JP3537869B2 - Oxadiazole compound and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel oxadiazole compound useful as an optical brightener or as a material for an organic electroluminescent device, particularly as an electron transport material, and a method for producing the same.

[0002]

2. Description of the Related Art Various oxadiazole compounds are known as materials for organic electroluminescent devices. See, for example, The Chemical Society of Japan, 1991, (11), p. 1540-154
No. 8 describes an example using an oxadiazole compound as a light emitting material and an electron transporting material. Also, JP-A-3-205479, JP-A-4-212286, JP-A-4-363891, JP-A-4-363
No. 894 also discloses an example using an oxadiazole compound. However, there is still a problem with the stability of the thin film, and an organic electroluminescent device having high luminance and high reliability has not been obtained.

[0003]

SUMMARY OF THE INVENTION The present invention has a stable film-forming property as a material for an organic electroluminescent device, and is particularly useful as a luminescent material, an electron transport material, etc. It is an object of the present invention to provide a novel oxadiazole compound that is difficult to produce and a method for producing the same.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that an oxadiazole compound having a specific structure is effective. Reached. That is, according to the present invention, there is provided an oxadiazole compound represented by the following general formula (I) (Formula 1).

Embedded image (Wherein , A represents a substituted or unsubstituted aromatic hydrocarbon group not containing a tertiary amine structure, and may be the same or different. R is a hydrogen atom, a halogen atom, Represents an unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, or a hydroxyl group.) Further, the following general formula (II):

Embedded image (Wherein, R represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, or a hydroxyl group) by converting the acid halide compound represented by the following general formula (III) (Formula 3) or the general formula (I
V) (Chem. 4)

Embedded image

Embedded image (Wherein, A represents a substituted or unsubstituted aromatic hydrocarbon group not containing a tertiary amine structure , respectively) and reacted with a tetrazole compound represented by the general formula (I). A method for producing an oxadiazole compound, characterized by producing an oxadiazole compound represented by the formula: Further, it is represented by the general formula (I) (Formula 1).
Electric field generation characterized by containing an oxadiazole compound
An optical device is provided.

In the general formula (I), specific examples of the aromatic hydrocarbon group or the aromatic heterocyclic group represented by A include styryl, phenyl, biphenyl, terphenyl,
Naphthyl, anthryl, acenaphthenyl, fluorenyl, phenanthryl, indenyl, pyrenyl, pyridyl, pyrimidyl, furanyl, pyronyl, thiophenyl,
Examples include quinolyl, benzofuranyl, benzothiophenyl, indolyl, carbazolyl, benzoxazolyl, quinoxalyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothiophenyl, oxazolyl, and oxadiazolyl groups.

These aromatic hydrocarbon groups or aromatic heterocyclic groups may further contain at least one halogen atom, hydroxyl group, cyano group, nitro group, amino group, trifluoromethyl group, having 1 to 12, preferably 1 carbon atom. To 6 alkyl groups, 1 to 12 carbon atoms, preferably 1 to 6 alkoxy groups,
It may have a substituent such as an aryloxy group, a phenyl group, a styryl group, a naphthyl group, a thiophenyl group, an aralkyl group, a biphenyl group, a bithiophenyl group, a furanyl group, a bifuranyl group, a pyronyl group, and a bipyronyl group.

In the general formula (I), examples of the substituted or unsubstituted alkyl group for R include an alkyl group having 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms.
Examples of the substituent include a halogen atom, a hydroxyl group, a phenyl group, an alkoxy group, and an amino group. Examples of the substituted or unsubstituted alkoxy group include those having 1 to 1 carbon atoms.
2, preferably 1 to 6 alkoxy groups, and examples of the substituent include a halogen atom, a hydroxyl group, and an amino group.

As described above, the oxadiazole compound of the present invention represented by the general formula (I) has the following general formula (II)
(Formula 2)

Embedded image (Wherein R and X are the same as above) by converting the acid halide compound represented by the following general formula (III) (formula 3) or general formula (IV) (formula 4)

Embedded image

Embedded image (In the formula, A is the same as described above.)

The acid halide compound represented by the general formula (II) (Chemical formula 2) is represented by the following general formula (V) (Chemical formula 5)

Embedded image (Wherein R is the same as described above), and is synthesized by treating with a halogenating agent such as thionyl chloride, phosphorus pentachloride, phosgene, and aluminum chloride.

Formula (III) (Formula 3) and Formula (IV)
The tetrazole compounds of the formula (4) are in a tautomeric relationship, are liable to change each other, and are difficult to be taken out separately. In general, both are mixed. Can be used. The tetrazole compounds represented by the general formulas (III) (formula 3) and (IV) (formula 4) used here are produced by a conventionally known method. For example, it can be synthesized by the method described in Synthesis 71 (1973).

Further, the acid halide represented by the general formula (II) (Chemical formula 2) and the acid halide represented by the general formula (III) (Chemical formula 3) and the general formula (IV)
The reaction with a tetrazole compound represented by the following formula
It is carried out according to the oxadiazole synthesis method of D. Huisgen et al. For example, Angew. Chem., 72, 366 (1960),
Chem. Ber. , 93, 2106 (1960), Tetrahedro
n, 11, 241 (1960), Chem. Ber., 98, 29
66 (1965) can be applied.

The reaction is a reaction between a tetrazole group and a carbonyl halide group. The compound represented by the general formulas (II) and (II) is reacted with the compounds represented by the general formulas (III) and (III) and the general formula (IV).
An oxadiazole compound represented by the general formula (I) (Formula 1) can also be synthesized from a raw material in which the functional group of the compound represented by the formula (4) has been exchanged. That is, the reaction of the tetrazole compound represented by the following general formula (VI) (Chemical formula 6) with the general formula (VII) (Chemical formula 7) also yields the general formula (I)
An oxadiazole compound represented by (Chemical Formula 1) can be synthesized.

Embedded image (Wherein the tetrazole group may include tautomers. R
Is the same as above. )

Embedded image         A-COX (VII) (In the formula, A is the same as above. X represents a halogen atom.)

The oxadiazole compound represented by the general formula (I) (formula 1) can also be synthesized by the following reaction. That is, the following general formula (II) (Formula 2)

Embedded image Wherein R and X are the same as described above, and a compound represented by the following general formula (VIII):

Embedded image A-CONHNH ₂ ... (VIII) (wherein A is as defined above) is reacted with a compound represented by the following general formula (IX).

Embedded image (Wherein A and R are the same as described above), and an oxadiazole compound represented by the general formula (I) (formula 1) is produced by further performing a dehydration reaction. can do.

Further, the oxadiazole compound represented by the general formula (I) (Chemical formula 1) is a compound represented by the following general formula (VII) (Chemical formula 7)

Embedded image A-COX (VII) (wherein, A and X are as defined above);
The following general formula (X)

Embedded image (Wherein, R is the same as described above) to produce a compound represented by the general formula (IX) (Chemical formula 9), and further by performing a dehydration reaction, An oxadiazole compound represented by the general formula (I) (Formula 1) can be produced.

General formula (X) used as a starting material
The compound represented by the general formula (XI) is represented by the following general formula (XI)
1)

Embedded image (In the formula, R is the same as described above, and R ′ represents an alkyl group.)
Can be easily produced by reacting the ester derivative represented by the formula with hydrazine.

The above-mentioned two kinds of synthesis steps of the compound represented by the general formula (IX) (Formula 9) are usually carried out in the presence of a basic catalyst. Examples of the basic catalyst include pyridine and its derivatives, organic bases such as triethylamine, tributylamine, triethanolamine, quinoline, piperazine, and morpholine, and inorganic bases such as sodium hydroxide, potassium hydroxide, and sodium carbonate. Particularly, an organic basic catalyst is preferable. As the reaction solvent in this step, any solvent can be used as long as it can dissolve the compound represented by the general formula (IX) (Chem. 9) at least, but alcohol solvents such as ethanol and butanol, dioxane, Preferred are ether solvents such as tetrahydrofuran, aromatic solvents such as benzene, toluene, chlorobenzene and nitrobenzene, N, N-dimethylformamide, dimethylsulfoxide and the like. Further, an organic basic catalyst such as pyridine described above may be used in excess and used as a solvent.

The step of dehydrating the compound represented by formula (IX) (Chemical Formula 9) and closing the ring is performed by a dehydrating agent such as phosphorus oxychloride, thionyl chloride, polyphosphoric acid, boric acid, toluenesulfonic acid or the like. Perform in the presence of As the reaction solvent at this time, the solvents described in the above steps can be used, but aromatic solvents such as chlorobenzene, dichlorobenzene, xylene, and nitrobenzene, and halogen solvents such as trichloroethane and trichloromethane are particularly preferable. The amount of the dehydrating agent used is from 1 mol to 1 mol per 1 mol of the starting material compound.
About 0 mol is appropriate, but for example, phosphorus oxychloride may be used in a large excess and used as a solvent. Usually, the reaction is 50
Completed in minutes to 10 hours at a temperature between 300C and 300C.

Table 1 shows specific examples of the oxadiazole compound represented by the general formula (I) (formula 1) according to the present invention.

[0019]

[Table 1- (1)]

[0020]

[Table 1- (2)]

The oxadiazole compound represented by the general formula (I) of the present invention is particularly excellent as a constituent component of an organic electroluminescent device. For example, the oxadiazole compound is formed into a thin film by a vacuum deposition method, a solution coating method, etc. The element can be obtained by directly or indirectly holding the element.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments. Note that the present invention is not limited by these examples.

Synthesis Example 1 Synthesis of a compound represented by the following structural formula (Formula 12) [General formula (II), R = H, X = Cl]

Embedded image 10 g of 2,6-naphthalenedicarboxylic acid and 60 ml of thionyl chloride were placed in a reaction vessel and heated to reflux. Thereafter, unreacted thionyl chloride was removed by distillation under reduced pressure, and dichloroethane 10
0 ml was added and the mixture was recrystallized to obtain 5 g (yield: 42.7%) of the target product as slightly yellowish needles. The melting point of this product was from 187 ° C to 189 ° C. In the infrared absorption spectrum (KBr tablet method), CO
An absorption at 1750 cm ^-1 attributed to stretching vibration was observed.

Synthesis Example 2 Synthesis of compound represented by the following structural formula (Formula 13) [General formula (III), A = biphenyl-
4-yl]

Embedded image 20.0 g of p-cyanobiphenyl and 7.9 of sodium azide
8 g and 6.57 g of ammonium chloride are placed in a reaction vessel,
55 ml of N, N-dimethylformamide was added as a solvent, and the mixture was heated and refluxed at 100 ° C to 110 ° C for 15 hours. After allowing to cool, pour the reaction mixture into 500 ml of water, filter, and add 500 ml of water.
After washing with water, 24.0 g of the crude product (yield 96.8) was obtained.
%). This was recrystallized from 650 ml of dioxane to obtain 9.94 g (yield: 40.1%) of a white powder. The decomposition point of this compound is 239.5 ° C to 240.3 ° C.
Met. The infrared absorption spectrum is from 3200 cm ^-1
A broad peak attributable to the NH stretching vibration of tetrazole was observed at 2500 cm ^-1 , confirming that the compound was the target compound.

Synthesis Example 3 Synthesis of a compound represented by the following structural formula (Formula 14) [General formula (III), A = 2-naphthyl]

Embedded image 10 g of 2-cyanonaphthalene and 10.61 sodium azide
g and 7.67 g of lithium chloride were put in a reaction vessel, 240 ml of 2-methoxyethanol was added as a solvent, and the mixture was heated under reflux for 80 hours. After allowing to cool, 500 ml of water was added, and insoluble materials were removed by filtration, and 13.5 ml of 35% hydrochloric acid was added. The precipitate was filtered and washed with water to obtain 12.17 g of a crude product. Furthermore, 340 ml of toluene and 140 ml of dioxane
Recrystallized with a mixed solvent of 9.1 to give colorless needles of the desired product 9.1.
4 g were obtained (71.4% yield). When the melting point of this compound was measured, the compound foamed and decomposed at 205.5 ° C. to 205.8 ° C. The infrared absorption spectrum is 3200 cm ^-1 to 250
A broad peak attributed to the NH stretching vibration of the tetrazole group was observed at 0 cm ^-1 .

Synthesis Example 4 Compound No. Synthesis of 21 [General Formula (I), A = 2-naphthyl, R = H] 1.28 g of the acid chloride compound obtained in Synthesis Example 1 and 2.08 g of the tetrazole compound obtained in Synthesis Example 3 are placed in a reaction vessel. Pyridine 4 which was put and dehydrated with molecular sieve
0 ml was added as a solvent, and the mixture was heated under reflux for 15 hours. After cooling, 60 ml of methanol was added, and the precipitate was filtered and washed with methanol to obtain 2.5 g of a crude product. Thereafter, the product was recrystallized from 100 ml of nitrobenzene to obtain 2.31 g of the target product as pale yellow needles (yield: 88.5%). Also organic E
Prior to application to the L element, it was heated to 350 ° C. in a temperature gradient tube under a stream of argon gas having a degree of vacuum of 30 Pa to perform sublimation purification before use. The melting point of this compound was 300 ° C. or higher. FIG. 1 shows the infrared absorption spectrum (KBr tablet method).

[0027]

[Table 2]

Synthesis Example 5 Compound No. Synthesis of 23 [general formula (I), A = 4-biphenylyl, R = H] 1.15 g of the acid chloride compound obtained in Synthesis Example 1 and 2.13 g of the tetrazole compound obtained in Synthesis Example 2 were placed in a reaction vessel. Pyridine 5 in water and dehydrated with molecular sieve
0 ml was added as a solvent, and the mixture was heated under reflux for 11 hours. After cooling, 50 ml of methanol was added, and the precipitate was filtered and washed with methanol to obtain 2.41 g of a crude composition. This was recrystallized with 100 ml of nitrobenzene to obtain 2.41 g of the target product as colorless plate crystals (yield 94.9%). Further, in a temperature gradient tube under an argon gas flow having a vacuum degree of 30 Pa, 36
Sublimation purification was performed by heating to 0 ° C. The melting point of this compound was 358.7 ° C. (DTA peak value). FIG. 1 shows the infrared absorption spectrum (KBr tablet method).

[0029]

[Table 3]

Application Example 1 Size 2 mm × 2 mm, thickness 170 nm on a glass substrate
An anode made of indium tin oxide (ITO) is formed thereon, and a hole transport layer 40 nm composed of a diamine derivative represented by the following formula (XV) (formula 15) is further formed thereon. A diamine represented by the following formula (XVI) (formula 16) Light emitting layer 15n made of derivative
m, the compound No. Electron transport layer 20n of 23
m, an electron transport layer 3 represented by the following formula (XVII) (Formula 17)
0 nm, a 10: 1 atomic ratio MgAg electrode at 300 nm,
Each was formed by vacuum evaporation to produce an electroluminescent device.
The degree of vacuum during the deposition is 0.7 × 10 ⁻⁶ Torr, and the substrate temperature is room temperature. When a DC power supply was connected to the anode and the cathode of the device thus manufactured via a lead wire, the applied voltage was 1 at a current density of 175 mA / cm ² .
Blue light emission with a luminance of 17 cd / m ² at 7.4 V was observed. It should be noted that light emission of this device was clearly confirmed even after storage for 3 months.

Embedded image

Embedded image

Embedded image

Application Example 2 The compound No. Compound No. 23 instead of Compound No. 23 An electroluminescent device was produced in the same manner as in Application Example 1 except that Sample No. 21 was used. When a DC power supply was connected to the anode and the cathode of the fabricated device via a lead wire, the current density was 135 mA / cm ^2.
And the applied voltage is 17.7 V and the luminance is 14 cd /
A blue-green emission of m ² was observed.

Comparative Example The above compound No. The following compound (XVIII) in place of 23
An EL element was manufactured in the same manner as in Application Example 1 except that (Formula 18) was used. When a DC voltage was applied to this device, clear blue light emission was observed. However, no EL emission was observed after storage for one month.

Embedded image

[0033]

The oxadiazole compound of the present invention is a novel compound and can easily form a uniform transparent film by vapor deposition or the like, and has an excellent function as an electron transporting material for an organic electroluminescent device. With a high melting point
Since there is little deterioration over time, it is useful as a highly reliable material for organic electroluminescence. Further, according to the present invention, an advantageous method for producing the oxadiazole compound can be provided.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum (KBr tablet method) of an oxadiazole compound of the present invention [A = 2-naphthyl, R = H in the general formula (I)].

FIG. 2 is an infrared absorption spectrum (KBr tablet method) of the oxadiazole compound of the present invention [A = 4-naphthyl, R = H in the general formula (I)].

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI (C07D 413/14 C07D 271: 10 271: 10 333: 10 333: 10) C07D 213: 16 : 16 271: 00 271: 10) C07D 215: 04 (C07D 413/14 309: 00 209: 32 271: 00) (C07D 413/14 215: 04 271: 10) (C07D 413/14 271: 10 309: 00) (56) References French Patent Application Publication No. 1397516 (FR, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07D 271/10 CAPLUS (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] An oxadiazole compound represented by the following general formula (I): Embedded image (Wherein , A represents a substituted or unsubstituted aromatic hydrocarbon group not containing a tertiary amine structure, and may be the same or different. R is a hydrogen atom, a halogen atom, Represents an unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, or a hydroxyl group.) 2. The following general formula (II): (Wherein, R represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, or a hydroxyl group) by converting the acid halide compound represented by the following general formula (III) (Formula 3) or the general formula (I
V) (Chemical formula 4) Embedded image (Wherein A represents a substituted or unsubstituted aromatic hydrocarbon group not containing a tertiary amine structure , respectively), and reacted with a tetrazole compound represented by the following general formula (I). Embedded image (In the formula, A represents a substituted or unsubstituted aromatic hydrocarbon group not containing a tertiary amine structure, which may be the same or different. R represents a hydrogen atom, a halogen atom, A oxadiazole compound represented by an unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, or a hydroxyl group). 3. The oxadiazole compound according to claim 1,
An electroluminescent device comprising: