JP2002114773A - Novel red light-emitting compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel red light-emitting compound that has large emission brightness with high color retention. SOLUTION: In this novel light-emitting compound, a fluorine-bearing electron- attractive group is introduced into the coumarin skeleton and an electron- donating group is introduced into the benzene ring, thus the resulting compound emits Nile red light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel red light-emitting compound, and more particularly, to a novel red light-emitting compound capable of emitting red light with high luminance when electric energy is applied.

[0002]

2. Description of the Related Art Conventionally, various organic compounds have been proposed as organic electroluminescent devices (also referred to as organic electroluminescent devices or organic EL devices).

However, at present, an organic compound having a coumarin skeleton and capable of emitting red light with high luminance has not yet been developed. Further, a compound capable of emitting red light which does not fade over time has not yet been developed.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel red light-emitting compound which has a high emission luminance and is not easily faded with time among organic compounds having a coumarin skeleton, and a light-emitting element using the same. It is in.

[0005]

Means for Solving the Problems A first invention for solving the above problems is a novel red light emitting compound having a structure represented by the following formula (1).

[0006]

Embedded image (Where A is a fluorine atom-containing aromatic hydrocarbon group or a substituent represented by the following formula (2), B is —NR ¹ R ² , and R ¹ and R ² are hydrogen atoms , Having 1 to 1 carbon atoms
3 represents a lower alkyl group or — (CH ₂ ) _n — bonded to the carbon at the ortho position in the benzene nucleus to which B is bonded, and the hydrogen atom in this methylene group is substituted by an alkyl group having 1 to 3 carbon atoms. May be. n shows the integer of 2-4. R ¹ and R ² may be the same or different. R ⁵ and R ⁶ are a hydrogen atom or a CN group. R ⁵ and R ⁶ may be the same or different. )

[0007]

Embedded image

BEST MODE FOR CARRYING OUT THE INVENTION The luminescent compound according to the present invention is represented by the general formula (1).

In the general formula (1), A is a fluorine-containing aromatic hydrocarbon group or a substituent represented by the above formula (2).

Examples of the fluorine-containing aromatic hydrocarbon group A include an aromatic hydrocarbon group which substitutes a fluorine or fluorinated alkyl group. Examples of the aromatic group in the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an anthracenyl group, a biphenyl group, and a terphenyl group.

The preferred fluorine-containing aromatic hydrocarbon group A includes an aromatic hydrocarbon group represented by the formula (3).

[0011]

Embedded image In the formula, R ³ is a fluorine atom or a fluorine atom-containing alkyl group, and preferably has a fluorine atom or a carbon number of 1 to 1.
5 and a fluorinated alkyl group that substitutes a fluorine atom. Examples of the fluorine atom-containing alkyl group include an alkyl group bonding —CF ₃ in the alkyl main chain, an alkyl group bonding a fluorine atom in the alkyl main chain, and the like. As such a fluorine atom-containing alkyl group, specifically, 5,5,5, -trifluoropentyl group, 5,4,3-trifluoropentyl group, 4,3,2
-Trifluoropentyl group, 4,4,4-trifluorobutyl group, 3,3,3-trifluoropentyl group, 2,
2,2-trifluoroethyl group, trifluoromethyl group, 1,2,3,4,5-pentafluoropentyl group,
1,2,3,4-tetrafluoropentyl group, 1,2,2
3-trifluoropentyl, 1,1-difluoropentyl, 1,1-difluoropropyl, 2,3-difluorobutyl, trifluoromethyl, difluoromethyl, 1,2-difluoroethyl, and the like. be able to. M indicating the number of R ³ bonded to the benzene ring is 1
To 5, preferably 1 and 2.

Of the various fluorine-containing alkyl groups, a trifluoromethyl group is preferred.

Among the aromatic hydrocarbon groups represented by the formula (3), a 4-trifluoromethylphenyl group and a 3,5-
A di-trifluoromethylphenyl group is preferred.

In the above formula (1), B is -NR ¹ R ² , wherein R ¹ and R ² are a hydrogen atom, a lower alkyl group having 1 to 3 carbon atoms, or a carbon atom at the ortho position in the benzene nucleus to which B is bonded. And-(CH ₂ ) _n- which binds to N is 2 to
4 is an integer. R ¹ and R ² may be the same or different.

This -NR¹R^TwoSpecific examples of
Group, monomethylamino group, dimethylamino group, monoethyl
Ruamino group, diethylamino group, monopropylamino
Group, a dipropylamino group, etc., and a ring structure represented by the formula (4)
A forming group can be indicated. In this equation (4), carbon bone
The case is indicated, but the nitrogen atom and the aromatic ring
Hydrogen atoms and / or carbon atoms
Alkyl groups of formulas 1 to 3 are bonded. Shown in equation (4)
A preferred ring structure group is a group represented by-(CH_Two) _Three-N
− (CH_Two)_Three-And -CR⁷ _Two-CH_Two-CH_Two-NC
H_Two-CH_Two-CR⁸ _Two− (However, the bonds at both ends are
Attached to carbon forming an aromatic ring. R⁷Is a hydrogen atom or
An alkyl group having 1 to 3 carbon atoms,⁷One of
Is an alkyl group having 1 to 3 carbon atoms. R⁸Is a hydrogen atom or
Is an alkyl group having 1 to 3 carbon atoms, and two R⁸One of
One is an alkyl group having 1 to 3 carbon atoms. ).

[0016]

Embedded image The light emitting compound represented by the general formula (1) can be produced, for example, according to the reaction formula shown in FIG. 1 as follows.

As shown in FIG. 1, compound (A) and NC-CH ₂ -COOR ⁴ are first heated in a solvent to synthesize compound (B).

The compound (C) is synthesized by reducing the obtained compound (B). In the reduction, a reduction catalyst such as Raney nickel can be used.

The compound (C) obtained is represented by the formula: A-CH ₂ -C
N (compound (D), wherein A has the same meaning as described above), wherein R ⁵ and R ⁶ in the structure represented by formula (1) are hydrogen atoms. Such a novel red light emitting compound is synthesized. The reaction between compound (C) and compound (D) can be carried out in a solvent. Examples of the solvent include a mixed solvent of an amine such as piperidine and a lower alcohol such as ethanol, dimethylformamide, and acetic anhydride. And the like.

A novel red light-emitting compound in which R ⁵ and R ⁶ in the structure represented by the formula (1) are cyano groups is represented by R ⁵
And a compound of the formula (1) wherein R ⁶ is a hydrogen atom, by reacting NaCN in the presence of an oxidizing agent such as lead tetraacetate or the like.

The novel red light emitting compound according to the present invention is used for a light emitting device. This light-emitting element has a structure in which a film made of a composition containing a novel red light-emitting compound is formed on a substrate and a surface of the substrate, and a metal electrode is formed on the surface of the film.

As the substrate, for example, a transparent substrate such as glass, plastic or the like is formed on an ITO or In
It can be formed of a transparent conductive material such as ₂ O ₃ , SnO ₂ , ZnO, CdO, or a compound thereof.

The composition comprises a novel red light-emitting compound,
2,5-bis (1-naphthyl) -1,3,4-oxadiazole and 2- (4-tert-butylphenyl) -5
An oxadiazole derivative such as-(4-biphenylyl) -1,3,4-oxadiazole, and an electron transporting agent such as 2,5-bis (5′-tert-butyl-2′-benzoxazolyl) thiophene; A hole transporting agent such as polyvinyl carbazole.

In this composition, the content of the novel red light-emitting compound is usually from 0.01 to 10% by weight, preferably from 0.1 to 5% by weight. When the content of the novel red light-emitting compound is within the above range, red light emission occurs more vividly than when the content is outside the range.

The content of the electron transport agent is usually from 1 to 80.
% By weight, preferably 10 to 50% by weight.

The composition interposed between the substrate and the metal electrode has a thickness of usually 30 to 300 nm, preferably 5 to 300 nm.
0 to 200 nm. When the thickness of the composition is within the above range, there is an advantage that the luminance becomes higher at a low voltage than when the thickness is outside the range.

The film made of the composition on the substrate is as follows:
For example, it can be formed by a normal film forming technique such as a spin coating method, a coating method, and a casting method.

The metal electrode may be a simple metal or a metal alloy. A preferred metal electrode is an alloy electrode of aluminum and a small amount of lithium. This metal electrode can be easily formed, for example, on the surface of a film of the composition formed on a substrate by a vapor deposition technique.

The light emitting device according to the present invention can be generally used, for example, as a DC drive type device, and can also be used as a pulse drive type device and an AC drive type device. Since the melting point of each of the novel red light emitting compounds is 100 to 400 ° C., an EL device can be manufactured by vapor deposition. In this case, the red compound can also be used as a host dye and dopant. Since the light-emitting device according to the present invention contains a novel red light-emitting compound, the light-emitting device emits light with high luminance and does not easily fade over time.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference is made to FIG.

Example 1 Synthesis of Compound in FIG. 2 In a 500 ml three-necked flask, 13 g (67.3 mmol) of 4-diethylaminosalicylaldehyde, 7.61 g (67.3 mmol) of ethyl cyanoacetate, 100 ml of ethanol, 5.73 g of piperidine (67.3 mmo
l) was added, and the mixture was reacted for 3.5 hours with stirring while heating to 60 ° C. with a water bath. After the reaction, the mixture was cooled on ice, and the precipitated solid was filtered through a glass filter to obtain 14 g of a yellow solid. The yield in this reaction was 86%, and the melting point of the obtained compound was 225 to 226 ° C.

FIG. 3 shows an IR chart of this compound.

The results of elemental analysis of this compound are shown below.

Elemental analysis result Obtained value: C; 69.42 H; 5.84 N; 11.45 Calculated value: C; 69.40 H; 5.82 N; 11.56 Synthesis of compound in FIG. 8.0 g of the compound (1
9.9 mmol), 75 ml of a 75% formic acid aqueous solution and 5.0 g of Raney nickel were added, heated to 135 ° C. using a silicon oil bath, and reacted for 1 hour. After the reaction, the reaction solution was filtered, the residue was washed with hot ethanol, and the obtained filtrate was extracted with chloroform, added with sodium sulfate, allowed to stand, and dehydrated. The solution was concentrated and recrystallized from ethanol to obtain 2.1 g of an ocher solid. The yield in this reaction was 24%, and the melting point of the compound was 162-164 ° C. FIG. 4 shows an IR chart and FIG. 5 shows an NMR chart of this compound. The results of elemental analysis of the compound are shown below.

Elemental analysis results Obtained value: C; 68.66 H; 5.96 N; 5.69 Calculated value: C; 68.55 H; 6.16 N; 5.71 Synthesis of the compound shown in FIG. 0.48 g of compound in a 200 ml three-necked flask
(1.98 mmol), 0.50 g of 3,5-bis (trifluoromethyl) phenylacetonitrile (1.98 m
mol), ethanol 20 ml, piperidine 0.17 g
(1.98 mmol) and 60 ° C in a water bath
The mixture was reacted for 1.5 hours with stirring while heating to 1.5 hours. After the reaction, the mixture was cooled on ice, and the precipitated solid was filtered with a glass filter to obtain 0.70 g of a red-purple solid. The yield in this reaction was 78%. The melting point of the obtained compound is 218.
２２０220 ° C. Fig. 6 shows the IR chart of the compound.
FIG. 7 shows an NMR chart. The results of the compound analysis are shown below.

Elemental analysis results Obtained value: C; 58.73 H; 3.01 N; 6.04 Calculated value: C; 58.55 H; 2.90 N; 6.21 Synthesis of compound shown in FIG. 0.40 g of compound in a 200 ml three-necked flask
(1.63 mmol), 0.30 g of 4- (trifluoromethyl) phenylacetonitrile (1.63 mmol)
l), ethanol 20 ml, piperidine 0.14 g
(1.63 mmol) and 60 ° C in a water bath
The reaction was carried out for 7.0 hours with stirring while heating to. After the reaction, the mixture was cooled on ice, and the precipitated solid was filtered with a glass filter to obtain 0.43 g of a red solid. The yield in this reaction was 69% and the melting point was 214 to 216 ° C. The IR chart of the compound is shown in FIG. The results of elemental analysis of the compound are shown below.

Elemental analysis result Observed value: C; 68.75 H; 4.99 N; 10.03 Calculated value: C; 68.81 H; 4.77 N; 10.47 Synthesis of compound shown in FIG. 0.34 g of compound in a 200 ml three-necked flask
(1.39 mmol), 0.24 g (1.39 mmol) of 2-benzothiazoleacetonitrile, ethanol 2
0 ml and piperidine 0.12 g (1.39 mmol) were added, and the mixture was reacted for 2.0 hours while stirring at 60 ° C. in a water bath. After the reaction, the mixture was cooled on ice, and the precipitated solid was filtered with a glass filter to obtain 0.43 g of a purple solid. The yield in this reaction is 72% and the melting point is 23
5-240 ° C. Fig. 9 shows the IR chart of the compound.
The NMR chart is shown in FIG. The results of elemental analysis of the compound are shown below.

Elemental analysis result Obtained value: C; 69.42 H; 5.84 N; 11.45 Calculated value: C; 69.40 H; 5.82 N; 11.56 The fluorescence spectrum of this compound is shown in FIG. FIG. 12 shows the absorption spectrum. The fluorescence spectrum was obtained by measuring a dioxane solution of the above compound having a concentration of 2 × 10 ⁻⁴ g / l as a sample and measuring with a Shimadzu fluorescence spectrophotometer (RF-1500). The absorption spectrum was obtained by using a dioxane solution of the compound having a concentration of 2 × 10 ⁻⁶ mol / l as a sample and measuring the absorbance with a spectrophotometer (Ubest-55) manufactured by JEOL Ltd.

Synthesis of Compound shown in FIG. 2 0.20 g of the compound was placed in a 200 ml three-necked flask.
(0.443 mmol), 10 ml of N, N-dimethylformamide, and 0.043 g of sodium cyanide
(0.443 mmol) was added and stirred for 10 minutes. There, 0.40g of lead tetraacetate (0.443mo
l) was added and stirred for 10 minutes. Pour the reaction solution into water,
Extraction was performed using chloroform, and purification was performed by column chromatography using silica gel and benzene to obtain 0.10 g of a blue-violet solid. The yield in this reaction was 30%, and the melting point of the compound was 206 to 208 ° C. FIG. 13 shows an IR chart of the compound and FIG. 1 shows an NMR chart of the compound.
The results are shown in FIG. The results of elemental analysis of the compound are shown below.

Elemental analysis result Obtained value: C; 57.83 H; 2.31 N; 11.02 Calculated value: C: 57.50 H; 2.21 N; 11.17 The fluorescence spectrum of this compound is shown in FIG. FIG. 16 shows the absorption spectrum. As shown in FIG. 15, this compound emits red light because of its emission wavelength peak at 610 nm. From FIG. 16, it is inferred that the luminance is large. The fluorescence spectrum and the absorption spectrum were measured in the same manner as for the compound.

(Embodiment 2) FIG.
See Synthesis of compound shown in FIG. 17 Compound (see FIG. 2) was placed in a 200 ml three-necked flask.
Was added in an amount of 0.20 g (0.522 mmol) and 10 ml of N, N-dimethylformamide.
050 g (0.522 mmol) of an aqueous solution was added, and 1
Stirred for 0 minutes. 0.46 g of lead tetraacetate (0.52 g)
2 mol) and stirred for 10 minutes. The reaction solution was poured into water, extracted with chloroform, and repeatedly purified by column chromatography using silica gel and benzene to obtain 0.12 g of a blue-violet solid. The yield of this reaction is 5
3% and the melting point was 120-122 ° C. FIG. 18 shows an IR chart and FIG. 19 shows an NMR chart of this compound.

The results of elemental analysis of this compound are shown below.

Elemental analysis result Obtained value: C; 63.56 H; 2.88 N; 12.90 Calculated value: C; 63.75 H; 2.79 N; 12.93 Synthesis of the compound shown in FIG. In an eggplant-shaped flask, 1.0 g (3.76 mmol) of NKX-1770 purchased from Hayashibara Biochemical Laboratory,
75% formic acid aqueous solution 12ml, Raney nickel 0.52g
Was heated to 135 ° C. using a silicone oil bath and reacted for 1 hour. After the reaction, the reaction solution was filtered, the residue was washed with hot ethanol, and the obtained filtrate was extracted with chloroform, added with sodium sulfate, allowed to stand, and dehydrated. The solution was concentrated and recrystallized using ethanol to obtain 0.42 g of a red solid. The yield of this reaction is 41
%, And the melting point was 178 to 180 ° C. The IR chart of this compound is shown in FIG.

The results of elemental analysis of this compound are shown below.

Elemental analysis result Obtained value: C; 71.10 H; 5.81 N; 5.11 Calculated value: C; 71.36 H; 5.61 N; 5.20 Synthesis of compound shown in FIG. 0.20 g of compound in a 200 ml three-necked flask
(0.743 mmol), 0.19 g of 3,5-bis (trifluoromethyl) phenylacetonitrile (0.74 mmol)
3 mmol), ethanol 20 ml, piperidine 0.0
63 g (0.743 mmol) was added, and the mixture was reacted for 2.5 hours while stirring at 60 ° C. in a water bath. After the reaction, the mixture was cooled on ice, and the precipitated solid was filtered with a glass filter to obtain 0.24 g of a red solid. The yield of this reaction was 64%, and the melting point was 254 to 255 ° C. FIG. 21 shows an IR chart and FIG. 22 shows an NMR chart of this compound.

The results of elemental analysis of this compound are shown below.

Elemental analysis result Obtained value: C; 62.10 H; 3.48 N; 5.66 Calculated value: C; 61.91 H; 3.60 N; 5.55 Compound (10) shown in FIG. Compound 0.16 g in a 200 ml three-necked flask
(0.317 mmol) and 10 ml of N, N-dimethylformamide, and 0.030 g of sodium cyanide
(0.634 mmol) and stirred for 10 minutes. There, 0.28g of lead tetraacetate (0.634mmo
l) was added and stirred for 10 minutes. Pour the reaction solution into water,
The mixture was extracted with chloroform, added with sodium sulfate, allowed to stand, and dehydrated. The solution was concentrated using an evaporator, and purified by column chromatography using silica gel and benzene to obtain 0.10 g of a blue-violet solid. The yield of this reaction was 57%, and the melting point was 220 to 222 ° C. FIG. 23 shows an IR chart of this compound (10).
The MR chart is shown in FIG.

The results of an elemental analysis of the compound (10) are shown below.

Elemental analysis result Observed value: C; 64.01 H; 3.10 N; 5.28 Calculated value: C; 63.88 H; 3.06 N; 5.32 Fluorescence spectrum of compound (10) Is shown in FIG.

[0050]

According to the present invention, it is possible to provide a compound capable of emitting red light, which has a high luminance and is hardly faded with time, which could not be obtained conventionally.

According to the present invention, it is possible to provide a novel red light-emitting compound which is suitable for an element which emits red light which has high luminance and is not easily faded with time.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a reaction formula for synthesizing a novel red light-emitting compound represented by Formula 1.

FIG. 2 is an explanatory diagram showing a reaction formula for synthesizing compounds 1 to 3 in Example 1.

FIG. 3 is a chart showing an IR chart of the compound in Example 1.

FIG. 4 is a chart showing an IR chart of the compound in Example 1.

FIG. 5 is a chart showing an NMR chart of the compound in Example 1.

FIG. 6 is a chart showing an IR chart of the compound in Example 1.

FIG. 7 is a chart showing an NMR chart of the compound in Example 1.

FIG. 8 is a chart showing an IR chart of the compound in Example 1.

FIG. 9 is a chart showing an IR chart of the compound in Example 1.

FIG. 10 shows the NM of the compound in Example 1.
It is a chart figure showing an R chart.

FIG. 11 is a chart showing an emission wavelength of a compound in Example 1 and an explanatory diagram showing a wavelength peak.

FIG. 12 is a chart showing the absorbance of the compound in Example 1.

FIG. 13 shows the IR of the compound in Example 1.
It is a chart figure showing a chart.

FIG. 14 shows the NM of the compound in Example 1.
It is a chart figure showing an R chart.

FIG. 15 is a chart showing an emission wavelength of a compound in Example 1 and an explanatory diagram showing a wavelength peak.

FIG. 16 is a chart showing the absorbance of the compound in Example 1.

FIG. 17 shows compounds of Example 2 to (10).
FIG. 3 is an explanatory view showing a reaction formula for synthesizing the formula.

FIG. 18 shows the IR of the compound in Example 2.
It is a chart figure showing a chart.

FIG. 19 shows the NM of the compound in Example 2.
It is a chart figure showing an R chart.

FIG. 20 is a chart showing an IR chart of the compound in Example 2;

FIG. 19 shows the IR of the compound in Example 2.
It is a chart figure showing a chart.

FIG. 22 shows the NM of the compound in Example 2.
It is a chart figure showing an R chart.

FIG. 23 shows I of compound (10) in Example 2.
It is a chart figure showing an R chart.

FIG. 24 shows N of compound (10) in Example 2.
It is a chart figure showing an MR chart.

FIG. 25 is a chart showing an emission wavelength of compound (10) and an explanatory diagram showing a wavelength peak in Example 2.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 33/14 H05B 33/14 B (72) Inventor Akio Tajima 1-33-15 Kokubukita, Ebina-shi, Kanagawa Leo Palace BP246 Building A 105 (72) Inventor Hidemasa Mohri 2-6-9 Minamiseya, Seya-ku, Yokohama-shi, Kanagawa F-term (reference) 3K007 AB02 AB04 AB11 DA01 DB03 EB00 4C062 EE31 4C063 AA01 BB04 CC79 DD62 EE10

Claims (1)

[Claims] 1. A novel red light-emitting compound having a structure represented by the following formula (1). Embedded image (Where A is a fluorine atom-containing aromatic hydrocarbon group or a substituent represented by the following formula (2), B is —NR ¹ R ² , and R ¹ and R ² are hydrogen atoms , Having 1 to 1 carbon atoms
3 represents a lower alkyl group or — (CH ₂ ) _n — bonded to the carbon at the ortho position in the benzene nucleus to which B is bonded, and the hydrogen atom in this methylene group is substituted by an alkyl group having 1 to 3 carbon atoms. May be. n shows the integer of 2-4. R ¹ and R ² may be the same or different. R ⁵ and R ⁶ are a hydrogen atom or a CN group. R ⁵ and R ⁶ may be the same or different. )