Organic phosphine oxide compound, green synthesis method thereof and application of organic phosphine oxide compound in blue light OLED (Organic Light Emitting Diode) device

Abstract

The invention discloses an organic phosphine oxide compound, a green synthesis method thereof and application of the organic phosphine oxide compound in a blue OLED device, and belongs to the technical field of preparation of dark blue OLED luminescent materials. The molecular formula of the organic phosphine oxide is C18H12Cl3PO, and the crystal structure of the organic phosphine oxide belongs to a P-1 space group of a triclinic system. The chromaticity coordinate x value of the organic phosphine oxide compound is close to the standard blue color, and the chromaticity coordinate y value of the organic phosphine oxide compound exceeds the standard blue color, so that the organic phosphine oxide compound belongs to a potential blue light emitting OLED material, and has good thermal stability when being used as a blue light emitting material in a blue light OLED device. According to the green synthesis method, the C18H12Cl3PO is obtained by oxidizing the C18H12Cl3P compound through hydrogen peroxide, the method does not depend on precious metal, the cost of the compound method is low, and the green synthesis requirement is met.

Description

Technical Field

[0001] The present application relates to an organic phosphine oxide compound and a green synthesis method thereof and application in a blue light OLED device, belonging to the technical field of preparation of deep blue OLED luminescent materials. Background Art

[0002] With the rapid development of processor technologies for electronic products such as mobile phones and computers, people have put forward higher requirements for display screens. In order to further enhance the visual experience of electronic products, display technology has become a hot topic of concern. Organic light-emitting diode (OLED) materials, as the foundation and core of OLED display technology, occupy an important position in this technology. As a new generation of display technology, OLED has attracted widespread attention in developed regions such as the United States and Europe.

[0003] OLED can be divided into two categories according to the type of organic light-emitting materials: one is small molecule OLED based on small molecule organic light-emitting materials, and the other is polymer OLED (PLED for short) based on conjugated polymer organic light-emitting materials. Keda of the United States and Cambridge of the United Kingdom are the industry leaders of small molecule OLED and polymer OLED respectively. So far, OLED materials have gone through the first generation of fluorescent materials represented by Alq3, phosphorescent materials represented by precious metals such as iridium (Ir), platinum (Pt), and rhenium (Re), and the third generation of materials based on thermally activated delayed fluorescence. Among the three primary colors of light (red, green, and blue), red and green phosphorescent materials have been mass-produced and applied on OLED displays. However, blue phosphorescent materials have weaknesses in color gamut breadth, so blue fluorescent materials are commonly used in commercial OLED displays. OLED display products sold on the market generally use red, green phosphorescent materials and blue fluorescent materials. Therefore, the color gamut breadth of blue light emitting materials is the focus of current research.

[0004] Efficient blue light emitting materials need not only good material properties, but also green and economical synthesis methods. In traditional metal coordination phosphorescent materials, precious metals and heavy metals not only increase the production cost of the materials, but also have a negative impact on the environment. Therefore, researchers are working hard to find alternative materials that do not rely on precious metals and explore environmentally friendly synthesis routes to promote the sustainable development of efficient blue light emitting materials. Summary of the invention

[0005] In order to solve the problem that it is difficult to have good thermal stability and a green and economical synthesis method while having good luminescent performance in the prior art of deep-range blue light OLED materials, the present application provides an organic phosphine oxide compound and a green synthesis method thereof and an application in a blue light OLED device, using hydrogen peroxide to oxidize C 18 H 12 Cl3P compound to obtain C18 H 12 The method of using Cl3PO compound has low cost and meets the requirements of green synthesis.

[0006] This application adopts the following technical solutions:

[0007] An organic phosphine oxide compound, the molecular formula of the organic phosphine oxide compound is:

[0008] C 18 H 12 Cl3PO.

[0009] Optionally, the crystal structure of the organophosphine oxide compound belongs to the triclinic system, P-1 space group.

[0010] Optionally, the unit cell parameters of the organic phosphine oxide compound are α=98.0770(10)°, β=109.3120(10)°, γ=115.2310(10)°, Z=4.

[0011] Optionally, the organophosphine oxide compound contains an asymmetric unit, wherein the asymmetric unit contains two central phosphorus atoms, two oxygen atoms are respectively linked to the center of the phosphorus atom, and six chlorophenyl groups with chlorine atoms at the para positions constitute two molecules.

[0012] According to another aspect of the present application, a method for preparing the above-mentioned organic phosphine oxide compound is provided, comprising the following steps:

[0013] Adding a hydrogen peroxide solution to a solution containing tri(4-chlorophenyl)phosphine and an alcohol to obtain a reaction raw material solution;

[0014] The reaction raw material liquid is placed in a sealed container and reacted to obtain the organic phosphine oxide compound.

[0015] Optionally, the alcohol is selected from at least one of methanol, ethanol, ethylene glycol and glycerol;

[0016] Optionally, the solution also includes water.

[0017] Optionally, the usage ratio of tri(4-chlorophenyl)phosphine to alcohol is 1 mmol:5-15 mL.

[0018] Optionally, the usage ratio of tri(4-chlorophenyl)phosphine to alcohol is selected from any value among 1mmol:5mL, 1mmol:7.5mL, 1mmol:10mL, 1mmol:12.5mL, 1mmol:15mL or any range value therebetween.

[0019] Optionally, the usage ratio of tri(4-chlorophenyl)phosphine to hydrogen peroxide is 1 mmol: 0.5-5 g.

[0020] Optionally, the usage ratio of tri(4-chlorophenyl)phosphine to hydrogen peroxide is selected from any value of 1mmol:0.5g, 1mmol:1g, 1mmol:2g, 1mmol:3g, 1mmol:4g, 1mmol:5g or any range between the two.

[0021] Optionally, the concentration of the hydrogen peroxide solution is 28-35 wt %.

[0022] Optionally, the reaction conditions include: reaction temperature of 20 to 55° C., and reaction time of 0.5 to 6 h.

[0023] Optionally, the reaction temperature in the reaction conditions is selected from any value among 20°C, 30°C, 40°C, 50°C, 55°C or any range therebetween.

[0024] Optionally, the reaction time in the reaction conditions is selected from any value among 0.5h, 1h, 2h, 3h, 4h, 5h, 6h or any range between two values.

[0025] Optionally, the reaction conditions include: reacting at a temperature of 40 to 55° C. for 5 to 15 minutes, then stopping heating and reacting under natural cooling conditions for 2 to 6 hours.

[0026] Optionally, the reaction is carried out under stirring conditions and the reaction is an oxidation reaction.

[0027] According to another aspect of the present application, there is also provided a use of the above-mentioned organic phosphine oxide compound or the organic phosphine oxide compound obtained according to the above-mentioned preparation method as a blue light emitting material in a blue light OLED device.

[0028] Optionally, the organic phosphine oxide compound has an optimal emission peak wavelength of 388 nm at an optimal excitation wavelength of 323 nm.

[0029] The beneficial effects of this application include:

[0030] The organic phosphine oxide compound provided in the present application has a deeper blue color gamut, and its color coordinates are (0.168, 0.058), compared with the standard blue color coordinates (0.14, 0.08). The color coordinate x value of the organic phosphine oxide compound in the present application is close to the standard blue, and the y value has exceeded the standard blue. It is a potential blue light-emitting OLED material, and has good thermal stability when used as a blue light emitting material in a blue light OLED device. The green synthesis method of the present application uses hydrogen peroxide to oxidize C 18 H 12 Cl3P compound to obtain C18 H 12 Cl3PO, does not rely on precious metals, and the method cost of the compound is low and meets the requirements of green synthesis. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 For this application sample C 18 H 12 Cl3P(a),C 18 H 12 Schematic diagram of the crystal asymmetric unit structure of Cl3PO(b).

[0032] Figure 2 For this application sample C 18 H 12 Cl3P(a),C 18 H 12 Schematic diagram of the crystal unit cell structure of Cl3PO(b).

[0033] Figure 3 For this application sample C 18 H 12 Cl3P(a),C 18 H 12 Liquid NMR spectrum of Cl3PO(b).

[0034] Figure 4 For this application sample C 18 H 12 Cl3P(a),C 18 H 12 X-ray powder diffraction pattern of Cl3PO(b).

[0035] Figure 5 For this application sample C 18 H 12 Cl3P,C 18 H 12 Fourier transform infrared spectrum of Cl3PO.

[0036] Figure 6 For this application sample C 18 H 12 Cl3P,C 18 H 12 Confocal Raman spectrum of Cl3PO.

[0037] Figure 7 For this application sample C 18 H 12 Cl3P,C 18 H 12 Thermal stability spectrum of Cl3PO.

[0038] Figure 8 For this application sample C18 H 12 Cl3P(a),C 18 H 12 Photoluminescence spectrum of Cl3PO(b).

[0039] Fig. 9 For this application sample C 18 H 12 Cl3P,C 18 H 12 CIE coordinates of Cl3PO. DETAILED DESCRIPTION

[0040] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0041] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0042] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0043] Example 1 Preparation of chemical formula C 18 H 12 Cl3PO organic phosphine oxide compounds

[0044] Using tri(4-chlorophenyl)phosphine as raw material, the compound tri(4-chlorophenyl)phosphine oxide was synthesized by solvent thermal reaction and hydrogen peroxide oxidation. The specific steps are as follows:

[0045] Weigh 3.0mmol of the organic phosphine compound tri(4-chlorophenyl)phosphine (CHP-Cl, 1096.9mg) and place it in a 200mL conical flask, add 30mL of anhydrous ethanol and 1 magnetic stirrer. Add an appropriate amount of tap water to the water bath to make the liquid level in the conical flask level with the liquid level in the water bath, then place it on a magnetic stirring table, and place the conical flask in a water tank. Slowly add 10mL of 30% hydrogen peroxide solution under magnetic stirring. After the hydrogen peroxide solution is completely added, stir magnetically for 10min in a 40℃ water bath, then remove the water bath, and continue to stir magnetically for 3h. After stirring, take a piece of filter paper and place it on a 100mL beaker to filter the liquid in the conical flask. The filtered filtrate is placed in a fume hood and allowed to stand for about 1 day until the solution is completely volatilized, and the oxidation product obtained is tri(4-chlorophenyl)phosphine oxide (CHPO-Cl), that is, an organic phosphine oxide compound.

[0046] Example 2 Preparation of Compound C 18 H 12 Cl3PO crystals

[0047] Weigh 0.5mmol tris(4-chlorophenyl)phosphine oxide (CHPO-Cl, 190.8mg) prepared in Example 1 into a 25mL beaker, add 10mL dichloromethane and use an ultrasonic device to fully dissolve the solid. After the solid is fully dissolved, add 5mL of n-hexane, shake the beaker slightly to mix the solution, then seal the beaker and ultrasonicate for 30 seconds. After the ultrasonication is completed, transfer the supernatant in the beaker to a 50mL beaker, seal it with plastic wrap and let it stand for about 3 days to evaporate, then precipitate high-quality crystals, and finally dry it naturally to obtain block crystals, marked as C 18 H 12 Cl3PO.

[0048] Comparative Example 1 Preparation of Compound C 18 H 12 Cl3P crystal

[0049] Weigh 0.5mmol tri(4-chlorophenyl)phosphine (CHP-Cl, 182.8mg) into a 50mL beaker, add 2mL methanol and use ultrasonic equipment to fully disperse the solid. After the solid is fully dispersed, add 5mL dichloromethane until the solution is clear and transparent, then seal the beaker and ultrasonicate for 30 seconds. After the ultrasonication is completed, transfer the solution in the beaker to a 100mL beaker, seal it with plastic wrap and let it stand for about 1 day to evaporate, then precipitate high-quality crystals, and finally dry it naturally to obtain block crystals, marked as C 18 H 12 Cl3P.

[0050] Test Example 1 Structural Characterization

[0051] The C prepared in Example 2 18 H 12 Cl3PO and C prepared in Comparative Example 1 18 H 12 Cl3P crystals were subjected to structural characterization:

[0052] X-ray single crystal diffraction test: Sample C 18 H 12 Cl3P、C 18 H 12 X-ray single crystal diffraction measurements of Cl3PO4 were performed on a Rigaku FR-X Microfocus single crystal instrument using a Cu target and a K α Radiation Source The test temperature is 293K. The structure is analyzed by Shelx. The test results are as follows Figure 1 , Figure 2 As shown, C 18 H 12 The asymmetric unit of Cl3P contains a central phosphorus atom and three chlorophenyl groups with chlorine atoms in the para positions; 18 H12 The asymmetric unit of Cl3PO contains two central phosphorus atoms, two oxygen atoms are linked to the center of the phosphorus atom, and six chlorophenyl groups with chlorine atoms at the para positions, forming two molecules.

[0053] NMR Test: Sample C 18 H 12 Cl3P、C 18 H 12 The NMR analysis of Cl3PO was performed on a Bruker AVANCE III 400 MHz NMR spectrometer. The solvent used was deuterated dimethyl sulfoxide. The 1 H NMR spectrum. Test structure as Figure 3 The chemical shift is related to the residual solvent peak (the position of the deuterated dimethyl sulfoxide solvent peak is 7.26 ppm). 18 H 12 Cl3P1 H NMR (400MHz, d-DMSO), δ (ppm): 7.47 (6H), 7.22 (6H); C 18 H 12 Cl3PO 1 H NMR (400MHz, d-DMSO), δ (ppm): 7.61 (6H).

[0054] X-ray powder diffraction phase test: Sample C 18 H 12 Cl3P、C 18 H 12 X-ray powder diffraction phase analysis (XRD) of ground Cl3PO was performed on a Rigaku SmartLab multifunctional X-ray diffractometer with a Cu target and a Kα radiation source. The test results are as follows Figure 4 Comparing the XRD diffraction theoretical pattern obtained by X-ray single crystal diffraction fitting with the XRD diffraction pattern measured by X-ray powder diffraction phase analysis, it can be seen that the XRD diffraction pattern obtained by single crystal data fitting is highly consistent with the XRD diffraction pattern measured experimentally, proving that the obtained sample is a sample of high purity and high crystallinity.

[0055] X-ray powder diffraction and X-ray single crystal diffraction results show that:

[0056] C before hydrogen peroxide oxidation 18 H 12 Cl3P is the Pbca space group of the orthorhombic system, and its unit cell parameters are α=90°, β=90°, γ=90°, Z=4; C after hydrogen peroxide oxidation18 H 12 Cl3PO is a triclinic crystal system with a P-1 space group and its unit cell parameters are α=98.0770(10)°, β=109.3120(10)°, γ=115.2310(10)°, Z=4.

[0057] C 18 H 12 Cl3P,C 18 H 12 The crystallographic data of Cl3PO are shown in Table 1.

[0058] Table 1 Sample C 18 H 12 Cl3P,C 18 H 12 Crystallographic data sheet of Cl3PO

[0059]

[0060]

[0061] Infrared spectrum test: Sample C 18 H 12 Cl3P、C 18 H 12 The infrared spectrum of the ground solid powder of Cl3PO was measured using a VERTEX 70 infrared spectrometer. Figure 5 As shown, 1191cm -1 、1176cm -1 、1120cm -1 The characteristic absorption peaks nearby can be attributed to the stretching vibration absorption of the P=O bond.

[0062] Confocal Raman spectroscopy test: Sample C 18 H 12 Cl3P、C 18 H 12 The confocal Raman spectra of the ground solid powder of Cl3PO4 were measured using a LabRAM HR confocal Raman spectrometer. Figure 6 As shown, 1180cm -1 The characteristic absorption peaks nearby can be attributed to the stretching vibration absorption of the P=O bond.

[0063] Test Example 2: Stability Test

[0064] The C prepared in Example 2 18 H 12 Cl3PO and C prepared in Comparative Example 1 18 H 12Thermal stability test of Cl3P crystal:

[0065] Sample C 18 H 12 Cl3P,C 18 H 12 The thermal stability of Cl3PO4 was measured by thermogravimetric analysis (TGA) on a METTLER TOLEDO analyzer in a nitrogen atmosphere. The sample was heated in an Al2O3 crucible at 10 K min -1 Heating at a heating rate of Figure 7 As shown, sample C after hydrogen peroxide oxidation 18 H 12 Cl3PO has good thermal stability and does not lose weight significantly before 300℃. Its thermal stability is significantly better than that of the pre-oxidized sample C. 18 H 12 Cl3P.

[0066] Test Example 3 Photoluminescence Performance Test

[0067] The C prepared in Example 2 18 H 12 Cl3PO and C prepared in Comparative Example 1 18 H 12 Photoluminescence performance test experiment of Cl3P crystal:

[0068] For sample C 18 H 12 Cl3P,C 18 H 12 Cl3PO was used to conduct a photoluminescence performance test experiment. The specific steps are as follows: the selected instrument is Edinburgh FLS1000 for photoluminescence performance test, where the excitation light source is a Xe lamp, and the ultraviolet light of a specific excitation band can be selected through the filtering system. The excitation slit is 1mm and the receiving slit is 1mm.

[0069] The experimental spectrum of photoluminescence is shown in Figure 8 For sample C 18 H 12 Cl3P, at the optimal excitation wavelength of 358nm, the sample exhibits single peak emission, and its optimal emission peak wavelength is 425nm. 18 H 12 Cl3PO, at the optimal excitation wavelength of 323nm, the sample also exhibits a single peak emission, and its optimal emission peak wavelength is 388nm. Organic phosphine / phosphine oxide compound C before and after hydrogen peroxide oxidation 18 H 12 Cl3P and C 18 H 12 Cl3PO emits blue light.

[0070] Sample C 18 H 12 Cl3P,C 18 H 12 The color coordinates of Cl3PO are as follows Fig. 9 As shown, all are in the blue light area, CIE coordinates: C 18 H 12 Cl3P(0.203,0.208),C 18 H 12 Cl3PO(0.168,0.058). The color temperatures are: C 18 H 12 Cl3P(1048499K), C 18 H 12 Cl3PO(2723K). (The higher the color temperature, the weaker the scattering ability and the weaker the penetration ability.)

[0071] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An organic phosphine oxide compound, characterized in that The molecular formula of the organic phosphine oxide compound is: C 18 H 12 Cl3PO。 2. The organic phosphine oxide compound according to claim 1, characterized in that The crystal structure of the organophosphine oxide compound belongs to the triclinic system and the P-1 space group.

3. The organic phosphine oxide compound according to claim 1, characterized in that The unit cell parameters of the organophosphine oxide compound are α=98.0770(10) o , β=109.3120(10) o ,γ=115.2310(10) o , Z=4.

4. The organic phosphine oxide compound according to claim 1, characterized in that The organophosphine oxide compound contains an asymmetric unit, wherein the asymmetric unit contains two central phosphorus atoms, two oxygen atoms are respectively linked to the center of the phosphorus atoms, and six chlorophenyl groups with chlorine atoms at the para positions constitute two molecules.

5. The method for preparing the organic phosphine oxide compound according to any one of claims 1 to 4, characterized in that: The steps include: Adding a hydrogen peroxide solution to a solution containing tri(4-chlorophenyl)phosphine and an alcohol to obtain a reaction raw material solution; The reaction raw material liquid is placed in a sealed container and reacted to obtain the organic phosphine oxide compound.

6. The preparation method according to claim 5, characterized in that: The alcohol is selected from at least one of methanol, ethanol, ethylene glycol and glycerol; Preferably, the solution also includes water.

7. The preparation method according to claim 5, characterized in that: The usage ratio of tri(4-chlorophenyl)phosphine to alcohol is 1 mmol:5-15 mL.

8. The preparation method according to claim 5, characterized in that: The usage ratio of tri(4-chlorophenyl)phosphine to hydrogen peroxide is 1mmol:0.5-5g.

9. The preparation method according to claim 5, characterized in that: The reaction conditions include: reaction temperature of 20-55° C., and reaction time of 0.5-6 h.

10. Use of the organic phosphine oxide compound according to any one of claims 1 to 4 or the organic phosphine oxide compound obtained according to the preparation method according to any one of claims 5 to 9 as a blue light emitting material in a blue light OLED device.

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