KR100449954B1 - NOVEL BRANCHED α-CYANOSTILBENE FLUOROPHORES - Google Patents

Abstract

The present invention relates to a branched α-cyanostilbene-based emitter of a novel structure that can be used in an electroluminescence display (ELD), a powder having a stilbene-based core structure and a branched phenyl structure at the end, Organic solutions in the form of solutions and films.

The phosphor of the present invention has high luminous efficiency and color tuning of red, green and blue is possible according to the structure of stilbene, which is a core structure in the molecule, and especially when in a solid state than in a solution state. Higher luminescence is seen.

Description

NOVEL BRANCHED α-CYANOSTILBENE FLUOROPHORES

The present invention relates to branched organic light emitting bodies having a stilbene-based core structure capable of various color control of red, green, and blue.

In recent years, organic EL devices have attracted attention as candidates for high brightness flat panel displays. According to this tendency, many researches and developments about this are actively progressed. The organic EL device has a structure in which a light emitting layer is inserted between two electrodes. Holes injected into the anode and electrons injected from the cathode recombine and emit light in the emission layer. Both high molecular weight and low molecular weight materials can be used in the manufacture of organic EL devices, both of which have been demonstrated to provide high brightness organic EL devices.

Organic EL devices are divided into two types. One type is to form a light emitting layer using a fluorescent transporting charge transport material (Journal of the Applied Physics, 65, 3610, 1989), and the other type is to use a fluorescent color element as a light emitting layer (Japanese Journal of the Applied Physics, 27, L269, 1988).

The organic EL device using the fluorescent color element body as a light emitting layer is further divided into the following three types. The first is a three-layer device in which the light emitting layer is interposed between the hole transport layer and the electron transport layer, the second is a two-layer device in which the hole transport layer and the light emitting layer are stacked on the other one, and the third is a two-layer device in which the electron transport layer and the light emitting layer are stacked on the other one. . Therefore, it is known that an organic EL device exhibits improved luminous efficiency when it has a two-layer or three-layer structure.

In the above organic EL device, the electron transport layer contains an electron transport compound and has a function of transferring electrons injected from the cathode to the light emitting layer. Both the hole injection layer and the hole transport layer contain a hole transport compound and have a function of transferring holes injected from the anode to the light emitting layer. When the hole injection layer is inserted between the anode and the light emitting layer, an increased number of holes can be injected into the light emitting layer at a low electric field, and electrons injected from the cathode or the electron injection layer can be limited in the light emitting layer, thereby improving luminous efficiency. In this way, an organic EL device having excellent light emission performance can be realized.

Various materials concentrated on triphenylamine derivatives used in the prior art are widely known as materials used in such organic EL devices, but only a very small number of materials are suitable for practical use. By way of example, N, N'-diphenyl-N, N'di (3-methylphenyl) -4,4'-diaminophenyl (TPD) (Applied Physics Letter, Vol. 57, No. 6, 531, 1990) It is known that this compound is thermally unstable and has problems in the lifetime of the resulting device. Many other triphenylamine derivatives are known (US Pat. Nos. 5047686, 4047948 and 4536457, Japanese Patent Publications 6-32307 and Japanese Patent Application Publication Nos. 234681, 5-239455, 8-87122 and 8-259940), most of which are unsatisfactory in terms of properties.

The star-burst amine derivatives disclosed in Japanese Patent Application Laid-Open No. 4-308688 or 6-1972 or in Advanced Material, Vol. 6, 577, 1994 are actually essential for organic EL devices. Does not meet the requirements, that is, high luminous efficiency and long life, and Japanese Patent Application Laid-Open Nos. 7-126226, 7-126615, 7-331238, 7-97355, 8-48656 and 8 Each of the compounds disclosed in 8-100172 and the Journal of the Chemical Society Chemical Communication, p2175, 1996 also fail.

Compounds having a thiophene ring disclosed in Advanced Material Vol. 9, 720, 1997 have the disadvantage of emitting long wavelengths of light.

As described above, materials used in conventional organic EL devices still require improved performance, and therefore, excellent materials capable of improving the light emitting performance of organic EL devices are required.

In view of the foregoing, the inventors of the present invention synthesize new branched stilbene derivatives in an attempt to solve problems related to conventional organic EL devices and to impart new performance, and by using them, the performance required as organic EL devices is improved. It has been found that implementation has led to the completion of the present invention.

Accordingly, it is an object of the present invention to provide new organic fluorescent materials.

Still another object of the present invention is to provide new organic fluorescent materials capable of color control of red, green, and blue.

1 is a diagram showing an ultraviolet absorption spectrum of synthesized organic light emitting bodies.

2 is a diagram showing a fluorescence emission spectrum in the solid state of the synthesized organic light emitting bodies.

3 is a diagram showing an electroluminescence spectrum in the solid state of the synthesized organic light emitting bodies.

4 is a diagram showing the results of thermogravimetry analysis (TGA) of the synthesized organic light emitting bodies.

5 is a diagram showing the basic structure of a novel branched α-cyanostilbene-based organic light-emitting body exhibiting luminescence properties.

The invention will be described in detail in the following.

Branched α-cyanostilbene derivatives according to the present invention are polyphenyl derivatives having the general formula (1), which may be prepared by the method shown in Examples 1 to 13 below:

[In the meal, R ₂ and R ₃ represent a C1-C6 alkyl group, a C1-C6 alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, and a substituted or unsubstituted aryl group or substituted Or an unsubstituted heterocyclic group can be condensed at any position of the corresponding benzene ring and benzene ring.

The branched α-cyanostilbene derivatives of the formula 1 of the present invention are used in the composition in an amount of 1 to 99% by weight based on the total weight of the organic electroluminescent composition.

Meanwhile, the manufactured stilbene-based phosphors exhibit ultraviolet absorption as shown in FIG. 1, and exhibit fluorescence emission characteristics as shown in FIG. 2 and electroluminescence characteristics as shown in FIG. 3. In particular, the materials of the present invention can be said to be an invention in which all of the fluorescent colors are emitted in the whole color (red, green, blue) region, thereby changing the core structure in the branched basic structure, and allowing color tuning.

In addition, most of the materials of the present invention showed the initial decomposition temperature at 350 ~ 400 ℃ (Fig. 4), all showed high thermal stability.

Hereinafter, a method of preparing the branched α-cyanostilbene derivatives of the formula (1) will be described.

EXAMPLES 1-8

Preparation of Compounds for Use in Preparation of Branched α-Cyanostilbene Derivatives of Formula 1

Example 1

Preparation of 4,4'-dimethylbiphenyl

10 g (79 mmol) of 4-chlorotoluene, 0.51 g (3.9 mmol) of nickel (II) chloride, 0.617 g (3.9 mmol) of 2,2'-bipyridine, 4.14 g (15.7 mmol) of triphenylphosphine, zinc ( 122.3 mmol) was added to a purified dimethylformamide solution and stirred at 90 ° C. for about 5 hours. After the reaction was completed, the reaction mixture was placed in a 1-normal aqueous hydrogen chloride solution to obtain a complex structure. After the reaction was extracted with methylene chloride, the solvent was removed under reduced pressure. The product was washed twice with methanol and then filtered under reduced pressure and dried: 75% yield.

¹ H-NMR (CDCl ₃ , ppm): 7.49 (d, 4H, Ar—H), 7.25 (d, 4H, Ar—H), 2.38 (s, 6H, —CH ₃ ).

IR (KBr, cm ⁻¹ ): 3040, 2900, 1500, 1110, 800.

MS (EI) (calculated for C ₁₄ H ₁₄ , 182.26; found, 182).

Example 2

Preparation of 4'-methylbiphenyl-4-carbaldehyde

2.4 g (13.3 mmol) of the compound (Compound 1) prepared in Example 1 and 0.536 g (3.0 mmol) of N-bromosuccinimide were added to a CCl ₄ solvent and refluxed for 24 hours. After the reaction was cooled, the solution obtained by vacuum filtration was washed with distilled water. After washing with distilled water and dried over anhydrous magnesium sulfate. The dried product was dissolved in chloroform again with 5.34 g (51.2 mmol) of hexamethylenetetraamine and refluxed for 5 hours. After cooling the reaction, the solvent was blown off under reduced pressure and vigorously refluxed at 120 ° C. for 2 h in acetic acid / H ₂ O (17 mL / 17 mL). Finally, 7 mL of HCl was added to reflux, the reaction was cooled, and extracted with methylene chloride. The solution was blown off under reduced pressure and then purified by column chromatography (silica gel, ethyl acetate / n-hexane = 1: 3) and dried: 24% yield.

¹ H-NMR (CDCl ₃ ): 10.0 (s, 1H, -CHO), 7.95 (d, 2H, Ar-H), 7.75 (d, 2H, Ar-H), 7.55 (d, 2H, Ar-H ), 7.28 (d, 2H, Ar-H), 2.42 (s, 3H, -CH ₃ ).

Example 3

Preparation of 1,3,5-tris (4-methyl-phenyl) -benzene

20 g (149.1 mmol) of 4-methylacetophenone was added to ethanol, and 17.08 mL (149.1 mmol) of SiCl ₄ was slowly added into a syringe and stirred at low temperature (5-10 ° C.). After stirring for 24 hours the product was filtered under reduced pressure. The filtered solid product was washed several times with ethanol and dried under vacuum: 82% yield.

¹ H-NMR (CDCl ₃ , ppm): 7.72 (s, 3H, Ar-H), 7.60 (d, 6H, Ar-H), 7.29 (d, 6H, Ar-H), 2.41 (s, 9H, -CH ₃ ).

IR (KBr, cm ⁻¹ ): 3010, 2950, 1600, 1500, 1410, 1390, 800.

MS (EI) (calc. For C ₂₇ H ₂₄ , 348.38; found, 348).

Example 4

Preparation of [1,3-bis (4-methyl-phenyl) -5- (4-cyanomethyl-phenyl)]-benzene

5 g (14.4 mmol) of the compound (Compound 4) prepared in Example 3 and 2.56 g (14.4 mmol) of N-bromosuccinimide were added to a CCl ₄ solvent and refluxed for 24 hours. After the reaction was cooled, the solution obtained by vacuum filtration was washed with distilled water. After washing with distilled water and dried over anhydrous magnesium sulfate. The solvent was removed under reduced pressure, and the obtained product was dissolved in THF again, and then poured into ethanol in which 2.35 g (48 mmol) of NaCN was dissolved, followed by stirring for 5 hours. After the reaction was completed, the solvent was blown out under reduced pressure, washed with water and extracted with methylene chloride. The solution was blown off under reduced pressure and then purified by column chromatography (silica gel, ethyl acetate / n-hexane = 1: 3) and dried: 39% yield (by compound, compound 5 obtained: 17% yield).

¹ H-NMR (CDCl ₃ , ppm): 7.76 (s, 1H, Ar-H), 7.72 (d, 4H, Ar-H), 7.60 (d, 4H, Ar-H), 7.45 (d, 2H, Ar-H), 7.30 (d, 4H, Ar-H), 3.81 (s, 2H, -CH ₂ CN), 2.46 (s, 6H, (-CH ₃ ) ₂ ).

IR (KBr, cm ⁻¹ ): 3010, 2950, 2250, 1600, 1500, 1410, 800.

MS (EI) (calculated for C ₂₈ H ₂₃ N, 373.49; found, 373).

Example 5

Preparation of [1,3-bis- (4-methyl-phenyl) -5- (4-formyl) -phenyl] -benzene

4.67 g (13.4 mmol) of Compound 4 and 3.58 g (20.0 mmol) of N-bromosuccinimide were added to a CCl ₄ solvent and refluxed for 24 hours. After the reaction was cooled, the solution obtained by vacuum filtration was washed with distilled water. After washing with distilled water and dried over anhydrous magnesium sulfate. The solvent was removed under reduced pressure, and then purified by column chromatography (silica gel, ethyl acetate / n-hexane = 1: 5) and dried. The dried product was dissolved in chloroform again with 4.4 g (42.7 mmol) of hexamethylenetetraamine and refluxed for 5 hours. After cooling the reaction, the solvent was blown off under reduced pressure and vigorously refluxed at 120 ° C. for 2 h in acetic acid / H ₂ O (25 mL / 25 mL). Finally, 10 mL of HCl was added to reflux, the reaction was cooled, and extracted with methylene chloride. The solution was blown off under reduced pressure and then purified by column chromatography (silica gel, ethyl acetate / n-hexane = 1: 3) and dried: 17% yield.

¹ H-NMR (CDCl ₃ , ppm): 10.0 (s, 1H, -CHO), 8.0 (d, 2H, Ar-H), 7.87-7.77 (m, 5H, Ar-H), 7.60 (d, 4H , Ar-H), 7.28 (d, 4H, Ar-H), 2.42 (s, 6H, (-CH ₃ ) ₂ ).

Example 6

Preparation of Biphenyl-4,4'-Dicarbaldehyde

2.5 g (13.7 mmol) of Compound 1 and 6.1 g (34.3 mmol) of N-bromosuccinimide were added to a CCl ₄ solvent and refluxed for 24 hours. After the reaction was cooled, the solution obtained by vacuum filtration was washed with distilled water. After washing with distilled water and dried over anhydrous magnesium sulfate. The dried product was dissolved in chloroform again with 6.6 g (47.1 mmol) of hexamethylenetetraamine and refluxed for 5 hours. After cooling the reaction, the solvent was blown off under reduced pressure and vigorously refluxed at 120 ° C. for 2 h in acetic acid / H ₂ O (17 mL / 17 mL). Finally, 7 mL of HCl was added to reflux, the reaction was cooled, and extracted with methylene chloride. The solution was blown off under reduced pressure and then purified by column chromatography (silica gel, ethyl acetate / n-hexane = 1: 3) and dried: 69% yield.

¹ H-NMR (CDCl ₃ ): 10.1 (s, 2H, -CHO), 7.99 (d, 4H, Ar-H), 7.79 (d, 4H, Ar-H).

Example 7

Preparation of 4,4'-Dimethyl-Stilbene

2.4 g (5.37 mmol) of (4-methylbenzyl) triphenylphosphonium bromide and 0.98 g (60%, 24.4 mmol) of NaH are refluxed in toluene for 6 hours. After the temperature was reduced, 0.586 g (4.88 mmol) of 4-methylbenzaldehyde was slowly added thereto. Then reflux for 6 hours. The product obtained is treated with water and extracted with ethyl acetate. Blow off the solvent and recrystallize in ethanol: 71% yield.

¹ H-NMR (CDCl ₃ ): 7.64 (d, 4H, Ar-H), 7.16 (d, 4H, Ar-H), 6.90 (s, 2H, vinyl).

Example 8

Preparation of 4,4'-diformyl-steelbene

2 g (9.6 mmol) of the compound (Compound 9) prepared in Example 7 and 4.27 g (24.0 mmol) of N-bromosuccinimide were added to a CCl ₄ solvent and refluxed for 24 hours. After the reaction was cooled, the solution obtained by vacuum filtration was washed with distilled water. After washing with distilled water and dried over anhydrous magnesium sulfate. The dried product was dissolved in chloroform again with 4.0 g (38.4 mmol) of hexamethylenetetraamine and refluxed for 5 hours. After cooling the reaction, the solvent was blown off under reduced pressure and vigorously refluxed at 120 ° C. for 2 h in acetic acid / H ₂ O (17 mL / 17 mL). Finally, 7 mL of HCl was added to reflux, the reaction was cooled, and extracted with methylene chloride. The solution was blown off under reduced pressure and then purified by column chromatography (silica gel, ethyl acetate / n-hexane = 1: 1) and dried: 20% yield.

¹ H-NMR (CDCl ₃ ): 10.03 (s, 2H), 7.92 (d, 4H, Ar-H), 7.71 (d, 4H, Ar-H), 7.30 (s, 2H, vinyl).

EXAMPLES 9-13

Preparation of Branched α-Cyanostilbene Derivatives of Formula 1

Example 9

Preparation of 2,3-bis- [3,5- (4-methyl-phenyl) -biphenyl-4-yl] -acrylonitrile (Model 1)

0.31 g (0.8 mmol) of the compound (Compound 5) prepared in Example 4 and 0.2 g (0.8 mmol) of the compound (Compound 6) prepared in Example 5 were added to a tert-butyl alcohol and purified THF solvent at 50 ° C. After dissolving, 0.08 mL of tetrabutylammonium hydroxide (1M solution in methanol) was slowly added thereto. Stir at 50 ° C. for 20 minutes. The product, which had fallen to precipitate, was dried by filtration under reduced pressure: 93% yield.

¹ H-NMR (CDCl ₃ , ppm): 8.06 (d, 2H, Ar-H), 7.80 (m, 12H, Ar-H), 7.66 (s, 1H, vinyl proton), 7.62 (d, 8H, Ar -H), 7.32 (d, 8H, Ar-H), 2.43 (s, 12H, -CH ₃ ).

IR (KBr, cm ⁻¹ ): 3040, 2950, 2230, 1600, 1510, 800.

MS (EI) (calculated for C ₅₅ H ₄₃ N, 717.94; found, 718).

Example 10

Manufacturing of Model 2

Knoevenagel synthesis was used as Model 1: 74% yield.

¹ H-NMR (CDCl ₃ , ppm): 8.06 (s, 4H, Ar-H), 7.80 (m, 14H, Ar-H), 7.64 (m, 10H, Ar-H), 7.30 (d, 8H, Ar-H), 2.43 (s, 12H, -CH ₃ ).

IR (KBr, cm ⁻¹ ): 3040, 2950, 2222, 1600, 1500, 1280, 800, 750.

MS (EI) (calculated for C ₅₅ H ₄₃ N, 845.08; found, 845).

Example 11

Manufacturing of Model 3

Knoevenagel synthesis was used as Model 1: 97% yield.

¹ H-NMR (CDCl ₃ , ppm): 8.06 (d, 4H, Ar-H), 7.85 (m, 18H, Ar-H), 7.66 (m, 10H, Ar-H), 7.62 (d, 8H, Ar-H), 2.43 (s, 12H, -CH ₃ ).

IR (KBr, cm ⁻¹ ): 3040, 2950, 2222, 1600, 1500, 1280, 810, 750.

MS (EI) (calculated for C ₅₅ H ₄₃ N, 921.18; found, 921).

Example 12

Manufacturing of Model 4

Knoevenagel synthesis was used as Model 1: 83% yield.

¹ H-NMR (CDCl ₃ , ppm): 8.10 (s, 1H, Ar-H), 7.96 (s, 1H, Ar-H), 7.80 (m, 14H, Ar-H), 7.62 (m, 10H, Ar-H), 7.26 (d, 8H, Ar-H), 4.00 (s, 6H, -OCH ₃ ), 2.43 (s, 12H, -CH ₃ ).

IR (KBr, cm ⁻¹ ): 3040, 2950, 2220, 1600, 1510, 1230, 800, 750.

MS (EI) (calculated for C ₅₅ H ₄₃ N, 905.13; found, 905).

Example 13

Manufacturing of Model 5

Knoevenagel synthesis was used as Model 1: 93% yield.

¹ H-NMR (CDCl ₃ , ppm): 7.98 (d, 4H, Ar-H), 7.78 (m, 14H, Ar-H), 7.62 (m, 15H, Ar-H), 7.32 (d, 9H, Ar-H), 2.43 (s, 12H, -CH ₃ ).

IR (KBr, cm ⁻¹ ): 3040, 2950, 2222, 1600, 1500, 1380, 800, 750.

MS (EI) (calculated for C ₅₅ H ₄₃ N, 947.21; found, 947).

The branched α-cyanostilbene-based emitters of the novel structure of the general formula (1) according to the present invention can be said to be an organic electroluminescent material which is very useful for the production of organic EL devices exhibiting luminescent properties in both powder, solution and film phases.

In particular, by changing the core structure such as the substituent R _{1 it} is possible to manufacture a high-efficiency display device capable of full-color display as the first material that can control the color of red, green, blue.

In addition, all of the above materials exhibit excellent thermal stability, and thus exhibit excellent stability in the manufacturing process of the organic EL device.

Claims (3)

Α-cyanostilbene compound of Formula 1 [Formula 1] [In the meal, R ₂ and R ₃ represent a C1-C6 alkyl group, a C1-C6 alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, and a substituted or unsubstituted aryl group or substituted Or an unsubstituted heterocyclic group can be condensed at any position of the corresponding benzene ring and benzene ring. An organic electroluminescent composition comprising an α-cyanostilbene compound of Formula 1 below: [Formula 1] [In the meal, R ₂ and R ₃ represent a C1-C6 alkyl group, a C1-C6 alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, and a substituted or unsubstituted aryl group or substituted Or an unsubstituted heterocyclic group can be condensed at any position of the corresponding benzene ring and benzene ring. A powder, an organic solution, and a film having a α-cyanostilbene-based compound of Formula 1 [Formula 1] [In the meal, R ₂ and R ₃ represent a C1-C6 alkyl group, a C1-C6 alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group, and a substituted or unsubstituted aryl group or substituted Or an unsubstituted heterocyclic group can be condensed at any position of the corresponding benzene ring and benzene ring.