CN103588178B - Technology for synthesizing sulfur quantum dots through oil-water interface method - Google Patents

Abstract

The invention discloses a method for synthesizing sulfur quantum dots by an oil-water interface method, comprising the following steps: (1) preparation of metal sulfide quantum dots; (2) configuration of nitric acid solution; (3) preparation of sulfur quantum dots. The present invention uses oleic acid as a solvent to prepare oil-soluble metal sulfide quantum dots, and uses the n-hexane solution of metal sulfide as the oil phase, and the nitric acid aqueous solution as the water phase. After the two phases are mixed, the nitric acid can be converted into Sulfur ions are oxidized to elemental sulfur, and metal sulfide quantum dots are used as templates to make the particle size distribution of the prepared sulfur quantum dots uniform. The oil-water interface slows down the reaction speed, making the sulfur nanoparticles dispersed and small in size. The present invention adopts the above technical scheme, and through the oil-water interface reaction, the n-hexane solution of metal sulfide is used as the oil phase, and the nitric acid solution is used as the water phase to synthesize sulfur quantum dots. The whole reaction condition is mild, the operation is simple, the particle size is controllable, and it is easy to promote.

Description

A kind of method for synthesizing sulfur quantum dots by oil-water interface method

technical field

The invention belongs to the technical field of nanometer material preparation, in particular to a method for synthesizing sulfur quantum dots by an oil-water interface method.

Background technique

Quantum dots (Quantum dots) are composed of a limited number of atoms, quasi-zero-dimensional nanomaterials with three dimensions smaller than 10nm. Compared with other nanomaterials, the movement of internal electrons in all directions is restricted, so quantum confinement The quantum confinement effect is particularly significant. As a new type of semiconductor fluorescent nanomaterial, it has many excellent properties due to the surface effect, dielectric effect and quantum effect caused by its special nanostructure. Sensors and other fields to be applied and developed.

Sulfur is the main component of sulfur in traditional Chinese medicine, which is commonly used to treat skin diseases such as scabies, tinea capitis, acne, seborrheic dermatitis, rosacea, pityriasis simplex and chronic eczema. At present, the raw material sulfur powder used in the preparation of clinically used sulfur preparations is all micro-nano particles, with large particle size, wide particle size distribution, and small specific surface area. There are poor skin absorption, low bioavailability, and unstable antibacterial activity. , inconvenient use and other shortcomings have influenced its curative effect and use to a certain extent. Researchers have developed nano-sulfur (1-100nm) with small particle size and large specific surface area to overcome some shortcomings of micro-sulfur. However, sulfur quantum dots have smaller particle size (<10nm), uniform particle size, and higher chemical activity. , can effectively solve the problems existing in the application process of micro-nanosulfur, and has fluorescent properties. Its preparation, characteristics and potential applications have attracted the attention of researchers in the fields of chemistry and medicine.

At present, the main methods for preparing nano-sulfur are microemulsion method and chemical vapor deposition method. Patent name: Preparation method of high-purity nano-sulfur (patent application number: 03128015.3) discloses a method for preparing elemental sulfur by chemical vapor deposition. This method has problems such as cumbersome operation, high cost, wide particle size distribution, and difficulty in regulation. ; Patent name: Preparation of nano-sulfur particles by microemulsion method (patent application number: 201010220221.1) discloses a method for preparing elemental sulfur by microemulsion method. This method has complex reaction system, cumbersome operation, large particle size of nano-sulfur and wide distribution And other issues. The reason for this problem is that the homogeneous reaction speed is fast, and the specific surface area of nano-sulfur is large, so that the particles are easily adsorbed and agglomerated, thereby forming large agglomerated particles.

Contents of the invention

The technical problem to be solved by the present invention is to provide a kind of oil-water interface method to synthesize sulfur quantum dots, which uses metal sulfide quantum dots as raw materials and can obtain fluorescence properties that conventional nano-sulfur does not have only through a simple oil-water interface reaction. point method.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for synthesizing sulfur quantum dots by an oil-water interface method, comprising the following steps:

(1) Preparation of metal sulfide quantum dots: add metal chloride to oleic acid to prepare a mixed solution of oleic acid metal chloride with a concentration of 0.1-0.5mol/L, and stir magnetically at 90-170°C for 25-35min Finally, in the oleic acid metal chloride mixed solution, add a concentration of 0.2-0.6mol/L oleic acid solution dissolved with elemental sulfur, the volume of the oleic acid metal chloride mixed solution and the oleic acid solution dissolved with elemental sulfur The ratio is 2:1, and magnetically stirred at 150-320°C for 55-65min to obtain the crude product of metal sulfide quantum dots. Add absolute ethanol to the crude product of metal sulfide quantum dots to precipitate the metal sulfide quantum dots. Centrifuge at 8000-12000 rpm, wash the precipitate with absolute ethanol for more than three times, vacuum-dry the precipitate at 45-55°C to obtain metal sulfide quantum dots, dissolve the metal sulfide quantum dots in n-hexane, and The mass of the metal sulfide quantum dots and the volume ratio of n-hexane are 1:2-4 to obtain the n-hexane solution of the metal sulfide quantum dots;

(2) Configuration of nitric acid solution: dissolving concentrated nitric acid with a mass fraction of 65% in ultrapure water, stirring to form a nitric acid solution with a concentration of 0.04-0.06mol/L;

(3) Preparation of sulfur quantum dots: Add metal sulfide quantum dots n-hexane solution to nitric acid solution, the molar ratio of metal sulfide quantum dots sulfur ions to nitric acid in the metal sulfide quantum dots n-hexane solution is 1:2.67 -20, magnetically stirred at room temperature for 36 hours to obtain an emulsion, and after separating the emulsion, the oil phase was obtained as n-hexane solution containing sulfur quantum dots, and the sulfur quantum dots were obtained by rotary evaporation.

The metal in the metal chloride described in the step (1) is a transition metal element.

The transition metal element is Fe, Mn, Zn, Cu, Cd or Ag.

The molar ratio of the sulfide ions of the metal sulfide quantum dots in the n-hexane solution of the metal sulfide quantum dots described in the step (3) to nitric acid is 1:2.67-10.

The ion reaction equation of sulfur ion and nitric acid solution is:

3S ^2- +8H ⁺ +2NO ₃ ^- ＝3S↓+2NO↑+4H ₂ O

The present invention uses oleic acid as a solvent to prepare oil-soluble metal sulfide quantum dots, and uses the n-hexane solution of metal sulfide as the oil phase, and the nitric acid aqueous solution as the water phase. After the two phases are mixed, the nitric acid can be converted into Sulfur ions are oxidized to elemental sulfur, and metal sulfide quantum dots are used as templates to make the particle size distribution of the prepared sulfur quantum dots uniform. The oil-water interface slows down the reaction speed, making the sulfur nanoparticles dispersed and small in size.

The present invention adopts the above technical scheme, through the oil-water interface reaction, using the n-hexane solution of metal sulfide as the oil phase, and the nitric acid solution as the water phase to synthesize sulfur quantum dots. The whole reaction condition is mild, the operation is simple, the particle size is controllable, and it is easy to promote.

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments:

Fig. 1 is the fluorescence spectrogram of the zinc sulfide quantum dot prepared in the method for the synthetic sulfur quantum dot of a kind of oil-water interface method of the present invention;

Fig. 2 is the fluorescence spectrogram of the sulfur quantum dot prepared by zinc sulfide quantum dot by the method for the synthesis of sulfur quantum dot by a kind of oil-water interface method of the present invention;

Fig. 3 is the fluorescence spectrogram of the sulfur quantum dots prepared by the manganese sulfide quantum dots for a method of synthesizing sulfur quantum dots by the oil-water interface method of the present invention;

Fig. 4 is the fluorescent spectrogram of the sulfur quantum dot that a kind of oil-water interface method of the present invention synthesizes sulfur quantum dot by the cadmium sulfide quantum dot;

Fig. 5 is the high power transmission electron microscope picture of the method cadmium sulfide quantum dot of a kind of oil-water interface method of the present invention synthetic sulfur quantum dot;

Fig. 6 is a high-magnification transmission electron microscope image of sulfur quantum dots prepared by a method for synthesizing sulfur quantum dots by an oil-water interface method of the present invention from cadmium sulfide quantum dots;

Detailed ways

The present invention will be described in further detail below in conjunction with specific embodiment:

A method for synthesizing sulfur quantum dots by an oil-water interface method, comprising the following steps:

(1) Preparation of metal sulfide quantum dots: add metal chloride to oleic acid to prepare a mixed solution of oleic acid metal chloride with a concentration of 0.1-0.5mol/L, and stir magnetically at 90-170°C for 25-35min Finally, in the oleic acid metal chloride mixed solution, add a concentration of 0.2-0.6mol/L oleic acid solution dissolved with elemental sulfur, the volume of the oleic acid metal chloride mixed solution and the oleic acid solution dissolved with elemental sulfur The ratio is 2:1, and magnetically stirred at 150-320°C for 55-65min to obtain the crude product of metal sulfide quantum dots. Add absolute ethanol to the crude product of metal sulfide quantum dots to precipitate the metal sulfide quantum dots. Centrifuge at 8000-12000 rpm, wash the precipitate with absolute ethanol for more than three times, vacuum-dry the precipitate at 45-55°C to obtain metal sulfide quantum dots, dissolve the metal sulfide quantum dots in n-hexane, and The mass of metal sulfide quantum dots and the volume ratio of normal hexane are 1:2-4, obtain the normal hexane solution of metal sulfide quantum dots;

(2) Configuration of nitric acid solution: dissolving concentrated nitric acid with a mass fraction of 65% in ultrapure water, stirring to form a nitric acid solution with a concentration of 0.04-0.06mol/L;

(3) Preparation of sulfur quantum dots: Add metal sulfide quantum dots n-hexane solution to nitric acid solution, the molar ratio of metal sulfide quantum dots sulfur ions to nitric acid in the metal sulfide quantum dots n-hexane solution is 1:2.67 -20, magnetically stirred at room temperature for 36 hours to obtain an emulsion, and after separating the emulsion, the oil phase was obtained as n-hexane solution containing sulfur quantum dots, and the sulfur quantum dots were obtained by rotary evaporation. The molar ratio of sulfur ions in the n-hexane solution of metal sulfide quantum dots to nitrate radicals in the nitric acid solution is 1:2.67-20, which can ensure that all sulfur ions are converted into simple sulfur.

The metal in the metal chloride described in the step (1) is a transition metal element.

The transition metal element is Fe, Mn, Zn, Cu, Cd or Ag.

The molar ratio of the sulfide ions of the metal sulfide quantum dots in the n-hexane solution of the metal sulfide quantum dots described in the step (3) to nitric acid is 1:2.67-10.

Example 1

Add 2mmol of zinc chloride to 10mL of oleic acid to prepare a mixed solution of oleic acid metal chloride with a concentration of 0.2mol/L. After magnetic stirring at 170°C for 30min, add 5mL A 0.6mol/L oleic acid solution with elemental sulfur dissolved therein was magnetically stirred at 320°C for 60 minutes to obtain a crude product of metal sulfide quantum dots, and absolute ethanol was added to the crude product of metal sulfide quantum dots to make the metal sulfide quantum dots Spot the precipitate, centrifuge at 10000rpm, wash the precipitate with absolute ethanol for more than three times, and vacuum dry the precipitate at 50°C to obtain a white solid that is zinc sulfide quantum dots. Dissolve 4.85mg of zinc sulfide quantum dots in 9.7mL In n-hexane, zinc sulfide quantum dot n-hexane solution was obtained as the oil phase of the interface reaction; another nitric acid solution with a concentration of 0.05mol/L was prepared as the water phase of the interface reaction, and 20mL nitric acid solution and zinc sulfide quantum dot n-hexane were taken The solutions were mixed, stirred magnetically at room temperature for 36 hours to obtain an emulsion, and the oil phase was obtained after liquid separation of the emulsion, which was n-hexane solution containing sulfur quantum dots, and the sulfur quantum dots were obtained by rotary evaporation.

It can be seen from Fig. 1 that the zinc sulfide quantum dot has three emission peaks, the excitation wavelength is 214nm, and the maximum emission wavelength is 491nm. Figure 2 is the fluorescence spectrum of sulfur quantum dots prepared by zinc sulfide quantum dots. It can be seen from the figure that the excitation wavelength is 226nm and the emission wavelength is 340nm, which is significantly different from the peak position of zinc sulfide quantum dots, indicating that zinc sulfide quantum dots The reaction of quantum dots with nitric acid produces sulfur quantum dots with fluorescent properties.

Example 2

Add 5mmol of manganese chloride to 10mL of oleic acid to prepare a mixed solution of oleic acid metal chloride with a concentration of 0.5mol/L. After magnetically stirring at 120°C for 25min, add 5mL A 0.2mol/L oleic acid solution with elemental sulfur dissolved therein was magnetically stirred at 280°C for 55 minutes to obtain the crude product of metal sulfide quantum dots, and absolute ethanol was added to the crude product of metal sulfide quantum dots to make the metal sulfide quantum dots Spot the precipitate, centrifuge at 8000rpm, wash the precipitate with absolute ethanol for more than three times, and vacuum-dry the precipitate at 45°C to obtain a black solid that is manganese sulfide quantum dots. Dissolve 26.1mg of manganese sulfide quantum dots in 78.3mL In n-hexane, manganese sulfide quantum dot n-hexane solution was obtained as the oil phase of the interfacial reaction; another nitric acid solution with a concentration of 0.04mol/L was prepared as the aqueous phase of the interfacial reaction, and 20mL of nitric acid solution and manganese sulfide quantum dot n-hexane The solutions were mixed, stirred magnetically at room temperature for 36 hours to obtain an emulsion, and the oil phase was obtained after liquid separation of the emulsion, which was n-hexane solution containing sulfur quantum dots, and the sulfur quantum dots were obtained by rotary evaporation. It can be seen from Figure 1 that the excitation wavelength of the sulfur quantum dots is 226nm, and the emission wavelength is 340nm.

It can be seen from Figure 3 that the excitation wavelength of the sulfur quantum dots is 340nm, and the emission wavelength is 428nm, indicating that the sulfur quantum dots prepared from the manganese sulfide quantum dots have fluorescence properties.

Example 3

Add 1mmol of cadmium chloride to 10mL of oleic acid to prepare a mixed solution of oleic acid metal chloride with a concentration of 0.1mol/L. After magnetic stirring at 90°C for 35min, add 5mL A 0.4mol/L oleic acid solution with elemental sulfur dissolved therein was magnetically stirred at 150°C for 65 minutes to obtain the crude product of metal sulfide quantum dots, and absolute ethanol was added to the crude product of metal sulfide quantum dots to make the metal sulfide quantum dots Spot the precipitate, centrifuge at 12000rpm, wash the precipitate with absolute ethanol for more than three times, and vacuum dry the precipitate at 55°C to obtain a yellow solid that is cadmium sulfide quantum dots. Dissolve 8.64mg of zinc sulfide quantum dots in 34.6mL In n-hexane, cadmium sulfide quantum dot n-hexane solution was obtained as the oil phase of the interface reaction; another nitric acid solution with a concentration of 0.06mol/L was prepared as the water phase of the interface reaction, and 20mL of nitric acid solution and cadmium sulfide quantum dot n-hexane The solutions were mixed, stirred magnetically at room temperature for 36 hours to obtain an emulsion, and the oil phase was obtained after liquid separation of the emulsion, which was n-hexane solution containing sulfur quantum dots, and the sulfur quantum dots were obtained by rotary evaporation.

It can be seen from Figure 4 that the excitation wavelength of the sulfur quantum dots is 354nm, and the emission wavelength is 431nm, indicating that the sulfur quantum dots prepared by the manganese sulfide quantum dots have fluorescence characteristics. Figure 5 is a high-magnification transmission electron microscope image of cadmium sulfide quantum dots, from which it can be estimated that the average particle size of cadmium sulfide quantum dots is 2.9nm. Figure 6 is a high-magnification transmission electron microscope image of sulfur quantum dots prepared from cadmium sulfide sulfur quantum dots, from which it can be estimated that the average particle size of sulfur quantum dots prepared from cadmium sulfide quantum dots is 1.6nm.

Claims (4)

1. a method for water-oil interface method synthesis sulphur quantum dot, is characterized in that: comprise the following steps:

(1) preparation of metal sulfide quantum dots: add metal chloride in oleic acid, be made into the oleic acid metal chloride mixed solution that concentration is 0.1-0.5mol/L, after 90-170 DEG C of lower magnetic force stirs 25-35min, the oleic acid solutions being dissolved with elemental sulfur that concentration is 0.2-0.6 mol/L is added in oleic acid metal chloride mixed solution, described oleic acid metal chloride mixed solution is 2:1 with the volume ratio of the oleic acid solutions being dissolved with elemental sulfur, 55-65 min is stirred at 150-320 DEG C of lower magnetic force, obtain metal sulfide quantum dots crude product, in metal sulfide quantum dots crude product, add dehydrated alcohol makes metal sulfide quantum dots precipitate, centrifugation under rotating speed 8000-12000rpm, obtain precipitation absolute ethanol washing more than three times, at 45-55 DEG C, vacuum-drying is carried out to precipitation and namely obtain metal sulfide quantum dots, metal sulfide quantum dots is dissolved in normal hexane, the quality of described metal sulfide quantum dots and the volume ratio of normal hexane are 1mg:2-4mL, obtain metal sulfide quantum dots hexane solution,

(2) configuration of salpeter solution: by massfraction be 65% concentrated nitric acid be dissolved in ultrapure water, be namely made into the salpeter solution that concentration is 0.04-0.06 mol/L after stirring;

(3) preparation of sulphur quantum dot: metal sulfide quantum dots hexane solution is joined in salpeter solution, in metal sulfide quantum dots hexane solution, the sulfonium ion of metal sulfide quantum dots and the mol ratio of nitric acid are 1:2.67-20, room temperature lower magnetic force stirs 36h and obtains emulsion, obtaining oil phase after carrying out separatory to emulsion is hexane solution containing sulphur quantum dot, rotary evaporation, namely obtains sulphur quantum dot.

2. the method for water-oil interface method synthesis sulphur quantum dot according to claim 1, is characterized in that: the metal in the metal chloride described in described step (1) is transition metal.

3. the method for water-oil interface method synthesis sulphur quantum dot according to claim 2, is characterized in that: described transition metal is Fe, Mn, Zn, Cu, Cd or Ag.

4. the method for water-oil interface method synthesis sulphur quantum dot according to claim 1, is characterized in that: in the metal sulfide quantum dots hexane solution described in described step (3), the sulfonium ion of metal sulfide quantum dots and the mol ratio of nitric acid are 1:2.67-10.