Near-infrared organic luminescent material with high fluorescence quantum yield, preparation method and application thereof

Abstract

The application discloses a kind of high fluorescent quantum yield near-infrared organic luminescent material and preparation method and application, the chemical name of the material is 4,8-di (5-pyrene-3-(2-butyl octyl) thien-2-yl) benzo [1,2-C:4,5-C] double ([1,2,5] thiazole). With new push-pull electronic structure, wherein benzo double thiazole is electron acceptor, pyrene is electron donor, 3-(2-butyl octyl) thienyl group expands the conjugated structure of molecule. The maximum absorption and emission wavelength of the material in tetrahydrofuran are 638 nm and 970 nm respectively, and the absolute fluorescent quantum yield is 2.6%, and the absolute fluorescent quantum yield of its powder state is 21.9%. The application can provide a powerful tool for improving near-infrared fluorescence imaging depth, signal-to-noise ratio and space-time resolution.

Description

Technical Field

[0001] This invention relates to the field of organic light-emitting materials, and particularly to a near-infrared organic light-emitting material with high fluorescence quantum yield, its preparation method, and its applications. Background Technology

[0002] Fluorescence imaging is an optical visualization technique that plays an irreplaceable role in the biomedical field. It boasts advantages such as high sensitivity, high spatiotemporal resolution, and ease of operation. However, most organic light-emitting materials currently used in this technique have short absorption or emission wavelengths, resulting in shallow imaging depth and severe light scattering, particularly in biological tissue imaging where significant background fluorescence signals are generated, thus limiting its application scenarios. In recent years, fluorescence imaging technology based on near-infrared organic light-emitting materials has attracted widespread attention due to its advantages such as deeper imaging depth, lower light scattering, and weaker background fluorescence signals. With the continuous improvement of imaging depth, signal-to-noise ratio, and spatiotemporal resolution, the requirements for the fluorescence quantum yield of near-infrared organic light-emitting materials are also increasing. However, the reported fluorescence quantum yields of near-infrared organic light-emitting materials are generally low; therefore, developing near-infrared organic light-emitting materials with high fluorescence quantum yields is particularly important. Summary of the Invention

[0003] The present invention aims to provide a near-infrared organic light-emitting material with high fluorescence quantum yield, its preparation method, and its applications. This material possesses a novel push-pull electron structure, in which benzobisthiadiazole acts as the electron acceptor, pyrene as the electron donor, and a 3-(2-butyloctyl)thiophene group expands the conjugated structure of the molecule. The material exhibits maximum absorption and emission wavelengths of 638 nm and 970 nm in tetrahydrofuran, respectively, with an absolute fluorescence quantum yield of 2.6%, and an absolute fluorescence quantum yield of 21.9% in its powder state. This invention provides a powerful tool for improving the depth, signal-to-noise ratio, and spatiotemporal resolution of near-infrared fluorescence imaging.

[0004] The present invention discloses a near-infrared organic light-emitting material with high fluorescence quantum yield, the structural formula (I) of which is as follows:

[0005] (I) Among them, the chemical name of structural formula (Ⅰ) is 4,8-bis(5-pyrene-3-(2-butyloctyl)thiophene-2-yl)benzo[1,2-C:4,5-C]bis([1,2,5]thiadiazole).

[0006] The preparation method of the near-infrared organic light-emitting material with high fluorescence quantum yield is carried out according to the following steps: Preparation of organic light-emitting materials: a. Under a protective atmosphere, compound I (4,8-bis(5-bromo-3-(2-butyloctyl)thiophen-2-yl)benzo[1,2-C:4,5-C]bis([1,2,5]thiadiazole), compound II (4,4,5,5-tetramethyl-1,3,2-dioxoboronylpentane-2-ylpyrene), bis(triphenylphosphine)palladium dichloride, and potassium carbonate are added to the solvent tetrahydrofuran at a mass ratio of 1:4-8. The mixture is heated and stirred at 70-75℃ for 24-48 h to obtain a reaction solution, wherein the mass ratio of compound I to bis(triphenylphosphine)palladium dichloride is 1:0.01-0.1. b. After cooling the reaction solution obtained in step a, extract it with ethyl acetate and water, then dry the organic phase with anhydrous sodium sulfate, and concentrate it to obtain the crude product; c. The crude product obtained in step b is purified by column chromatography with silica packing material. The eluent is dichloromethane and petroleum ether in a volume ratio of 1:3 to obtain a near-infrared organic light-emitting material with high fluorescence quantum yield. Preparation of nanoparticles: d. Dissolve the near-infrared organic light-emitting material with high fluorescence quantum yield obtained in step c and the coating carrier material disteaylphosphatidylethanolamine-polyethylene glycol 2000 in tetrahydrofuran and stir until homogeneous to obtain a mixed solution; under ultrasonic conditions, add the mixed solution dropwise to water, dialyze, and concentrate by ultrafiltration to obtain nanoparticles.

[0007] This invention discloses a near-infrared organic light-emitting material with high fluorescence quantum yield, its preparation method, and its applications. The synthetic route of this material is as follows:

[0008] The present invention relates to a high fluorescence quantum yield near-infrared organic light-emitting material, its preparation method, and its application. The technical solution adopted to solve this technical problem is: introducing benzobisthiadiazole as an electron acceptor, pyrene as an electron donor, and a 3-(2-butyloctyl)thiophene group to expand the conjugated structure of the molecule.

[0009] With the continuous improvement of fluorescence imaging depth, signal-to-noise ratio, and spatiotemporal resolution, the requirements for the fluorescence quantum yield of near-infrared organic light-emitting materials (NIR organic light-emitting materials) are also increasing. However, the reported fluorescence quantum yields of NIR organic light-emitting materials are generally low, making the development of NIR organic light-emitting materials with high fluorescence quantum yields particularly important. The high fluorescence quantum yield NIR organic light-emitting material described in this invention demonstrates great application potential in near-infrared fluorescence imaging technology due to its high quantum yield.

[0010] Beneficial Effects: Compared with existing technologies, the near-infrared organic light-emitting material with high fluorescence quantum yield provided by this invention possesses a novel push-pull electronic structure, wherein benzobisthiadiazole acts as an electron acceptor, pyrene as an electron donor, and a 3-(2-butyloctyl)thiophene group extends the conjugated structure of the molecule. Compared with the commercial standard sample IR26 (with an absolute quantum yield of 0.05% in 1,2-dichloroethane), this material achieves an absolute fluorescence quantum yield of 2.6% in tetrahydrofuran, and its absolute fluorescence quantum yield in powder form reaches 21.9%. Attached Figure Description

[0011] Figure 1 The image shows the 1H NMR spectrum of the Py3TBBT material of this invention in deuterated dichloromethane. Figure 2 The image shows the carbon NMR spectrum of the Py3TBBT material of this invention in deuterated dichloromethane. Figure 3 The absorption and emission spectra of the Py3TBBT material of the present invention in tetrahydrofuran are shown. Figure 4 This is a graph showing the absolute fluorescence quantum efficiency of the Py3TBBT material in tetrahydrofuran of the present invention; Figure 5 This is a graph showing the absolute fluorescence quantum efficiency of the Py3TBBT material in powder form according to the present invention; Figure 6 The absorption and emission spectra of the Py3TBBT nanoparticles of the present invention in water are shown. Figure 7 This is a near-infrared fluorescence imaging of mouse blood vessels by Py3TBBT nanoparticles of the present invention, showing the statistical results of the full width at half maximum (FWHM) and signal-to-background ratio. Detailed Implementation

[0012] The present invention will be further described below with reference to the accompanying drawings, but is not limited to the embodiments described below. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the present invention. Example 1

[0013] Preparation of organic light-emitting materials: a. Under a protective atmosphere, compound I 4,8-bis(5-bromo-3-(2-butyloctyl)thiophen-2-yl)benzo[1,2-C:4,5-C]bis([1,2,5]thiadiazole) 853 mg, 1 mmol; compound II 4,4,5,5-tetramethyl-1,3,2-dioxoboronyl-2-ylpyrene 1313 mg, 4 mmol; bis(triphenylphosphine)palladium dichloride 7 mg, 0.01 mmol; and potassium carbonate 276 mg, 2 mmol were added to 25 mL of tetrahydrofuran. The mixture was heated and stirred at 70 °C for 24 h to obtain a reaction solution, wherein the mass ratio of compound I to bis(triphenylphosphine)palladium dichloride was 1:0.01. b. After cooling the reaction solution obtained in step a, extract it with ethyl acetate and water, then dry the organic phase with anhydrous sodium sulfate, and concentrate it to obtain the crude product; c. The crude product obtained in step b was purified by column chromatography with silica packing. The eluent was dichloromethane and petroleum ether in a volume ratio of 1:3. 560 mg of near-infrared organic light-emitting material with high fluorescence quantum yield was obtained, with a yield of 51%. Preparation of nanoparticles: d. Dissolve 1 mg of the high fluorescence quantum yield near-infrared organic light-emitting material obtained in step c and 5 mg of distearate phosphatidylethanolamine-polyethylene glycol 2000 in 1 mL of tetrahydrofuran and stir until homogeneous to obtain a mixed solution. Under ultrasonic conditions, add the mixed solution dropwise to 9 mL of ultrapure water and sonicate with an ultrasonic probe for 2 minutes at an output power of 45%. Then pour the mixture into a dialysis bag with a molecular weight cutoff of 3500 Da, add 5 L of ultrapure water and dialyze for 24 h. After ultrafiltration and concentration, nanoparticles are obtained. Example 2

[0014] Preparation of organic light-emitting materials: a. Under a protective atmosphere, compound I 4,8-bis(5-bromo-3-(2-butyloctyl)thiophen-2-yl)benzo[1,2-C:4,5-C]bis([1,2,5]thiadiazole) 853 mg, 1 mmol; compound II 4,4,5,5-tetramethyl-1,3,2-dioxoboronylpentane-2-ylpyrene 1969 mg, 6 mmol; bis(triphenylphosphine)palladium dichloride 35 mg, 0.05 mmol; and potassium carbonate 276 mg, 2 mmol were added to 25 mL of tetrahydrofuran. The mixture was heated and stirred at 75 °C for 48 h to obtain a reaction solution, wherein the mass ratio of compound I to bis(triphenylphosphine)palladium dichloride was 1:0.05. b. After cooling the reaction solution obtained in step a, extract it with ethyl acetate and water, then dry the organic phase with anhydrous sodium sulfate, and concentrate it to obtain the crude product; c. The crude product obtained in step b is purified by column chromatography with silica packing material. The eluent is dichloromethane and petroleum ether in a volume ratio of 1:3 to obtain a near-infrared organic light-emitting material with high fluorescence quantum yield. d. Dissolve 1 mg of the high fluorescence quantum yield near-infrared organic light-emitting material obtained in step c and 5 mg of distearate phosphatidylethanolamine-polyethylene glycol 2000 in 1 mL of tetrahydrofuran and stir until homogeneous to obtain a mixed solution. Under ultrasonic conditions, add the mixed solution dropwise to 9 mL of ultrapure water and sonicate with an ultrasonic probe for 2 minutes at an output power of 45%. Then pour the mixture into a dialysis bag with a molecular weight cutoff of 3500 Da, add 5 L of ultrapure water and dialyze for 24 h. After ultrafiltration and concentration, nanoparticles are obtained. Example 3

[0015] Preparation of organic light-emitting materials: a. Under a protective atmosphere, compound I 4,8-bis(5-bromo-3-(2-butyloctyl)thiophen-2-yl)benzo[1,2-C:4,5-C]bis([1,2,5]thiadiazole) 853 mg, 1 mmol; compound II 4,4,5,5-tetramethyl-1,3,2-dioxoboronylpentane-2-ylpyrene 2626 mg, 8 mmol; bis(triphenylphosphine)palladium dichloride 70 mg, 0.1 mmol; and potassium carbonate 276 mg, 2 mmol were added to 25 mL of tetrahydrofuran. The mixture was heated and stirred at 73 °C for 36 h to obtain a reaction solution, wherein the mass ratio of compound I to bis(triphenylphosphine)palladium dichloride was 1:0.1. b. After cooling the reaction solution obtained in step a, extract it with ethyl acetate and water, then dry the organic phase with anhydrous sodium sulfate, and concentrate it to obtain the crude product; c. The crude product obtained in step b is purified by column chromatography with silica packing material. The eluent is dichloromethane and petroleum ether in a volume ratio of 1:3 to obtain a near-infrared organic light-emitting material with high fluorescence quantum yield.

[0016] Preparation of nanoparticles: 1 mg of the high fluorescence quantum yield near-infrared organic light-emitting material obtained in step c was dissolved in 1 mL of tetrahydrofuran and stirred until homogeneous to obtain a mixed solution. The mixed solution was then added dropwise to 9 mL of ultrapure water under ultrasonic conditions and sonicated for 2 minutes with an ultrasonic probe at 45% output power. Subsequently, the mixture was poured into a dialysis bag with a molecular weight cutoff of 3500 Da, added to 5 L of ultrapure water, and dialyzed for 24 h. After ultrafiltration and concentration, nanoparticles were obtained. Example 4

[0017] An application of Py3TBBT nanoparticles for near-infrared fluorescence imaging of mouse blood vessels is provided, and the specific operation steps are as follows: 200 μL of any one of the Py3TBBT nanoparticles from Examples 1-3 was injected into the tail vein of mice. After anesthetizing the mice, near-infrared fluorescence imaging of the blood vessels was performed using an in vivo imaging system. The excitation wavelength was set to 660 nm and the current to 8000 mA. Near-infrared fluorescence images of the mouse blood vessels were acquired under filters at 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1400 nm, and 1500 nm. Quantitative analysis (fluorescence intensity, Gaussian fit, signal-to-background ratio (SBR), and full width at half maximum (FWHM)) was then performed on the images acquired under each filter. The results are as follows: Figure 7 As shown, quantitative analysis was performed on the white line-marked area of ​​the blood vessels in the hind limbs of mice.

[0018] The high fluorescence quantum yield near-infrared organic light-emitting material of this invention possesses a novel push-pull electron structure, in which benzobisthiadiazole acts as the electron acceptor, pyrene as the electron donor, and a 3-(2-butyloctyl)thiophene group extends the conjugated structure of the molecule. This unique molecular structure enables it to achieve an absolute fluorescence quantum yield of 2.6% in tetrahydrofuran and 21.9% in its powder state; compared to the commercial standard sample IR26 (with an absolute quantum yield of 0.05% in 1,2-dichloroethane), this material exhibits a significant advantage in fluorescence quantum yield.

Claims

1. A near-infrared organic light-emitting material with high fluorescence quantum yield, characterized in that, The structural formula (Ⅰ) of the material is as follows: （Ⅰ） Among them, the chemical name of structural formula (Ⅰ) is 4,8-bis(5-pyrene-3-(2-butyloctyl)thiophene-2-yl)benzo[1,2-C:4,5-C]bis([1,2,5]thiadiazole).

2. A method for preparing a near-infrared organic light-emitting material with high fluorescence quantum yield as described in claim 1, characterized in that, Follow these steps: Preparation of organic light-emitting materials: a. Under a protective atmosphere, compound I (4,8-bis(5-bromo-3-(2-butyloctyl)thiophen-2-yl)benzo[1,2-C:4,5-C]bis([1,2,5]thiadiazole), compound II (4,4,5,5-tetramethyl-1,3,2-dioxoborane-2-ylpyrene), bis(triphenylphosphine)palladium dichloride, and potassium carbonate) are added to tetrahydrofuran solvent at a mass ratio of 1:4-8. The mixture is heated and stirred at 70-75 °C for 24-48 h to obtain a reaction solution. The mass ratio of compound I to bis(triphenylphosphine)palladium dichloride is 1:0.01-0.

1. b. After cooling the reaction solution obtained in step a, extract it with ethyl acetate and water, then dry the organic phase with anhydrous sodium sulfate, and concentrate it to obtain the crude product; c. The crude product obtained in step b is purified by column chromatography with silica packing material. The eluent is dichloromethane and petroleum ether in a volume ratio of 1:3 to obtain a near-infrared organic light-emitting material with high fluorescence quantum yield. Preparation of nanoparticles: d. Dissolve the near-infrared organic light-emitting material with high fluorescence quantum yield obtained in step c and the coating carrier material disteaylphosphatidylethanolamine-polyethylene glycol 2000 in tetrahydrofuran and stir until homogeneous to obtain a mixed solution; under ultrasonic conditions, add the mixed solution dropwise to water, dialyze, and concentrate by ultrafiltration to obtain nanoparticles.

3. The application of a near-infrared organic light-emitting material with high fluorescence quantum yield as described in claim 1 in the preparation of near-infrared fluorescence imaging reagents.

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