CN107698584B - Blue light material for organic light-emitting diode and synthetic method thereof - Google Patents

Abstract

The invention discloses a blue light material for an organic light-emitting diode and a preparation method thereof, wherein the blue light material has a specific structure and is obtained by carrying out reflux reaction on a compound with the specific structure under the condition that an anhydride compound is used as a solvent. The invention is realized by changing R₁And R₂The kind of the group can adjust the physical and chemical properties of the material, and the change of the group can adjust the processing property, the thermal property, the spectral property and the like, such as increasing R₁And R₂The chain length of the group can increase the solubility of the material and change R₁And R₂The electron donating property of the group can adjust the band gap of the material and further influence the light-emitting wavelength range of the material. The blue light material has good luminous performance, high luminous efficiency and good stability, and the synthesis method has simple and easily realized process and low cost, and has practicability in the field of organic electroluminescent display.

Description

A kind of blue light material for organic light emitting diode and its synthesis method

technical field

The invention relates to the field of organic materials, in particular to a blue light material for organic light-emitting diodes and a synthesis method thereof.

Background technique

Organic Light Emitting Diode (OLED) is a new type of high-performance display technology. It has the characteristics of high color gamut, low energy consumption, wide viewing angle, easy bending, and self-illumination. It is considered to be the mainstream technology of next-generation display. Due to its broad application prospects in the field of information display, OLED has received extensive attention from academia and industry. In recent years, various display technology powerhouses (such as South Korea, Japan, China, etc.) have continued to increase their investment in OLED display technology, indicating that the market has high expectations for OLED display technology.

The high-quality presentation of red, green, and blue primary colors is an essential condition for full-color OLED display technology, and it is also its main feature. At present, in the field of OLED display technology, there is no technical problem in realizing high-performance red and green light emission. In contrast, blue OLEDs with high luminous efficiency and good device stability are difficult to achieve, mainly due to the unsatisfactory properties of blue organic light-emitting materials. On the one hand, blue light emission requires materials with wider band gaps than red and green light materials, which makes their synthesis and purification difficult. On the other hand, the blue light material has poor matching degree with other auxiliary materials (such as hole injection layer materials, etc.) in the device, resulting in poor luminous efficiency and stability. Therefore, optimizing organic blue light molecules from the perspective of material design and synthesis is of great significance for the realization of full-color OLED display technology.

SUMMARY OF THE INVENTION

In order to solve the problems in the prior art, the present invention provides a blue light material for organic light emitting diodes and a method for synthesizing the same. The blue light material prepared by the method has a narrow band gap, high luminous efficiency and good stability. The method is simple, easy to implement, and low in cost. The technical solution is as follows:

A blue light material for organic light-emitting diodes, characterized in that:

The chemical structure of the material is shown in formula (1):

Wherein, the R ₁ and R ₂ are each independently selected from any one of the following: H, halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, heteroalkyl, cycloalkyl, ring alkenyl, heterocycloalkyl, heterocycloalkenyl, aryl, heteroaryl, cycloalkylalkyl, heterocycloalkylalkyl, arylalkyl, heteroarylalkyl, arylalkenyl, ring alkylheteroalkyl, heterocycloalkylheteroalkyl, heteroarylheteroalkyl, arylheteroalkyl, hydroxy, hydroxyalkyl, alkoxy, alkoxyalkyl, alkoxyaryl, alkene Oxy, alkynyloxy, cycloalkyloxy, heterocycloalkyloxy, aryloxy, arylalkoxy, phenoxy, benzyloxy, heteroaryloxy, amino, alkylamino, Aminoalkyl, acylamino, arylamino, sulfonylamino, sulfinylamino, alkoxycarbonyl, alkylaminocarbonyl, sulfonyl, alkylsulfonyl, alkylsulfinyl, arylsulfonyl, aryl sulfinyl, aminosulfonyl or acyl.

Preferably, the R ₁ is H, halogen or a C ₁ -C ₁₅ aryl group, and R ₂ is a C ₁ -C ₁₅ alkyl group or a C ₁ -C ₁₅ aryl group. More preferably, said R ₁ is H, halogen or aryl, and R ₂ is alkyl or aryl. Most preferably, the R ₁ is Br, H or a benzene ring, and the R ₂ is CH ₃ or a benzene ring.

Another object of the present invention is to provide a method for preparing the above-mentioned blue light material for organic light emitting diodes. Backflow reaction, the blue light material is obtained after the reaction is completed;

After the reflux reaction is detected by TLC (thin layer chromatography plate), after the reaction is complete, the acid anhydride whose structure is shown in formula (3) is removed and the blue light material is obtained by separation and purification by silica gel column chromatography. The purification conditions can be determined by those skilled in the art. It is determined by experiments that the preferred mobile phase volume ratio of the present invention is V (petroleum ether): V (ethyl acetate)=1: (1-10).

Preferably, the compound represented by the structural formula (2) is obtained by mixing the compound represented by the structural formula (4), the compound represented by the structural formula (5), malononitrile and a catalyst in a solvent, Obtained after carrying out ring-closure reaction at reflux temperature;

After the ring closure reaction is detected by TLC (thin layer chromatography plate), the reaction is completed, extracted with dichloromethane, and then separated and purified by silica gel column chromatography to obtain a compound whose structure is shown in formula (2). The purification conditions can be determined by those skilled in the art. Personnel have determined through experiments that the preferred volume ratio of the mobile phase in the present invention is V (dichloromethane): V (ethyl acetate)=(100-5):1.

As known to those skilled in the art, in the case where the R ₁ group is an aryl group, in order to prevent the ring-closure reaction from occurring at an undesired reaction site, it is preferable to perform the above-mentioned ring-closure reaction with p-bromobenzaldehyde as a raw material first. , and then introduce an aryl group through the Suzuki coupling reaction to obtain the target product.

More preferably, the molar ratio of the compound whose structure is shown in formula (4), the compound whose structure is shown in formula (5) and malononitrile added in the ring closing reaction is 1:(1～1.5):( 1 to 1.5).

The solvent in the ring-closing reaction is preferably water, and other solvents can also be used under the condition of ensuring the solubility of the reaction substrate.

More preferably, when the ring-closure reaction solvent is water, the reflux temperature in the ring-closure reaction is 90-100°C.

Preferably, the catalyst in the ring closure reaction is L-proline. The amount of the catalyst to be added is determined according to the amount of the catalyst conventionally used by those skilled in the art. In the present invention, it is preferred to add 0.5-0.1 molar equivalent of the compound represented by the formula (4).

The synthetic route of the synthetic blue light material of the present invention is shown in formula (6):

The blue light material of the invention has good luminescence performance, the peak range of photoluminescence and electroluminescence spectrum is 440-485nm, the CIE range of photoluminescence and electroluminescence color coordinates is (0.14-0.19, 0.04-0.19), The quantum yield of luminescence and electroluminescence ranges from 20% to 100%; and the blue light material of the present invention has excellent solubility, and can be used in common solvents (such as chloroform, toluene, xylene, chlorobenzene, dichlorobenzene, tetrahydrofuran, etc.) The solubility in all of them is greater than 5mg/mL.

The beneficial effects brought by the technical scheme provided by the invention are:

The present invention takes 4-imino-7-methyl-2-phenyl-4H-pyrido[1,2-a]pyrimidine-3-carbonitrile as the main body, and is introduced into the imino position and the 2-phenyl para position respectively. R ₂ and R ₁ groups, and finally obtain the target blue light material. The present invention adjusts the physical and chemical properties of the material by changing the types of R ₁ and R ₂ groups, and changes the groups to adjust its processing performance, thermal properties and spectral properties. For example, increasing the chain length of the R ₁ and R ₂ groups can increase the material. The solubility of R ₁ and R ₂ groups can be adjusted by changing the electron-donating and donating properties of the R 1 and R 2 groups to adjust the band gap of the material and then affect the emission wavelength range of the material. The blue light material of the invention has good light-emitting performance, high light-emitting efficiency, good stability, simple and easy-to-implement synthesis method and low cost, and has practicability in the field of organic electroluminescence display.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

Fig. 1 is the NMR spectrum of blue light material A;

Fig. 2 is the hydrogen nuclear magnetic spectrum of blue material B;

Fig. 3 is the absorption spectrum and photoluminescence spectrum of blue material B;

Fig. 4 is the hydrogen nuclear magnetic spectrum of blue material C;

FIG. 5 is a hydrogen NMR spectrum of blue material D. FIG.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments.

Example 1:

In a 250mL round-bottomed flask, first add 0.5-0.1e.q. of L-proline (preferably 230mg, 0.2mmol) and 1.0-1.5e.q. of malononitrile (preferably 793mg, 12mmol) to dissolve completely, then add 1.0e.q. Benzaldehyde (preferably 1.06g, 10mmol), 1.0～1.2e.q. of 2-amino-5-methylpyridine (preferably 1.296g, 12mmol) were placed in a 90°C oil bath to react, TLC (thin layer chromatography) ) was detected until the reaction was complete for about 8h. Carry out post-treatment and purification: add dichloromethane (20 mL×3) for extraction, wash with saturated NaCl solution (20 mL×1), separate the organic phases and combine the organic phases, add anhydrous sodium sulfate to dry. Remove the solvent, separate and purify by silica gel column chromatography, V(petroleum ether):V(ethyl acetate) ranges from 10:1 to 1:1, preferably, V(petroleum ether):V(ethyl acetate)=3 : 1, a pure yellow powder was obtained.

Compound I-1 was tested by H NMR:

¹ H NMR (400 MHz, CDCl ₃ ) δ 9.18 (s, 1H), 7.96 (dd, J=6.5, 3.0 Hz, 2H), 7.71 (dd, J=9.0, 2.0 Hz, 1H), 7.56 (s, 1H), 7.51(dd, J=5.1, 1.7Hz, 3H), 2.45(s, 3H).

Example 2:

In a 50 mL round-bottomed flask, compound I-1 (970 mg, 3.73 mmol) and 15 mL of acetic anhydride were added, heated to 150° C. to react, and TLC (thin-layer chromatography) detected that the reaction was complete for about 3.5 h. Carry out post-treatment and purification: remove acetic anhydride, separate and purify with silica gel column chromatography, the range of V (petroleum ether): V (ethyl acetate) is 1:1 to 1:10, in this embodiment, the preferred [V (petroleum ether) ): V(ethyl acetate)=1:10] to obtain a yellow powder.

The hydrogen NMR spectrum of the compound blue material A is shown in Figure 1:

¹ H NMR (400 MHz, CDCl ₃ ) δ 9.09 (s, 1H), 7.99 (d, J=7.1 Hz, 2H), 7.85 (dd, J=8.9, 1.6 Hz, 1H), 7.73 (d, J= 8.9Hz, 1H), 7.60-7.42(m, 3H), 7.26(s, 1H), 2.47(d, J=35.9Hz, 6H).

Example 3:

In a 250mL round-bottomed flask, first add 0.05-0.3e.q. of L-proline (preferably 230.6mg, 2.0mmol) and 1.0-1.5e.q. of malononitrile (preferably 7-93.2mg, 12mmol) to dissolve completely, then add 1.0e.q of 4-bromo-benzaldehyde (1.85g, 10mmol), 1.0～1.5e.q. of 2-amino-5-methylpyridine (preferably 1.296g, 12mmol), placed in a 90°C oil bath to react, TLC ( Thin-layer chromatography) detected until the reaction was complete about 8h. Carry out post-treatment and purification: add dichloromethane (20 mL×3) for extraction, wash with saturated NaCl solution (20 mL×1), separate the organic phases and combine the organic phases, add anhydrous sodium sulfate to dry. The solvent was removed and purified by silica gel column chromatography. The range of V(dichloromethane):V(ethyl acetate) was 100:1 to 5:1, preferably, V(dichloromethane):V(ethyl acetate) = 30:1 to obtain yellow powder.

Compound II-1 was tested by H NMR:

1H NMR(400MHz, CDCl3)δ9.23(s,1H),7.86(d,J=7.9Hz,2H),7.74(d,J=8.9Hz,1H),7.64(d,J=7.7Hz,2H) ), 7.55(d, J=8.9Hz, 1H), 2.46(s, 3H).

Example 4:

In a 50 mL two-necked flask, 1 mL of water, 20 mL of 1,4-dioxane, 1.0 eq of compound II-1 (507 mg, 1.5 mmol), and 2.0 to 5.0 eq of potassium carbonate (preferably 795 mg) were added under nitrogen. , 5.75mmol) through N ₂ to remove oxygen, then add 2.0～5.0eq phenylboronic acid (preferably 549mg, 4.5mmol), 0.01～0.5eq tetrakis(triphenylphosphine)palladium (preferably 69.3mg, 0.006mmol), heat to 125°C, TLC (thin layer chromatography) detected that the reaction was complete for about 48h. Carry out post-treatment purification: remove the solvent, separate and purify with silica gel column chromatography, the range of V (dichloromethane): V (ethyl acetate) is 300:1 to 1:0, in this embodiment, pure dichloromethane is preferred, A yellow-green powder was obtained.

Compound II-2 was detected by H NMR:

1H NMR(400MHz, CDCl3)δ9.29(s,1H),8.09(d,J=8.1Hz,2H),7.74(d,J=8.0Hz,3H),7.65(d,J=7.9Hz,2H) ), 7.61(s, 1H), 7.48(t, J=7.5Hz, 2H), 7.40(d, J=7.0Hz, 1H), 2.47(s, 3H).

Example 5:

In a 50 mL round-bottomed flask, compound II-2 (200 mg, 0.6 mmol) and 15 mL of acetic anhydride were added, heated to 150° C. to react, and TLC (thin layer chromatography) detected the reaction to complete for about 3.5 hours. Carry out post-treatment purification: remove acetic anhydride, separate and purify with silica gel column chromatography, the range of V (dichloromethane): V (ethyl acetate) is 50: 1 to 3: 1, in this embodiment, [V (dichloromethane) is preferred. Chloromethane):V(ethyl acetate)=10:1] to give a yellow powder.

The hydrogen NMR spectrum of the compound blue material B is shown in Figure 2:

1H NMR (400MHz, CDCl3) δ 9.09 (s, 1H), 8.10 (d, J=8.3Hz, 2H), 7.86 (dd, J=8.9, 1.7Hz, 1H), 7.74 (d, J=8.5Hz) ,3H),7.65(d,J＝7.8Hz,2H),7.48(t,J＝7.6Hz,2H),7.41(d,J＝7.6Hz,1H),2.52(s,3H),2.44(s , 3H).

The absorption spectrum and photoluminescence spectrum of blue material B are shown in Figure 3. It can be seen from the figure that the emission peak of molecule B is around 460 nm, and its main emission peak covers the blue emission region of 400-500 nm, indicating that Molecule B is a good blue light emitting material.

Example 6:

In a 50 mL round-bottomed flask, compound II-1 (338 mg, 1.0 mmol) and 20 mL of acetic anhydride were added, heated to 150° C. to react, and TLC (thin layer chromatography) detected the reaction until the reaction was complete for about 3.5 h. Carry out post-treatment purification: remove acetic anhydride, separate and purify with silica gel column chromatography, the range of V (dichloromethane): V (ethyl acetate) is 50: 1 to 3: 1, in this embodiment, [V (dichloromethane) is preferred. Chloromethane):V(ethyl acetate)=10:1] to give a yellow powder.

The hydrogen NMR spectrum of the compound blue material C is shown in Figure 4:

¹ H NMR (400 MHz, CDCl ₃ ) δ 9.08 (s, 1H), 7.87 (dd, J=11.7, 5.1 Hz, 3H), 7.72 (d, J=8.9 Hz, 1H), 7.65 (d, J= 8.5Hz, 2H), 2.52(s, 3H), 2.42(s, 3H).

Example 7:

In a 50mL round-bottomed flask, add compound II-1 (85mg, 0.25mmol), 3-10e.q. benzoic anhydride preferably (282mg, 1.25mmol), 10mL acetonitrile, heat to 120°C for reaction, TLC (thin layer) Chromatography) detected until the reaction was complete about 8h. Carry out post-treatment purification: remove acetonitrile, separate and purify with silica gel column chromatography, the range of V (dichloromethane): V (ethyl acetate) is 50: 1 to 2: 1, in this embodiment [V (dichloromethane) is preferred methane):V(ethyl acetate)=8:1] to give a yellow powder.

The hydrogen NMR spectrum of the compound blue material D is shown in Figure 5:

¹ H NMR (400 MHz, CDCl ₃ ) δ 9.09 (s, 1H), 8.10 (d, J=8.3 Hz, 2H), 7.86 (dd, J=8.9, 1.7 Hz, 1H), 7.74 (d, J= 8.5Hz, 3H), 7.65 (d, J=7.8Hz, 2H), 7.48 (t, J=7.6Hz, 2H), 7.41 (d, J=7.6Hz, 1H), 2.52 (s, 3H), 2.44 (s, 3H).

It should be noted that the blue light materials provided in the above-mentioned embodiments only take the synthesis method of some blue light molecules as an example to illustrate the distance. In practical applications, different R ₁ and R ₂ groups can be designed as required to obtain different solubility. The blue light material and the specific required emission wavelength range are adjusted, and the specific preparation method thereof is detailed in the method embodiment, which will not be repeated here.

The above-mentioned serial numbers of the embodiments of the present invention are only for description, and do not represent the advantages or disadvantages of the embodiments.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (6)

1. A blue light emitting material for an organic light emitting diode, comprising:

the chemical structure of the blue light material is shown as formula (1):

wherein, R is₁Is H, halogen or C₆-C₁₅Aryl of (A), R₂Is C₁-C₁₅Alkyl or C₆-C₁₅Aryl group of (1).

2. The blue light emitting material for organic light emitting diode according to claim 1, wherein: the R is₁Is Br, H or a benzene ring, the R₂Is CH₃Or a benzene ring.

3. A method for preparing a blue light emitting material for an organic light emitting diode according to claim 1, wherein: carrying out reflux reaction on a compound with a structure shown as a formula (2) under the condition that anhydride with a structure shown as a formula (3) is used as a solvent, and obtaining the blue light material after the reaction is finished;

wherein, in R₁Under the condition that the group is not aryl, the compound with the structural formula shown in (2) is obtained by performing a cyclization reaction on a mixture of a compound with the structural formula shown in (4), a compound with the structural formula shown in (5), malononitrile and a catalyst in a solvent at a reflux temperature;

at R₁In the case of aryl radical, p-bromobenzaldehyde is used as the first stepThe raw materials are a compound with a structure shown in a formula (5), malononitrile and a mixture of a catalyst in a solvent, the compound, the malononitrile and the catalyst are subjected to a cyclization reaction at a reflux temperature, and then an aryl group is introduced through a Suzuki coupling reaction to obtain the compound with a structural formula shown in a formula (2).

4. The method for preparing a blue light emitting material for an organic light emitting diode according to claim 3, wherein: the mole ratio of the compound with the structure shown in the formula (4) and the compound with the structure shown in the formula (5) to the malononitrile added in the cyclization reaction is 1: (1-1.5): (1-1.5).

5. The method for preparing a blue light emitting material for an organic light emitting diode according to claim 3, wherein: the solvent in the cyclization reaction is water.

6. The method for preparing blue light emitting material for organic light emitting diode as claimed in claim 3, wherein the catalyst in said ring closing reaction is L-proline.

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