CN112175611B - Application of free radical initiator in adjusting and controlling maximum emission wavelength of carbon point fluorescence - Google Patents

Abstract

The invention researches the application of different free radical initiators in the regulation of the maximum emission wavelength of the carbon point fluorescence. Different from the traditional method that the fluorescence color of the carbon dots is regulated and controlled by using the polarity of different solvents, the carbon dot solution with different fluorescence colors can be obtained under the appropriate initiation condition by selecting different free radical initiators and controlling the dosage of the initiators. The method regulates and controls the fluorescence color of the known red fluorescent carbon dots on the basis of preparing the known red fluorescent carbon dots, and realizes the process that the carbon dots turn green from red to orange to yellow. The method has the characteristics of simple operation steps, rapidness, high efficiency, mild reaction conditions, stable carbon dot optical properties and the like.

Description

Application of Free Radical Initiator in Controlling the Maximum Emission Wavelength of Carbon Dot Fluorescence

technical field

The invention belongs to the technical field of carbon dot light emission, and specifically relates to the application of a free radical initiator in regulating the maximum emission wavelength of carbon dot fluorescence.

Background technique

Since the discovery of fluorescent carbon quantum dots in 2004, due to their good water solubility, biocompatibility, and low biological toxicity, they can be used as good electron acceptors and unique optical properties, and they are widely used in ion detection, bioimaging, catalysis, and photoelectric conversion. and other fields have great application prospects. There are many explanations for the mechanism of the optical properties of carbon quantum dots. Many research works demonstrate the laws and methods of the optical properties of carbon quantum dots by observing the particle size, surface state and heteroatom doping of carbon quantum dots. Among them, the reaction solvent and precursor are important factors to determine the optical properties of carbon quantum dots, and the emission wavelength of carbon quantum dots can be adjusted by changing the solvent and precursor. In the present invention, different kinds of free radical initiators are added to the prepared red fluorescent carbon quantum dot solution, and different kinds of free radicals are induced by heating or ultraviolet radiation to regulate the maximum emission wavelength of fluorescence.

Contents of the invention

The purpose of the present invention is to control the fluorescent color of a carbon dot through an initiator, and realize the regulation of multiple fluorescent colors by controlling the type of the initiator, the way of triggering and the amount of the initiator added.

In order to achieve the purpose of the present invention, on the basis of the prepared red carbon dot solution (hereinafter abbreviated as p-CDs), the technical scheme of the present invention includes the following steps: 1. By adding azobisisobutyronitrile (AIBN) Regulate the fluorescent color of red carbon dots; 2. Regulate the fluorescent color of red carbon dots by adding 2.2,2-azobis(2-methylpropylimidium) dihydrochloride (V-50); 3 .The fluorescent color of red carbon dots is regulated by adding other water-soluble initiators.

The application of free radical initiators in regulating the maximum emission wavelength of carbon dot fluorescence. On the basis of preparing the known red fluorescent carbon dot solution, the present invention regulates its fluorescence by adding different initiators. The steps are as follows:

1) Fluorescence color regulation of red carbon dots by azobisisobutyronitrile (AIBN)

Add 50-60 μL of red carbon dot solution with a concentration of 4 mg/mL to 6 mL of ethanol solution, then add 0-90 mg of azobisisobutyronitrile (AIBN) initiator to it, and place in an oven at 60-70 °C React in 12-24 h to obtain carbon dot solutions with different fluorescent colors.

2) Fluorescence color regulation of red carbon dots by 2,2-azobis(2-methylpropylimidium) dihydrochloride (V-50)

Add 50-60 μL of red carbon dot solution with a concentration of 4 mg/mL to 5 mL of aqueous solution, then add 0-50 mg of V-50 initiator to it, and react in an oven at 60-70 °C for 12 h or at 395 After irradiating for 3-12 h under a nm ultraviolet lamp, carbon dot solutions with different fluorescent colors were obtained.

3) Other initiators regulate the fluorescence color of red carbon dots

Add 60 μL of red carbon dot solution with a concentration of 4 mg/mL to 6 mL of aqueous solution, then add 0-10 mg of other types of initiators to it, and react in an oven at 60-70 °C for 0-12 h to obtain a fluorescent color Various carbon dot solutions.

The mass fraction of the red carbon dot solution described in the step is 4 mg/mL.

Azobisisobutyronitrile (AIBN) is an oil-soluble initiator with a half-life temperature of 65 °C for 10 h.

2,2-Azobis(2-methylpropylimidium) dihydrochloride (V-50) is a water-soluble photoinitiator with a 10 h half-life temperature of 56 °C.

Other classes of initiators include alpha-ketoglutarate, ammonium persulfate, and potassium persulfate, all of which are water-soluble. In addition to the initiators listed in the examples, other free radical initiators will also be included, such as: organic peroxide initiators such as cyclohexanone peroxide, dibenzoyl peroxide, tert-butyl hydroperoxide; Azo initiators such as isoheptanonitrile.

Azos and α-ketoglutaric acid are used as regulators, and heating or ultraviolet radiation is used as the triggering method.

Specifically:

1: Fluorescence color regulation of red carbon dots by azobisisobutyronitrile (AIBN)

Add 50-60 μL of red carbon dot solution with a concentration of 4 mg/mL to 6 mL of ethanol solution, then add 0-90 mg of azobisisobutyronitrile (AIBN) initiator to it, and place in an oven at 60-70 °C React in 12-24 h to obtain carbon dot solutions with different fluorescent colors.

2: Fluorescence color regulation of red carbon dots by 2,2-azobis(2-methylpropylimidium) dihydrochloride (V-50)

Add 50-60 μL of red carbon dot solution with a concentration of 4 mg/mL to 5 mL of aqueous solution, then add 0-50 mg of V-50 initiator to it, and react in an oven at 60-70 °C for 12 h or at 395 After irradiating for 3-12 h under a nm ultraviolet lamp, carbon dot solutions with different fluorescent colors were obtained.

3: Fluorescent color regulation of red carbon dots by other initiators

Add 60 μL of red carbon dot solution with a concentration of 4 mg/mL to 6 mL of aqueous solution, then add 0-10 mg of other types of initiators to it, and react in an oven at 60-70 °C for 0-12 h to obtain a fluorescent color Various carbon dot solutions.

The method of using an initiator to regulate the fluorescent color of carbon dots described in the present invention has certain guiding significance for the explanation of the fluorescence transition mechanism.

Description of drawings

Figure 1 is the UV and fluorescence spectra of carbon dots before and after AIBN treatment, in the figure: a) UV absorption spectrum of p-CDs in ethanol solution; b) fluorescence emission spectrum of p-CDs at an excitation wavelength of 420 nm Figure; c) Add 10 mg of azobisisobutyronitrile (AIBN), the carbon dot solution is orange fluorescence UV absorption spectrum; d) Add 10 mg of azobisisobutyronitrile (AIBN), when the excitation wavelength is 420 nm The fluorescence emission spectrum of the following; e) Add 20 mg of azobisisobutyronitrile (AIBN), the carbon dot solution is yellow fluorescence UV absorption spectrum; f) Add 20 mg of azobisisobutyronitrile (AIBN), Fluorescence emission spectrum at an excitation wavelength of 420 nm; g) Adding 40 mg of azobisisobutyronitrile (AIBN), the carbon dot solution is green fluorescent UV absorption spectrum; h) Adding 40 mg of azobisisobutyronitrile (AIBN) Butyronitrile (AIBN), the fluorescence emission spectrum at the excitation wavelength of 420 nm.

Figure 2 is the UV and fluorescence spectra of carbon dots before and after V-50 treatment, in the figure: a) UV absorption spectra of p-CDs in deionized aqueous solution; b) p-CDs at an excitation wavelength of 420 nm Fluorescence emission spectrum; c) Adding 30 mg of 2,2-azobis(2-methylpropylimidium) dihydrochloride (V-50), the carbon dot solution is yellow fluorescent UV absorption spectrum; d ) with 30 mg of 2,2-azobis(2-methylpropylimidium) dihydrochloride (V-50), the fluorescence emission spectrum at an excitation wavelength of 420 nm; e) with 50 mg 2,2-Azobis(2-methylpropyl imidium) dihydrochloride (V-50), the carbon dot solution is the ultraviolet absorption spectrum of yellow fluorescence; f) adding 50 mg of 2,2- Fluorescence emission spectrum of nitrogen bis(2-methylpropylimidium) dihydrochloride (V-50) at an excitation wavelength of 420 nm.

Figure 3 is the UV and fluorescence spectra of carbon dots before and after treatment with α-ketoglutaric acid. In the figure: a) UV absorption spectra of p-CDs in deionized aqueous solution; b) p-CDs at an excitation wavelength of 420 nm The fluorescence emission spectrum of the following; c) Add 2 mg of α-ketoglutarate, the carbon dot solution is green fluorescent UV absorption spectrum; d) Add 2 mg of α-ketoglutarate, the excitation wavelength is 420 Fluorescence emission spectrum at nm; e) Add 10 mg of α-ketoglutarate, the carbon dot solution is green fluorescent UV absorption spectrum; f) Add 10 mg of α-ketoglutarate, at the excitation wavelength A graph of the fluorescence emission spectrum at 420 nm.

Detailed ways

The present invention will be further described below in conjunction with the examples, rather than limiting the present invention.

The present invention first utilizes known method to prepare red fluorescent carbon dot solution and specific steps are: weigh 0.6 g of p-phenylenediamine, put into 60mL of ethanol, pour the mixed solution into polytetrafluoroethylene for reaction About 2/3 of the kettle, after tightening, put it in an oven and heat it to 180°C, and react for 12 hours. After cooling to room temperature, the burned carbon dots were separated and purified in a chromatographic column with dichloromethane and absolute ethanol to obtain a red carbon dot solution (p-CDs) and refrigerated for later use.

Example 1

Add 6 mL of absolute ethanol to eleven 20 mL sample bottles, 60 μL of red carbon dot solution with a mass fraction of 4 mg/mL, add 0 mg, 6 mg, 10 mg, 20 mg, 30 mg, 40 mg , 50 mg, 60 mg, 70 mg, 80 mg, and 90 mg azobisisobutyronitrile (AIBN). The oven was heated to 70 °C and reacted for 12 h. The reacted solution was irradiated under a 395 nm ultraviolet lamp, and it was found that the fluorescence showed red, orange-red and yellow-green changes.

Example 2

Add 6 mL of absolute ethanol to six 20 mL sample bottles, 60 μL of red carbon dot solution with a mass fraction of 4 mg/mL, add azobisisobutyronitrile (AIBN) 0 mg, 5 mg, 10 mg, 20 mg, 30 mg, 40 mg. The oven was heated to 70 °C and reacted for 24 h. The reacted solution was irradiated under a 395 nm ultraviolet lamp, and it was found that the fluorescence showed red, orange-red and yellow and yellow-green and green changes. Their fluorescence spectra are shown in Figure 1.

In Figure 1, in the UV absorption spectrum from a) to g), after increasing the amount of free radicals added, the peak at 200-350 nm has changed significantly. From b) to h) in the fluorescence spectrum, the maximum absorption wavelength begins to gradually shift to shorter wavelengths, which indicates that the structure of the original carbon dots begins to change with the increase of the amount of azobisisobutyronitrile added.

Example 3

Add 6 mL of deionized water to each of the eight 5 mL sample bottles, 60 μL of the red carbon dot solution with a mass fraction of 4 mg/mL, and add 2,2-azobis(2-methylpropylimidium) di-salt in sequence Salt (V-50) 0 mg, 2 mg, 6 mg, 10 mg, 20 mg, 30 mg, 40 mg, 50 mg. Under the irradiation of UV light at 395 nm, react for 12 h. The carbon dot aqueous solution without V-50 is easy to agglomerate, and the carbon dot solution with V-50 is well dispersed, and with the increase of the initiator dose, the maximum emission wavelength of the fluorescence becomes yellow. Its UV and fluorescence emission spectra are shown in Fig. 2 .

In the ultraviolet absorption spectrum from a) to e) in Figure 2, after increasing the amount of free radicals added, the peak at 200-350 nm has changed. The fluorescence spectrum from b) to f) shows that the maximum absorption wavelength directly shifts to the short wavelength, and in the process of moving to the short wavelength, the water solubility of the carbon dots is improved.

Example 4

Add 6 mL of deionized water to six 10 mL sample bottles, 60 μL of red carbon dot solution with a mass fraction of 4 mg/mL, add α-ketoglutarate 0 mg, 2 mg, 4 mg, 6 mg, 8 mg, 10 mg. Heat the oven to 60 °C and react for 0-12 h. The fluorescence spectrum is shown in Figure 3.

In the ultraviolet absorption spectrum from a) to e) in Figure 3, after adding free radicals, the peak at 200-300 nm changed immediately. From b) to f) in the fluorescence spectrum, the maximum absorption wavelength shifts directly to the short wavelength.

The experimental proportions and reaction conditions of the above examples can be properly adjusted according to the properties of the free radical initiator. The amount of the free radical initiator is not limited, and the experiment can also be carried out by adjusting the temperature or photoinitiation. The free radical initiator used can also be other organic peroxide initiators, azo initiators. Although the present invention has been described in conjunction with the preferred embodiments, the present invention is not limited to the above-described embodiments.

Claims (1)

1. The application of free radical initiators in regulating the maximum emission wavelength of carbon dot fluorescence is characterized in that, as the amount of free radical initiator increases, the displacement of the maximum emission wavelength of fluorescence of carbon dots to the short wavelength direction increases, Including the following steps: Add 50-60 μL of red carbon dot solution with a concentration of 4 mg/mL to 6 mL of ethanol, then add no more than 90 mg of azobisisobutyronitrile, and react in an oven at 60-70 °C for 12-24 hours to obtain Modified carbon dots whose fluorescence maximum emission wavelength shifts to the short wavelength direction; The regulated carbon dots are red carbon dots.

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