D-A type near-infrared second-region high-brightness organic fluorescent material and preparation method thereof

Abstract

The invention provides a D-A type near-infrared second-region high-brightness organic fluorescent material and a preparation method thereof, and relates to the field of materials. Raw materials of the organic fluorescent material comprise an acceptor unit and a donor unit; the acceptor unit comprises any one or more of a benzobis (thiadiazole) derivative and a thiadiazole quinoxaline derivative; the donor unit comprises a compound with electron donating capability. The preparation method of the D-A type near-infrared second-region high-brightness organic fluorescent material comprises the following steps: mixing the acceptor unit, the donor unit, a catalyst and an organic solvent in a protective atmosphere, and carrying out nucleophilic substitution reaction to obtain the D-A type near-infrared second-region high-brightness organic fluorescent material. According to the D-A type near-infrared second-region high-brightness organic fluorescent material provided by the invention, the emission wavelength of the material is expanded to a near-infrared second region, and meanwhile, the fluorescence quantum yield is enhanced; the organic fluorescent material has the characteristics of simple molecular structure, high yield and the like.

Description

Technical Field

[0001] This invention belongs to the field of materials technology, and particularly relates to a DA-type near-infrared II high-brightness organic fluorescent material and its preparation method. Background Technology

[0002] High-quality optical imaging is crucial for the diagnosis and treatment of deep tissue diseases. In recent years, near-infrared II (NIR-II, 1000-1700 nm) fluorescence imaging has attracted widespread attention in biomedical applications due to its higher spatial resolution and better signal-to-noise ratio. Developing NIR-II fluorescent probes with long absorption / emission wavelengths, high brightness, and good biocompatibility has been an important research direction in the field of optical imaging. Compared to the drawbacks of inorganic fluorescent probes, such as poor biocompatibility and high heavy metal toxicity, organic small molecule fluorescent materials have well-defined structures and lower biotoxicity. Among them, DA-type molecules have gained widespread academic attention due to their typically extended π-electron system, low HOMO-LUMO band gap, and inherent intramolecular charge transfer (ICT) effect. Small molecule fluorescent dyes constructed using DA structures often facilitate the movement of fluorescent bands towards the NIR-II biological window.

[0003] In view of this, the present invention is hereby proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a DA-type near-infrared II high-brightness organic fluorescent material and its preparation method, so as to solve the above-mentioned problems.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A DA-type near-infrared II high-brightness organic fluorescent material, the raw materials of which include acceptor units and donor units;

[0007] The receptor unit includes one or more of benzobisthiadiazole derivatives and thiadiazole quinoxaline derivatives;

[0008] The donor unit includes a compound with electron-donating capability.

[0009] Preferably, the receptor unit comprises one or more compounds represented by the following general structural formulas:

[0010]

[0011] Where X is sulfur and / or selenium, Y is one or more of the halogens, and Z is... One or more of them.

[0012] Among the selected acceptor units, benzobisthiadiazole derivatives have high electron affinity and quinone-like properties, while thiadiazole quinoxaline derivatives have strong electron-withdrawing ability, stability, and high solubility.

[0013] Preferably, the donor unit includes One or more of the following;

[0014] Wherein, R is one or more of hydrogen, methyl, and methoxy, and T is any one of amino, mercapto, and selenool.

[0015] Preferably, the DA-type near-infrared II high-brightness organic fluorescent material comprises one or more compounds represented by the following general formulas:

[0016]

[0017] Where X is sulfur or selenium; Y is one or more of Br, Cl, and F; Z is... Any one of the following; R is one or more of hydrogen, methyl, and methoxy; T is any one of amino, mercapto, and selenool.

[0018] Preferably, the DA-type near-infrared II high-brightness organic fluorescent material comprises one or more compounds shown in the following structural formulas:

[0019]

[0020]

[0021]

[0022]

[0023] This application also provides a method for preparing the aforementioned DA-type near-infrared II high-brightness organic fluorescent material, comprising:

[0024] Under a protective atmosphere, the acceptor unit, the donor unit, the catalyst, and the organic solvent are mixed and subjected to a nucleophilic substitution reaction to obtain the DA-type near-infrared II high-brightness organic fluorescent material.

[0025] Preferably, the mixture includes:

[0026] Mix one of the acceptor unit or the donor unit, the catalyst, and the organic solvent for 30-60 minutes, stir, and then add the other corresponding donor unit or acceptor unit.

[0027] Adding one unit first, followed by another, can accelerate the occurrence of affinity substitution reactions.

[0028] Preferably, the preparation method of the DA-type near-infrared II high-brightness organic fluorescent material satisfies one or more of the following conditions:

[0029] (1) The nucleophilic substitution reaction was carried out at room temperature for 2-12 hours.

[0030] (2) The molar ratio of the acceptor unit to the donor unit is 1:0.5-2.5;

[0031] (3) The catalyst includes one or more of cesium carbonate, sodium hydride, and tris(dibenzylacetone)palladium;

[0032] (4) The organic solvent includes one or more of tetrahydrofuran and toluene.

[0033] Preferably, when X in the acceptor unit is S and the corresponding position in the DA-type near-infrared II high-brightness organic fluorescent material is Se, the nucleophilic substitution reaction further includes:

[0034] The product of the nucleophilic substitution reaction was mixed with glacial acetic acid and subjected to a first reaction catalyzed by zinc powder. After the product was cooled, water was added and the mixture was filtered to obtain a solid. The solid was then reacted with selenium dioxide in a dichloromethane system to obtain the DA-type near-infrared II high-brightness organic fluorescent material.

[0035] Preferably, the temperature of the first reaction is 60-80℃ and the time is 4-6 hours;

[0036] The second reaction was carried out at room temperature for 8-12 hours.

[0037] The beneficial effects of this invention are:

[0038] The DA-type near-infrared II high-brightness organic fluorescent material provided in this application selects benzobisthiadiazole derivatives and thiadiazoquinoxaline derivatives with high electron affinity as acceptor units to enhance the intramolecular charge transfer (ICT) effect of the DA structure. By introducing donor units with differences in structure and electron-donating ability, the emission wavelength of the material can be effectively extended to the near-infrared II region, while simultaneously enhancing the fluorescence quantum yield. The high-brightness near-infrared II organic fluorescent material features a simple molecular structure and high yield. Furthermore, modification sites can be retained at one end of the molecule, facilitating the introduction of water-soluble groups or targeting groups for the construction of high-brightness near-infrared II fluorescent probes and tumor-specific imaging, laying a material foundation for subsequent biological applications.

[0039] To date, benzobisthiadiazole derivatives and thiadiazoquinoxaline derivatives have been widely used as strong electron acceptors to construct DA-type fluorophores with strong NIR absorption and NIR-II fluorescence emission. To develop superior NIR-II fluorescent molecules based on these two types of acceptor units, the following two basic conditions must be considered: (i) fluorescence emission capability in the NIR-II region; and (ii) high fluorescence quantum yield and high fluorescence brightness.

[0040] In summary, for DA-type near-infrared II high-brightness organic fluorescent materials, achieving tunable molecular absorption / emission wavelengths while maintaining high brightness, under the premise of simplifying the synthesis process, is a key technical challenge that needs to be overcome in this field.

[0041] The method for preparing DA-type near-infrared II high-brightness organic fluorescent materials provided in this application synthesizes small organic fluorescent molecules with tunable NIR absorption and NIR-II emission, high fluorescence quantum yield, and stable chemical structure through nucleophilic substitution reaction. The synthesis method is simple, has high yield, and can be used for industrial application. Attached Figure Description

[0042] 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, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 The product obtained in Example 2 1 H NMR spectrum;

[0044] Figure 2 The ultraviolet absorption spectrum of the product obtained in Example 2 in tetrahydrofuran solution;

[0045] Figure 3 The emission spectrum of the product obtained in Example 2 in tetrahydrofuran solution;

[0046] Figure 4 This is a graph showing the absolute fluorescence quantum yield of the product obtained in Example 2 in tetrahydrofuran solution. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] Example 1

[0049] This embodiment provides a DA-type near-infrared II region high-brightness organic fluorescent material, the preparation method of which is as follows:

[0050] Under N2 protection, cesium carbonate (Cs2CO3, 92 mg, 0.298 mmol, 1 eq) was placed in a round-bottom flask, and an anhydrous tetrahydrofuran solution of 2,6-dimethylbenzylthiophenol (0.298 mmol, 1 eq) was added. The reaction was carried out at room temperature for 30 min. 4,8-Dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (100 mg, 0.284 mmol, 1 eq) was dissolved in anhydrous tetrahydrofuran and added to the above reaction system. The mixture was stirred at room temperature for 2 h. Yield: 70%. 1 H NMR (600MHz, Chloroform-d) δ7.20 (t, J = 7.5 Hz, 2H), 7.11 (d, J = 7.4 Hz, 4H), 2.40 (s, 12H).

[0051] The reaction equation is as follows:

[0052]

[0053] Example 2

[0054] This embodiment provides a DA-type near-infrared II region high-brightness organic fluorescent material, the preparation method of which is as follows:

[0055] Under N2 protection, Cs2CO3 (92 mg, 0.596 mmol, 2 eq) was placed in a round-bottom flask, and an anhydrous tetrahydrofuran solution of 2,6-dimethylbenzylthiophenol (0.596 mmol, 2 eq) was added. The reaction was carried out at room temperature for 30 min. 4,8-Dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (100 mg, 0.284 mmol, 1 eq) was dissolved in anhydrous tetrahydrofuran and added to the above reaction system. The mixture was stirred at room temperature for 2 h. Yield: 83%. 1H NMR (600MHz, Chloroform-d) δ7.18 (t, J = 7.5 Hz, 2H), 7.09 (d, J = 7.4 Hz, 4H), 2.40 (s, 12H).

[0056] The structural characterization data of this substance are as follows: Figure 1 As shown. The reaction equation is as follows:

[0057]

[0058] Figure 2 The absorption spectrum of the product prepared in this example in tetrahydrofuran solvent is given by... Figure 2 It can be seen that the ultraviolet absorption of the product obtained in this embodiment is red-shifted to 642nm, and it has obvious absorbance in the near-infrared region.

[0059] Figure 3 The emission spectrum of the product prepared in this example in tetrahydrofuran solvent is given by... Figure 3 It can be seen that the maximum emission wavelength of the product obtained in this embodiment is redshifted to 802nm, and it has obvious tail emission in the near-infrared II region.

[0060] Figure 4 The absolute fluorescence quantum yield (integration range 700-1200 nm) of the product prepared in this example, measured in tetrahydrofuran solvent, is given by... Figure 4 It can be seen that the absolute fluorescence quantum yield of the product obtained in this embodiment is as high as 15.26%.

[0061] Example 3

[0062] This embodiment provides a DA-type near-infrared II region high-brightness organic fluorescent material, the preparation method of which is as follows:

[0063] Under N2 protection, the intermediate 4,7-bis((2,6-dimethylphenyl)thio)-5,6-dinitrobenzo[c][1,2,5]thiadiazole (200 mg, 0.4 mmol, 1 eq) was dispersed with zinc powder (524 mg, 8 mmol, 20 eq) in 25 mL of glacial acetic acid solution and reacted at 60 °C for 4 h. After the reaction solution cooled to room temperature, 50 mL of water was added to precipitate the precipitate. The resulting precipitate was further reacted with SeO2 (440 mg, 4.0 mmol, 10 eq) in distilled dichloromethane solution for 8 h. Yield: 21%. 1 H NMR (600MHz, Chloroform-d) δ7.17 (t, J = 7.6 Hz, 2H), 7.08 (d, J = 7.6 Hz, 4H), 2.40 (s, 12H).

[0064] Example 4

[0065] This embodiment provides a DA-type near-infrared II region high-brightness organic fluorescent material, the preparation method of which is as follows:

[0066] Under N2 protection, sodium hydride (NaH, 14.30 mg, 0.596 mmol, 2 eq) was placed in a round-bottom flask, and an anhydrous tetrahydrofuran solution of 2,6-dimethylbenzeneselenophenol (0.596 mmol, 2 eq) was added. The reaction was carried out at room temperature for 30 min. 4,8-Dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (100 mg, 0.284 mmol, 1 eq) was dissolved in anhydrous tetrahydrofuran and added to the above reaction system. The mixture was stirred at room temperature for 2 h. Yield: 64%. 1 H NMR (600MHz, Chloroform-d) δ7.17 (t, J=7.5Hz, 2H), 7.10 (d, J=7.4Hz, 4H), 2.41 (s, 12H).

[0067] The reaction equation is as follows:

[0068]

[0069] Example 5

[0070] This embodiment provides a DA-type near-infrared II region high-brightness organic fluorescent material, the preparation method of which is as follows:

[0071] Under N2 protection, 4,7-dibromo-5,6-diaminophenyl[c][1,2,5]thiadiazole (194 mg, 0.6 mmol, 1 eq) and bibenzoyl (126 mg, 0.6 mmol, 1 eq) were dispersed in 20 mL of glacial acetic acid solution and reacted at 100 °C for 72 h. The reaction mixture was purified to yield the intermediate 4,9-dibromo-6,7-diphenyl-[1,2,5]thiadiazole[3,4-g]quinoxaline.

[0072] Under N2 protection, Cs2CO3 (92 mg, 0.596 mmol, 2 eq) was placed in a round-bottom flask, and an anhydrous tetrahydrofuran solution of 2,6-dimethylbenzylthiophenol (0.596 mmol, 2 eq) was added. The reaction was carried out at room temperature for 30 min. The intermediate 4,9-dibromo-6,7-diphenyl-[1,2,5]thiadiazole[3,4-g]quinoxaline (141 mg, 0.284 mmol, 1 eq) was dissolved in anhydrous tetrahydrofuran and added to the above reaction system. The mixture was stirred at room temperature for 12 h. Yield: 52%. 1H NMR (500MHz, Chloroform-d) δ7.85-7.79(m,2H),7.41-7.34(m,1H),7.36-7.29(m,2H),7.25-7.20(m,2H),7.10(dd,J=7.9,7.1Hz,1H),2.27(s,5H).

[0073] The reaction equation is as follows:

[0074]

[0075] Example 6

[0076] This embodiment provides a DA-type near-infrared II region high-brightness organic fluorescent material, the preparation method of which is as follows:

[0077] Under N2 protection, indoline (143 mg, 1.2 mmol, 3 eq), ligand 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (X-phos, 19.04 mg, 0.08 mmol), Cs2CO3 (390.96 mg, 1.2 mmol), and tris(dibenzylideneacetone)dipalladium (18.30 mg, 0.04 mmol) were reacted in a round-bottom flask for 30 min. Then, the intermediate 4,9-dibromo-6,7-diphenyl-[1,2,5]thiadiazole[3,4-g]quinoxaline (200 mg, 0.4 mmol, 1 eq) was dissolved in toluene and added to the above system. The mixture was refluxed in toluene solution at 120 °C for 12 h, with a yield of 62%. 1 H NMR(500MHz,Chloroform-d)δ7.69-7.63(m,2H),7.42-.36(m,1H),7.36--7.29(m,2H),7.15(td,J=7.4,1.6Hz,1H),7.09(td,J= 7.5,1.7Hz,1H),7.07-6.98(m,2H),4.21(t,J=.1Hz,2H),3.22(dtd,J=12.3,7.0,0.9Hz,1H),3.09(dtd,J=12.4,7.2,1.1Hz,1H).

[0078] The reaction equation is as follows:

[0079]

[0080] Comparative Example 1

[0081] Tang et al. rationally designed the zwitterionic molecule ITB by combining high DA strength with extended gel coupling to form a propeller-like molecular structure (Tang BZ et al. Adv. Funct. Mater. 2021, 31, 2007026). ITB exhibited excellent performance in near-infrared fluorescence imaging, showing a maximum emission at 759 nm and an absolute fluorescence quantum yield of 2.40% in ethanol solution. Tanaka et al. reported the DA-type boron fluoride-containing fused azobenzene complex CF3-BT (Tanaka et al. Angew. Chem. Int. Ed. 2024, 63, e202404178). The fluorination of the azobenzene ligand and the trifluoromethylation of boron effectively lowered the LUMO energy level, and CF3-BT exhibited excellent absorption / fluorescence performance over a wide near-infrared range, with a maximum emission at 802 nm and an absolute fluorescence quantum yield of 11.70% in toluene solution. In comparison, the synthesis route of the DA-type near-infrared II high-brightness organic material proposed in this invention is simpler and has a higher absolute fluorescence quantum yield.

[0082] Comparative Example 2

[0083] The patent document "A Dual-Emission Thermally Activated Delayed Fluorescence Material, Its Preparation Method and Application" designs a series of benzothiadiazole derivative fluorescent materials with dual-emission thermally activated delayed fluorescence properties and emission wavelengths in the visible region, showing promising prospects for large-scale application in multi-dimensional anti-counterfeiting. In contrast, this invention employs benzobisthiadiazole derivatives and thiadiazole-quinoxaline derivatives with stronger acceptor capabilities to further enhance the ICT effect of the molecules. By regulating the donor structure and electron-donating ability, it focuses on the preparation method of DA-type high-brightness near-infrared II fluorescent materials. The high absolute fluorescence quantum yield and modifiable functional sites of the obtained dye lay the foundation for its application in near-infrared II tumor-specific imaging.

[0084] Please note that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A DA-type near-infrared II high-brightness organic fluorescent material, characterized in that, Its raw materials include acceptor units and donor units; The receptor unit includes one or more of benzobisthiadiazole derivatives and thiadiazole quinoxaline derivatives; The donor unit includes a compound with electron-donating capability.

2. The DA-type near-infrared II high-brightness organic fluorescent material according to claim 1, characterized in that, The receptor unit comprises one or more compounds represented by the following general structural formulas: Where X is sulfur and / or selenium, Y is one or more of the halogens, and Z is... One or more of them.

3. The DA-type near-infrared II high-brightness organic fluorescent material according to claim 1, characterized in that, The donor unit includes One or more of the following; Wherein, R is one or more of hydrogen, methyl, and methoxy, and T is any one of amino, mercapto, and selenool.

4. The DA-type near-infrared II high-brightness organic fluorescent material according to any one of claims 1-3, characterized in that, The DA-type near-infrared II high-brightness organic fluorescent material includes one or more compounds represented by the following general structural formulas: Where X is sulfur or selenium; Y is one or more of Br, Cl, and F; Z is... Any one of the following; R is one or more of hydrogen, methyl, and methoxy; T is any one of amino, mercapto, and selenool.

5. The DA-type near-infrared II high-brightness organic fluorescent material according to claim 4, characterized in that, The DA-type near-infrared II high-brightness organic fluorescent material includes one or more compounds shown in the following structural formulas:

6. A method for preparing a DA-type near-infrared II high-brightness organic fluorescent material according to any one of claims 1-5, characterized in that, include: Under a protective atmosphere, the acceptor unit, the donor unit, the catalyst, and the organic solvent are mixed and subjected to a nucleophilic substitution reaction to obtain the DA-type near-infrared II high-brightness organic fluorescent material.

7. The method for preparing DA-type near-infrared II high-brightness organic fluorescent material according to claim 6, characterized in that, The mixture includes: Mix one of the acceptor unit or the donor unit, the catalyst, and the organic solvent for 30-60 minutes, stir, and then add the other corresponding donor unit or acceptor unit.

8. The method for preparing DA-type near-infrared II high-brightness organic fluorescent material according to claim 6, characterized in that, One or more of the following conditions must be met: (1) The nucleophilic substitution reaction was carried out at room temperature for 2-12 hours. (2) The molar ratio of the acceptor unit to the donor unit is 1:0.5-2.5; (3) The catalyst includes one or more of cesium carbonate, sodium hydride, and tris(dibenzylacetone)palladium; (4) The organic solvent includes one or more of tetrahydrofuran and toluene.

9. The method for preparing the DA-type near-infrared II high-brightness organic fluorescent material according to any one of claims 6-8, characterized in that, When X is S in the acceptor unit and the corresponding position in the DA-type near-infrared II high-brightness organic fluorescent material is Se, the nucleophilic substitution reaction further includes: The product of the nucleophilic substitution reaction was mixed with glacial acetic acid and subjected to a first reaction catalyzed by zinc powder. After the product was cooled, water was added and the mixture was filtered to obtain a solid. The solid was then reacted with selenium dioxide in a dichloromethane system to obtain the DA-type near-infrared II high-brightness organic fluorescent material.

10. The method for preparing the DA-type near-infrared II high-brightness organic fluorescent material according to claim 9, characterized in that, The temperature of the first reaction is 60-80℃, and the time is 4-6 hours; The second reaction was carried out at room temperature for 8-12 hours.

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