Preparation method and application of halogenated 2,1,3-benzothiazole hot exciton type organic blue light molecules

Abstract

The application discloses a preparation method and application of a halogenated 2,1,3-benzothiadi-azolyl blue light molecule, and the method comprises the following steps: taking 2,1,3-benzothiadi-azolyl as a parent body, and coupling corresponding boric acid and a halogenated acceptor in a mixed solvent of tetrahydrofuran and water under the action of a palladium catalyst to obtain a target product after purification. The molecule shows obvious hybridization and charge transfer properties, realizes high triplet exciton utilization rate through a high-energy state reverse intersystem crossing process, effectively enhances spin-orbital coupling by introducing heavy atoms, and improves the absorption capacity to high-energy radiation, so that the molecule has the outstanding advantages of super-short fluorescent lifetime and high photoluminescence efficiency, and provides a new solution for developing a new generation of organic luminescent materials with super-short lifetime, high efficiency and low cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of light-emitting materials, in particular to a preparation method and application of halogenated 2,1,3-benzothiadi-azolyl hot-exciton type organic blue light molecules. BACKGROUND

[0002] Modern radiation detection systems, such as X-ray imaging, nuclear medicine and high-energy physics experiments, widely use photodiodes or silicon photomultiplier tubes and other photoelectric detectors. These detectors have the highest photon detection efficiency in the blue-green light band of 400-500 nm, so it is crucial to develop materials with high-efficiency light-emitting properties in this band.

[0003] Organic blue light molecules have become a research hotspot for the next generation of light-emitting materials due to their flexible structure, low preparation cost, easy large-area preparation, and fast fluorescence decay rate, and have shown great application potential in the field of radiation detection.

[0004] However, traditional organic fluorescent dyes can only effectively utilize singlet excitons (25%), and the exciton utilization rate is low, which severely limits the light-emitting efficiency of the material. In order to break through this limitation, researchers try to use phosphorescent materials and thermally activated delayed fluorescence (TADF) materials to effectively utilize triplet excitons (75%), but they usually exhibit long lifetimes. HLCT materials help to efficiently recycle high-energy triplet excitons through fast reverse intersystem crossing (RISC) to produce nanosecond fluorescence lifetimes, which are more suitable for practical applications that require fast scintillation and high temporal resolution.

[0005] In recent years, hot-exciton materials with hybrid localized and charge transfer characteristics have provided a new way to solve this contradiction. This type of material can efficiently recycle triplet excitons to singlet states and emit light through the reverse intersystem crossing process of high-energy states, thereby achieving high exciton utilization efficiency while maintaining nanosecond ultrafast fluorescence decay. In addition, the introduction of heavy atoms such as chlorine and bromine in the molecular structure is a key strategy to further improve its performance. The introduction of heavy atoms can enhance the spin-orbit coupling effect of the molecule, thereby accelerating the radiation transition process and shortening the fluorescence lifetime; at the same time, it can also effectively improve the blocking and absorption ability of high-energy radiation of the material, ultimately improving its radioluminescence efficiency.

[0006] Therefore, in view of the above problems, the present application provides a preparation method and application of halogenated 2,1,3-benzothiadi-azolyl hot-exciton type organic blue light molecules, which develops a new type of organic blue light molecule with comprehensive advantages such as ultrafast decay, high exciton utilization rate, high radiation absorption efficiency and low cost, which is of great significance for promoting the development of the next generation of high-performance scintillator materials and broadening its practical application in the fields of optoelectronics and radiation detection. SUMMARY

[0007] The present application aims at the low utilization rate of existing organic blue excitons, and provides a preparation method and application of a halogenated 2,1,3-benzothiadi-azol-based thermal exciton type organic blue molecule, and a new type of organic blue molecule based on benzothiadi-azol, which cleverly avoids the speed and cost bottleneck of phosphorescent materials and the "delay" problem of TADF materials through the charge transfer (HLCT) mechanism, and realizes high-efficiency exciton utilization. On the other hand, through optimization of the molecular structure, balance of heavy atom effect, and realization of efficient and rapid blue light emission.

[0008] The object of the present application is achieved by the following technical solutions.

[0009] A halogenated 2,1,3-benzothiadi-azol-based thermal exciton type organic blue molecule, and the structure general formula of the organic blue molecule is as follows:

[0010] Formula I; Formula II; Formula III;

[0011] wherein X is independently selected from oxygen, sulfur, selenium; R1 is independently selected from hydrogen, chlorine, bromine; R2 is independently selected from phenyl, halogenated phenyl, naphthyl, halogenated naphthyl, anthracene, halogenated anthracene.

[0012] Preferably, the halogenated 2,1,3-benzothiadi-azol-based thermal exciton type organic blue molecule takes 2,1,3-benzothiadi-azol as a parent molecule, and X is independently selected from oxygen, sulfur and selenium.

[0013] Preferably, the halogen in the R2 group is independently selected from fluorine, chlorine or bromine.

[0014] Preferably, the thermal exciton type organic blue molecule comprises, but is not limited to, the following compounds:

[0015] ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;

[0016] ;

[0017]

[0018] Preferably, the emission wavelength of the above-mentioned compound ranges from 400 to 480 nm, belonging to the blue light region.

[0019] Preferably, the above-mentioned organic blue light small molecules all have the HLCT property.

[0020] Preferably, the above-mentioned organic blue light small molecules are soluble in dichloromethane, toluene, tetrahydrofuran and N,N'-dimethylformamide, and have the solution processability.

[0021] The application also claims a preparation method of the above-mentioned halogenated 2,1,3-benzosulfur heterodiazole hot exciton type organic blue light molecule, comprising the following steps:

[0022] Under the catalysis of a palladium catalyst, one of phenylboronic acid, naphthylboronic acid or anthrylboronic acid is connected with a halogenated 2,1,3-sulfur heterodiazole acceptor through Suzuki coupling reaction in a mixed solvent of an organic solvent and water as a reaction medium; after the reaction is completed, the obtained crude product is separated and purified by silica gel column chromatography, so as to obtain the halogenated 2,1,3-benzosulfur heterodiazole hot exciton type organic blue light molecule.

[0023] ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Preferably, the mixed solvent of the organic solvent and water is a mixed solvent of tetrahydrofuran and water, and the volume ratio of tetrahydrofuran to water in the mixed solvent is 3:1.

[0024] Preferably, the temperature of the Suzuki coupling reaction is 70-90 DEG C, and the reaction time is 8-24 hours.

[0025] The application also provides application of the above halogenated 2,1,3-benzothiadi-azole hot-exciton type organic blue light molecule in the field of optoelectronics, X-ray imaging, nuclear radiation monitoring or high-energy physics detection.

[0026] Thanks to the above technical solution, the application has the following beneficial effects compared with the prior art:

[0027] 1. The application successfully realizes perfect combination of ultrafast fluorescence decay and high exciton utilization rate; through ingenious molecular design, the developed material exhibits distinct hybridization localization and charge transfer characteristics, can effectively recycle triplet excitons for light emission through efficient high-energy state reverse intersystem crossing (hRISC) process, thereby breaking through the 25% exciton utilization rate limit of traditional fluorescent materials while maintaining nanosecond-level ultra-short fluorescence lifetime; this characteristic makes the material irreplaceable in applications requiring fast response and high time resolution;

[0028] 2. The introduction of heavy atom strategy plays a key role in achieving two goals with one stone; the introduction of heavy atoms such as chlorine and bromine in the molecular parent body not only significantly enhances the spin-orbit coupling effect of the molecule, thereby further shortening the fluorescence lifetime, but also effectively improves the overall absorption and blocking capacity of the material to high-energy radiation, ultimately greatly improving the radiation-induced luminescence efficiency under high-energy radiation excitation;

[0029] 3. The molecular structure of the application provides high adjustability and excellent comprehensive performance; through flexible selection and combination of chalcogen element X, halogen substituent R1 and aryl group R2, the luminescence wavelength, energy level structure and solid-state packing behavior of the material can be finely controlled on a unified molecular platform, which provides a broad space for performance optimization and meeting the needs of different application scenarios;

[0030] 4. The application opens up a new path for low-cost, high-performance organic scintillator materials; the synthetic route adopted takes the mature palladium-catalyzed Suzuki coupling reaction as the core, the raw materials are easy to obtain, and the steps are simple, which is conducive to large-scale preparation; this breaks the bottleneck of high cost of traditional inorganic scintillators or noble metal complex phosphorescent materials, and lays a solid material foundation for developing a new generation of low-cost, high-efficiency radiation detection and imaging equipment. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the drawings needed to be used in the description of the specific embodiments or the prior art will be briefly introduced. Obviously, some of the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0032] Figure 1 is the hydrogen spectrum of 4Br7P-O prepared in Example 1 of the present application in CDCl3;

[0033] Figure 2 is the hydrogen spectrum of 4Br7P-S prepared in Example 1 of the present application in DMSO;

[0034] Figure 3 is the ultraviolet absorption spectrum of 4Br7P-O prepared in Example 1 of the present application and 4Br7P-S prepared in Example 2 in different solvents;

[0035] Figure 4 is the emission spectrum of 4Br7P-O prepared in Example 1 of the present application and 4Br7P-S prepared in Example 2 in different solvents;

[0036] Figure 5 is the Stokes shift and solvent orientation polarization relationship diagram of 4Br7P-O prepared in Example 1 of the present application and 4Br7P-S prepared in Example 2;

[0037] Figure 6 is the fluorescence lifetime diagram of 4Br7P-O prepared in Example 1 of the present application and 4Br7P-S prepared in Example 2 in different polar solvents;

[0038] Figure 7 is the radioluminescence spectrum of 4Br7P-O prepared in Example 1 of the present application and 4Br7P-S prepared in Example 2 under X-ray;

[0039] Figure 8 is the CIE chromaticity coordinate diagram of 4Br7P-O prepared in Example 1 of the present application and 4Br7P-S prepared in Example 2 in toluene solution. DETAILED DESCRIPTION

[0040] In order to have a more clear understanding of the technical features, objectives and effects of the present application, the specific embodiments will be described in detail.

[0041] The application will be further described in connection with the following examples without being limited to the following examples. The implementation conditions used in the examples can be further adjusted according to different requirements of specific use, and the implementation conditions marked are conventional conditions in the industry. The technical features involved in each embodiment of the application can be combined with each other as long as they do not constitute a conflict.

[0042] Example 1

[0043] Referring to the accompanying Figure 1 -attached Figure 8 The embodiment provides a preparation method of a halogenated 2,1,3-benzothiadi- azole hot exciton type organic blue light molecule, and specifically comprises the following steps:

[0044] Synthesis of dye 4Br7P-O:

[0045] ;

[0046] In a 50ml round-bottom flask, benzene boronic acid (610mg, 5mmol, 1eq), 4,7-dibromo-2,1,3-benzothiadiazole (1.38g, 5mmol, 1eq) and tetrakis triphenyl phosphine palladium (115mg, 5%eq), potassium carbonate (3.45g, 25mmol, 5eq), tetrahydrofuran 30mL and 10mL deionized water were added, and the reaction was carried out under nitrogen protection for 12 hours to obtain a crude product. After extraction and distillation, the pure product was obtained by column chromatography (PE:DCM=50:1) as a white solid (742mg, yield 54%).

[0047] 1 HNMR (400 MHz, Chloroform-d) δ 7.98-7.90 (m, 2H), 7.71 (d, J=7.4 Hz, 1H), 7.55-7.43 (m, 4H).

[0048] Example 2

[0049] Referring to the accompanying Figure 3 -attached Figure 8 The embodiment provides a preparation method of a halogenated 2,1,3-benzothiadi- azole hot exciton type organic blue light molecule, and specifically comprises the following steps:

[0050] Synthesis of dye 4Br7P-S:

[0051] ;

[0052] In a 50 mL round bottom flask, add phenylboronic acid (610 mg, 5 mmol, 1 eq), 4,7-dibromo-2,1,3-benzothiazole (1.47 g, 5 mmol, 1 eq) and tetrakis(triphenylphosphine)palladium (115 mg, 5% eq), potassium carbonate (3.45 g, 25 mmol, 5 eq), tetrahydrofuran 30 mL and 10 mL deionized water, under nitrogen protection for 12 hours to get the crude product, after extraction and distillation, the pure product is obtained as a white solid (650 mg, yield 45%) by column chromatography (PE:DCM = 100:1).

[0053] 1 HNMR (600 MHz, DMSO-d6) δ 8.13 (d, J = 7.6 Hz, 1H), 7.95 (d, J = 7.0 Hz, 2H), 7.78 (d, J = 7.5 Hz, 1H), 7.56 (t, J = 7.6 Hz, 2H), 7.49 (t, J = 7.4 Hz, 1H).

[0054] UV-Vis absorption spectrum test: accurately take 3 mL of Tol or other organic solvents (any one of DBE, CB, EA, THF, DCM, ACN, DMSO, IPA) in a 1 cm x 1 cm quartz cuvette, record the baseline. Accurately add 30 μL of compound 4Br7P-O mother liquor to the cuvette, shake evenly and prepare the corresponding working solution with a concentration of 10 μmol / L, respectively, and record the UV-Vis absorption spectrum of the corresponding compound. Similarly, after recording the baseline of the Tol solution, the UV-Vis absorption spectrum of the test working solution is recorded by the UV-Vis spectrophotometer. As shown in Figure 3 the UV-Vis absorption spectrum remains basically unchanged when the solvent changes from low polarity Tol to high polarity IPA, and the absorption spectrum is not very sensitive to solvent polarity. This indicates that the dipole moment of the molecule changes very little in the process of exciting electrons from the ground state (S0) to the excited state (S1), which is a typical feature of the local excited state (LE).

[0055] Fluorescence emission spectrum test: accurately take 3 mL of Tol or other organic solvents (any one of DBE, CB, EA, THF, DCM, ACN, DMSO, IPA) in a 1 cm x 1 cm quartz cuvette. Accurately add 30 μL of compound 4Br7P-O mother liquor to the cuvette, shake evenly and prepare the corresponding working solution with a concentration of 10 μmol / L, respectively, and record the fluorescence emission spectrum of the corresponding compound. As shown in Figure 4As shown, PL spectra show obvious solventochromic red shift with the increase of solvent polarity, indicating a large dipole moment difference between the excited state (S1) and the ground state (S0) of the luminescence. Polar solvents stabilize the excited state with large dipole moment and reduce its energy, which is a clear evidence of charge transfer excited state (CT).

[0056] Figure 5 For the Stokes shift of 4Br7P-O, 4Br7P-S and the relationship between solvent orientation polarization, the Stokes shift (va-vf,) is plotted against the orientation polarization of the solvent (Δf) using the Lippert-Mataga model. As shown, Figure 5 Two linear fitting lines with different slopes are obtained, where the line with smaller slope represents the LE excited state component with smaller dipole moment, and the line with larger slope represents the CT excited state component with larger dipole moment. This indicates that the excited state has obvious charge transfer characteristics, but at the same time retains the characteristics of local excitation, which is consistent with the properties of HLCT state.

[0057] Fluorescence lifetime test: Select small polarity Tol, medium polarity THF and large polarity IPA as solvents respectively, and test the fluorescence lifetime of 4Br7P-O, 4Br7P-S in the above solvents. As shown, Figure 6 All show nanosecond single exponential decay and gradually prolonged lifetime with the increase of solvent polarity, which is consistent with the characteristics of HLCT state.

[0058] Radioluminescence spectrum: Test the radioluminescence spectrum of 4Br7P-O, 4Br7P-S respectively, and compare with anthracene (An), which shows excellent luminescent properties, and both solution and aggregation state luminescence are in the range of 400-500 nm, which is well adapted to silicon photomultiplier.

[0059] In summary, the present application successfully realizes the perfect combination of ultrafast fluorescence decay and high exciton utilization; through ingenious molecular design, the developed material exhibits distinct hybridization localization and charge transfer characteristics, and can effectively recycle triplet excitons for luminescence through an efficient high-energy reverse intersystem crossing process, thereby breaking through the 25% exciton utilization limit of traditional fluorescent materials while maintaining nanosecond-level ultra-short fluorescence lifetime; this characteristic makes the material irreplaceable in applications requiring fast response and high time resolution; the introduction of heavy atom strategy plays a key role in "catching two birds with one stone"; the systematic introduction of heavy atoms such as chlorine and bromine in the molecular parent not only significantly enhances the spin-orbit coupling effect of the molecule, thereby further shortening the fluorescence lifetime, but also effectively improves the overall absorption and blocking ability of the material to high-energy radiation, ultimately greatly improving its radioluminescence efficiency under high-energy radiation excitation; the molecular structure of the present application provides high adjustability and excellent comprehensive performance; through flexible selection and combination of chalcogen elements X, halogen substituents R1 and aryl groups R2, the luminescence wavelength, energy level structure and solid-state packing behavior of the material can be finely controlled on a unified molecular platform, providing a broad space for performance optimization and meeting the needs of different application scenarios; the present application opens up a new path for low-cost, high-performance organic scintillator materials; the synthesis route adopted takes the mature palladium-catalyzed Suzuki coupling reaction as the core, the raw materials are easy to obtain, and the steps are simple, which is conducive to large-scale preparation; this breaks the bottleneck of high cost of traditional inorganic scintillators or noble metal complex phosphorescent materials, and lays a solid material foundation for developing a new generation of low-cost, high-efficiency radiation detection and imaging equipment.

[0060] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. The application of a halogenated 2,1,3-benzothio diazole thermal exciton type organic blue light molecule in X-ray imaging; The general structural formula of the halogenated 2,1,3-benzothio diazole thermoexciton-type organic blue light molecule is as follows: Formula I; Formula II; Formula III; in, X is independently selected from oxygen, sulfur, and selenium; R1 is independently selected from hydrogen, chlorine, and bromine; R2 is independently selected from phenyl, halophenyl, naphthyl, halonaphthyl, anthracene, and haloanthrayl.

2. The application of the halogenated 2,1,3-benzothio diazole thermal exciton type organic blue light molecule according to claim 1 in X-ray imaging, characterized in that, Using 2,1,3-benzothiodiazole as the parent compound, X is independently selected from oxygen, sulfur, and selenium.

3. The application of the halogenated 2,1,3-benzothio diazole thermal exciton type organic blue light molecule according to claim 1 in X-ray imaging, characterized in that, The halogen substituents in the R2 group are independently selected from chlorine or bromine.

4. The application of the halogenated 2,1,3-benzothio diazole thermal exciton type organic blue light molecule according to claim 1 in X-ray imaging, characterized in that, The thermal exciton-type organic blue light molecule includes, but is not limited to, the following compounds: ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； 。 5. The application of the halogenated 2,1,3-benzothio diazole thermal exciton type organic blue light molecule according to claim 1 in X-ray imaging, characterized in that, The preparation method of the halogenated 2,1,3-benzothio diazole thermal exciton type organic blue light molecule includes the following steps: In the presence of a palladium catalyst, and using a mixed solvent of organic solvent and water as the reaction medium, one of phenylboronic acid, naphthaleneboronic acid, or anthraquinoneboronic acid is linked to a halogenated 2,1,3-thiodiazazole acceptor via a Suzuki coupling reaction. After the reaction is completed, the crude product is purified by silica gel column chromatography to obtain the halogenated 2,1,3-benzothiodiazazole-based thermal exciton type organic blue light molecule.

6. The application of the halogenated 2,1,3-benzothio diazole thermal exciton type organic blue light molecule according to claim 5 in X-ray imaging, characterized in that, The organic solvent and water mixture is a mixture of tetrahydrofuran and water, wherein the volume ratio of tetrahydrofuran to water in the mixture is 3:

1.

7. The application of the halogenated 2,1,3-benzothio diazole thermal exciton type organic blue light molecule according to claim 5 in X-ray imaging, characterized in that, The Suzuki coupling reaction is carried out at a temperature of 70-90°C for 8-24 hours.

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