KR102127699B1 - Fluorescent sensor for detecting aromatic nitro compounds - Google Patents

Abstract

The present invention relates to a carbon nano dot for detecting an aromatic nitro compound and a method for manufacturing the same, since the carbon nano dot is produced through a hydrothermal reaction of a mixed solution containing pyromellitic acid and an alkylenediamine compound. Not only is this simple and economical, the quantum yield is excellent, and the detection ability for the aromatic nitro compound is remarkably excellent, and thus it can be usefully used in various fields requiring the detection of the aromatic nitro compound.

Description

Carbon nanopoint for detecting aromatic nitro compounds{Fluorescent sensor for detecting aromatic nitro compounds}

The present invention relates to a carbon nano dot for detecting an aromatic nitro compound and a method for manufacturing the same.

Analysis of aromatic nitro compounds such as nitrobenzene, nitrotoluene and nitrophenols in natural and effluent waters is of central interest due to numerous activities, while the compounds are not only human, but also animals, plants and Since it has serious toxicity to aquatic organisms, various aromatic nitro compounds are regulated. In particular, 4-nitrophenol (4-nitro phenol, 4-NP) is one of the dangerous substances because it has high toxicity, low degradability, and high solubility in most aquatic environments. The US Environmental Protection Agency (EPA) Is specified in Short-term acute inhalation or ingestion of 4-nitrophenol can lead to headache, drowsiness, nausea, and cyanosis, and has been reported to be a potential cause of carcinogens and malformation factors and mutations, making its application more tightly controlled. However, 4-nitrophenol is widely used as an intermediate chemical in many production processes, including pharmaceuticals, dyes, pesticides, pesticides, herbicides, leather fungicides and acid base indicators, and when used as a component of fertilizers or pesticides, crops, It is also identified as a dangerous food chain contaminant that may remain in vegetables, fruits and water resources.

Therefore, even if 4-nitrophenol is used, a system for easily detecting and treating 4-nitrophenol remaining in the environment is required to use and process more safely, and for this, a trace amount of 4-nitrophenol is simpler. A technique for sure detection is essential.

Conventionally, 4-nitrophenol was detected by a method such as a spectrophotometer, capillary region electrophoresis, electrochemical method and chemiluminescence. However, most of the above methods take a lot of time, complicated processes, and require expensive equipment or devices.

Therefore, for the detection of aromatic nitro compounds, the manufacturing and use process is simple, the detection capability is excellent, the reliability is high, and the detection efficiency is excellent and the development of an economical detection technique is required.

Republic of Korea Patent Publication No. 2007-0000408 Republic of Korea Patent Publication No. 2011-0085483

The object of the present invention is a simple manufacturing and use process for the detection of aromatic nitro compounds such as 4-nitrophenol, as well as high detection performance and high reliability, excellent detection efficiency, and an economical sensor and method for manufacturing the same. To provide.

In order to solve the above problem,

The present invention, in one embodiment, nitrogen is doped, and includes an amide group on the surface,

When measuring UV-vis absorbance, it has an absorption maximum at 410 nm to 430 nm in a wavelength range of 400 to 650 nm,

When measuring light luminescence (PL), carbon nanodots having a fluorescence emission maximum at 475 to 495 nm in a wavelength range of 400 to 740 nm are provided.

In addition, the present invention in one embodiment,

And performing a hydrothermal reaction of the mixed solution containing pyromellitic acid and an alkylenediamine compound to prepare carbon nanodots,

The carbon nano-dots are doped with nitrogen and provide a method for producing carbon nano-dots containing an amide group on the surface.

Furthermore, the present invention is in one embodiment,

Bonding the aromatic nano nitro compound to the surface of the carbon nano dot by contacting the aromatic nano compound with the carbon nano dot; And

It provides a method for detecting an aromatic nitro compound comprising the step of irradiating light to the carbon nano-dots to which the aromatic nitro compound is bound.

Since the carbon nano-dots according to the present invention are prepared through a hydrothermal reaction of a mixed solution containing pyromellitic acid and an alkylenediamine compound, the manufacturing method is simple and economical as well as excellent in quantum yield, and for aromatic nitro compounds. Since the detection ability is remarkably excellent, it can be usefully used in various fields that require the detection of aromatic nitro compounds.

1 is an image showing a mechanism for forming carbon nanodots according to the present invention.
2 is a schematic view showing a mechanism for detecting an aromatic nitro compound according to the present invention.
3 is a transmission electron microscope (TEM) analysis result of a carbon nano dot according to the present invention, (a) is a transmission electron microscope (TEM) image of the carbon nano dots, (b) is a transmission electron microscope (TEM) It is a histogram showing the particle size distribution of the observed carbon nanodots.
4 is a graph analyzing X-ray photoelectron spectroscopy (XPS) of carbon nanodots according to the present invention.
5 is a graph analyzing Fourier transform infrared spectroscopy (FT-IR) of carbon nanodots according to the present invention.
6 is a graph showing changes in light luminescence (PL) of carbon nanodots according to the present invention according to the wavelength of light to be irradiated.
7 is a graph showing changes in optical luminescence (PL) of carbon nanodots according to the present invention according to the type of detection compound.
Figure 8 is a graph showing the intensity of light luminescence (PL) of carbon nanodots according to the present invention for 4-nitrophenol, (a) is the result of the pH of the mixed solution, (b) is mixed It is the result according to the content (ion amount) of NaCl added to the solution.
9 is a graph showing changes in light luminescence (PL) of carbon nanodots according to the present invention according to the concentration of 4-nitrophenol present in a mixed solution.

The present invention can be applied to various changes and can have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description.

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In the present invention, terms such as "comprises" or "have" are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but one or more other features. It should be understood that the existence or addition possibilities of fields or numbers, steps, operations, components, parts or combinations thereof are not excluded in advance.

In addition, the accompanying drawings in the present invention should be understood to be shown enlarged or reduced for convenience of explanation.

In the present invention, "molar part" is a term indicating a molar ratio, and may indicate the same as "mol%" when indicating the molar ratio of component a to 100 mol of the total composition. For example, when the component a is contained in 10 to 20 mol parts with respect to 100 mol parts of the composition, the component a may be the same as that contained in 10 to 20 mol% in the composition.

The present invention relates to a carbon nano dot for detecting an aromatic nitro compound and a method for manufacturing the same.

Analysis of aromatic nitro compounds such as nitro benzene, nitro toluene and nitrophenols in natural and effluent waters is of central interest due to numerous activities, while the compounds are not only human, but also animals, plants and Since it has serious toxicity to aquatic organisms, various aromatic nitro compounds are regulated. In particular, 4-nitrophenol (4-NP) is highly toxic and has low degradability, so it exhibits high solubility in most aquatic environments. Headache, drowsiness, nausea, and cyanosis when acute inhalation or ingestion of 4-nitrophenol in a short period of time It can cause back. In addition, 4-nitrophenol is known as a potential carcinogen, and has been reported as a cause of malformation factor and mutation, so its application is more strictly controlled. However, aromatic nitro compounds such as 4-nitrophenol were detected by methods such as spectrophotometer, capillary region electrophoresis, electrochemical method and chemiluminescence. However, most of the above methods are time-consuming, complicated, and require expensive equipment or equipment.

Accordingly, the present invention provides a carbon nano dot for detecting an aromatic nitro compound and a method for manufacturing the same.

Since the carbon nano-dots according to the present invention are prepared through a hydrothermal reaction of a mixed solution containing pyromellitic acid and an alkylenediamine compound, the manufacturing method is simple and economical as well as excellent in quantum yield, and for aromatic nitro compounds. Since the detection ability is remarkably excellent, it can be usefully used in various fields that require the detection of aromatic nitro compounds.

Hereinafter, the present invention will be described in more detail.

Carbon nano dots

In one embodiment, the present invention provides carbon nanodots that are doped with nitrogen and include amide groups on the surface.

The carbon nanodots according to the present invention may be composed of one carbon nanoparticle or a plurality of carbon nanoparticles aggregated to form one nanodot, and may have an average particle size of 1.0 nm to 10.0 nm. More specifically, the carbon nano-dots are 1.0 nm to 8.0 nm, 1.0 nm to 6.5 nm, 1.0 nm to 5.0 nm, 2.0 nm to 10.0 nm, 2.5 nm to 10.0 nm, 4.0 nm to 10.0 nm, 2.0 nm to 8.0 nm , 2.0 nm to 7.0 nm, or 2.5 nm to 6.8 nm. In addition, the carbon nano-dots may have a monodispersity of 4.41±1.50 nm or 4.41±0.90 nm. According to the present invention, the fluorescence emission of the carbon nano-dots in the visible region can be realized with a high quantum yield of 70% or more by controlling the average particle size of the carbon nano-dots in the above range.

In addition, the carbon nano-dots are doped with nitrogen atoms (N), and an amide group (-C(O)NH ₂ ) is introduced to the surface, and nitrogen atoms (N) and oxygen atoms ( O) may be included in a certain ratio. Specifically, when analyzing components through X-ray photoelectron spectroscopy (XPS) targeting carbon nanodots according to the present invention, carbon atoms (C), oxygen atoms (O), and nitrogen atoms (N) are each 64±5 at% , 20±5 at% and 16±5 at%.

In addition, the carbon nano dot is doped with a nitrogen atom (N) therein, an amide group (-C(O)NH ₂ ) is introduced to the surface, and X-ray photoelectron spectroscopy (XPS) and/or Fourier transform infrared spectroscopy ( FT-IR) analysis may have a specific peak.

As an example, the carbon nano-dots are pyridyl (C-(NH)-C) and pyrrole (C-(NH)-C) bonds indicating that nitrogen (N) is doped during X-ray photoelectron spectroscopy (XPS) measurements. The amide (C(=O)NH-) binding peak indicating the introduction of an amide group to the peak and the surface can be represented at 399.0±0.5 eV and 400.7±0.5 eV.

As another example, the carbon nano-dots are measured by Fourier transform infrared spectroscopy (FT-IR), elongation vibration peak of NH bond at 3246±1.0 cm ⁻¹ ; Bending vibration peaks of C(=O)-NH ₂ bonds (amide bonds) at 1570±1.0 cm ⁻¹ and 1658±1.0 cm ⁻¹ respectively; Peak of CN binding at 1400±1.0 cm ⁻¹ ; And a shaking banding peak of the NH ₂ bond at 600-900 cm ⁻¹ .

The carbon nano dot of the present invention has a structure in which a nitrogen atom (N) is doped therein and an amide group (-C(O)NH ₂ ) is introduced into the surface as a functional group that reacts with an aromatic nitro compound, and thus a very small amount of aromatics The nitro compound also has an advantage of effectively detecting.

In addition, the carbon nano-dots according to the present invention are hydroxy (-OH), carboxyl (-COOH) and amino groups (-NR ₂ , -NHR, -NH ₂ ) with an amide group (-C(O)NH ₂ ) on the surface. Etc.) may be further included. Hydroxy (-OH) and/or carboxyl groups (-COOH) introduced on the surface of the carbon nano-dots are functional groups derived from pyromellitic acid, a carbon source used in the production of carbon nano-dots, to improve the hydrophilicity of the carbon nano-dots. can do.

Furthermore, the carbon nano dot according to the present invention has an absorption maximum at 410 nm to 430 nm in a wavelength range of 400 to 650 nm when measuring UV-vis absorbance,

When measuring light luminescence (PL), it may have a fluorescence emission maximum at 475 to 495 nm in a wavelength range of 400 to 740 nm.

More specifically, the carbon nano-dots are 410 nm to 425 nm, 410 nm to 420 nm, 410 nm to 417 nm, 413 nm to 430 nm, 413 nm to 425 in the 400 to 650 nm wavelength range when measuring UV-vis absorbance. It may have an absorption maximum in nm, 411 nm to 420 nm, or 412 nm to 418 nm. In addition, the carbon nano-dots fluorescence at 475 to 490 nm, 475 to 485 nm, 480 to 495 nm, 480 to 490 nm, or 482 to 486 nm in the wavelength range of 400 to 740 nm when measuring photoluminescence (PL) It has a maximum emission and can emit cyan light.

Conventionally, carbon nanodots known in the art are excited by ultraviolet (UV) light having a wavelength of 410 nm or less, specifically 400 nm or less, which induces side effects of low tissue penetration and high light damage, and emit blue light. It has characteristics. However, the carbon nano-dots of the present invention are doped with nitrogen (N) and are excitable in a visible light region of 410 nm or more, including an amide group on the surface, and emit blue-green light.

In addition, the carbon nano-dots may have a high quantum yield of 70% or more, specifically 70% to 85%, 70% to 80%, 72% to 78%, 74% to 84%, or 73% to 76 %.

In addition, the carbon nano-dots contain less than 5% or less than 2% of the total functional groups on the surface, or in some cases, do not contain it, so they are stable in a wide pH range and high ion concentration environment of 0.01M to 2M or more. Fluorescence emission is possible.

Manufacturing method of carbon nano dots

In addition, the present invention in one embodiment,

Comprising the step of performing a hydrothermal reaction of a mixed solution containing a pyromellitic acid and an alkylenediamine compound to prepare a carbon nano dot doped with nitrogen,

The carbon nano-dots are doped with nitrogen and provide a method for producing carbon nano-dots containing an amide group on the surface.

The method for producing carbon nanodots according to the present invention can be performed through a hydrothermal reaction of a mixed solution containing pyromellitic acid as a carbon source and an alkylenediamine compound as a nitrogen source, and the carbon nanodots prepared accordingly contain nitrogen. Doped and may include amide groups on the surface. Referring specifically to FIG. 1, pyromellitic acid includes four carboxyl groups centered on a benzene ring. When pyromellitic acid and an alkylenediamine compound having two amine groups are mixed and hydrothermal reaction is performed, alkylenediamine The amine group (-NH ₂ ) of the compound acts as a base catalyst in which the carboxyl group (-COOH) of pyromellitic acid is dehydrated, and can be dehydrogenated by being self-inserted into the graphene structure realized by pyromellitic acid. An amide group can be formed through an amide reaction with a carboxyl group of the acid. Subsequently, the graphene structure further undergoes an intramolecular dehydrogenation reaction to form heterocycles such as a pyridine ring, pyrrole ring, pyrrolidine ring, and piperidine ring, and at the same time through intermolecular interactions inside the carbon nanodots. Nitrogen (N) of an amino group or a pyridine group/pyrrole group is partially doped with carbon (C) of the graphene structure, and the graphene structure thus formed may be condensed as a core through an aromatization and/or carbonization process. .

At this time, the alkylenediamine compound may be mixed with pyromellitic acid in a specific content so as to form an appropriate amount of amide groups at the prepared carbon nanodots. Specifically, the alkylenediamine compound may be mixed in an amount of 100 to 1,000 mol parts with respect to 100 mol parts of pyromellitic acid, specifically 150 to 900 mol parts, 200 to 800 mol parts, and 150 to 600 mol parts with respect to 100 mol parts of pyromellitic acid , 200 to 500 moles, 200 to 300 moles, 150 to 450 moles, 300 to 1,000 moles, 500 to 1,000 moles, 700 to 1,000 moles, 250 to 800 moles, 300 to 600 moles, 300 to 500 moles 300 to 400 moles, or It may be mixed at 350 to 450 molar parts.

In addition, the mixture comprising the pyromellitic acid and the alkylenediamine compound may include distilled water, N-methylpyrrolidone (N-MP), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), etc. as a solvent. In addition, the temperature of the hydrothermal reaction can be carried out at a temperature above the boiling point of the solvent. As one example, the method for preparing carbon nanodots according to the present invention performs a hydrothermal reaction at a temperature of 100°C or higher, 150°C or higher, or 200±5°C after dissolving pyromellitic acid and an alkylenediamine compound in distilled water. can do.

In addition, the hydrothermal reaction may be performed for a time sufficient for the carboxyl group (-COOH) of pyromellitic acid and the amine group (-NH ₂ ) of the alkylenediamine compound to react. Specifically, the hydrothermal reaction may be performed for 1 hour to 10 hours, more specifically 1 hour to 8 hours, 1 hour to 6 hours, 1 hour to 4 hours, 2 hours to 10 hours, 4 hours to 10 hours Hours, 6 hours to 10 hours, 3 hours to 8 hours, 4 hours to 8 hours, or 5 hours to 7 hours.

The method for producing carbon nanodots according to the present invention uses a hydrothermal reaction of pyromellitic acid containing four or more carboxyl groups as a carbon source and an alkylenediamine compound as a nitrogen source, and nitrogen (N) is doped in a simple process and the amide group In addition, it is not only easy to manufacture the introduced carbon nanodots, it is also economical, and does not require a separate equipment such as an ultrasonic irradiator, and can use water as a solvent, thereby providing an environmentally friendly advantage.

Aromatic nitro compound detection method

In addition, the present invention in one embodiment,

Bonding the fluorescent sensor according to the present invention and an aromatic nitro compound to the surface; And

It provides a method for detecting an aromatic nitro compound comprising the step of irradiating light to a fluorescent sensor coupled to the aromatic nitro compound.

The method for detecting an aromatic nitro compound according to the present invention can rapidly detect an aromatic nitro compound present in a solution with high sensitivity and selectivity by using the above-described carbon nano-dots doped with nitrogen (N) and having an amide group on the surface. There is an advantage.

Specifically, as shown in FIG. 2, the carbon nanodots according to the present invention are two amide groups present on the surface when they are in contact with an aromatic nitro compound, for example 4-nitrophenol (4-NP) (- C(=O)-NH ₂ ) reacts with a hydroxy group of 4-nitrophenol to form a spiro cyclic Meisenheimer complex with a positive charge, where the negative charge of the nitro group is a cycle. It may be delocalized through the hexadiene ring, and through this, the positive charge may be distributed over the iminium group. The delocalization of the nitro group stabilizes the carbon nanodots through the spiro cyclic Meizenheimer complex, thereby improving the energy transfer process that induces fluorescence quenching of the carbon nanodots. That is, when the carbon nano-dots react with the aromatic nitro compound, since the fluorescence emission of the excited carbon nano-dots is suppressed by having a stable structure for easy energy transfer, it is possible to confirm the presence of the aromatic nitro compound.

Here, in order to detect the aromatic nitro compound, the detection method may irradiate light of a specific wavelength to the carbon nano-dots in the mixed solution, wherein the light of the specific wavelength may be light in a wavelength range of 380 to 450 nm. More specifically, the light irradiated to the carbon nano-dots in the mixed solution is 410 nm to 425 nm, 410 nm to 420 nm, 410 nm to 417 nm, 413 nm to 430 nm, 413 nm to 425 nm, 411 nm to 420 nm Or it may be light having a wavelength of 412 nm to 418 nm.

On the other hand, the carbon nano-dots may be mixed with the aromatic nitro compound at a concentration of 1 μM to 1 mM, specifically 1 μM to 800 μM, 1 μM to 600 μM, 1 μM to 500 μM, 1 μM to 300 μM, 1 μM to 100 μM, 100 μM to 1 mM, 200 μM to 1 mM, 400 μM to 1 mM, 600 μM to 1 mM, 800 μM to 1 mM, 10 μM to 500 μM, 10 μM to 250 μM, 10 μM to 100 μM, 10 μM to 80 μM, 10 μM to 60 μM, 10 μM to 50 μM or 10 μM to 30 μM.

Further, the aromatic nitro compound may be mixed in a solution state when mixed with carbon nanodots. As one example, the aromatic nitro compound may be dissolved in water.

In addition, the concentration of the aromatic nitro compound in the solution mixed with the carbon nano-dots is not particularly limited, but may be 15 nM or higher when the concentration of the carbon nano-dots is 20 μg/ml, specifically 20 nM or higher, 100 nM Or 15 nM to 200 μM. In general, an aromatic nitro compound, especially mono nitrophenol, has excellent solubility in water, and thus, when it is present in a small amount in water, its detection is difficult. However, in the method for detecting an aromatic nitro compound according to the present invention, the detection ability for the aromatic nitro compound is remarkably excellent, and thus, an aromatic nitro compound present in a very small amount in water by using the carbon nano dot of the present invention having a detection limit concentration of 17 nM It can also be easily detected.

Furthermore, the aromatic nitro compound may be included without particular limitation as long as it is a compound containing at least one nitro group in the aromatic ring and at least one hydroxyl group that will react with an amide group of a carbon nanodot. Specifically, the aromatic nitro compound may include, for example, 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, picric acid, and other compounds.

Hereinafter, the present invention will be described in more detail by examples and experimental examples.

However, the following examples and experimental examples are merely illustrative of the present invention, and the contents of the present invention are not limited to the following examples and experimental examples.

Examples 1 to 5.

Pyromelitic acid (1 mmol) and ethylenediamine were added to 5 ml of distilled water, and stirred until uniformly dissolved to a clear solution. At this time, the amount of the ethylenediamine was adjusted as shown in Table 1 below. Thereafter, the mixed solution was transferred to a stainless steel autoclave lined with Teflon, sealed, and then placed in a silicone muffle furnace and reacted at 200±2° C. for 6 hours. When the reaction was completed, the mixed solution (color: yellow-green) was cooled to room temperature, washed with ethanol, and centrifuged at 9,000 rpm for 15 minutes. The centrifuged solid was collected to obtain carbon nanodots.

The amount of ethylenediamine used Example 1 0.5 mmol Example 2 1.0 mmol Example 3 2.0 mmol Example 4 4.0 mmol Example 5 8.0 mmol

Comparative Example 1.

Carbon nanodots were obtained in the same manner as in Example 4, except that citric acid was used in Example 4 instead of pyromellitic acid.

Experimental Example 1.

The following experiments were performed to confirm the composition and structure of the carbon nanodots according to the present invention.

A) Transmission electron microscope (TEM) measurement

After dispersing the carbon nano-dots prepared in Example 4 in distilled water, a sample was prepared by trap casting, and a transmission electron microscope (TEM) was performed on the prepared sample. The results are shown in FIG. 3.

Referring to FIG. 3, it can be confirmed that the carbon nanodots prepared in Example 4 are spherical particles having an average particle size of 2.8 nm to 6.4 nm, and a monodispersity of 4.41±0.90 nm. In addition, the carbon nanodots were found to have a d4 lattice of 0.24±0.05 nm with the presence of a sp2 graphite carbon (10202) lattice surface.

B) X-ray photoelectron spectroscopy (XPS) measurement

X-ray photoelectron spectroscopy (XPS) in the binding energy range of 0 eV to 1400 eV was measured for the carbon nanodots prepared in Example 4, and the measured X-ray photoelectron spectroscopy and component analysis results are shown in FIG. 4. It is shown in.

Looking at Figure 4, the carbon nano-dots prepared in Example 4 includes a carbon atom (C), nitrogen atom (N) and oxygen atom (O) in a predetermined content, 285.1 ± corresponding to C1s, N1s and O1s, respectively It was found to have major binding peaks of 0.1 eV, 399.5±0.1 eV, and 530.4±0.1 eV.

Specifically, the carbon nano-dots include carbon atoms (C), oxygen atoms (O), and nitrogen atoms (N) at a constant rate of 63.42±0.05 at%, 20.49±0.05 at%, and 16.09±0.05 at%, respectively. It was confirmed. In addition, binding peaks showing 1s binding energy of the carbon atom (C) were observed at 284.4±0.1 eV, 285.6±0.1 eV, and 287.4±0.1 eV. The peaks are peaks representing CN binding energy as binding peaks representing CC/C=C bond, CN/CO bond and C=O bond, respectively. In addition, binding peaks showing 1s binding energy of nitrogen atom (N) at 399.0±0.1 eV and 400.7±0.1 eV were observed. The peaks are binding peaks each showing a pyridyl (C-(NH)-C) / amide (C(=O)NH ₂ ) bond and a pyrrole (C-(NH)-C) bond, respectively, pyridyl (C Peaks representing -(NH)-C) and pyrrole (C-(NH)-C) bonds indicate that nitrogen (N) is doped within carbon nanopoints contained in carbon nanodots, and amide (C(=O)NH ₂ ) The peak representing the binding means that an amide group is introduced to the surface of the carbon nanodot. In addition, as the binding peaks showing the 1s binding energy of the oxygen atom (O) at 530.4±0.1 eV and 531.6±0.1 eV, the peaks are carbonyl (C=O) bond and hydroxy (C-OH)/ether ( COC) It is a peak showing the binding energy.

From the peaks, it can be seen that nitrogen (N) was doped in the carbon nanodots, and amide, hydroxy, carboxyl, and amino groups were present on the surface.

C) Fourier transform infrared spectroscopy (FT-IR) measurement

After preparing KBr pellets for the carbon nanodots of Example 4, a Fourier transform-infrared spectroscopy (FT-IR) analysis was performed in a frequency range of 1,000 to 4,000 cm ^-1 . The results are shown in FIG. 5.

Referring to FIG. 5, the carbon nano-dots of Example 4 show elongation vibration peaks of OH bonds and NH bonds at 3035±0.5 cm ⁻¹ and 3246±0.5 cm ⁻¹ , and at the same time, 2945±0.5 cm ⁻¹ and 2874±0.5. in cm ^-1 was confirmed that each showing a bending vibration peak of the C (= O) ₂ -NH bond (amide bond) in the stretching vibration peak and 1570 ± 0.5 ± 0.5 cm ^-1 and 1658 cm ^-1 of the CH bond. In addition, the carbon nano-dots have peaks representing CN bonds and C=O bonds at 1400±0.5 cm ^-1 , symmetric banding peaks and NH of COC bonds at 1175±0.5 cm ^-1 and 600 to 900 cm ^-1 , respectively. _It can be seen that it has a shaking banding peak of ₂ bonds.

These results indicate that the carbon nanodots are doped with nitrogen atoms (N) therein, and at the same time, there are amide groups, hydroxy groups, carboxyl groups, and amino groups on the surface.

Experimental Example 2.

To evaluate the performance of detecting the aromatic nitro compound of the carbon nanodots according to the present invention, the following experiment was performed.

A) Evaluation of optical properties

Samples were prepared by diluting the carbon nanodots obtained in Examples 1 to 5 and Comparative Example 1 in a concentration of 20 µg/ml in a 0.05M alkaline borate buffer solution (pH: 9.0), respectively. The prepared sample was mounted on a UV-Vis spectrometer, and absorbance was measured in a wavelength range of 250 nm to 700 nm. Then, the sample was irradiated with light in a wavelength range of 350 to 450 nm to measure the exciting peak and emission peak of the sample, and the results are shown in FIG. 6. In addition, in order to confirm the quantum yield of the carbon nano-dots, the quantum yield for 1M sulfuric acid solution in which quinine was dissolved at a wavelength condition of 415 nm was measured as a control, and examples and The quantum yield of the carbon nanodots obtained in the comparative example was compared to Table 2.

As a result, referring to FIG. 6, the carbon nanodots according to the present invention were found to emit light at a wavelength of 484±0.5 nm by excitation in light at a wavelength of 415±0.5 nm, and it was confirmed that the quantum yield was excellent.

Specifically, the carbon nanodots obtained in Example 4 were confirmed to be excited at 415±0.5 nm and 430±0.5 nm wavelengths when irradiating light in a wavelength range of 350 to 450 nm. This was consistent with the absorbance in the 250-700 nm wavelength range for the carbon nanodots. In addition, the carbon nano-dots constantly emit blue-green light at 484±0.5 nm even when the wavelength increases from 350 nm to 450 nm. In comparison, the carbon nanodots obtained in Comparative Example 1 were excited by light at a wavelength of 360±0.5 nm, and emitted blue light at a wavelength of 445±0.5 nm.

This is not only due to the high purity of the carbon nanodots obtained in Example 4, but also due to the uniform and small size of the carbon nanodots and sp2 clusters of carbons, and realized by the synergy effect of the carbon core and the surface or molecular state. Indicates

In addition, as shown in Table 2, the carbon nanodots of Example 4 were confirmed to have excellent quantum yield.

Quantum yield [%] Control 54.0±2 Example 1 62.0±2 Example 2 66.0±2 Example 3 70.0±2 Example 4 75.0±2 Example 5 72.0±2 Comparative Example 1 66.8±2

Specifically, the carbon nanodots of the example showed an improved quantum yield of about 114.8% or more, compared to a control using a quinine sulfate solution, with a quantum yield of about 60% or more. In particular, the carbon nanodots of Examples 3 to 5 in which 200 mol parts or more of the alkylenediamine compound based on 100 mol parts of pyromellitic acid was used at the time of production showed high quantum yield of about 70% or more, and the amount of the alkylenediamine compound used increased. The more the quantum yield increased, the more the pyromellitic acid was used in an amount of 400 mol parts or more based on 100 mol parts, the tendency of the quantum yield to decrease again despite the increase in the amount of the alkylenediamine compound. This means that the generation of carbon nano-dots is optimized at an appropriate concentration of the pyromellitic acid and the alkylenediamine compound, and the production rate of the carbon nano-dots changes according to the concentration of the pyromellitic acid and the alkylenediamine compound, and thus the quantum yield is Indicates controlled.

In addition, it was confirmed that the carbon nanodots of Comparative Example 1 using citric acid as a carbon source showed a 66.8% quantum yield higher than that of the control group but significantly lower than that of the Example. This means that the quantum yield of the carbon nanodots can be adjusted according to the type of carbon source used in the production of the carbon nanodots.

B) Evaluation of selectivity for aromatic nitro compounds

The carbon nanodots obtained in Example 4 were diluted to a concentration of 20 μg/ml in 0.05M alkaline borate buffer solution (pH: 9.0) to prepare a diluted solution. Then, the prepared diluent was mounted on a UV-Vis spectrometer, and irradiated with light at a wavelength of 415 nm, and then measured for UV-Vis fluorescence emission intensity (F ₀ ) at a wavelength of 484 nm. Then, 4-nitrophenol (4-NP), 3-nitrophenol (3-NP), 2-nitrophenol (2-NP), 2-nitroaniline, phenyl boronic acid, ascorbic acid, caffeine, Prepare a sample solution containing ethylenediaminetetraacetic acid (EDTA), catechol, cysteine, glucose, glycine, hydroquinone, and taurine at a concentration of 100 μM, and the sample nanoparticles prepared at room temperature (21±2°C) Each mixture was diluted with a diluted solution, and after 3 minutes, UV-Vis fluorescence intensity (F) at 484±1 nm wavelength of each sample was measured. From the measured value, the ratio of the luminescence intensity change of the carbon nano-dots at a wavelength of 484±1 nm before and after mixing the sample solution was derived, and the results are shown in FIG. 7.

As a result, referring to FIG. 7, it can be seen that the carbon nanodots prepared in Example 4 exhibit the strongest fluorescence quenching effect in the aromatic nitro compound. Specifically, the carbon nano-dots are around 484 nm in 2-nitrophenol (2-NP), 3-nitrophenol (3-NP) and 4-nitrophenol (4-NP) within 3 minutes after mixing. It was found that the emission peak intensity of the carbon nanodots of was decreased, and the F ₀ /F value was increased. In particular, in the case of 4-nitrophenol, the reduction width of the emission peak intensity of the carbon nanodots is very large, and the F ₀ /F value is 5 or more, and as shown in FIG. The decrease was confirmed. In addition, the carbon nano-dots exhibited a fluorescence quenching effect in 2-nitroaniline, catechol, hydroquinone, etc., in addition to the aromatic nitro compound, but the effect was somewhat lower than that of 4-nitrophenol.

From these results, it can be seen that the carbon nanodots of the present invention can selectively detect aromatic nitro compounds.

C) Influence evaluation on pH and ionic strength

Diluted liquid was prepared by diluting the carbon nanodots obtained in Example 4 to a concentration of 20 μg/ml in a buffer solution, and the pH of the diluted liquid was adjusted to 1 to 13. Then, the prepared diluent was mounted on a UV-Vis spectrometer, and irradiated with light at a wavelength of 415 nm, UV-Vis fluorescence emission intensity at a wavelength of 484 nm was measured, and the results are shown in FIG. 8(a).

In addition, the carbon nanodots obtained in Example 4 were separately diluted to a concentration of 20 μg/ml in a 0.05M alkaline borate buffer solution (pH: 9.0) to prepare a diluent, and sodium chloride (NaCl) was added to the prepared diluent from 0.01M to It was added to 2M. Thereafter, the prepared diluent was mounted on a UV-Vis spectrometer, and irradiated with light at a wavelength of 415 nm, UV-Vis fluorescence emission intensity at a wavelength of 484 nm was measured, and the results are shown in FIG. 8(b).

Referring to FIG. 8, it can be seen that the carbon nanodots according to the present invention are stable even in a wide range of pH and ionic strength.

Specifically, referring to (a) of FIG. 8, the carbon nano dot of Example 4 was found to emit high intensity fluorescence at a wavelength of 484±1 nm when the pH was in the range of 4 to 11, When deviating (pH 1~3 and 12~13), fluorescence emission was significantly reduced at 484±1 nm wavelength. In addition, the carbon nano-dots were found to shift the wavelength of the emitted light to a red wavelength when the pH range is 1 to 3. This is due to protonation of the amide group present on the surface of the carbon nanodots, which means that the fluorescence emission of the carbon nanodots is affected in the low pH range.

In addition, referring to (b) of FIG. 8, the carbon nanodots of Example 4 are not affected by the ionic strength even when the ions increase to 2M due to sodium chloride (NaCl) in the solution, and are high at 484±1 nm wavelength. It has been shown to stably emit fluorescence of intensity. This means that the functional group introduced on the surface of the carbon nanodots does not have an ionized form, and thus stably emits fluorescence even under severe conditions in which a high concentration of ions is present.

D) Sensitivity evaluation

The carbon nanodots obtained in Example 4 were diluted to a concentration of 20 μg/ml in 0.05M alkaline borate buffer solution (pH: 9.0) to prepare a diluted solution. Then, the prepared diluent was mounted on a UV-Vis spectrometer, and irradiated with light at a wavelength of 415 nm, and then measured for UV-Vis fluorescence emission intensity (F ₀ ) at a wavelength of 484 nm. Subsequently, a sample solution containing 4-nitrophenol (4-NP) at a concentration of 0.1 to 200 μM was prepared, and each sample solution prepared at room temperature (21±2° C.) was mixed with a diluted solution diluted with carbon nanopoints. . Then, after 3 minutes, the UV-Vis fluorescence intensity (F) at a wavelength of 484±1 nm of the sample was measured. In addition, the obtained calibration curve based on the Stern-Volmer semilog was derived using values measured in the concentration range of 0.1 to 100 μM, and the results are shown in FIG. 9.

Referring to FIG. 9, it can be seen that the carbon nanodots according to the present invention have a high detection ability even for an aromatic nitro compound having a significantly low concentration.

Specifically, referring to (a) of FIG. 9, the carbon nano dot of Example 4 is fluorescence at a wavelength of 484±1 nm as the concentration of 4-nitrophenol (4-NP) increases from 0.1 μM to 200 μM. The emission intensity was found to be lower. In addition, looking at (b) of FIG. 9, the carbon nano dot of Example 4 has a concentration of 4-nitrophenol (4-NP) in a range of 0.1 to 100 μM log (F ₀ /F) = 0.0081· A linear calibration curve of C + 0.0043 (C is the concentration of 4-NP, unit is μM), and the limit of detection (LOD) was found to be 17 nM.

From these results, it can be seen that the carbon nano-dots according to the present invention have excellent remarkability for aromatic nitro compounds, particularly 4-nitrophenol, which is difficult to detect with high solubility in water.

Claims (11)

Contains a hetero ring,
Nitrogen is doped, contains amide groups on the surface,
When measuring UV-vis absorbance, it has an absorption maximum at 410 nm to 430 nm in a wavelength range of 400 to 650 nm,
When measuring light luminescence (PL), it has a fluorescence emission maximum at 475 to 495 nm in a wavelength range of 400 to 740 nm,
The average particle size is 2.8 to 6.4 nm, has a monodispersity of 4.41±0.90 nm,
Carbon nanodots with quantum yields between 70% and 90%.
According to claim 1,
The carbon nano-dots further include one or more of hydroxy, carboxyl and amino groups on the surface.
delete A method for producing a carbon nano dot according to claim 1, comprising performing a hydrothermal reaction of a mixed solution containing pyromellitic acid and an alkylenediamine compound to produce a carbon nano dot.
According to claim 4,
The content of the alkylenediamine compound is 100 to 1,000 mole parts of carbon nanodots relative to 100 mole parts of pyromellitic acid.
According to claim 4,
Hydrothermal reaction time is 1 hour to 10 hours of carbon nano-dots manufacturing method.
Bonding the aromatic nitro compound to the surface of the carbon nanodot by contacting the carbon nanodot according to claim 1 with an aromatic nitro compound; And
A method for detecting an aromatic nitro compound comprising the step of irradiating light to the carbon nano-dots to which the aromatic nitro compound is bound.
The method of claim 7,
Light irradiation is a method of detecting an aromatic nitro compound that irradiates light in a wavelength range of 380 to 450 nm.
The method of claim 7,
The aromatic nitro compound is a method for detecting an aromatic nitro compound that is mixed with a carbon nano dot in a solution state.
The method of claim 9,
The concentration of the aromatic nitro compound is a method for detecting an aromatic nitro compound of 15 nM or more when the concentration of the carbon nanodots is 20 μg/ml.
The method of claim 7,
Aromatic nitro compound is a method for detecting an aromatic nitro compound, characterized in that the compound containing at least one nitro group and at least one hydroxyl group in an aromatic hydrocarbon.

Images