A method and kit for detecting aniline

Abstract

The present invention relates to a method and a kit for detecting aniline, and to the field of fluorescence sensing technology of recyclable fluorescent graphene nanoribbons, and in particular to a method for synthesizing recyclable fluorescent graphene nanoribbons, which can realize the preparation of graphene nanoribbons with precise structure at the gram level and in-situ modification of edge pyrene fluorescent groups, and the edges also alternately have dodecyl carbon chains, so that they have good dispersibility and long-term stability in the liquid phase. The good dispersibility and operability of the fluorescent graphene nanoribbons provide new opportunities for the potential application of the graphene nanoribbons. The recyclable fluorescent graphene nanoribbons of the present invention can achieve a rapid response to aniline, and the fluorescence gradually weakens with the concentration of aniline, has a lower detection limit, and has excellent anti-interference and selectivity.

Description

Technical Field

[0001] The invention relates to the field of chemical substance detection, and in particular to a method and a kit for detecting aniline. Background Art

[0002] Aniline, also known as aniline, aniline oil, and aminobenzene, is one of the most important amine substances. It can be used to make dyes, drugs, resins, and can also be used as a rubber vulcanization accelerator, etc., which has greatly helped human life. Due to the flammability and toxicity of aniline itself, as well as the many dangerous and harmful factors involved in its production process, the safe production research of aniline is imperative. Therefore, the response and selective detection of aniline are of great significance to environmental protection and human health. At present, how to overcome the shortcomings of low sensitivity and poor selectivity and achieve rapid response, high selectivity, and recyclability is still a challenge facing aniline detection. Therefore, there is still a lot of room for development of high sensitivity and selectivity of real-time on-site detection of aniline vapor probes based on efficient sensing mechanisms.

[0003] Based on this, the present invention synthesizes a fluorescent graphene nanoribbon, which has good dispersibility and operability and can be dispersed in an organic reagent to realize recoverable fluorescence detection of aniline. Summary of the invention

[0004] The object of the present invention is to provide a method for detecting aniline, comprising the following steps:

[0005] S1: Provide a fluorescent graphene nanoribbon, wherein the structural formula of the fluorescent graphene nanoribbon is as follows:

[0006]

[0007] In the structural formula, R is a substituent on the benzene ring, and the substituent is selected from branched alkoxy;

[0008] S2: dispersing the graphene nanoribbons in an organic reagent to form a suspension;

[0009] S3: adding the sample to be tested to the suspension to obtain a test solution, and detecting the fluorescence intensity of the test solution at 480-520 nm by a fluorescence spectrometer to calculate the aniline concentration in the sample to be tested.

[0010] In one embodiment, R is a straight chain carbon dodecyloxy group (-OC 12 H 25 ).

[0011] In one embodiment, the organic reagent is one of chloroform, 1,2,4-trichlorobenzene, dichloromethane, toluene and chlorobenzene.

[0012] In one embodiment, the fluorescent graphene nanoribbon is prepared by the following steps:

[0013] S11: Compound I is provided. The molecular formula of Compound I is as follows:

[0014]

[0015] The compound I, pyreneboronic acid pinacol ester, toluene and deionized water are added to a reaction container and mixed evenly, potassium carbonate is added to obtain a first solution, and stirring is continued. Under the protection of an inert gas, methyl trioctyl ammonium chloride and a catalyst are quickly added to the first solution after degassing to obtain a first mixed solution, and heated to react for at least 24 hours under the protection of an inert gas. After the reaction is completed, the organic phase is collected and post-treated to obtain a brown solid compound II. The molecular formula of the compound II is as follows:

[0016]

[0017] S12: Add the compound II and dichloromethane to a reaction container to obtain a second mixed solution, degas, then dissolve FeCl3 in CH3NO2, and dropwise add the solution to the second mixed solution under an inert gas atmosphere, stir, and continue to bubble the inert gas at room temperature for at least 3 days. After the reaction is completed, a black solid compound III is obtained after post-treatment. The molecular formula of the compound III is as follows:

[0018]

[0019] The compound III is a graphene nanoribbon with fluorescence emission,

[0020] In formula I, II and III, R is a substituent on the benzene ring, and the substituent is selected from one of the straight-chain alkoxy groups.

[0021] In one embodiment, the molar ratio of the pyrene borate pinacol ester to the compound I is 1.1-10, the molar ratio of the methyl trioctyl ammonium chloride to the compound I is 0.03-0.15, and the molar ratio of the potassium carbonate to the compound I is 5-10.

[0022] In one embodiment, in the first solution, the volume ratio of toluene to deionized water is 2-3, and the concentration of potassium carbonate is 1-3M.

[0023] In one embodiment, the reaction temperature in step S11 is 100-130° C., and the reaction time is 36-72 hours.

[0024] In one embodiment, the catalyst is Pd(PPh3)4, and the molar ratio of the catalyst to the compound I is 0.03-0.15.

[0025] In one embodiment, for each hydrogen atom removed from compound I in step S12, the amount of FeCl3 used is increased by 7 times or more.

[0026] The present invention also provides a kit for detecting aniline, comprising any one of the above-mentioned compounds III.

[0027] The present invention has the following advantages: it can realize the preparation of gram-level recyclable fluorescent graphene nanoribbons with precise structure, and at the same time, the edges also have alternate dodecyl carbon chains, so that they have good dispersibility and long-term stability in the liquid phase; after being dispersed in an organic reagent, fluorescence quenching sensing of aniline can be realized, and the detection limit is 0.022μM; after adding a small amount of hydrochloric acid for oscillation treatment, the fluorescence intensity of the lower graphene nanoribbon solution returns to the initial value, and aniline can be detected again, and the number of cycles can reach 5 times or more. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings:

[0029] Figure 1 The synthesis flow chart of the fluorescent graphene nanoribbon III of the present invention is shown;

[0030] Figure 2 The XPS energy band comparison spectra of compound II and compound I in the embodiment are shown;

[0031] Figure 3 The Raman spectrum of compound III in the embodiment is shown;

[0032] Figure 4 The transmission electron microscopy image of compound III in the example is shown;

[0033] Figure 5 The fluorescence emission spectrum of compound III in the example is shown;

[0034] Figure 6 The selective fluorescence spectrum of compound III in the embodiment for aniline is shown;

[0035] Figure 7 The fluorescence spectrum of the compound III in the embodiment for recognizing and resisting interference with aniline is shown;

[0036] Figure 8 The fluorescence spectra of compound III in the embodiment for different concentrations of aniline are shown;

[0037] Fig. 9The linear fitting part of the detection of aniline by compound III in the example is shown;

[0038] Fig.10 The spectrum of compound III in the embodiment after recognizing aniline and recovering fluorescence is shown;

[0039] Fig.11 The spectrum of compound III in the example after 5 cycles of detection on aniline is shown. DETAILED DESCRIPTION

[0040] In order to better understand the present invention, the content of the present invention is further explained in conjunction with the following embodiments, but the content of the present invention is not limited to the following embodiments; based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0041] Combination Figure 1-11 In the present invention, fluorescent graphene nanoribbons are prepared by the following method and used for aniline detection:

[0042] S1: Compound I is provided, and the molecular formula of Compound I is as follows:

[0043]

[0044] The compound I, pyreneboronic acid pinacol ester, toluene and deionized water are added to a reaction container and mixed evenly, potassium carbonate is added to obtain a first solution, and stirring is continued. Under the protection of an inert gas, methyl trioctyl ammonium chloride and a catalyst are quickly added to the first solution after degassing to obtain a first mixed solution, and the mixture is heated to react for at least 24 hours under the protection of an inert gas. After the reaction is completed, the organic phase is collected and post-treated to obtain a brown solid compound II. The molecular formula of the compound II is as follows:

[0045]

[0046] See also Figure 2 The obtained compound II was characterized by XPS. The C-Br bond at 70 eV disappeared in the spectrum, indicating that the Br group in compound I was replaced by the pyrene fluorescent group.

[0047] S2: Add the compound II and dichloromethane to a reaction container to obtain a second mixed solution, degas, then dissolve FeCl3 in CH3NO2, and dropwise add the solution to the second mixed solution under an inert gas atmosphere, stir, and continue to bubble the inert gas at room temperature for at least 3 days. After the reaction is completed, a black solid compound III is obtained after post-treatment. The molecular formula of the compound III is as follows:

[0048]

[0049] The compound III is a graphene nanoribbon with fluorescence emission, see Figure 3 and Figure 4 The Raman characterization of the obtained compound III was carried out, and the spectrum clearly showed the G peak, D peak, and 2D peak, indicating that the graphene nanoribbons were successfully prepared; at the same time, the formation of graphene nanoribbons was also clearly shown in the transmission electron microscope;

[0050] In formula I, II, and III, R is a substituent on the benzene ring, and the substituent is selected from one of the linear alkoxy groups. Figure 5 , compound III dispersed in chloroform has a fluorescence emission peak at 500nm.

[0051] The above-mentioned synthesis method innovatively uses the pyrene fluorescent group to replace the bromine group in the precursor, that is, compound I in situ to obtain compound II, and then cyclodehydrogenates the obtained compound II to obtain a fluorescent graphene nanoribbon; this method realizes the preparation of graphene nanoribbons with precise structure in the order of grams and in situ modification of the edge pyrene fluorescent group, and at the same time, the edges of the prepared graphene nanoribbons also have alternating hydrophilic groups, so that it has good dispersibility and long-term stability in the liquid phase. Preferably, the substituent R is a straight-chain carbon dodecyloxy group (-OC 12 H 25 ).

[0052] Preferably, the molar ratio of the pyrene borate pinacol ester to the compound I is 1.1-10, the molar ratio of the methyl trioctyl ammonium chloride to the compound I is 0.03-0.15, and the molar ratio of the potassium carbonate to the compound I is 5-10. The reactants can ensure sufficient reaction within this ratio range, ensuring that the yield of the final compound III is at the gram level.

[0053] Preferably, in the first solution, the volume ratio of toluene to deionized water is 2-3, and the concentration of potassium carbonate is 1-3M.

[0054] Preferably, the reaction temperature in step S1 is 100-130° C., and the reaction time is 36-72 hours.

[0055] Preferably, the reaction solvent in step S2 is anhydrous dichloromethane and anhydrous CH3NO2.

[0056] Preferably, the catalyst is Pd(PPh3)4, and the molar ratio of the catalyst to the compound I is 0.03-0.15. The catalyst effectively ensures the conversion rate and selectivity of the reaction, so that the Br atoms on the compound I can be fully replaced.

[0057] Preferably, for each hydrogen atom removed from the compound I in step S2, the amount of FeCl3 used is increased by 7 times.

[0058] Preferably, the reaction temperature in step S2 is room temperature, and the reaction is carried out for 3-5 days under inert gas bubbling.

[0059] Preferably, the organic solvents or salt compounds used in the present application are in an anhydrous state.

[0060] In the present application, the fluorescent graphene nanoribbons obtained by the above preparation method are used to detect aniline, and the detection steps are as follows:

[0061] S1: Provide a fluorescent graphene nanoribbon, wherein the structural formula of the fluorescent graphene nanoribbon is as follows:

[0062]

[0063] In the structural formula, R is a substituent on the benzene ring, and the substituent is selected from a straight-chain alkoxy group;

[0064] S2: dispersing the graphene nanoribbons in an organic reagent to form a suspension;

[0065] S3: adding the sample to be tested to the suspension to obtain a test solution, and detecting the fluorescence intensity of the test solution at 480-520 nm by a fluorescence spectrometer to calculate the aniline concentration in the sample to be tested.

[0066] Preferably, the organic reagent is one of chloroform, 1,2,4-trichlorobenzene, dichloromethane, toluene and chlorobenzene.

[0067] It should be noted that compound I can be synthesized by chemical methods or purchased through commercial channels.

[0068] Preferably, the sensing ability of compound III to aniline, toluene, 2-nitrotoluene, 3-nitrotoluene, 4-nitrotoluene, 2,4-dinitrotoluene, 2,4,6-trinitrotoluene, nitrobenzene, 1,3-dinitrobenzene, styrene, and aromatic compounds with similar structures but different functional groups of phenol and common organic reagents such as acetonitrile, methanol, acetone, tetrahydrofuran, DMF, DMSO, ethanol and dichloromethane and organic reagents containing heteroatom N elements such as diethylenetriamine, triethylenetetramine and diethylenediamine were tested in chloroform solution; as Figure 6As shown in the figure, when 10 times more selected analytes were added to the chloroform solution of compound III with a concentration of 80 μM, the fluorescence intensity of compound III with aniline added decreased sharply, while the fluorescence intensity of compound III with other analytes added did not change significantly, indicating that compound III can well identify aniline based on its fluorescence intensity and has excellent selectivity. Under the same conditions, the anti-interference experiment of compound III on aniline was also conducted, as shown in the figure. Figure 7 As shown, compound III has excellent anti-interference ability in recognizing aniline.

[0069] For the detection of aniline, compound III was first dispersed in chloroform solvent to form a 1mM suspension. The suspension of compound III (80μL) was placed in a 1.5mL centrifuge tube, and different equivalents of aniline (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4mM) were added, and a volume of 1mL of chloroform solvent was added to test the fluorescence spectrum of compound III (excitation wavelength 400nm). The results are as follows: Figure 8 , 9 As shown, the fluorescence intensity of compound III gradually weakened with the increase of aniline concentration, and the detection limit of compound III for aniline was calculated to be 0.022 μM.

[0070] In the recovery test, a solution of compound III (1 mL, 80 μM) was first prepared in a 1.5 mL centrifuge tube using chloroform solvent; at room temperature, at an excitation wavelength of 400 nm, the fluorescence before and after the addition of aniline solution (80 μL, 800 μM) was measured; after the test, 150 μL of concentrated hydrochloric acid was directly added and shaken vigorously to completely acidify the aniline; 100 μL of deionized water was added to form an organic phase and an aqueous phase, the upper aqueous phase was removed, and the organic phase was washed 3 times with deionized water, and the obtained suspension of compound III was used again for fluorescence sensing; this could be repeated at least 5 times, and the results were as follows: Fig.10 , 11 As shown, in Fig.10 In the figure, it can be seen that the fluorescence emission peak intensity of compound III at 500nm is about 7000. After adding 1 equivalent of aniline, the fluorescence emission intensity weakens to about 2500. After adding 40μL concentrated hydrochloric acid and shaking to separate the organic phase, the fluorescence test of compound III solution shows that it has returned to the initial value. Fig.11 In the figure, we can see that compound III can recover to the initial value after repeated detection of aniline 5 times, which shows the excellent recoverability of compound III in aniline detection.

[0071] Finally, it should be explained that the above-described embodiments are merely preferred examples for clearly illustrating the present invention, but they are not limitations on the implementation schemes of the present invention. Those skilled in the art should understand that the technical features in the above schemes can be combined arbitrarily, and other different forms of modifications or equivalent replacements of some technical features can be made on the basis of the above-mentioned specific implementation schemes. It is impossible to list all implementation schemes here. Therefore, all modifications, improvements, equivalent replacements, etc. derived from the technical schemes of the present invention within the spirit and principles of the present invention should be within the technical scope of the present invention.

Claims

1. A method for detecting aniline, characterized in that: The following steps are involved: S1: Provide a fluorescent graphene nanoribbon, wherein the structural formula of the fluorescent graphene nanoribbon is as follows: In the structural formula, R is a substituent on the benzene ring, and the substituent is a straight-chain alkoxy group; S2: dispersing the graphene nanoribbons in an organic reagent to form a suspension; S3: adding the sample to be tested to the suspension to obtain a test solution, and detecting the fluorescence intensity of the test solution at 480-520 nm by a fluorescence spectrometer to calculate the aniline concentration in the sample to be tested.

2. The method for detecting aniline according to claim 1, characterized in that: The R is a straight-chain carbon dodecyloxy group.

3. The method for detecting aniline according to claim 1, characterized in that: The organic reagent is one of chloroform, 1,2,4-trichlorobenzene, dichloromethane, toluene and chlorobenzene.

4. The method for detecting aniline according to claim 1, characterized in that: The fluorescent graphene nanoribbon is prepared by the following steps: S11: Compound I is provided. The molecular formula of Compound I is as follows: The compound I, pyreneboronic acid pinacol ester, toluene and deionized water are added to a reaction container and mixed evenly, potassium carbonate is added to obtain a first solution, and stirring is continued. Under the protection of an inert gas, methyl trioctyl ammonium chloride and a catalyst are quickly added to the first solution after degassing to obtain a first mixed solution, and heated to react for at least 24 hours under the protection of an inert gas. After the reaction is completed, the organic phase is collected and post-treated to obtain a brown solid compound II. The molecular formula of the compound II is as follows: S12: Add the compound II and dichloromethane to a reaction container to obtain a second mixed solution, degas, then dissolve FeCl3 in CH3NO2, and dropwise add the solution to the second mixed solution under an inert gas atmosphere, stir, and continue to bubble the inert gas at room temperature for at least 3 days. After the reaction is completed, a black solid compound III is obtained after post-treatment. The molecular formula of the compound III is as follows: The compound III is a graphene nanoribbon with fluorescence emission, In formula I, II and III, R is a substituent on the benzene ring, and the substituent is one of the straight-chain alkoxy groups.

5. The method for detecting aniline according to claim 4, characterized in that: The molar ratio of the pyrene boric acid pinacol ester to the compound I is 1.1-10, the molar ratio of the methyl trioctyl ammonium chloride to the compound I is 0.03-0.15, and the molar ratio of the potassium carbonate to the compound I is 5-10.

6. The method for detecting aniline according to claim 4, characterized in that: In the first solution, the volume ratio of toluene to deionized water is 2-3, and the concentration of potassium carbonate is 1-3M.

7. The method for detecting aniline according to claim 4, characterized in that: The reaction temperature in step S11 is 100-130° C., and the reaction time is 36-72 hours.

8. The method for detecting aniline according to claim 4, characterized in that: The catalyst is Pd(PPh3)4, and the molar ratio of the catalyst to the compound I is 0.03-0.

15.

9. The method for detecting aniline according to claim 4, characterized in that: In step S12, for every hydrogen atom removed from compound II, the amount of FeCl3 used is increased by 7 times or more.

10. A kit for detecting aniline, characterized in that: Including compound III according to any one of claims 1-9.

Images