Application of dibenzo quinoxaline compound in organic phosphorescent material

Abstract

The invention discloses an application of a dibenzo quinoxaline compound in an organic phosphorescent material. The dibenzo quinoxaline compound has a structural formula as shown in a formula (I), wherein X1 and X2 are respectively and independently selected from H or halogen. The dibenzo quinoxaline compound provided by the invention can show efficient and stable room-temperature phosphorescence emission under various excitation conditions of ultraviolet light, visible light, X-rays and the like. And the organic room-temperature phosphorescent material prepared from the dibenzo quinoxaline compound has excellent thermal stability and shows a long-wave-band phosphorescent emission characteristic. The material can be used for high-precision biological imaging, and can be applied to X-ray imaging as an organic scintillator.

Description

Technical Field

[0001] This invention relates to the field of phosphorescent materials technology, and in particular to the application of a dibenzoquinoxaline compound in organic phosphorescent materials. Background Technology

[0002] Organic room temperature phosphorescence (ORTP) materials have attracted widespread attention due to their potential applications in organic light-emitting diodes (OLEDs), anti-counterfeiting encryption, bioimaging, information storage and detection, and other fields. Compared with traditional inorganic phosphors and heavy metal complexes, pure organic room temperature phosphorescent materials have advantages such as strong designability, abundant sources, environmental friendliness, and low cost. However, achieving efficient and stable phosphorescence emission from pure organic molecules at room temperature still faces challenges, mainly because the spin-orbit coupling of organic molecules is relatively weak, and triplet excitons are susceptible to nonradiative relaxation and molecular motion quenching.

[0003] Current research mainly focuses on enhancing the efficiency and lifetime of room-temperature phosphorescence by suppressing molecular motion and nonradiative processes through molecular design (such as introducing rigid frameworks, hydrogen bonding, and crystallization confinement) or external environmental regulation (such as doping and polymer matrix immobilization). These strategies have made some progress under ultraviolet excitation, and some materials also exhibit phosphorescence emission under visible light excitation. However, most publicly available organic room-temperature phosphorescent systems are limited to single or dual-mode excitation, with limited research on multimode excitation, especially involving high-energy X-ray excitation. In practical applications, single-excitation-mode organic room-temperature phosphorescent materials have certain limitations in functional expansion. For example, ultraviolet light sources may pose potential biosafety risks and insufficient penetration depth; while visible light excitation is safer, its effectiveness is limited in certain detection scenarios requiring high penetration and high spatial resolution; and X-rays, with their high energy and strong penetrating power, can achieve deep detection and imaging, but currently, there is a lack of organic materials that can exhibit stable room-temperature phosphorescence under multiple excitation conditions, including X-rays, ultraviolet light, and visible light.

[0004] Therefore, there is an urgent need to develop a new type of organic room temperature phosphorescent material that can exhibit efficient and stable phosphorescence emission under various excitation conditions such as ultraviolet light, visible light and X-rays, in order to meet the application needs of multiple scenarios and functions. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the first aspect of the present invention proposes the application of a dibenzoquinoxaline compound in organic phosphorescent materials, wherein the dibenzoquinoxaline compound is capable of generating phosphorescence under ultraviolet, visible light and X-ray tri-mode excitation. According to a first aspect of the present invention, an application of a dibenzoquinoxaline compound in an organic phosphorescent material is provided, the dibenzoquinoxaline compound having the structural formula shown in formula (I): ; X1 and X2 are each independently selected from H or halogens.

[0006] According to a preferred embodiment of the present invention, X1 and X2 are the same.

[0007] According to a preferred embodiment of the present invention, X1 and X2 are selected from H, F, Cl, Br, and I.

[0008] According to a preferred embodiment of the present invention, the dibenzoquinoxaline compound is selected from the following structural formulas: .

[0009] According to a preferred embodiment of the present invention, the dibenzoquinoxaline compound is prepared by the following method: Compound 1 and compound 2 are subjected to a condensation reaction to obtain the product; The structural formulas of compound 1 and compound 2 are shown below: .

[0010] According to a preferred embodiment of the present invention, the reaction temperature of the condensation reaction is 110°C to 120°C.

[0011] According to a preferred embodiment of the present invention, the reaction time of the condensation reaction is 8-12 hours.

[0012] According to a preferred embodiment of the present invention, the solvent for the condensation reaction includes at least one of acetic acid, formic acid, and p-toluenesulfonic acid-DMF system.

[0013] According to a preferred embodiment of the present invention, the dibenzoquinoxaline compound produces phosphorescence under excitation by ultraviolet light, visible light, or X-rays.

[0014] According to a preferred embodiment of the present invention, the dibenzoquinoxaline compound is used as an organic phosphorescent material in bioimaging or X-ray imaging.

[0015] The application of the embodiments of the present invention has at least the following beneficial effects: The dibenzoquinoxaline compounds provided by this invention exhibit efficient and stable room-temperature phosphorescence emission under various excitation conditions, including ultraviolet light, visible light, and X-rays. Furthermore, the organic room-temperature phosphorescent materials prepared from these dibenzoquinoxaline compounds possess excellent thermal stability and exhibit long-wavelength phosphorescence emission characteristics. These materials can be used for high-precision biological imaging and can also be applied as organic scintillators in X-ray imaging.

[0016] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is the 1H NMR spectrum of the dibenzoquinoxaline compound prepared in Example 1 of this invention; Figure 2 This is the 1H NMR spectrum of the dibenzoquinoxaline compound prepared in Example 2 of this invention; Figure 3 These are the steady-state and phosphorescence spectra of Embodiments 1 and 2 of the present invention; Figure 4 These are the transient fluorescence spectra of Examples 1 and 2 of the present invention; Figure 5 These are the temperature-varying spectra of Embodiments 1 and 2 of the present invention; Figure 6 These are the excitation spectra of Embodiments 1 and 2 of the present invention; Figure 7 The phosphorescence spectra are those obtained under different excitations in Examples 1 and 2 of the present invention. Figure 8 These are the radiation emission spectra of Embodiments 1 and 2 of the present invention; Figure 9 These are X-ray imaging results of embodiments 1 and 2 of the present invention; Figure 10 These are intermolecular interaction diagrams for Examples 1 and 2 of the present invention. Detailed Implementation

[0018] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0019] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0020] In some embodiments, the present invention provides an application of a dibenzoquinoxaline compound in organic phosphorescent materials, wherein the dibenzoquinoxaline compound has the structural formula shown in formula (I): ; X1 and X2 are each independently selected from H or halogens.

[0021] In this invention, the dibenzoquinoxaline compounds exhibit efficient and stable room-temperature phosphorescence emission under various excitation conditions, including ultraviolet light, visible light, and X-rays. Furthermore, the organic room-temperature phosphorescent materials prepared from the dibenzoquinoxaline compounds of this invention possess excellent thermal stability and exhibit long-wavelength phosphorescence emission characteristics. These materials can be used for high-precision bioimaging and can also be applied as organic scintillators in X-ray imaging.

[0022] In some embodiments, X1 and X2 are the same.

[0023] In some embodiments, X1 and X2 are selected from H, F, Cl, Br, and I.

[0024] In some embodiments, the dibenzoquinoxaline compounds are selected from the following structural formulas: .

[0025] In some embodiments, the dibenzoquinoxaline compounds are prepared by the following method: Compound 1 and compound 2 are subjected to a condensation reaction to obtain the product; The structural formulas of compound 1 and compound 2 are shown below: .

[0026] In some embodiments, the reaction temperature of the condensation reaction is 110°C to 120°C. For example, it includes 110°C, 112°C, 114°C, 116°C, 118°C, 120°C, or any sub-range consisting of two of the above values.

[0027] In this invention, the reaction temperature is within the above-mentioned range, resulting in a more thorough reaction and a higher yield.

[0028] In some embodiments, the reaction time of the condensation reaction is 8 to 12 hours. For example, it includes 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours, or any subrange consisting of two of the above values.

[0029] In this invention, the reaction time is within the above-mentioned range, resulting in a more thorough reaction and a higher yield.

[0030] In some embodiments, the solvent for the condensation reaction includes at least one of acetic acid, formic acid, and p-toluenesulfonic acid-DMF system.

[0031] In some embodiments, the dibenzoquinoxaline compounds produce phosphorescence under excitation by ultraviolet light, visible light, or X-rays.

[0032] In some embodiments, the dibenzoquinoxaline compounds are used as organic phosphorescent materials in bioimaging or X-ray imaging.

[0033] Example 1 This example provides a dibenzoquinoxaline compound, the reaction equation and preparation method of which are as follows:

[0034] 1.00 g (4.89 mmol) of phenanthrenequinone and 0.62 g (5.76 mmol) of diaminomaleonitrile were added to a 250 mL three-necked flask, followed by 150 mL of acetic acid. The mixture was stirred and dissolved under a nitrogen atmosphere and reacted at 120 °C for 10 h. The reaction solution was cooled, and the filtrate was evaporated to dryness using a rotary evaporator. Purification was performed by silica gel column chromatography, using a 1:2 (v / v) mixture of dichloromethane and n-hexane as the eluent. A pale yellow powder (named DCPP) was obtained in 73% yield.

[0035] Its proton spectrum is as follows Figure 1 The NMR data are shown below: 1 H NMR (500 MHz, Chloroform- d ) δ 9.20 (d, J = 8.1 Hz, 2H), 8.66 (d, J =8.3 Hz, 2H), 7.97 (t, J = 7.7 Hz, 2H), 7.85 (t, J = 7.6 Hz, 2H). Example 2 This example provides a dibenzoquinoxaline compound, the reaction equation and preparation method of which are as follows:

[0036] 2,7-Dibromophenanthrenequinone (1.00 g, 2.73 mmol) and diaminomaleitrile (0.35 g, 3.28 mmol) were added to a 250 mL three-necked flask, followed by 150 mL of acetic acid. The mixture was stirred and dissolved under a nitrogen atmosphere and reacted at 120 °C for 10 h. The reaction solution was cooled, and the filtrate was evaporated to dryness using a rotary evaporator. Purification was performed by silica gel column chromatography, using a 1:2 (v / v) mixture of dichloromethane and n-hexane as the eluent. A pale yellow powder product (named DCPPBr) was obtained in 67% yield.

[0037] Its proton spectrum is as follows Figure 2 The NMR data are shown below: 1 H NMR (500 MHz, Chloroform-d) δ 9.05 (d, J = 8.6 Hz, 2H), 8.70 (s, 2H), 7.98 (d, J = 8.6 Hz, 2H). Application examples First, the products obtained in Examples 1 and 2 were recrystallized in a mixed solvent of dichloromethane and n-hexane to obtain crystalline powders of the target compound. Subsequently, steady-state spectroscopy, phosphorescence spectroscopy, and transient fluorescence spectroscopy were performed on the obtained materials, and the results are as follows: Figure 3 and Figure 4 As shown. From Figure 3 As can be seen, the steady-state spectrum of Example 1 (DCPP) shows yellow-green emission, while its phosphorescence spectrum has two emission peaks, with the main emission peak located in the range of 670~780 nm, which is near-infrared emission, indicating that the compound can produce near-infrared phosphorescence.

[0038] The steady-state spectrum of Example 2 (DCPPBr) has a similar emission position to its phosphorescence spectrum, both showing orange-red light emission, indicating that the emission of this compound mainly comes from phosphorescence, and its phosphorescence quantum efficiency was measured to be 6%.

[0039] Transient fluorescence spectra such as Figure 4 As shown, where, Figure 4 (a) in the figure is the transient fluorescence spectrum of DCPP in crystalline state in Example 1; Figure 4 (b) shows the transient fluorescence spectrum of DCPPBr in the crystalline state of Example 2; the results show that both compounds have a lifetime on the order of microseconds, indicating that their luminescence process involves triplet excitons and has typical phosphorescence characteristics.

[0040] Further temperature-dependent spectroscopy was performed on the two compounds; the results are as follows: Figure 5 As shown, where, Figure 5(a) in the figure is the temperature-variable steady-state spectrum of DCPP in crystalline state in Example 1; Figure 5 (b) in the figure is the temperature-variable steady-state spectrum of DCPPBr in the crystalline state of Example 2; from Figure 5 As can be seen, the emission intensity of both compounds gradually weakens with increasing temperature, ruling out the possibility of delayed fluorescence and further proving that their emission originates from phosphorescence. Among them, Example 2 (DCPPBr) still showed a significant phosphorescence emission peak at a high temperature of 423 K, indicating that the compound has excellent thermal stability.

[0041] Furthermore, excitation spectra of the two compounds were measured, and the results are as follows: Figure 6 As shown, the excitation spectra of Examples 1 and 2 both cover the 315~520 nm wavelength range, indicating that the two compounds can be effectively excited in the range of ultraviolet to blue and green light.

[0042] Furthermore, the phosphorescence spectra of the two compounds at excitation wavelengths of 365 nm, 400 nm, 450 nm, and 490 nm were measured, and the results are as follows: Figure 7 As shown, where, Figure 7 (a) shows the phosphorescence spectra of the DCPP crystalline state in Example 1 under different excitations; Figure 7 (b) shows the phosphorescence spectrum of the DCPPBr crystal in Example 2 under different excitations. Obvious phosphorescence emission was observed under all four excitation wavelengths. This result indicates that the two compounds can produce phosphorescence not only under ultraviolet light excitation, but also under visible light (including blue and blue-green light) excitation, and have potential application value in fields such as bioimaging. Furthermore, the emission spectra of Examples 1 and 2 under X-ray excitation conditions were tested, and the results are as follows: Figure 8 As shown. Figure 8 (a) in the figure is the radiation emission spectrum of DCPP in crystalline state in Example 1 (X-ray source voltage is 40 kV). Figure 8 (b) shows the radiative emission spectrum of DCPPBr in crystalline state in Example 2 (X-ray source voltage is 40 kV). Figure 8 It can be seen that both compounds can produce obvious emission signals under X-ray excitation. Combined with the aforementioned test results of ultraviolet and visible light excitation, it can be confirmed that the phosphorescence of the compounds obtained in this invention can be emitted under three excitation conditions: ultraviolet light, visible light, and X-ray, exhibiting tri-mode excitation characteristics.

[0043] Furthermore, using epoxy resin as the main component, doped thin films were prepared using the compounds obtained in Examples 1 and 2 as the guest, with a doping ratio of 1%, and their application in X-ray imaging was tested. The doped thin film was used as the luminescent background, and the chip was placed between the X-ray source and the doped thin film, and images were taken with a camera. The results are as follows. Figure 9 As shown. Figure 9 (a) in the text is Example 1; Figure 9 (b) in the text is Example 2. From Figure 9 As can be seen, the internal circuit structure of the chip is displayed, presenting clear details. The pins and connections of the circuit are shown with sharp black outlines, arranged neatly in a radial pattern, while the central area is a darker square core, highlighting differences in material density or thickness. The overall image has clear layers, highlighting the resolution advantage of X-ray imaging in revealing the internal structure and potential defects of chips.

[0044] Furthermore, single crystals from Examples 1 and 2 were grown using a mixed solvent evaporation method, and their crystal structures were characterized using X-ray single-crystal diffraction. The results are as follows: Figure 10 As shown. Figure 10 (a) in the figure is an intermolecular interaction diagram of DCPP in Example 1; Figure 10 (b) in the diagram is the intermolecular interaction diagram of DCPPBr in Example 2. Figure 10 As can be seen, the compounds of this invention possess good molecular planarity and a large π-conjugated system, which is beneficial for achieving efficient light absorption and energy transfer under ultraviolet light excitation, thereby producing stable room-temperature phosphorescence. Simultaneously, the compounds readily form π-π stacking interactions, which significantly reduce the band gap, causing a redshift in the absorption and emission spectra of the material, thus enabling phosphorescence emission even under visible light excitation. Furthermore, the molecular skeleton of the compounds described in this invention shares certain structural similarities with traditional organic scintillator anthracene molecules, endowing them with energy transfer and excitation properties under high-energy X-ray excitation. Through the synergistic effect of the aforementioned molecular structural features and interaction mechanisms, this type of material can produce stable room-temperature phosphorescence emission under three different excitation conditions: ultraviolet light, visible light, and X-rays, exhibiting unique tri-mode excitation characteristics.

[0045] The present invention has been described in detail above with reference to the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. The application of a dibenzoquinoxaline compound in organic phosphorescent materials, characterized in that, The dibenzoquinoxaline compounds have the structural formula shown in formula (I): ； X1 and X2 are each independently selected from H or halogens.

2. The application according to claim 1, characterized in that, X1 and X2 are the same.

3. The application according to claim 1 or 2, characterized in that, X1 and X2 are selected from H, F, Cl, Br, and I.

4. The application according to claim 1, characterized in that, The dibenzoquinoxaline compounds are selected from the following structural formulas: 。 5. The application according to any one of claims 1 to 4, characterized in that, The dibenzoquinoxaline compounds were prepared by the following method: Compound 1 and compound 2 are subjected to a condensation reaction to obtain the product; The structural formulas of compound 1 and compound 2 are shown below: 。 6. The application according to claim 5, characterized in that, The reaction temperature of the condensation reaction is 110℃~120℃.

7. The application according to claim 5, characterized in that, The reaction time for the condensation reaction is 8 h to 12 h.

8. The application according to claim 5, characterized in that, The solvent for the condensation reaction includes at least one of acetic acid, formic acid, and p-toluenesulfonic acid-DMF system.

9. The application according to claim 1, characterized in that, The dibenzoquinoxaline compounds produce phosphorescence under ultraviolet light, visible light, and X-ray excitation.

10. The application according to claim 1, characterized in that, The application of dibenzoquinoxaline compounds as organic phosphorescent materials in bioimaging or X-ray imaging.

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