A room temperature rapid preparation method for highly fluorescent water-soluble sulfur quantum dots

Abstract

The present invention discloses a method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots at room temperature. At room temperature, sublimed sulfur is added to an organic amine and stirred until dissolved, followed by the addition of anhydrous ethanol to obtain a sulfur-containing precursor solution. Hydrogen peroxide is then added to the obtained sulfur-containing precursor solution to produce fluorescent sulfur quantum dots. The fluorescent sulfur quantum dots prepared by the present invention have a small particle size, good fluorescence quantum yield and water solubility, and are simple to prepare, requiring a short preparation time and low cost. The sulfur quantum dots prepared by this method have broad application prospects in the fields of fluorescent probes, bioimaging, and optoelectronic devices.

Description

Technical Field

[0001] The invention belongs to the technical field of nanomaterials, and in particular relates to a method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots at room temperature. Background Art

[0002] Fluorescent quantum dots, due to their excellent optical properties, have shown promising application prospects in many fields such as fluorescent labeling, catalysis, and optoelectronic devices. Compared with fluorescent quantum dots containing metal elements, fluorescent quantum dots without metal elements are more suitable for practical applications due to their better biocompatibility. Sulfur quantum dots are a representative type of fluorescent quantum dots without metal elements. Currently, sulfur quantum dots can be prepared by methods such as acid etching, ultrasonication, and hydrothermal methods. However, these preparation methods often have complex preparation processes, expensive preparation equipment, and harsh preparation conditions, which seriously limit the practical application of fluorescent sulfur quantum dots. On the other hand, these preparation methods usually require preparation cycles of several hours, more than ten hours, or even more than a hundred hours, which is not suitable for industrial production and commercial applications, and also causes some energy consumption. Therefore, the invention of a method for rapidly preparing fluorescent sulfur quantum dots at room temperature using elemental sulfur can not only achieve simple and rapid industrial preparation of fluorescent sulfur quantum dots, but also further promote the theoretical research and practical application of fluorescent sulfur quantum dots. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems existing in the current field of fluorescent sulfur quantum dots, such as complex preparation methods, long preparation time, and harsh preparation conditions (such as hydrothermal / solvothermal preparation methods under high temperature and high pressure, ultrasonic preparation methods, microwave treatment preparation methods, and heating preparation methods under an oxygen atmosphere), and to provide a room temperature rapid preparation method for highly fluorescent water-soluble sulfur quantum dots, so as to further promote the application and development of fluorescent sulfur quantum dots.

[0004] The specific steps are:

[0005] (1) adding sublimed sulfur to organic amine to dissolve it, and then adding anhydrous ethanol to obtain a sulfur-containing precursor solution;

[0006] (2) Adding hydrogen peroxide to the sulfur-containing precursor solution obtained in step (1) to prepare fluorescent sulfur quantum dots.

[0007] The organic amine is one of diethylenetriamine, ethylenediamine, butylamine and / or oleylamine.

[0008] Said steps (1) and (2) are carried out at a temperature of 15°C to 30°C, and more preferably at room temperature.

[0009] The ratio of the sublimated sulfur to the organic amine is preferably 1:2-1:30, more preferably 1:7-1:25, and most preferably 1:10-1:20.

[0010] The addition ratio of the sublimed sulfur and anhydrous ethanol is preferably 1:2-1:30, and more preferably 1:7-1:25.

[0011] The stirring until dissolved does not necessarily mean stirring, and can be any method of dissolving the organic amine.

[0012] After the sublimed sulfur is dissolved in the organic amine, there is no special requirement for when to add anhydrous ethanol.

[0013] The concentration of the hydrogen peroxide is preferably 1 to 10 mol / L, more preferably 4 to 6 mol / L, and most preferably 5 mol / L.

[0014] The ratio of the sublimed sulfur to hydrogen peroxide is preferably 1:3 to 1:25, and more preferably 1:8 to 1:20.

[0015] Beneficial effects:

[0016] The outstanding advantage of this preparation method is that sublimed sulfur can be quickly converted into fluorescent sulfur quantum dots by simply stirring at room temperature. It has the advantages of simple preparation, easy operation, and rapid preparation. The prepared fluorescent sulfur quantum dots were observed by transmission electron microscopy to have the morphology of monodispersed spherical particles with a size of 1.5-3.5 nanometers. The results obtained by Raman spectrometry confirmed that they were sulfur quantum dots. The prepared sulfur quantum dots have excellent water dispersibility and can emit bright blue fluorescence under 365-nanometer ultraviolet light. The results of fluorescence spectrometry testing further confirmed their excellent photoluminescence properties, with a fluorescence quantum yield of up to 23.6%. In addition, the sulfur quantum dots prepared by this method have broad application prospects in fluorescent probes, biological imaging, and optoelectronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a transmission electron microscope photograph of fluorescent sulfur quantum dots rapidly prepared at room temperature in Example 1 of a method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots at room temperature;

[0018] Figure 2 This is a Raman spectrum of fluorescent sulfur quantum dots rapidly prepared at room temperature in Example 1 of a method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots at room temperature;

[0019] Figure 3This is a photograph of an aqueous dispersion of fluorescent sulfur quantum dots rapidly prepared at room temperature under sunlight (left) and 365 nm ultraviolet light (right) in Example 1 of a method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots at room temperature;

[0020] Figure 4 This is a fluorescence spectrum of fluorescent sulfur quantum dots rapidly prepared at room temperature (excitation wavelength is 365 nanometers) in Example 1 of a method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots at room temperature;

[0021] Figure 5 This is a transmission electron microscope photograph of fluorescent sulfur quantum dots rapidly prepared at room temperature in Example 2 of a method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots at room temperature;

[0022] Figure 6 This is a photograph of an aqueous dispersion of fluorescent sulfur quantum dots rapidly prepared at room temperature under sunlight (left) and 365 nm ultraviolet light (right) in Example 2 of a method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots at room temperature;

[0023] Figure 7 This is a fluorescence spectrum of fluorescent sulfur quantum dots rapidly prepared at room temperature (excitation wavelength is 365 nanometers) in Example 2 of a method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots at room temperature;

[0024] Figure 8 This is a transmission electron microscope photograph of fluorescent sulfur quantum dots rapidly prepared at room temperature in Example 6 of a method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots at room temperature;

[0025] Figure 9 This is a photograph of an aqueous dispersion of fluorescent sulfur quantum dots rapidly prepared at room temperature under sunlight (left) and 365 nm ultraviolet light (right) according to Example 6 of a method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots at room temperature;

[0026] Figure 10 This is a fluorescence spectrum of fluorescent sulfur quantum dots quickly prepared at room temperature (excitation wavelength is 365 nanometers) in Example 6 of a method for quickly preparing highly fluorescent water-soluble sulfur quantum dots at room temperature. DETAILED DESCRIPTION

[0027] Example 1: (Standard Amount)

[0028] (1) Add 1 g of sublimed sulfur to 10 g of ethylenediamine and stir until dissolved. Then add 10 g of anhydrous ethanol to obtain a sulfur-containing precursor mixed solution.

[0029] (2) Add 15 g of 5 mol / L hydrogen peroxide to the sulfur-containing mixed precursor solution obtained in step (1) to obtain fluorescent sulfur quantum dots.

[0030] Experimental results: The prepared fluorescent sulfur quantum dots were observed to be monodispersed spherical particles with a size of 1.5-3.5 nanometers ( Figure 1 : Scale bar 50 nm); The results obtained by Raman spectroscopy test confirmed that it is sulfur quantum dots ( Figure 2 The prepared sulfur quantum dots have excellent water dispersibility and can emit bright blue fluorescence under 365 nm ultraviolet light ( Figure 3 and Figure 4 ), the fluorescence quantum yield of the fluorescent sulfur quantum dots obtained under this condition can reach 23.6%.

[0031] Example 2: (minimum amount)

[0032] (1) Add 3 g of sublimed sulfur to 21 g of ethylenediamine and stir until dissolved. Then add 21 g of anhydrous ethanol to obtain a sulfur-containing precursor mixed solution.

[0033] (2) Add 54 g of 5 mol / L hydrogen peroxide to the sulfur-containing precursor mixed solution obtained in step (1) to obtain fluorescent sulfur quantum dots.

[0034] Experimental results: The prepared fluorescent sulfur quantum dots were observed to be monodispersed spherical particles with a size of 1.5-3.5 nanometers ( Figure 5 : Scale bar 100 nm); The prepared sulfur quantum dots have excellent water dispersibility and can emit bright blue fluorescence under 365 nm ultraviolet light ( Figure 6 and Figure 7 ).

[0035] Example 3:

[0036] (1) Add 2 g of sublimed sulfur to 30 g of diethylenetriamine and stir until dissolved. Then add 30 g of anhydrous ethanol to obtain a sulfur-containing precursor mixed solution.

[0037] (2) Add 40 g of 5 mol / L hydrogen peroxide to the sulfur-containing precursor mixed solution obtained in step (1) to obtain fluorescent sulfur quantum dots.

[0038] Embodiment 4:

[0039] (1) Add 5 g of sublimed sulfur to 45 g of diethylenetriamine and stir until dissolved. Then add 45 g of anhydrous ethanol to obtain a sulfur-containing precursor mixed solution.

[0040] (2) Add 40 g of 5 mol / L hydrogen peroxide to the sulfur-containing precursor mixed solution obtained in step (1) to obtain fluorescent sulfur quantum dots.

[0041] Example 5:

[0042] (1) Add 1.5 g of sublimed sulfur to 30 g of butylamine and stir until dissolved. Then add 30 g of anhydrous ethanol to obtain a sulfur-containing precursor mixed solution.

[0043] (2) Add 24 g of 5 mol / L hydrogen peroxide to the sulfur-containing precursor mixed solution obtained in step (1) to obtain fluorescent sulfur quantum dots.

[0044] Example 6: (maximum amount)

[0045] (1) 4 g of sublimed sulfur was added to 100 g of oleylamine and stirred until dissolved. Then, 100 g of anhydrous ethanol was added to obtain a sulfur-containing precursor mixed solution.

[0046] (2) Add 68 g of 5 mol / L hydrogen peroxide to the sulfur-containing precursor mixed solution obtained in step (1) to obtain fluorescent sulfur quantum dots.

[0047] Experimental results: The prepared fluorescent sulfur quantum dots were observed to be monodispersed spherical particles with a size of 1.5-3.5 nanometers ( Figure 8 : Scale bar 50 nm); The prepared sulfur quantum dots have excellent water dispersibility and can emit bright blue fluorescence under 365 nm ultraviolet light ( Figure 9 and Figure 10 ).

[0048] Example 7:

[0049] (1) 0.5 g of sublimed sulfur was added to 11 g of oleylamine and stirred until dissolved. Then, 11 g of anhydrous ethanol was added to obtain a sulfur-containing precursor mixed solution.

[0050] (2) Add 7 g of 5 mol / L hydrogen peroxide to the sulfur-containing precursor mixed solution obtained in step (1) to obtain fluorescent sulfur quantum dots.

Claims

1. A rapid preparation method of highly fluorescent water-soluble sulfur quantum dots, comprising: (1) adding sublimed sulfur to organic amine to dissolve it, and then adding anhydrous ethanol to obtain a sulfur-containing precursor solution; (2) adding hydrogen peroxide to the sulfur-containing precursor solution obtained in step (1) to prepare fluorescent sulfur quantum dots; The organic amine is diethylenetriamine, ethylenediamine, butylamine or oleylamine; The steps (1) and (2) are carried out at a temperature of 15°C to 30°C.

2. The method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots according to claim 1, wherein: The steps (1) and (2) are carried out at room temperature.

3. The method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots according to claim 2, wherein: The ratio of the sublimated sulfur to the organic amine is 1:2-1:

30.

4. The method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots according to claim 3, wherein: The ratio of the sublimated sulfur to the organic amine is 1:7 to 1:

25.

5. The method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots according to claim 3, wherein: The ratio of the sublimated sulfur to the anhydrous ethanol is 1:2-1:

30.

6. The method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots according to claim 5, wherein: The ratio of the sublimed sulfur and anhydrous ethanol is 1:7~1:25; The concentration of the hydrogen peroxide is 1 to 10 mol / L.

7. The method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots according to claim 6, wherein: The concentration of hydrogen peroxide is 4 to 6 mol / liter; The ratio of the sublimated sulfur to hydrogen peroxide is 1:3 to 1:

25.

8. The method for rapidly preparing highly fluorescent water-soluble sulfur quantum dots according to claim 7, wherein: The ratio of the sublimated sulfur to hydrogen peroxide is 1:8 to 1:20.

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