Preparation method and application of halogenated 2, 1, 3-benzochalcodiazole heat exciton type organic blue light molecule

Abstract

The invention discloses a preparation method and application of halogenated 2, 1, 3-benzochalcodiazole heat exciton type organic blue-light molecules, 2, 1, 3-benzochalcodiazole is used as a parent, corresponding boric acid and a halogenated acceptor are coupled in a mixed solvent of tetrahydrofuran and water through Suzuki coupling reaction under the action of a palladium catalyst, and the halogenated 2, 1, 3-benzochalcodiazole heat exciton type organic blue-light molecules are obtained. And purifying to obtain a target product. The molecules show obvious hybridization localization and charge transfer properties, a high triplet state exciton utilization rate is realized through a high-energy state reverse intersystem crossing process, and meanwhile, by introducing heavy atoms, spin-orbit coupling is effectively enhanced, and the absorption capacity on high-energy radiation is improved; therefore, the compound has the outstanding advantages of ultra-short fluorescence lifetime and high radioluminescence efficiency, and a new solution is provided for developing a new generation of organic luminescent materials with ultra-short lifetime, high efficiency and low cost.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, specifically to a method for preparing and applying halogenated 2,1,3-benzothiodiazole-type thermal exciton organic blue light molecules. Background Technology

[0002] Modern radiation detection systems, such as X-ray imaging, nuclear medicine, and high-energy physics experiments, widely employ photodetectors such as photodiodes or silicon photomultiplier tubes. These detectors exhibit the highest photon detection efficiency in the blue-green light band of 400 to 500 nanometers; therefore, developing materials with highly efficient light-emitting properties in this band is crucial.

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

[0004] However, traditional organic fluorescent dyes can only effectively utilize singlet excitons (25%), resulting in low exciton utilization, which severely limits the luminescence efficiency of the materials. To overcome this limitation, researchers have attempted to use phosphorescent materials and thermally activated delayed fluorescence (TADF) materials to effectively utilize triplet excitons (75%), but these typically exhibit long lifetimes. HLCT materials, on the other hand, facilitate efficient recovery of high-energy triplet excitons through rapid reverse systematic cross-linking (RISC), thereby generating nanosecond-level fluorescence lifetimes, making them more suitable for practical applications requiring rapid scintillation and high temporal resolution.

[0005] In recent years, thermal exciton materials with hybrid localization and charge transfer properties have provided a new approach to resolving this contradiction. These materials can efficiently recover triplet excitons to singlet states and emit light through a high-energy reverse intersystem crossing process, thus achieving high exciton utilization while maintaining ultrafast fluorescence decay on the nanosecond scale. Furthermore, introducing heavy atoms such as chlorine and bromine into the molecular structure is a key strategy to further enhance their performance. The introduction of heavy atoms can enhance the spin-orbit coupling effect of the molecule, thereby accelerating the radiative transition process and shortening the fluorescence lifetime; at the same time, it can also effectively improve the material's ability to block and absorb high-energy rays, ultimately improving its radioluminescence efficiency.

[0006] Therefore, to address the aforementioned problems, this invention provides a method for preparing a halogenated 2,1,3-benzothiodiazole-based thermal exciton-type organic blue light molecule and its application. This method develops a novel organic blue light molecule that combines the advantages of ultrafast decay, high exciton utilization, high radiation absorption efficiency, and low cost. This is of great significance for promoting the development of next-generation high-performance scintillator materials and broadening their practical applications in optoelectronic and radiation detection fields. Summary of the Invention

[0007] The purpose of this invention is to address the problem of low exciton utilization in existing organic blue light-emitting materials by providing a method for preparing and applying a halogenated 2,1,3-benzothiodiazazole-based thermally exciton-type organic blue light-emitting molecule. This novel organic blue light-emitting molecule, based on benzothiodiazazoles, cleverly circumvents the speed and cost bottlenecks of phosphorescent materials and the "delay" problem of TADF materials through a charge transfer (HLCT) mechanism, achieving high exciton utilization. Furthermore, by optimizing the molecular structure and balancing the heavy atom effect, efficient and rapid blue light emission is achieved.

[0008] The objective of this invention is achieved through the following technical solution: A halogenated 2,1,3-benzothiodiazole thermoexciton-type organic blue light molecule, with the following general structural formula: Formula I; Formula II; Formula III; In this context, X is independently selected from oxygen, sulfur, and selenium; R1 is independently selected from hydrogen, chlorine, and bromine; and R2 is independently selected from phenyl, halophenyl, naphthyl, halonaphthyl, anthracene, and haloanthrayl.

[0009] Preferably, the halogenated 2,1,3-benzothiodiazole thermoexciton-type organic blue light molecule uses 2,1,3-benzothiodiazole as the parent compound, and X is independently selected from oxygen, sulfur, and selenium.

[0010] Preferably, the halogen substituent in the R2 group is independently selected from fluorine, chlorine or bromine.

[0011] Preferably, the thermal exciton-type organic blue light molecule comprises, but is not limited to, the following compounds: ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; .

[0012] Preferably, the emission wavelength range of the above-mentioned compound is 400-480nm, which belongs to the blue light region.

[0013] Preferably, all of the above-mentioned organic blue light-emitting small molecules possess HLCT properties.

[0014] Preferably, the above-mentioned organic blue light-emitting small molecules are soluble in dichloromethane, toluene, tetrahydrofuran, and N,N′-dimethylformamide, and have solution processability.

[0015] This application also claims a method for preparing the above-mentioned halogenated 2,1,3-benzothiodiazole thermal exciton type organic blue light molecule, comprising 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.

[0016] Preferably, the mixed solvent of the organic solvent and water is a mixed solvent of tetrahydrofuran and water, wherein the volume ratio of tetrahydrofuran to water in the mixed solvent is 3:1.

[0017] Preferably, the temperature of the Suzuki coupling reaction is 70~90°C and the reaction time is 8~24 hours.

[0018] This application also provides an application of the above-mentioned halogenated 2,1,3-benzothio diazole thermal exciton type organic blue light molecule in the fields of optoelectronics, as well as in X-ray imaging, nuclear radiation monitoring, or high-energy physics detection.

[0019] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art: 1. This invention successfully achieves a 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. It can effectively recover triplet excitons for luminescence through a highly efficient high-energy reverse intersystem crossing (hRISC) process, thereby breaking through the 25% exciton utilization limit of traditional fluorescent materials while maintaining a nanosecond-level ultrashort fluorescence lifetime. This characteristic makes the material irreplaceable in applications requiring fast response and high temporal resolution. 2. The introduction of the heavy atom strategy in this invention plays a key role in achieving two goals at once. The systematic introduction of heavy atoms such as chlorine and bromine into the molecular matrix 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 ray excitation. 3. The molecular structure of this invention provides high tunability and excellent comprehensive performance; by flexibly selecting and combining the chalcogen element X, the halogen substituent R1 and the aryl group R2, the emission wavelength, energy level structure and solid-state stacking 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. 4. This invention opens up a new path for low-cost, high-performance organic scintillator materials; the synthetic route adopted is based on the mature palladium-catalyzed Suzuki coupling reaction, with readily available raw materials and simple steps, which is conducive to large-scale preparation; this breaks through the bottleneck of high cost of traditional inorganic scintillators or noble metal complex phosphorescent materials, and lays a solid material foundation for the development of a new generation of low-cost, high-efficiency radiation detection and imaging equipment. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, some of the drawings in the following description are some embodiments of the present invention. For those skilled in the art, other drawings can be made based on these drawings without creative effort.

[0021] Figure 1This is the proton NMR spectrum of 4Br7P-O prepared in Example 1 of this invention in CDCl3; Figure 2 This is the proton NMR spectrum of 4Br7P-S prepared in DMSO according to Example 1 of this invention; Figure 3 These are the ultraviolet absorption spectra of 4Br7P-O prepared in Example 1 and 4Br7P-S prepared in Example 2 of this invention in different solvents. Figure 4 These are the emission spectra of 4Br7P-O prepared in Example 1 and 4Br7P-S prepared in Example 2 of this invention in different solvents. Figure 5 This is a diagram showing the Stokes shift and solvent orientation polarization relationship of 4Br7P-O prepared in Example 1 and 4Br7P-S prepared in Example 2 of this invention. Figure 6 These are fluorescence lifetime diagrams of 4Br7P-O prepared in Example 1 and 4Br7P-S prepared in Example 2 of this invention in different polar solvents. Figure 7 These are the radioluminescence spectra of 4Br7P-O prepared in Example 1 and 4Br7P-S prepared in Example 2 of this invention under X-rays. Figure 8 This is a CIE colorimetric coordinate diagram of 4Br7P-O prepared in Example 1 and 4Br7P-S prepared in Example 2 of the present invention in toluene solution. Detailed Implementation

[0022] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific implementation schemes are now described in detail.

[0023] The present invention will be further described below with reference to embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0024] Example 1 See appendix Figure 1 - Appendix Figure 8 This embodiment provides a method for preparing a halogenated 2,1,3-benzothiodiazole thermoexciton-type organic blue light molecule, which specifically includes the following steps: Synthesis of dye 4Br7P-O: ; In a 50 mL round-bottom flask, phenylboronic acid (610 mg, 5 mmol, 1 eq), 4,7-dibromo-2,1,3-benzoxadiazole (1.38 g, 5 mmol, 1 eq), tetraphenylphosphine palladium (115 mg, 5% eq), potassium carbonate (3.45 g, 25 mmol, 5 eq), 30 mL of tetrahydrofuran, and 10 mL of deionized water were added. The mixture was reacted under nitrogen protection for 12 hours to obtain a crude product. After extraction and distillation, the crude product was purified by column chromatography (PE:DCM = 50:1) to obtain a pure product as a white solid (742 mg, yield 54%).

[0025] 1 HNMR(400MHz,Chloroform-d)δ7.98–7.90(m,2H),7.71(d,J=7.4Hz,1H),7.55–7.43(m,4H).

[0026] Example 2 See appendix Figure 3 - Appendix Figure 8 This embodiment provides a method for preparing a halogenated 2,1,3-benzothiodiazole thermoexciton-type organic blue light molecule, which specifically includes the following steps: Synthesis of dye 4Br7P-S: ; In a 50 mL round-bottom flask, phenylboronic acid (610 mg, 5 mmol, 1 eq), 4,7-dibromo-2,1,3-benzothiazole (1.47 g, 5 mmol, 1 eq), tetraphenylphosphine palladium (115 mg, 5% eq), potassium carbonate (3.45 g, 25 mmol, 5 eq), 30 mL of tetrahydrofuran, and 10 mL of deionized water were added. The mixture was reacted under nitrogen protection for 12 hours to obtain a crude product. After extraction and distillation, the crude product was purified by column chromatography (PE:DCM = 100:1) to obtain a pure product as a white solid (650 mg, yield 45%).

[0027] 1 HNMR (600MHz, DMSO-d6) δ8.13(d,J=7.6Hz,1H),7.95(d,J=7.0Hz,2H),7.78(d,J=7.5Hz,1H),7.56(t,J=7.6Hz,2H),7.49(t,J=7.4Hz,1H).

[0028] UV-Vis absorption spectroscopy test: Accurately measure 3 mL of Tol or other organic solvents (any one of DBE, CB, EA, THF, DCM, ACN, DMSO, IPA) into a 1 cm × 1 cm quartz cuvette and record the baseline. Accurately add 30 μL of the 4Br7P-O stock solution to the cuvette, shake well, and prepare corresponding working solutions with a concentration of 10 μmol / L. Record the UV-Vis absorption spectra of the corresponding compounds. Similarly, after recording the baseline of the Tol solution, record the UV-Vis absorption spectrum of the initial working solution using a UV-Vis spectrophotometer. Figure 3 As shown, the UV-Vis absorption spectrum remains essentially unchanged when the solvent changes from low polarity Tol to high polarity IPA, indicating that the absorption spectrum is extremely insensitive to solvent polarity. This suggests that the change in the dipole moment of the molecule is very small during the process of electrons being excited from the ground state (S0) to the excited state (S1), which is a typical characteristic of locally excited states (LE).

[0029] Fluorescence emission spectroscopy test: Accurately measure 3 mL of Tol or other organic solvents (any one of DBE, CB, EA, THF, DCM, ACN, DMSO, IPA) into a 1 cm × 1 cm quartz cuvette. Accurately add 30 μL of the stock solution of compound 4Br7P-O to the cuvette, shake well, and prepare corresponding working solutions with a concentration of 10 μmol / L. Record the fluorescence emission spectra of the corresponding compounds. Figure 4 As shown, with increasing solvent polarity, the PL spectrum exhibits a significant solvent-induced red shift, revealing a large dipole moment difference between the luminescent excited state (S1) and the ground state (S0). The polar solvent stabilizes this excited state with a large dipole moment, lowering its energy, which is clear evidence of charge-transfer excited states (CT).

[0030] Figure 5 The Stokes shift versus solvent orientation polarization relationship for 4Br7P-O and 4Br7P-S is plotted using the Lippert-Mataga model, showing the Stokes shift (va-vf) versus solvent orientation polarizability (Δf). Figure 5 As shown, two linear fitting lines with different slopes were obtained. The line with the smaller slope represents the LE excited state component with a smaller dipole moment, while the line with the larger slope represents the CT excited state component with a larger dipole moment. This indicates that its 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 states.

[0031] Fluorescence lifetime testing: Low-polarity Tol, medium-polarity THF, and high-polarity IPA were selected as solvents to test the fluorescence lifetime of 4Br7P-O and 4Br7P-S in these solvents. Figure 6As shown, they all exhibit nanosecond-level single exponential decay and a gradual increase in lifetime with increasing solvent polarity, consistent with the characteristics of the HLCT state.

[0032] Radiative emission spectra: The radiative emission spectra of 4Br7P-O and 4Br7P-S were tested respectively and compared with anthracene (An). They showed excellent luminescence properties, and the luminescence in both solution and aggregated state was in the range of 400-500nm. They also showed good compatibility with silicon photomultiplier tubes.

[0033] In summary, this invention successfully achieves a 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, enabling efficient recovery of triplet excitons for luminescence via a highly efficient high-energy reverse intersystem crossing process. This breaks through the 25% exciton utilization limit of traditional fluorescent materials while maintaining a nanosecond-level ultrashort fluorescence lifetime. This characteristic makes the material irreplaceable in applications requiring rapid response and high temporal resolution. The introduction of the heavy atom strategy in this invention plays a crucial "two birds with one stone" role. Systematically introducing heavy atoms such as chlorine and bromine into the molecular matrix 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 significantly improving fluorescence efficiency. This invention improves the radioluminescence efficiency under high-energy radiation excitation; its molecular structure provides high tunability and excellent comprehensive performance; through flexible selection and combination of chalcogenide X, halogen substituent R1, and aryl group R2, the emission wavelength, energy level structure, and solid-state stacking behavior of the material can be finely controlled on a unified molecular platform, providing broad space for performance optimization and meeting the needs of different application scenarios; this invention opens up a new path for low-cost, high-performance organic scintillator materials; the synthetic route adopted is based on the mature palladium-catalyzed Suzuki coupling reaction, with readily available raw materials and simple steps, which is conducive to large-scale preparation; this breaks through the bottleneck of high cost of traditional inorganic scintillators or noble metal complex phosphorescent materials, laying a solid material foundation for the development of a new generation of low-cost, high-efficiency radiation detection and imaging equipment.

[0034] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A halogenated 2,1,3-benzothio diazole thermoexciton-type organic blue light molecule, characterized in that, The general formula of organic blue light molecules is as follows: Formula I; Formula II; Formula III; In this context, X is independently selected from oxygen, sulfur, and selenium; R1 is independently selected from hydrogen, chlorine, and bromine; and R2 is independently selected from phenyl, halophenyl, naphthyl, halonaphthyl, anthracene, and haloanthrayl.

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

3. The halogenated 2,1,3-benzothio diazole thermoexciton-type organic blue light molecule according to claim 1, characterized in that, The halogen substituents in the R2 group are independently selected from fluorine, chlorine, or bromine.

4. The halogenated 2,1,3-benzothio diazole thermoexciton-type organic blue light molecule according to claim 1, characterized in that, The thermal exciton-type organic blue light molecule includes, but is not limited to, the following compounds: ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； 。 5. A method for preparing a halogenated 2,1,3-benzothiodiazole thermoexciton-type organic blue light molecule as described in any one of claims 1 to 4, characterized in that, 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 method for preparing the halogenated 2,1,3-benzothio diazole thermal exciton type organic blue light molecule according to claim 5, 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 method for preparing the halogenated 2,1,3-benzothiodiazole thermoexciton-type organic blue light molecule according to claim 5, characterized in that, The Suzuki coupling reaction is carried out at a temperature of 70-90°C for 8-24 hours.

8. The application of a halogenated 2,1,3-benzothiodiazole thermoexciton-type organic blue light molecule prepared by the method of any one of claims 1 to 4 or the method of any one of claims 5 to 7 in the optoelectronic field and in X-ray imaging, nuclear radiation monitoring or high-energy physics detection.

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