Preparation method of a small molecule imide derivative organic light-emitting material

Abstract

This invention discloses a method for preparing small-molecule imide derivative organic luminescent materials. Hexafluorodianhydride and 4-aminopyridine are added to a round-bottom flask, followed by the addition of an organic solvent. The mixture is stirred for a period of time to obtain a product intermediate. The intermediate is heated to 160°C and reacted for 4-6 hours, then cooled. A saturated sodium bicarbonate solution is added, and after standing, a precipitate forms. This precipitate is filtered, washed with saturated sodium chloride solvent, and dried to obtain the imide derivative luminescent material. The preparation steps of this invention are simple, low-cost, and the reaction conditions are mild, resulting in a high-purity product with excellent luminescent performance.

Description

Technical Field

[0001] This invention relates to the field of organic light-emitting materials technology, and in particular to a method for preparing small molecule imide derivative organic light-emitting materials. Background Technology

[0002] Organic light-emitting materials (OLEDs) exhibit great application potential in the display and lighting fields due to their superior properties such as high luminous efficiency, rich colors, fast response speed, and flexibility. Among them, imide derivatives, due to the presence of a rigid imide ring in their molecular structure, possess excellent thermal, chemical, and photochemical stability. Furthermore, their molecular structure is easily modified, allowing for the control of emission wavelength and luminous efficiency through the introduction of different substituent groups, making them one of the research hotspots in the field of OLEDs.

[0003] Currently, the preparation methods of small molecule imide derivative organic light-emitting materials have the following main drawbacks: First, the synthesis steps are cumbersome, usually requiring multiple coupling and acylation reactions, resulting in long reaction cycles and low preparation efficiency; second, some preparation methods require expensive catalysts (such as noble metal palladium catalysts) or special reaction reagents, leading to high preparation costs and hindering large-scale industrial production; third, the reaction conditions are harsh, requiring extreme conditions such as high temperature, high pressure, or anhydrous and oxygen-free environments, placing high demands on reaction equipment and posing certain safety hazards; fourth, some preparation methods yield products with low purity and unsatisfactory luminescence efficiency, limiting their practical applications. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing small molecule imide derivative organic light-emitting materials that is simple in procedure, low in cost, mild in reaction conditions, high in product purity and excellent in luminescence performance, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A small molecule imide derivative organic light-emitting material, the general structural formula of which is as follows:

[0007]

[0008] Ar1 is an aryl or heteroaryl group.

[0009] Furthermore, the general formula of the Ar1 structure is as follows:

[0010]

[0011] A method for preparing a small molecule imide derivative organic light-emitting material includes the following steps:

[0012] S1, add hexafluorodianhydride and 4-aminopyridine into a round-bottom flask, then add an organic solvent, and stir for a period of time to obtain the product intermediate;

[0013] S2, Set up a reflux apparatus, heat the intermediate product from step S1 to 160°C, react for 4-6 hours, and then cool.

[0014] S3, add saturated sodium bicarbonate solution, let stand, precipitate appears, filter, wash with saturated sodium chloride solvent, and dry to obtain imide derivative luminescent material.

[0015] Further, the organic solvent in step S1 is 1,2-dichlorobenzene.

[0016] Furthermore, the stirring time described in step S1 is 12-16 hours.

[0017] Furthermore, the molar ratio of hexafluorodianhydride and 4-aminopyridine added in step S1 should be 1:2.4.

[0018] Applications of an organic light-emitting material with thermally activated delayed fluorescence and high electron mobility: imide-based light-emitting materials are used in organic light-emitting diodes (OLEDs), photodetectors, and flexible display devices.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] High-purity target products can be obtained with only two core reactions, and the reaction time is shortened by more than 30% compared with traditional methods. This method uses inexpensive and readily available alkaline catalysts instead of precious metal catalysts, and the raw materials are all common chemical products, which significantly reduces costs. The reaction conditions are mild (140-160℃), requiring no extreme environment, with low equipment requirements and safe operation. The obtained product has a purity of over 98%, excellent luminescence performance, and the emission wavelength can be tuned in the range of 640 nm to 670 nm. The fluorescence quantum yield exceeds 4.77%, making it particularly suitable for industrial production in fields such as organic electroluminescent devices. Attached Figure Description

[0021] Figure 1 This is the 1H NMR spectrum of the imide derivative organic light-emitting material prepared in this invention;

[0022] Figure 2 This is the ultraviolet-visible absorption spectrum of the imide derivative organic light-emitting material prepared in this invention;

[0023] Figure 3 This is the fluorescence emission spectrum of the imide derivative organic light-emitting material prepared in this invention;

[0024] Figure 4This is the Fourier transform infrared spectrum of the imide derivative organic light-emitting material prepared in this invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] A small molecule imide derivative organic light-emitting material, the general structural formula of which is as follows:

[0027]

[0028] Ar1 is an aryl or heteroaryl group.

[0029] The general formula for the Ar1 structure is as follows:

[0030] .

[0031] The present invention will be further illustrated by specific embodiments below, but the present invention is not limited to these specific examples.

[0032] Example 1

[0033] An organic luminescent material containing a fluorinated small-molecule imide derivative (labeled L1) is prepared by the following steps: Under nitrogen protection, hexafluorodianhydride (2.22 g, 5.0 mmol) and 4-aminopyridine (1.13 g, 12.0 mmol) are added to a Shrek flask, followed by 50 mL of dehydrated 1,2-dichlorobenzene solution. The reaction is allowed to proceed for 12 h, then heated to 160 °C and refluxed with stirring for 4 h. The reaction is cooled to room temperature and spotted by thin-layer chromatography (TLC). After the reaction is complete, the cooled reaction solution is poured into 100 mL of water and extracted with ethyl acetate. The organic phase is dried over anhydrous sodium sulfate, the solvent is removed by rotary evaporation, and the mixture is washed three times with 50 mL of saturated NaHCO3 solution, followed by washing with saturated sodium chloride solution. After filtration, the mixture is dried overnight at 45 °C to obtain 2.59 g of a white solid compound, with a yield of 78%.

[0034] The reaction formula for this step is as follows:

[0035]

[0036] Example 2

[0037] An organic luminescent material containing a fluorinated small-molecule imide derivative (labeled L2) is prepared by the following steps: Under nitrogen protection, hexafluorodianhydride (2.22 g, 5.0 mmol) and 3-aminopyridine (1.13 g, 12.0 mmol) are added to a Shrek flask, followed by 50 mL of dehydrated 1,2-dichlorobenzene solution. The reaction is allowed to proceed for 12 h, then heated to 160 °C and refluxed with stirring for 4 h. The reaction is cooled to room temperature and spotted by thin-layer chromatography (TLC). After the reaction is complete, the cooled reaction solution is poured into 100 mL of water and extracted with ethyl acetate. The organic phase is dried over anhydrous sodium sulfate, the solvent is removed by rotary evaporation, and the mixture is washed three times with 50 mL of saturated NaHCO3 solution, followed by washing with saturated sodium chloride solution. After filtration, the mixture is dried overnight at 45 °C to obtain 2.39 g of a white solid compound, with a yield of 72%.

[0038] The reaction formula for this step is as follows:

[0039]

[0040] Performance testing of L1: emission wavelength of 660 nm, fluorescence quantum yield of 4.77%.

[0041] Example 3

[0042] UV-Vis absorption spectroscopy test

[0043] L1 was dissolved in pure DMSO to prepare a dilute solution with a concentration such that the absorbance A at the excitation wavelength was no greater than 0.05. The solution was scanned in the range of 200-800 nm using a UV-Vis spectrophotometer to obtain the UV-Vis absorption spectrum. The wavelength corresponding to the maximum absorption peak was recorded as 600 nm, which was used as the excitation wavelength for fluorescence testing.

[0044] Fluorescence emission spectroscopy test

[0045] The above ligand solution was placed in the sample cell of a fluorescence spectrometer. The excitation wavelength was set to the starting wavelength of the emission spectrum scan obtained in step 1, which was 600+15nm. The emission spectrum was scanned and the wavelength corresponding to the peak value was recorded. This wavelength is the maximum fluorescence emission wavelength of the ligand, which is 656nm.

[0046] Optionally, the emission wavelength is fixed at the measured 656 nm, and the excitation spectrum is scanned in reverse to verify the peak shape consistency between the obtained spectrum and the UV-Vis absorption spectrum in step 1.

[0047] Reference method for determining fluorescence quantum yield

[0048] A standard reference material with a known fluorescence quantum yield of 0.89 was selected. The emission wavelength of the standard reference material was close to that of the ligand to be tested (656 nm), and it was excited at the same excitation wavelength (600 nm) as the ligand to be tested.

[0049] The ligand solution to be tested and the standard reference solution were prepared separately. A series of concentrations were prepared using a gradient dilution method so that the absorbance A of each solution at the excitation wavelength of 600 nm was in the range of 0.01 to 0.05.

[0050] Under the same instrument parameters and 600 nm excitation, the fluorescence emission spectra of the ligand solution and the standard reference solution at various concentrations were measured.

[0051] The relative fluorescence quantum yield of the ligand to be tested is calculated using the following formula.

[0052]

[0053] In the formula, ψu represents the PLQY of the test object;

[0054] ψs — represents the standard object PLQY;

[0055] Iu—represents the integrated fluorescence intensity of the analyte;

[0056] Is—represents the integrated fluorescence intensity of the standard;

[0057] Au – represents the absorbance of the analyte;

[0058] As represents the absorbance of the standard.

[0059] Rhodamine B was used as the standard reference. The PLQY of Rhodamine B was measured to be 89%. The integrated fluorescence intensity was obtained by integrating its UV absorption curve using an excitation wavelength of 567 nm, and the corresponding absorbance was found in the fluorescence spectrum. The integrated fluorescence intensity was then obtained by volume integration using an excitation wavelength of 656 nm, and the corresponding absorbance was found in the fluorescence spectrum. The fluorescence quantum yield of the ligand in DMSO was calculated to be 4.77% using a formula.

[0060] The obtained ligands were characterized by ¹H NMR (400 MHz M, DMSO-d6) using a Bruker AVANCE I 400 NMR spectrometer. The results are as follows: Figure 1 As shown, the integrated areas of each peak are consistent with the number of hydrogen atoms and the chemical environment in the target ligand structure, and there are no obvious impurity peaks, indicating that the obtained ligand structure is correct and has high purity.

[0061] The obtained ligands were tested using a UV-3600 ultraviolet-visible spectrophotometer, and the results are as follows: Figure 2As shown in the spectrum, the ligand exhibits a characteristic absorption peak at 300 nm, which is attributed to the π→π bonds within the ligand. * The transition indicates that the ligand has a good conjugated system.

[0062] The fluorescence emission spectra of the obtained ligands were measured using an FLS 1000 series steady-state and transient fluorescence spectrometer with an excitation wavelength of 600 nm, as shown below. Figure 3 As shown, its maximum emission wavelength is at 656 nm, and the peak shape is symmetrical, indicating that the ligand has good fluorescence emission performance.

[0063] The obtained ligands were tested using a Nicolet AVATAR-360IR spectrometer with Fourier transform infrared spectroscopy (FTIR). The results are as follows: Figure 4 As shown. 30-30 cm⁻¹ in the spectrum. -1 The absorption peak at 1720 cm⁻¹ is attributed to the stretching vibration of the aromatic ring CH. -1 The absorption peaks are attributed to the stretching vibrations of the carbonyl group, and the characteristic functional group peaks are clear without any abnormal impurities, further confirming the ligand structure.

[0064] As can be seen from the above results, the compounds of the present invention all have good luminescence properties (maximum fluorescence emission wavelength of 660 nm and fluorescence quantum yield of 4.77%), and therefore have good application prospects in the fields of organic light-emitting diodes, photodetectors and flexible display devices.

[0065] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a small molecule imide derivative organic light emitting material, characterized by, Includes the following steps: S1, add hexafluorodianhydride and 4-aminopyridine into a round-bottom flask, then add an organic solvent, and stir for a period of time to obtain the product intermediate; S2, Set up a reflux apparatus, heat the intermediate product from step S1 to 160°C, react for 4-6 hours, and then cool. S3, add saturated sodium bicarbonate solution, let stand, precipitate appears, filter, wash with saturated sodium chloride solvent, and dry to obtain imide derivative luminescent material.

2. The method for preparing a small molecule imide derivative organic light-emitting material according to claim 1, characterized in that, The organic solvent in step S1 is 1,2-dichlorobenzene.

3. The method for preparing a small molecule imide derivative organic light-emitting material according to claim 1, characterized in that, The stirring time described in step S1 is 12-16 hours.

4. The method for preparing a small molecule imide derivative organic light-emitting material according to claim 1, characterized in that, The molar ratio of hexafluorodianhydride and 4-aminopyridine added in step S1 should be 1:2.

4.

5. The method for preparing a small molecule imide derivative organic light-emitting material according to claim 1, characterized in that, The general structural formula of the imide derivative luminescent material is as follows: Ar1 is an aryl or heteroaryl group.

6. The method for preparing a small molecule imide derivative organic light-emitting material according to claim 5, characterized in that, The general formula for the Ar1 structure is as follows: 。

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