage range was 0 - 1.5 V, and the number of cycles was 8. After the polymerization was completed, the electrolyte and oligomers on the film surface were washed away with chromatographic grade dichloromethane.

[0109] Example 3

[0110] 1) Synthesis of NTz

[0111] Under nitrogen protection, 1,2,5,6-tetraaminonaphthalene hydrochloride (3.60 mmol) was added to the reaction flask, and 30 mL of pyridine and thionyl chloride (1 mL) were added successively. Stir and heat to 80 °C, and react at 80 °C for 2.5 h. After the reaction was completed, it was cooled to room temperature, and the reaction solution was extracted 4 times with a mixed solution of dichloromethane and water (the volume ratio of dichloromethane to water is 1:2). The organic phase was collected, and the solid product was purified using a chromatography column. The mobile phase ratio used was (petroleum ether) PE:(dichloromethane) DCM = 2:1, and a grayish-white product naphthalenedithieno[3,2-b:2',3'-d]thiazole NTz was obtained.

[0112] 2) Synthesis of NTz-2Br

[0113] Under light-shielded conditions, naphthalenedithieno[3,2-b:2',3'-d]thiazole (1.00 g, 4.08 mmol) and 30 mL of concentrated sulfuric acid were successively added to the reaction flask and heated to 70 °C for reaction for 65 h. A total of 1.81 g of NBS (10.17 mmol) was added in 4 portions within the first 1 h, and 0.726 g of NBS (4.08 mmol) and 10 mL of concentrated sulfuric acid were added on the second and third days. After the reaction was completed, the reaction solution was poured into ice water, and at this time, an orange-red solid precipitated. Then the solution was filtered by suction, and the filter cake was washed successively with water, ethanol, and tetrahydrofuran, and dried to obtain the brominated product NTz-2Br. Since the product was basically insoluble in any solvent, it could not be characterized in the next step and could be directly used for the next reaction.

[0114] 3) Synthesis of stannylated thiophene

[0115] Thiophene (1 g, 11.88 mmol) was dissolved in 10 mL of ultra-dry tetrahydrofuran, and then 6.93 mL of n-butyllithium in hexane (1.8 M) was added dropwise at -80 °C. The mixture was stirred at the same temperature for 2 h, and then tributyltin chloride (15.4 mmol) was added. Subsequently, the temperature was raised to room temperature and stirred for 14 h. After the reaction, using aluminum oxide as the stationary phase and dichloromethane as the mobile phase, the eluate containing the target compound was collected, and the solvent was removed by rotary evaporation to obtain liquid tinated thiophene.

[0116] 4) Synthesis of NTz-2T

[0117] Under nitrogen protection, the brominated product NTz-2Br (0.402 g, 1 mmol), tinated thiophene (3.0 mmol), and 10.05 mg of tetrakis(triphenylphosphine)palladium were added to a reaction flask. Then 44.22 mL of ultra-dry DMF was added, and the mixture was refluxed at 130 °C for 10 h. After the reaction solution was cooled to room temperature, it was poured into methanol, and the precipitated red solid product was collected by filtration. The solid product was purified using a chromatography column with the mobile phase ratio of PE:DCM = 5.5:1 to obtain a red solid.

[0118] 5) Preparation of thin film materials based on naphthalene bis(dithiadiazole) acceptor structure by cyclic voltammetry

[0119] NTz-2T (0.02 mmol) and tetrabutylammonium hexafluorophosphate (0.8 mmol) were added to a 10 mL volumetric flask and made up to the mark with chromatographic grade dichloromethane. After ultrasonic treatment at 50 kHz for 5 min until completely dissolved, electrochemical polymerization was carried out. Using an ITO glass (0.9*4 cm) as the working electrode, a platinum wire as the counter electrode, and an Ag / AgCl electrode as the reference electrode, a film was formed by cyclic voltammetry with a scanning rate of 110 mV / s, a voltage range of 0 - 1.5 V, and 12 cycles. After the polymerization, the electrolyte and oligomers on the film surface were washed away with chromatographic grade dichloromethane.

[0120] Performance testing

[0121] Tetrabutylammonium hexafluorophosphate (0.387 g, 1 mmol) was added to a 10 mL volumetric flask and made up to the mark with chromatographic grade acetonitrile, which was used as the blank solution. The ITO glass covered with the thin film material based on the naphthalene bis(dithiadiazole) acceptor structure prepared in Example 1 was used as the working electrode, a platinum plate as the counter electrode, and an Ag / AgCl electrode as the reference electrode. Electrochemical, optical, and electrochromic performance tests were carried out in combination with a UV-visible spectrophotometer.

[0122] Figure 3It is the ultraviolet-visible absorption spectrogram of the thin film material under different voltages. As can be seen from the figure: when 0V voltage is applied to the thin film material, it shows the highest absorption peak at 570nm, and the thin film appears purple at this time; while when 1.5V voltage is applied, it achieves full absorption in the visible light range, and the thin film appears black at this time.

[0123] Figure 4 It is the response time of the thin film material based on the naphthalene di[1,2-c:5,4-c']dithiophene acceptor structure prepared in Example 1 of the present invention at different wavelengths. As can be seen from the figure: due to the planar structure of naphthalene di[1,2-c:5,4-c']dithiophene, the thin film shows a relatively fast response time. At 770nm, the coloring time is 1.39s and the fading time is 0.48s. At 1100nm, the coloring time is 1.50s and the fading time is 0.58s. It is a new type of electrochromic material with great application prospects.

[0124] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a thin film material based on a naphthalene di(benzo)thiadiazole receptor structure, characterized in that, It includes the following steps: 1) React 1,2,5,6-tetraaminonaphthalene hydrochloride with thionyl chloride to form naphthalene bisthiadiazole; 2) Perform a bromination reaction on the naphthalene bisthiadiazole formed in step 1) with N-bromosuccinimide to form a brominated product NTz-2Br; 3) React thiophene with tributyltin chloride to form stannylated thiophene; 4) Perform a Stille coupling reaction on the stannylated thiophene formed in step 3) with the NTz-2Br formed in step 2) to form NTz-2T; 5) Use NTz-2T as a monomer and prepare a thin film material based on the naphthalene bisthiadiazole receptor structure by cyclic voltammetry.

2. The method for preparing a thin film material based on a naphthalene di(benzo)thiadiazole receptor structure according to claim 1, characterized in that, An organic solvent needs to be added in the reaction described in step 1), and the types of organic solvents include pyridine; The addition ratio of 1,2,5,6-tetraaminonaphthalene hydrochloride, thionyl chloride and the organic solvent is 0.8 g - 1.2 g: 0.75 - 1.0 mL: 20 - 30 mL; The time of the reaction is 2 - 4 h, and the temperature is 70 - 80 °C; The reaction is carried out under a protective atmosphere, and the protective atmosphere includes a nitrogen atmosphere or an argon atmosphere.

3. The method for preparing a thin film material based on a naphthalene di(benzo)thiadiazole receptor structure according to claim 1 or 2, characterized in that, The steps of the bromination reaction described in step 2) are as follows: Add naphthalene bisthiadiazole and concentrated sulfuric acid to a reaction vessel, add N-bromosuccinimide in 2 - 4 portions within the first 1 h, heat under reflux, and supplement N-bromosuccinimide and concentrated sulfuric acid on the second day and the third day respectively.

4. The method for preparing a thin film material based on a naphthalene di(benzo)thiadiazole receptor structure according to claim 3, characterized in that, The initial addition amounts of the naphthalene bisthiadiazole and concentrated sulfuric acid are 1 g: 20 - 30 mL; The total amount of N-bromosuccinimide added in 2 - 4 portions within the first 1 h and the molar ratio of naphthalene bisthiadiazole is 2 - 2.5: 1; The molar ratio of the N-bromosuccinimide supplemented on the second day and the third day to naphthalene bisthiadiazole is independently 0.8 - 1: 1; the addition ratio of the concentrated sulfuric acid supplemented on the second day and the third day to naphthalene bisthiadiazole is independently 3 - 10 mL: 1 g; The time of the heating under reflux is 65 - 75 h; the temperature is 60 - 70 °C; The bromination reaction is carried out under light-shielded conditions.

5. The method for preparing a thin film material based on a naphthalene di(benzo)thiadiazole receptor structure according to claim 3, characterized in that, The steps of the reaction described in step 3) are as follows: Dissolve thiophene in tetrahydrofuran, then dropwise add a n-hexane solution of n-butyllithium. After the addition is completed, keep the system temperature static, and then add tributyltin chloride, and naturally rise to room temperature and stir.

6. The method for preparing a thin film material based on a naphthalene di(benzo)thiadiazole receptor structure according to claim 5, characterized in that, The system temperature for dropping the n-hexane solution of n-butyllithium is -75 °C - -80 °C; the time for keeping the system temperature static is 1 - 2 h; The molar ratio of thiophene, n-butyllithium and tributyltin chloride is 1: 0.95 - 1.05: 1.1 - 1.3; the addition ratio of tetrahydrofuran and thiophene is 10 - 15 mL: 1 g; the molar ratio of n-butyllithium and n-hexane is 1: 1.4 - 1.8; the stirring time is 8 - 14 h; The reaction is carried out under a protective atmosphere, and the protective atmosphere includes a nitrogen atmosphere or an argon atmosphere.

7. The method for preparing a thin film material based on a naphthalene di(benzo)thiadiazole receptor structure according to claim 1, 2 or 5, characterized in that, The steps of the Stille coupling reaction described in step 4) are as follows: Mix NTz-2Br, stannylated thiophene, tetrakis(triphenylphosphine)palladium and N,N-dimethylformamide, and heat under reflux.

8. The method for preparing a thin film material based on a naphthalene di(benzo)thiadiazole receptor structure according to claim 7, characterized in that, The molar ratio of NTz-2Br to tinated thiophene is 1:2.7 - 3; the addition ratio of N,N-dimethylformamide, tetrakis(triphenylphosphine)palladium and NTz-2Br is 90 - 110 mL:15 - 25 mg:1 g; The temperature of the heating reflux is 110 - 130 °C and the time is 10 - 14 h; The reaction is carried out under a protective atmosphere, and the protective atmosphere includes a nitrogen atmosphere or an argon atmosphere.

9. The preparation method of a thin film material based on a naphthalene di[1,2,5]thiadiazole acceptor structure according to claim 7, wherein, The preparation method described in step 5) is as follows: NTz-2T is dissolved in dichloromethane, tetrabutylammonium hexafluorophosphate is added, and a film is electrochemically polymerized by cyclic voltammetry; Among them, the scanning speed is 90 - 110 mV / s, the voltage range is 0 - 1.5 V, and the number of cycling circles is 8 - 12; The addition ratio of NTz-2T, tetrabutylammonium hexafluorophosphate and dichloromethane is 0.8 - 2 mmol:0.08 - 0.2 mol:1 L.

10. Application of the thin film material based on a naphthalene di[1,2,5]thiadiazole acceptor structure prepared by the preparation method according to any one of claims 1 to 9 in D-A-D type electrochromic materials.

Images