Process for the preparation of ester-substituted polythiophenes

Abstract

The application discloses a preparation method of an ester-substituted polythiophene, and the preparation method comprises the following steps: mixing a monomer M, a palladium catalyst, a ligand, an oxidant, a base and a solvent to obtain a reaction material, reacting the reaction material at 60-150 DEG C for 12-72 hours, and purifying the reaction material to obtain the ester-substituted polythiophene. The preparation method can significantly improve the C-H / C-H coupling efficiency of the monomer, obtain the ester-substituted polythiophene, and the number average molecular weight of the ester-substituted polythiophene can be higher than 90000, and the yield can be higher than 99%. The raw materials required by the preparation method are simple and easy to obtain, the raw materials do not need to be pretreated, and the polymerization can be directly carried out, so that the use of air-sensitive reagents, toxic metal reagents and the generation of toxic by-products are avoided.

Description

Technical Field

[0001] This invention belongs to the field of conductive polymer technology, and specifically relates to a method for preparing ester-substituted polythiophene. Background Technology

[0002] Polythiophene and its derivatives possess excellent optical and electrical properties, making them important conductive polymer materials widely used in organic photovoltaics, field-effect transistors, and light-emitting diodes. Introducing ester groups into the side chains of polythiophene can effectively control its energy levels, band gap, and packing structure due to the electron-withdrawing effect and steric hindrance of the ester groups, thus affecting its optoelectronic properties and device performance. Currently, ester-substituted polythiophene is mainly prepared via classic Stille or Suzuki coupling polymerization. These polymerization methods are highly efficient and have a wide range of applicable monomers, but the need for pre-preparation of thiophene bromides and thiophene tin or borides leads to long synthetic routes, high monomer costs, and the potential generation of toxic byproducts, causing environmental pollution. Therefore, developing a more atom-economical, fewer-step, lower-cost, and more environmentally friendly polymerization method for preparing high-quality ester-substituted polythiophene remains an urgent need.

[0003] Transition metal-catalyzed direct CH / CH coupling polycondensation is a novel method for preparing conjugated polymers that has emerged in recent years. The synthesis process requires no prefunctionalization of the monomers; the polymer is obtained directly through coupling via the CH bonds in the aromatic monomers, thus avoiding the generation of toxic or harmful byproducts and exhibiting high atom economy and environmental friendliness. However, when using this method to prepare ester-substituted polythiophenes, the low activity of the CH bonds and the low CH / CH coupling efficiency result in low molecular weight polymers, typically with a number average molecular weight of less than 20,000. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing ester-substituted polythiophene.

[0005] The objective of this invention is achieved through the following technical solution.

[0006] A method for preparing ester-substituted polythiophene includes: mixing monomer M, palladium catalyst, ligand, oxidant, base and solvent to obtain a reactant; reacting the reactant at 60–150°C for 12–72 hours; purifying to obtain ester-substituted polythiophene; wherein the general structural formula of monomer M is:

[0007] Wherein, R1 is an alkyl group or an alkyl substituent.

[0008] In the above technical solution, the ratio of monomer M, palladium catalyst, ligand, oxidant and base by molar amount is 1:(0.03~0.2):(0.03~0.2):(1-4):(1-4), preferably 1:0.05:0.15:2:2.

[0009] In the above technical solution, the palladium catalyst is one or more of Pd(OAc)2, PdCl2, Herrmann's catalyst, Pd(dppf)Cl2, Pd2(dba)3, Pd(TFA)2, PdCl2(PPh3)2, Pd(OH)2, Pd(PPh3)4 and palladium on carbon;

[0010] The ligand is an organophosphorus or a terpyridine derivative;

[0011] The oxidant is one or more selected from Ag2CO3, AgF, AgOAc, Ag2O, Cu(OAc)2, Cu(OTf)2, CuCl2 and AgNO3;

[0012] The alkali is one or more selected from Na2CO3, K2CO3, Cs2CO3, NaHCO3, NaOAc, KOAc, CsOAc, and KF.

[0013] In the above technical solution, R1 is C1-C 30 Alkyl or C1-C 30 Alkyl substituents, C1-C 30 The substituents in the alkyl substituents are cycloalkyl, aryl, heteroaryl, heterocycloalkyl, hydroxyl, alkoxy, aryloxy, mercapto, alkylthio, arylthio, halogen, carbonyl, thiocarbonyl, O-carbamoyl, N-carbamoyl, O-thiocarbamoyl, N-thiocarbamoyl, C-amide, N-amide, S-sulfinamide, N-sulfinamide, C-carboxyl, O-carboxyl, cyanothio, nitro, trihalomethanesulfonyl, or silyl.

[0014] In the above technical solution, the general structural formula of the organophosphorus is as follows:

[0015] Where n is a positive integer from 1 to 4;

[0016] In the above technical solution, the general structural formula of the terpyridine derivative is as follows:

[0017] Wherein, R2 is H, C1-C 30 Alkyl, amino, hydroxyl, nitro, C1-C 30 Alkyl-substituted amino or C1-C 30 Alkyl group.

[0018] In the above technical solution, the solvent is one or a mixture of several of toluene, 1,4-dioxane, o-xylene, tetrahydrofuran, N,N-dimethylacetamide, N,N-diethylformamide, N,N-diethylacetamide, N,N-dimethylformamide, toluene, and dimethyl sulfoxide.

[0019] In the above technical solution, stirring is carried out during the reaction at 60-150°C, and the preferred reaction temperature is 80-110°C.

[0020] In the above technical solution, the concentration of monomer M in the reactant is 0.005-1 mol / L, preferably 0.1-0.5 mol / L.

[0021] In the above technical solution, the purification is Soxhlet extraction.

[0022] In the above technical solution, the Soxhlet extraction includes: dropping the liquid to be purified after the reaction into methanol to settle, filtering to obtain a crude product, extracting the crude product sequentially with methanol and n-hexane using Soxhlet extraction, then extracting with chloroform using Soxhlet extraction, collecting the chloroform extract, rotary evaporating, and drying.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. The preparation method of the present invention can obtain ester-substituted polythiophenes with different number-average molecular weights by adjusting the reaction temperature, ligand input amount, or reaction time. The raw materials required for the preparation method of the present invention are simple and readily available, do not require pretreatment, and can be directly polymerized, avoiding the use of air-sensitive reagents (such as n-butyllithium), toxic metal reagents, and the generation of toxic byproducts;

[0025] 2. This preparation method can significantly improve the CH / CH coupling efficiency of monomers. By adjusting the reaction temperature, ligand input amount, or reaction time, high molecular weight ester-substituted polythiophene can be obtained, with a number average molecular weight of up to 90,000 and a yield of up to 99%. Attached Figure Description

[0026] Figure 1 The ester-substituted polythiophene obtained in Example 3 1 H NMR spectrum;

[0027] Figure 2 The image shows the GPC effluent curve of the ester-substituted polythiophene obtained in Example 4. Detailed Implementation

[0028] The general process of the preparation method of the present invention is as follows: monomer M, palladium catalyst, ligand, oxidant, base and solvent are added to the reaction vessel, sealed, and the reaction system is kept at 60-150°C for 12-72 hours. After purification, ester-substituted polythiophene is obtained.

[0029]

[0030] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0031] In the following examples, purification was performed using Soxhlet extraction. The specific steps were as follows: 3 mL of the liquid to be purified after reaction was added dropwise to 100 mL of methanol at a rate of 1 drop per second (each drop having a volume of 0.5 mL) for sedimentation. After sedimentation for 12 hours, the product was filtered to obtain a crude product. The crude product was then sequentially extracted with methanol and n-hexane for 24 hours each using the Soxhlet extraction method to remove impurities and low molecular weight polymers. Finally, the product was extracted with chloroform using the Soxhlet extraction method until the chloroform in the Soxhlet extraction tube was colorless. The extraction was then stopped, and the chloroform extract was collected. After removing the solvent by rotary evaporation, the product was dried in a vacuum drying oven at 40°C for 12 hours to complete the purification.

[0032] The models of the instruments involved in the following embodiments are as follows:

[0033]

[0034] The following examples involve the following raw materials:

[0035]

[0036]

[0037] Example 1

[0038] Synthesis of Compound 1: 3-Thiophenecarboxylic acid (3.5 g, 27.3 mmol) was placed in a 100 mL round-bottom flask, 25 mL of chloroform was added, and the mixture was stirred to dissolve. Then, thionyl chloride (4.5 g, 37.4 mmol) was added, and the mixture was heated to 55 °C. Five drops of anhydrous DMF were added, and the mixture was reacted at 55 °C for 4 h. The reaction was stopped, cooled to room temperature, and 10 mL of n-hexane was added to the reaction solution. The mixture was allowed to stand for 10 min to allow the DMF and impurities to separate into an oil layer. The upper layer was slowly poured off, and the remaining lower layer was transferred to a round-bottom flask. The solvent was removed by rotary evaporation to obtain Compound 1. (Peter M. Rademacher, Caleb M. Woods, Qingbiao Huang, et al. Differential oxidation of two thiophene-containing regioisomers toreactive metabolites by cytochrome P450 2C9[J]. Chemical Research in Toxicology, 2012, 25: 895-903.)

[0039] Synthesis of monomer M: Octanol (3.38 g, 26.0 mmol), triethylamine (3.87 g, 38.3 mmol), and dichloromethane (20 mL) were added to a 100 mL round-bottom flask under ice-water bath and stirred until dissolved. Then, compound 1 (3.78 g, 25.8 mmol) was dissolved in 10 mL of CH₂Cl₂ and added dropwise to the round-bottom flask using a constant-pressure dropping funnel. The resulting reaction mixture was reacted at 55 °C for 6 h. The reaction was stopped, and 100 mL of dichloromethane was added to the reaction system. The system was washed twice each with 100 mL of deionized water, 100 mL of hydrochloric acid aqueous solution (5 mol / L), and 100 mL of sodium bicarbonate aqueous solution (5 mol / L). The CH2Cl2 phase was collected, dried over anhydrous sodium sulfate, and purified by column chromatography with petroleum ether / ethyl acetate (40:1, v / v) as the eluent. A colorless and transparent oily substance was obtained as monomer M (5.6 g, yield 89%). 1H NMR (400MHz, CDCl3) δ8.10(s,1H),7.53(s,1H),7.30(s,1H),4.26(d,J=13.3 Hz, 2H), 1.78-1.67 (m, 2H), 1.29 (d, J = 10.8Hz, 10H), 0.88 (d, J = 12.1Hz, 3H). (Gallelli Pratap,Tanneru Narasimhaswamy,Ponnusamy Shanmugam.Palladium(II)catalyzed arylation and methylene oxidation of 2,7-dibromo fluorenes withheteroaryl esters:Synthesis of mesogenic2-heteroaryl and 2,7-diheteroaryl-9-fluorenones[J].ChemistrySelect, 2019,4:1795-1799.)

[0040] The structural formula of the above-mentioned monomer M is as follows:

[0041]

[0042] A method for preparing ester-substituted polythiophene, comprising:

[0043] The monomers M (72 mg, 0.3 mmol), palladium acetate (3.4 mg, 0.015 mmol), 1,3-bis(diphenylphosphine)propane (12.4 mg, 0.03 mmol), Ag₂CO₃ (165.6 mg, 0.6 mmol), KOAc (58.8 mg, 0.6 mmol), and DMAc (3 mL) obtained in this embodiment were added to a thick-walled glass reaction flask. The flask was sealed and heated to 90 °C. The reaction was carried out under magnetic stirring for 48 h. The reaction was then stopped, cooled to room temperature, and Soxhlet extraction was used to obtain ester-substituted polythiophene P1 (69.3 mg, 99% yield). 1 ¹H NMR (400 MHz, CDCl₃) δ 8.19–7.55 (m, 1H), 4.21 (d, J = 69.5 Hz, 2H), 1.74 (s, 2H), 1.24 (d, J = 16.9 Hz, 11H), 0.86 (s, 3H). Number-average molecular weight M n It is 22900, PDI 2.93 (GPC, THF).

[0044] The reaction process for the synthesis of compound 1, the synthesis of monomer M, and the preparation of ester-substituted polythiophene is as follows:

[0045]

[0046] Example 2

[0047] Synthesis of monomer M: Under ice-water bath conditions, 2-butyloctanol (4.84 g, 26 mmol), triethylamine (3.87 g, 38.3 mmol), and dichloromethane (20 mL) were added to a 100 mL round-bottom flask and stirred to dissolve. Then, compound 1 (3.78 g, 25.8 mmol) from Example 1 was dissolved in 10 mL of CH2Cl2 and added dropwise to the above-mentioned round-bottom flask through a constant-pressure dropping funnel. The reaction mixture was reacted at 55 °C for 6 h. The reaction was stopped, and 100 mL of dichloromethane was added to the reaction system. The system was washed twice each with 100 mL of deionized water, 100 mL of hydrochloric acid aqueous solution (5 mol / L), and 100 mL of sodium bicarbonate aqueous solution (5 mol / L). The CH2Cl2 phase was collected, dried over anhydrous sodium sulfate, and purified by column chromatography with petroleum ether / ethyl acetate (40:1, v / v) as the eluent. A colorless and transparent oily substance was obtained as monomer M (6.3 g, yield 82%). 1 H NMR(400MHz, CDCl3) δ8.09(d,J=3.1Hz,1H),7.52(d,J=5.0Hz,1H),7.30(d,J=4 .1Hz,1H),4.17(s,2H),1.74(s,1H),1.37–1.25(m,16H),0.89(d,J=8.5Hz,7H).

[0048] The monomer M mentioned above is as follows:

[0049]

[0050] A method for preparing ester-substituted polythiophene, comprising:

[0051] The monomer M (89 mg, 0.3 mmol), palladium acetate (3.4 mg, 0.015 mmol), 1,3-bis(diphenylphosphine)propane (12.4 mg, 0.03 mmol), Ag₂CO₃ (165.6 mg, 0.6 mmol), KOAc (58.8 mg, 0.6 mmol), and DMAc (3 mL) obtained in this embodiment were added to a thick-walled glass reaction flask. The flask was sealed and heated to 90 °C, then reacted with magnetic stirring for 48 h. The reaction was stopped, cooled to room temperature, and Soxhlet extraction was performed to obtain ester-substituted polythiophene P₂ (73 mg, yield 83%). 1¹H NMR (400MHz, CDCl₃) δ 7.99–7.53 (m, 1H), 4.20 (s, 1H), 4.05 (s, 1H), 1.74 (s, 1H), 1.28 (d, J = 21.4 Hz, 16H), 0.87 (d, J = 14.4 Hz, 7H). Number-average molecular weight M n It is 48200, PDI 2.60 (GPC, THF).

[0052] The process of synthesizing monomer M from compound 1 and then preparing ester-substituted polythiophene P2 is as follows:

[0053]

[0054] Example 3

[0055] A method for preparing ester-substituted polythiophene, comprising:

[0056] Monomer M (72 mg, 0.3 mmol), Herrmann's catalyst (14.1 mg, 0.015 mmol), 1,3-bis(diphenylphosphine)propane (12.4 mg, 0.03 mmol), Ag₂CO₃ (165.6 mg, 0.6 mmol), KOAc (58.8 mg, 0.6 mmol), and DMAc (3 mL) were added to a thick-walled glass reaction flask. The flask was sealed and heated to 90 °C with magnetic stirring for 48 h. The reaction was then stopped, cooled to room temperature, and Soxhlet extraction was performed to obtain ester-substituted polythiophene P₃ (59.2 mg, 84.5% yield). 1 ¹H NMR (400MHz, CDCl₃) δ 7.96–7.57 (m, ¹H), 4.30 (s, ²H), 1.74 (s, ²H), 1.23 (d, J = 14.1 Hz, ¹¹H), 0.86 (s, ³H). Number-average molecular weight M n It is 80300, PDI 1.71 (GPC, THF).

[0057] Appendix Figure 1 The figure shows the 1H NMR spectrum of the ester-substituted polythiophene prepared in Example 3. The characteristic peaks at chemical shifts of 7.93, 7.86, and 7.60 are hydrogens on the thiophene ring of the ester-substituted polythiophene. The characteristic peaks at chemical shifts of 4.3 and 4.12 are α-hydrogens connected to the ester group. The characteristic peaks at chemical shifts of 1.74, 1.25, 1.22, and 0.86 are hydrogens from the alkyl side chain. Therefore, the structure of the ester-substituted polythiophene is correct.

[0058] The structure of monomer M in this embodiment is as follows:

[0059]

[0060] The preparation process of ester-substituted polythiophene from monomer M in this embodiment is as follows:

[0061]

[0062] Example 4

[0063] Synthesis of 4-([2,2':6',2”-bipyridine]-4'-yl)-N,N-dimethylaniline (L1) as a ligand

[0064]

[0065] Under ice-water bath conditions, 1.49 g (10 mmol) of 4-(dimethylamino)benzaldehyde and 2-acetylpyridine (2.42 g, 20 mmol) were placed in a 250 mL three-necked round-bottom flask, and 50 mL of ethanol was added and stirred to dissolve. 10 mL of potassium hydroxide aqueous solution (containing 1.32 g (20 mmol) of potassium hydroxide) was added dropwise to the flask. The mixture was reacted at 35 °C for 4 h. Then, 35 mL of ammonia (25-28%) was added to the reaction system, and the mixture was refluxed for another 7 h. The reaction was stopped, the mixture was filtered, and the filter cake was washed with cold ethanol (0 °C) and dried to obtain the crude product. Recrystallization of the crude product from ethanol yielded a yellow solid, L1 (1.48 g, 42% yield). 1 H NMR (400MHz, CDCl3) δ8.77-8.69(m,4H),8.67(d,J=8.0Hz,2H),7.92-7.83(m,4H),7.34(dd,J=7.4,5.0Hz,2H),6.86-6.79(m,2H),3.04(s,6H). (Gallelli Pratap,Tanneru Narasimhaswamy,Ponnusamy Shanmugam.Palladium(II)catalyzed arylationand methylene oxidation of 2,7-dibromo fluorenes with heteroaryl esters:synthesis of mesogenic2-heteroaryl and 2,7-diheteroaryl-9-fluorenones[J].ChemistrySelect, 2019,4:1795-1799.)

[0066] The structural formula for L1 is as follows:

[0067]

[0068] A method for preparing ester-substituted polythiophene, comprising:

[0069] Monomer M (72 mg, 0.3 mmol), palladium acetate (3.4 mg, 0.015 mmol), 4-([2,2':6',2”-bipyridine]-4'-yl)-N,N-dimethylaniline (10.6 mg, 0.03 mmol) (L1), Ag2CO3 (165.6 mg, 0.6 mmol), KOAc (58.8 mg, 0.6 mmol), and DMAc (3 mL) were added to a thick-walled glass reaction flask. The flask was sealed and heated to 90 °C with magnetic stirring for 48 h. The reaction was then stopped, cooled to room temperature, and Soxhlet extraction was performed to obtain ester-substituted polythiophene P4 (58.8 mg, yield 84%). 1 ¹H NMR (400MHz, CDCl₃) δ 7.96–7.57 (m, 1H), 4.22 (d, J = 64.2 Hz, 2H), 1.75 (s, 2H), 1.23 (d, J = 13.6 Hz, 12H), 0.91–0.78 (m, 3H). Number-average molecular weight M n It is 92600, PDI 2.37 (GPC, THF).

[0070] Appendix Figure 2 The image shows the gel permeation chromatogram of the ester-substituted polythiophene P4 prepared in Example 4. The eluent was chromatographically pure tetrahydrofuran, the flow rate was 1.0 mL / min, and the concentration of the ester-substituted polythiophene was 2 mg / mL. The working curve was calibrated using standard narrow-distribution polystyrene. The ester-substituted polythiophene with the larger molecular weight elutes from the column first; therefore, the larger the molecular weight of the ester-substituted polythiophene, the earlier its peak appears. Since the number-average molecular weight is at the peak of the distribution curve, when the peak positions are close, the earlier the peak appears, the larger its molecular weight.

[0071] The structure of monomer M in this embodiment is as follows:

[0072]

[0073] The preparation process of ester-substituted polythiophene from monomer M in this embodiment is as follows:

[0074]

[0075] Example 5

[0076] A method for preparing ester-substituted polythiophene includes: adding monomer M (72 mg, 0.3 mmol), Herrmann's catalyst (14.1 mg, 0.015 mmol), 1,3-bis(diphenylphosphine)propane (12.4 mg, 0.03 mmol), Ag₂CO₃ (165.6 mg, 0.6 mmol), KOAc (58.8 mg, 0.6 mmol), and DMAc (3 mL) to a thick-walled glass reaction flask, sealing the flask, heating to 110 °C, and reacting with magnetic stirring for 48 h. The reaction is then stopped, cooled to room temperature, and Soxhlet extraction is used to obtain ester-substituted polythiophene P5 (41.3 mg, yield 57%). 1 ¹H NMR (400MHz, CDCl₃) δ 7.96–7.56 (m, 1H), 4.30 (s, 2H), 4.12 (s, 1H), 1.74 (s, 2H), 1.25 (s, 10H), 0.86 (s, 3H). Number-average molecular weight Mn was 33,800, PDI 2.80 (GPC, THF).

[0077] The structure of monomer M in this embodiment is as follows:

[0078]

[0079] The preparation process of ester-substituted polythiophene from monomer M in this embodiment is as follows:

[0080]

[0081] Example 6

[0082] A method for preparing ester-substituted polythiophene, comprising:

[0083] Monomer M (72 mg, 0.3 mmol), palladium acetate (3.4 mg, 0.015 mmol), 1,3-bis(diphenylphosphine)propane (18.6 mg, 0.045 mmol), Ag₂CO₃ (165.6 mg, 0.6 mmol), KOAc (58.8 mg, 0.6 mmol), and DMAc (3 mL) were added to a thick-walled glass reaction flask. The flask was sealed and heated to 90 °C with magnetic stirring for 48 h. The reaction was then stopped, cooled to room temperature, and Soxhlet extraction was performed to obtain ester-substituted polythiophene P6 (54.8 mg, 76% yield). 1 ¹H NMR (400MHz, CDCl₃) δ 7.97–7.56 (m, 1H), 4.21 (d, J = 68.9 Hz, 2H), 1.74 (s, 2H), 1.22 (s, 11H), 0.86 (s, 3H). Number-average molecular weight M n It is 22500, PDI 3.26 (GPC, THF).

[0084] The structure of monomer M in this embodiment is as follows:

[0085]

[0086] The preparation process of ester-substituted polythiophene from monomer M in this embodiment is as follows:

[0087]

[0088] Example 7

[0089] A method for preparing ester-substituted polythiophene, comprising:

[0090] Monomer M (72 mg, 0.3 mmol), palladium acetate (3.4 mg, 0.015 mmol), 1,3-bis(diphenylphosphine)propane (6.2 mg, 0.015 mmol), Ag₂CO₃ (165.6 mg, 0.6 mmol), KOAc (58.8 mg, 0.6 mmol), and DMAc (3 mL) were added to a thick-walled glass reaction flask. The flask was sealed and heated to 90 °C with magnetic stirring for 48 h. The reaction was then stopped, cooled to room temperature, and Soxhlet extraction was performed to obtain ester-substituted polythiophene P7 (31 mg, 43% yield). 1 H NMR (400MHz, CDCl3) δ7.98–7.56 (m, 1H), 4.21 (d, J = 69.3Hz, 2H), 1.74 (s, 2H), 1.24 (d, J = 18.4Hz, 10H), 0.86 (s, 3H). Mn26400, PDI 3.62 (GPC, THF).

[0091] The structure of monomer M in this embodiment is as follows:

[0092]

[0093] The preparation process of ester-substituted polythiophene from monomer M in this embodiment is as follows:

[0094]

[0095] Example 8

[0096] A method for preparing ester-substituted polythiophene, comprising:

[0097] Monomer M (72 mg, 0.3 mmol), palladium chloride (2.7 mg, 0.015 mmol), bis(diphenylphosphine)methane (11.5 mg, 0.03 mmol), Ag₂CO₃ (165.6 mg, 0.6 mmol), KOAc (58.8 mg, 0.6 mmol), and DMAc (3 mL) were added to a thick-walled glass reaction flask. The flask was sealed and heated to 90 °C with magnetic stirring for 48 h. The reaction was then stopped, cooled to room temperature, and Soxhlet extraction was used to obtain ester-substituted polythiophene P8 (57.6 mg, 80% yield). 1 ¹H NMR (400MHz, CDCl₃) δ 8.15–7.58 (m, 1H), 4.30 (s, 1H), 1.74 (s, 2H), 1.24 (d, J = 17.6 Hz, 10H), 0.86 (s, 3H). Number-average molecular weight Mn was 24300, PDI 3.19 (GPC, THF).

[0098] The structure of monomer M in this embodiment is as follows:

[0099]

[0100] The preparation process of ester-substituted polythiophene from monomer M in this embodiment is as follows:

[0101]

[0102] Example 9

[0103] A method for preparing ester-substituted polythiophene, comprising:

[0104] Monomer M (72 mg, 0.3 mmol), palladium chloride (2.7 mg, 0.015 mmol), 1,3-bis(diphenylphosphine)propane (12.4 mg, 0.03 mmol), Ag₂CO₃ (165.6 mg, 0.6 mmol), KOAc (58.8 mg, 0.6 mmol), and DMAc (3 mL) were added to a thick-walled glass reaction flask. The flask was sealed and heated to 90 °C with magnetic stirring for 48 h. The reaction was then stopped, cooled to room temperature, and Soxhlet extraction was used to obtain ester-substituted polythiophene P9 (58.3 mg, 81% yield). 1 ¹H NMR (400MHz, CDCl₃) δ 8.15–7.55 (m, 1H), 4.30 (s, 1H), 1.74 (s, 2H), 1.24 (d, J = 13.9 Hz, 10H), 0.86 (s, 3H). Number-average molecular weight Mn was 44,100, PDI 2.62 (GPC, THF).

[0105] The structure of monomer M in this embodiment is as follows:

[0106]

[0107] The preparation process of ester-substituted polythiophene from monomer M in this embodiment is as follows:

[0108]

[0109] Example 10

[0110] Synthesis of 4'-phenyl-2,2':6',2'-terpyridine (L2) as a ligand

[0111]

[0112] Under ice-water bath conditions, benzaldehyde (1.06 g, 10 mmol) and 2-acetylpyridine (2.42 g, 20 mmol) were placed in a 250 mL three-necked round-bottom flask, and 50 mL of ethanol was added and stirred to dissolve. 10 mL of potassium hydroxide aqueous solution (containing 1.32 g (20 mmol) of potassium hydroxide) was added dropwise to the flask. The resulting mixture was reacted at 35 °C for 4 h. Then, 35 mL of ammonia (25-28%) was added to the reaction system, and the mixture was refluxed for another 7 h. The reaction was stopped, the mixture was filtered, and the filter cake was washed with cold ethanol (0 °C) and dried to obtain the crude product. Recrystallization of the crude product from ethanol yielded a yellow solid, L2 (1.66 g, yield 53.9%). 1 H NMR (400MHz, CDCl3) δ8.75 (d, J = 9.9 Hz, 4H), 8.69 (d, J = 8.0 Hz, 2H), 7.95-7.85 (m, 4H), 7.49 (dt, J = 9.1, 7.4Hz, 3H), 7.40-7.33 (m, 2H). (Gallelli Pratap, Tanneru Narasimhaswamy, Ponnusamy Shanmugam. Palladium(II)catalyzed arylation and methylene oxidation of 2,7-dibromo fluorenes with heteroaryl esters:synthesis of mesogenic2-heteroaryl and 2,7-diheteroaryl-9-fluorenones[J].ChemistrySelect, 2019,4:1795-1799.)

[0113] The structural formula of L2 is as follows:

[0114]

[0115] A method for preparing ester-substituted polythiophene, comprising:

[0116] Monomer M (72 mg, 0.3 mmol), palladium acetate (3.4 mg, 0.015 mmol), 4'-phenyl-2,2':6',2'-terpyridine (9.3 mg, 0.03 mmol) (L2), Ag2CO3 (165.6 mg, 0.6 mmol), KOAc (58.8 mg, 0.6 mmol), and DMAc (3 mL) were added to a thick-walled glass reaction flask. The flask was sealed and heated to 90 °C with magnetic stirring for 48 h. The reaction was then stopped, cooled to room temperature, and Soxhlet extraction was performed to obtain ester-substituted polythiophene P10 (51.2 mg, 71% yield). 1 ¹H NMR (400MHz, CDCl₃) δ 8.17–7.57 (m, ¹H), 4.30 (s, ¹H), 4.13 (s, ¹H), 1.75 (s, 2H), 1.24 (d, J = 19.9 Hz, ¹⁰H), 0.93–0.79 (m, ³H). Number-average molecular weight (Mn) was 13800, and PDI was 2.84 (GPC, THF).

[0117] The structure of monomer M in this embodiment is as follows:

[0118]

[0119] The preparation process of ester-substituted polythiophene from monomer M in this embodiment is as follows:

[0120]

[0121] Example 11

[0122] A method for preparing ester-substituted polythiophene, comprising:

[0123] Monomer M (72 mg, 0.3 mmol), Herrmann's catalyst (14.1 mg, 0.015 mmol), 1,3-bis(diphenylphosphine)propane (12.4 mg, 0.03 mmol), Ag₂CO₃ (165.6 mg, 0.6 mmol), KOAc (58.8 mg, 0.6 mmol), and DMAc (3 mL) were added to a thick-walled glass reaction flask. The flask was sealed and heated to 60 °C with magnetic stirring for 48 h. The reaction was then stopped, cooled to room temperature, and Soxhlet extraction was performed to obtain ester-substituted polythiophene P11 (64 mg, 89% yield). 1H NMR (400MHz, CDCl3) δ8.18-7.56(m,1H),4.39-4.06(m,2H),1.74(s,2H),1.37-1.16(m,10H),0.86(s,3H). Mn10400, PDI 1.39 (GPC, THF).

[0124] The structure of monomer M in this embodiment is as follows:

[0125]

[0126] The preparation process of ester-substituted polythiophene from monomer M in this embodiment is as follows:

[0127]

[0128] Examples 3, 5, and 7 show preparation methods at different reaction temperatures (all other reaction conditions are the same). Examples 3, 5, and 7 show that as the reaction temperature increases, the molecular weights of ester-substituted polythiophene are 10400, 80300, and 33800, respectively. The molecular weight of ester-substituted polythiophene first increases and then decreases, thereby achieving the control of the molecular weight of ester-substituted polythiophene.

[0129] Examples 1, 6, and 7 show the preparation methods under different amounts of ligand (all other reaction conditions are the same). Examples 1, 6, and 7 show that as the amount of ligand added increases, the molecular weights of ester-substituted polythiophene are 26400, 22900, and 22500, respectively. The molecular weight of ester-substituted polythiophene shows a decreasing trend, thereby achieving the control of the molecular weight of ester-substituted polythiophene.

[0130] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing ester-substituted polythiophene, characterized in that, include: Monomer M, palladium catalyst, ligand, oxidant, base, and solvent were mixed to obtain the reactant. The reactant was reacted at 80–110 °C for 48 hours, purified, and yielded ester-substituted polythiophene, wherein: The ligand is ; The monomer M is or ; The palladium catalyst is Pd(OAc)2, PdCl2, or Herrmann's catalyst; The oxidant is Ag2CO3; The alkali is KOAc; The ratio of monomer M, palladium catalyst, ligand, oxidant and base, by molar amounts, is 1:0.05:0.15:2:

2.

2. The preparation method according to claim 1, characterized in that, The solvent is one or a mixture of several of toluene, 1,4-dioxane, o-xylene, tetrahydrofuran, N,N-dimethylacetamide, N,N-diethylformamide, N,N-diethylacetamide, N,N-dimethylformamide and dimethyl sulfoxide.

3. The preparation method according to claim 1, characterized in that, The concentration of monomer M in the reactants is 0.1~0.5 mol / L.

4. The preparation method according to claim 1, characterized in that, The purification process is Soxhlet extraction.

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