A method for preparing chiral nanographene

Abstract

The application discloses a preparation method of chiral nanographene and belongs to the technical field of organic synthesis preparation. In the application, 2,3-dibromonaphthalene is used as a starting material, and is coupled with 4-tert-butyl phenylboronic acid to obtain compound 1. Compound 1 is subjected to bromination to obtain compound 2. Compound 2 is coupled with methyl acrylate to obtain compound 3. Compound 3 is subjected to reduction, dehydration, acylation and a Friedel-Crafts reaction to obtain compound 4. Compound 4 is subjected to nucleophilic addition of 4-tert-butyl phenylmagnesium bromide, dehydration and finally radical coupling oxidation dimerization to obtain chiral nanographene. Compared with the reported methods, the preparation method of the application has mild and safe reaction conditions, good production efficiency and selectivity, and is a novel and efficient method for preparing chiral nanographene.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology and is a method for preparing chiral graphene nanoparticles. Background Technology

[0002] Graphene nanoparticles, as a class of graphene fragments with a size between 1 and 100 nm, have the potential to be applied to next-generation semiconductor materials. Chiral graphene nanoparticles with helical structures have become a research hotspot due to their unique optical activity. Current classical methods for synthesizing chiral graphene nanoparticles, such as Brønsted acid-catalyzed alkyne cyclization and iridium-catalyzed alkyne cyclization, typically require complex substrate pre-preparation, involve cumbersome steps, require noble metal catalysis, and have low overall yields. Summary of the Invention

[0003] Purpose of the invention: To address the problems existing in the prior art, this invention provides a green, inexpensive, efficient, and easy-to-operate method for preparing chiral graphene nanoparticles. This invention not only provides mild reaction conditions but also improves the safety and production efficiency of the reaction, making it a novel and efficient method for preparing chiral graphene nanoparticles.

[0004] Technical solution: To achieve the above objectives, the present invention provides a method for preparing chiral graphene nanoparticles, comprising the following steps:

[0005] Step 1: Using 2,3-dibromonaphthalene and 4-tert-butylphenylboronic acid as raw materials, a compound 1 with the structural formula shown in (1) was obtained by coupling.

[0006]

[0007] Step 2: Compound 1 is brominated with liquid bromine to obtain compound 2 with the structural formula shown in (2):

[0008]

[0009] Step 3: Compound 2 is coupled with methyl acrylate to obtain compound 3 with the structural formula shown in (3):

[0010]

[0011] Step 4: Compound 3 undergoes (1) reduction, (2) hydrolysis, (3) acylation, and (4) Friedel-Crafts reaction to obtain compound 4 with the structural formula shown in (4):

[0012]

[0013] Step 5: Compound 4 and 4-tert-butylphenyl magnesium bromide undergo nucleophilic addition (1), followed by dehydration (2), and finally free radical coupling oxidative dimerization (3) to obtain chiral graphene nanoparticles with the structural formula shown in (5):

[0014]

[0015] In step one, the solvent used to prepare compound 1 is 1,4-dioxane or toluene; the base used is one of sodium hydroxide, potassium carbonate, or cesium carbonate; the catalyst used is tetrakis(triphenylphosphine)palladium; the reaction temperature is 70–90℃; and the reaction time is 12–16 hours.

[0016] In step one, when preparing compound 1, the molar ratio of 2,3-dibromonaphthalene, 4-tert-butylphenylboronic acid, catalyst, and base is 1:2–3:0.1:5.

[0017] Preferably, the solvent used in step one for preparing compound 1 is 1,4-dioxane; the base used is sodium hydroxide; the catalyst used is tetrakis(triphenylphosphine)palladium; the reaction temperature is 80°C; and the reaction time is 14 hours. In step one for preparing compound 1, the molar ratio of 2,3-dibromonaphthalene, 4-tert-butylphenylboronic acid, base, and catalyst is 1:3:0.1:5.

[0018] In step two, when preparing compound 2, the molar ratio of compound 1 to liquid bromine is 1:0.9–1.0; the solvent used is dichloromethane or acetonitrile; the reaction temperature is room temperature; and the reaction time is 0.5–1 hour.

[0019] Preferably, in step two, when preparing compound 2, the molar ratio of compound 1 to liquid bromine is 1:1; the solvent used is dichloromethane; the reaction temperature is room temperature; and the reaction time is 1 hour.

[0020] In step three, when preparing compound 3, the molar ratio of compound 2, methyl acrylate, and [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride is 1:3–5:0.1–0.2; the solvent used is N,N-dimethylformamide; the base used is triethylamine; the reaction temperature is 100–110℃; and the reaction time is 14–18 hours.

[0021] Preferably, in step three, when preparing compound 3, the molar ratio of compound 2, methyl acrylate, and [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride is 1:5:0.2; the solvent used is N,N-dimethylformamide; the base used is triethylamine; the reaction temperature is 110℃; and the reaction time is 16 hours.

[0022] In step four, when preparing compound 4, the solvent used in reaction (1) is an equal volume of tetrahydrofuran and methanol, the molar ratio of compound 3, sodium borohydride and nickel chloride hexahydrate is 1:5–10:1, the reaction temperature is room temperature, and the reaction time is 0.3–0.5 hours; the base used in reaction (2) is one of sodium hydroxide, potassium carbonate and cesium carbonate, the reaction solvent is tetrahydrofuran and ethanol, the reaction temperature is room temperature, and the reaction time is 10–14 hours; the solvent used in reaction (3) is dichloromethane, the reaction temperature is 40–45℃, and the reaction time is 2.5–3 hours; the solvent used in reaction (4) is dichloromethane, the reaction temperature is -50–-40℃, and the reaction time is 0.5–1 hours.

[0023] As a preferred embodiment, in step four, when preparing compound 4, the solvent used in reaction (1) is tetrahydrofuran and methanol in a volume ratio of 1:1; the molar ratio of compound 3, sodium borohydride, and nickel chloride hexahydrate is 1:8:1; the reaction temperature is room temperature; and the reaction time is 0.5 hours; the base used in reaction (2) is sodium hydroxide; the reaction solvent is tetrahydrofuran and ethanol; the reaction temperature is room temperature; and the reaction time is 12 hours; the solvent used in reaction (3) is dichloromethane; the reaction temperature is 40°C; and the reaction time is 3 hours; the solvent used in reaction (4) is dichloromethane; the reaction temperature is -50°C; and the reaction time is 1 hour.

[0024] In step five, when preparing compound 5, the molar ratio of compound 4, 4-tert-butylphenyl magnesium bromide, lithium chloride, and cerium chloride in reaction (1) is 1:2–3:2–3:2–3, the reaction solvent is tetrahydrofuran, the reaction temperature is -78–-50℃, and the reaction time is 1–2 hours; the solvent used in reaction (2) is toluene, the reaction temperature is 80–100℃, and the reaction time is 0.3–0.5 hours; the solvent used in reaction (3) is toluene, the reaction temperature is 30–80℃, and the reaction time is 0.5–1 hours.

[0025] As a preferred embodiment, in step five, when preparing compound 5, the molar ratio of compound 4, 4-tert-butylphenyl magnesium bromide, lithium chloride, and cerium chloride in reaction (1) is 1:3:3:3, the reaction solvent is tetrahydrofuran, the reaction temperature is -78℃, and the reaction time is 1 hour; the solvent used in reaction (2) is toluene, the reaction temperature is 90℃, and the reaction time is 0.5 hours; the solvent used in reaction (3) is toluene, the reaction temperature is 80℃, and the reaction time is 1 hour.

[0026] The chiral graphene nanoparticles of the present invention have the structure shown in formula (5):

[0027]

[0028] The steric hindrance caused by the two adjacent tert-butylphenyl groups results in a twist angle of -24.3° in the bay region (C1–C2–C3–C4) of compound 5. This stereorepulsion causes conformational distortion of the two benzene rings, preventing them from maintaining a coplanar state, thus giving compound 5 chirality.

[0029] The application of chiral graphene nanoparticles described in this invention in semiconductor materials.

[0030] Preferably, the method for preparing the chiral graphene nanoparticles includes the following steps:

[0031] All reactions were carried out under a nitrogen atmosphere.

[0032] Step 1: Take a suitable Schlenk flask and add 2,3-dibromonaphthalene, 4-tert-butylphenylboronic acid, tetra(triphenylphosphine)palladium, sodium hydroxide solution, and 1,4-dioxane. React at 80°C for 14 hours. After the reaction solution cools to room temperature, immerse it in water, extract with dichloromethane, collect the organic phase, and evaporate to dryness. Column chromatography (petroleum ether) yields compound 1.

[0033] Step 2: Take a suitable two-necked flask, add compound 1, dissolve it in dichloromethane, then slowly add a solution of liquid bromine in dichloromethane, and react at room temperature for 1 hour. Extract with dichloromethane and saturated Na2S2O3 solution, collect the organic phase and evaporate to dryness. Column chromatography (petroleum ether) yields compound 2.

[0034] Step 3: Take a suitable Schlenk flask and add compound 2, [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride, triethylamine, N,N-dimethylformamide, and methyl acrylate. React at 110°C for 16 hours. After the reaction solution cools to room temperature, pour it into water, extract with ethyl acetate, collect the organic phase, and evaporate to dryness. Column chromatography (petroleum ether / ethyl acetate = 15 / 1) yields compound 3.

[0035] Step 4: Reaction (1): Take a suitable round-bottom flask, add compound 3, dissolve it in tetrahydrofuran and methanol, then add sodium borohydride and nickel chloride hexahydrate, and react at room temperature for 0.5 hours. Pour the reaction solution into water, extract with ethyl acetate, collect the organic phase and evaporate to dryness. Reaction (2): Take a suitable two-necked flask, add the crude product of (1), dissolve it in tetrahydrofuran, then add ethanol and sodium hydroxide solution, and react at room temperature for 12 hours. Pour the reaction solution into water, add an appropriate amount of dilute hydrochloric acid, extract with ethyl acetate, collect the organic phase and evaporate to dryness. Reaction (3): Take a suitable two-necked flask, add the crude product of (2), dissolve it in dichloromethane, then add oxaloyl chloride, and react at 40°C for 3 hours. Remove the solvent and excess oxaloyl chloride by vacuum distillation to obtain a pale yellow solid, which can be used directly in the next reaction. Reaction (4): Dissolve the crude product of the previous step in dichloromethane. Add titanium tetrachloride at -50°C and maintain the reaction at -50°C for 1 hour. The reaction solution was poured into water, extracted with dichloromethane, and the organic phase was collected and evaporated to dryness. Column chromatography (petroleum ether / ethyl acetate = 15 / 1) yielded compound 4.

[0036] Step 5: Reaction (1): Take a suitable Schlenk flask, add compound 4, lithium chloride and cerium chloride, dissolve in tetrahydrofuran, add 4-tert-butylphenyl magnesium bromide at -78℃, and react at -78℃ for 1 hour. Pour the reaction solution into water, extract with ethyl acetate, collect the organic phase and evaporate to dryness. Reaction (2): Take a suitable two-necked flask, add the crude product from (1) and p-toluenesulfonic acid monohydrate, dissolve in toluene, and react at 90℃ for 0.5 hours. After the reaction is complete, purify the product by silica gel column chromatography (eluent is toluene), and remove the solvent by vacuum distillation. Reaction (3): Dissolve the crude product from the previous step in toluene, then add tetrachlorobenzoquinone, and react at 80℃ for 1 hour. After the reaction is complete, remove the solvent by vacuum distillation, and obtain compound 5 by column chromatography (petroleum ether / dichloromethane = 8 / 1).

[0037] Furthermore, in step one, the molar ratio of 2,3-dibromonaphthalene to 4-tert-butylphenylnaphthalene is 1:3.

[0038] Furthermore, the role of the saturated Na2S2O3 solution in step two is to remove excess Br2.

[0039] Furthermore, in step three, the volume ratio of triethylamine to N,N-dimethylformamide is 1:3.

[0040] Furthermore, in step four, the volume ratio of tetrahydrofuran to methanol in reaction (1) is 1:1; and the volume ratio of ethanol to sodium hydroxide solution in reaction (2) is 1:2.

[0041] Furthermore, in step five, the role of p-toluenesulfonic acid monohydrate in reaction (1) is to utilize its acidity to promote the dehydration and alkenylation reaction of alcohol.

[0042] The synthetic route of this invention is shown below:

[0043]

[0044] This invention provides a method for synthesizing chiral graphene nanoparticles. Starting with 2,3-dibromonaphthalene, it is first coupled with 4-tert-butylphenylboronic acid to obtain compound 1; compound 1 is brominated to obtain compound 2; compound 2 is coupled with methyl acrylate to obtain compound 3; compound 3 undergoes reduction, dehydration, acylation, and Friedel-Crafts reaction to obtain compound 4; compound 4 undergoes nucleophilic addition with 4-tert-butylphenyl magnesium bromide, followed by dehydration and free radical coupling oxidative dimerization to obtain chiral graphene nanoparticles. This invention features mild reaction conditions, improving reaction safety and production efficiency, and represents a novel and efficient method for preparing chiral graphene nanoparticles.

[0045] In this invention, by introducing a large-volume aryl group (4-tert-butylphenyl), the radical reaction at the α-position of the finasteride radical is selectively suppressed, causing its σ-dimerization to occur only at the α1 or α2 position, ultimately generating chiral nanographene.

[0046] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0047] 1. This invention precisely controls the dimerization sites of finasteride free radicals through steric hindrance effect, providing a new synthetic method for preparing chiral graphene nanoparticles.

[0048] 2. The preparation method of the present invention has mild reaction conditions, inexpensive and readily available raw materials, and low reaction cost.

[0049] 3. The preparation method of the present invention has a high overall yield and the reaction has unique regioselectivity.

[0050] 4. Compound 5 prepared in this invention has the potential function of being a p-type organic semiconductor. Furthermore, this compound exhibits good and uniform staining effects, making it suitable as an organic fluorescent dye for application in the biomedical field. Attached Figure Description

[0051] Figure 1 The UV and fluorescence spectra of compound 5 are shown.

[0052] Figure 2 This is a cyclic voltammetry diagram of compound 5.

[0053] Figure 3 (a) Single crystal structure of compound 5, (b) Packing structure of compound 5.

[0054] Figure 4 The CD spectra of (P)-5 and (M)-5 in chloroform solution are shown.

[0055] Figure 5 The structures of two graphene fragment products are shown. Detailed Implementation

[0056] The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the descriptions in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims.

[0057] Example 1

[0058] The synthesis method of chiral graphene nanoparticles includes the following steps:

[0059] All reactions were carried out under a nitrogen atmosphere.

[0060] Synthesis of Compound 1

[0061]

[0062] 2,3-Dibromonaphthalene (286 mg, 1 mmol), 4-tert-butylphenylboronic acid (534 mg, 3 mmol), tetrakis(triphenylphosphine)palladium (115.6 mg, 0.1 mmol), 2 mol / L sodium hydroxide solution (2.5 mL), and 1,4-dioxane (8 mL) were added to a Schlenk flask and reacted at 80 °C for 14 hours. After the reaction solution cooled to room temperature, it was poured into water and extracted three times with 30 mL of dichloromethane. The organic phase was dried over anhydrous MgSO4, filtered, and the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography (petroleum ether) to give a white solid (338 mg, 86%). 1 H NMR (600MHz, CDCl3, ppm): δ7.89 (dd, J=12.5, 6.5Hz, 2H), 7.87 (s, 2H), 7.50 (dd, J=12.5,6.5Hz,4H),7.28(d,J=8.3Hz,4H),7.17(d,J=8.3Hz,4H),1.32(s,18H). 13 C NMR (150MHz, CDCl3, ppm): δ150.0,139.6,139.1,133.2,130.1,129.8,128.1,126.6,125.2,34.8,31.6.HRMS(AP-MALDI)m / z:[M] + Calcd.for C 30 H 32 392.2497; Found 392.2499.

[0063] Synthesis of Compound 2

[0064]

[0065] Compound 1 (393 mg, 1 mmol) and anhydrous dichloromethane (10 mL) were added to a two-necked flask, followed by the slow addition of a dichloromethane solution of liquid bromine (0.1 mL, 1 mmol). The reaction was allowed to proceed at room temperature for 1 hour. The reaction was quenched with saturated Na₂S₂O₃ solution, and the mixture was extracted three times with 30 mL of dichloromethane. The organic phase was dried over anhydrous MgSO₄, filtered, and the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography (pure petroleum ether) to give compound 2 (329 mg, 70%) as a white solid. 1 HNMR (600MHz, CDCl3, ppm): δ8.41(d,J=8.5,Hz,1H),7.885-7.87(m,2H),7.62(t,J=7.7Hz,1H),7.56(t,J=7.5Hz,1H) ,7.24(d,J=8.5Hz,2H),7.14(d,J=8.1Hz,2H),7.04(d,J=7.6Hz,2H),6.98(d,J=8.2Hz,2H),1.29(s,9H),1.25(s,9H). 13 C NMR (150MHz, CDCl3, ppm): δ149.9,149.4,141.3,140.8,138.4,138.3,133.7,131.8,130.5,129.5, 128.5,128.3,128.2,127.6,126.9,124.4,124.4,34.6,34.5,31.5,31.4.HRMS(MALDI)m / z:[M+NH4] + Calcd.for C 30 H 35 NBr488.1947; Found488.1946.

[0066] Synthesis of Compound 3

[0067]

[0068] Compound 2 (954 mg, 2.0 mmol), [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) dichloride (293 mg, 0.4 mmol), triethylamine (3 mL), N,N-dimethylformamide (9 mL), and methyl acrylate (0.88 mL, 10 mmol) were added to a Schlenk flask, and the reaction mixture was heated to 110 °C and reacted for 16 hours. After the reaction mixture cooled to room temperature, it was poured into water and extracted three times with 30 mL of ethyl acetate. The organic phase was dried over anhydrous MgSO4, the solution was filtered, and the solvent was removed by vacuum distillation. Finally, the crude product was purified by silica gel column chromatography (petroleum ether / ethyl acetate = 15 / 1) to give green solid 3 (733 mg, 76%). 1 HNMR (600MHz, CDCl3, ppm): δ8.23 (dd, J=6.4, 3.5Hz, 1H), 7.92-7.89 (m, 3H), 7.54 (dd, J=6.4, 3.3Hz, 2H), 7.17 (d, J=8.4Hz, 1H), 7 .14(d,J=8.5Hz,2H),6.98(d,J=8.5Hz,2H),6.92(d,J=8.4Hz,2H),6.12(d,J=16.4Hz,1H),3.75(s,3H),1.27(s,9H),1.25(s,9H). 13 C NMR (150MHz, CDCl3, ppm): δ200.0,141.3,141.2,141.1,140.6,140.5,140.44,140.35,140.0,139.74,139.67,139.6 5,134.2,134.0,133.6,133.43,133.37,29.4,29.0,23.0,22.94,22.90,14.28,14.26,14.2.HRMS(AP-MALDI)m / z:[M] + Calcd.for C 34 H 36 O2476.2710; Found476.2705.

[0069] Synthesis of Compound 4

[0070]

[0071] (1) Compound 3 (704 mg, 1.478 mmol), tetrahydrofuran (6 mL), and methanol (6 mL) were added to a round-bottom flask. Sodium borohydride (447.5 mg, 11.828 mmol) and nickel chloride hexahydrate (351.3 mg, 1.478 mmol) were added under ice bath conditions, and the mixture was reacted at room temperature for 0.5 hours. The reaction mixture was poured into water, filtered, and the filtrate was extracted three times with 30 mL of ethyl acetate. The organic phase was dried over anhydrous MgSO4, filtered, and the solvent was removed by vacuum distillation to obtain a white solid, which was used directly in the next step of the reaction.

[0072] (2) In a two-necked flask, add all the obtained white solid, tetrahydrofuran (10 mL), ethanol (3 mL), and 2 mol / L sodium hydroxide solution (5.9 mL), and react at room temperature for 12 hours. After the reaction is complete, add 1 mol / L hydrochloric acid (12 mL) to the reaction solution, mix thoroughly, and allow the generated carboxylate ions to combine with protons to obtain a solution of carboxylic acid products. Dilute the reaction mixture with water, extract three times with 30 mL of ethyl acetate, dry the organic phase with anhydrous MgSO4, filter, and remove the solvent by vacuum distillation to obtain a white solid, which can be directly used in the next step of the reaction.

[0073] (3) Add the crude product obtained in the previous step, anhydrous dichloromethane (10 mL), and oxalyl chloride (5.6 mL, 66.51 mmol) to a two-necked flask, and reflux at 40 °C for 3 hours. After the reaction is complete, remove the solvent and excess oxalyl chloride by vacuum distillation to obtain a pale yellow solid, which can be used directly in the next step of the reaction.

[0074] (4) The crude product from the previous step was dissolved in anhydrous dichloromethane (10 mL). Titanium tetrachloride (0.81 mL, 7.39 mmol) was added at -50 °C, and the reaction was carried out at -50 °C for 1 hour. The reaction solution was poured into water and extracted three times with 30 mL of dichloromethane. The organic phase was dried over anhydrous MgSO4, filtered, and the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography (petroleum ether / ethyl acetate = 15 / 1) to give a pale yellow solid compound 4 (571 mg, yield 87%). 1 HNMR (600MHz, CDCl3, ppm): δ8.23(d,J=7.3Hz,1H),8.11(d,J=8.2Hz,1H),7.86(s,1H),7.63(t,J=7.7,2 .0Hz,1H),7.25(d,J=8.3Hz,2H),7.16(d,J=8.5Hz,2H),7.00(t,J=7.6Hz,4H),1.29(s,9H),1.26(s,9H). 13C NMR (150MHz, CDCl3, ppm): δ199.0,149.8,149.4,141.2,139.3,138.6,136.4,134.2,132.7,131.2,131.1,130.2 ,130.1,129.6,127.0,125.9,125.4124.7,124.4,38.7,34.6,34.5,31.5,31.4,27.4.HRMS(AP-MALDI)m / z:[M+H] + Calcd.for C 33 H 35 O447.2682; Found447.2675.

[0075] Synthesis of Compound 5

[0076]

[0077] (1) Lithium chloride (68 mg, 1.612 mmol), cerium trichloride (398 mg, 1.612 mmol), compound 4 (240 mg, 0.537 mmol), and anhydrous tetrahydrofuran (5 mL) were added to a Schlenk flask. 4-tert-butylphenyl magnesium bromide (3.2 mL, 1.612 mmol) was added dropwise at -78 °C, and the reaction was carried out at -78 °C for 1 hour. The reaction solution was poured into water, extracted three times with 30 mL of ethyl acetate, dried, filtered, and the solvent was removed under reduced pressure to obtain a yellow-green oily liquid, which could be used directly in the next step of the reaction.

[0078] (2) Add all the crude product obtained in the previous step, a catalytic amount of p-toluenesulfonic acid monohydrate, and toluene (3 mL) to a two-necked flask, and react at 90 °C for 0.5 hours. After the reaction is complete, purify the product by column chromatography under nitrogen (stationary phase: Florisil, mobile phase: toluene). Remove the solvent by vacuum distillation and proceed to the next step of the reaction.

[0079] (3) Tetrachlorobenzoquinone (330 mg, 1.243 mmol) and toluene (3 mL) were added to the Schlenk flask containing the product from the previous step, and the mixture was reacted at 80 °C for 1 hour. The solvent was removed by vacuum distillation, and the crude product was purified by silica gel column chromatography (petroleum ether / dichloromethane = 8 / 1) to give an orange solid compound 5 (120 mg, 40%). 1H NMR (600MHz, CDCl3, ppm): δ8.23 (d, J = 7.3Hz, 1H), 8.11 (d, J = 8.2Hz, 1H), 7.86 (s, 1H), 7.63 (t, J = 7.7, 2. 0Hz,1H),7.25(d,J=8.3Hz,2H),7.16(d,J=8.5Hz,2H),7.00(t,J=7.6Hz,4H),1.29(s,9H),1.26(s,9H). 13 CNMR (150MHz, CDCl3, ppm): δ150.3,149.6,148.2,138.6,138.2,138.1,137.4,137.1,133.0,132.4,132.0,130.5,129.5,128.6,127. 8,127.1,125.6,125.5,125.3,125.1,124.5,124.5,123.7,122.8,122.6,34.9,34.6,34.3,31.7,31.6,31.4.HRMS(AP-MALDI)m / z:[M] + Calcd.for C 86 H 86 1118.6724; Found 1118.6696.

[0080] The preparation method of this invention not only has a higher overall yield than the prior art (Journal of the American Chemical Society, 2017, 139(37): 13102–13109; Angewandte Chemie International Edition, 2024, 63, No. e202404849; The Journal of Organic Chemistry, 2024, 89(7): 5159–5163.), but also the reaction of this invention may involve two selective products 5 and 5a ( Figure 5 However, in this invention, only product 5 was detected, thus exhibiting regional selectivity.

[0081] Example 2

[0082] In chloroform solution (1.0 × 10⁻⁶) -5 The photophysical properties of compound 5 were studied in M). Figure 1 As shown, the maximum absorption peak is at 504 nm, the strongest emission peak is at 538 nm, and the fluorescence quantum yield is 40%. This fluorescence property may have potential applications in fields such as biolabeling, chemical sensing, or materials science.

[0083] Cyclic voltammetry was performed under a nitrogen atmosphere. A standard three-electrode system was used: the working electrode was a 3mm disc-shaped glassy carbon electrode polished with alumina, the reference electrode was Ag / AgNO3, and the counter electrode was a platinum wire electrode. The electrolyte system consisted of 0.1M n-butyl hexafluorophosphate (...). n The electrolyte consists of a dichloromethane solution containing BuNPF6, and contains compound 5. The scan rate is 50 mV. -1 .

[0084] like Figure 2 As shown, compound 5 exhibits two reversible oxidation potentials of 0.24 V and 0.68 V (relative to ferrocene / ferrocene cations, ferrocene / ferrocene ions (FcCp2)). + The potential in the form of / FcCp2) is -5.1 eV, based on an approximate calculation neglecting solvent effects, using the work function of NHE (4.46 eV) and the electrochemical potential relative to NHE (0.64 V). (Reference: Adv. Mater. 2011, 23, 2367–2371.). Based on the first oxidation potential, the highest occupied molecular orbital (HOMO) of compound 5 is calculated to be -5.34 eV, indicating its potential function as a p-type organic semiconductor.

[0085] Meanwhile, the single-crystal structure of compound 5 shows that due to space crowding caused by two adjacent 4-tert-butylphenyl substituents, a twist angle of -24.3° is generated in the bay region (C1–C2–C3–C4). Figure 3 a). In the crystal, compound 5 exists as a pair of enantiomers, which form a dimer and then stack in a slip columnar manner. Figure 3 b) further demonstrates its potential as an organic semiconductor.

[0086] Example 3

[0087] Using Daicel Compound 5 was chirally resolved using an IH chiral column (0.46 cm × 25 cm) and a Shimadzu LC-20 AT HPLC system with methanol / dichloromethane = 4 / 1 as the eluent and a flow rate of 1 mL / min. The two chiral optically active components obtained were then prepared into 1.0 × 10⁻⁶ cells / mL. -5 The chloroform solution of M was tested for its circular dichroism (CD) chromatogram. See below. Figure 4 As shown, the CD spectra of these two chiral optical rotators exhibit a mirror-symmetric relationship, thus demonstrating chiral luminescence properties. The chiral graphene nanofragments prepared in this invention can be used as chiral optical materials.

[0088] Comparative Example 1

[0089] Comparative Example 1 follows the preparation method of Example 1, except that replacing liquid bromine with NBS or aluminum bromide does not result in a reaction. In Compound 2 of Example 1 of this invention, the use of liquid bromine can achieve a yield of 70%.

Claims

1. A method for preparing chiral graphene nanoparticles, characterized in that: Includes the following steps, Step 1: Using 2,3-dibromonaphthalene and 4-tert-butylphenylboronic acid as raw materials, a compound 1 with the structural formula shown in (1) was obtained by coupling. Step 2: Compound 1 is brominated with liquid bromine to obtain compound 2 with the structural formula shown in (2): Step 3: Compound 2 is coupled with methyl acrylate to obtain compound 3 with the structural formula shown in (3): Step 4: Compound 3 undergoes (1) reduction, (2) hydrolysis, (3) acylation, and (4) Friedel-Crafts reaction to obtain compound 4 with the structural formula shown in (4): Step 5: Compound 4 undergoes nucleophilic addition with 4-tert-butylphenyl magnesium bromide (1), followed by dehydration (2), and finally free radical coupling oxidative dimerization (3) to obtain chiral graphene nanoparticles with the structural formula shown in (5):

2. The method for preparing chiral graphene nanoparticles according to claim 1, characterized in that: In step one, the solvent used to prepare compound 1 is 1,4-dioxane or toluene; the base used is one of sodium hydroxide, potassium carbonate, or cesium carbonate; the catalyst used is tetrakis(triphenylphosphine)palladium; the reaction temperature is 70–90℃; and the reaction time is 12–16 hours.

3. The method for preparing chiral graphene nanoparticles according to claim 2, characterized in that: In step one, when preparing compound 1, the molar ratio of 2,3-dibromonaphthalene, 4-tert-butylphenylboronic acid, catalyst, and base is 1:2–3:0.1:

5.

4. The method for preparing chiral graphene nanoparticles according to claim 1, characterized in that, In step two, when preparing compound 2, the molar ratio of compound 1 to liquid bromine is 1:0.9–1.0; the solvent used is dichloromethane or acetonitrile; the reaction temperature is room temperature; and the reaction time is 0.5–1 hour.

5. The method for preparing chiral graphene nanoparticles according to claim 1, characterized in that, In step three, when preparing compound 3, the molar ratio of compound 2, methyl acrylate, and [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride is 1:3–5:0.1–0.2; the solvent used is N,N-dimethylformamide; the base used is triethylamine; the reaction temperature is 100–110℃; and the reaction time is 14–18 hours.

6. The method for preparing chiral graphene nanoparticles according to claim 1, characterized in that, In step four, when preparing compound 4, the solvent used in reaction (1) is an equal volume of tetrahydrofuran and methanol, the molar ratio of compound 3, sodium borohydride and nickel chloride hexahydrate is 1:5–10:1, the reaction temperature is room temperature, and the reaction time is 0.3–0.5 hours; the base used in reaction (2) is one of sodium hydroxide, potassium carbonate and cesium carbonate, the reaction solvent is tetrahydrofuran and ethanol, the reaction temperature is room temperature, and the reaction time is 10–14 hours; the solvent used in reaction (3) is dichloromethane, the reaction temperature is 40–45℃, and the reaction time is 2.5–3 hours; the solvent used in reaction (4) is dichloromethane, the reaction temperature is -50–-40℃, and the reaction time is 0.5–1 hours.

7. The method for preparing chiral graphene nanoparticles according to claim 1, characterized in that, In step five, when preparing compound 5, the molar ratio of compound 4, 4-tert-butylphenyl magnesium bromide, lithium chloride, and cerium chloride in reaction (1) is 1:2–3:2–3:2–3. The reaction solvent is tetrahydrofuran, the reaction temperature is -78–-50℃, and the reaction time is 1–2 hours. The solvent used in reaction (2) is toluene, the reaction temperature is 80–100℃, and the reaction time is 0.3–0.5 hours. The solvent used in reaction (3) is toluene, the reaction temperature is 30–80℃, and the reaction time is 0.5–1 hours.

8. A chiral graphene nanoparticle, characterized in that, The structure of the chiral graphene nanoparticles is shown in formula (5):

9. The application of the chiral graphene nanoparticles as described in claim 8 in semiconductor materials.

10. The application of the chiral graphene nanomaterial according to claim 8, preferably in chiral optical materials.

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