An asymmetric α-diimine palladium catalyst, its preparation method and application

Abstract

This invention discloses an asymmetric α-diimine palladium catalyst, its preparation method, and its applications. The structural formula of the asymmetric α-diimine palladium catalyst is shown in formula (I) or formula (II). The asymmetric α-diimine palladium catalyst provided by this invention can catalyze the polymerization at high temperatures to prepare P3HT with high yield, high molecular weight, and high regularity. It 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 catalyst, in particular to an asymmetric α-diimine palladium catalyst and a preparation method and application thereof. BACKGROUND

[0002] Poly 3-hexylthiophene belongs to polythiophene polymer, 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 polymer hole transport material (HTM), poly 3-hexylthiophene (P3HT) has the advantage of being easy to prepare, and does not need 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 the perovskite layer and the HTM. So far, the efficiency of the perovskite solar cell using P3HT as an HTM or a polymer interlayer in its structure is as high as 23%.

[0004] However, P3HT with high molecular weight and regular structure has more excellent electrical and optical properties, and has a relatively high carrier mobility in a pure film or a blended film with PCBM. Regular structure P3HT can be synthesized by Rieke method, but it is difficult to prepare high-activity “Rieke zinc” by Rieke method, and the equipment requirement is high, the catalytic yield is low, and it is difficult to obtain P3HT with high molecular weight. SUMMARY

[0005] The present application aims to overcome the defects and deficiencies of the prior art, and provides an asymmetric α-diimine palladium catalyst, which can catalyze polymerization at high temperature to prepare P3HT with high yield, high molecular weight and high regularity.

[0006] The present application aims to provide an asymmetric α-diimine palladium catalyst, and the structural formula of the asymmetric α-diimine palladium catalyst is shown in formula (I) or formula (II):

[0007]

[0008] wherein R, R1 are independently selected from alkyl, alkenyl, alkynyl, aryl, cycloalkyl, cycloalkenyl, cycloalkynyl, naphthyl, acenaphthyl, camphor, benzhydryl, triphenylmethyl, R2 is selected from hydrogen or R2 is the same as R1, and R and R2 are not the same, and when R is isopropyl, R2 is not benzhydryl.

[0009] More preferably, the structural formula of the asymmetric α-diimine palladium catalyst is shown in formula (I) or formula (II):

[0010]

[0011] wherein, R, R1 are independently selected from alkyl, benzhydryl, trityl, R2 is selected from hydrogen or R2 is the same as R1, and R is not the same as R2, when R is isopropyl, R2 is not benzhydryl.

[0012] More preferably, the asymmetric α-diimine palladium catalyst has a structural formula as shown in formula (I) or formula (II):

[0013]

[0014] wherein, when R is selected from methyl, ethyl, propyl or tert-butyl, R1, R2 are both selected from xylyl;

[0015] when R is selected from isopropyl, R1 is selected from trityl or benzhydryl, and R2 is selected from hydrogen.

[0016] More preferably, the asymmetric α-diimine palladium catalyst has a structural formula as shown in formula (I) or formula (II):

[0017]

[0018] wherein, when R is selected from methyl or ethyl, R1, R2 are both selected from xylyl;

[0019] when R is selected from isopropyl, R1 is selected from trityl, and R2 is selected from hydrogen.

[0020] Another object of the present application is to provide a preparation method of the asymmetric α-diimine palladium catalyst, comprising the following steps:

[0021] a ligand reacting with palladium chloride to obtain the asymmetric α-diimine palladium catalyst.

[0022] Preferably, the molar ratio of the ligand to palladium chloride is 1.05-1.2:1.

[0023] More preferably, the molar ratio of the ligand to palladium chloride is 1.1:1.

[0024] Preferably, the reaction temperature is 40-80°C, and the reaction time is 12-18h.

[0025] More preferably, the reaction temperature is 60°C, and the reaction time is 16h.

[0026] Preferably, the preparation method of the ligand comprises the following steps:

[0027] S1. aniline reacting with an alcohol R1-OH to obtain a substituted aniline

[0028] S2. said substituted aniline with a diketone to obtain said ligand.

[0029] Preferably, said aniline is reacted with an alcohol R1-OH in a molar ratio of 1:1.1-1.3.

[0030] Preferably, in S1, the catalyst for said reaction comprises ZnCl2 / HCl.

[0031] Preferably, in S2, said substituted aniline is reacted with a diketone in a molar ratio of 2.1-2.5:1.

[0032] Preferably, in S2, said substituted aniline is reacted with a diketone in a molar ratio of 2.1-2.5:1.

[0033] Preferably, in S2, said reaction is carried out at a temperature of 20-140°C for a time of 5-24h.

[0034] Another object of the present application is to provide a polythiophene obtained by polymerization of a thiophene monomer catalyzed by said asymmetric α-diimine palladium catalyst.

[0035] Preferably, said asymmetric α-diimine palladium catalyst is used in a molar ratio of 0.0015-0.0035:1 with respect to the thiophene monomer.

[0036] More preferably, said asymmetric α-diimine palladium catalyst is used in a molar ratio of 0.0025:1 with respect to the thiophene monomer.

[0037] Preferably, said thiophene monomer comprises 2-bromo-3-hexylthiophene.

[0038] Preferably, an organic acid and an inorganic base are also added during the polymerization.

[0039] Preferably, said organic acid is used in a molar ratio of 2-4:1 with respect to the thiophene monomer.

[0040] More preferably, said organic acid is used in a molar ratio of 3:1 with respect to the thiophene monomer.

[0041] Preferably, said inorganic base is used in a molar ratio of 1-2:1 with respect to the thiophene monomer.

[0042] Preferably, said inorganic base is used in a molar ratio of 1.4:1 with respect to the thiophene monomer.

[0043] More preferably, said organic acid comprises pivalic acid.

[0044] More preferably, the inorganic base includes anhydrous potassium carbonate.

[0045] Preferably, the polymerization reaction temperature is 80–120°C, and the polymerization reaction time is 12–36 h.

[0046] More preferably, the polymerization reaction temperature is 100°C and the polymerization reaction time is 24 hours.

[0047] Preferably, the reaction solvent for the polymerization includes N,N-dimethylacetamide.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The asymmetric α-diimine palladium catalyst provided by this invention can prepare P3HT at high temperature. The prepared P3HT has the advantages of high molecular weight, high yield and high regularity, and has significant economic benefits. It has broad application prospects in the fields of solar cells, organic transistors, electrochromic devices, chemical sensors, and electromagnetic shielding materials. Attached Figure Description

[0050] Figure 1 The 1H NMR spectrum of the asymmetric α-diimine palladium catalyst C1 provided in Example 4.

[0051] Figure 2 The image shows the carbon NMR spectrum of the asymmetric α-diimine palladium catalyst C1 provided in Example 4.

[0052] Figure 3 The 1H NMR spectrum of the asymmetric α-diimine palladium catalyst C2 provided in Example 5.

[0053] Figure 4 The image shows the carbon NMR spectrum of the asymmetric α-diimine palladium catalyst C2 provided in Example 5.

[0054] Figure 5 The 1H NMR spectrum of the asymmetric α-diimine palladium catalyst C3 provided in Example 6.

[0055] Figure 6 The carbon NMR spectrum of the asymmetric α-diimine palladium catalyst C3 provided in Example 6. Detailed Implementation

[0056] The following will describe the concept and technical effects of the present invention clearly and completely with reference to the embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0057] The asymmetric α-diimine palladium catalyst was prepared via the following reaction route:

[0058]

[0059] In the following examples, the molecular weight and molecular weight distribution of the prepared P3HT were determined by high-temperature gel permeation chromatography (HT-GPC) using trichlorobenzene as solvent and mobile phase, concentration 1.5 g / L, flow rate 1 mL / min.

[0060] Example 1

[0061] This embodiment provides a ligand L1, the synthesis method of which is as follows:

[0062] Under a nitrogen atmosphere, 2-methylaniline (5 mmol) and diphenylmethanol (5.5 mmol) were added sequentially to a bottle with a side arm. The mixture was stirred at 80 °C and refluxed for 30 min (in molten state). Then, freshly prepared ZnCl2 / concentrated HCl (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. 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 the white compound 2-methyl-4-diphenylmethyl-6-diphenylmethylaniline, with a yield of 80%.

[0063] 2-Methyl-4-diphenylmethyl-6-diphenylmethylaniline (2.2 mmol), glyoxal (1 mmol), and ethanol (4 ml) were added sequentially to a side-necked flask. 0.1 mL of glacial acetic acid was added as a catalyst. The mixture was stirred at room temperature for 24 h. After the reaction was completed, the mixture was filtered and dried to obtain a yellow solid ligand L1 with a yield of 68%.

[0064] Example 2

[0065] This embodiment provides a ligand L2, the synthesis method of which is as follows:

[0066] Under a nitrogen atmosphere, 2-isopropylaniline (5 mmol) and triphenylmethanol (5.5 mmol) were added sequentially to a bottle with a side arm. The mixture was stirred at 80 °C and refluxed for 30 min (in molten state). Then, freshly prepared ZnCl2 / concentrated HCl (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. 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 the white compound 2-isopropyl-4-triphenylmethylaniline, with a yield of 76%.

[0067] Under a nitrogen atmosphere, 2-isopropyl-4-triphenylmethylaniline (2.2 mmol), acenaphthoquinone (1 mmol), and anhydrous ZnCl (0.3 g) were added sequentially to a side-necked flask. 5 mL of glacial acetic acid was added as a solvent, and the mixture was slowly heated to 140 °C and refluxed for 5 h. After the reaction was cooled to room temperature, the mixture was filtered (the solid was washed with n-hexane), dried, and the resulting zinc complex was dissolved in dichloromethane in a beaker. Potassium oxalate aqueous solution was added to the beaker and stirred for 12 h to remove zinc. The organic layer was separated by standing, and anhydrous sodium sulfate was added to remove water. The mixture was filtered, evaporated to dryness, and recrystallized with anhydrous ethanol to give a yellow solid ligand L2 with a yield of 62%.

[0068] Example 3

[0069] This embodiment provides a ligand L3, the synthesis method of which is as follows:

[0070] Under a nitrogen atmosphere, 2-ethylaniline (5 mmol) and diphenylmethanol (5.5 mmol) were added sequentially to a bottle with a side arm. The mixture was stirred at 80 °C and refluxed for 30 min (in molten state). Then, freshly prepared ZnCl2 / concentrated HCl (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. 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 the white compound 2-ethyl-4,6-diphenylmethylaniline, with a yield of 84%.

[0071] Under a nitrogen atmosphere, 2-ethyl-4,6-diphenylmethylaniline (2.2 mmol), acenaphthoquinone (1 mmol), and anhydrous ZnCl (0.3 g) were added sequentially to a side-necked flask. 5 mL of glacial acetic acid was added as a solvent, and the mixture was slowly heated to 140 °C and refluxed for 5 h. After cooling to room temperature, the mixture was filtered (the solid was washed with n-hexane), dried, and the resulting zinc complex was dissolved in dichloromethane in a beaker. Potassium oxalate aqueous solution was added to the beaker and stirred for 12 h to remove zinc. The organic layer was separated by standing, and anhydrous sodium sulfate was added to remove water. The mixture was filtered, evaporated to dryness, and recrystallized with anhydrous ethanol to give a yellow solid ligand L3 with a yield of 79%.

[0072] Example 4

[0073] This embodiment provides an asymmetric α-diimine palladium catalyst C1, the synthesis method of which is as follows:

[0074] Under a nitrogen atmosphere, ligand L1 (0.5 mmol), (COD)PdCl2 (0.55 mmol), and methanol (8 ml) were added to a side-necked flask. The mixture was refluxed at 60 °C for 16 h. After the reaction was completed, the mixture was cooled to room temperature and eluted by dry column chromatography using dichloromethane as the eluent. The filtrate was collected, evaporated to dryness, dissolved in a small amount of dichloromethane, and slowly added dropwise to an anhydrous ethanol solution under stirring. A solid precipitated out. The solid was washed several times, filtered, and dried to obtain solid compound C1 with a yield of 84%.

[0075] 1 H NMR (400MHz, CDCl3) δ7.21(ddd,J=16.5,7.5,5.1Hz,21H),7.15-7.08(m,13H),7.03-6.98(m,9H),6.89(d,J=1.8Hz,1H),6.85(d,J=1.8Hz,1 H),6.66(d,J=1.8Hz,1H),6.56(d,J=1.8Hz,1H),6.19(s,1H),5.99(s,1H),5.41(s,2H),2.35(s,3H),2.16(s,3H),1.04(s,3H),0.64(s,3H).

[0076] 13C NMR (101MHz, CDCl3) δ143.60,143.57,143.50,143.40,143.37,142.50,141.6 5,141.63,141.23,140.85,136.64,136.09,130.40,129.97,129.72,129.64,1 29.47,129.37,129.35,129.30,128.88,128.72,128.27,128.25,127.96,127.92,126.76,126.30,56.15,56.13,52.62,52.06,19.21,18.69,18.66,18.57.

[0077] Example 5

[0078] This embodiment provides an asymmetric α-diimine palladium catalyst C2, the synthesis method of which is as follows:

[0079] Under a nitrogen atmosphere, ligand L2 (0.5 mmol), (COD)PdCl2 (0.55 mmol), and methanol (8 ml) were added to a side-necked flask. The mixture was refluxed at 60 °C for 16 h. After the reaction was completed, the mixture was cooled to room temperature and eluted by dry column chromatography using dichloromethane as the eluent. The filtrate was collected, evaporated to dryness, dissolved in a small amount of dichloromethane, and slowly added dropwise to an anhydrous ethanol solution under stirring. A solid precipitated, was washed several times, filtered, and dried to give a yellow solid compound C2 with a yield of 86%.

[0080] 1 H NMR (400MHz, CDCl3) δ8.02(d,J=8.3Hz,2H),7.40(s,2H),7.28(dt,J=15.1,7.9Hz,26H),7.22-7.14(m,8H),7.03(dd,J=8 .4,2.4Hz,2H),6.18(dd,J=7.2,3.1Hz,2H),3.53(dt,J=25.5,6.8Hz,2H),1.34-1.25(m,6H),0.69(dd,J=9.4,7.1Hz,6H).

[0081] 13C NMR (101MHz, CDCl3) δ175.19,175.16,148.40,148.38,146.47,146.44,14 0.90,140.78,140.51,140.33,132.22,132.17,131.23,130.96,130.94,1 29.77,129.74,129.64,129.61,128.86,127.70,126.06,125.97,125.95, 124.64,120.95,120.83,65.37,29.46,29.30,24.30,23.97,22.96,22.74.

[0082] Example 6

[0083] This embodiment provides an asymmetric α-diimine palladium catalyst C3, the synthesis method of which is as follows:

[0084] Under a nitrogen atmosphere, ligand L3 (0.5 mmol), (COD)PdCl2 (0.55 mmol), and methanol (8 ml) were added to a side-necked flask. The mixture was refluxed at 60 °C for 16 h. After the reaction was completed, the mixture was cooled to room temperature and eluted by dry column chromatography using dichloromethane as the eluent. The filtrate was collected, evaporated to dryness, dissolved in a small amount of dichloromethane, and slowly added dropwise to an anhydrous ethanol solution under stirring. A solid precipitated, was washed several times, filtered, and dried to give a yellow solid compound C3 with a yield of 81%.

[0085] 1 H NMR(400MHz, CDCl3)δ7.81(d,J=8.3Hz,2H),7.34-7.28(m,6H),7.24(d,J=3.3Hz,2H), 7.21(s,1H),7.19(d,J=3.3Hz,1H),7.17-7.05(m,23H),7.00-6.96(m,4H),6.68(d,J=1 .9Hz,2H),6.58(s,2H),6.32(t,J=7.5Hz,4H),6.11-6.00(m,4H),5.53(s,2H),5.29(s, 1H), 3.10 (dq, J=15.1, 7.5Hz, 2H), 2.56 (dq, J=15.1, 7.5Hz, 2H), 1.42 (t, J=7.5Hz, 6H).

[0086] 13C NMR (101MHz, CDCl3) δ176.92,144.13,143.50,143.36,142.05,140.62,140.43,137.48,134.98,131.37,129.85,129.74,129.53,129 .38,129.25,128.33,128.26,127.87,127.75,127.61,127.40,126.41,126.36,126.29,125.28,123.78,56.40,52.73,24.25,13.63.

[0087] Comparative Example 1

[0088] This comparative example provides a palladium catalyst C4, the synthesis method of which is as follows.

[0089]

[0090] Acetylacetone (10 mmol) and 2,6-diisopropylaniline A4 (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 L4, with a yield of 61%.

[0091] 1 mmol of β-diimine L4 and 1 mmol of (COD)PdCl2 were weighed into a side-necked flask, and 18 mL of methanol was added. The reaction was refluxed for 16 h under N2 protection. After the reaction was completed, the yellow solid was filtered off, rapidly eluted with a short silica gel column, and recrystallized from dichloromethane / n-hexane to give yellow solid C4 in 47% yield.

[0092] P3HT was obtained by catalyzing the polymerization of 2-bromo-3-hexylthiophene with the asymmetric α-diimine palladium catalysts C1-C3 from Examples 4-6 and the asymmetric α-diimine palladium catalyst C4 prepared in Comparative Example 1, respectively. The specific steps are as follows:

[0093]

[0094] A clean, anhydrous, and oxygen-free parallel reaction apparatus was used. Magnetic stirrers were placed in each of the six reaction flasks. 2-bromo-3-hexylthiophene (0.5 mmol), anhydrous potassium carbonate (0.7 mmol), neopentanoic acid (0.15 mmol), and 4 ml of N,N-dimethylacetamide were added as solvents. Then, 0.25% of the asymmetric α-diimide palladium catalyst (C1-C4) was added to each flask. The mixture was heated to 100 °C under natural conditions and stirred for 24 hours. Heating was then stopped, and 20 ml of methanol was added to precipitate a reddish-brown solid product. This solid was filtered, dried, wrapped in filter paper, and placed in a Soxhlet extractor. Hexane was added as solvent for extraction until the siphoned solvent was colorless. The product was dried, weighed, and the polymer was characterized by GPC. The catalytic polymerization results are shown in Table 1.

[0095] Table 1. Results of 2-bromo-3-hexylthiophene polymerization catalyzed by different asymmetric α-diimine palladium catalysts.

[0096] Examples Asymmetric a-diimine palladium catalyst Yield (%) M n (g / mol)]]> PDI HT (%) Example 4 C1 82 15697 2.15 94 Example 5 C2 79 15234 2.34 95 Example 6 C3 80 15023 2.38 92 Comparative Example 1 C4 57 7423 1.45 80

[0097] As shown in Table 1, the P3HT prepared in Examples 4 to 6 of this invention has high molecular weight and regularity, and a narrow molecular weight distribution.

[0098] 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. An asymmetric a-diimine palladium catalyst characterized in that, The asymmetric α-diimine palladium catalyst has a structural formula as shown in formula (I) or formula (II): wherein R is selected from ethyl, propyl or tert-butyl, R1 and R2 are both selected from benzhydryl; or R is selected from isopropyl, R1 is selected from triphenylmethyl or benzhydryl, and R2 is selected from hydrogen.

2. The asymmetric a-diimine palladium catalyst of claim 1, wherein, The asymmetric α-diimine palladium catalyst has a structural formula as shown in formula (I) or formula (II): wherein R is selected from ethyl, R1 and R2 are both selected from benzhydryl; or R is selected from isopropyl, R1 is selected from triphenylmethyl, and R2 is selected from hydrogen.

3. Process for the preparation of the asymmetric α-diimine palladium catalyst according to any one of claims 1 to 2, characterized in that, The method comprises the following steps: ligand with palladium chloride to give the asymmetric α-diimine palladium catalyst.

4. The process for the preparation of an asymmetric a-diimine palladium catalyst according to claim 3, characterized in that, The method for preparing the ligand comprises the following steps: S1. with an alcohol to give substituted aniline ; S2. said substituted aniline with a diketone to give said ligand.

5. Application of the asymmetric α-diimine palladium catalyst prepared by the method for preparing the asymmetric α-diimine palladium catalyst according to any one of claims 1-2 or 3-4 in catalyzing polymerization of a thiophene monomer.

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

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

8. Use according to claim 5, characterized in that, The polymerization is carried out at a temperature of 80-120 ℃ for 12-36 h. The polymerization is carried out at a temperature of 80-120 ℃ for 12-36 h.

Images