Thermal activation delayed fluorescence material, and preparation method and application thereof

Abstract

The invention discloses a thermal activation delayed fluorescent material as well as a preparation method and application thereof, the general formula of the thermal activation delayed fluorescent material is as shown in formula I: # imgabs0 #, X is O or S, and R is a benzimidazole group or an indole group or a 1, 2, 3, 4-tetrahydroisoquinoline group or a 1H-naphtho [2, 3-D] imidazole group. The invention innovatively combines the characteristics of thermal activation delayed fluorescence and aggregation-induced emission, and develops a preparation strategy of the aggregation-induced emission thermal activation delayed fluorescence material. Through the strategy, a series of aggregation-induced thermal activation delayed fluorescence materials are successfully synthesized, and the compounds not only show excellent thermal activation delayed fluorescence ability, but also have a remarkable aggregation-induced emission enhancement effect; therefore, the organic light-emitting material has wide potential application value in the fields of biological imaging technology, organic light-emitting material application and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic light-emitting materials, and particularly relates to a thermally activated delayed fluorescence material, a preparation method thereof, and an application thereof. Background Art

[0002] In the forefront of exploring advanced luminescent materials, the technology of thermally activated delayed fluorescence materials (TADF) has attracted much attention due to its unique luminescence mechanism and excellent photophysical properties. TADF materials can not only exhibit delayed fluorescence effects after being thermally excited, effectively extending the luminescence lifetime and improving the luminescence efficiency, but also show aggregation-induced emission (AIE) properties when these materials are in an aggregated state, that is, the luminescence intensity is significantly enhanced in the molecular aggregation rather than the dispersed state. The combination of these dual properties opens up new possibilities for the application of TADF materials in multiple fields, especially in the field of biomaterials.

[0003] In biomaterials science, the synergistic effect of TADF and AIE properties enables these materials to be applied in fields such as bio-labeling, bio-imaging, and biosensing. They can not only achieve highly sensitive detection of biomolecules through efficient fluorescence emission, but also maintain stable luminescence performance in complex biological environments, overcoming the limitation of traditional fluorescent dyes being easily quenched in the aggregated state. In addition, the long-lifetime luminescence characteristics of TADF materials enable time-resolved fluorescence imaging, further enhancing the accuracy and depth of bioanalysis.

[0004] Based on this, the present invention aims to provide a thermally activated delayed fluorescence material with both thermally activated delayed fluorescence characteristics and enhanced aggregation-induced emission effect.

[0005] The information disclosed in this background art section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as an admission or any form of suggestion that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Invention

[0006] The purpose of the present invention is to provide a thermally activated delayed fluorescence material, a preparation method thereof, and an application thereof. The thermally activated delayed fluorescence material has excellent thermally activated delayed fluorescence ability and significant enhanced aggregation-induced emission effect.

[0007] In order to achieve the above purpose, the technical solution provided by a specific embodiment of the present invention is as follows:

[0008] A thermally activated delayed fluorescence material, whose general formula is shown in Formula I:

[0009]

[0010] Among them, X is O or S, and R is a benzimidazole group, an indole group, a 1,2,3,4-tetrahydroisoquinoline group, or a 1H-naphtho[2,3-d]imidazole group.

[0011] The technical solution provided by another specific embodiment of the present invention is as follows:

[0012] A preparation method of a thermally activated delayed fluorescence material, comprising:

[0013] Adding a halogenated benzophenone, a phenazine substance, and a donor substance corresponding to the R group to an organic solvent, adding a base, reacting at 80°C to 100°C for 12 h to 24 h, and cooling to room temperature after the reaction;

[0014] Adding a sufficient amount of distilled water to the reaction solution to obtain a solid substance, then using an extractant to extract and separate the solid substance, and collecting the organic phase;

[0015] Drying, separating, and purifying the organic phase to obtain a thermally activated delayed fluorescence material.

[0016] In one or more embodiments of the present invention, the molar ratio of the halogenated benzophenone, the phenazine substance, the donor substance corresponding to the R group, and the base is (1 to 2):(1 to 2):(1 to 2):(2 to 5).

[0017] In one or more embodiments of the present invention, the organic solvent is DMF or DMSO, and based on 1 mol of the halogenated benzophenone, the amount of the organic solvent used is 5 to 10 mL.

[0018] In one or more embodiments of the present invention, the halogenated benzophenone is 4,4'-difluorobenzophenone or 4,4'-dibromobenzophenone.

[0019] In one or more embodiments of the present invention, the phenazine substance is phenothiazine or phenoxazine.

[0020] In one or more embodiments of the present invention, the donor substance corresponding to the R group is benzimidazole, indole, 1,2,3,4-tetrahydroisoquinoline, or 1H-naphtho[2,3-d]imidazole.

[0021] In one or more embodiments of the present invention, the base is Na2CO3, K2CO3, or NaH.

[0022] In one or more embodiments of the present invention, the separation and purification operation is to pass the dried organic phase through a chromatography column, and the eluent used during chromatography is a petroleum ether and ethyl acetate with a volume ratio of 1:(3 to 5).

[0023] The technical solution provided by another specific embodiment of the present invention is as follows:

[0024] The application of the above-mentioned thermally activated delayed fluorescence material or the thermally activated delayed fluorescence material prepared by the preparation method of the above-mentioned thermally activated delayed fluorescence material in the fields of biological labeling, bioimaging and biosensing.

[0025] Compared with the prior art, the thermally activated delayed fluorescence material in the present invention has an aggregation-induced emission effect, emits weakly in a pure organic solution, and shows the phenomenon of aggregation-induced emission in organic-aqueous mixed solutions such as DMF / H2O and THF / H2O. Its aggregated state is in an aqueous solution environment, with good biocompatibility and low toxicity. Brief Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for description in the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 1H NMR spectrum of the thermally activated delayed fluorescence material in Example 1 of the present invention;

[0028] Figure 2 1H NMR spectrum of the thermally activated delayed fluorescence material in Example 2 of the present invention;

[0029] Figure 3 1H NMR spectrum of the thermally activated delayed fluorescence material in Comparative Example 1 of the present invention;

[0030] Figure 4 1H NMR spectrum of the thermally activated delayed fluorescence material in Comparative Example 2 of the present invention;

[0031] Figure 5 Fluorescence spectra of the thermally activated delayed fluorescence material in Example 1 of the present invention in mixed solvents of THF and water with different ratios;

[0032] Figure 6 Fluorescence photos of the thermally activated delayed fluorescence material in Example 1 of the present invention in mixed solvents of THF and water with different ratios;

[0033] Figure 7 Lifetime change curve of the thermally activated delayed fluorescence material in Example 1 of the present invention under variable temperature conditions;

[0034] Figure 8 Lifetime change curve of the thermally activated delayed fluorescence material in Comparative Example 1 of the present invention under variable temperature conditions. Detailed Description of the Invention

[0035] To enable those skilled in the art to better understand the technical solutions in the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] A specific embodiment of the present invention provides a thermally activated delayed fluorescence material with the general formula as Formula I: Wherein, X is O or S, and R is a benzimidazole group, an indole group, a 1,2,3,4-tetrahydroisoquinoline group, or a 1H-naphtho[2,3-d]imidazole group.

[0037] Specifically, the present invention is based on the conformational design of a donor-acceptor-donor (D-A-D) structure, and by selecting specific X and R groups, the material is endowed with unique thermally activated delayed fluorescence (TADF) characteristics, and it also has a significant aggregation-induced emission enhancement (AIE) effect, showing broad potential application value in the fields of bioimaging technology and the application of organic light-emitting materials, etc.

[0038] Another specific embodiment of the present invention provides a preparation method of a thermally activated delayed fluorescence material, including Steps 1-2.

[0039] Step 1: Add a halogenated benzophenone, a phenazine substance, and a donor substance corresponding to the R group to an organic solvent, add a base, and react at 80°C to 100°C for 12h to 24h, and then cool to room temperature after the reaction.

[0040] Specifically, the halogenated benzophenone is 4,4'-difluorobenzophenone or 4,4'-dibromobenzophenone, the phenazine substance is phenothiazine or phenoxazine, and the R group donor substance is benzimidazole, indole, 1,2,3,4-tetrahydroisoquinoline, or 1H-naphtho[2,3-d]imidazole.

[0041] Benzimidazole - based molecules have good thermal stability and can remain stable at high temperatures without easy decomposition or deterioration. Since some organic optoelectronic devices need to operate at relatively high temperatures, thermally activated delayed fluorescence materials containing benzimidazole structures have better practical applications. Benzimidazole has unique photophysical properties, such as high fluorescence quantum yield and long fluorescence lifetime. When benzimidazole is used as the donor of thermally activated delayed fluorescence materials, it can effectively absorb and emit photons, thereby improving the luminescence efficiency of the device. In addition, by introducing different substituents on the benzimidazole molecule, its optical properties, such as absorption wavelength, emission wavelength, and fluorescence quantum yield, can be regulated. This tunability enables benzimidazole to meet different application requirements and optimize the device performance when used as the donor of thermally activated delayed fluorescence materials.

[0042] Furthermore, the base is Na2CO3 or K2CO3 or NaH, and the organic solvent is DMF (dimethylformamide) or DMSO (dimethyl sulfoxide). The above - mentioned raw materials react under alkaline conditions to form the target product. By controlling the reaction temperature and time, the formation of the target product can be promoted. In terms of the amount of raw materials used, the molar ratio of halogenated benzophenone, phenazine - based substance, the donor substance corresponding to the R group, and the base is (1 - 2):(1 - 2):(1 - 2):(2 - 5). Based on 1 mol of halogenated benzophenone, the amount of the organic solvent used is 5 - 10 mL.

[0043] Step 2: Add sufficient water to the reaction solution to obtain a solid substance, then use an extractant to extract and separate the solid substance, collect the organic phase, dry and purify the organic phase to obtain the thermally activated delayed fluorescence material.

[0044] Specifically, the extractant is dichloromethane. By using a large amount of distilled water, a yellow solid crude product is precipitated. To further improve the purity, the filtered yellow solid crude product is extracted multiple times with the extractant to obtain the organic phase, then the organic phase is dried with anhydrous sodium sulfate, and then separated and purified by a chromatography column. During chromatography, the eluent is a petroleum ether and ethyl acetate with a volume ratio of 1:(3 - 5).

[0045] Another specific embodiment of the present invention provides an application of the above - mentioned thermally activated delayed fluorescence material, specifically applied to the fields of biological labeling, bioimaging, and biosensing.

[0046] The following further elaborates on the present invention with specific examples.

[0047] Example 1

[0048] In this example, the synthesis route of the thermally activated delayed fluorescence material is as follows:

[0049]

[0050] Specifically, 1 mol of 4,4'-difluorobenzophenone, 1 mol of phenothiazine, and 1 mol of 1H-naphtho[2,3-d]imidazole were added to 10 ml of dimethylformamide solvent, and 3 mol of potassium carbonate was added simultaneously. The reaction mixture was heated to 80 °C and stirred for 12 hours. After the reaction was completed, heating was stopped and the mixture was cooled to room temperature.

[0051] Subsequently, a large amount of distilled water was added to the cooled reaction solution to form a yellow solid, which was then filtered. Dichloromethane was added multiple times to extract the yellow solid, and liquid separation was carried out separately. This extraction-liquid separation step was repeated three times. The organic phases were combined and dried over anhydrous sodium sulfate. Then, purification was carried out by column chromatography. During chromatography, the eluent was a mixture of petroleum ether and ethyl acetate with a volume ratio of 1:5. After chromatography, the target compound, i.e., the thermally activated delayed fluorescence material, was obtained.

[0052] The 1H NMR spectrum of the thermally activated delayed fluorescence material is as Figure 1 shown, and the NMR data are as follows: 1 H NMR(500MHz,DMSO-d6)δ8.95(s,1H),8.40(s,1H),8.35(s,1H),8.14–8.07(m,2H),8.04(s,4H),7.90(d,J=8.4Hz,2H),7.52–7.43(m,4H),7.36–7.28(m,4H),7.24–7.13(m,4H).

[0053] Example 2

[0054] 1 mol of 4,4'-difluorobenzophenone, 1 mol of phenoxazine, and 1 mol of benzimidazole were added to 8 ml of dimethylformamide solvent, and 3 mol of potassium carbonate was added simultaneously. The reaction mixture was heated to 100 °C and stirred for 20 hours. After the reaction was completed, heating was stopped and the mixture was cooled to room temperature.

[0055] Subsequently, a large amount of distilled water was added to the cooled reaction solution to form a yellow solid, which was then filtered. Dichloromethane was added multiple times to extract the yellow solid, and liquid separation was carried out separately. This extraction-liquid separation step was repeated three times. The organic phases were combined and dried over anhydrous sodium sulfate. Then, purification was carried out by column chromatography. During chromatography, the eluent was a mixture of petroleum ether and ethyl acetate with a volume ratio of 1:3. After chromatography, the target compound, i.e., the thermally activated delayed fluorescence material, was obtained.

[0056] The 1H NMR spectrum of the thermally activated delayed fluorescence material is as Figure 2 shown, and the NMR data are as follows: 11H NMR (500 MHz, DMSO-d6) δ 8.91 (s, 1H), 8.36 (s, 1H), 8.31 (s, 1H), 8.10–8.03 (m, 2H), 8.00 (s, 4H), 7.86 (d, J = 8.4 Hz, 2H), 7.49–7.40 (m, 4H), 7.32–7.24 (m, 4H), 7.20–7.09 (m, 4H).

[0057] Comparative Example 1

[0058] 1 mol of 4,4'-difluorobenzophenone and 1 mol of phenothiazine were added to 10 ml of dimethylformamide solvent, and 3 mol of potassium carbonate was added simultaneously. The reaction mixture was heated to 80 °C and stirred for 12 hours. After the reaction was completed, heating was stopped and it was cooled to room temperature.

[0059] Subsequently, a large amount of distilled water was added to the cooled reaction solution to form a solid, which was filtered. Then, dichloromethane was added multiple times to extract the solid, and liquid separation was carried out separately. This extraction-liquid separation step was repeated three times. The organic phases were combined and dried over anhydrous sodium sulfate. Then, it was separated and purified by a chromatography column. During chromatography, the eluent was petroleum ether and ethyl acetate with a volume ratio of 1:5. After chromatography, the target compound, namely the thermally activated delayed fluorescence material, was obtained.

[0060] The 1H NMR spectrum of the thermally activated delayed fluorescence material is as Figure 3 shown, and the NMR data is 1 1H NMR (500 MHz, DMSO-d) 8 7.83-7.78 (m, 2H), 7.78-7.72 (m, 2H), 7.71-7.63 (m, 1H), 7.56 (t, J = 7.7 Hz, 2H), 7.43 (dd, J = 7.7, 1.5 Hz, 2H), 7.32-7.24 (m, 4H), 7.18 (td, J = 7.6, 1.3 Hz, 2H), 7.09 (dd, J = 8.1, 1.3 Hz, 2H).

[0061] Comparative Example 2

[0062] 1 mol of 4,4'-difluorobenzophenone and 1 mol of 1H-naphtho[2,3-d]imidazole were added to 10 ml of dimethylformamide solvent, and 3 mol of potassium carbonate was added simultaneously. The reaction mixture was heated to 80 °C and stirred for 12 hours. After the reaction was completed, heating was stopped and it was cooled to room temperature.

[0063] Subsequently, a large amount of distilled water was added to the cooled reaction solution to form a solid. Then, dichloromethane was added multiple times to extract the solid, and liquid separation was carried out separately. This extraction-liquid separation step was repeated three times. The organic phases were combined and dried with anhydrous sodium sulfate. Then, purification was carried out by column chromatography. During chromatography, the eluent was petroleum ether and ethyl acetate with a volume ratio of 1:5. After chromatography, the target compound, namely the thermally activated delayed fluorescence material, was obtained.

[0064] The 1H NMR spectrum of the thermally activated delayed fluorescence material is as Figure 4 shown, and the NMR data are 1 H NMR(500MHz,DMSO-d)68.96(s,1H),8.40(s,1H),8.36(s,1H),8.14-8.07(m,2H)8.07-8.01(m,3H),7.91-7.82(m,2H),7.78-7.71(m,1H).7.64(t,J=7.7Hz,2H),7.53-7.44(m,2H).

[0065] Performance Test

[0066] The thermally activated delayed fluorescence material in Example 1 was dissolved in several aqueous solutions of THF (tetrahydrofuran) to prepare test solutions. The concentration of the thermally activated delayed fluorescence material in several test solutions was 10 -5 M, and the volume fractions of water were 0%, 20%, 40%, 60%, 80% and 95% respectively. Under the irradiation of a 365 nm laser, the luminescence characteristics of the thermally activated delayed fluorescence material could be observed, as specifically shown in Figure 5 shown, Figure 5 where the abscissa is the wavelength and the ordinate is the intensity. At the same time, the fluorescence test results showed a significant aggregation-induced emission enhancement effect, and this effect reached the maximum when the volume fraction of the aqueous phase reached 95%, as specifically shown in Figure 6 shown.

[0067] The thermally activated delayed fluorescence materials in Example 1 and Comparative Example 1 were respectively dissolved in THF (tetrahydrofuran). The concentration of the thermally activated delayed fluorescence material was 10 -5 M. Then, the temperature was changed and the emission spectral lifetime of the solution was measured, as specifically shown in Figure 7 and Figure 8 shown, Figure 7 and Figure 8 where the abscissa is time and the ordinate is the photon count, that is, the fluorescence intensity. It can be seen from Figure 7 that as the temperature increases, the emission spectral lifetime of the thermally activated delayed fluorescence material in Example 1 gradually increases, showing obvious TADF characteristics. And combined with Figure 8, the fluorescence lifetime of the thermally activated delayed fluorescence material in Comparative Example 1 is shorter than that in Example 1, and the performance is poorer. Therefore, the thermally activated delayed fluorescence material in the embodiment of the present invention has better thermally activated delayed fluorescence characteristics and aggregation-induced emission enhancement effect.

[0068] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

[0069] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A thermally activated delayed fluorescent material, characterized in that: Its general formula is shown in Formula I: Wherein, X is O or S, and R is a benzimidazole group, an indole group, a 1,2,3,4-tetrahydroisoquinoline group, or a 1H-naphtho[2,3-D]imidazole group.

2. The method for preparing a thermally activated delayed fluorescent material according to claim 1, characterized in that: include: Add halogenated benzophenone, phenazine and donor corresponding to the R group into an organic solvent, add a base, react at 80°C to 100°C for 12h to 24h, and cool to room temperature after the reaction; Add sufficient water to the reaction solution to obtain a solid phase substance, then use an extractant to extract the solid phase substance, separate the liquid, and collect the organic phase; The organic phase is dried, separated and purified to obtain a thermally activated delayed fluorescent material.

3. The method for preparing the thermally activated delayed fluorescent material according to claim 2, characterized in that: The molar ratio of the halogenated benzophenone, the phenazine substance, the donor substance corresponding to the R group and the base is (1-2):(1-2):(1-2):(2-5).

4. The method for preparing a thermally activated delayed fluorescent material according to claim 2, characterized in that: The organic solvent is DMF or DMSO, and the amount of the organic solvent used is 5 to 10 mL based on 1 mol of the halogenated benzophenone.

5. The method for preparing the thermally activated delayed fluorescent material according to claim 2, characterized in that: The halogenated benzophenone is 4,4'-difluorobenzophenone or 4,4'-dibromobenzophenone.

6. The method for preparing a thermally activated delayed fluorescent material according to claim 2, characterized in that: The phenazine substance is phenothiazine or phenoxazine.

7. The method for preparing a thermally activated delayed fluorescent material according to claim 2, characterized in that: The donor substance corresponding to the R group is benzimidazole, indole, 1,2,3,4-tetrahydroisoquinoline or 1H-naphtho[2,3-D]imidazole.

8. The method for preparing a thermally activated delayed fluorescent material according to claim 2, characterized in that: The base is Na2CO3 or K2CO3 or NaH.

9. The method for preparing a thermally activated delayed fluorescent material according to claim 2, characterized in that: The separation and purification operation is to pass the dried organic phase through a chromatography column, and the eluent used in the chromatography is petroleum ether and ethyl acetate in a volume ratio of 1: (3-5).

10. Use of the thermally activated delayed fluorescent material according to claim 1 or the thermally activated delayed fluorescent material prepared by the method for preparing the thermally activated delayed fluorescent material according to any one of claims 2 to 9 in the fields of bio-labeling, bio-imaging and bio-sensing.

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