Synthesis method and application of asymmetric 1, 10-phenanthroline

Abstract

The invention relates to the technical field of chemical synthesis, in particular to a synthesis method and application of asymmetric 1, 10-phenanthroline. The synthesis method of the asymmetric 1, 10-phenanthroline, provided by the invention, comprises the following steps: reacting 8-aminoquinoline and crotonaldehyde under the acidic condition and the catalytic action of NaI to obtain an intermediate 1; carrying out oxidation reaction on the intermediate 1 under an acidic condition to obtain an intermediate 2; and reacting the intermediate 2 with phosphorus oxyhalide to obtain the asymmetric 1, 10-phenanthroline. According to the synthesis method of the asymmetric 1, 10-phenanthroline, through three-step efficient reaction, the synthesis period is short, the production efficiency is high, the used raw materials are easy to obtain and low in cost, a convenient and efficient synthesis means is provided for researchers, and the asymmetric 1, 10-phenanthroline modification method and substrate range are widened; meanwhile, the method is suitable for large-scale industrial production and meets the large demand of the market on the phenanthroline derivative.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, specifically to a method for synthesizing and applying asymmetric 1,10-phenanthroline. Background Technology

[0002] 1,10-phenanthroline is an important co-ligand. Its molecule possesses a coplanar 14-π electronic structure, exhibiting good stability. As a highly efficient electron donor, it plays a crucial functional ligand role in catalysis, materials science, biomedicine, energy, and sensors. Furthermore, 1,10-phenanthroline possesses excellent modifiability, and its modified compounds play important roles in numerous fields.

[0003] Asymmetric o-phenanthroline ligands exhibit significant advantages in multiple fields due to their unique structural characteristics and excellent coordination ability: 1. In catalysis, asymmetric o-phenanthroline ligands demonstrate high efficiency, good tolerance, and excellent enantiomeric and diastereoselectivity; 2. In lanthanide luminescence, asymmetric ligands can reduce energy loss and improve luminescence intensity and lifetime through their unique structural properties; 3. In radiative deexcitation, asymmetric complexes exhibit higher efficiency than symmetric complexes during radiative deexcitation, which helps improve the performance of luminescent materials; 4. In lanthanum-actinium separation, asymmetric ligands, with their unique structural characteristics, exhibit high extraction capabilities for actinide ions of different valence states, while showing extremely low extraction capabilities for rare earth elements. This selective extraction mechanism enables asymmetric ligands to efficiently separate actinide ions from mixtures containing lanthanides, achieving excellent lanthanum-actinium separation. This characteristic not only improves separation efficiency but also reduces separation costs, making it of significant practical application value in fields such as nuclear fuel reprocessing and radioactive waste treatment. Furthermore, the two nitrogen atoms of 1,10-phenanthroline exhibit excellent coordination ability with transition metals. Studies have shown that introducing electron-donating atoms at the 2 and 9 positions significantly enhances the overall coordination ability of the ligand through synergistic effects with the nitrogen atoms. This modification strategy provides a new approach for developing high-performance asymmetric phenanthroline ligands.

[0004] Currently, the synthesis of asymmetric 1,10-phenanthroline mostly uses commercially available 2,9-dimethyl-1,10-phenanthroline as the starting material, employing two main control strategies. One strategy involves oxidizing the methyl group to an aldehyde group using selenium dioxide, followed by stepwise reactions to further connect different groups; the other involves further oxidizing the aldehyde group to a carboxyl group, and then activating the carboxyl group to connect different end groups. While these synthetic methods can yield asymmetric phenanthroline with different substituents, the synthetic process typically involves multiple intermediate steps, as well as possible protection and deprotection steps. This not only prolongs the synthesis cycle and reduces production efficiency, but also limits the types of functionalizable asymmetric phenanthroline ligands due to the limited reaction types of the aldehyde and carboxyl groups. Ultimately, this severely restricts the research on the diversity of asymmetric 1,10-phenanthroline ligands and their application prospects in large-scale production. Summary of the Invention

[0005] In view of this, the purpose of this invention is to overcome the problems of long synthetic routes, low synthetic efficiency and limited substrate expansion of asymmetric 1,10-phenanthroline in the prior art, and to provide a synthetic method and application of asymmetric 1,10-phenanthroline.

[0006] In a first aspect, the present invention provides a method for synthesizing asymmetric 1,10-o-phenanthroline, comprising the following steps: S1, 8-aminoquinoline and crotonaldehyde react under acidic conditions with NaI catalysis to obtain intermediate 1; S2, intermediate 1 undergoes an oxidation reaction under acidic conditions to obtain intermediate 2; S3, intermediate 2 reacts with phosphorus trihalomethane to obtain the asymmetric 1,10-o-phenanthroline; wherein the phosphorus trihalomethane includes at least one of phosphorus oxychloride and phosphorus tribromide.

[0007] In some optional embodiments, the synthetic route for the asymmetric 1,10-phenanthroline is shown below: .

[0008] In some optional embodiments, S1 includes the following steps: after mixing 8-aminoquinoline and NaI, an inorganic acid and crotonaldehyde are added sequentially, followed by reaction, quenching, pH adjustment, extraction, and column chromatography to obtain intermediate 1.

[0009] In some alternative implementations, in S1, the inorganic acid is added dropwise.

[0010] In some optional embodiments, in S1, the pH is adjusted with an alkali agent to a pH of 7-8; the alkali agent includes at least one of sodium carbonate, potassium carbonate, and sodium bicarbonate.

[0011] In some optional embodiments, in S1, the molar ratio of the added 8-aminoquinoline, crotonaldehyde, and NaI is 10:(20-30):(0.1-0.15).

[0012] In some alternative embodiments, in S1, the concentration of the 8-aminoquinoline in the inorganic acid is 2.5 mol / L to 3 mol / L.

[0013] In some optional embodiments, in S1, the inorganic acid is aqueous concentrated sulfuric acid; the concentration of the aqueous concentrated sulfuric acid is 65%-85%.

[0014] In some optional embodiments, in S1, the reaction temperature is 100℃-120℃; the reaction time is 1.5h-2.5h.

[0015] In some alternative embodiments, in S1, the solvent for extraction is at least one of dichloromethane or chloroform.

[0016] In some alternative implementations, in S1, the quenching solution is water.

[0017] In some optional embodiments, in S1, the eluent for the column chromatography is dichloromethane:methanol = (20-30):1.

[0018] In some alternative embodiments, S2 includes the following steps: intermediate 1 is dispersed in an organic acid, an oxidant is added, and intermediate 2 is obtained by reaction, quenching, pH adjustment, extraction, drying, and concentration.

[0019] In some alternative embodiments, in S2, the quenching solvent is water.

[0020] In some optional embodiments, in S2, the pH is adjusted with an alkali agent to a pH of 7-8; the alkali agent includes at least one of sodium carbonate, potassium carbonate, and sodium bicarbonate.

[0021] In some alternative embodiments, in S2, the molar ratio of intermediate 1 to hydrogen peroxide added is 1:(1-10). In some alternative embodiments, in S2, the concentration of intermediate 1 in the organic acid is 0.5 mol / L to 1.0 mol / L.

[0022] In some alternative embodiments, in S2, the solvent for extraction is at least one of dichloromethane or chloroform.

[0023] In some alternative embodiments, in S2, the organic acid is selected from at least one of acetic acid and trifluoroacetic acid.

[0024] In some alternative embodiments, in S2, the oxidant includes at least one of hydrogen peroxide, ozone, and peracetic acid.

[0025] In some optional embodiments, in S2, the temperature of the oxidation reaction is 65°C-80°C; and the time of the oxidation reaction is 3h-5h.

[0026] In some alternative embodiments, S3 includes the following steps: intermediate 2 is mixed with a solvent, phosphorus trihalomethane and N,N-dimethylformamide are added in a protective atmosphere, and the mixture is reacted, quenched, pH adjusted, extracted, and column chromatography is performed to obtain the asymmetric 1,10-o-phenanthroline.

[0027] In some optional embodiments, in S3, the pH is adjusted with an alkali agent to a pH of 7-8; the alkali agent includes at least one of sodium carbonate, potassium carbonate, and sodium bicarbonate.

[0028] In some alternative embodiments, in S3, the quenching solvent is water.

[0029] In some alternative embodiments, in S3, the solvent for extraction is at least one of dichloromethane or chloroform.

[0030] In some alternative embodiments, in S3, the solvent includes at least one of dichloromethane, tetrahydrofuran, and acetonitrile.

[0031] In some alternative embodiments, in S3, the protective atmosphere includes at least one of nitrogen, argon, and helium.

[0032] In some optional embodiments, in S3, the addition temperature of the trihalomethane and N,N-dimethylformamide is -5°C to 5°C.

[0033] In some optional embodiments, S3, the reaction temperature is 20°C-40°C; the reaction time is 8h-16h.

[0034] In some optional embodiments, in S3, the molar ratio of intermediate 2, phosphorus trihalomethane, and N,N-dimethylformamide is 1:(1.0-2.0):(0.5-1.5).

[0035] In some alternative embodiments, in S3, the concentration of intermediate 2 in the solvent is 0.05 mol / L to 0.4 mol / L.

[0036] In some optional embodiments, in S3, the eluent for the column chromatography is dichloromethane:methanol = (50-70):1.

[0037] Secondly, the present invention also provides an application of asymmetric 1,10-phenanthroline prepared by the synthetic method of asymmetric 1,10-phenanthroline described in the first aspect in lanthanide luminescent complexes, transition metal-catalyzed organic reactions, rare earth element separation, and lanthanum-actinium separation.

[0038] The technical solution of the present invention has the following advantages: 1. The method for synthesizing asymmetric 1,10-phenanthroline provided by this invention includes the following steps: S1, 8-aminoquinoline and crotonaldehyde react under acidic conditions with NaI catalysis to obtain intermediate 1; S2, intermediate 1 undergoes an oxidation reaction under acidic conditions to obtain intermediate 2; S3, intermediate 2 reacts with phosphorus trihalomethane to obtain the asymmetric 1,10-phenanthroline; wherein the phosphorus trihalomethane includes at least one of phosphorus oxychloride and phosphorus tribromide. The method for synthesizing asymmetric 1,10-phenanthroline of this invention utilizes three efficient reaction steps, has a short synthesis cycle, high production efficiency, and uses readily available and inexpensive raw materials. It not only provides researchers with a convenient and efficient synthesis method but is also suitable for large-scale industrial production, meeting the market demand for phenanthroline derivatives.

[0039] 2. The core of the asymmetric synthesis method for 1,10-phenanthroline provided by this invention lies in the selective oxidation in step S2. Specifically, the presence of the methyl group allows the reaction to selectively occur on the N-terminus on the other side, thereby generating the final brominated product in the bromination reaction in step S3. Attached Figure Description

[0040] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0041] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of intermediate 1-1 in Example 1 of the present invention; Figure 2 This is the 1H NMR spectrum of compound N-1 from Example 1 of this invention; Figure 3 This is the carbon NMR spectrum of compound N-1 in Example 1 of this invention; Figure 4 This is the high-resolution mass spectrum of compound N-1 from Example 1 of this invention; Figure 5 This is a single-crystal structure diagram of compound N-1 from Example 1 of the present invention; Figure 6This is the 1H NMR spectrum of compound N-2 from Example 6 of this invention. Detailed Implementation

[0042] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0043] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0044] When it comes to material ratios, it refers to volume ratios.

[0045] Example 1: Synthesis of compound N-1

[0046] Synthesis of Intermediate 1-1: 17 mL of 75% sulfuric acid was slowly added to 8-aminoquinoline (50 mmol) and NaI (0.5 mmol). The mixture was heated to 110 °C, followed by slow dropwise addition of crotonaldehyde (120 mmol). The mixture was reacted at 110 °C for 2 hours, cooled to room temperature, quenched with water, and the pH was adjusted to 7 with saturated sodium carbonate solution. Extraction was performed with dichloromethane, and the organic phase was dried over anhydrous magnesium sulfate. The organic solvent was removed by vacuum distillation. The crude product was separated by column chromatography (dichloromethane:methanol = 30:1) to obtain a black oily liquid, namely Intermediate 1-1 (yield 61.8%). [Further details regarding the synthesis of Intermediate 1-1 are needed for accurate translation.] 1 The 1H NMR spectrum of intermediate 1-1 was obtained by 1H NMR testing. Figure 1 As shown. 1 H NMR (600 MHz, Chloroform-d) δ 9.20 (dd, J = 4.3,1.8 Hz, 1H), 8.23 ​​(dd, J = 8.1, 1.8 Hz, 1H), 8.13 (d, J = 8.2 Hz, 1H), 7.79 –7.70 (m, 2H), 7.60 (dd, J = 8.0, 4.3 Hz, 1H), 7.51 (d, J = 8.2 Hz, 1H), 2.95 (s, 3H).

[0047] Synthesis of intermediate 2-1: Intermediate 1-1 (31 mmol) was dissolved in 40 mL of acetic acid. Hydrogen peroxide (4 mL, 30%) was added and the mixture was reacted at 70 °C for 2 hours. Hydrogen peroxide (4 mL, 30%) was added again and the mixture was reacted for 1 hour. Finally, hydrogen peroxide (3 mL, 30%) was added and the mixture was reacted for 1 hour. The mixture was cooled to room temperature, quenched with water, and the pH was adjusted to 7 with a saturated sodium carbonate aqueous solution. The mixture was extracted with dichloromethane, and the organic phase was dried over anhydrous magnesium sulfate. The organic solvent was removed by vacuum distillation to obtain a yellow solid, namely intermediate 2-1 (yield 58%).

[0048] Synthesis of compound N-1: Intermediate 2-1 (18 mmol) was dissolved in 80 mL of dry dichloromethane. Under N2 protection, phosphorus tribromooxyphosphate (27.1 mmol) and DMF (15.4 mmol) were added at 0 °C. The reaction was carried out at room temperature for 12 h. The reaction was quenched with water, and the pH was adjusted to 7 with saturated sodium carbonate aqueous solution. The mixture was extracted with dichloromethane, and the organic phase was dried over anhydrous magnesium sulfate. The organic solvent was removed by vacuum distillation. The crude product was separated by column chromatography (dichloromethane:methanol = 60:1) to obtain pale yellow crystals, namely compound N-1 (yield 40.8%).

[0049] For compound N-1 1 H NMR, 13 The NMR spectrum of compound N-1 was measured using 1H NMR, high-resolution mass spectrometry (HRMS), and single-crystal structure analysis. Figure 2 As shown, the 1H NMR spectrum of compound N-1 is as follows: Figure 3 As shown, the high-resolution mass spectrum of compound N-1 is as follows: Figure 4 As shown, the single-crystal structure of compound N-1 is as follows. Figure 5 As shown. 1 H NMR (600 MHz, Chloroform-d) δ 8.14 (d, J = 8.2 Hz, 1H), 8.07 (d, J = 8.3 Hz, 1H), 7.81 (d,J = 8.7 Hz, 1H), 7.75 (d, J = 8.3 Hz, 1H), 7.72 (d, J = 8.7 Hz, 1H), 7.53 (d,J = 8.2 Hz, 1H), 2.94 (s, 3H); 13C NMR (150 MHz, Chloroform-d) δ 160.10, 146.30, 144.32, 142.40, 138.24, 136.34, 127.72, 127.64, 127.06, 127.05, 124.88, 124.28, 25.76; where chemical shifts (δ) are reported in ppm. HRMS m / z: [C 13 H9BrN2Na + ] + ([M+Na)) + Theoretical value: 294.98426, Measured value: 294.9842.

[0050] Example 2: Synthesis of compound N-1 Synthesis of intermediate 1-1: The synthesis of intermediate 1-1 in this example is the same as that in Example 1, except that the amount of crotonaldehyde added is 100 mmol, and intermediate 1-1 is obtained (yield 55%).

[0051] Synthesis of intermediate 2-1: The synthesis of intermediate 1-1 in this example is the same as that in Example 1, except that the volumes of hydrogen peroxide added three times are 5 mL, 5 mL and 3 mL respectively, to obtain intermediate 2-1 (yield 65%).

[0052] Synthesis of compound N-1: The synthesis of compound N-1 in this example is the same as that of compound N-1 in Example 1, except that the amount of phosphorus tribromooxyphosphorus added is 18 mmol, and compound N-1 is obtained (yield 10%).

[0053] Example 3: Synthesis of compound N-1 Synthesis of intermediate 1-1: The synthesis of intermediate 1-1 in this example is the same as that in Example 1, except that the amount of crotonaldehyde added is 150 mmol, and intermediate 1-1 is obtained (yield 70%).

[0054] Synthesis of intermediate 2-1: The synthesis of intermediate 1-1 in this example is the same as that in Example 1, except that the volumes of hydrogen peroxide added three times are 3 mL, 3 mL and 2 mL respectively, to obtain intermediate 2-1 (yield 50%).

[0055] Synthesis of compound N-1: The synthesis of compound N-1 in this example is the same as that of compound N-1 in Example 1, except that the amount of phosphorus tribromooxyphosphine added is 36 mmol, and compound N-1 is obtained (yield 40%).

[0056] Example 4: Synthesis of compound N-1 Synthesis of intermediate 1-1: The synthesis of intermediate 1-1 in this embodiment is the same as that in Example 1, except that 75% sulfuric acid is replaced with 65% sulfuric acid to obtain intermediate 1-1 (yield 56%).

[0057] Synthesis of intermediate 2-1: The synthesis of intermediate 1-1 in this example is the same as that in Example 1, except that acetic acid is replaced with trifluoroacetic acid to obtain intermediate 2-1 (yield 52%).

[0058] Synthesis of compound N-1: The synthesis of compound N-1 in this example is the same as that of compound N-1 in Example 1, except that dry dichloromethane is replaced with dry tetrahydrofuran to obtain compound N-1 (yield 38%).

[0059] Example 5: Synthesis of compound N-1 Synthesis of intermediate 1-1: The synthesis of intermediate 1-1 in this embodiment is the same as that in Example 1, except that the reaction temperature is 100°C, and intermediate 1-1 is obtained (yield 60%).

[0060] Synthesis of intermediate 2-1: The synthesis of intermediate 1-1 in this embodiment is the same as that in Example 1, except that the reaction temperature is 80°C, and intermediate 2-1 is obtained (yield 45%).

[0061] Synthesis of compound N-1: The synthesis of compound N-1 in this embodiment is the same as that of compound N-1 in Example 1, except that the reaction time is 16 h, and compound N-1 is obtained (yield 40%).

[0062] Example 6: Synthesis of compound N-2

[0063] Synthesis of compound N-2: The synthesis of compound N-2 is the same as that of compound N-1 in Example 1, except that phosphorus tribromooxyphosphorus is replaced with phosphorus trichloride to obtain compound N-2 (yield 40%).

[0064] For compound N-2 1 H NMR and 13 The 1H NMR spectrum of compound N-2 was obtained by 1C NMR testing, as shown below. Figure 6 As shown. 1¹H NMR (600 MHz, Chloroform-d) δ 8.19 (d, J = 8.4 Hz, 1H), 8.15 (d, J = 8.2 Hz, 1H), 7.80 (d, J = 8.7 Hz, 1H), 7.77 – 7.71 (m, 1H), 7.61 (d, J = 8.3 Hz, 1H), 7.54 (d, J = 8.2 Hz, 1H), 2.95 (s, 3H), where chemical shifts (δ) are reported in ppm.

[0065] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for synthesizing asymmetric 1,10-phenanthroline, characterized in that, Includes the following steps: S1, 8-aminoquinoline and crotonaldehyde react under acidic conditions with NaI catalysis to give intermediate 1; S2 and intermediate 1 are oxidized under acidic conditions to obtain intermediate 2; S3 and intermediate 2 react with phosphorus trihalooxy to obtain the asymmetric 1,10-o-phenanthroline; The phosphorus trihalomethane includes at least one of phosphorus oxychloride and phosphorus tribromooxychloride.

2. The method for synthesizing asymmetric 1,10-phenanthroline according to claim 1, characterized in that, S1 includes the following steps: After mixing 8-aminoquinoline and NaI, inorganic acid and crotonaldehyde were added sequentially. The mixture was reacted, quenched, pH adjusted, extracted, and subjected to column chromatography to obtain intermediate 1. Preferably, in S1, the inorganic acid is added dropwise; Preferably, in S1, the pH is adjusted with an alkaline agent, and the adjusted pH is 7-8; Preferably, the alkaline agent includes at least one of sodium carbonate, potassium carbonate, and sodium bicarbonate.

3. The method for synthesizing asymmetric 1,10-phenanthroline according to claim 1 or 2, characterized in that, In S1, the molar ratio of 8-aminoquinoline, crotonaldehyde, and NaI is 10:(20-30):(0.1-0.15). Preferably, in S1, the concentration of 8-aminoquinoline in the inorganic acid is 2.5 mol / L-3 mol / L; Preferably, in S1, the inorganic acid is aqueous concentrated sulfuric acid; Preferably, the concentration of the aqueous concentrated sulfuric acid is 65%-85%; Preferably, in step S1, the reaction temperature is 100℃-120℃; the reaction time is 1.5h-2.5h. Preferably, in S1, the solvent for extraction is at least one of dichloromethane or chloroform; Preferably, in S1, the quenching solution is water; Preferably, in S1, the eluent for column chromatography is dichloromethane:methanol = (20-30):

1.

4. The method for synthesizing asymmetric 1,10-phenanthroline according to any one of claims 1-3, characterized in that, S2 includes the following steps: intermediate 1 is dispersed in an organic acid, an oxidant is added, and intermediate 2 is obtained by reaction, quenching, pH adjustment, extraction, drying and concentration. Preferably, in S2, the quenching solvent is water; Preferably, in step S2, the pH is adjusted using an alkaline agent, and the adjusted pH is 7-8; Preferably, the alkaline agent includes at least one of sodium carbonate, potassium carbonate, and sodium bicarbonate.

5. The method for synthesizing asymmetric 1,10-phenanthroline according to any one of claims 1-4, characterized in that, In S2, the molar ratio of intermediate 1 to hydrogen peroxide is 1:(1-10). Preferably, in S2, the concentration of intermediate 1 in the organic acid is 0.5 mol / L-1.0 mol / L; Preferably, in step S2, the solvent for extraction is at least one of dichloromethane or chloroform; Preferably, in S2, the organic acid is selected from at least one of acetic acid and trifluoroacetic acid; Preferably, in S2, the oxidant includes at least one of hydrogen peroxide, ozone, and peracetic acid; Preferably, in S2, the temperature of the oxidation reaction is 65℃-80℃; and the time of the oxidation reaction is 3h-5h.

6. The method for synthesizing asymmetric 1,10-phenanthroline according to any one of claims 1-5, characterized in that, S3 includes the following steps: Intermediate 2 was mixed with a solvent, and phosphorus trihalomethane and N,N-dimethylformamide were added under a protective atmosphere. The mixture was then reacted, quenched, pH adjusted, extracted, and subjected to column chromatography to obtain the asymmetric 1,10-o-phenanthroline. Preferably, in step S3, the pH is adjusted using an alkaline agent, and the adjusted pH is 7-8; Preferably, the alkaline agent includes at least one of sodium carbonate, potassium carbonate, and sodium bicarbonate; Preferably, in S3, the quenching solvent is water.

7. The method for synthesizing asymmetric 1,10-phenanthroline according to any one of claims 1-6, characterized in that, In S3, the solvent for extraction is at least one of dichloromethane or chloroform; Preferably, in S3, the solvent includes at least one of dichloromethane, tetrahydrofuran, and acetonitrile; Preferably, in S3, the protective atmosphere includes at least one of nitrogen, argon, and helium.

8. The method for synthesizing asymmetric 1,10-phenanthroline according to any one of claims 1-7, characterized in that, In S3, the addition temperature of the trihalomethane and N,N-dimethylformamide is -5℃ to 5℃; Preferably, in step S3, the reaction temperature is 20℃-40℃, and the reaction time is 8h-16h.

9. The method for synthesizing asymmetric 1,10-phenanthroline according to any one of claims 1-8, characterized in that, In S3, the molar ratio of intermediate 2, phosphorus trihalomethane, and N,N-dimethylformamide is 1:(1.0-2.0):(0.5-1.5). Preferably, in step S3, the concentration of intermediate 2 in the solvent is 0.05 mol / L to 0.4 mol / L. Preferably, in S3, the eluent for column chromatography is dichloromethane:methanol = (50-70):

1.

10. The application of asymmetric 1,10-phenanthroline prepared by the synthetic method of any one of claims 1-9 in lanthanide luminescent complexes, transition metal-catalyzed organic reactions, rare earth element separation, and lanthanum-actinium separation.

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