Organic electroluminescent material based on pyrazine derivative and preparation method and application thereof

Abstract

The invention discloses an organic electroluminescent material based on pyrazine derivatives and a preparation method and application thereof, and belongs to the technical field of electroluminescent materials, and the preparation method comprises the following steps: mixing a diamine compound and a diketone compound for reaction to obtain an intermediate, mixing the obtained intermediate with diphenylamine for coupling reaction to obtain the organic electroluminescent material based on pyrazine derivatives. The organic electroluminescent material based on the pyrazine derivative is obtained. The invention also discloses the electroluminescent material prepared by the preparation method and an application of the electroluminescent material in an electroluminescent device. The AIE characteristic is combined in a single molecule, the acid-induced discoloration property is achieved, the acid-induced discoloration property is utilized, and the acid-induced discoloration-based fluorescent material can be applied to the field of fluorescent falsification prevention and has huge application potential in the aspects of displayers, lighting technologies and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of electroluminescent materials, and in particular relates to an organic electroluminescent material based on pyrazine derivatives and a preparation method and application thereof. Background Art

[0002] Organic light-emitting diodes are becoming increasingly popular in display or phototherapy lighting applications due to their advantages such as high-quality color, low energy cost, light weight and flexibility. However, there are some challenges before OLEDs can be truly applied in large displays such as TVs, mainly including color purity, stability and limited external quantum efficiency (EQE) in the solid state. Currently, commercial emission materials used in OLED displays are generally phosphorescent materials, such as iridium and platinum complexes, which can fully collect singlet (25%) and triplet (75%) excitons, potentially providing an internal quantum efficiency close to 100%. However, these phosphorescent materials require the use of expensive rare precious metals, which increases the manufacturing cost. Organic small molecule fluorophores based on donor-acceptor (DA) molecular structures are one of the candidates for the preparation of high-efficiency OLEDs due to their simple structure, good reproducibility, easy purification, and balanced charge transport properties.

[0003] The molecular arrangement of fluorescent molecules in the solid state has a significant impact on their photoluminescence quantum yield (PLQY) and the EQE of the device. Due to the inherent nature of the aggregation of molecules when building thin films, quenching effects usually occur through aggregation-induced quenching (ACQ). In recent years, there has been increasing interest in emitters with aggregation-induced emission (AIE) properties, which are weakly fluorescent in organic solutions but become strong emitters with excellent efficiency when prepared as solid films. AIE emitters are suitable for manufacturing devices with better aggregation-induced quenching (ACQ) performance than ordinary emitters, significantly reducing manufacturing complexity and thus improving yield.

[0004] So far, more and more AIE materials exhibiting mechanochromic properties have been developed and applied in various fields, including pressure sensors, information security and storage, optoelectronic devices, and wearable systems. However, current mechanochromic materials with AIE properties still have disadvantages such as complex operation or prolonged switching time, which hinders practical applications.

[0005] Therefore, how to provide a mechanical color-changing material with AIE characteristics that is simple to operate and highly efficient is a technical problem that those skilled in the art need to solve urgently. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes an organic electroluminescent material based on pyrazine derivatives and a preparation method and application thereof.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing an organic electroluminescent material based on a pyrazine derivative comprises the following steps:

[0009] The diamine compound and the diketone compound are mixed and reacted to obtain an intermediate, and the intermediate is then mixed with diphenylamine for a coupling reaction to obtain the organic electroluminescent material based on the pyrazine derivative.

[0010] Preferably, the diamine compound and the diketone compound are reacted in an organic solution.

[0011] Preferably, the organic solution comprises ethanol solution and / or acetic acid solution.

[0012] Preferably, the molar ratio of the diamine compound to the diketone compound is 1:1.

[0013] The present invention is carried out through a ring condensation reaction to generate a condensation product containing a pyrazine ring under acidic conditions.

[0014] Preferably, the diamine compound is pyridine-3,4-diamine.

[0015] Preferably, the diketone compound is 1,2-bis(4-bromophenyl)ethane-1,2-dione or 3,6-dibromophenanthrene-9,10-dione.

[0016] Beneficial effect: The reaction equation for the preparation of the intermediate is as follows:

[0017]

[0018] Preferably, the temperature of the mixed reaction is 90° C., the time is 10 h, and the atmosphere is an oxygen-free atmosphere.

[0019] Preferably, the molar ratio of the intermediate to diphenylamine is 1:2.3.

[0020] Preferably, the coupling reaction is a Buchwald-Hartwig coupling reaction, the coupling reaction temperature is 110° C., the time is 24 h, and the atmosphere is an oxygen-free atmosphere.

[0021] Preferably, the intermediate is subjected to a coupling reaction with diphenylamine in a toluene solution in the presence of a catalyst;

[0022] The catalyst includes Pd 2 (dpa) 3 , Cs 2 CO 3 and (t-Bu) 3 P.HBF 4 .

[0023] Beneficial effects: The reaction mechanism of the above coupling reaction is as follows:

[0024] (1) Oxidative addition: First, the active zero-valent palladium species [Pd] is generated by activation. 0 It undergoes oxidative addition reaction with the CX bond (X is a halogen) to form a divalent palladium complex.

[0025] (2) Amine affinity addition: Next, the amine undergoes ligand exchange with the divalent palladium complex to form an intermediate.

[0026] (3) Deprotonation: The intermediate is deprotonated by a strong base to generate another intermediate.

[0027] (4) Reductive elimination: Finally, this intermediate undergoes reductive elimination to generate the target compound, i.e., the N-arylation product of the amine. At the same time, the zero-valent palladium is recycled and enters the next catalytic cycle.

[0028] The reaction equation for the above reaction is as follows:

[0029]

[0030] The organic electroluminescent material based on pyrazine derivatives is prepared by the above-mentioned preparation method.

[0031] Preferably, the structural formula of the electroluminescent material is:

[0032]

[0033] Beneficial effects: In the organic fluorescent molecules t-BuDPAiPP and t-BuDPAPQ designed by the present invention, a donor-acceptor-donor structure (DAD) is formed by connecting pyrazine derivatives (iPP and PQ) and t-BuDPA. The iPP and PQ motifs have good electron-withdrawing ability, which may help to obtain a smaller singlet-triplet energy gap (ΔEST) and promote intersystem reverse crossing (RISC). Nitrogen atoms can promote spin-orbit coupling (SOC), thereby further enhancing the RISC process. In addition, PQ has both rigidity and planarity, which can promote favorable π-electron flow and high PLQY. Diphenylamine can promote the AIE effect through spatial conformational distortion. The electroluminescent material provided by the present invention is processed by solution, and is doped with the host material as a luminescent material (guest material) to prepare a light-emitting layer. It can be applied to a single-light-emitting layer organic small molecule electroluminescent device and has good conversion efficiency.

[0034] As mentioned above, the organic electroluminescent materials based on pyrazine derivatives are used in the field of fluorescent anti-counterfeiting.

[0035] Application of the above-mentioned organic electroluminescent material based on pyrazine derivatives in electroluminescent devices.

[0036] An electroluminescent device comprises a light-emitting layer, wherein the light-emitting layer comprises the above-mentioned organic electroluminescent material.

[0037] Preferably, the mass fraction of the electroluminescent material in the light-emitting layer of the electroluminescent device is 3-15%.

[0038] More preferably, the light-emitting layer is prepared by mixing an electroluminescent material with a host material.

[0039] More preferably, the main material is PhCzBCz.

[0040] Compared with the prior art, the present invention has the following advantages and technical effects:

[0041] The organic electroluminescent material based on pyrazine derivatives provided by the present invention has aggregation-induced (AIE) properties and acid-induced color properties, and the structure is a DAD-type molecule, in which the restricted rotation of the acceptor around the donor contributes to the performance of the AIE effect, and the band gap energy is increased by increasing the transition energy between the molecular ground state and the excited state. The electroluminescent material provided by the present invention not only exhibits excellent AIE characteristics, but also exhibits acid-induced color properties. At the same time, the present invention combines the AIE characteristics in a single molecule and has acid-induced color properties. By utilizing the acid-induced color properties, it can be applied to the field of fluorescent anti-counterfeiting, and has great application potential in display, lighting technology, etc. In addition, the organic electroluminescent device prepared by the present invention using the organic small molecule electroluminescent material exhibits good performance, specifically, the organic light-emitting device (OLEDs) prepared with t-BuDPAiPP and t-BuDPAPQ achieves maximum EQEs of 1.5% and 0.77%, respectively, and the emission peaks are at 546 and 595nm. The organic small molecule electroluminescent material of the present invention has a good application value in the development field of multifunctional orange electroluminescent materials. Finally, the preparation method of the present invention is simple and the reaction conditions are mild, which is conducive to the promotion of production and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0043] Figure 1 The UV-visible absorption spectra of the products of Example 1-2 in different solutions;

[0044] Wherein, (a) is Example 1, and (b) is Example 2;

[0045] Figure 2 The fluorescence emission spectra of the product of Example 1-2 in different solutions;

[0046] Wherein, (a) is Example 1, and (b) is Example 2;

[0047] Figure 3 The fluorescence emission spectra of the product of Example 1-2 in methanol / water mixtures with different water volume fractions;

[0048] Wherein, (a) is Example 1, and (b) is Example 2;

[0049] Figure 4 This is a simulation diagram of the effect of the product of Example 1-2 in the field of fluorescent anti-counterfeiting;

[0050] Wherein, (a) is Example 1, and (b) is Example 2;

[0051] Figure 5 The current density-voltage-brightness diagram of the electroluminescent device doped with PhCzBCz of the product of Example 1-2;

[0052] Wherein, (a) is Example 1, and (b) is Example 2;

[0053] Figure 6 The current efficiency-brightness diagram of the electroluminescent device doped with PhCzBCz of the product of Example 1-2;

[0054] Wherein, (a) is Example 1, and (b) is Example 2;

[0055] Figure 7 The electroluminescence spectrum of the PhCzBCz electroluminescent device doped with the product of Example 1-2;

[0056] Wherein, (a) is Example 1, and (b) is Example 2;

[0057] Figure 8 This is a graph showing the external quantum efficiency of the electroluminescent device doped with PhCzBCz, the product of Example 1-2;

[0058] Among them, (a) is Example 1, and (b) is Example 2. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0061] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0062] Unless otherwise specified, the room temperature or normal temperature in the embodiments of the present invention refers to 25±3°C.

[0063] In the embodiment of the present invention 1 HNMR, 13 C NMR spectra were measured using a Bruker-400 NMR instrument.

[0064] Example 1

[0065] A method for preparing an organic electroluminescent material (t-BuDPAiPP) based on a pyrazine derivative comprises the following steps:

[0066] (1) Preparation of Intermediate 1: In a 100 ml double-necked flask, pyridine-3,4-diamine (0.445 g, 4.08 mmol), 1,2-bis(4-bromophenyl)ethane-1,2-dione (1.500 g, 4.08 mmol) and 50 ml of 95% ethanol solution were added in sequence, and the mixture was stirred at 90°C for 10 h. After the reaction was completed, the mixture was cooled to room temperature, and the ethanol in the system was removed. The mixture was then extracted with water and dichloromethane for 3 times (3×30 mL). The organic phases were combined and dried over anhydrous magnesium sulfate for 6 h, and filtered to obtain a crude product. The crude product was separated by silica gel column chromatography using 4:1 (V / V) petroleum ether and ethyl acetate as eluents to obtain 1.1854 g of Intermediate 1 (2,3-bis(4-bromophenyl)pyrido[3,4-b]pyrazine) as a white solid with a yield of 66.19%.

[0067] 1 HNMR (400MHz, CDCl 3 )δ9.58(s, 1 H),8.84(d,J=5.8Hz, 1 H),7.97(d,J=5.8Hz, 1 H),7.53(d,J=8.5Hz,4H),7.42(dd,J=8.6,3.0Hz,4H).HRMS calce for C 19 H 11 Br 2 N 3 [M] + 438.9320 found 438.8912.

[0068] (2) Preparation of t-BuDPAiPP: In a 100 ml double-necked bottle, 2,3-bis(4-bromophenyl)pyrido[3,4-b]pyrazine (0.339 g, 0.773 mmol), bis(4-(tert-butyl)phenyl)amine (0.500 g, 1.78 mmol), Pd 2 (dpa) 3 (0.0425 g, 0.046 mmol), Cs 2 CO 3 (1.001 g, 3.09 mmol), (t-Bu) 3 P.HBF 4 (0.014g, 0.046mmol) and 50ml 99.8% toluene solution. Stir the reaction at 110℃ in an oxygen-free atmosphere for 24h. After the reaction is completed, cool to room temperature, remove toluene from the system, extract with water and dichloromethane 3 times (3×30mL), combine the organic phases and dry with anhydrous magnesium sulfate for 6h, and filter. Then, use 9:1 (V / V) petroleum ether and ethyl acetate as eluents to separate the crude product by silica gel column chromatography to obtain 0.383g of orange solid 4,4'-(pyrido[3,4-b]pyrazine-2,3-diyl)bis(N,N-bis(4-(tert-butyl)phenyl)aniline) with a yield of 58.89%, recorded as t-BuDPAiPP.

[0069] 1 H NMR (400 MHz, CDCl 3 )δ9.56(m,1H),8.76(dd,J=20.5,5.7Hz,1H),7.92(d,J=15.0Hz,1H),7.53(q,J=8.8Hz,2H),7.45(d,J=1. 8Hz,2H),7.39(m,1H),7.31(dd,J=8.6,1.7Hz,7H),7.07(d,J=8.7Hz,8H),7.03(m,4H),1.33(s,36H).13C NMR(101MHz,CDCl 3 )δ149.74,149.40,147.14,146.85,146.24,144.37,143.86,143.64,131.70,131.27,130.87 ,130.54,130.23,126.33,126.24,125.12,125.01,120.49,120.18,34.42,31.46.HRMScalce for C 59 H 63 N 5 [M + H] +

[0070] 841.5083 found 842.5136.

[0071] Example 2

[0072] A method for preparing an organic electroluminescent material (t-BuDPAPQ) based on a pyrazine derivative, comprising the following steps:

[0073] (1) Preparation of Intermediate 2: In a 100 ml two-necked flask, pyridine-3,4-diamine (0.300 g, 2.75 mmol), 3,6-dibromophenanthrene-9,10-dione (1.001 g, 2.75 mmol), 10 ml of 95% ethanol solution and 50 ml of 95% acetic acid solution were added in sequence. The mixture was stirred at 90°C for 10 h. After the reaction was completed, the mixture was cooled to room temperature, the ethanol in the system was removed, and the mixture was extracted with water and dichloromethane three times (3×30 mL). The organic phases were combined and dried over anhydrous magnesium sulfate for 6 h, and filtered. The crude product was separated by silica gel column chromatography using 7:1 (V / V) petroleum ether and ethyl acetate as eluents to obtain 0.9870 g of Intermediate 2 (3,6-dibromodibenzo[f,h]pyrido[3,4-b]quinoxaline) as a white solid with a yield of 82.14%.

[0074] 1 H NMR (400 MHz, CDCl 3 )δ9.78(s,1H),9.25(d,J=8.6Hz,2H),8.90(d,J=3.4Hz,1H),8.61(d,J=5.2Hz,2H),8.14(d,J=6.2Hz,1H),7.90(d,J=8.6Hz,2H).HRMS calcefor C 19 H 9 Br 2 N 3 [M] + 436.9163 found 437.1928.

[0075] (2) Preparation of t-BuDPAPQ: In a 100 ml double-necked bottle, 3,6-dibromodibenzo[f,h]pyrido[3,4-b]quinoxaline (0.500 g, 1.14 mmol), bis(4-(tert-butyl)phenyl)amine (0.739 g, 2.63 mmol), Pd 2 (dpa) 3 (0.0629 g, 0.068 mmol), Cs 2 CO 3 (1.492 g, 4.58 mmol), (t-Bu) 3 P.HBF 4(0.020g, 0.069mmol) and 50ml 99.8% toluene solution. Stir the reaction at 110℃ in an oxygen-free atmosphere for 24h, stop the reaction, cool to room temperature, remove toluene from the system, extract with water and dichloromethane 3 times (3×30mL), combine the organic phases and dry with anhydrous magnesium sulfate for 6h, filter. Use 8:1 (V / V) petroleum ether and ethyl acetate as eluents to separate the crude product by silica gel column chromatography to obtain an orange-red solid N 3 ,N 3 ,N 6 ,N 6 -Tetrakis(4-(tert-butyl)phenyl)dibenzo[f,h]pyrido[3,4-b]quinoxaline-3,6-diamine 0.532 g, yield 55.59%, recorded as t-BuDPAPQ.

[0076] 1 H NMR (400 MHz, CDCl 3 )δ9.61(s,1H),9.09(dd,J=8.9,3.5Hz,2H),8.74(d,J=5.8Hz,1H),7.99(d,J=5.8Hz,1H),7.63(d,J=2.1Hz,2H ),7.37(ddd,J=13.8,8.9,2.1Hz,2H),7.28(dd,J=8.8,2.5Hz,8H),7.07(dd,J=8.6,3.8Hz,8H),1.34(s,36H). 13 C NMR (101 MHz, CDCl 3 )δ151.48,150.96,147.15,146.86,144.06,134.26,133.43,128.26,127.64,126.32,124 .89,124.65,123.38,122.83,122.49,121.87,121.35,114.76,114.18,34.44,31.47.HRMS calce for C 59 H 61 N 5

[0077] [M + H] + 839.4927 found 840.4980.

[0078] Technical Effects

[0079] Performance characterization and fabrication of single-layer polymer electroluminescent devices and testing of luminescent properties:

[0080] 1. Test Method

[0081] The UV-visible absorption spectrum of the product of Example 1-2 was measured by a U-3900 UV-visible spectrometer, and the fluorescence emission spectrum was measured by a Hitachi F-700 fluorescence spectrometer.

[0082] The single-light-emitting polymer electroluminescent device based on organic small molecule compound materials is composed of the following devices: an indium tin oxide (ITO) conductive glass substrate layer, PhCzBCz and TmPyPB as host materials and electron transport layers, respectively, and organic small molecules are doped into PPF hosts with different doping concentrations as light-emitting layers (EML). Among them, the substrate layer, host material and electron transport layer are stacked in sequence with the light-emitting layer, and the product of Example 1-2 accounts for 3-15wt.% in the light-emitting layer of the electroluminescent device.

[0083] The polymer electroluminescent device is obtained by sequentially stacking ITO / PEDOT:PSS, (30nm) / luminescent layer, (x wt%, 30nm) / TmPyPB, (40nm) / Liq(1nm) / Al. The preparation method comprises the following steps:

[0084] In 3×10 -6 OLEDs were fabricated on an ITO glass substrate layer (110 nm, 15 Ω / m2) under a substrate pressure of 100 μm. The active area of ​​each device was 0.09 cm 2 The deposition rate and thickness of all materials were monitored using an oscillating quartz crystal. The doped layers were deposited using two different sensors to monitor the deposition rate of the host material and the dopant material (electroluminescent material). The deposition rate of the host material was controlled at 0.2 nm·s -1 The deposition rate of the dopant material is adjusted according to the volume ratio of the dopant in the host material. The electroluminescence (EL) and current density-voltage (JV) characteristics of the device were measured by a constant current source (Keithley 2400 Source Meter) combined with a photometer (Photo Research SpectraScan PR655).

[0085] 2. Effect Characterization

[0086] Figure 1 The UV-visible absorption spectra of Examples 1-2 in different solutions are shown in Figure 1, where (a) is Example 1 and (b) is Example 2.

[0087] like Figure 1As shown, both molecules exhibit similar absorption in different solvents, indicating that their ground state electronic structures in various solvents are independent of the polarity of the solvent. In solution, their UV-visible absorption spectra exhibit two prominent bands. The broad absorption peaks near 435 and 480 nm are mainly due to the intramolecular charge transfer (ICT) between the diphenylamine donor and the pyrazine acceptor, and strong absorption peaks are formed at 335 nm and 299 nm due to π-π* transitions. Since both molecules maintain the same donor group, the position of the ICT absorption band is related to the intensity of the acceptor unit.

[0088] Figure 2 The fluorescence emission spectra of Examples 1-2 in different solutions are shown in Figure 1, where (a) is Example 1 and (b) is Example 2.

[0089] like Figure 2 As shown in Figure 2, the emission spectrum shifted from the low polarity solvent toluene to the high polarity solvent dichloromethane, confirming that the emitter underwent an ICT transition. This is due to the difference in dipole moment between the excited state and the ground state. The emission wavelengths of t-BuDPAiPP and t-BuDPAPQ in toluene solution were the shortest at 535nm and 570nm, and the longest at 606nm and 647nm in dichloromethane solution.

[0090] Figure 3 The fluorescence emission spectra of Example 1-2 in methanol / water mixtures with different water volume fractions.

[0091] Among them, (a) is Example 1, and (b) is Example 2.

[0092] like Figure 3 As shown in the figure, when the water volume fraction (f w ) increased from 0 to 30%, the fluorescence intensity of t-BuDPAiPP and t-BuDPAPQ hardly changed. w When the fluorescence intensity increases from 40% to 80%, it increases significantly. w The peak value was reached when t-BuDPAPQ f w When the fluorescence intensity increases from 40% to 70%, it increases significantly. w The strongest fluorescence intensity was reached at 0%, which was about 10.7 times that of 0%. This indicates that at a higher water volume fraction, these molecules begin to aggregate, and this aggregation state leads to enhanced fluorescence. This indicates that t-BuDPAiPP and t-BuDPAPQ have AIE properties.

[0093] Dissolve t-BuDPAiPP and t-BuDPAPQ in DCM, soak cotton swabs in t-BuDPAiPP and t-BuDPAPQ solutions, and then draw "B, C" patterns on filter paper to test their performance in the field of fluorescent anti-counterfeiting. The results are as follows: Figure 4 shown.

[0094] Figure 4 The simulation diagrams of the effects of Examples 1-2 in the field of fluorescent anti-counterfeiting, where (a) is Example 1 and (b) is Example 2. It can be seen that the drawn pattern is reduced after being smoked by hydrochloric acid vapor under sunlight, and the fluorescence of t-BuDPAiPP and t-BuDPAPQ are restored to the initial state after being gassed by ammonia vapor. This effect provides a basis for designing fluorescent anti-counterfeiting technologies with different performances.

[0095] Figure 5 The current density-voltage-brightness diagram of the PhCzBCz doped electroluminescent device of Example 1-2. Among them, (a) is Example 1, and (b) is Example 2.

[0096] like Figure 5 The turn-on voltage (Von) of t-BuDPAiPP and t-BuDPAPQ is 7.4 V. The higher turn-on voltage may be due to the imbalance of charge carrier mobility in these devices.

[0097] Figure 6 This is the current efficiency-brightness diagram of the PhCzBCz doped electroluminescent device of Example 1-2.

[0098] like Figure 6 As shown, the devices based on t-BuDPAiPP and t-BuDPAPQ showed 484.6 and 542.6 cd mw 2 The maximum brightness is 4.9 and 1.7cdA -1 The current efficiency (CE) of

[0099] Figure 7 The electroluminescence spectra of the PhCzBCz doped electroluminescent device of Example 1-2 are shown in Figure 1. (a) is Example 1, and (b) is Example 2.

[0100] like Figure 7 As shown, both devices exhibit the same EL spectra and emit strongly in the orange region with emission maxima at 546 and 594 nm.

[0101] Figure 8 The external quantum efficiency curves of the PhCzBCz doped electroluminescent devices of Examples 1-2 are shown in Figure 1. (a) is Example 1, and (b) is Example 2.

[0102] like Figure 8 As shown in Figure 2, when the doping concentration of the electroluminescent material is 9%, the EQE of the t-BuDPAiPP organic light-emitting device and the t-BuDPAPQ organic light-emitting device max 1.5% and 0.77% respectively.

[0103] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing an organic electroluminescent material based on a pyrazine derivative, characterized in that: The following steps are involved: The diamine compound and the diketone compound are mixed and reacted to obtain an intermediate, and the intermediate is then mixed with diphenylamine for a coupling reaction to obtain the organic electroluminescent material based on the pyrazine derivative.

2. The preparation method according to claim 1, characterized in that: The molar ratio of the diamine compound to the diketone compound is 1:

1.

3. The preparation method according to claim 2, characterized in that: The diamine compound is pyridine-3,4-diamine; and / or, The diketone compound is 1,2-bis(4-bromophenyl)ethane-1,2-dione or 3,6-dibromophenanthrene-9,10-dione.

4. The preparation method according to claim 1, characterized in that: The temperature of the mixed reaction is 90° C., the time is 10 hours, and the atmosphere is an oxygen-free atmosphere.

5. The preparation method according to claim 1, characterized in that: The molar ratio of the intermediate to diphenylamine is 1:2.

3.

6. The preparation method according to claim 1, characterized in that: The coupling reaction is a Buchwald-Hartwig coupling reaction, the coupling reaction temperature is 110° C., the time is 24 hours, and the atmosphere is an oxygen-free atmosphere.

7. An organic electroluminescent material based on a pyrazine derivative prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the organic electroluminescent material based on pyrazine derivatives as claimed in claim 7 in the field of fluorescent anti-counterfeiting.

9. Use of the organic electroluminescent material based on pyrazine derivatives as claimed in claim 7 in an electroluminescent device.

10. An electroluminescent device comprising a light-emitting layer, characterized in that: The light-emitting layer comprises the organic electroluminescent material according to claim 7.

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