A bis-thiophene derivative, a preparation method and application thereof, and an electrochromic film and a preparation method thereof

Abstract

This invention relates to the field of electrochromic thin film technology, and more particularly to a dithiophene derivative, its preparation method, and its application, as well as an electrochromic thin film and its preparation method. This invention involves reacting dithiophene with tributyltin chloride to generate tin-modified dithiophene, reacting dithiophene with isopropanol pinacol boronic acid ester to generate boron-modified dithiophene, and then reacting the tin-modified or boron-modified dithiophene with 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene to generate 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene. This product is then reacted with dimethylboron hydride generated from lithium aluminum hydride and dimethoxyethane to finally obtain the dithiophene derivative. This derivative can be applied in electrochromic thin films. This invention successfully prepares an electrochromic thin film with fast response and fluoride ion detection capability by electrochemically polymerizing the dithiophene derivative.

Description

Technical Field

[0001] This invention relates to the field of electrochromic thin film technology, and in particular to a dithiophene derivative, its preparation method and application, as well as an electrochromic thin film and its preparation method. Background Technology

[0002] Electrochromism refers to the change in optical absorption in the visible-near-infrared region of a material under the influence of an applied voltage, due to the injection and de-charge of charges, accompanied by the doping and de-doping of electrolyte ions. Macroscopically, this manifests as a reversible change in color and transmittance. Electrochromic materials, as a novel type of functional material, have gradually attracted widespread attention.

[0003] Organic conductive polymer electrochromic materials, as an important component, have faced challenges in further development and application due to slow response times, as research has deepened. To accelerate the response time of conductive polymer electrochromic materials, a common strategy is to control the polymer's aggregated structure. Currently, a method to shorten the response time is to introduce long alkoxy chains to construct a loosely packed structure, thereby providing more migration channels. Tricoordinated boron, due to its empty p orbitals which readily combine with fluoride ions to form a stable octahedral structure, is widely used in fluoride ion sensors. Therefore, how to utilize these properties to provide a dimethyl boron-long alkoxy functional side chain and apply it to an electrochromic thin film, enabling both improved response speed and fluoride ion detection, has become a pressing technical problem in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a dithiophene derivative, its preparation method and application, and an electrochromic thin film and its preparation method, so as to solve the problems existing in the prior art.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a dithiophene derivative having the following structure:

[0007]

[0008] This invention also provides a method for preparing the above-mentioned dithiophene derivative, comprising the following steps:

[0009] (1) Preparation of 1,4-bidithiophene-2,5-bis-(6-hexynyl)-benzene:

[0010] Option 1: (a) In a protective atmosphere, dithiophene, tetrahydrofuran, n-butyllithium solution and tributyltin chloride are mixed and reacted to obtain dithiophene tin oxide;

[0011] (b) In a protective atmosphere, tin-dithiophene, 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene, tetra(triphenylphosphine)palladium and N,N-dimethylformamide were mixed and reacted to obtain 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene;

[0012] Scheme 2: (I) Under a protective atmosphere, dithiophene, tetrahydrofuran, n-butyllithium solution and isopropanol pinacol boronic acid ester are mixed and reacted to obtain boron esterified dithiophene;

[0013] (II) In a protective atmosphere, boron-esterified dithiophene, 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene, potassium carbonate, tetra(triphenylphosphine)palladium, water and dioxane are mixed and reacted to obtain 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene.

[0014] (2) Preparation of dithiophene derivatives:

[0015] (A) Under a protective atmosphere, a solution of lithium aluminum hydride in dimethoxyethane, a solution of boron dimethyl fluoride in dimethoxyethane, and benzene are mixed and reacted to obtain boron dimethyl fluoride.

[0016] (B) The dimethylboron hydrogenate, 1,4-didithiophene-2,5-bis-(6-hexynyl)-benzene and tetrahydrofuran are mixed and reacted to obtain the didithiophene derivative.

[0017] Preferably, in step (a), the ratio of tetrahydrofuran to dithiophene is 1–5 mL: 1 mmol; the molar ratio of n-butyllithium to dithiophene is 0.95–1.1:1; the molar ratio of tributyltin chloride to dithiophene is 0.95–1.3:1; and the concentration of the n-butyllithium solution is 1.4–1.8 mol / L.

[0018] The reaction temperature in step (a) is 20–28°C, and the reaction time is 10–16 h.

[0019] In step (b), the molar ratio of dithiophene tin to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 2.5–4:1; the molar ratio of N,N-dimethylformamide to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 10–15 mL:1 mmol; and the molar ratio of tetra(triphenylphosphine)palladium to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 0.03–0.08:1.

[0020] The reaction temperature in step (b) is 100–140°C, and the reaction time is 10–14 h.

[0021] Preferably, in step (I), the ratio of tetrahydrofuran to dithiophene is 1-5 mL:1 mmol; the molar ratio of n-butyllithium to dithiophene is 0.95-1.1:1; the molar ratio of isopropanol pinacol boronic acid ester to dithiophene is 1-2.1:1; and the concentration of the n-butyllithium solution is 1.4-1.8 mol / L.

[0022] The reaction temperature in step (I) is 20–28°C, and the reaction time is 10–16 h.

[0023] In step (II), the molar ratio of boron-esterified dithiophene to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 2.5–4:1; the molar ratio of potassium carbonate to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 20–45:1; the molar ratio of tetra(triphenylphosphine)palladium to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 0.03–0.08:1; the volume ratio of water to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 2–8 mL:1 mmol; and the volume ratio of dioxane to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 5–10 mL:1 mmol.

[0024] The reaction temperature in step (II) is 100–140°C, and the reaction time is 10–14 h.

[0025] Preferably, in step (A), the molar ratio of lithium aluminum hydride to dimethyl boron fluoride is 1:3-5; the molar ratio of dimethoxyethane to lithium aluminum hydride in the lithium aluminum hydride dimethoxyethane solution is 4-10 mL:1 mmol; the molar ratio of dimethoxyethane to dimethyl boron fluoride in the dimethoxyethane solution is 800-850 mL:1 mol; and the molar ratio of benzene to dimethyl boron fluoride is 20-30 mL:123.09 mmol.

[0026] The reaction in step (A) is carried out at a temperature of 20–28°C for 1–3 hours.

[0027] Preferably, in step (B), the molar ratio of hydrogenated dimethylboron to 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene is 1:3 to 5; and the molar ratio of tetrahydrofuran to 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene is 45 to 60 mL: 1 g.

[0028] The reaction in step (B) is carried out at a temperature of 30–50°C for 60–70 h.

[0029] The present invention also provides the application of the above-mentioned dithiophene derivatives in electrochromic thin films and fluoride ion detection.

[0030] The present invention also provides an electrochromic film, wherein the polymer monomer of the electrochromic film is the above-mentioned dithiophene derivative.

[0031] The present invention also provides a method for preparing the above-mentioned electrochromic thin film, comprising the following steps:

[0032] An electrochromic film was obtained by mixing a dithiophene derivative, tetrabutylammonium hexafluorophosphate, and an electrolytic solvent and then performing electrochemical polymerization.

[0033] Preferably, the ratio of tetrabutylhexafluorophosphate to electrolytic solvent is 0.08–0.2 mol: 1 L; and the ratio of dithiophene derivative to electrolytic solvent is 0.8–2 mmol: 1 L.

[0034] The electrolytic solvent comprises dichloromethane and acetonitrile; the volume ratio of dichloromethane to acetonitrile is 5-8:2-4;

[0035] The electrochemical polymerization was performed at a scan rate of 90–110 mV / s, a voltage range of 0–1.4 V, and a cycle count of 8–12.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] This invention utilizes dithiophene as the electropolymerizable group, with a long alkoxy functional side chain containing a dimethyl boron unit attached to the side chain, to prepare a novel dithiophene derivative (DTFDT-BMes) via a one-pot method. Electrochromic films based on DTFDT-BMes are then prepared using cyclic voltammetry. Benefiting from the dithiophene-benzene-dithiophene backbone structure, the molecular structure exhibits strong planarity, thereby enhancing molecular conjugation and resulting in a faster response speed for the polymer film. Simultaneously, the alkoxy functional side chain containing the dimethyl boron unit not only makes the polymer packing more loose but also enables the polymer film to detect fluoride ions. Specifically, the coloring time at 490 nm is 6.21 s, and the fading time is 1.45 s; at 735 nm, the coloring time is 2.07 s, and the fading time is 1.7 s. Furthermore, its UV-Vis absorption spectrum exhibits significantly different absorptions at different fluoride ion concentrations, making it a novel multifunctional material with great potential. Attached Figure Description

[0038] Figure 1 The mass spectrum of the dithiophene derivative prepared in Example 1 of this invention;

[0039] Figure 2 This is a cyclic voltammetric polymerization curve of the dithiophene derivative prepared in Example 1 of the present invention;

[0040] Figure 3 The following are the ultraviolet-visible absorption spectra of the electrochromic thin film prepared in Example 1 of this invention under different voltages;

[0041] Figure 4 The response time diagram of the electrochromic thin film prepared in Example 1 of the present invention at 490 nm wavelength is shown.

[0042] Figure 5 The response time diagram of the electrochromic thin film prepared in Example 1 of the present invention at 735 nm wavelength is shown.

[0043] Figure 6 The image shows the UV-Vis absorption spectra of the electrochromic thin film prepared in Example 1 of this invention at different fluoride ion concentrations. Detailed Implementation

[0044] This invention provides a dithiophene derivative having the following structure:

[0045]

[0046] This invention also provides a method for preparing the above-mentioned dithiophene derivative, comprising the following steps:

[0047] (1) Preparation of 1,4-bidithiophene-2,5-bis-(6-hexynyl)-benzene:

[0048] Option 1: (a) In a protective atmosphere, dithiophene, tetrahydrofuran, n-butyllithium solution and tributyltin chloride are mixed and reacted to obtain dithiophene tin oxide;

[0049] (b) In a protective atmosphere, tin-dithiophene, 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene, tetra(triphenylphosphine)palladium and N,N-dimethylformamide were mixed and reacted to obtain 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene;

[0050] Scheme 2: (I) Under a protective atmosphere, dithiophene, tetrahydrofuran, n-butyllithium solution and isopropanol pinacol boronic acid ester are mixed and reacted to obtain boron esterified dithiophene;

[0051] (II) In a protective atmosphere, boron-esterified dithiophene, 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene, potassium carbonate, tetra(triphenylphosphine)palladium, water and dioxane are mixed and reacted to obtain 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene.

[0052] (2) Preparation of dithiophene derivatives:

[0053] (A) Under a protective atmosphere, a solution of lithium aluminum hydride in dimethoxyethane, a solution of boron dimethyl fluoride in dimethoxyethane, and benzene are mixed and reacted to obtain boron dimethyl fluoride.

[0054] (B) The dimethylboron hydrogenate, 1,4-didithiophene-2,5-bis-(6-hexynyl)-benzene and tetrahydrofuran are mixed and reacted to obtain the didithiophene derivative.

[0055] In this invention, the structure of dithiophene in step (a) is as follows:

[0056]

[0057] The structure of the tin-modified dithiophene is shown below:

[0058]

[0059] In this invention, the ratio of tetrahydrofuran to dithiophene in step (a) is 1-5 mL:1 mmol, preferably 1.6-4 mL:1 mmol, and more preferably 2-3 mL:1 mmol;

[0060] The molar ratio of n-butyllithium to dithiophene is 0.95–1.1:1, preferably 0.98–1.05:1, and more preferably 0.99–1.01:1;

[0061] The molar ratio of tributyltin chloride to dithiophene is 0.95–1.3:1, preferably 1.13–1.26:1, and more preferably 1.15–1.2:1;

[0062] The n-butyllithium solution is a n-hexane solution of n-butyllithium, and the concentration of the n-butyllithium solution is 1.4-1.8 mol / L, preferably 1.5-1.7 mol / L, and more preferably 1.6 mol / L;

[0063] The reaction temperature in step (a) is 20–28°C, preferably 22–26°C, and more preferably 24–25°C; the reaction time is 10–16 h, preferably 11–14 h, and more preferably 12–13 h.

[0064] In this invention, step (a) is mixed in the following manner:

[0065] In a low-temperature, protective atmosphere, dithiophene and tetrahydrofuran are mixed, then n-butyllithium solution is added dropwise, followed by stirring and the addition of tributyltin chloride. The mixture is then naturally heated to the reaction temperature to carry out the reaction.

[0066] In this invention, the temperature of the low temperature is preferably -75 to -80°C, more preferably -76 to -79°C, and even more preferably -77 to -78°C.

[0067] In this invention, the protective atmosphere is the same as that in step (a), and the protective atmosphere in step (a) is nitrogen or argon, preferably nitrogen.

[0068] In this invention, the stirring time is preferably 20-40 min, more preferably 25-35 min, and even more preferably 28-32 min.

[0069] In this invention, after the reaction in step (a) is completed, a post-processing is performed, which is a sequential purification and solvent removal. The purification is carried out using a neutral alumina column. After purification, the eluent is collected, and the solvent is removed by rotary evaporation to obtain tin-dithiophene.

[0070] In this invention, the molar ratio of dithiophene tinate to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene in step (b) is 2.5 to 4:1, preferably 2.8 to 3.6:1, and more preferably 3.1 to 3.3:1;

[0071] The ratio of N,N-dimethylformamide to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 10-15 mL:1 mmol, preferably 11-14 mL:1 mmol, and more preferably 12-13 mL:1 mmol.

[0072] The molar ratio of the tetra(triphenylphosphine)palladium to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 0.03 to 0.08:1, preferably 0.04 to 0.07:1, and more preferably 0.05 to 0.06:1;

[0073] The reaction temperature in step (b) is 100–140°C, preferably 110–130°C, more preferably 115–125°C, and even more preferably 120°C; the reaction time is 10–14 h, preferably 11–13 h, more preferably 11.5–12.5 h, and even more preferably 12 h.

[0074] In this invention, the protective atmosphere in step (b) comprises nitrogen or argon, preferably nitrogen;

[0075] After the reaction in step (b) is completed, deionized water is added to the resulting mixture and extracted with dichloromethane. The mixture is then purified by column chromatography to obtain the target product 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene.

[0076] In this invention, the structure of the boron esterified dithiophene in step (I) is as follows:

[0077]

[0078] In step (I), the ratio of tetrahydrofuran to dithiophene is 1-5 mL:1 mmol, preferably 1.6-4 mL:1 mmol, and more preferably 2-3 mL:1 mmol.

[0079] The molar ratio of n-butyllithium to dithiophene is 0.95–1.1:1, preferably 0.98–1.02:1, and more preferably 0.99–1.01:1;

[0080] The molar ratio of isopropanol pinacol boronic acid ester to dithiophene is 1 to 2.1:1, preferably 1.3 to 2:1, and more preferably 1.5 to 1.8:1;

[0081] The n-butyllithium solution is a n-hexane solution of n-butyllithium, and the concentration of the n-butyllithium solution is 1.4-1.8 mol / L, preferably 1.5-1.7 mol / L, and more preferably 1.6 mol / L;

[0082] The reaction temperature in step (I) is 20–28°C, preferably 22–26°C, and more preferably 24–25°C; the reaction time is 10–16 h, preferably 11–14 h, and more preferably 12–13 h.

[0083] In this invention, step (I) is mixed in the following manner:

[0084] In a low-temperature, protective atmosphere, dithiophene and tetrahydrofuran are mixed, then n-butyllithium solution is added dropwise, and after stirring, isopropanol pinacol boronic acid ester is added. The mixture is then naturally heated to the reaction temperature to carry out the reaction.

[0085] In this invention, the temperature of the low temperature is preferably -75 to -80°C, more preferably -76 to -79°C, and even more preferably -77 to -78°C.

[0086] In this invention, the protective atmosphere is the same as the protective atmosphere in step (I), and the protective atmosphere in step (I) is nitrogen or argon, preferably nitrogen.

[0087] In this invention, the stirring time is preferably 20-40 min, more preferably 25-35 min, and even more preferably 28-32 min.

[0088] In this invention, after the reaction in step (I) is completed, the resulting reaction solution is poured into a saturated ammonium chloride solution, extracted with diethyl ether, and the organic phase is dried with anhydrous MgSO4. After removing the solvent by rotary evaporation, boron-esterified dithiophene is obtained.

[0089] In this invention, the molar ratio of boron-esterified dithiophene to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene in step (II) is 2.5 to 4:1, preferably 2.8 to 3.6:1, and more preferably 3 to 3.3:1;

[0090] The molar ratio of potassium carbonate to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 20-45:1, preferably 25-40:1, and more preferably 30-35:1;

[0091] The molar ratio of tetra(triphenylphosphine)palladium to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 0.03 to 0.08:1, preferably 0.04 to 0.07:1, and more preferably 0.05 to 0.06:1;

[0092] The ratio of water to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 2-8 mL:1 mmol, preferably 3-6 mL:1 mmol, and more preferably 4-5 mL:1 mmol;

[0093] The ratio of dioxane to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 5-10 mL:1 mmol, preferably 6-9 mL:1 mmol, and more preferably 7-8 mL:1 mmol.

[0094] The protective atmosphere in step (II) is nitrogen or argon, preferably nitrogen;

[0095] The reaction temperature in step (II) is 100–140°C, preferably 110–130°C, more preferably 115–125°C, and even more preferably 120°C; the reaction time is 10–14 h, preferably 11–13 h, and even more preferably 12 h.

[0096] After the reaction in step (II) is completed, deionized water is added and the product is extracted with dichloromethane and purified by column chromatography to obtain the target product 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene;

[0097] In this invention, the structure of 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene in steps (b) and (II) is as follows:

[0098]

[0099] In this invention, the preparation method of 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene includes the following steps: 2,5-diiodo-1,4-benzenediol, potassium carbonate, 6-chlorohexyne, and N,N-dimethylformamide are mixed and reacted under low temperature and a protective atmosphere. After the reaction, the mixture is extracted with dichloromethane and washed successively with HCl solution, deionized water, and saturated sodium chloride solution. The solvent is removed by rotary evaporation, and the crude product is purified by column chromatography to obtain 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene.

[0100] In this invention, the temperature of the low temperature is preferably -75 to -80°C, more preferably -76 to -79°C, and even more preferably -77 to -78°C.

[0101] In this invention, the protective atmosphere comprises nitrogen or argon, preferably nitrogen.

[0102] In this invention, the molar ratio of potassium carbonate, 6-chlorohexyne and 2,5-diiodo-1,4-phenylene glycol is preferably 9-11:4-5:1, more preferably 9.5-10.5:4.2-4.8:1, and even more preferably 9.8-10.2:4.4-4.6:1.

[0103] In this invention, the preferred ratio of 2,5-diiodo-1,4-phenylene glycol to N,N-dimethylformamide is 1g:60-80mL, more preferably 1g:65-75mL, and even more preferably 1g:68-72mL.

[0104] In this invention, the reaction temperature is preferably 110-130°C, more preferably 115-125°C, and even more preferably 118-122°C; the reaction time is preferably 68-75 h, more preferably 69-74 h, and even more preferably 70-73 h.

[0105] In this invention, the structure of the 1,4-bidithiophene-2,5-bis-(6-hexynyl)-benzene obtained in step (1) is shown below:

[0106]

[0107] In this invention, the molar ratio of lithium aluminum hydride to dimethyl boron fluoride in step (A) is 1:3 to 5, preferably 1:3.5 to 4.5, and more preferably 1:3.7 to 4.2;

[0108] The ratio of dimethoxyethane to lithium aluminum hydride in the dimethoxyethane solution is 4-10 mL:1 mmol, preferably 5-9 mL:1 mmol, and more preferably 6-8 mL:1 mmol.

[0109] The ratio of dimethoxyethane to dimethoxybond in the dimethoxyethane solution of dimethyl boron fluoride is 800-850 mL: 1 mol, preferably 810-840 mL: 1 mol, and more preferably 820-830 mL: 1 mol.

[0110] The ratio of benzene to dimethyl boron fluoride is 20-30 mL:123.09 mmol, preferably 22-28 mL:123.09 mmol, and more preferably 25-26 mL:123.09 mmol;

[0111] The reaction temperature in step (A) is 20–28°C, preferably 22–26°C, and more preferably 24–25°C; the reaction time is 1–3 h, preferably 1.5–2.5 h, and more preferably 2 h.

[0112] In this invention, the mixing in step (A) is carried out in the following manner: under a protective atmosphere, a solution of lithium aluminum hydride in dimethoxyethane is added dropwise to a solution of dimethyl boron fluoride in dimethoxyethane and stirred. After stirring, benzene is added to carry out the reaction in step (A) to obtain dimethyl boron fluoride.

[0113] In this invention, the protective atmosphere is nitrogen or argon, preferably nitrogen.

[0114] In this invention, the stirring time is preferably 1 to 3 hours, more preferably 1.5 to 2.5 hours, and even more preferably 1.6 to 2.4 hours.

[0115] In this invention, the molar ratio of hydrogenated dimethylboron to 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene in step (B) is 1:3 to 5, preferably 1:3.5 to 4.8, and more preferably 1:4 to 4.5;

[0116] The ratio of tetrahydrofuran to 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene is 45-60 mL:1 g, preferably 48-56 mL:1 g, and more preferably 50-55 mL:1 g.

[0117] The reaction temperature in step (B) is 30–50°C, preferably 32–45°C, more preferably 35–43°C, and even more preferably 40°C; the reaction time is 60–70 h, preferably 63–68 h, and even more preferably 65 h.

[0118] After the reaction in step (B) is completed, the mixture is cooled to room temperature and purified by column chromatography to obtain the dithiophene derivative.

[0119] In this invention, the structure of the dimethyl boron fluoride is as follows:

[0120]

[0121] In this invention, the structure of the hydride dimethyl boron is as follows:

[0122]

[0123] The present invention also provides the application of the above-mentioned dithiophene derivatives in electrochromic thin films and fluoride ion detection.

[0124] The present invention also provides an electrochromic film, wherein the polymer monomer of the electrochromic film is the above-mentioned dithiophene derivative.

[0125] The present invention also provides a method for preparing the above-mentioned electrochromic thin film, comprising the following steps:

[0126] An electrochromic film was obtained by mixing a dithiophene derivative, tetrabutylammonium hexafluorophosphate, and an electrolytic solvent and then performing electrochemical polymerization.

[0127] In this invention, the ratio of tetrabutylhexafluorophosphate to electrolytic solvent is 0.08–0.2 mol:1 L, preferably 0.09–0.1 mol:1 L; the ratio of dithiophene derivative to electrolytic solvent is 0.8–2 mmol:1 L, preferably 0.9–1.5 mmol:1 L, and more preferably 1–1.2 mmol:1 L.

[0128] The electrolytic solvent comprises dichloromethane and acetonitrile; the volume ratio of dichloromethane to acetonitrile is 5-8:2-4, preferably 6-7.5:2.5-3.5, and more preferably 7:3;

[0129] The electrochemical polymerization has a scan rate of 90–110 mV / s, preferably 95–105 mV / s, more preferably 100 mV / s, a voltage range of 0–1.4 V, preferably 0.3–1.1 V, more preferably 0.5–0.8 V, even more preferably 0.6–0.7 V, and a cycle count of 8–12, preferably 9–11, more preferably 10.

[0130] In this invention, after the electropolymerization reaction is completed, a mixed cleaning agent is used to clean the surface to remove unpolymerized monomers or oligomers and residual electrolytes, and the surface is placed in a petri dish to air dry for later use; the mixed cleaning agent contains dichloromethane and acetonitrile; the volume ratio of dichloromethane to acetonitrile is 6-8:2-4, preferably 6.5-7.5:2.5-3.5, and more preferably 7:3.

[0131] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0132] Example 1

[0133] Under nitrogen protection at -78°C, 12 mmol of dithiophene and 20 mL of ultra-dry THF were added to a reaction tube. 7.88 mL of a 1.6 mol / L n-butyllithium solution in n-hexane was then added dropwise. After stirring for 30 min, 3.1 mL of tributyltin chloride was added, and the mixture was allowed to rise naturally to room temperature (25°C) and stirred for 12 h. After the reaction was complete, the mixture was purified using a neutral alumina column. The eluent was collected, and the solvent was removed by rotary evaporation to obtain dithiophene tin.

[0134] The synthesis process of tin-based dithiophene is shown below:

[0135]

[0136] 2,5-Diiodo-1,4-benzenediol (1 g, 2.76 mmol), potassium carbonate (24.84 mmol), and 6-chlorohexyne (11.04 mmol) were dissolved in a reaction flask containing 60 mL of ultra-dry DMF at -78 °C under nitrogen protection, and reacted at 120 °C for 75 h. The reaction mixture was extracted with dichloromethane, washed twice with 55 mL of 0.8 mol / L HCl solution, and then washed once each with deionized water and saturated sodium chloride solution. The solvent was removed by rotary evaporation, and the crude product was purified by column chromatography (n-hexane:dichloromethane = 3:1) to give the target product 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene.

[0137] The synthesis process of 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is shown below:

[0138]

[0139] Under nitrogen protection, 1.92 mmol of 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene, 5.76 mmol of dithiophene tin, 0.096 mmol of Pd(PPh3)4, and 20 mL of ultra-dry DMF were added sequentially to a round-bottom flask, and the mixture was reacted at 120 °C for 12 h. After the reaction was complete, deionized water was added and the mixture was extracted with dichloromethane. The product, 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene, was purified by column chromatography.

[0140] The synthetic route for 1,4-bidithiophene-2,5-bis-(6-hexynyl)-benzene is shown below:

[0141]

[0142] Under nitrogen protection, 28 mmol of lithium aluminum hydride dissolved in 150 mL of dimethoxyethane (DME) was added dropwise to a reaction flask containing 123.09 mmol of dimethyl boron fluoride dissolved in 100 mL of DME. After stirring at 25 °C for 2 h, 22 mL of ultra-dry benzene was added, and stirring was continued for 10 min. The supernatant containing the crude product of dimethyl boron fluoride was then drawn off with a syringe. 1 mmol of 1,4-didithiophene-2,5-bis-(6-hexynyl)-benzene was dissolved in 30 mL of ultra-dry tetrahydrofuran, and then 10 mL of the supernatant containing the crude product of dimethyl boron fluoride was added. The molar ratio of dimethyl boron fluoride to 1,4-didithiophene-2,5-bis-(6-hexynyl)-benzene was 1:3. The mixture was stirred at 40 °C for 65 h. After cooling to room temperature, column chromatography was used to purify the mixture and obtain DTFDT-BMes, i.e., dimethyl fluoride derivatives.

[0143] The mass spectrum of the dithiophene derivative prepared in this embodiment is shown below. Figure 1 As shown, from Figure 1 It can be seen that the molecular ion peak of this substance is 1101.5, which is not much different from the molecular ion peak of 1099.49 simulated in ChemDraw. Therefore, DTFDT-BMes was successfully prepared in this embodiment.

[0144] The synthetic route for the dithiophene derivative is shown below:

[0145]

[0146] 0.01 mmol of DTFDT-BMes and 1 mmol of tetrabutylammonium hexafluorophosphate prepared in this embodiment were added to a 10 mL volumetric flask, and the volume was adjusted to 7 mL of chromatographic grade dichloromethane and 3 mL of chromatographic grade acetonitrile. After complete dissolution by sonication for 5 min, 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, cyclic voltammetry was employed to polymerize the film. The voltage range was 0–1.4 V, the number of cycles was 10, and the scan rate was 100 mV / s. The polymerization curve is shown below. Figure 2 As shown, from Figure 2 The peak current shows a continuous increase, indicating that the monomers underwent electropolymerization and adhered well to the ITO conductive glass surface. After polymerization, the electrolytes and oligomers on the film surface were washed away using a mixed solvent of 7 ml of chromatographic grade dichloromethane and 3 ml of chromatographic grade acetonitrile.

[0147] Example 2

[0148] The only difference from Example 1 is the preparation method of 1,4-bidithiophene-2,5-bis-(6-hexynyl)-benzene, which is as follows:

[0149] Under nitrogen protection at -78°C, 12 mmol of dithiophene and 20 mL of ultra-dry THF were added to a reaction tube. 7.88 mL of a 1.6 mol / L n-butyllithium solution in n-hexane was then added dropwise. After stirring for 30 min, 25 mmol of isopropanol pinacol boronic acid ester was added, and the mixture was allowed to rise naturally to room temperature (25°C) and stirred for 12 h. After the reaction was complete, the reaction solution was poured into a saturated ammonium chloride solution, extracted with diethyl ether, and the organic phase was dried over anhydrous MgSO4. The solvent was removed by rotary evaporation to obtain boron-esterified dithiophene.

[0150] The synthetic route for boron esterification of dithiophene is shown below:

[0151]

[0152] Under nitrogen protection, 1.92 mmol of 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene, 5.76 mmol of boron-esterified dithiophene, 40 mmol of K₂CO₃, 0.096 mmol of Pd(PPh₃)₄, 5 mL of deionized water, and 15 mL of dioxane were added sequentially to a round-bottom flask, and the mixture was reacted at 120 °C for 12 h. After the reaction was complete, deionized water was added and the mixture was extracted with dichloromethane. The product, 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene, was purified by column chromatography.

[0153] The synthetic route for 1,4-bidithiophene-2,5-bis-(6-hexynyl)-benzene is shown below:

[0154]

[0155] Test Example 1

[0156] 1 mmol of tetrabutylammonium hexafluorophosphate was added to a 10 mL volumetric flask, and the volume was adjusted to 7 mL of chromatographic grade dichloromethane and 3 mL of chromatographic grade acetonitrile to form a blank solution. The ITO glass covered with the polymer film of Example 1 was used as the working electrode, the platinum wire as the counter electrode, and the Ag / AgCl electrode as the reference electrode. The electrochemical, optical and electrochromic properties were tested by coupling with a UV-Vis spectrophotometer.

[0157] The UV-Vis absorption spectra of electrochromic films at different voltages are as follows: Figure 3 As shown, by Figure 3 It can be seen that the prepared film can change color under a voltage of 0 to 1.4V. The film is orange-yellow at 0V and gray-blue at 1.4V.

[0158] The response of the electrochromic thin film in the 490nm band is as follows Figure 4 As shown, from Figure 4It can be seen that the coloring time of the electrochromic film at 490nm is 6.21s and the fading time is 1.45s.

[0159] The response time of the electrochromic thin film in the 735nm band is as follows Figure 5 As shown, from Figure 5 It can be seen that the coloring time of the electrochromic film at 735nm is 2.07s and the fading time is 1.7s.

[0160] The UV-Vis absorption spectra of the electrochromic thin film at different fluoride ion concentrations are shown below. Figure 6 As shown, from Figure 6 It can be seen that the spectral absorption of the thin film changed significantly under different fluoride ion concentrations, indicating that it can be used in the field of fluoride ion detection.

[0161] As can be seen from the above embodiments, the present invention provides a dithiophene derivative, its preparation method and application, and an electrochromic film and its preparation method. Thanks to the novel monomer's main chain being dithiophene-benzene-dithiophene, the molecular structure exhibits strong planarity, thereby enhancing molecular conjugation and resulting in a faster response speed for the polymer film. Simultaneously, the alkoxy functional side chains containing dimethylboron units not only make the polymer stacking more loose but also enable the polymer film to detect fluoride ions. Specifically, the polymer film exhibits a coloring time of 6.21 s and a fading time of 1.45 s at 490 nm; and a coloring time of 2.07 s and a fading time of 1.7 s at 735 nm. Furthermore, its UV-Vis absorption spectrum shows significantly different absorptions at different fluoride ion concentrations, making it a novel multifunctional material with great potential.

[0162] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A dithiophene derivative, characterized in that, It has the following structure:

2. The method for preparing a dithiophene derivative according to claim 1, characterized in that, Includes the following steps: (1) Preparation of 1,4-bidithiophene-2,5-bis-(6-hexynyl)-benzene: Option 1: (a) In a protective atmosphere, dithiophene, tetrahydrofuran, n-butyllithium solution and tributyltin chloride are mixed and reacted to obtain dithiophene tin oxide; (b) In a protective atmosphere, tin-dithiophene, 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene, tetra(triphenylphosphine)palladium and N,N-dimethylformamide were mixed and reacted to obtain 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene; Scheme 2: (I) Under a protective atmosphere, dithiophene, tetrahydrofuran, n-butyllithium solution and isopropanol pinacol boronic acid ester are mixed and reacted to obtain boron esterified dithiophene; (II) In a protective atmosphere, boron-esterified dithiophene, 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene, potassium carbonate, tetra(triphenylphosphine)palladium, water and dioxane are mixed and reacted to obtain 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene. (2) Preparation of dithiophene derivatives: (A) Under a protective atmosphere, a solution of lithium aluminum hydride in dimethoxyethane, a solution of boron dimethyl fluoride in dimethoxyethane, and benzene are mixed and reacted to obtain boron dimethyl fluoride. (B) The dimethylboron hydrogenate, 1,4-didithiophene-2,5-bis-(6-hexynyl)-benzene and tetrahydrofuran are mixed and reacted to obtain the didithiophene derivative.

3. The method for preparing a dithiophene derivative according to claim 2, characterized in that, In step (a), the ratio of tetrahydrofuran to dithiophene is 1–5 mL: 1 mmol; the molar ratio of n-butyllithium to dithiophene is 0.95–1.1:1; the molar ratio of tributyltin chloride to dithiophene is 0.95–1.3:1; and the concentration of the n-butyllithium solution is 1.4–1.8 mol / L. The reaction temperature in step (a) is 20–28°C, and the reaction time is 10–16 h. In step (b), the molar ratio of dithiophene tin to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 2.5–4:1; the molar ratio of N,N-dimethylformamide to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 10–15 mL:1 mmol; and the molar ratio of tetra(triphenylphosphine)palladium to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 0.03–0.08:

1. The reaction temperature in step (b) is 100–140°C, and the reaction time is 10–14 h.

4. A method for preparing a dithiophene derivative according to claim 2 or 3, characterized in that, In step (I), the ratio of tetrahydrofuran to dithiophene is 1–5 mL: 1 mmol; the molar ratio of n-butyllithium to dithiophene is 0.95–1.1:1; the molar ratio of isopropanol pinacol boronic acid ester to dithiophene is 1–2.1:1; and the concentration of the n-butyllithium solution is 1.4–1.8 mol / L. The reaction temperature in step (I) is 20–28°C, and the reaction time is 10–16 h. In step (II), the molar ratio of boron-esterified dithiophene to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 2.5–4:1; the molar ratio of potassium carbonate to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 20–45:1; the molar ratio of tetra(triphenylphosphine)palladium to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 0.03–0.08:1; the volume ratio of water to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 2–8 mL:1 mmol; and the volume ratio of dioxane to 1,4-diiodo-2,5-bis-(6-hexynyl)-benzene is 5–10 mL:1 mmol. The reaction temperature in step (II) is 100–140°C, and the reaction time is 10–14 h.

5. The method for preparing a dithiophene derivative according to claim 4, characterized in that, In step (A), the molar ratio of lithium aluminum hydride to dimethyl boron fluoride is 1:3-5; the ratio of dimethoxyethane to lithium aluminum hydride in the lithium aluminum hydride dimethoxyethane solution is 4-10 mL:1 mmol; the ratio of dimethoxyethane to dimethyl boron fluoride in the dimethoxyethane solution is 800-850 mL:1 mol; and the ratio of benzene to dimethyl boron fluoride is 20-30 mL:123.09 mmol. The reaction in step (A) is carried out at a temperature of 20–28°C for 1–3 hours.

6. A method for preparing a dithiophene derivative according to claim 2 or 5, characterized in that, In step (B), the molar ratio of hydrogenated dimethylboron to 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene is 1:3 to 5; the molar ratio of tetrahydrofuran to 1,4-dithiophene-2,5-bis-(6-hexynyl)-benzene is 45 to 60 mL: 1 g. The reaction in step (B) is carried out at a temperature of 30–50°C for 60–70 h.

7. The application of the dithiophene derivative of claim 1 in electrochromic thin films and fluoride ion detection.

8. An electrochromic thin film, characterized in that, The polymer monomer of the electrochromic film is the dithiophene derivative as described in claim 1.

9. The method for preparing the electrochromic thin film according to claim 8, characterized in that, Includes the following steps: An electrochromic film was obtained by mixing a dithiophene derivative, tetrabutylammonium hexafluorophosphate, and an electrolytic solvent and then performing electrochemical polymerization.

10. The preparation method according to claim 9, characterized in that, The ratio of tetrabutylhexafluorophosphate to electrolytic solvent is 0.08–0.2 mol: 1 L; the ratio of dithiophene derivative to electrolytic solvent is 0.8–2 mmol: 1 L. The electrolytic solvent comprises dichloromethane and acetonitrile; the volume ratio of dichloromethane to acetonitrile is 5-8:2-4; The electrochemical polymerization was performed at a scan rate of 90–110 mV / s, a voltage range of 0–1.4 V, and a cycle count of 8–12.

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