A method for large-scale preparation of carbon dots with different fluorescence emission through solvent engineering

Abstract

This invention discloses a method for large-scale preparation of fluorescent carbon dots (CDs) with different fluorescence emission using solvent engineering. The method includes the following steps: using aromatic anhydride derivatives and aromatic amine derivatives as raw materials, and controlling the raw material ratio and reaction time via a one-step microwave-assisted method, four CDs emitting fluorescence ranging from blue to red were prepared, with fluorescence quantum yields of 28.6%, 26.8%, 20.9%, and 7.8%, respectively. By amplifying the reactants, CDs can be prepared on a large scale under ambient pressure, enabling the mass production of fluorescent CDs with different wavelengths. The fluorescent CDs with different wavelengths prepared by this invention possess abundant surface functional groups, high fluorescence quantum yields, uniform particle size distribution, and biocompatibility. They can be synthesized in large quantities in a short time and can be widely applied in fields such as analytical detection, information encryption, cell imaging, and disease diagnosis and treatment.

Description

Technical Field

[0001] This invention belongs to the field of zero-dimensional carbon quantum dot nanomaterials technology, specifically relating to a method for large-scale preparation of carbon dots with different fluorescence emission using solvent engineering. Background Technology

[0002] Carbon dots (CDs) are carbon nanomaterials with sizes in the nanometer range, typically less than 10 nm. They exhibit fluorescence properties and have good chemical stability, making them promising for applications in many fields such as optoelectronic devices, bioimaging, analytical detection, and disease diagnosis and treatment.

[0003] Traditional fluorescent nanomaterials, such as organic fluorescent molecules and semiconductor quantum dots, suffer from problems such as the presence of toxic substances like heavy metals, high production costs due to prolonged reactions under high temperature and pressure, and low production efficiency, which limit their large-scale production and application. Correlates of light (CDs), as an ideal alternative, have seen their large-scale synthesis become a research hotspot. With the deepening research into the luminescence mechanism of CDs, such as the discovery of aggregation-induced emission, theoretical guidance has been provided for the large-scale synthesis of CDs with specific luminescent properties. This facilitates the controllable preparation of different luminescent CDs by controlling reaction conditions. It provides technical support and innovative ideas for the large-scale synthesis of different luminescent CDs, accelerating the research and development process, reducing costs, and precisely controlling the luminescence mechanism.

[0004] Current methods for preparing CDs suffer from cumbersome processes, long reaction times, and low fluorescence quantum yields. Therefore, there is an urgent need for a method to synthesize highly fluorescent CDs with different wavelengths of emission on a large scale. Summary of the Invention

[0005] The purpose of this invention is to provide a method for large-scale preparation of different fluorescent emitting carbon dots using solvent engineering. The method is simple, uses inexpensive and readily available raw materials, has a simple purification process, a short reaction time, and a high fluorescence quantum yield. It can be prepared on a large scale and has broad application prospects.

[0006] This invention provides a method for large-scale preparation of carbon dots with different fluorescence emission using solvent engineering, comprising the following steps:

[0007] S1. Dissolve aromatic anhydride derivatives and aromatic amine derivatives in a dispersion system of a predetermined ratio and disperse to obtain a dispersion.

[0008] S2. The dispersion obtained in step S1 is subjected to ultrasonic treatment for a preset time to obtain the ultrasonically treated dispersion;

[0009] S3. The dispersion obtained after ultrasonic treatment in step S2 is subjected to microwave-assisted heating. After a preset reaction time, it is cooled to room temperature, an aprotic solvent is added, and the mixture is centrifuged and filtered. Ultrapure water is then added to the supernatant, and the precipitate is collected to obtain fluorescent carbon dots (CDs).

[0010] Specifically, in step S1, the aromatic anhydride derivatives include one or more of benzoic anhydride, benzoic anhydride, p-toluenecarboxylic anhydride, 4-chlorobenzoic anhydride, 1,2,4,5-benzenetetracarboxylic anhydride, 2,4,6-trimethylbenzoic anhydride, 2,3,4,5,6-pentafluorobenzoic anhydride, 3-methylbenzene-1-carboxylic anhydride tetraiodo-2-sulfonic anhydride, 3-dimethylaminobenzoic anhydride, 4-trifluoromethylbenzoic anhydride, and biphenyl anhydride.

[0011] Furthermore, the aromatic anhydride derivative is preferably 1,2,4,5-benzenetetracarboxylic anhydride.

[0012] The aromatic amine derivatives include one or more of aniline, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, o-toluenediamine, toluenediamine, 3,4-toluenediamine, 4-fluoro-o-phenylenediamine, and 2-chloro-1,4-p-phenylenediamine.

[0013] Furthermore, the aromatic amine derivative is preferably o-phenylenediamine.

[0014] The molar ratio of the benzoic anhydride derivatives to the aniline derivatives is (100-1):1.

[0015] When the target product is blue light carbon dots, the molar ratio of benzoic anhydride derivatives to aniline derivatives is (100:1 to 20:1).

[0016] When the target product is a green carbon dot, the molar ratio of benzoic anhydride derivatives to aniline derivatives is (20:1 to 10:1).

[0017] When the target product is a yellow carbon dot, the molar ratio of benzoic anhydride derivatives to aniline derivatives is (10:1 to 5:2).

[0018] When the target product is a red carbon dot, the molar ratio of benzoic anhydride derivatives to aniline derivatives is (5:2 to 1:1).

[0019] The dispersion system includes one or more of the following: ethanol and water dispersion system, methanol and water dispersion system, tetrahydrofuran and water dispersion system, acetonitrile and water dispersion system, formamide and water dispersion system, N,N-dimethylformamide and water dispersion system.

[0020] Furthermore, the dispersion system is preferably an ethanol and water dispersion system.

[0021] Specifically, in step S2, the preset time for the ultrasonic treatment is 0 to 1 hour.

[0022] In step S3, the microwave-assisted heating reaction temperature is 100–250°C, and the reaction time is 0–30 min.

[0023] The aprotic solvent includes one or more of diethyl ether, tetrahydrofuran, dioxane, chloroform, dichloromethane, carbon tetrachloride, acetone, pyridine, acetonitrile, formamide, and dimethyl sulfoxide.

[0024] Furthermore, the aprotic solvent is preferably DMSO.

[0025] Specifically, the centrifugal filtration process conditions are as follows: centrifugation speed is 100-9000 rpm, centrifugation time is 0.1-1 h; filtration is performed using an organic phase microporous membrane; the pore size of the organic phase microporous membrane is 0.22-0.45 μm.

[0026] Furthermore, the centrifugation speed is preferably 3000 rpm, the centrifugation time is preferably 10 min, and the pore size of the organic phase microporous filter membrane is preferably 0.22 μm.

[0027] The beneficial effects of this invention are:

[0028] (1) The present invention discloses a method for large-scale preparation of different fluorescent emission carbon dots by solvent engineering. By adjusting the ratio of aromatic acid anhydride derivatives and aromatic amine derivatives, as well as the reaction time and reaction temperature, the emission wavelength of the prepared CDs is changed, and four narrow emission CDs with different fluorescence are prepared, realizing the large-scale preparation of blue, green, yellow and red CDs.

[0029] (2) The raw materials used in the method of the present invention are green, safe and readily available, the reaction conditions are mild, the preparation steps are simple, the reaction time is short, the post-processing is convenient and quick, and the equipment requirements are low.

[0030] (3) The CDs prepared by the method of the present invention have high yield and fluorescence quantum yield, uniform size, rich surface functional groups, and good photostability;

[0031] (4) The CDs of the present invention can be synthesized in large quantities in a short time and can be widely used in fields such as analysis and detection, information encryption, cell imaging and disease diagnosis and treatment. Attached Figure Description

[0032] Figure 1 This is a transmission electron microscope schematic diagram of the four narrow emission CDs emitting blue, green, yellow, and red light synthesized in Example 1;

[0033] Figure 2 This is a luminescence pattern of the narrow emission CDs synthesized in Example 1 under ultraviolet lamp irradiation;

[0034] Figure 3 The UV-Vis absorption spectrum of the narrow emission CDs synthesized in Example 1;

[0035] Figure 4The fluorescence spectrum of the narrow emission CDs synthesized in Example 1;

[0036] Figure 5 The wavelength-dependent fluorescence spectrum of the narrow emission CDs synthesized in Example 1;

[0037] Figure 6 The narrow emission CDs synthesized in Example 1 under xenon lamp irradiation (2W / cm²) -2 (Photostability test diagram)

[0038] Figure 7 The image shows the cytotoxicity test results of the narrow emission CDs synthesized in Example 1. Detailed Implementation

[0039] The present invention will be further described below with reference to an embodiment:

[0040] At room temperature, four groups of 1,2,4,5-phenyltetracarboxylic anhydride and o-phenylenediamine in different proportions were dissolved in a dispersion solution (300 mL) of ethanol and water.

[0041] In the first group, 100g of 1,2,4,5-phenyltetracarboxylic anhydride and 5g of o-phenylenediamine were used. The mixed dispersion was sonicated for 10 minutes, then microwaved at 200℃ for 10 minutes, and then naturally cooled to room temperature.

[0042] In the second group, 100g of 1,2,4,5-phenyltetracarboxylic anhydride and 6g of o-phenylenediamine were used. The mixed dispersion was sonicated for 10 minutes, then microwaved at 200℃ for 12 minutes, and then naturally cooled to room temperature.

[0043] In the third group, 100g of 1,2,4,5-phenyltetracarboxylic anhydride and 10g of o-phenylenediamine were used. The mixed dispersion was sonicated for 10 minutes, then microwaved at 200℃ for 16 minutes, and then naturally cooled to room temperature.

[0044] In the fourth group, 100g of 1,2,4,5-phenyltetracarboxylic anhydride and 45g of o-phenylenediamine were used. The mixed dispersion was sonicated for 10 minutes, then microwaved at 200℃ for 20 minutes, and then naturally cooled to room temperature.

[0045] After the four reactions were completed, the solvent was allowed to evaporate and dissolved in DMSO. The resulting solution was then centrifuged and filtered at 3000 rpm for 10 min. The supernatant was filtered through a 0.22 μm organic phase microporous membrane, and pure water was added to collect the precipitate, thus obtaining four sets of carbon dots.

[0046] The carbon dots obtained in the first group were B-CDs; the carbon dots obtained in the second group were G-CDs; the carbon dots obtained in the third group were G-CDs; and the carbon dots obtained in the fourth group were R-CDs.

[0047] The fluorescence quantum yields of B-CDs, G-CDs, Y-CDs, and R-CDs were 28.6%, 26.8%, 20.9%, and 7.8%, respectively.

[0048] The four sets of narrow-emission CDs prepared were observed by transmission electron microscopy, and the transmission electron microscopy images are shown below. Figure 1 As shown, the size of B-CDs is approximately ~2.1 nm, the size of G-CDs is approximately ~3.2 nm, the size of Y-CDs is approximately ~2.8 nm, and the size of R-CDs is approximately ~3.0 nm, with a uniform distribution.

[0049] The four sets of narrow-emission CDs prepared were excited by ultraviolet light irradiation, and the images are as follows. Figure 2 As shown, under ultraviolet light excitation, the four narrow emission CDs emit blue, green, yellow, and red light, respectively.

[0050] The UV-Vis absorption spectra of the four prepared narrow-emission CDs were obtained by UV-Vis absorption detection, as shown below. Figure 3 As shown in the figure. The UV-Vis absorption shows that the main absorption peaks of B-CDs are located at 236 nm and 276 nm, the main absorption peaks of G-CDs are located at 237 nm, 270 nm and 410 nm, the absorption peak of Y-CDs is located at 400 nm, and the absorption peaks of R-CDs are located at 640 nm and 670 nm.

[0051] Fluorescence spectra of the four prepared narrow-emission CDs were obtained, as shown in the following figures. Figure 4 As shown in the figure. The results show that the fluorescence emission peak of B-CDs is located at 430 nm with a half-width at half-maximum (WHM) of 53 nm; the fluorescence emission peak of G-CDs is located at 480 nm with a WHM of 36 nm; the fluorescence emission peak of Y-CDs is located at 530 nm with a WHM of 72 nm; and the fluorescence emission peak of R-CDs is located at 680 nm with a WHM of 26 nm.

[0052] Wavelength-dependent fluorescence spectroscopy was performed on the four prepared narrow-emission CDs to obtain wavelength-dependent fluorescence spectra, such as... Figure 5 As shown in the figure. The results show that none of the four CDs exhibited wavelength dependence.

[0053] The photostability of the four sets of narrow-emission CDs was tested, and the results are as follows: Figure 6 As shown in the figure, a comparison with sodium fluorescein reveals that all four CDs exhibit good photostability.

[0054] The four groups of narrow-emission CDs prepared were subjected to cytotoxicity tests, and the results are as follows: Figure 7 As shown, all four CDs exhibit good biocompatibility.

Claims

1. A method for solvent-engineering scale-up preparation of different fluorescent emission carbon dots, characterized in that, Comprising the following steps: S1. Dissolving 1,2,4,5-benzene tetracarboxylic anhydride and o-phenylenediamine in a dispersion system of 300 mL ethanol and water to obtain a dispersion; S2. Ultrasonic treating the dispersion obtained in step S1 for 10 min to obtain an ultrasonic treated dispersion; S3. Microwave-assisted heating the ultrasonic treated dispersion obtained in step S2, cooling to room temperature after presetting time, adding an aprotic solvent, centrifugal filtration, adding ultrapure water to the supernatant, and collecting the precipitate to obtain fluorescent emission carbon dots; When the target product is blue light carbon dots, 1,2,4,5-benzene tetracarboxylic anhydride is 100 g, o-phenylenediamine is 5 g, the reaction temperature of microwave-assisted heating in step S3 is 200℃, the preset time is 10 min, and the full width at half maximum of the obtained fluorescent emission carbon dots is 53 nm; When the target product is green light carbon dots, 1,2,4,5-benzene tetracarboxylic anhydride is 100 g, o-phenylenediamine is 6 g, the reaction temperature of microwave-assisted heating in step S3 is 200℃, the preset time is 12 min, and the full width at half maximum of the obtained fluorescent emission carbon dots is 36 nm; When the target product is yellow light carbon dots, 1,2,4,5-benzene tetracarboxylic anhydride is 100 g, o-phenylenediamine is 10 g, the reaction temperature of microwave-assisted heating in step S3 is 200℃, the preset time is 16 min, and the full width at half maximum of the obtained fluorescent emission carbon dots is 72 nm; When the target product is red light carbon dots, 1,2,4,5-benzene tetracarboxylic anhydride is 100 g, o-phenylenediamine is 45 g, the reaction temperature of microwave-assisted heating in step S3 is 200℃, the preset time is 20 min, and the full width at half maximum of the obtained fluorescent emission carbon dots is 26 nm.

2. The method of solvent-engineered scale-up production of carbon dots with different fluorescent emission according to claim 1, wherein, In step S3, the aprotic solvent includes one or more of diethyl ether, tetrahydrofuran, dioxane, chloroform, dichloromethane, carbon tetrachloride, acetone, pyridine, acetonitrile, formamide, dimethyl sulfoxide. 3.The method of claim 1, wherein the solvent-engineered mass production of carbon dots with different fluorescent emissions is characterized by, The process conditions of the centrifugal filtration are: centrifugal speed of 100-9000 rpm and centrifugal time of 0.1-1 h; organic phase microporous filter is used for filtration; the pore size of the organic phase microporous filter is 0.22-0.45 μm.

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