A palladium catalyst and its application in the preparation of P3HT

Abstract

This invention discloses a palladium catalyst and its application in the preparation of P3HT. The structural formula of the palladium catalyst is shown in formula (I). The palladium catalyst provided by this invention can catalyze the polymerization at high temperature to prepare high molecular weight and high regularity P3HT, improve the yield of catalytic polymerization, and has broad application prospects in the fields of solar cells, organic transistors, electrochromic devices, chemical sensors, and electromagnetic shielding materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a palladium catalyst and its application in preparing P3HT. BACKGROUND

[0002] Poly 3-hexylthiophene belongs to polythiophene polymers, and has wide application prospects in the fields of solar cells, organic transistors, electrochromic devices, chemical sensors, electromagnetic shielding materials and the like due to its excellent electro-optical properties, environmental stability and solubility.

[0003] As a low-cost commercialized conjugated high-molecular hole transport material (HTM), poly 3-hexylthiophene (P3HT) has the advantage of easy preparation and does not require any dopant. In addition, its polymer property provides better film-forming property for solar cells, and is very suitable for large-area preparation methods. P3HT has been widely used as an HTM in perovskite solar cells, and in a polymer interlayer between a perovskite layer and an HTM. So far, the efficiency of perovskite solar cells using P3HT as an HTM or a polymer interlayer in their structure is as high as 23%.

[0004] High-molecular-weight and structurally regular P3HT has more excellent electrical and optical properties, and has a relatively high carrier mobility in a pure film or a blended film with PCBM. The Stille method can be used to synthesize P3HT with a higher regular structure, but the monomer preparation of the Stille method requires the use of an organic tin reagent, which is highly toxic and expensive, and the prepared polymer has a low molecular weight, resulting in low overall process efficiency. SUMMARY

[0005] The present application aims to overcome the defects and deficiencies of the prior art, and provides a palladium catalyst for catalyzing C-H activation and direct arylization polymerization to prepare a polymer. The raw material source is convenient, the stability is good, and the molecular weight and yield of the polymer can be simultaneously improved, thereby improving the production efficiency, reducing the production cost, and having practical production significance. At the same time, the palladium catalyst can be used to catalyze polymerization to prepare high-molecular-weight and high-regularity P3HT, and improve the yield of catalytic polymerization.

[0006] The present application aims to provide a palladium catalyst, and the structural formula of the palladium catalyst is shown as formula (I):

[0007]

[0008] wherein R is selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, cycloalkenyl, cycloalkynyl, naphthyl, acenaphthyl, camphor, benzhydryl, triphenylmethyl.

[0009] Preferably, the structural formula of the palladium catalyst is shown as formula (I):

[0010]

[0011] wherein R is selected from the group consisting of aryl, cycloalkyl, cycloalkenyl, cycloalkynyl, naphthyl, acenaphthyl, bornyl, benzhydryl, trityl,

[0012] More preferably, the palladium catalyst has a structural formula as shown in formula (I):

[0013]

[0014] wherein R is selected from the group consisting of benzhydryl, trityl,

[0015] More preferably, the palladium catalyst has a structural formula as shown in formula (I):

[0016]

[0017] wherein R is selected from the group consisting of xylyl.

[0018] Another object of the present application is to provide a preparation method of the palladium catalyst, comprising the following steps:

[0019] ligand reacting with (COD)PdCl2to obtain the palladium catalyst.

[0020] Preferably, the molar ratio of the ligand to (COD)PdCl2is 1.5-2.5:1.

[0021] More preferably, the molar ratio of the ligand to (COD)PdCl2is 2:1.

[0022] Preferably, the reaction temperature is 60-100°C and the reaction time is 0.3-0.8h.

[0023] More preferably, the reaction temperature is 80°C and the reaction time is 0.5h.

[0024] Preferably, the preparation method of the ligand comprises the following steps:

[0025] substituted aniline reacting with alcohol R-OH to obtain the ligand.

[0026] Preferably, the substituted aniline The molar ratio of the substituted aniline to alcohol R-OH is 0.45-3.3:1.

[0027] Preferably, the catalyst for the reaction comprises ZnCl2 / HCl.

[0028] Another object of the present application is to provide a polythiophene prepared by polymerization of a thiophene monomer catalyzed by the palladium catalyst.

[0029] Preferably, the molar ratio of the palladium catalyst to the thiophene monomer is 0.0015-0.0035:1.

[0030] More preferably, the molar ratio of the palladium catalyst to the thiophene monomer is 0.0025:1.

[0031] Preferably, the thiophene monomer comprises 2-bromo-3-hexylthiophene.

[0032] Preferably, an organic acid and an inorganic base are further added during the polymerization.

[0033] Preferably, the molar ratio of the organic acid to the thiophene monomer is 2-4:1.

[0034] More preferably, the molar ratio of the organic acid to the thiophene monomer is 3:1.

[0035] Preferably, the molar ratio of the inorganic base to the thiophene monomer is 1-2:1.

[0036] Preferably, the molar ratio of the inorganic base to the thiophene monomer is 1.4:1.

[0037] More preferably, the organic acid comprises pivalic acid.

[0038] More preferably, the inorganic base comprises anhydrous potassium carbonate.

[0039] Preferably, the reaction temperature of the polymerization is 80-120℃, and the reaction time of the polymerization is 12-36h.

[0040] More preferably, the reaction temperature of the polymerization is 100℃, and the reaction time of the polymerization is 24h.

[0041] Preferably, the reaction solvent of the polymerization comprises N,N-dimethylacetamide.

[0042] Compared with the prior art, the present application has the following beneficial effects:

[0043] The palladium catalyst provided by the present application can be used to prepare P3HT at high temperature, and the prepared P3HT has the advantages of high molecular weight, high regularity and high yield, has obvious economic benefits, and has wide application prospects in the fields of solar cells, organic transistors, electrochromic devices, chemical sensors, electromagnetic shielding materials, etc. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 NMR spectrum of the palladium catalyst C provided for Example 2.

[0045] Figure 2 NMR carbon spectrum of the palladium catalyst C provided in Example 2. DETAILED DESCRIPTION

[0046] The concept and the technical effects of the present application will be described clearly and completely in combination with the examples, so as to fully understand the purpose, features and effects of the present application. Obviously, the described examples are only some of the examples of the present application, but not all the examples. Based on the examples of the present application, other examples obtained by those skilled in the art without creative labor are within the protection scope of the present application. The test methods used in the examples are conventional methods, and the materials and reagents used in the examples are commercially available reagents and materials, unless otherwise specified.

[0047] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0048] (COD)PdCl2: (1,5-cyclooctadiene) palladium dichloride.

[0049] The palladium catalyst is prepared by the following reaction route:

[0050]

[0051] wherein R is benzhydryl.

[0052] In the following examples, the molecular weight and the molecular weight distribution of the prepared P3HT are determined by high temperature gel permeation chromatography (HT-GPC) (trichlorobenzene as solvent and mobile phase, concentration 1.5 g / L, flow rate 1 mL / min).

[0053] Example 1

[0054] The present example provides a ligand L, and the synthesis method thereof is as follows:

[0055] Under a nitrogen atmosphere, compound A (5 mmol) and benzyl alcohol (10 mmol) were added sequentially to a side-necked flask. The mixture was stirred at 80 °C and refluxed for 60 min (molten state). Then, a ZnCl2 / concentrated HCl solution (ZnCl2 (0.75 g) and concentrated HCl (1 ml)) was added using a syringe. The mixture was reacted at 140 °C for 6 h. After the reaction was completed, the mixture was cooled to room temperature, dissolved in an appropriate amount of dichloromethane, and transferred to a beaker. A saturated sodium bicarbonate solution was added to adjust the pH of the solution to 7. The mixture was stirred for 30 min, and the zinc salt was removed by filtration. The filtrate was separated, and the organic layer was collected. Anhydrous sodium sulfate was added to remove water, and the mixture was filtered, evaporated to dryness, passed through a silica gel column, evaporated to dryness, recrystallized (with anhydrous ethanol), filtered, and dried to obtain a white compound L with a yield of 57%.

[0056] Example 2

[0057] This embodiment provides a catalyst C, the synthesis method of which is as follows:

[0058] The ligand L (1 mmol) and (COD)PdCl2 (0.5 mmol) prepared in the example were dissolved in DMAC (1.5 ml), and the mixture was stirred at 80 °C for 0.5 h. After the reaction was cooled, methanol was added to precipitate the solid. The solid was filtered, dissolved, and passed through a silica gel column. The solid was then evaporated to dryness, recrystallized (in anhydrous ethanol), filtered and dried to give yellow compound C with a yield of 79%.

[0059] 1 H NMR(400MHz, CDCl3)δ8.54(s,2H),7.91(d,J=8.9Hz,2H),7.12(td,J=7.7,2.1Hz,46H),7.00-6.94 (m,8H),6.89(dd,J=7.3,2.3Hz,8H),6.35(d,J=9.7Hz,4H),6.02(s,2H),5.70(s,2H),4.66(s,4H).

[0060] 13 C NMR (101MHz, CDCl3) δ147.70,141.63,135.58,133.50,129.75,129.51,128.54,127.00,126.02,51.80,34.44,30.91.

[0061] Comparative Example 1

[0062] This comparative example provides a palladium catalyst C1, the synthesis method of which is as follows.

[0063]

[0064] Acetylacetone (10 mmol) and 2,6-diisopropylaniline A1 (22 mmol) were placed in a round-bottom flask, and 40 mL of anhydrous ethanol was added. 1.5 mL of concentrated hydrochloric acid was slowly added dropwise under vigorous stirring. The mixture was heated under reflux for 3 days. After filtration, a white solid was obtained, which was redissolved in dichloromethane. The solution was adjusted to neutral with saturated NaHCO3. After extraction and separation, the solvent was removed by vacuum distillation to obtain a pale yellow solid β-diimine L1, with a yield of 61%.

[0065] Weigh 1 mmol of β-diimine L1 and 1 mmol of (COD)PdCl2 into a side-necked flask, add 18 mL of methanol, and reflux for 16 h under N2 protection. After the reaction is complete, filter out the yellow solid, elute rapidly with a short silica gel column, and recrystallize from dichloromethane / n-hexane to give yellow solid C1, with a yield of 47%.

[0066] The palladium catalyst C from Example 2 and the palladium catalyst C1 prepared in Comparative Example 1 were used to catalyze the polymerization of 2-bromo-3-hexylthiophene to obtain P3HT. The specific steps are as follows:

[0067]

[0068] Take clean, anhydrous, and oxygen-free parallel reaction apparatus flasks, and place magnetic stir bar in each flask. Add 0.5 mmol of 2-bromo-3-hexylthiophene, 0.7 mmol of anhydrous potassium carbonate, 0.15 mmol of neopentanoic acid, and 4 ml of N,N-dimethylacetamide as solvent to each of the six flasks. Then add 0.25% palladium catalyst C to C2 to each flask. Heat to 100°C under natural conditions, and stir for 24 hours. Stop heating, add 20 ml of methanol to precipitate a reddish-brown solid product, filter, dry, wrap the product in filter paper, place it in a Soxhlet extractor, and extract with n-hexane as solvent until the siphoned solvent is colorless. Dry the product, weigh it, and characterize the polymer by GPC. The catalytic polymerization results are shown in Table 1.

[0069] Table 1. Results of 2-bromo-3-hexylthiophene polymerization catalyzed by different palladium catalysts.

[0070] Examples Palladium catalyst Yield (%) M n (g / mol) PDI HT (%) Example 2 C 75 26273 2.10 93 Comparative Example 1 C1 57 7423 1.45 80

[0071] As shown in Table 1, the P3HT prepared in Example 2 of this invention has a high molecular weight and regularity, and a high yield.

[0072] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A palladium catalyst characterized in that, The structural formula of the palladium catalyst is shown as formula (I): Formula (I) wherein R is selected from the group consisting of benzhydryl, triphenylmethyl, .

2. The palladium catalyst according to claim 1, characterized in that The structural formula of the palladium catalyst is shown as formula (I): Formula (I) Wherein, R is selected from benzhydryl.

3. Process for the preparation of a palladium catalyst according to any one of claims 1 to 2, characterized in that, The method comprises the following steps: ligand The palladium catalyst is obtained by reaction with (COD)PdCl2.

4. The method of claim 3, wherein the palladium catalyst is prepared by, The method for preparing the ligand comprises the following steps: with an alcohol to give the ligand.

5. The use of the palladium catalyst prepared by the method for preparing the palladium catalyst according to any one of claims 1-4 in catalyzing the polymerization of thiophene monomers.

6. Use according to claim 5, characterized in that, The thiophene monomers comprise 2-bromo-3-hexylthiophene.

7. Use according to claim 5, characterized in that, An organic acid and an inorganic base are also added in the polymerization process.

8. Use according to claim 5, characterized in that, The reaction temperature of the polymerization is 80-120 DEG C, and the reaction time of the polymerization is 12-36 h.

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