A visible light excited long afterglow material and preparation method thereof

Abstract

The invention discloses a visible light excited long afterglow material and a preparation method thereof, comprising: mixing carbazole and anhydrous tetrahydrofuran; stirring at 0 degrees Celsius and adding sodium hydride, then heating to room temperature and stirring for 30 minutes; cooling the reaction temperature to 0 degrees Celsius, adding anhydrous tetrahydrofuran solution dissolved with m-hydroxybenzoyl chloride, stirring for reaction for 10 minutes, heating to room temperature and continuing to stir for reaction for 2 hours; treating and purifying to obtain a product, by introducing a hydroxyl group, the excitation spectrum range of the compound can be broadened, the hydroxyl group is connected to the meta position of the benzene ring connected to the carbonyl group in the structure, and the excitation spectrum is further extended to move to the visible light region; the excitation spectrum of the compound is extended to the visible light region, and can be excited by visible white light, thereby realizing a visible light excited organic long afterglow material.

Description

Technical Field

[0001] The invention relates to the technical field of long afterglow materials, in particular to a visible light excited long afterglow material and a preparation method thereof. Background Art

[0002] Metal-free organic long afterglow materials are a new type of material that can still emit light after the excitation light source is removed. Due to its advantages such as long life, persistent luminescence, large Stokes shift and rich excited state characteristics, it has a wide range of applications in bioimaging, photodynamic therapy, photocatalysis and other fields. However, it is difficult for pure organic molecules to produce room temperature phosphorescence due to the low intersystem crossing efficiency from the singlet state to the triplet excited state, the spin-forbidden radiative transition from the triplet state to the singlet ground state, the easy non-radiative relaxation from the low-lying triplet excited state, and the collision quenching of oxygen. In the past few years, people have greatly enhanced the intersystem crossing between singlet excited states and triplet excited states by introducing heavy halogen atoms and aromatic carbonyl groups, and have suppressed non-radiative transitions by constructing a rigid environment using some feasible strategies (such as crystal induction). A series of long afterglow materials with ultra-long lifetimes have been prepared by methods such as H-aggregation, host-guest doping, and polymerization. However, most of the existing organic long afterglow materials are achieved under ultraviolet light excitation, which will greatly limit the practical application of room temperature phosphorescent materials. Therefore, there is an urgent need for a visible light excited long afterglow material and its preparation method to solve the above problems. Summary of the invention

[0003] The present invention provides a visible light excited long afterglow material and a preparation method thereof, which can extend the excitation spectrum of the compound to the visible light region and can be excited by visible white light, thereby realizing a visible light excited organic long afterglow material.

[0004] To achieve the above object, the present invention provides the following technical solution: a visible light excited afterglow material, the material having the following structure:

[0005] .

[0006] Preferably, the hydroxyl group is attached to the meta position of the benzene ring to which the carbonyl group is attached in the structure.

[0007] Preferably, the excitation wavelength of the material is 405 nanometers.

[0008] A method for preparing a visible light excited long afterglow material comprises the following steps:

[0009] S1, mixing carbazole and anhydrous tetrahydrofuran;

[0010] S2, stirring at 0 degrees Celsius and adding sodium hydride, then warming to room temperature and stirring for 30 minutes;

[0011] S3, cooling the reaction mixture to 0 degrees Celsius, adding anhydrous tetrahydrofuran solution containing m-hydroxybenzoyl chloride, stirring the mixture for 10 minutes, and then heating the mixture to room temperature and stirring the mixture for 2 hours;

[0012] S4. Processing and purification are performed to obtain the product, and the product having the hydroxyl group connected to the meta position of the benzene ring connected to the carbonyl group in the structure is selected.

[0013] Preferably, in step S2, the molar ratio of carbazole to sodium hydride added is 1:1-1:3.

[0014] Preferably, in step S3, the molar ratio of carbazole to m-hydroxybenzoyl chloride is 1:1-1:3.

[0015] Preferably, in step S4, the processing and purification are specifically:

[0016] First, the reaction solvent tetrahydrofuran is removed by a rotary evaporator to obtain a crude product;

[0017] Second, separation and purification were performed by column chromatography, with the eluent being petroleum ether:ethyl acetate in a volume ratio of 5:1;

[0018] Third, the product obtained after removing the solvent by a rotary evaporator is recrystallized with ethanol to obtain a pure product as a white crystalline solid.

[0019] Compared with the prior art, the present invention has the following beneficial effects: in the present invention, the introduction of hydroxyl groups and the selection of connection sites play an important role in regulating the excitation spectrum of the compound; firstly, the introduction of hydroxyl groups can broaden the excitation spectrum range of the compound, and the hydroxyl group is connected to the meta position of the benzene ring connected to the carbonyl group in the structure, so as to further expand its excitation spectrum to the visible light region; so that the excitation spectrum of the compound is extended to the visible light region, and can be excited by visible white light, thereby realizing an organic long afterglow material excited by visible light; in addition, the organic long afterglow material synthesized by the present invention has a simple structure and is easy to synthesize, and the reaction can be completed almost at room temperature, which is simpler and easier to obtain than the synthesis of other organic long afterglow materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0021] In the attached picture:

[0022] Figure 1 The long afterglow material of the present invention 1 H NMR spectrum;

[0023] Figure 2The fluorescence and phosphorescence emission spectra of the solid-state long afterglow material of the present invention (a) and the lifetime diagram of each phosphorescence peak (b);

[0024] Figure 3 It is the excitation spectrum of the long afterglow material of the present invention and the emission spectrum of the visible white light LED;

[0025] Figure 4 It is a schematic diagram of the afterglow photograph of the visible light excited afterglow material of the present invention. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0027] Embodiment: A visible light-excited afterglow material, the material has the following structure:

[0028] ;

[0029] Among them, the hydroxyl group is connected to the meta position of the benzene ring connected to the carbonyl group in the structure; further expanding its excitation spectrum to move to the visible light region;

[0030] refer to Figure 1-4 As shown, the structure of the obtained compound is correct as proved by NMR test; photophysical test shows that it has strong phosphorescence emission, efficiency of 1.09%, and life of up to 0.4 seconds; and its optimal excitation wavelength is 405 nanometers, in the visible light region, and overlaps with the light emission of white LED lamps. When irradiated with white LED lamps, an obvious long afterglow phenomenon can be observed after removing the excitation light source, and the luminescence time lasts for nearly three seconds; when excited with the flashlight of a mobile phone, its long afterglow emission can also be found. This shows that the obtained product has the long afterglow property of visible light excitation.

[0031] A method for preparing a visible light excited long afterglow material comprises the following steps:

[0032] S1, mixing carbazole and anhydrous tetrahydrofuran;

[0033] S2, stirring at 0 degrees Celsius and adding sodium hydride, then warming to room temperature and stirring for 30 minutes; wherein the molar ratio of the added sodium hydride to carbazole is 1:1-1:3;

[0034] S3, cooling the reaction mixture to 0 degrees Celsius, adding anhydrous tetrahydrofuran solution dissolved with m-hydroxybenzoyl chloride, stirring the reaction for 10 minutes, and then warming the temperature to room temperature and continuing to stir the reaction for 2 hours; wherein the molar ratio of carbazole to m-hydroxybenzoyl chloride is 1:1-1:3;

[0035] S4. Processing and purification are performed to obtain the product, and the product having the hydroxyl group connected to the meta position of the benzene ring connected to the carbonyl group in the structure is selected.

[0036] Specifically: the reaction solvent tetrahydrofuran is removed by a rotary evaporator, and the obtained crude product is separated and purified by column chromatography, and the eluent is petroleum ether:ethyl acetate with a volume ratio of 5:1; the solvent is first removed by a rotary evaporator to obtain the product, and then recrystallized with ethanol to obtain a pure product as a white crystalline solid.

[0037] In a specific embodiment,

[0038] Add 1 gram of carbazole to the reaction flask, and then add 20 milliliters of anhydrous tetrahydrofuran; the amount of anhydrous tetrahydrofuran can be increased or decreased appropriately, for example, 15-30 milliliters, which corresponds to 1 gram of carbazole (5.98 mmol). If the amount of carbazole used in the reaction is increased or decreased, the volume of anhydrous tetrahydrofuran should also be increased or decreased;

[0039] Add 0.28 g of sodium hydride (0.28 g corresponds to 11.96 mmol, with a molar ratio of 1:2 relative to 1 g of carbazole) at 0°C with stirring, then warm to room temperature and stir for 30 minutes;

[0040] The reaction mixture was cooled to 0 degrees Celsius, and anhydrous tetrahydrofuran solution containing 1.87 g of m-hydroxybenzoyl chloride (5.98 mmol of carbazole and 11.96 mmol of m-hydroxybenzoyl chloride, with a ratio of 1:2 for carbazole and m-hydroxybenzoyl chloride) was added. The mixture was stirred for 10 minutes, and then the mixture was heated to room temperature and stirred for 2 hours. The amount of m-hydroxybenzoyl chloride used was as shown above and was proportional to carbazole. The amount of anhydrous tetrahydrofuran used did not need to be too accurate, as it only needed to dissolve m-hydroxybenzoyl chloride, so it could be expanded to 5-15 ml. However, if the amount of m-hydroxybenzoyl chloride was doubled, the amount of anhydrous tetrahydrofuran also needed to be increased.

[0041] For the above-mentioned heating and cooling operations, the 0 degree Celsius reaction can be carried out in a low-temperature reactor adjusted to 0 degrees Celsius, or an ice-water bath can also be used. When it is heated to room temperature, it is removed from the low-temperature reactor or the ice-water bath. When it is cooled to 0 degrees Celsius, the reaction is placed back in the low-temperature reactor or the ice-water bath for a period of time.

[0042] Finally, it should be noted that the above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A visible light excited afterglow material, characterized in that: The material has the following structure: 。 2. The visible light excited afterglow material according to claim 1, characterized in that: The excitation wavelength of the material is 405 nanometers.

3. A method for preparing a visible light-excited afterglow material, characterized in that: The steps include: S1, mixing carbazole and anhydrous tetrahydrofuran; S2, stirring at 0 degrees Celsius and adding sodium hydride, then warming to room temperature and stirring for 30 minutes; S3, cooling the reaction mixture to 0 degrees Celsius, adding anhydrous tetrahydrofuran solution containing m-hydroxybenzoyl chloride, stirring the mixture for 10 minutes, and then heating the mixture to room temperature and stirring the mixture for 2 hours; S4. Processing and purification are performed to obtain the product, and the product having the hydroxyl group connected to the meta position of the benzene ring connected to the carbonyl group in the structure is selected.

4. The method for preparing a visible light-excited afterglow material according to claim 3, characterized in that: In step S2, the molar ratio of carbazole to sodium hydride added is 1:1-1:

3.

5. The method for preparing a visible light-excited afterglow material according to claim 3, characterized in that: In step S3, the molar ratio of carbazole to m-hydroxybenzoyl chloride is 1:1-1:

3.

6. The method for preparing a visible light-excited afterglow material according to claim 3, characterized in that: In step S4, the processing and purification are specifically as follows: First, the reaction solvent tetrahydrofuran is removed by a rotary evaporator to obtain a crude product; Second, separation and purification were performed by column chromatography, with the eluent being petroleum ether:ethyl acetate in a volume ratio of 5:1; Third, the product obtained after removing the solvent by a rotary evaporator is recrystallized with ethanol to obtain a pure product as a white crystalline solid.

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