An organic luminescent compound and its preparation method and application

Abstract

The present invention discloses an organic light-emitting compound and a preparation method and application thereof. The organic light-emitting compound has a structure as shown in the following formula (I). The organic light-emitting compound can emit strong pure blue light in cyclohexane and toluene solutions at room temperature, and the fluorescence quantum yield is ≥94.8%; in addition, the organic light-emitting compound can still emit strong fluorescence in the solid state and can be used to prepare organic blue light materials. Furthermore, the organic light-emitting compound has a magnetic response at 50°C and an ESR signal, and can be used as a new type of organic opto-electromagnetic functional material.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic light-emitting materials, and more specifically, relates to an organic light-emitting compound and a preparation method and application thereof. Background Art

[0002] New organic semiconductor materials have a series of excellent properties, such as (1) the manufacturing process of organic semiconductor devices is simple and low-cost; (2) large-area flexible devices can be prepared with light weight; (3) the size of organic semiconductor devices can be made smaller (molecular scale) and the integration is higher. The reduction of molecular scale and the increase of integration mean the reduction of operating power and the increase of operation speed. They can be prepared into field effect devices with significant energy-saving and efficiency-enhancing effects.

[0003] Among the three primary colors of red, green and blue (RGB), red and green light materials have basically met the requirements of industrialization, while blue light materials are still far behind red and green organic light emitting materials in terms of number of types, fluorescence efficiency, color purity, lifespan, brightness, service life, spectral purity, etc., which has become a technical problem for the industry. On the other hand, because green and red light can be converted from blue light, but not vice versa, blue light materials with excellent performance are indispensable key materials for the industry.

[0004] The blue light materials that have been developed so far are mainly high molecular polymers and small molecule compounds. Compared with polymers, small molecule blue light materials are easier to synthesize and purify, and are easier to prepare devices using the evaporation method. The resulting devices have better performance. Therefore, the development of small molecule blue light materials has attracted much attention.

[0005] Small molecule blue light materials mainly include aromatic hydrocarbons, aromatic amines, organic boron, organic silicon, etc. These small molecule blue light materials easily form intermolecular excimers or excimer complexes when emitting light, resulting in shortcomings such as low luminescence color purity, quantum efficiency and stability.

[0006] Therefore, the development of more new pure blue light organic materials with high fluorescence quantum yield is of great significance to the development of organic light-emitting materials. Summary of the invention

[0007] In view of the above existing technical problems, the primary purpose of the present invention is to provide an organic light-emitting compound, which has a fluorescence quantum yield of more than 94% in cyclohexane and toluene solutions at room temperature and can still emit pure blue fluorescence in the solid state.

[0008] The second object of the present invention is to provide a method for preparing an organic light-emitting compound.

[0009] The third object of the present invention is to provide an application of an organic light-emitting compound in the preparation of an organic blue light-emitting material or an organic light-emitting device.

[0010] A fourth object of the present invention is to provide an organic light emitting device.

[0011] The fifth object of the present invention is to provide an application of an organic light-emitting compound in the preparation of organic optoelectronic and electromagnetic functional materials.

[0012] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0013] The present invention claims protection for an organic light-emitting compound having a structure as shown in the following formula (I):

[0014]

[0015] The present invention provides an organic light-emitting compound, which can emit strong pure blue light in cyclohexane and toluene solutions at room temperature, and the fluorescence quantum yield is ≥94.8%; in addition, the organic light-emitting compound can still emit strong fluorescence in the solid state. Furthermore, the organic light-emitting compound has a magnetic response at 50°C and an ESR signal, and can be used as a new type of organic opto-electromagnetic functional material.

[0016] The organic luminescent compound provided by the present invention can provide a new idea for the design of organic blue light materials, has broad application prospects in organic blue light display materials, provides a new idea for the design of new pure blue light organic materials with high fluorescence quantum yield, and provides a new idea for the design of organic optoelectronic and electromagnetic functional materials.

[0017] Furthermore, the present invention claims a method for preparing an organic light-emitting compound, comprising the following steps:

[0018] S1. Under alkaline conditions, compound 1a, malononitrile and Lewis acid undergo a nucleophilic addition reaction, and an organic phase is extracted to obtain compound 1b;

[0019] S2. Compound 1b, compound 1c and a lithium reagent undergo a nucleophilic addition reaction at -70°C to -80°C to obtain compound 1d;

[0020] S3. Under a protective gas atmosphere, compound 1d and a reducing agent undergo a reduction reaction to obtain an organic light-emitting compound represented by formula (I);

[0021] The reaction formula of the preparation method is as follows:

[0022]

[0023] Further, in some specific embodiments, a method for preparing an organic light-emitting compound comprises the following steps:

[0024] S1. Under alkaline conditions, compound 1a, malononitrile, solvent and Lewis acid are mixed, heated under reflux to undergo a nucleophilic addition reaction, and water and an organic solvent are added to the reaction solution for extraction to obtain an organic phase to obtain compound 1b;

[0025] S2. Compound 1c, a solvent and a lithium reagent are mixed and reacted at -70°C to -80°C to obtain a reaction solution; Compound 1b is mixed with a solvent and then added to the reaction solution to react at -70°C to -80°C, and water and an organic solvent are added to extract to obtain an organic phase to obtain compound 1d;

[0026] S3. Under a protective gas atmosphere, compound 1d, a reducing agent and a solvent are mixed to undergo a reduction reaction to obtain an organic light-emitting compound represented by formula (I).

[0027] Preferably, in step S1, the alkaline condition is achieved by adding an alkali auxiliary agent, and the alkali auxiliary agent is selected from one or more of pyridine, triethylamine, diisopropylamine, isopropylamine and N-methylisopropylamine.

[0028] Preferably, in step S1, the Lewis acid is selected from one or more of titanium tetrachloride, aluminum trichloride, ferric chloride and boron trifluoride.

[0029] Preferably, in step S1, the reaction temperature of the nucleophilic addition reaction is 30-50°C.

[0030] Preferably, in step S1, the mass ratio of compound 1d, malononitrile and Lewis acid is 50:16-19:22-36.

[0031] Preferably, in step S2, the lithium reagent is selected from one or more of tert-butyl lithium, n-butyl lithium and lithium diisopropylamide.

[0032] Preferably, in step S2, the mass ratio of compound 1c to compound 1b is 26-30:15.

[0033] Preferably, in step S3, the protective gas may be nitrogen or an inert gas.

[0034] Furthermore, the present invention seeks to protect the use of an organic light-emitting compound in the preparation of an organic blue light material or an organic light-emitting device.

[0035] Furthermore, the present invention seeks to protect an organic light-emitting device, comprising the above-mentioned organic light-emitting compound.

[0036] Furthermore, the present invention seeks to protect the use of the above-mentioned organic light-emitting compound in the preparation of organic optoelectronic and electromagnetic functional materials.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention provides an organic light-emitting compound, which can emit strong pure blue light in cyclohexane and toluene solutions at room temperature, and the fluorescence quantum yield is as high as 94.8%; in addition, the organic light-emitting compound can still emit strong fluorescence in the solid state. Furthermore, the organic light-emitting compound has a magnetic response at 50°C and an ESR signal, and can be used as a new type of organic opto-electromagnetic functional material. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the NMR image of compound 1b.

[0040] Figure 2 This is the NMR image of compound 1d.

[0041] Figure 3 This is the NMR image of compound MAM.

[0042] Figure 4 This is the single crystal structure diagram of compound MAM.

[0043] Figure 5 The UV and PL images of the compound MAM in toluene solution and the PL image of the compound MAM solid powder are shown in FIG. Figure 5 A in the figure is the UV and PL images of compound MAM in toluene solution; Figure 5 Figure B is the PL image of the solid powder of compound MAM.

[0044] Figure 6 The UV and PL images, fluorescence photos and optical data of compound MAM in different solvents are shown. Figure 6 A in the figure is the UV image of compound MAM in different solvents; Figure 6 B in the figure is the PL graph of compound MAM in different solvents; Figure 6 C in the figure is the fluorescence photos of the compound MAM in different solvents; Figure 6 D in the figure is the optical data of compound MAM in different solvents.

[0045] Figure 7 These are the ESR spectra of compound MAM in toluene solution and in solid state at 50°C.

[0046] in, Figure 7 A in FIG. 1 is the ESR spectrum of compound MAM in toluene solution; Figure 7 B in FIG. 1 is the ESR spectrum of compound MAM in the solid state. DETAILED DESCRIPTION

[0047] The present invention is further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0048] Compound 1c in the example can be synthesized with reference to Asian Journal of Organic Chemistry (2018), 7(9), 1864-1871, and other materials are chemical raw materials commonly used in pharmaceutical chemicals and can be easily obtained from the market.

[0049] Example 1 Preparation of organic light-emitting compounds

[0050]

[0051] (1) Synthesis of compound 1b

[0052] At room temperature, 50 g of compound 1a, 19.04 g of malononitrile, 250 mL of dichloromethane and 9.5 g of pyridine were added to a 500 mL reaction bottle in sequence, stirred at 0 ° C for 0.5 h, and 22.77 g of titanium tetrachloride was slowly added dropwise. After the addition was completed, the reaction solution was heated (40-45 ° C) to reflux and stirred for 10 h. TLC detected the raw materials until the reaction was completed, and the reaction solution cooled to room temperature. Prepare 50 mL of ice water, pour the above reaction solution into the ice water, stir for 10 minutes and then separate the liquids. Separate the aqueous phase, add 200 ml of dichloromethane to extract the aqueous phase, combine the two separated organic phases, and concentrate to dryness to obtain a yellow product, which is compound 1b, with an isolation yield of 92% (the NMR image of compound 1b is as shown in Figure 1 shown).

[0053] (2) Synthesis of compound 1d

[0054] At room temperature, add 30g of compound 1c and 150ml of anhydrous tetrahydrofuran to a 250mL eggplant-shaped bottle, cool to -78°C, keep warm and stir for 0.5h, and slowly add 2.5M tert-butyl lithium (t-BuLi) dropwise. During the addition, control the temperature of the reaction system not to exceed -70°C. After the addition, keep warm and stir for 1h. In another reaction bottle, add 15g of compound 1b, add 30ml of anhydrous tetrahydrofuran (THF), and stir at room temperature to dissolve. Add the tetrahydrofuran solution of compound 1b to the reaction solution of compound 1c slowly. During the addition, control the temperature of the reaction system not to exceed -70°C. After the addition, stir the reaction system at -70°C for 3h. The raw material was detected by TLC until the reaction was completed, and 2 ml of water was slowly added dropwise to terminate the reaction. The reaction solution was then warmed to room temperature and concentrated to dryness at 50°C. 60 ml of dichloromethane and 30 ml of water were added for extraction and separation. The organic phase was warmed to 40°C and concentrated to dryness to obtain a light yellow product, namely compound 1d, with a yield of 95.3% (the NMR image of compound 1d is shown in FIG. Figure 2 shown).

[0055] (3) Synthetic compound MAM

[0056] Add 60g of compound 1d to a 500ml reaction bottle at room temperature, add 300ml of anhydrous dichloromethane (DCM), and stir at room temperature for 30min. Add 24.7g of anhydrous tin dichloride in batches, and after the addition, stir at room temperature for 3h under nitrogen protection. Detect the raw material by TLC until the reaction is completed, filter with suction, and concentrate the filtrate to dryness to obtain the product formula (I) compound (abbreviated as MAM), with a yield of 98.4% (the NMR image of compound MAM is as follows Figure 3 As shown, the single crystal structure of compound MAM is shown in Figure 4 shown).

[0057] Example 2 Preparation of organic light-emitting compounds

[0058] The difference between this example and Example 1 is that in step (1), 16.01 g of aluminum trichloride is used to replace 22.77 g of titanium tetrachloride. The final isolation yield of compound 1b is 91%.

[0059] Example 3 Preparation of organic light-emitting compounds

[0060] The difference between this example and Example 1 is that in step (1), 12.15 g of triethylamine is used to replace 9.5 g of pyridine. The final isolated yield of compound 1b is 89%.

[0061] Example 4 Preparation of organic light-emitting compounds

[0062] The difference between this example and example 1 is that in step (2), n-butyl lithium is used instead of tert-butyl lithium. The final isolated yield of compound 1d is 94.2%.

[0063] Example 5

[0064] Weigh 5.36 mg of compound MAM and dissolve it in 10 mL of anhydrous toluene to prepare a concentration of 1x10 -3 mol / L. The maximum absorption wavelength of compound MAM in toluene solution was used as the excitation wavelength, and the maximum emission wavelength of compound MAM in toluene solution was tested to determine the fluorescence spectrum of compound MAM. The fluorescence photograph of compound MAM solid powder was taken under 365nm fluorescent light. The fluorescence quantum yield of compound MAM solid powder was the fluorescence quantum yield measured by steady-state-transient fluorescence spectroscopy with the maximum absorption wavelength as the excitation wavelength.

[0065] Figure 5The UV (ultraviolet absorption spectrum) and PL (fluorescence emission spectrum) diagrams of the compound MAM in toluene solution and the PL diagram of the compound MAM solid powder are shown in the figure. It can be seen from the figure that the maximum emission wavelength of the compound is 479nm, and it can still emit strong fluorescence in the solid state, with an emission wavelength of 461nm.

[0066] Example 6

[0067] Weigh 5.36 mg of compound MAM and dissolve it in 10 mL of anhydrous cyclohexane, anhydrous dichloromethane (DCM), anhydrous toluene, anhydrous dioxane and tetrahydrofuran (THF) respectively, with a concentration of 1x10 -3 mol / L, UV-visible absorption spectra of the test compound MAM in different solvents. Fluorescence emission spectra The maximum absorption wavelength of the compound MAM in different solvents was used as the excitation wavelength to test the fluorescence emission wavelength of the test compound MAM in different solvents.

[0068] Figure 6 The UV and PL images, fluorescence photos and optical data of compound MAM in different solvents. It can be seen from the figure that the compound has obvious solvent efficiency and a large Stokes shift. In cyclohexane and toluene, it emits strong pure blue light, with maximum emission wavelengths of 449nm and 479nm, respectively, and fluorescence quantum yields of up to 94.8% and 96.6%, respectively.

[0069] Example 7

[0070] Weigh 20 mg of compound MAM, place it in a dry ESR tube, add 5 mL of anhydrous toluene, heat it to 50°C, and detect the ESR signal. Weigh 50 mg of compound MAM, place it in a dry ESR tube, heat it to 50°C, and detect the ESR signal.

[0071] Figure 7 The ESR spectra of compound MAM in toluene solution and in solid state at 50°C are shown in the figure. As can be seen from the figure, the g value of compound MAM in toluene solution is 2.0025, and the g value of compound MAM in solid state is 2.0027, which is a typical singlet free radical. This indicates that the compound tends to transform from a closed shell structure to an open shell structure after heating. In addition, it can be seen from the figure that the compound also has a magnetic response at 50°C, with ESR signals and magnetic properties, and has great application prospects in the field of organic optoelectronic and electromagnetic functional materials.

[0072] The present invention provides an organic light-emitting compound, which can emit strong pure blue light in cyclohexane and toluene solutions at room temperature, and the fluorescence quantum yield is ≥94.8%; in addition, the organic light-emitting compound can still emit strong fluorescence in the solid state. Furthermore, the organic light-emitting compound has a magnetic response at 50°C and an ESR signal, and can be used as a new type of organic opto-electromagnetic functional material. The organic light-emitting compound provided by the present invention can provide a new idea for the design of organic blue light materials, has broad application prospects in organic blue light display materials, and provides a new idea for the design of new pure blue light organic materials with high fluorescence quantum yields and the design of organic opto-electromagnetic functional materials.

[0073] The foregoing examples are merely illustrative and are used to explain some features of the method of the present invention. The appended claims are intended to require the widest possible range that can be imagined, and the embodiments presented herein are demonstrated by the applicant's actual test results. Therefore, the applicant's intention is that the appended claims are not limited by the selection of examples that illustrate the features of the present invention. Some numerical ranges used in the claims also include sub-ranges therein, and changes in these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. An organic light-emitting compound, characterized in that: The compound has a structure shown in the following formula (I):

2. The method for preparing the organic light-emitting compound according to claim 1, characterized in that: The following steps are involved: S1. Under alkaline conditions, compound 1a, malononitrile and Lewis acid undergo a nucleophilic addition reaction, and an organic phase is extracted to obtain compound 1b; S2. Compound 1b, compound 1c and a lithium reagent undergo a nucleophilic addition reaction at -70°C to -80°C to obtain compound 1d; S3. Under a protective gas atmosphere, compound 1d and a reducing agent undergo a reduction reaction to obtain an organic light-emitting compound represented by formula (I); The reaction formula of the preparation method is as follows:

3. The preparation method according to claim 2, characterized in that: In the step S1, the alkaline condition is achieved by adding an alkali auxiliary agent, and the alkali auxiliary agent is selected from one or more of pyridine, triethylamine, diisopropylamine, isopropylamine and N-methylisopropylamine.

4. The preparation method according to claim 2, characterized in that: In the step S1, the Lewis acid is selected from one or more of titanium tetrachloride, aluminum trichloride, ferric chloride and boron trifluoride.

5. The preparation method according to claim 2, characterized in that: In the step S1, the reaction temperature of the nucleophilic addition reaction is 30-50°C.

6. The preparation method according to claim 2, characterized in that: In step S2, the lithium reagent is selected from one or more of tert-butyl lithium, n-butyl lithium and lithium diisopropylamide.

7. The preparation method according to claim 2, characterized in that: In step S3, the reducing agent is selected from one or more of stannous chloride, ferrous chloride, cupric chloride and titanium trichloride.

8. Use of the organic light-emitting compound according to claim 1 in the preparation of organic blue light materials or organic light-emitting devices.

9. An organic light-emitting device, characterized in that: Comprising the organic light-emitting compound as claimed in claim 1.

10. Use of the organic light-emitting compound according to claim 1 in the preparation of organic opto-electromagnetic functional materials.

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