A method for synthesizing small-sized organic nanocrystals using cadmium telluride quantum dots and its preparation method

Abstract

The present invention relates to a method for synthesizing small-sized organic nanocrystals using cadmium telluride quantum dots, and belongs to the field of nano synthesis technology. The method uses functionalized quantum dots as seeds to synthesize organic molecular crystals through a seed growth method, and the synthesized organic nanocrystals have uniform sizes, and the sizes are all around 30nm. The method is simple and universal, and provides a new path for accurately controlling the size of organic molecular crystals.

Description

Technical Field

[0001] The invention relates to the technical field of organic nanocrystal material synthesis, in particular to synthesizing organic nanocrystals by using a seed growth method. Background Art

[0002] The application of nanomaterials has a long history. Humans first used soot containing nanoscale (<1mm) carbon particles as a colorant, while colloidal gold particles have been used as pigments since the Middle Ages. After decades of development in nanotechnology, the application of nanomaterials in various fields has increased. In particular, organic molecular crystal materials, as a new type of functional material, have been widely used in flexible electronics, biomedicine, high-energy materials, and optics. Because organic molecular crystals are usually formed by the combination of various non-covalent interactions between organic molecules (such as hydrogen bonds, electrostatics, hydrophobicity, van der Waals forces, or π-π interactions), such a weak driving force makes organic molecular crystals more sensitive to external stimuli or microenvironmental changes, which is conducive to their application in on-demand response to temperature, pH, or light irradiation. In addition, organic molecules have the characteristics of strong structural tailoring and good processability, and multiple applications can be achieved by adjusting the structural parameters of organic molecules.

[0003] Although the preparation of micron-sized organic crystals has been widely studied, nano-sized organic crystals remain a huge synthetic challenge. Traditional methods for synthesizing organic molecular crystals include solvent replacement and rapid cooling methods, and most of the crystals obtained using these methods are micron-sized with a wide size distribution.

[0004] Moreover, as the size of organic crystals decreases, their specific surface area also increases significantly. When the size of organic crystals decreases from 1 μm to 10 nm, the particle size changes by 100 times, but when converted into volume, it will increase by 10 times. 6 If the size of the generated organic nanocrystals is not uniform enough, most of the products will exist in the form of large-sized crystals, and the small-sized crystals will account for a very low material ratio. At the same time, large-sized crystals also reduce the surface effect. Therefore, when pursuing the minimum limit of molecular crystals, the uniformity of the crystals is a key factor.

[0005] For the above reasons, it is crucial to develop a method to synthesize small and uniform organic nanocrystals. Summary of the invention

[0006] The technical problem solved by the invention is to provide a method for preparing small and uniform organic nanocrystals.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is: a method for preparing small-sized organic nanocrystals, the preparation steps are as follows:

[0008] Step (1): synthesizing CdTe quantum dots;

[0009] Step (2): pre-incubating the CdTe quantum dots with organic molecules;

[0010] Step (3): placing the solution obtained in step (2) into a poor solution containing a surfactant, wherein the surfactant is sodium dodecyl sulfate;

[0011] Step (4): dissolving the organic molecules in step (2) in a good solvent, adding the solution to the solution containing functionalized quantum dots obtained in step (3), aging for 7-12 hours, and centrifugation purification to obtain small-sized organic nanocrystals.

[0012] Preferably, the preparation method of the quantum dots in step (1) is as follows: 0.255g of tellurium powder and 0.0600g of sodium borohydride are put into a flask containing 10mL of H2O and reacted in a constant temperature water bath at 55°C. The reaction process requires continuous introduction of N2 and vigorous stirring. The reaction is completed when the solution changes from black to dark purple; then a precursor is prepared, 0.0913g of cadmium chloride is weighed and put into a beaker, 66.5μL of thioglycolic acid and 50mL of deionized water are added, and the solution is stirred with a glass rod from clear and transparent to white turbid; 2mol / L sodium hydroxide solution is added to adjust the pH of the solution to 9-10 (the solution begins to change from white turbidity to clear and transparent at pH=7); the dark purple solution is passed through N2 for 30min and then rapidly heated to 100°C, and then 4mL of the newly prepared precursor solution is rapidly added thereto, reflux is started and continuous stirring is performed. After reacting for 20min, the reaction stock solution is rotary evaporated to dry to obtain CdTeQDs, which are stored in deionized water.

[0013] Preferably, the volume of quantum dots in step (2) is 50 μL; the organic molecule in step (2) is 9-fluorenone, dissolved in tetrahydrofuran at a concentration of 2 mM and a volume of 10 μL; the organic molecule in step (3) is 9-fluorenone, and the volume is 50 μL.

[0014] Preferably, the organic molecule in step (2) is 1,1,2,3,4,5-hexaphenylthiole or trans,trans-1,4-stilbene.

[0015] Preferably, the incubation time in step (2) is 2 h, the temperature is 60° C., and the organic molecules are dissolved in the tetrahydrofuran solution.

[0016] Preferably, the poor solvent in step (3) is ultrapure water with a volume of 400 μL, and the surfactant contained in the ultrapure water is sodium dodecyl sulfate with a concentration of 3.6 mM.

[0017] Preferably, the centrifugal speed in step (3) is 12500 rpm, and the centrifugation is performed for 10 min. Preferably, the good solvent in step (4) is tetrahydrofuran.

[0018] In order to solve the above technical problem, the present invention proposes another technical solution: small-sized organic nanocrystals prepared by any of the above methods.

[0019] A method for synthesizing small-sized organic nanocrystals using quantum dots comprises the following steps:

[0020] (1) Preparation method of CdTe quantum dots. 0.255g of tellurium powder and 0.0600g of sodium borohydride were put into a flask containing 10mL of H2O and reacted in a constant temperature water bath at 55°C. N2 was continuously introduced and stirred vigorously during the reaction process. The reaction was completed when the solution changed from black to dark purple. Then, the precursor was prepared. 0.0913g of cadmium chloride was weighed and put into a beaker. 66.5μL of thioglycolic acid and 50mL of deionized water were added. The solution was stirred with a glass rod from clear to white turbid. 2mol / L sodium hydroxide solution was added to adjust the pH of the solution to 9-10 (pH=7, the solution began to change from white turbidity to clear). After N2 was introduced into the dark purple solution for 30min, it was quickly heated to 100°C. Then 4mL of the newly prepared precursor solution was quickly added to it. Reflux was started and stirred continuously. After reacting for 20min, the reaction stock solution was dried by rotary evaporation to obtain green-emitting CdTe QDs, which were stored in deionized water.

[0021] (2) Take 50 μL of CdTe QDs and 10 μL of 9-fluorenone tetrahydrofuran solution (2 mM) and incubate at 60°C for 2 h, then add 400 μL of 3.6 mM sodium dodecyl sulfate aqueous solution to the above solution, and finally add 50 μL of 9-fluorenone tetrahydrofuran solution (2 mM) to react for 7 h, and centrifuge to purify to obtain small-sized organic nanocrystals.

[0022] Beneficial effects of the present invention:

[0023] (1) This method is simple, universal and has high yield.

[0024] (2) The organic nanocrystals produced by this method have a size of 30 nm and are very uniform. Such a small and uniform size can enable organic nanocrystals to be further applied in the fields of biomedicine, flexible electronics and high-energy materials.

[0025] (3) The synergistic effect between organic nanocrystals and quantum dots is particularly suitable for applications in sensing, fluorescence imaging, and biomarkers.

[0026] (4) Using CdTe quantum dots to prepare organic molecular crystals can successfully obtain small-sized and uniform organic nanocrystals, but replacing them with other quantum dots has not been successful.

[0027] (5) When the surfactant is sodium dodecyl sulfate, small-sized and uniform organic nanocrystals can be obtained, but replacing it with other surfactants failed. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the accompanying drawings.

[0029] Figure 1 This is the TEM image and fluorescence spectrum of CdTe quantum dots

[0030] Figure 2 This is the TEM image of Example 1

[0031] Figure 3 This is the TEM image of Example 2

[0032] Figure 4 This is the TEM image of Example 3

[0033] Figure 5 TEM image of comparative example 1

[0034] Figure 6 This is the TEM image of Comparative Example 2

[0035] Figure 7 TEM image of comparative example 3

[0036] Figure 8 TEM image of Comparative Example 4

[0037] Fig. 9 This is the TEM image of Comparative Example 5 DETAILED DESCRIPTION

[0038] Example 1

[0039] (1) Preparation method of CdTe quantum dots. 0.255g of tellurium powder and 0.0600g of sodium borohydride were put into a flask containing 10mL of H2O and reacted in a constant temperature water bath at 55°C. N2 was continuously introduced and stirred vigorously during the reaction process. The reaction was completed when the solution changed from black to dark purple. Then, the precursor was prepared. 0.0913g of cadmium chloride was weighed and put into a beaker. 66.5μL of thioglycolic acid and 50mL of deionized water were added. The solution was stirred with a glass rod from clear to white turbid. 2mol / L sodium hydroxide solution was added to adjust the pH of the solution to 9-10 (pH=7, the solution began to change from white turbidity to clear). After N2 was introduced into the dark purple solution for 30min, it was quickly heated to 100°C. Then 4mL of the newly prepared precursor solution was quickly added to it. Reflux was started and stirred continuously. After reacting for 20min, the reaction stock solution was dried by rotary evaporation to obtain green-emitting CdTe QDs, which were stored in deionized water.

[0040] (2) 50 μL of CdTe QDs and 10 μL of 9-fluorenone tetrahydrofuran solution (2 mM) were incubated at 60 °C for 2 h, followed by adding 400 μL of 3.6 mM sodium dodecyl sulfate aqueous solution to the above solution, and finally adding 50 μL of 9-fluorenone tetrahydrofuran solution (2 mM) to react for 7 h, and centrifugation was performed to purify. Figure 2 It can be seen that the size of 9-fluorenone nanocrystals is 30 nm and very uniform.

[0041] Example 2

[0042] Compared with Example 1, the difference is that the organic molecule in step 2) of Example 1 is 1,1,2,3,4,5-hexaphenylthiole, Figure 3 It can be seen that the size of 1,1,2,3,4,5-hexaphenylsilole nanocrystals is 30 nm and very uniform.

[0043] Example 3

[0044] Compared with Example 1, the difference is that the organic molecule in step 2) of Example 1 is trans, trans-1,4-diphenylene. Figure 4 It can be seen that the size of trans, trans-1,4-phenylene nanocrystals is 30 nm and is very uniform.

[0045] Comparative Example 1

[0046] Compared with Example 1, the difference is that there are no CdTe quantum dots and small-sized organic nanocrystals cannot be synthesized.

[0047] Comparative Example 2

[0048] Compared with Example 2, the difference is that there are no CdTe quantum dots and small-sized organic nanocrystals cannot be synthesized.

[0049] Comparative Example 3

[0050] Compared with Example 3, the difference is that there are no CdTe quantum dots and small-sized organic nanocrystals cannot be synthesized.

[0051] Comparative Example 4

[0052] Compared with Example 2, the difference is that CdSe quantum dots are used. Figure 8 It can be seen that small-sized organic nanocrystals cannot be synthesized.

[0053] Comparative Example 5

[0054] Compared with Example 2, the difference is that CdSe@ZnS quantum dots are used. Fig. 9 It can be seen that small-sized organic nanocrystals cannot be synthesized.

[0055] Comparative Example 6

[0056] Compared with Example 1, the difference is that when the surfactant used is polyvinyl pyrrolidone, small-sized organic nanocrystals cannot be synthesized.

[0057] The present invention is not limited to the specific technical solutions described in the above embodiments, and all technical solutions formed by equivalent replacement are within the protection scope required by the present invention.

Claims

1. A method for preparing small-sized organic nanocrystals, characterized in that: The preparation steps are as follows: Step (1): synthesizing CdTe quantum dots; Step (2): pre-incubating the CdTe quantum dots with organic molecules; the organic molecules are dissolved in tetrahydrofuran solvent, and the organic molecules are 9-fluorenone, 1,1,2,3,4,5-hexaphenylthiole or trans,trans-1,4-stilbene; Step (3): placing the solution obtained in step (2) into ultrapure water containing a poor solvent and a surfactant, wherein the surfactant is sodium dodecyl sulfate; Step (4): dissolving the organic molecules in step (2) in tetrahydrofuran, a good solvent, adding the solution to the solution containing functionalized quantum dots obtained in step (3), aging for 7-12 h, and centrifuging for purification to obtain small-sized organic nanocrystals.

2. The method for preparing small-sized organic nanocrystals according to claim 1, characterized in that: The preparation method of the quantum dots in step (1) is as follows: 0.255 g of tellurium powder and 0.0600 g of sodium borohydride are put into a flask containing 10 mL of H2O, and reacted in a constant temperature water bath at 55°C. The reaction process requires continuous introduction of N2 and vigorous stirring. The reaction is completed when the solution changes from black to dark purple. Then, a precursor is prepared by weighing 0.0913 g of cadmium chloride and putting it into a beaker. 66.5 μL of thioglycolic acid and 50 mL of deionized water are added. The solution is stirred with a glass rod from clear to white turbidity. 2 mol / L sodium hydroxide solution is added to adjust the pH of the solution to 9-10. At pH = 7, the solution begins to change from white turbidity to clear. The dark purple solution was passed through N2 for 30 min and then rapidly heated to 100°C. 4 mL of the newly prepared precursor solution was rapidly added thereto, and reflux was started with continuous stirring. After reacting for 20 min, the reaction stock solution was rotary evaporated to dryness to obtain CdTe QDs, which were stored in deionized water.

3. The method for preparing small-sized organic nanocrystals according to claim 1, characterized in that: The volume of quantum dots in step (2) is 50 μL; the organic molecule in step (2) is 9-fluorenone, which is dissolved in tetrahydrofuran at a concentration of 2 mM and a volume of 10 μL.

4. The method for preparing small-sized organic nanocrystals according to claim 1, characterized in that: The incubation time in step (2) is 2 h and the temperature is 60°C.

5. The method for preparing small-sized organic nanocrystals according to claim 1, characterized in that: The poor solvent in step (3) is ultrapure water with a volume of 400 μL. The surfactant contained in the ultrapure water is sodium dodecyl sulfate with a concentration of 3.6 mM.

6. The method for preparing small-sized organic nanocrystals according to claim 1, characterized in that: The centrifugation speed in step (4) is 12500 rpm, and the centrifugation is performed for 10 min.

7. Small-sized organic nanocrystals prepared according to any one of claims 1 to 6, characterized in that: The crystal size is 30nm and very uniform.

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