JP6757640B2 - Method for Producing Fullerene Derivatives, Compositions and Membranes - Google Patents

Description

The present invention relates to fullerene derivatives, compositions and methods for producing films.

Fullerene compounds are substances that continue to attract attention in the fields of physics and chemistry due to their unique properties. With the establishment of a mass synthesis method for fullerenes by arc discharge in 1990, research on fullerene compounds has become more vigorous and is still the subject of interesting research. Fullerene compounds are already known to be useful materials as semiconductor materials, electronic materials, resin additives, physiologically active substances, etc., and development of various fullerene derivatives suitable for various uses is desired. Among them, it has been shown that carbon films obtained from some fullerene derivatives are effective in materials that require etching resistance, such as resist underlayer films (see, for example, Patent Documents 1 to 4). .. In Patent Documents 1 to 4, a fullerene derivative having high solubility in an organic solvent such as PGMEA is used. After forming a fullerene derivative by a wet method, the substituent of the fullerene derivative is removed by heating. , It has been reported that a carbon film having a high carbon content can be obtained.

However, in Patent Documents 1 to 3, when synthesizing a fullerene derivative, a peroxide is used and a reaction time exceeding 24 hours is required.

Further, in Patent Document 4, since DBU (1,8-Diazabicyclo [5.4.0] undec-7-ene) and iodine used when synthesizing a fullerene derivative are removed, the purification process is complicated and therefore handled. Hateful.

Therefore, the above method is difficult to manufacture on an industrial scale. In addition, depending on the fullerene derivative, a hydroxyl group and a hydroxyphenyl group remain, so that the carbon content is lowered and the etching resistance is insufficient.

Therefore, the functional group which can be produced by a simple method, has high solubility in various organic solvents, has good film forming property, and is added to the fullerene derivative at 500 ° C. Fullerene derivatives that can obtain a carbon film with a high carbon content by desorption at the following temperatures are limited.

Japanese Unexamined Patent Publication No. 2008-20209 International Publication No. 2008/062888 Japanese Unexamined Patent Publication No. 2008-164806 Japanese Unexamined Patent Publication No. 2010-229021

The present invention has been made in view of the above circumstances, can be produced by a simple method, has high solubility in various organic solvents, has good film-forming properties, and has good film-forming properties. An object of the present invention is to provide a fullerene derivative capable of desorbing a functional group added to the fullerene derivative at a temperature of 500 ° C. or lower.

By adding a plurality of nitrile oxides generated in the system to fullerenes, the present inventors have high solubility in various organic solvents, good film-forming properties, and It has been found that a fullerene derivative capable of desorbing a functional group added to a fullerene derivative at a temperature of 500 ° C. or lower can be obtained by a simple method.

That is, the present invention has the following configurations.
[1] The fullerene derivative according to one aspect of the present invention has the general formula (1).

（式中、Ｒ_１は、置換基を有しても良い炭素数１〜２０の炭化水素基、炭素数１〜２０のエステル基または炭素数１〜２０の複素環基であり、ｎは４〜２０であり、ａは１〜１５であり、ＦＬＮは、フラーレン骨格である。）
で表される。
〔２〕上記態様〔１〕に係るフラーレン誘導体において、前記Ｒ_１は、アルキル基またはアルキルオキシカルボニル基である。
〔３〕本発明の一態様に係る組成物は、複数種の上記態様〔１〕または〔２〕に係るフラーレン誘導体を含む。
〔４〕本発明の一態様に係る膜の製造方法は、上記態様〔１〕または〔２〕に係るフラーレン誘導体が有機溶媒に溶解している塗布液を基材へ塗布した後に加熱することにより成膜する。
〔５〕上記態様〔４〕に係る膜の製造方法において、前記有機溶媒が、エステル、エーテルおよび芳香族から選ばれる少なくとも１種である。
〔６〕上記態様〔４〕または〔５〕に係る膜の製造方法において、前記加熱の温度が２００〜５００℃である。

(In the formula, R ₁ is a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, an ester group having 1 to 20 carbon atoms or a heterocyclic group having 1 to 20 carbon atoms, and n is 4 ~ 20, a is 1 to 15, and FLN is a fullerene skeleton.)
It is represented by.
[2] In the fullerene derivative according to the above aspect [1], the R ₁ is an alkyl group or an alkyloxycarbonyl group.
[3] The composition according to one aspect of the present invention contains a plurality of types of fullerene derivatives according to the above-mentioned aspects [1] or [2].
[4] The method for producing a film according to one aspect of the present invention is obtained by applying a coating solution in which the fullerene derivative according to the above aspect [1] or [2] is dissolved in an organic solvent to a substrate and then heating the substrate. Form a film.
[5] In the method for producing a film according to the above aspect [4], the organic solvent is at least one selected from esters, ethers and aromatics.
[6] In the method for producing a film according to the above aspect [4] or [5], the heating temperature is 200 to 500 ° C.

According to the present invention, it can be produced by a simple method, has high solubility in various organic solvents, has good film-forming property, and has functionalities added to the fullerene derivative. A fullerene derivative capable of desorbing a group at a temperature of 500 ° C. or lower can be provided.

This is the result of thermogravimetric measurement of the fullerene derivative (1) of Example 1. It is an infrared absorption spectrum of the fullerene derivative (1) of Example 1. It is an infrared absorption spectrum of the film after the heat treatment of Example 1. This is the result of thermogravimetric measurement of the fullerene derivative (2) of Example 2. It is an infrared absorption spectrum of the fullerene derivative (2) of Example 2. It is an infrared absorption spectrum of the film after the heat treatment of Example 2.

The configuration of the embodiment of the present invention will be described below. The present invention can be carried out by appropriately modifying the gist thereof without changing the gist thereof.

[Fullerene derivative]
The fullerene derivative according to the embodiment of the present invention has the general formula (1).

（式中、Ｒ_１は、置換基を有しても良い炭素数１〜２０の炭化水素基、炭素数１〜２０のエステル基または炭素数１〜２０の複素環基であり、ｎは４〜２０であり、ａは１〜１５であり、ＦＬＮはフラーレン骨格である。）
で表される。

(In the formula, R ₁ is a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, an ester group having 1 to 20 carbon atoms or a heterocyclic group having 1 to 20 carbon atoms, and n is 4 ~ 20, a is 1 to 15, FLN is a fullerene skeleton.)
It is represented by.

In the present specification and claims, the "fullerene derivative" means a compound having a structure in which a specific group is added to the fullerene skeleton, and the "fullerene skeleton" refers to a closed shell structure derived from fullerene. It means the constituent carbon skeleton.

In the embodiment of the present invention, the fullerene is a carbon cluster formed by arranging carbon atoms in a spherical or rugby shape, and the carbon number of the fullerene is usually 60 to 120. Specific examples of fullerenes include C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ , C ₉₀ , C ₉₄ , C ₉₆ and higher orders. The fullerene may be of various kinds, including a mixture of these. For example, the fullerene may be one in which a plurality of fullerenes are bonded via an alkylene chain such as a methylene chain, or one in which the alkylene chain is bonded to carbon atoms at different positions in the fullerene skeleton. Further, the fullerene may further have a substituent other than the oxygen atom and the 2-isoxazoline skeleton, and may be selected from hydrogenated fullerenes, methano-bridged fullerenes, alkyl-substituted fullerenes, aryl-substituted fullerenes and the like, or salts thereof. It may be at least one kind. Of these, C ₆₀ or C ₇₀ is preferable from the viewpoint of easy availability of reaction raw materials during the production of fullerene derivatives. In addition, since the purification cost of C ₆₀ and C ₇₀ can be reduced, fullerenes such as C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ , C ₉₀ , C ₉₄ , C ₉₆ and higher orders are available. It is more preferable to use a mixture containing the above.

[Hydrocarbon group (R ₁ )]
In the general formula (1), R ₁ is a hydrocarbon group having 1 to 20 carbon atoms, an ester group having 1 to 20 carbon atoms, or a heterocyclic group having 1 to 20 carbon atoms, which may have a substituent. .. This R ₁ is bound to the 3-position of the 2-isoxazoline skeleton. When the number of carbon atoms of R ₁ exceeds 20, the reactivity decreases during the synthesis of the fullerene derivative, making it difficult to obtain a sufficient addition number of the 2-isooxazoline skeleton, and forming a membrane containing the fullerene derivative. When the functional group added to the fullerene derivative is desorbed by heating, the desorbed functional group may remain in the system. As will be described later, R ₁ may have a substituent, but when R ₁ has a substituent, the number of carbon atoms of R ₁ including the substituent may be 1 to 20. preferable.

Specific examples of the hydrocarbon group include a linear or branched chain alkyl group such as a methyl group, an ethyl group, a propyl group and an isopropyl group, a cyclic alkyl group such as a cyclopropyl group, a cyclopentyl group and a cyclohexyl group, and a vinyl group. Linear or branched chain alkenyl groups such as propenyl group and hexenyl group, cyclic alkenyl groups such as cyclopentenyl group and cyclohexenyl group, alkynyl group such as ethynyl group and 1-propionyl group, phenyl group, biphenyl group and toluyl group. , Aryl group such as naphthyl group, aralkyl group such as benzyl group and phenethyl group and the like.

Specific examples of the ester group include alkyloxycarbonyl groups such as methoxycarbonyl group, ethoxycarbonyl group, propyloxycarbonyl group, butoxycarbonyl group and hexyloxycarbonyl group, aryloxycarbonyl group such as phenoxycarbonyl group, acetoxy group and propionyl. Examples thereof include an acyloxy group such as an oxy group and a benzoyloxy group.

Specific examples of the heterocyclic group include 2-thienyl group, 2-pyridyl group, furfuryl group and the like.

Of these, an alkyl group or an alkyloxycarbonyl group is preferable because of the availability of raw materials.

Further, the hydrocarbon group constituting R ₁ may have an arbitrary substituent as long as it does not significantly impair the excellent physical properties of the fullerene derivative according to the embodiment of the present invention. At this time, the number of substituents may be one or two or more. When having two or more substituents, one type of substituent may be used, or two or more types may be used in any combination and ratio.

Examples of the substituent include an alkoxy group such as a methoxy group and an ethoxy group, an aryloxy group such as a phenoxy group, a halogen atom such as a tertiary amino group and a fluorine atom, a silyl group such as a trimethylsilyl group and a triethoxysilyl group, and a hydroxy. Examples thereof include an alkylthio group such as a group, a thiol group and a butylthio group, an arylthio group such as a phenylthio group, an acyl group such as an acetyl group, a carbonyloxy group such as an acetoxy group, and an alkyloxycarbonyl group such as an ethoxycarbonyl group.

[Average addition number (n) of 2-isooxazoline skeleton]
In the fullerene derivative according to the embodiment of the present invention, the carbon atoms at the 4- and 5-positions of the 2-isoxazoline skeleton are bonded as two adjacent carbon atoms of the fullerene skeleton. The position where the derivative binds to the fullerene skeleton is not limited and is arbitrary. Further, two or more different 2-isooxazoline skeletons may be bound to the fullerene skeleton.

In the general formula (1), n is the average addition number of 2-isooxazoline skeletons. Specifically, n is 4 or more, preferably 6 or more, from the viewpoint of solubility in an organic solvent. Further, n is 20 or less, preferably 15 or less, from the viewpoint of preserving the original properties of fullerenes.

The average number of 2-isoxazoline skeletons added means the average number of 2-isoxazoline skeletons added to one fullerene skeleton of a fullerene derivative existing in a certain system.

When the fullerene derivative according to the embodiment of the present invention is dissolved in a solvent, the molecular composition formula of the fullerene derivative before the solution or the fullerene derivative from which the solvent is removed from the solution is measured by mass spectrometry and mass spectrometry is performed. The average number of 2-isooxazoline skeletons added can be calculated from the molecular weight derived from data such as analytical method (MS). Further, when the fullerene derivative according to the embodiment of the present invention is formed, the average number of 2-isoxazoline skeletons added can be calculated in the same manner from the scraped fullerene derivative.

[Average addition number of oxygen atoms (a)]
In the fullerene derivative according to the embodiment of the present invention, an oxygen atom is bonded to the fullerene skeleton. Specifically, the oxygen atom is bonded to the fullerene skeleton by bonding the two bonds of the oxygen atom to two adjacent carbon atoms of the fullerene skeleton. That is, the carbon atom of the epoxide forming the three-membered ring is composed of two adjacent carbon atoms of the fullerene skeleton. At this time, the position where the oxygen atom binds to the fullerene skeleton is not limited and is arbitrary.

In the general formula (1), a is the average addition number of oxygen atoms. Specifically, a is 1 or more, preferably 2 or more, from the viewpoint of ease of production. Further, a is 15 or less, preferably 10 or less, more preferably 5 or less, and particularly preferably 3 or less, from the viewpoint of retaining the original properties of fullerene.

Here, the average number of added oxygen atoms means the average number of added oxygen atoms to one fullerene skeleton of a fullerene derivative existing in a certain system.

The average number of added oxygen atoms can be calculated in the same manner as the average number of added 2-isooxazoline skeletons.

[Solubility]
The fullerene derivative according to the embodiment of the present invention is soluble in various organic solvents, and is particularly highly soluble in esters, ethers and aromatics.

In the present specification and claims, "the fullerene derivative is dissolved in an organic solvent" means that the fullerene derivative is mixed with an organic solvent, stirred with a magnetic stirrer for 30 minutes, and then visually precipitated. It means that no substances or insoluble substances are detected. For example, under normal pressure at 25 ° C., a fullerene derivative is added per unit volume (1 mL) of an organic solvent to propylene glycol-1-monomethyl ether-2-acetate (hereinafter, may be appropriately referred to as “PGMEA”). When 100 mg or more is dissolved, it is judged that the fullerene derivative is well soluble in an organic solvent, that is, highly soluble in an organic solvent.

When the fullerene derivative according to the embodiment of the present invention is dissolved in an organic solvent and used, the type of the organic solvent is not limited as long as the fullerene derivative according to the embodiment of the present invention is dissolved.

Examples of organic solvents are ethyl acetate, propyl acetate, butyl acetate, phenyl acetate, methyl propionate, ethyl propionate, propyl propionate, phenyl propionate, methyl 3-methoxypropionate, methyl 3-ethoxypropionate, lactic acid. Linear esters such as methyl and ethyl lactate, esters such as cyclic esters such as γ-butyrolactone and caprolactone, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol-1-monomethyl ether Ether esters such as acetate and propylene glycol-1-monoethyl ether acetate, ketones such as acetone, methyl ethyl ketone, methyl isoamyl ketone, methyl amyl ketone and cyclohexanone, ethers such as tetrahydrofuran, anisole, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, acetonitrile and benzo Examples thereof include nitriles such as nitriles, dimethylsulfoxide, benzene, toluene, xylene, and aromatics such as 1,2,4-trimethylbenzene.

As the organic solvent, only one of them may be used, and two or more kinds may be used in combination in any combination and in any ratio.

Polar organic solvents such as PGMEA and ethyl lactate are organic solvents generally used in the field of semiconductor materials (semiconductor integrated circuits, liquid crystal integrated circuits, liquid crystal screen manufacturing resist materials, etc.). Further, the polar organic solvent is a lower layer having a function of a photoresist suitable for shortening the wavelength of a light source such as KrF excimer laser, ArF excimer laser, EUV (extreme ultraviolet light), and EB (electron beam), and an antireflection film. It is an organic solvent preferably used as a photoresist as a film material. Therefore, the fullerene derivative according to the embodiment of the present invention can be dissolved in the above-mentioned organic solvent widely used in industry.

[Thermal stability]
In the fullerene derivative according to the embodiment of the present invention, the added functional group is eliminated from the fullerene skeleton at a temperature of 200 to 500 ° C. On the other hand, the fullerene skeleton itself has high thermal stability, so that it can exist without decomposition. Therefore, by heating the film containing the fullerene derivative according to the embodiment of the present invention, it is possible to form a film having a high carbon concentration in which the functional groups added to the fullerene derivative are eliminated from the fullerene skeleton. Generally, a film having a high carbon content is known to have excellent etching resistance, and therefore, for example, it can be suitably used as an underlayer film material in a photolithography process.

When evaluating the thermal stability of the fullerene derivative according to the embodiment of the present invention, a heat resistance test at a high temperature may be used, or a thermogravimetric measuring device (TGA) or a differential thermal weight simultaneous measuring device (TGA). TG-DTA) may be used. When evaluating the thermal stability of a fullerene derivative by TG-DTA, the measurement conditions such as the type and amount of gas to be distributed, the type of bread, the rate of temperature rise, the upper limit temperature of measurement, and the amount of sample should be arbitrarily selected. Can be done.

[Manufacturing method of fullerene derivative]
The method for producing the fullerene derivative according to the embodiment of the present invention is not limited and any method can be used, but the fullerene derivative according to the embodiment of the present invention is produced by the production method exemplified below. Is preferable. However, the method for producing a fullerene derivative illustrated below is an example of the method for producing a fullerene derivative according to the embodiment of the present invention, and the method for producing a fullerene derivative according to the embodiment of the present invention is limited to the following examples. It's not a thing.

In the method for producing a fullerene derivative according to the embodiment of the present invention, a target fullerene derivative is obtained by reacting fullerene with a nitrile oxide generated in a reaction system. At this time, it is also possible to use a solvent, and usually, the above reaction is allowed to proceed in the solvent.

The method for generating the nitrile oxide in the reaction system is not particularly limited. For example, nitrile oxides can be generated by using amine-based bases such as triethylamine and diisopropylamine for chloroaldoxime (for example, S. Minakata, S. Okumura, T. Nagamachi, Y. Takeda, Org. Lett. 2011, 13, 2966).

The optimum molar ratio of nitrile oxide to fullerene can be selected depending on the type of nitrile oxide and fullerene, the type of solvent, the concentration of the solvent, the reaction temperature, etc., but is usually preferably 5 to 20. .. When the molar ratio of nitrile oxide to fullerene is 5 or more, the number of nitrile oxides added is improved, the solubility of the fullerene derivative in various organic solvents is high, and when it is 20 or less, the original properties of fullerene are maintained. be able to.

The solvent for dissolving fullerene is not particularly limited as long as it has high solubility, but it should be an aromatic solvent such as benzene, toluene, xylene, 1,2,4-trimethylbenzene, o-dichlorobenzene, anisole and the like. Is preferable. These solvents may be used alone or in combination.

The concentration of the solvent can be used as a guideline for the amount of fullerene dissolved almost completely.

The concentration of fullerene in the solvent is usually preferably 1 to 50 mg / mL. When the concentration of fullerene in the solvent is 1 mg / mL or more, the reaction rate of the reaction between fullerene and nitrile oxide is improved, and when it is 50 mg / mL or less, the raw materials and products are dissolved and the reaction between fullerene and nitrile oxide is carried out. Progresses sufficiently. When two or more kinds of solvents are used in combination, it is desirable that the total amount of the solvents satisfies the above range.

The optimum temperature can be selected depending on the stability of the nitrile oxide used and the reactivity with the fullerene, but it is usually preferably in the range of −10 ° C. to 80 ° C. When the reaction temperature is -10 ° C or higher, the reaction rate of the reaction between fullerene and nitrile oxide is improved, and when the reaction temperature is 80 ° C or lower, the dimerization reaction of nitrile oxide is suppressed and the reaction of nitrile oxide with fullerene is sufficient. Proceed to.

The raw materials for the fullerene derivative used in the method for producing the fullerene derivative according to the embodiment of the present invention are all available at low cost. In addition, the reaction between fullerene and nitrile oxide is completed in a few hours and does not include a column purification step. Therefore, the fullerene derivative according to the embodiment of the present invention can be easily produced using only an inexpensive material.

In such a production method, a composition containing a plurality of fullerene derivatives having different addition positions of the isooxazoline skeleton, oxygen addition positions, and at least one of n and a can be obtained. Further, when a raw material containing a plurality of types of R ₁ or FLN is used, a composition containing a plurality of types of fullerene derivatives having different R ₁ or FLN can be obtained.

A single type of fullerene derivative may be purified from a composition containing a plurality of types of fullerene derivatives, but in the method for producing a film described later, a composition containing a plurality of types of fullerene derivatives may be used as it is.

[Membrane manufacturing method]
In the method for producing a film according to the embodiment of the present invention, a coating liquid in which the fullerene derivative according to the embodiment of the present invention is dissolved in an organic solvent is applied to a substrate and then heated to form a film.

The coating liquid contains the fullerene derivative according to the embodiment of the present invention, but may further contain other components as long as the physical properties of the film are not significantly deteriorated.

In addition, other components may contain only 1 type, and may contain 2 or more types in any combination and arbitrary ratio.

Further, the film according to the embodiment of the present invention may be a single-layer film having the same composition, or may be a multilayer film in which two or more layers having different compositions are laminated.

The film thickness according to the embodiment of the present invention varies greatly depending on the application and cannot be uniformly limited, but is usually 0.01 to 3 μm.

The fullerene derivative according to the embodiment of the present invention is well soluble in various organic solvents.

The organic solvent is not limited, but is preferably at least one selected from an ester solvent, an ether solvent, and an aromatic solvent.

The base material is not limited, and examples thereof include an organic film, a silicon film, and an inorganic film such as a metal wiring.

The method for applying the coating liquid is not limited, and for example, a spray method, a spin coating method, a dip coating method, a roll coating method, or the like can be used.

The heating conditions are not limited, but are usually preferably in the range of 100 to 500 ° C. for 10 to 600 seconds. In particular, when the isooxazoline skeleton is desorbed in order to further increase the carbon content of the membrane, the heating conditions are preferably in the range of 300 to 600 seconds at 200 to 500 ° C.

The heating can be performed in the atmosphere or in an atmosphere of an inert gas such as argon or nitrogen.

The present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

[Example 1]
1,2,4-trimethylbenzene in 4.4 g of fullerene mixture nanom mix-ST (manufactured by Frontier Carbon) containing C ₆₀ , C ₇₀ and other higher-order fullerenes in a ratio of about 60:25:15 (mass ratio). (Hereinafter referred to as "TMB".) (Manufactured by Tokyo Kasei Co., Ltd.) 225 mL was added, and the mixture was stirred at room temperature for 1 hour. After vacuum filtration through the Kiriyama funnel, it was washed with 56 mL of TMB to remove insoluble matter. To this, 17.0 g of ethyl-2-chloro-2- (hydroxyimino) acetate (manufactured by Tokyo Kasei Co., Ltd.) was added, and the mixture was stirred under a nitrogen atmosphere at room temperature for 5 minutes. To this, 16.0 g of diisopropylethylamine (manufactured by Tokyo Kasei Co., Ltd.) was added, and the temperature was raised to 50 ° C. After stirring for 1 hour, 45 mL of anisole (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was further stirred for 1 hour. The reaction solution was filtered under reduced pressure with a Kiriyama funnel, and then washed with 150 mL of ethyl acetate (manufactured by Junsei Chemical Co., Inc.). On the other hand, the solution was separated using 400 mL of ion-exchanged water. The same operation was repeated twice more, and the reaction solution was washed with a total of 1200 mL of water. After the organic layer was concentrated and dried, 200 mL of 2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was filtered under reduced pressure with a Kiriyama funnel. The solid on the Kiriyama funnel was dissolved in ethyl acetate and crystallized with 2-propanol. The crystallized solid is filtered under reduced pressure with a Kiriyama funnel, washed with methanol, and then the obtained brown solid is vacuum dried at 80 ° C. for 15 hours to obtain a chemical formula.

で表されるフラーレン誘導体（１）を８．８ｇ得た。

8.8 g of the fullerene derivative (1) represented by is obtained.

From the above, it can be seen that the fullerene derivative (1) can be produced by a simple method.

[Solubility]
Various organic solvents were added to 0.2 g of the fullerene derivative (1), and the mixture was stirred at 25 ° C. and normal pressure for 30 minutes using a magnetic stirrer to measure the solubility of each.

Table 1 shows the measurement results of the solubility of the fullerene derivative (1).

From Table 1, it can be seen that the fullerene derivative (1) has high solubility in PGMEA, anisole, ethyl lactate, cyclohexanone, and toluene.

[Average addition numbers (n) and (a)]
Elemental analysis of the fullerene derivative (1) gave the following results.

C: 65.27%
H: 2.42%
N: 6.75%
O: 25%
Here, regarding the fullerene skeleton of the fullerene derivative (1), since the fullerene skeleton of C ₇₆ or higher has low reactivity, it is considered that most of the fullerene skeleton of C ₇₆ or higher is removed in the purification step. Therefore, it is presumed that the fullerene skeleton of the fullerene derivative (1) has a C ₆₀ : C ₇₀ ratio of about 70:30 (mass ratio). Considering this point, the obtained composition has an average addition number (n) of 2-isooxazoline skeleton of 9 and an average addition number (a) of oxygen atoms of C ₉₉ H ₄₅ N ₈ O ₂₉ . It showed a value close to the composition. Here, the calculated values of the composition of C ₉₉ H ₄₅ N ₈ O ₂₉ are shown below.

C: 65.17%
H: 2.49%
N: 6.91%
O: 25.43%
[Thermal stability]
The thermal stability of the fullerene derivative (1) was evaluated using a thermogravimetric analyzer (TGA).

FIG. 1 shows the results of thermogravimetric analysis of the fullerene derivative (1).

From FIG. 1, it can be seen that the fullerene derivative (1) loses weight at a temperature of 500 ° C. or lower.

[Infrared absorption spectrum]
The infrared absorption spectrum was measured using a Fourier transform infrared spectrophotometer (FT-IR).

FIG. 2 shows an infrared absorption spectrum of the fullerene derivative (1).

[Film film]
0.4 g of the fullerene derivative (1) was dissolved in 3.6 g of PGMEA (manufactured by ALDRICH) and then filtered through a syringe filter having a filter diameter of 0.2 μm to obtain a PGMEA solution of the fullerene derivative (1). A PGMEA solution of the fullerene derivative (1) was applied to a silicon substrate under the conditions of 1000 rpm and 60 seconds using a spin coater, and then heated and dried at 110 ° C. for 60 seconds to form a film. At this time, since the silicon substrate after the film formation was mirror-shaped, it was confirmed that the fullerene derivative (1) had good film formation properties.

The silicon substrate after the film formation was further heat-treated at 400 ° C. for 300 seconds, and then a part of the film was scraped off to measure the infrared absorption spectrum.

FIG. 3 shows an infrared absorption spectrum of the film after heat treatment.

Comparing FIG. 3 with FIG. 2, it was confirmed that the peak of 2900 to 3000 cm ^-1 derived from the CH expansion and contraction of the alkyl group disappeared, and the isooxazoline skeleton was desorbed from the fullerene skeleton by the heat treatment. Was done.

[Example 2]
270 mL of TMB was added to 17.2 mL of butyl aldoxime (manufactured by Tokyo Kasei Co., Ltd.), and the mixture was stirred at 0 ° C. for 10 minutes under a nitrogen atmosphere. On the other hand, 13.6 mL of tert-butyl hypochlorous acid (manufactured by Tokyo Kasei Co., Ltd.) was added dropwise, and after stirring at 0 ° C. for 2 hours, C ₆₀ , C ₇₀ and other higher-order fullerenes were added at about 60:25. 4.7 g of the fullerene mixture nanom mix-ST (manufactured by Frontier Carbon Co., Ltd.) and 60 mL of TMB containing the fullerene mixture at a ratio of 15 (mass ratio) were added, and the mixture was further stirred at 0 ° C. for 1 hour. 27.3 mL of diisopropylamine (manufactured by Tokyo Kasei Co., Ltd.) was added, and the mixture was further stirred at 0 ° C. for 1 hour. After filtering under reduced pressure with a Kiriyama funnel, the mixture was washed with 150 mL of ethyl acetate to remove insoluble matter. On the other hand, the solution was separated using 300 mL of ion-exchanged water. The same operation was repeated twice more, and the reaction solution was washed with a total of 900 mL of water. The organic layer was concentrated and dried, and then dissolved in a mixed solvent of 2-propanol and acetone (all manufactured by Junsei Chemical Co., Ltd.). After filtering under reduced pressure with a Kiriyama funnel, it was crystallized with a mixed solvent of ion-exchanged water and 2-propanol. After the crystallized solid is filtered under reduced pressure, the obtained brown solid is vacuum dried at 150 ° C. for 15 hours to obtain a chemical formula.

で表されるフラーレン誘導体（２）を９．４ｇ得た。

9.4 g of the fullerene derivative (2) represented by is obtained.

From the above, it can be seen that the fullerene derivative (2) can be produced by a simple method.

[Solubility]
Various solvents were added to 0.2 g of the fullerene derivative (2), and the solubility of each was measured by stirring at 25 ° C. and normal pressure for 30 minutes using a magnetic stirrer. Table 2 shows the measurement results of the solubility of the fullerene derivative (2).

From Table 2, it can be seen that the fullerene derivative (2) has high solubility in PGMEA, 1-methoxy-2-propanol, anisole, ethyl lactate, cyclohexanone, and toluene.

[Average addition numbers (n) and (a)]
Elemental analysis of the fullerene derivative (2) gave the following results.

C: 74.34%
H: 4.61%
N: 9.73%
O: 13%
Considering in the same manner as in Example 1, a value close to the composition of C ₁₁₁ H ₈₄ N ₁₂ O ₁₄ in which the average addition number (n) of the isooxazoline skeleton is 12 and the average addition number (a) of oxygen atoms is 2. Indicated. Here, the calculated values of the composition of C ₁₁₁ H ₈₄ N ₁₂ O ₁₄ are shown below.

C: 73.66%
H: 4.68%
N: 9.29%
O: 12.38%
[Thermal stability]
The thermal stability of the fullerene derivative (2) was evaluated using a thermogravimetric analyzer (TGA).

FIG. 4 shows the results of thermogravimetric analysis of the fullerene derivative (2).

From FIG. 4, it can be seen that the fullerene derivative (2) loses weight at a temperature of 500 ° C. or lower.

[Infrared absorption spectrum]
The infrared absorption spectrum was measured using a Fourier transform infrared spectrophotometer (FT-IR).

FIG. 5 shows an infrared absorption spectrum of the fullerene derivative (2).

[Film film]
0.4 g of the fullerene derivative (2) was dissolved in 3.6 g of PGMEA (manufactured by ALDRICH) and then filtered through a syringe filter having a filter diameter of 0.2 μm to obtain a PGMEA solution of the fullerene derivative (2). A PGMEA solution of the fullerene derivative (2) was applied to a silicon substrate using a spin coater at 1000 rpm for 60 seconds, and then heated and dried at 110 ° C. for 60 seconds to form a film. At this time, since the silicon substrate after the film formation was mirror-shaped, it was confirmed that the fullerene derivative (2) had good film formation properties.

The silicon substrate after the film formation was further heat-treated at 400 ° C. for 300 seconds, and then a part of the film was scraped off to measure the infrared absorption spectrum.

FIG. 6 shows an infrared absorption spectrum of the film after heat treatment.

Comparing FIG. 6 with FIG. 5, the peak of 2900 to 3000 cm ^-1 derived from the CH expansion and contraction of the alkyl group disappeared, and the 2-isooxazoline skeleton was desorbed from the fullerene skeleton by the heat treatment. Was confirmed. Further, since FIGS. 3 and 6 are almost the same, the 2-isoxazoline skeleton was eliminated from the fullerene skeleton of the fullerene derivative (1) and the fullerene derivative (2), so that they were converted into the same compound. Is suggested.

According to the embodiment of the present invention, it exhibits high solubility in various solvents, has good film forming property, and removes functional groups added to the fullerene derivative at a temperature of 500 ° C. or lower. The fullerene derivative that can be separated can be provided by a simple method while avoiding the use of a difficult reagent. Further, since the fullerene derivative can be supplied on an industrial scale and a film having a high carbon content can be provided, it can be industrially used in the field of semiconductor materials and the like.

Claims (6)

General formula (1)

(In the formula, R ₁ is a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, an ester group having 1 to 20 carbon atoms or a heterocyclic group having 1 to 20 carbon atoms, and n is 4 ~ 20, a is 1 to 15, and FLN is a fullerene skeleton.)
Fullerene derivative represented by. The fullerene derivative according to claim 1, wherein R ₁ is an alkyl group or an alkyloxycarbonyl group. A composition containing a plurality of types of fullerene derivatives according to claim 1 or 2. A method for producing a film formed by applying a coating solution in which the fullerene derivative according to claim 1 or 2 is dissolved in an organic solvent to a substrate and then heating the substrate. The method for producing a film according to claim 4, wherein the organic solvent is at least one selected from esters, ethers and aromatics. The method for producing a film according to claim 4 or 5, wherein the heating temperature is 200 to 500 ° C.

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