Dihexylfluorene-long chain alkyl aniline polymers and methods for their preparation

Abstract

The application discloses a dihexylfluorene-long-chain alkyl aniline polymer and a preparation method thereof, and belongs to the technical field of organic polymer polymers. The structural formula of the polymer is shown as formula (I): formula (I). The introduction of the long-chain alkyl aniline in the polymer does not destroy the conjugated structure of the polymer chain, and can appropriately increase the distance between dihexylfluorene units, inhibit the association phenomenon, and then be beneficial to obtaining obvious narrow-peak, single-peak fluorescence emission spectrum and pure light-emitting color.

Description

Technical Field

[0001] This invention belongs to the field of organic polymers, and particularly relates to a dihexylfluorene-long-chain alkylaniline polymer and its preparation method. Background Technology

[0002] Poly(dihexylfluorene), as a material with significant fluorescence properties, has shown broad application potential in organic light-emitting devices, bioimaging, and phototransfer films. However, the relatively short hexyl side chains of poly(dihexylfluorene) result in strong interactions between the chains, making them prone to association. This leads to a redshift in the fluorescence emission spectrum and the presence of obvious broad peaks and multi-peak defects. Consequently, the emitted color also exhibits an impure blue-green hue, limiting its application in pure color emission fields.

[0003] Therefore, providing a polydihexylfluorene-based fluorescent material with pure emission color is an urgent problem to be solved in this field. Summary of the Invention

[0004] To address the shortcomings of the existing technology, a dihexylfluorene-long-chain alkylaniline polymer and its preparation method are provided. The dihexylfluorene-long-chain alkylaniline polymer contains dihexylfluorene units and long-chain alkylaniline units in its structure. On the one hand, long-chain alkylaniline is not a bulky, twisted, non-coplanar monomer, and its introduction will not destroy the conjugated structure of the polymer chain. On the other hand, the introduction of long-chain alkylaniline can appropriately increase the distance between dihexylfluorene units and suppress association, thereby facilitating the acquisition of obvious narrow-peak, single-peak fluorescence emission spectra and corresponding pure emission colors.

[0005] The purpose of this invention is to provide a dihexylfluorene-long-chain alkylaniline polymer, the structural formula of which is shown in formula (I):

[0006] Equation (Ⅰ);

[0007] Wherein, R is an alkyl group with 5 to 12 carbon atoms, a number average molecular weight of 50 kDa to 150 kDa, and a PDI of 1.5 to 3.5.

[0008] In some embodiments of the present invention, R is pentyl, hexyl, octyl or dodecyl.

[0009] In some embodiments of the present invention, the structural formula of the dihexylfluorene-long-chain alkylaniline polymer is shown in formula (II):

[0010] Equation (II);

[0011] Among them, the number average molecular weight is 50kDa~150kDa, and the PDI is 1.5-3.5.

[0012] In some embodiments of the present invention, the structural formula of the dihexylfluorene-long-chain alkylaniline polymer is shown in formula (Ⅲ):

[0013] Formula (Ⅲ);

[0014] Among them, the number average molecular weight is 80kDa~95kDa, and the PDI is 2.0~2.5.

[0015] In some embodiments of the present invention, the structural formula of the dihexylfluorene-long-chain alkylaniline polymer is shown in formula (Ⅳ):

[0016] Formula (Ⅳ);

[0017] Among them, the number average molecular weight is 70kDa~85kDa, and the PDI is 2.5~3.0.

[0018] In some embodiments of the present invention, the structural formula of the dihexylfluorene-long-chain alkylaniline polymer is shown in formula (V):

[0019] Formula (V);

[0020] Among them, the number average molecular weight is 65kDa~75kDa, and the PDI is 2.2~2.8.

[0021] In some embodiments of the present invention, the raw materials for preparing the dihexylfluorene-long-chain alkylaniline polymer include: long-chain alkyl-substituted aniline. and 2,7-dibromo-9,9-di-n-hexylfluorene .

[0022] Another object of the present invention is to provide a method for preparing the dihexylfluorene-long-chain alkylaniline polymer, comprising the following steps:

[0023] Long-chain alkyl-substituted aniline is produced under the action of palladium catalyst and auxiliaries. and 2,7-dibromo-9,9-di-n-hexylfluorene The reaction yields the dihexylfluorene-long-chain alkylaniline polymer.

[0024] In some embodiments of the present invention, the molar ratio of the long-chain alkyl-substituted aniline to the 2,7-dibromo-9,9-di-n-hexylfluorene is 1:1 to 1.1.

[0025] In some embodiments of the present invention, the molar ratio of the palladium catalyst to the 2,7-dibromo-9,9-di-n-hexylfluorene is 0.005 to 0.02:1.

[0026] In some embodiments of the present invention, the structure of the palladium catalyst is shown in formula (VI):

[0027] Formula (VI);

[0028] Among them, R 1 R 2 It can be hydrogen, methyl, ethyl, or isopropyl independently, and R 1 R 2 They are not both hydrogen.

[0029] In some embodiments of the present invention, the auxiliary agent includes an organic base and a solvent.

[0030] In some embodiments of the present invention, the organic base is potassium tert-butoxide.

[0031] In some embodiments of the present invention, the molar ratio of the organic base to the 2,7-dibromo-9,9-di-n-hexylfluorene is 2 to 4:1.

[0032] In some embodiments of the present invention, the solvent is toluene.

[0033] In some embodiments of the present invention, the ratio of the solvent to the 2,7-dibromo-9,9-di-n-hexylfluorene is 2L~4L:1mol.

[0034] In some embodiments of the present invention, the reaction temperature is 100~120°C and the time is 12~36 hours.

[0035] In some embodiments of the present invention, the reaction is carried out in an inert gas atmosphere.

[0036] In some embodiments of the present invention, a post-processing step is further included after the reaction is completed.

[0037] In some embodiments of the present invention, the post-processing step includes a step of precipitation with methanol.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) In the structure of the dihexylfluorene-long-chain alkylaniline polymer, the long-chain alkylaniline unit can appropriately increase the distance between the dihexylfluorene units and suppress the association phenomenon without destroying the conjugated structure of the polymer chain, thereby obtaining obvious narrow peak, single-peak fluorescence emission spectrum and pure emission color;

[0040] (2) When the long chain in long-chain alkylaniline is a relatively long C8 alkyl chain or C12 alkyl chain, even under high temperature conditions, the fluorescence emission spectrum of dihexylfluorene-long-chain alkylaniline polymer still shows obvious narrow peaks and single peaks, and the emission wavelength remains almost unchanged, that is, the emission color is pure and stable. Attached Figure Description

[0041] Figure 1 The dihexylfluorene-long-chain alkylaniline polymer prepared in Example 4 of this invention 1 H NMR spectrum;

[0042] Figure 2 The UV absorption spectrum and fluorescence emission spectrum of the dihexylfluorene-long-chain alkylaniline polymer prepared in Example 4 of this invention are shown. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0044] All raw materials used in this invention are commercially available.

[0045] The structure of imidazole salt ligand L1 is shown below:

[0046] ;

[0047] The structure of imidazole salt ligand L2 is shown below:

[0048] ;

[0049] The structure of imidazole salt ligand L3 is shown below:

[0050] .

[0051] Example 1

[0052] This embodiment provides a palladium catalyst C1, the preparation method of which includes the following steps:

[0053] Imidazole salt ligand L1 (1.0 mmol), potassium carbonate (10 mmol), and palladium dichloride (1.0 mmol) were added to 10 mL of N-methylimidazole and mixed at room temperature. The mixture was then heated to 80°C and stirred for 12 hours. After the reaction was completed, the liquid was removed under reduced pressure, and the crude product was dissolved in 5 mL of dichloromethane. Subsequently, 20 mL of n-hexane was added, and the resulting palladium complex precipitate was collected by filtration, washed with n-hexane (2 × 20 mL), and dried to obtain a grayish-white palladium catalyst powder C1 with a yield of 81%. The NMR C-H spectrum of palladium catalyst C1 is as follows:

[0054] 1 H NMR (400 MHz, CDCl3) δ 7.50 (td, J = 1.6, 0.8 Hz, 1H), 7.12-7.07(m, 5H), 7.00 (dd, J = 5.6, 1.7 Hz, 1H), 6.85-6.81 (m, 4H), 6.60 (s, 4H), 3.82 (s, 6H), 3.72 (d, J = 0.6 Hz, 3H), 2.31 (s, 12H), 2.26 (d, J = 0.7 Hz, 6H).

[0055] 13 C NMR (101 MHz, CDCl3) δ 162.02, 156.48, 133.58, 133.45, 133.24,130.79, 130.15, 129.44, 127.53, 122.13, 116.03, 103.07, 62.77, 55.35, 35.03,21.03, 18.14.

[0056] The structure of palladium catalyst C1 is shown below:

[0057] .

[0058] Example 2

[0059] This embodiment provides a palladium catalyst C2, the preparation method of which includes the following steps:

[0060] Imidazole salt ligand L2 (1.0 mmol), potassium carbonate (8 mmol), and palladium dichloride (1.0 mmol) were added to 8 mL of N-methylimidazole and mixed at room temperature. The mixture was then heated to 70°C and stirred for 16 hours. After the reaction was completed, the liquid was removed under reduced pressure, and the crude product was dissolved in 5 mL of dichloromethane. Subsequently, 20 mL of n-hexane was added, and the resulting palladium complex precipitate was collected by filtration, washed with n-hexane (2 × 20 mL), and dried to obtain a grayish-white palladium catalyst powder C2 with a yield of 76%. The NMR C-H spectrum of palladium catalyst C2 is as follows:

[0061] 1 H NMR (400 MHz, CDCl3) δ 7.50 (tt, J = 1.4, 0.7 Hz, 1H), 7.13-7.08(m, 5H), 7.00 (dd, J = 5.6, 1.7 Hz, 1H), 6.87-6.80 (m, 8H), 6.79-6.73 (m,2H), 3.82 (s, 6H), 3.72 (t, J = 0.7 Hz, 3H), 2.50 (qd, J = 7.5, 0.9 Hz, 8H), 1.26 (t, J = 7.5 Hz, 12H).

[0062] 13 C NMR (101 MHz, CDCl3) δ 162.02, 156.48, 141.57, 136.09, 130.79,129.44, 128.76, 127.53, 127.01, 122.13, 116.03, 103.07, 62.77, 55.35, 35.03,24.15, 14.23.

[0063] The structure of palladium catalyst C2 is shown below:

[0064] .

[0065] Example 3

[0066] This embodiment provides a palladium catalyst C3, the preparation method of which includes the following steps:

[0067] Imidazole salt ligand L3 (1.0 mmol), potassium carbonate (12 mmol), and palladium dichloride (1.0 mmol) were added to 12 mL of N-methylimidazole and mixed at room temperature. The mixture was then heated to 90°C and stirred for 10 hours. After the reaction was completed, the liquid was removed under reduced pressure, and the crude product was dissolved in 5 mL of dichloromethane. Subsequently, 20 mL of n-hexane was added, and the resulting palladium complex precipitate was collected by filtration, washed with n-hexane (2 × 20 mL), and dried to obtain a grayish-white palladium catalyst powder C3 with a yield of 74%. The NMR C-H spectrum of palladium catalyst C3 is as follows:

[0068] 1 H NMR (400 MHz, CDCl3) δ 7.50 (tt, J = 1.5, 0.7 Hz, 1H), 7.12-7.08(m, 5H), 7.00 (dd, J = 5.6, 1.7 Hz, 1H), 6.94-6.90 (m, 4H), 6.85-6.81 (m,4H), 6.76 (dd, J = 8.8, 7.7 Hz, 2H), 3.82 (s, 6H), 3.72 (t, J = 0.7 Hz, 3H), 2.89 (hd, J = 6.8, 0.7 Hz, 4H), 1.28 (d, J = 6.9 Hz, 24H).

[0069] 13 C NMR (101 MHz, CDCl3) δ 162.02, 156.48, 144.25, 141.09, 130.79,129.44, 127.53, 127.24, 126.60, 122.13, 116.03, 103.07, 62.77, 55.35, 35.03,28.88, 24.04.

[0070] The structure of palladium catalyst C3 is shown below:

[0071] .

[0072] Example 4

[0073] This embodiment provides a dihexylfluorene-long-chain alkylaniline polymer, the preparation method of which includes the following steps:

[0074] 1 mmol of 4-dodecylaniline, 1 mmol of 2,7-dibromo-9,9-di-n-hexylfluorene, and 3 mmol of KO were added to the reactor. tBu, 0.01 mmol palladium catalyst C1, 3 mL toluene, nitrogen atmosphere, and reaction at 110 °C for 24 h. After the reaction, cool to room temperature, add dropwise to methanol solution to precipitate, wash 2-3 times with methanol solution, filter and air dry to obtain crude polymer; dissolve crude polymer in THF, stir at room temperature for 24 h, filter, add dropwise to methanol solution to precipitate, wash 2-3 times with methanol solution, filter and air dry to obtain yellow polymer, namely dihexylfluorene-long-chain alkylaniline polymer, yield 80%.

[0075] GPC analysis showed that the number-average molecular weight (Mn) was 95.60 kDa and the molecular weight distribution index (PDI) was 2.06. The structure of the dihexylfluorene-long-chain alkylaniline polymer is shown below:

[0076] .

[0077] Example 5

[0078] This embodiment provides a dihexylfluorene-long-chain alkylaniline polymer, the preparation method of which includes the following steps:

[0079] 1 mmol of 4-dodecylaniline, 1.05 mmol of 2,7-dibromo-9,9-di-n-hexylfluorene, and 3 mmol of KO were added to the reactor. t Bu, 0.01 mmol palladium catalyst C2, 3 mL toluene, nitrogen gas was introduced, and the reaction was carried out at 105 °C for 12 h. After the reaction was completed, the mixture was cooled to room temperature, added dropwise to a methanol solution to precipitate, washed 2-3 times with methanol solution, filtered, and air-dried to obtain crude polymer. The crude polymer was dissolved in THF, stirred at room temperature for 24 h, filtered, and the filtrate was added dropwise to a methanol solution to precipitate, washed 2-3 times with methanol solution, filtered, and air-dried to obtain a yellow polymer, namely dihexylfluorene-long-chain alkylaniline polymer, with a yield of 76%.

[0080] GPC analysis showed that the number-average molecular weight (Mn) was 56.12 kDa and the molecular weight distribution index (PDI) was 1.89. The structure of the dihexylfluorene-long-chain alkylaniline polymer is shown below:

[0081] .

[0082] Example 6

[0083] This embodiment provides a dihexylfluorene-long-chain alkylaniline polymer, the preparation method of which includes the following steps:

[0084] 1 mmol of 4-dodecylaniline, 1 mmol of 2,7-dibromo-9,9-di-n-hexylfluorene, and 3 mmol of KO were added to the reactor. tBu, 0.02 mmol palladium catalyst C1, 3 mL toluene, nitrogen atmosphere, and reaction at 115 °C for 30 h. After the reaction, cool to room temperature, add dropwise to methanol solution to precipitate, wash 2-3 times with methanol solution, filter and air dry to obtain crude polymer; dissolve crude polymer in THF, stir at room temperature for 24 h, filter, add dropwise to methanol solution to precipitate, wash 2-3 times with methanol solution, filter and air dry to obtain yellow polymer, namely dihexylfluorene-long-chain alkylaniline polymer, yield 74%.

[0085] GPC analysis showed that the number-average molecular weight (Mn) was 136.01 kDa and the molecular weight distribution index (PDI) was 3.12. The structure of the dihexylfluorene-long-chain alkylaniline polymer is shown below:

[0086] .

[0087] Example 7

[0088] This embodiment provides a dihexylfluorene-long-chain alkylaniline polymer, the preparation method of which includes the following steps:

[0089] 1 mmol of 4-octylaniline, 1 mmol of 2,7-dibromo-9,9-di-n-hexylfluorene, and 3 mmol of KO were added to the reactor. t Bu, 0.02 mmol palladium catalyst C3, 3 mL toluene, and nitrogen atmosphere were introduced, and the reaction was carried out at 110 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, added dropwise to a methanol solution to precipitate, washed 2-3 times with methanol solution, filtered, and air-dried to obtain a crude polymer. The crude polymer was dissolved in THF, stirred at room temperature for 24 h, filtered, and the filtrate was added dropwise to a methanol solution to precipitate, washed 2-3 times with methanol solution, filtered, and air-dried to obtain a yellow polymer, namely dihexylfluorene-long-chain alkylaniline polymer, with a yield of 78%.

[0090] GPC analysis showed that the number-average molecular weight (Mn) was 87.25 kDa and the molecular weight distribution index (PDI) was 2.25. The structure of the dihexylfluorene-long-chain alkylaniline polymer is shown below:

[0091] .

[0092] Example 8

[0093] This embodiment provides a dihexylfluorene-long-chain alkylaniline polymer, the preparation method of which includes the following steps:

[0094] 1 mmol of 4-hexylaniline, 1 mmol of 2,7-dibromo-9,9-di-n-hexylfluorene, and 3 mmol of KO were added to the reactor. tBu, 0.02 mmol palladium catalyst Cl, 3 mL toluene, nitrogen atmosphere, and reaction at 110 °C for 24 h. After the reaction, cool to room temperature, add dropwise to methanol solution to precipitate, wash 2-3 times with methanol solution, filter and air dry to obtain crude polymer; dissolve crude polymer in THF, stir at room temperature for 24 h, filter, add dropwise to methanol solution to precipitate, wash 2-3 times with methanol solution, filter and air dry to obtain yellow polymer, namely dihexylfluorene-long-chain alkylaniline polymer, yield 82%.

[0095] GPC analysis showed that the number-average molecular weight (Mn) was 78.54 kDa and the molecular weight distribution index (PDI) was 2.83. The structure of the dihexylfluorene-long-chain alkylaniline polymer is shown below:

[0096] .

[0097] Example 9

[0098] This embodiment provides a dihexylfluorene-long-chain alkylaniline polymer, the preparation method of which includes the following steps:

[0099] 1 mmol of 4-pentylaniline, 1 mmol of 2,7-dibromo-9,9-di-n-hexylfluorene, and 3 mmol of KO were added to the reactor. t Bu, 0.02 mmol palladium catalyst C2, 3 mL toluene, and nitrogen atmosphere were introduced, and the reaction was carried out at 110 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature, added dropwise to a methanol solution to precipitate, washed 2-3 times with methanol solution, filtered, and air-dried to obtain a crude polymer. The crude polymer was dissolved in THF, stirred at room temperature for 24 h, filtered, and the filtrate was added dropwise to a methanol solution to precipitate, washed 2-3 times with methanol solution, filtered, and air-dried to obtain a yellow polymer, namely dihexylfluorene-long-chain alkylaniline polymer, with a yield of 82%.

[0100] GPC analysis showed that the number-average molecular weight (Mn) was 71.89 kDa and the molecular weight distribution index (PDI) was 2.65. The structure of the dihexylfluorene-long-chain alkylaniline polymer is shown below:

[0101] .

[0102] Comparative Example 1

[0103] This comparative example provides a dihexylfluorene polymer, the preparation method of which includes the following steps:

[0104] 2 mL of distilled water, 1 mL of saturated Na₂CO₃ solution, 0.05 g of tetrabutylammonium bromide, 5 mL of toluene, 0.01 g of Pd(PPh₃)₄, and 0.25 g of 2-bromo-9,9-dihexylfluorene-7-boric acid were added to a reactor. Nitrogen gas was introduced, and the reaction was carried out at 80 °C for 72 h. After the reaction was completed, the mixture was cooled to room temperature and added dropwise to a methanol solution to precipitate. The precipitate was washed 2-3 times with methanol solution, filtered, and air-dried to obtain a crude polymer. The crude polymer was dissolved in THF, added dropwise to a methanol solution to precipitate, washed 2-3 times with methanol solution, filtered, and air-dried to obtain a yellow polymer, i.e., dihexylfluorene polymer, with a yield of 77%.

[0105] GPC analysis showed that the number-average molecular weight (Mn) was 73.58 kDa and the molecular weight distribution index (PDI) was 2.42. The structure of the dihexylfluorene polymer is shown below:

[0106] .

[0107] Performance testing: The fluorescence emission properties of the polymers obtained in Examples 4-9 and Comparative Example 1 were tested at different temperatures using THF as the solvent at a concentration of 0.01 mg / mL. The results are shown in Table 1 and... Figure 1 .

[0108] Table 1

[0109]

[0110] According to Table 1 and Figure 1 It can be seen that the fluorescence emission spectrum of the dihexylfluorene-long-chain alkylaniline polymer prepared in Examples 4-9 of the present invention has a narrow peak and a single peak, and the emission color is pure, which meets the application requirements of pure color light-emitting devices. At the same time, when C8 alkyl chain and C12 alkyl chain substituted aniline are introduced into the polymer, even under high temperature environment, the fluorescence emission spectrum of the polymer still has a narrow peak and a single peak, and the emission wavelength remains almost unchanged, that is, the emission color is pure and stable.

[0111] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this application specification, they can still modify or make equivalent substitutions to the specific implementation of the present invention, but these modifications or changes do not depart from the protection scope of the pending claims of the present invention.

Claims

1. A dihexylfluorene-long-chain alkylaniline polymer, characterized in that, The structural formula of the dihexylfluorene-long-chain alkylaniline polymer is shown in Formula (II): Equation (II); Among them, the number average molecular weight is 50kDa~150kDa, and the PDI is 1.5-3.

5.

2. The dihexylfluorene-long-chain alkylaniline polymer according to claim 1, characterized in that, Its raw materials include: long-chain alkyl-substituted aniline and 2,7-dibromo-9,9-di-n-hexylfluorene .

3. The method for preparing the dihexylfluorene-long-chain alkylaniline polymer according to any one of claims 1 to 2, characterized in that, Includes the following steps: Long-chain alkyl-substituted aniline is produced under the action of palladium catalyst and auxiliaries. and 2,7-dibromo-9,9-di-n-hexylfluorene The reaction occurs to obtain the dihexylfluorene-long-chain alkylaniline polymer.

4. The method for preparing the dihexylfluorene-long-chain alkylaniline polymer according to claim 3, characterized in that, The molar ratio of the long-chain alkyl-substituted aniline to the 2,7-dibromo-9,9-di-n-hexylfluorene is 1:1 to 1.

1.

5. The method for preparing the dihexylfluorene-long-chain alkylaniline polymer according to claim 3, characterized in that, The molar ratio of the palladium catalyst to the 2,7-dibromo-9,9-di-n-hexylfluorene is 0.005~0.02:1; And / or, the structure of the palladium catalyst is shown in formula (VI): Equation (VI), where R 1 R 2 It can be hydrogen, methyl, ethyl, or isopropyl independently, and R 1 R 2 They are not both hydrogen.

6. The method for preparing the dihexylfluorene-long-chain alkylaniline polymer according to claim 3, characterized in that, The reaction is carried out at a temperature of 100~120℃ for a time of 12~36 hours. And / or, the reaction is carried out in an inert gas atmosphere; And / or, the reaction may include a post-processing step after it is completed.

7. The method for preparing the dihexylfluorene-long-chain alkylaniline polymer according to claim 6, characterized in that, The post-processing steps include a methanol precipitation step.

8. The method for preparing the dihexylfluorene-long-chain alkylaniline polymer according to claim 3, characterized in that, The additives include organic bases and solvents.

9. The method for preparing the dihexylfluorene-long-chain alkylaniline polymer according to claim 8, characterized in that, The organic base is potassium tert-butoxide; And / or, the molar ratio of the organic base to the 2,7-dibromo-9,9-di-n-hexylfluorene is 2 to 4:

1.

10. The method for preparing the dihexylfluorene-long-chain alkylaniline polymer according to claim 8, characterized in that, The solvent is toluene; And / or, the ratio of the solvent to the 2,7-dibromo-9,9-di-n-hexylfluorene is 2 L to 4 L: 1 mol.

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