Method for separating metallofullerene M@C.SUB.82 .and isomers thereof

Abstract

A method for separating a metallofullerene M@C.sub.82, comprises steps of: a) adding a Lewis acid to an extract containing the metallofullerene M@C.sub.82 to react therewith, producing a complex precipitate; b) washing the precipitate, followed by dissolving and filtering to obtain a purified metallofullerene M@C.sub.82 extract, wherein M is one or more selected from the group consisting of lanthanide metals Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, and Lu; and the Lewis acid is one or more selected from the group consisting of zinc chloride, nickel chloride, copper chloride, zinc bromide, nickel bromide, and copper bromide.

Claims

1. A method for separating a metallofullerene M@C.sub.82, comprising the following steps: a) complexing precipitation of the metallofullerene M@C.sub.82 with a Lewis acid, which comprises: adding a Lewis acid to an organic solvent extract containing the metallofullerene M@C.sub.82 to react therewith, followed by filtering, and collecting the resulting precipitate and filtrate, wherein the precipitate is a complex of the metallofullerene M@C.sub.82 and the Lewis acid, and the filtrate contains hollow fullerenes; and b) extraction of the metallofullerene M@C.sub.82, which comprises: washing the precipitate with water or an alkaline solution to remove the residual Lewis acid, then adding an organic solvent to fully dissolve the precipitate, followed by filtering, thereby obtaining a filtrate, which is a purified organic solvent extract of the metallofullerene M@C.sub.82; wherein M is one or more selected from the group consisting of lanthanide metals Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, and Lu; and the Lewis acid is copper bromide.

2. The method according to claim 1, wherein M is the lanthanide metal Gd.

3. The method according to claim 1, wherein the organic solvent extract in the step (a) is one or more selected from the group consisting of benzene extract, chlorobenzene extract, toluene extract, o-xylene extract, m-xylene extract, para-xylene extract, carbon disulfide extract, and N,N-dimethylformamide extract.

4. The method according to claim 1, wherein reaction conditions in the step (a) are a stirred reaction, and reaction time is 1-24 hours.

5. The method according to claim 1, wherein reaction conditions in the step (a) are an ultrasonic reaction, and reaction time is 1-8 hours.

6. The method according to claim 1, wherein said collecting the precipitate and filtrate in the step (a) is by filtering or by centrifuging.

7. The method according to claim 1, wherein the alkaline solution in the step (b) is one or more selected from the group consisting of aqueous solutions of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, lithium hydroxide, lithium carbonate and lithium bicarbonate.

8. The method according to claim 1, wherein the organic solvent in the step (b) is one or more selected from a phenyl solvent or carbon disulfide.

9. The method according to claim 1, wherein the filtrate obtained in the step (b) contains two isomers: M@C.sub.2v-C.sub.82 and M@C.sub.s-C.sub.82.

10. The method according to claim 9, further comprising steps of separating the two isomers: I) adding a Lewis acid to the purified organic solvent extract of the metallofullerene M@C.sub.82 for a stirred reaction or an ultrasonic reaction, followed by filtering, and collecting a precipitate and filtrate 1, wherein the precipitate is a complex of the Lewis acid and M@C.sub.s-C.sub.82, and the filtrate 1 is an organic solution containing only M@C.sub.2v-C.sub.82; and II) washing the precipitate with an alkaline solution to remove the residual Lewis acid, and then adding an organic solvent to fully dissolve the precipitate, followed by filtering, thereby obtaining filtrate 2, which is an organic solution containing only M@C.sub.s-C.sub.82, wherein the reaction in the step (I) lasts for 20-60 minutes.

11. The method according to claim 10, wherein the alkaline solution in the step (II) is one or more selected from the group consisting of aqueous solutions of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

12. The method according to claim 10, wherein the organic solvent in the step (II) is one or more selected from a phenyl solvent or carbon disulfide.

13. The method according to claim 10, wherein the Lewis acid in the step (I) is one or more selected from the group consisting of zinc chloride, nickel chloride, copper chloride, zinc bromide, nickel bromide, and copper bromide.

14. The method according to claim 10, wherein in the step (I), when M is selected from the lanthanide metal Gd, the Lewis acid is copper chloride or copper bromide.

15. The method according to claim 1, wherein the organic solvent extract in the step (a) is toluene extract.

16. The method according to claim 1, wherein reaction conditions in the step (a) are a stirred reaction, and reaction time is 1-8 hours.

17. The method according to claim 1, wherein reaction conditions in the step (a) are an ultrasonic reaction, and reaction time is 1-3 hours.

18. The method according to claim 1, wherein the organic solvent in the step (b) is one or more selected from toluene, o-xylene, p-xylene, m-xylene, or carbon disulfide.

19. The method according to claim 10, wherein the organic solvent in the step (II) is one or more selected from toluene, o-xylene, p-xylene, m-xylene, or carbon disulfide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a high-performance liquid chromatogram before separation of Gd@C.sub.82 extract with copper bromide;

(2) FIG. 2 is a high-performance liquid chromatogram of a product obtained after separating Gd@C.sub.82 extract for 3 hours with copper bromide;

(3) FIG. 3 is a high-performance liquid chromatogram of a solution obtained after separating Gd@C.sub.82 extract for 3 hours with copper bromide;

(4) FIG. 4 is an MALDI-TOF mass spectrum of Gd@C.sub.82 separated and purified with copper bromide;

(5) FIG. 5 is a high-performance liquid chromatogram of a product obtained after separating Gd@C.sub.82 extract for 3 hours with copper chloride;

(6) FIG. 6 is a high-performance liquid chromatogram of a product obtained after separating Gd@C.sub.82 extract for 8 hours with copper chloride.

(7) FIG. 7 is a high-performance liquid chromatogram of a solution obtained after separating Gd@C.sub.82 extract for 8 hours with copper chloride.

(8) FIG. 8 is a high-performance liquid chromatogram of a product obtained after separating Gd@C.sub.82 extract for 3 hours with zinc bromide.

(9) FIG. 9 is a high-performance liquid chromatogram of a product obtained after separating Gd@C.sub.82 extract for 8 hours with zinc bromide.

(10) FIG. 10 is a high-performance liquid chromatogram of a solution obtained after separating Gd@C.sub.82 extract for 8 hours with zinc bromide.

(11) FIG. 11 is a high-performance liquid chromatogram of a product obtained after separating Gd@C.sub.82 isomer solution for 20 minutes with copper bromide.

(12) FIG. 12 is a high-performance liquid chromatogram of a solution obtained after separating Gd@C.sub.82 isomer solution for 20 minutes with copper bromide.

(13) FIG. 13 is a high-performance liquid chromatogram of a product after separating Gd@C.sub.82 isomer solution for 40 minutes with copper bromide.

(14) FIG. 14 is a high-performance liquid chromatogram of a solution after separating Gd@C.sub.82 isomer solution for 40 minutes with copper bromide.

(15) FIG. 15 is a high-performance liquid chromatogram of a product after separating Gd@C.sub.82 isomer solution for 60 minutes with copper bromide.

(16) FIG. 16 is a high-performance liquid chromatogram of a solution after separating Gd@C.sub.82 isomer solution for 60 minutes with copper bromide.

(17) FIG. 17 is an ultraviolet—visible—near infrared spectrum of two isomers (Gd@C.sub.2v-C.sub.82 and Gd@C.sub.s-C.sub.82) obtained after separation of Gd@C.sub.82 isomer solution with copper bromide.

DETAILED DESCRIPTION OF THE INVENTION

(18) In order to explain the objects, technical solutions and advantages of the examples of the present disclosure more clearly, the technical solutions in the examples of the present disclosure will be illustrated clearly and completely in combination with one or more examples and corresponding drawings.

(19) It is apparent that the described examples are part of examples of the present disclosure rather than all examples. Based on the examples of the present disclosure, all other examples obtained by a person of ordinary skill in the art without creative work shall fall within the protection scope of the present disclosure. Unless explicitly stated otherwise, the term “comprise” or variations thereof such as “comprising” throughout the description and claims will be construed to comprise the stated components, rather than exclude other elements or other components.

(20) These examples do not limit the scope of protection. Unless otherwise stated, any example herein is not necessarily to be construed as superior to or better than the other examples.

(21) In addition, in order to better illustrate the present disclosure, numerous specific details will be given in the following examples. Those skilled in the art should understand that the present disclosure can be implemented without some specific details. In some examples, the methods, means and elements that are well known to those skilled in the art, and experimental methods that are typically in accordance with conventional conditions and the conditions described in the manual or in accordance with the conditions recommended by the manufacturer are not described in detail in order to highlight the subject matter of the present disclosure. The materials, reagents and the like used herein are conventionally commercially available unless otherwise specified.

Example 1

Separation and Extraction of Metallofullerene Gd@C.SUB.82

(22) (1) Separation of Metallofullerene Gd@C.sub.82 by Copper Bromide (CuBr.sub.2)

(23) (a) Metal Gd powder and spectrography graphite powder were mixed and then put into a hollow graphite tube and compacted, and soot containing a fullerene product was obtained by the electric arc-discharge method. The soot was put into a filter paper bag and placed into a soxhlet extractor for extraction with N,N-dimethylformamide (DMF) as the solvent under the conditions of 150° C. and low vacuum for 24 hours to obtain a black solution.

(24) (b) The above solution was filtered to remove a large amount of suspended particles, and 500 mL of the filtrate was put into a round bottom flask, and completely evaporated using a rotary evaporator. To the above round bottom flask, 500 mL of toluene was added, and then the round bottom flask was placed into an ultrasonic reactor (model: KQ-300 DB; power: 300 W; and ultrasonic frequency: 40 KHz) for an ultrasonic reaction for 2 hours; and a clear brown-yellow filtrate, namely, a toluene extract containing the hollow fullerenes and the metallofullerenes, was obtained by filtering. The above filtrate was analyzed by high-performance liquid chromatography (HPLC), as shown in FIG. 1.

(25) (c) To the above toluene extract, 50 mg of CuBr.sub.2 was added for a stirred reaction at 1000 rpm for 3 hours. During the reaction, a large amount of brown powdery precipitate was produced. The precipitate was collected after filtering using a solvent filter, and the filtrate did not contain the metallofullerene, but contained only the hollow fullerenes. The high-performance liquid chromatography (HPLC) is shown in FIG. 3.

(26) (d) The precipitate was washed three times with an aqueous solution of sodium carbonate in the solvent filter; the residual water was removed completely by suction filtration; the washed precipitate was put into a 1000 mL triangular flask and 500 mL of toluene was added thereto, and then the triangular flask was put into the ultrasonic reactor to react for 30 minutes so that the purified metallofullerene was fully dissolved in the toluene; and a bright yellow filtrate was collected after filtering using the solvent filter.

(27) (e) The filtrate obtained in step (d) was characterized by high-performance liquid chromatography (HPLC) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), as shown in FIG. 2 and FIG. 4. HPLC was carried out under the conditions of toluene as the mobile phase, a flow rate 1 mL/min, sample injection 20 μL, a UV monitoring wavelength 300 nm, and a PYE column (5 μm, 4.6×250 mm, Cosmosil) as the chromatographic column, and each chromatographic peak was subject to automatic integration. The test results of HPLC and MALDI-TOF-MS proved that the purity of the isolated metallofullerene Gd@C.sub.82 was more than 99% and the separation yield could be more than 90% (the separation yield herein is a separation recovery rate, which is calculated by dividing the finally isolated product by the content of the product in the organic solvent extract in step c).

(28) (2) Separation of Metallofullerene Gd@C.sub.82 by other Lewis Acids

(29) In order to further verify the separation effects of the Lewis acids on metallofullerenes, referring to the experimental conditions of Example 1 (1), the Lewis acid were changed correspondingly without changing other parameters and steps, with results as shown in the following table 1:

(30) TABLE-US-00001 TABLE 1 Separation effects of copper chloride and zinc bromide on Gd@C.sub.82 High-Performance Separation Liquid Separation Separation Lewis Acid Time Chromatogram Purity Yield Copper 3 h FIG. 5 97% 17% chloride Copper 8 h FIG. 6 97% 70% chloride Zinc 3 h FIG. 8 98% 10% bromide Zinc 8 h FIG. 9 98% 20% bromide

(31) As can be seen from the table above, other Lewis acids can also effectively separate the metallofullerene Gd@C.sub.82. Compared with the separation of Gd@C.sub.82 by copper bromide for 3 h with the purity of 99% and the separation yield of 90%, the separation by copper chloride was lower in separation rate and separation yield, and the separation time of 8 hours was required to isolate Gd@C.sub.82 with the purity of 97%, of which the separation yield could reach 70%. Zinc bromide could only separate the isomer Gd@C.sub.s-C.sub.82, and could not isolate another isomer Gd@C.sub.2v-C.sub.82, so its separation yield could only reach about 20%.

(32) (3) Influence of Reaction Parameters

(33) In order to determine the influence of parameters such as reaction time on the separation effects in the example of the present disclosure, the parameters of each reaction were changed correspondingly without changing other parameters and steps, with the results as shown in table 3 below:

(34) TABLE-US-00002 TABLE 3 Separation effects of copper bromide on Gd@C.sub.82 under different reaction conditions Concentration of Reactant Gd@C.sub.82 in Toluene Dosage of Reac- Reac- Separa- Separa- Extract Copper tion tion tion tion in Step b) Bromide Condition Time Purity Result ~10 mg/mL  50 mg Stirring 3 h 99% Completely separated ~10 mg/mL 100 mg Stirring 2 h 99% Completely separated ~10 mg/mL  50 mg Ultra- 2 h 99% Completely sound separated ~10 mg/mL 100 mg Ultra- 1 h 99% Completely sound separated

(35) As can be seen from the above table, under different reaction conditions, copper bromide can isolate the metallofullerene Gd@C.sub.82 with the purity of up to 99%. Regardless of stirring operation or ultrasonic operation, increasing the dosage of the Lewis acid can accelerate the reaction rate and shorten the required reaction time.

Example 2

Selective Separation of Gd@C.SUB.82 .Isomers

(36) (1) Separation of Metallofullerene Gd@C.sub.82 Isomers by Copper Bromide (CuBr.sub.2)

(37) (a) The metallofullerene Gd@C.sub.82 prepared by the conventional electric arc-discharge method typically has two isomers with relatively stable chemical properties: Gd@C.sub.2v-C.sub.82 and Gd@C.sub.s-C.sub.82; for example, the bright yellow filtrate isolated in step (d) of Example 1 (1) contained two Gd@C.sub.82 isomers, as shown in FIG. 2. To 500 mL of this solution, 10 mg of CuBr.sub.2 was added, and the stirring (revolving speed: 1000 rpm) time was accurately controlled to be 40 minutes. CuBr.sub.2 reacted preferentially with the isomer Gd@C.sub.s-C.sub.82 to produce a complex precipitate; the precipitate was collected after filtering using a solvent filter, and the filtrate contained only the other isomer Gd@C.sub.2v-C.sub.82.

(38) (b) The precipitate containing only the isomer Gd@C.sub.s-C.sub.82 was washed three times with an aqueous solution of sodium carbonate in the solvent filter; the residual water was removed completely by suction filtration; the washed precipitate was put into a 1000 mL triangular flask and 500 mL of toluene was added thereto, and then ultrasonic treatment was carried out for 30 minutes so that the metallofullerene was fully dissolved; and a bright yellow isomer Gd@C.sub.s-C.sub.82 filtrate was collected after filtering using the solvent filter.

(39) (c) Characterization was carried out by HPLC; under the conditions of toluene as the mobile phase, a flow rate 1 mL/min, sample injection 20 μL, a UV monitoring wavelength 300 nm, a PYE column (5 μm, 4.6×250 mm) as the chromatographic column, the isomers Gd@C.sub.s-C.sub.82 and Gd@C.sub.2v-C.sub.82 isolated in steps (a) and (b) were analyzed, respectively, and each chromatographic peak was subjected to automatic integration, proving that the isomer Gd@C.sub.s-C.sub.82 was isolated in the purity of 98% (FIG. 13) and the isomer Gd@C.sub.2v-C.sub.82 was isolated in the purity of 99% (FIG. 14).

(40) (d) Spectroscopic characterization of the isomers Gd@C.sub.s-C.sub.82 and Gd@C.sub.2v-C.sub.82 isolated in steps (a) and (b) was carried out by using an ultraviolet-visible-near infrared spectrometer, respectively, as shown in FIG. 17; and their absorption spectra were consistent with literature reports, thus proving that high-purity Gd @C.sub.82 isomers can be isolated through chemical reaction kinetic control.

(41) (2) Influence of Reaction Parameters

(42) In order to determine the influence of parameters such as reaction time on the separation effects in the example of the present disclosure, the parameters of each reaction time were changed correspondingly without changing other parameters and steps, with the results as shown in table 4 below:

(43) TABLE-US-00003 TABLE 4 Separation effects of copper bromide on Gd@C.sub.82 isomers under different reaction time Concentration of Reactant Gd@C.sub.82 in Toluene Reac- Reac- Isomer Isomer Extract tion tion Gd@C.sub.s-C.sub.82 Gd@C.sub.2v-C.sub.82 in Step b) Condition Time Purity Purity ~10 mg/mL Stirring 20 min 99% 95% ~10 mg/mL Stirring 40 min 99% 99% ~10 mg/mL Stirring 60 min could not be 99% separated

(44) As can be seen from the above table, when copper bromide was used to separate the isomers of the purified Gd@C.sub.82 (as shown in FIG. 2) in Example 1 (1), high-purity Gd@C.sub.82 isomers could be isolated by strictly controlling the reaction time of the copper bromide and Gd @C.sub.82. After reaction for 20 minutes, only part of the isomer Gd@C.sub.s-C.sub.82 was isolated by the copper bromide (as shown in FIG. 11), and a small amount of isomer Gd@C.sub.s-C.sub.82 (about 5%) and a large amount of isomer Gd@C.sub.2v-C.sub.82 (about 95%) were present in the solution, as shown in FIG. 12. After reaction for 40 minutes, all of the isomer Gd@C.sub.s-C.sub.82 was isolated by the copper bromide (as shown in FIG. 13), and only the isomer Gd@C.sub.2v-C.sub.82 was present in the solution (as shown in FIG. 14). After reaction for 60 minutes, all of the isomer Gd@C.sub.s-C.sub.82 and part of the isomer Gd@C.sub.2v-C.sub.82 were isolated by the copper bromide (as shown in FIG. 15), and only the isomer Gd@C.sub.2v-C.sub.82 was present in the solution (as shown in FIG. 16). Therefore, the reaction time of the copper bromide and Gd@C.sub.82 must be strictly controlled to ensure that all of the isomer Gd@C.sub.s-C.sub.82 was isolated by the copper bromide with only the isomer Gd@C.sub.2v-C.sub.82 remaining in the solution; thus, high-purity Gd@C.sub.82 isomers were isolated through such chemical reaction kinetic control.

(45) Finally, it should be noted that the above examples are only used to illustrate rather than limit the technical solutions of the present disclosure. Although the present disclosure has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that modifications can still be made to the technical solutions described in the foregoing examples, or equivalent replacements can be made to some of the technical features thereof; and these modifications or replacements do not cause the essence of the corresponding technical solution to depart from the spirit and scope of the technical solution in each example of the present disclosure.

INDUSTRIAL APPLICABILITY

(46) A method for separating a metallofullerene M@C.sub.82 and an isomer thereof provided according to the examples of the present disclosure uses a specific Lewis acid to achieve effective, rapid, and highly selective separation with extremely high purity. The method comprises the following steps: a) complexing precipitation of the metallofullerene M@C.sub.82 by a Lewis acid; and b) extraction of the metallofullerene M@C.sub.82. By this method, metallofullerenes can be separated from hollow fullerenes simply and quickly, and high-purity metallofullerene isomers can be further isolated through strict chemical reaction kinetic control. This method is simple to operate, low in cost, high in feasibility, and suitable for large-scale production of metallofullerenes.