Water-phase long-afterglow silicon dioxide coated carbon dot compound and preparation method thereof

Abstract

The invention discloses a water-phase long-afterglow silicon dioxide-coated carbon dot compound and a preparation method thereof. The carbon dot compound is a compound formed by coating the periphery of a m-phenylenediamine polymer with silicon dioxide as a shell, more specifically, the carbon dot compound is soluble in water and can be stored in water for a long time. The afterglow life of a solution of the carbon dot compound under excitation of 365 nm is 864 ms, the solution of the carbon dot compound shows bright amaranth fluorescence under irradiation of a 365 nm ultraviolet lamp, and after the ultraviolet lamp is turned off, the solution of the carbon dot compound has purple afterglow which can be seen by naked eyes for 8 s.

Description

Technical Field

[0001] The invention belongs to the field of carbon dots, and in particular relates to an aqueous phase long afterglow silica-coated carbon dot composite and a preparation method thereof. Background Art

[0002] Carbon dots are a type of nano-quasi-spherical particles with a size less than 10 nm. They have attracted widespread attention due to their excellent optical properties, environmental friendliness, good biocompatibility, low toxicity, easy access to raw materials, and simple synthesis process.

[0003] Afterglow materials are photoluminescent materials, which can keep luminescence for a period of time after the external stimulus is removed. They have great potential in the fields of information encryption and bio-imaging. However, since the afterglow emission of current RTA-CDs materials is relatively single, mostly short-wavelength blue or green, RTA-CDs are less secure in the fields of anti-counterfeiting and information encryption. Moreover, long-wavelength afterglow materials have large penetration depth, long luminescence lifetime, and are not affected by background fluorescence, and have good application prospects in the field of bio-imaging. Therefore, the development of long-wavelength emission afterglow CDs is of great research value. Summary of the invention

[0004] The purpose of the present invention is to provide an aqueous long-afterglow silica-coated carbon dot composite and a preparation method thereof, so as to solve the problem that the existing carbon dot solution cannot emit long-wave afterglow in aqueous solution.

[0005] The present invention adopts the following technical solution: a carbon dot composite coated with silica having a long wavelength and a long afterglow in water phase. The carbon dot composite is a composite formed by silica as a shell wrapped around the periphery of a meta-phenylenediamine polymer.

[0006] Furthermore, the carbon dot composite is soluble in water and can be stored in water for a long time.

[0007] Furthermore, the afterglow lifetime of the solution of the carbon dot composite under 365 nm excitation is 864 ms.

[0008] Furthermore, the solution of the carbon dot complex exhibits bright purple-red fluorescence under 365 nm ultraviolet light, and has a purple afterglow visible to the naked eye for 8 seconds after the ultraviolet light is turned off.

[0009] A method for preparing a long-wavelength aqueous phase long afterglow silicon dioxide-coated carbon dot composite comprises:

[0010] Step 1: dissolving m-phenylenediamine and silicic acid in a reaction solvent, and placing the mixture in a reaction vessel for reaction to obtain a solution containing a first product;

[0011] Step 2: dialyzing the solution containing the first product in a dialysis bag;

[0012] Step 3: Add rhodamine B solution, silicic acid and ammonia water to the solution containing the first product after dialysis, and obtain a carbon dot complex coated with long-wavelength aqueous long-afterglow silica after ultrasound.

[0013] Furthermore, the reaction solvent in step 1 is water, ethanol, ether, benzene, THF or CCl4.

[0014] Furthermore, the reaction temperature of the reactor in step 1 is 160-230°C.

[0015] Furthermore, the reaction time of the reactor in step 1 is 8 to 14 hours.

[0016] Furthermore, the molecular weight cut-off of the dialysis bag in step 2 is 500 to 5000 Da, and the dialysis time of the dialysis bag in step 2 is 12 to 60 hours.

[0017] Furthermore, in step 3, the temperature during ultrasound is 25 to 55° C., and the ultrasound time is 2 to 6 hours. The beneficial effects of the present invention are:

[0018] The carbon dot composite prepared by the present invention produces afterglow emission peaks at about 450nm and 593nm when the excitation range is 300nm to 460nm;

[0019] The carbon dot composite prepared by the present invention has the characteristics of long emission wavelength, is non-toxic and harmless, has stable optical properties, can be stored for a long time, and is suitable for advanced information encryption fields and biological imaging;

[0020] The preparation method of the carbon dot composite of the present invention is simple to operate, has mild reaction conditions, is environmentally friendly, and has low cost;

[0021] The carbon dot composite prepared by the present invention has an afterglow lifetime of 864 ms under 365 nm excitation, and has a purple afterglow visible to the naked eye for 8 seconds after the ultraviolet lamp is turned off;

[0022] The carbon dot composite prepared by the present invention has a covalent network structure wrapping, so that the optical and physical properties of the carbon dot solution are stable and can be stored for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 These are photos of the aqueous afterglow carbon dot solution of Example 1 under 365nm ultraviolet light irradiation and under off conditions;

[0024] Figure 2 The X-ray diffraction (XRD) pattern of the aqueous afterglow carbon dot solution of Example 1;

[0025] Figure 3This is a Raman photo of the aqueous afterglow carbon dot solution of Example 1;

[0026] Figure 4 This is an infrared (FT-IR) photograph of the aqueous afterglow carbon dot solution of Example 1;

[0027] Figure 5 The fluorescence emission diagram of the aqueous afterglow carbon dot solution under different excitations of Example 1;

[0028] Figure 6 The afterglow emission graphs of the aqueous afterglow carbon dot solution of Example 1 under different excitations;

[0029] Figure 7 This is the afterglow lifetime diagram of the aqueous afterglow carbon dot solution of Example 1 under 365nm excitation;

[0030] Figure 8 This is a graph showing the change in afterglow intensity of the aqueous afterglow carbon dot solution of Example 1 under irradiation with a 365nm ultraviolet lamp for 4 hours;

[0031] Fig. 9 This is an application example diagram of the aqueous afterglow carbon dot solution of Example 1. DETAILED DESCRIPTION

[0032] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] The invention discloses a carbon dot composite coated with silica having a long wavelength and a long afterglow in water phase. The carbon dot composite is a composite formed by silica as a shell wrapped around the periphery of a meta-phenylenediamine polymer.

[0034] More specifically, the carbon dot complex is soluble in water and can be stored in water for a long time. The afterglow lifetime of the carbon dot complex solution under 365nm excitation is 864ms. The carbon dot complex solution exhibits bright purple-red fluorescence under 365nm ultraviolet light, and has a purple afterglow visible to the naked eye for 8s after the ultraviolet light is turned off.

[0035] The present invention also discloses a method for preparing a carbon dot composite coated with silica having a long wavelength and an aqueous phase with a long afterglow, comprising:

[0036] Step 1: dissolving m-phenylenediamine and silicic acid in a reaction solvent, and placing the mixture in a reaction vessel for reaction to obtain a solution containing a first product;

[0037] Step 2: dialyzing the solution containing the first product in a dialysis bag;

[0038] Step 3: Add rhodamine B solution, silicic acid and ammonia water to the solution containing the first product after dialysis, and obtain a carbon dot complex coated with long-wavelength aqueous long-afterglow silica after ultrasound.

[0039] Wherein, the reaction solvent in step 1 is water, ethanol, ether, benzene, THF or CCl4. The reaction temperature of the reactor is 160-230°C. The reaction time of the reactor is 8-14h. In step 3, the volume ratio of the rhodamine B solution, the dialyzed solution containing the first product, the silicic acid solution and the ammonia water is 1:10-40:2-6:1-3.

[0040] Wherein, the molecular weight cut-off of the dialysis bag in step 2 is 500 to 5000 Da, and the dialysis time of the dialysis bag in step 2 is 12 to 60 hours.

[0041] Wherein, the temperature during ultrasonication in step 3 is 25 to 55° C., and the ultrasonication time is 2 to 6 hours.

[0042] Example 1

[0043] Step 1: Dissolve 0.05 g of m-phenylenediamine and 5 mL of silicic acid in 10 mL of ethanol, stir thoroughly and place in a reaction kettle, and react at 180° C. for 8 h to obtain a solution containing the first product.

[0044] Step 2: The solution containing the first product is fully dialyzed in a dialysis bag; wherein the molecular weight cut-off of the dialysis bag is 2000Da, and the dialysis time in the dialysis bag is 48 hours.

[0045] Step 3: Add 3 mL of 2.0 mg / mL rhodamine B solution, 2 mL of silicic acid and 1 mL of ammonia water to 8 mL of the dialyzed solution containing the first product, and obtain a carbon dot complex after ultrasonic treatment, wherein the ultrasonic temperature is 30°C and the time is 5 hours.

[0046] Example 2

[0047] Step 1: Dissolve 0.1 g of m-phenylenediamine and 3 mL of silicic acid in 25 mL of ethanol, stir thoroughly and place in a reaction kettle, and react at 160° C. for 8 h to obtain a solution containing the first product.

[0048] Step 2: The solution containing the first product is fully dialyzed in a dialysis bag; wherein the molecular weight cut-off of the dialysis bag is 3000Da, and the dialysis time in the dialysis bag is 48 hours.

[0049] Step 3: Add 3 mL of 2.8 mg / mL rhodamine B solution, 4 mL of silicic acid and 1 mL of ammonia water to 10 mL of the dialyzed solution containing the first product, and obtain an aqueous phase long afterglow carbon dot@silica complex after ultrasonication, wherein the ultrasonic temperature is 25°C and the time is 6 hours.

[0050] Example 3

[0051] Step 1: Dissolve 0.2 g of m-phenylenediamine and 6 mL of silicic acid in 30 mL of ethanol, stir thoroughly and place in a reaction kettle, and react at 230° C. for 12 h to obtain a solution containing the first product.

[0052] Step 2: The solution containing the first product is fully dialyzed in a dialysis bag; wherein the molecular weight cut-off of the dialysis bag is 500Da, and the dialysis time in the dialysis bag is 12 hours.

[0053] Step 3: Add 4.5 mL of 0.8 mg / mL rhodamine B solution, 10 mL of silicic acid and 3 mL of ammonia water to 20 mL of the dialyzed solution containing the first product, and obtain an aqueous phase long afterglow carbon dot@silica complex after ultrasonication, wherein the ultrasonic temperature is 40°C and the time is 2 hours.

[0054] Example 4

[0055] Step 1: Dissolve 0.2 g of m-phenylenediamine and 8 mL of silicic acid in 40 mL of ethanol, stir thoroughly and place in a reaction kettle, and react at 180° C. for 8 h to obtain a solution containing the first product.

[0056] Step 2: The solution containing the first product is fully dialyzed in a dialysis bag; wherein the molecular weight cut-off of the dialysis bag is 5000Da, and the dialysis time in the dialysis bag is 48 hours.

[0057] Step 3: Add 2.0 mL of 3.2 mg / mL rhodamine B solution, 8 mL of silicic acid and 4 mL of ammonia water to 20 mL of the dialyzed solution containing the first product, and obtain an aqueous phase long afterglow carbon dot@silica complex after ultrasonication, wherein the ultrasonic temperature is 30°C and the time is 3 hours.

[0058] Example 5

[0059] Step 1: Dissolve 0.25 g of m-phenylenediamine and 10 mL of silicic acid in 45 mL of ethanol, stir thoroughly and place in a reaction kettle, and react at 220° C. for 14 h to obtain a solution containing the first product.

[0060] Step 2: The solution containing the first product is fully dialyzed in a dialysis bag; wherein the molecular weight cut-off of the dialysis bag is 5000Da, and the dialysis time in the dialysis bag is 60 hours.

[0061] Step 3: Add 4.5 mL of 4.2 mg / mL rhodamine B solution, 25 mL of silicic acid and 5 mL of ammonia water to 40 mL of the dialyzed solution containing the first product, and obtain an aqueous long afterglow carbon dot@silica complex after ultrasonication, wherein the ultrasonic temperature is 55°C and the time is 6 hours.

[0062] like Figure 1 As shown, the aqueous afterglow carbon dot solution prepared in Example 1 exhibits bright purple-red fluorescence under 365nm ultraviolet light, and still produces purple afterglow for a period of time after the ultraviolet light is turned off, which is visible to the naked eye for about 8 seconds.

[0063] like Figure 2 As shown, the aqueous afterglow carbon dot solution prepared in Example 1 produces a characteristic diffraction peak at 22.64°, which proves that the product maintains amorphous properties. This indicates that the product is incompletely carbonized to form amorphous carbon, that is, carbon dots.

[0064] like Figure 3 As shown, the aqueous afterglow carbon dot solution prepared in Example 1 has a peak at 1342.04 cm -1 The D peak is shown at 1591.15cm -1 Shows G peak, I G / I D =0.994, which proves the amorphous nature of the product. This also shows that the product is incompletely carbonized to form amorphous carbon, that is, carbon dots.

[0065] like Figure 4 As shown, the aqueous afterglow carbon dot solution prepared in Example 1 has a wavelength of 3200-3600 cm -1 The broad band at 1630 cm is attributed to the stretching vibrations of the OH and NH bonds. -1 The peak at 1090cm is attributed to the stretching vibration of CN. -1 and 779cm -1 The peaks are due to the stretching vibrations of Si-O-Si and Si-OC, which confirms the successful introduction of Si-O covalent bonds, which plays a key role in the long-wavelength afterglow emission of the product in aqueous solution.

[0066] like Figure 5 As shown, the aqueous afterglow carbon dot solution prepared in Example 1 produces fluorescence emission peaks at 465 nm and 588 nm, confirming that the product has long-wavelength fluorescence emission.

[0067] like Figure 6 As shown, the aqueous afterglow carbon dot solution prepared in Example 1 produces phosphorescence emission peaks at 465 nm and 593 nm, confirming that the product has long-wavelength afterglow emission.

[0068] like Figure 7 As shown, the afterglow lifetime of the aqueous afterglow carbon dot solution prepared in Example 1 under 365nm excitation is 864ms, which shows that the aqueous afterglow carbon dot solution prepared in Example 1 has an ultra-long afterglow lifetime.

[0069] like Figure 8 As shown, the afterglow intensity change of the aqueous afterglow carbon dot solution prepared in Example 1 under 365nm ultraviolet lamp irradiation for 4h, the afterglow intensity at 465nm and 593nm did not change significantly, which shows that the aqueous afterglow carbon dot solution prepared in Example 1 has excellent photostability.

[0070] like Fig. 9 As shown, the aqueous afterglow carbon dot solution prepared in Example 1 is used for pattern encryption, and presents a complete rose shape under ultraviolet irradiation. After the external excitation is turned off, only four petals can produce continuous light emission, which plays an encryption role.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A carbon dot composite coated with silica having a long wavelength aqueous phase long afterglow, characterized in that: The carbon dot composite is a composite formed by silicon dioxide as a shell wrapped around the periphery of the meta-phenylenediamine polymer.

2. The carbon dot composite coated with silica having a long wavelength and an aqueous phase long afterglow according to claim 1, characterized in that: The carbon dot composite is soluble in water and can be stored in water for a long time.

3. The carbon dot composite coated with silica having a long wavelength and an aqueous phase long afterglow according to claim 1, characterized in that: The afterglow lifetime of the carbon dot composite solution under 365 nm excitation is 864 ms.

4. The carbon dot composite coated with silica having a long wavelength and an aqueous phase long afterglow according to claim 1, characterized in that: The solution of the carbon dot complex exhibits bright purple-red fluorescence under 365 nm ultraviolet light, and has a purple afterglow visible to the naked eye for 8 seconds after the ultraviolet light is turned off.

5. A method for preparing a long-wavelength aqueous phase long-lasting silica-coated carbon dot composite, characterized in that: include: Step 1: dissolving m-phenylenediamine and silicic acid in a reaction solvent, and placing the mixture in a reaction vessel for reaction to obtain a solution containing a first product; Step 2: dialyzing the solution containing the first product in a dialysis bag; Step 3: Add rhodamine B solution, silicic acid and ammonia water to the solution containing the first product after dialysis, and obtain a carbon dot complex coated with long-wavelength aqueous long-afterglow silica after ultrasound.

6. The method for preparing a long-wavelength aqueous phase long afterglow silica-coated carbon dot composite according to claim 5, characterized in that: The reaction solvent in step 1 is water, ethanol, ether, benzene, THF or CCl4.

7. The method for preparing a long-wavelength aqueous phase long afterglow silica-coated carbon dot composite according to claim 5, characterized in that: The reaction temperature of the reactor in step 1 is 160-230°C.

8. The method for preparing a long-wavelength aqueous phase long afterglow silica-coated carbon dot composite according to claim 5, characterized in that: The reaction time of the reactor in step 1 is 8 to 14 hours.

9. The method for preparing a long-wavelength aqueous phase long afterglow silica-coated carbon dot composite according to claim 5, characterized in that: The molecular weight cut-off of the dialysis bag in step 2 is 500 to 5000 Da, and the dialysis time of the dialysis bag in step 2 is 12 to 60 hours.

10. The method for preparing a long-wavelength aqueous phase long afterglow silica-coated carbon dot composite according to claim 5, characterized in that: The temperature during ultrasonication in step 3 is 25 to 55° C., and the time of ultrasonication is 2 to 6 hours.

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