CN114196400A

CN114196400A - Preparation method and application of fluorescent carbon dots and film droplets for colorimetric and ratio detection of phosgene

Info

Publication number: CN114196400A
Application number: CN202111625595.6A
Authority: CN
Inventors: 屈凌波; 张�杰; 孙远强; 杨冉; 李朝辉
Original assignee: Zhengzhou University
Current assignee: Zhengzhou University
Priority date: 2021-12-28
Filing date: 2021-12-28
Publication date: 2022-03-18
Anticipated expiration: 2041-12-28
Also published as: CN114196400B

Abstract

The invention belongs to the field of phosgene detection, relates to a fluorescent carbon dot, and particularly relates to a preparation method and application of a fluorescent carbon dot and a membrane dropping liquid for detecting phosgene in a colorimetric and ratio manner. The fluorescent carbon dots are prepared by using 2-nitro-4-aminodiphenylamine as a precursor and adopting a hydrothermal method. The phosgene is detected by utilizing the change of sunlight and fluorescence color before and after the reaction of the active groups such as amino hydroxyl on the surface of the fluorescent carbon dot and the phosgene. The fluorescent carbon dot film dropping liquid can realize colorimetric and ratio dual response to gaseous phosgene, and has the advantages of easiness in preparation, simplicity in operation, rapidness in response and real-time visualization; on the other hand, the membrane dropping liquid can not only realize real-time liquid phase is visual in the testing process, but also can realize the solid phase of polymer membrane is visual after the solution volatilizes, has improved the not visual shortcoming after the liquid drop detects the end, has prolonged observation time, also can realize that the colour is compared and further analysis after detecting, has good application prospect.

Description

Preparation method and application of fluorescent carbon dot and membrane dropping liquid for colorimetric and ratiometric detection of phosgene

Technical Field

The invention belongs to the field of phosgene detection, relates to a fluorescent carbon dot, and particularly relates to a preparation method and application of a fluorescent carbon dot and a membrane dropping liquid for detecting phosgene in a colorimetric and ratio manner.

Background

Phosgene is a colorless highly toxic gas, has a hay or slightly rotten apple smell at normal temperature, belongs to one of acyl chloride substances, and has an active carbonyl group of acyl chloride, so that the phosgene has an electrophilic property and can react with a nucleophilic reagent; in addition, due to the particularity of the phosgene structure, compared with the common acyl chloride substance, the phosgene not only has more reaction sites, but also has stronger reaction activity; as such, phosgene is widely used as a chemical warfare agent in world war i the first time, with fatality rates as high as 80%; the main reason is that phosgene is very easy to generate acylation reaction with important functional groups such as amino, hydroxyl, sulfydryl and the like in lung tissue protein, so that the lung air-blood barrier is damaged, the permeability of lung capillary vessels is increased, and pulmonary edema is caused. Research shows that lung injury can be caused by exposure to 20 ppm phosgene for 2 min; death was caused by a 30 min duration in 90 ppm phosgene. Despite its great toxicity, phosgene is not prohibited by law in the form of neurotoxic agents such as sarin, soman, tabun and the like, mainly because its very reactive nature makes it used not only as a very destructive chemical warfare agent, but more importantly for industrial use, where it is an extremely important organic intermediate in the synthesis of pesticides, pharmaceuticals, rubbers and dyes. Therefore, phosgene, whether used by terrorists as a chemical agent or accidentally leaked in industrial synthesis, poses a great threat to human health and public safety; as such, it is important to perform rapid, sensitive, and real-time visual detection of phosgene.

Currently, there are many methods that can detect phosgene, such as: gas chromatography, spectrophotometry, electrochemistry, and colorimetric and fluorometric detection methods. Most detection methods, however, require not only expensive instruments but also skilled operations and long time; and for phosgene, a highly toxic gas, the sensitivity and the detection limit of a detection method are high, and most importantly, whether the used detection method can realize real-time detection is also important. This has led to widespread interest in colorimetric and fluorometric assays. At present, a colorimetric and fluorescent detection method generally mainly detects phosgene by using a fluorescent probe, mainly because the fluorescent probe is used as a phosgene sensor, so that the requirements of higher sensitivity and selectivity, lower detection limit and good portability can be met, and real-time detection can be realized. The carbon dots are used as a novel carbon nano material, the surface of the carbon dots contains a large number of active groups to endow the carbon dots with active reaction performance, and the carbon dots have good fluorescence property and can obviously change the sunlight and fluorescence color through the reaction with the surface groups of the carbon dots, so that the necessary condition of the carbon dots as a phosgene fluorescence sensor can be well met; meanwhile, the carbon dots used as a fluorescent sensor for detecting phosgene also have good selectivity and sensitivity, lower detection limit and capability of on-site real-time detection; moreover, the carbon dots also have the advantages of simple preparation method, wide precursor, easy process and purification and the like. Therefore, the carbon dots as the fluorescent sensor for detecting phosgene have good application prospect.

The detection of gaseous phosgene is mainly based on solid-phase device detection, and comprises the following steps: test strips, polymer films and electrospun films; the test paper strip is prepared by soaking, the probes are loaded on the filter paper through adsorption, uniform adsorption and the same adsorption quantity of each piece of the test paper can not be ensured, and a large amount of polluted probes with unknown concentration can be remained in the solution; while polymer films and electrospun films can improve the problem to some extent, the preparation method thereof is more cumbersome, for example: the polymer film is naturally dried in a common container, so that a film with uniform thickness is difficult to obtain, and a film sheet with the same thickness is generally prepared by a film pusher; the electrostatic spinning film is prepared by an electrostatic spinning machine, and the electrostatic spinning film is dangerous due to high voltage, so that the electrostatic spinning film can be used only by skilled operation. Furthermore, there is a similar problem with both test strips and polymeric and electrospun membranes: probes in the solid phase will have a significant decrease in detection sensitivity compared to probes in solution, and either an increase in response time or the actual concentration that can be detected will limit their actual detection capability.

While the liquid phase of the membrane drop has the sensitivity of drop detection of phosgene, including faster response time and lower detection limit; moreover, the membrane dropping liquid is not only limited to real-time liquid phase visualization in the detection process, but also can realize solid phase visualization of the polymer membrane after the solution volatilizes, and can realize color comparison and further analysis fitting after detection. In conclusion, the invention designs the phosgene fluorescent carbon dot with high sensitivity and specificity, provides a membrane dropping liquid detection mode which can be used for quickly detecting in a liquid phase and can be used for long-term visualization of a solid phase, and has good application prospect in actual phosgene detection.

Disclosure of Invention

In order to solve the technical problems, the invention provides a preparation method and application of a fluorescent carbon dot and a membrane dropping liquid for colorimetric and ratiometric detection of phosgene, based on the problems of real-time, online and visual detection, sensitivity of a gas phase detection device and the like which need to be met in the conventional phosgene detection.

The technical scheme of the invention is realized as follows:

a method for preparing a fluorescent carbon dot for colorimetric and ratiometric detection of phosgene comprises the following steps: dissolving 2-nitro-4-aminodiphenylamine in ethanol, and after the heating reaction is finished, eluting and carrying out rotary evaporation to obtain the fluorescent carbon dots.

Further, 0.01 g of 2-nitro-4-aminodiphenylamine was dissolved in 1 mL of ethanol.

Preferably, the heating reaction condition is heating at 180 ℃ for 12 h.

Preferably, the elution is performed by silica gel chromatography and an eluent consisting of petroleum ether and ethyl acetate.

The application of the fluorescent carbon dots prepared by the method in detecting phosgene in a liquid phase comprises the following steps:

(1) preparing a stock solution of the fluorescent carbon dots;

(2) and (2) dissolving the stock solution obtained in the step (1) in a dichloromethane solution, adding the solution to be detected, uniformly mixing, standing for 2 min to obtain a detection solution, and directly observing under sunlight or a 365nm ultraviolet lamp.

Preferably, the solvent in the stock solution of the step (1) is DMSO, and the concentration of the carbon dots is 10 mg/mL; the final concentration of the fluorescent carbon dots in the detection solution of step (2) was 5. mu.g/mL.

Preferably, the detection solution is observed in the sunlight in the step (2), and the color of the solution changes from light yellow to pink in the presence of phosgene; the detection solution was observed under a 365nm ultraviolet lamp, and the fluorescence of the solution changed from yellow-green to orange-red in the presence of phosgene.

The film dropping liquid containing the fluorescent carbon dots prepared by the method comprises the following steps: adding polystyrene into chloroform, stirring until the polystyrene is dissolved, adding carbon dots, and continuously stirring to obtain a uniform fluorescent carbon dot polystyrene film solution, namely a film dropping liquid, wherein the final concentration of the carbon dots in the film dropping liquid is 100 mu g/mL, and the final concentration of the polystyrene is 25 mg/mL.

Further, the application of the membrane dropping liquid in detecting gaseous phosgene is characterized by comprising the following steps: and (3) dripping the film liquid on the carrier to be detected, then placing the carrier to be detected in a gas environment to be detected, and observing the carrier under sunlight or a 365nm ultraviolet lamp.

Preferably, the carrier to be detected is any one of glass, metal, ceramic chip, paper or plastic; the carbon dot film dropping liquid is observed under sunlight, the color of the film dropping liquid is changed from yellow to orange red to purple in the presence of phosgene, the color of the film dropping liquid is observed under an ultraviolet lamp, and the color of the film dropping liquid is changed from bright yellow fluorescence to orange red fluorescence in the presence of phosgene.

The specific operation is as follows: the fluorescent carbon dot film drop is dropped on the inner liner of a bottle cap of a sample and placed in a phosgene environment, the film drop can be changed into mauve from light yellow, bright yellow fluorescence can be changed into orange red fluorescence under 365nm ultraviolet illumination, when a solvent in the film drop is volatilized, the film drop is changed into a polystyrene film, and obvious sunlight and fluorescence color change can still be observed. The phosgene detected by using the membrane dropping liquid prepared by the fluorescent carbon dot has obvious color change, and the naked eye visualization can be realized for 10 ppm of gaseous phosgene within 3 min. And the fluorescent carbon dot and the film dropping liquid prepared by the fluorescent carbon dot only have obvious response to phosgene and do not react with other similar interferents, which indicates that the carbon dot has good selectivity to phosgene.

The invention has the following beneficial effects:

1. the fluorescent carbon dots are prepared by using 2-nitro-4-aminodiphenylamine as a precursor and adopting a hydrothermal method. The phosgene is detected by utilizing the change of sunlight and fluorescence color before and after the reaction of the active groups such as amino hydroxyl on the surface of the fluorescent carbon dot and the phosgene. And a mode for detecting gaseous phosgene by using a simple and quick-response membrane dropping liquid is provided based on the fluorescent carbon dot, and the method specifically comprises the following steps: the fluorescent carbon dots are simple and easy to prepare and purify, have good selectivity and high sensitivity to phosgene, can detect phosgene in a solution for 2 seconds, and have the detection limit as low as 0.214 nM; the fluorescent carbon dots can respond to photo-gas colorimetry and ratio, and sunlight and fluorescent color change are changed from yellow to red, so that the contrast is clear, and observation is facilitated; the membrane dropping liquid prepared by the fluorescent carbon dots is simple and easy to obtain, and only the carbon dots are mixed into the polystyrene membrane solution and then contained in a dropping bottle without complex instruments and operations, and the requirements on detection personnel, fields and carriers are extremely low; the film dropping liquid prepared by the method has the sensitivity of detecting phosgene by liquid drops, and comprises faster response time and lower detection limit; moreover, the membrane dropping liquid is not only limited to real-time liquid phase visualization in the detection process, but also can realize solid phase visualization of the polymer membrane after the solution volatilizes, and can realize color comparison and further analysis fitting after detection. In conclusion, the invention designs the phosgene fluorescent carbon dot with high sensitivity and specificity, provides a membrane dropping liquid detection mode which can be used for quickly detecting in a liquid phase and can be used for long-term visualization of a solid phase, and has good application prospect in actual phosgene detection.

2. The application has strong specificity of the response of the fluorescent carbon point to the light and high sensitivity, and comprises: the detection limit is 0.214 nM, and the response time of phosgene in the solution is less than 2 s; the membrane dropping liquid prepared by using the carbon dots is suitable for various phosgene detection scenes, has lower requirements on carriers, can realize 'dropping and detecting instantly', does not need complex instruments and operations, and has the sensitivity of the liquid drop for detecting phosgene, including faster response time and lower detection limit; in addition, after detection is finished, the solvent in the film dropping liquid can be volatilized to form a solid polymer film, so that the defect that the liquid drops are not visible after detection is finished is overcome, the observation time is prolonged on one hand, and color comparison and further analysis after detection can be realized on the other hand. Therefore, the fluorescent carbon dot and the prepared film dropping liquid have good application value.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is an FT-IR spectrum of a fluorescent carbon dot.

FIG. 2 is an XPS spectrum of fluorescent carbon dots.

FIG. 3 is a graph of the UV-Vis absorption spectra of 5 μ g/mL fluorescent carbon spots reacted with 0-20 μ M triphosgene in methylene chloride for two minutes.

FIG. 4 is a graph showing fluorescence emission spectra at 527 nm and 590 nm wavelengths, respectively, after 5. mu.g/mL of a fluorescent carbon dot was reacted with 0-20. mu.M triphosgene in methylene chloride solution for two minutes, with excitation wavelengths: 438 nm and 500 nm.

FIG. 5 is a linear relationship graph of the ratio of the fluorescence emission intensity of 5. mu.g/mL fluorescent carbon dots to the fluorescence emission intensity of 0-10. mu.M triphosgene at 590 nm and 527 nm in dichloromethane solution, and the triphosgene concentration, with the excitation wavelengths being: 438 nm and 500 nm.

FIG. 6 is a photograph of the color change of 5. mu.g/mL fluorescent carbon spots in the sunlight (top panel) and in the 365nm fluorescence (bottom panel) after the addition of 0-20. mu.M triphosgene to a dichloromethane solution.

FIGS. 7(a), (b) fluorescence emission spectra at 527 nm and 590 nm for 5 μ g/mL fluorescent carbon spots detecting 10 μ M triphosgene and 10 μ M other interferents in dichloromethane; FIG. 7(c) is a histogram of the ratio of the fluorescence intensities at two locations and a color change picture of sunlight and 365nm UV light after phosgene and an interferent are added, the interferent being: acetyl Chloride (CH)₃COCl), oxalyl chloride ((COCl)₂) P-methylbenzenesulfonyl chloride (p-TsCl), thionyl chloride (SOCl)₂) Phosphorus oxychloride (POCl)₃) Formaldehyde (HCHO), Diethyl Chlorophosphate (DCP) and diethyl cyanophosphate (DECP), the excitation wavelengths being: 438 nm and 500 nm.

FIG. 8 is a time-scanning fluorescence spectrum of 5. mu.g/mL fluorescent carbon spots and 10. mu.M triphosgene in dichloromethane, with excitation wavelengths of: 438 nm and 500 nm.

FIG. 9(a) is a schematic diagram of a fluorescent carbon dot membrane drop for detecting gaseous phosgene; FIG. 9(b) is a graph showing the color change of a fluorescent carbon dot film drop exposed to 0-15 ppm gaseous phosgene for 3 min in daylight (upper panel) and under 365nm UV light (lower panel); FIG. 9(c) is a bar graph of RGB values from a daylight picture of fluorescent carbon dot film drops exposed to 0-15 ppm gaseous phosgene for 3 min.

FIG. 10 is a graph of the color change of a fluorescent carbon dot film drop exposed to 20 ppm of gaseous phosgene and other interfering substances in sunlight and under 365nm UV light for 2 min.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.

Example (b): preparation of carbon dots

0.05 g of 2-nitro-4-aminodiphenylamine is weighed, dissolved in 5 mL of ethanol and ultrasonically dissolved. And transferring the obtained uniform solution into a high-pressure reaction kettle, reacting for 12 hours at 180 ℃, and purifying the crude product by a silica gel chromatographic column method after the reaction is finished. The purified solution was subjected to rotary evaporation to remove the solvent to obtain a solid sample, and finally, the solid fluorescent carbon dots were dispersed in dimethyl sulfoxide to prepare a 10 mg/mL carbon dot stock solution. FIG. 1 FT-IR spectrum of fluorescent carbon dots shows 3420, 3198 cm^-1Is the stretching vibration of O-H and N-H, 2922, 2852 cm^-1Stretching vibration corresponding to saturated C-H at 1644, 1510 cm^-1Two characteristic peaks of (A) are the stretching vibration of C = O on the secondary amide, 1599 is-NH₂Flexural vibration of 1132 cm^-1Is C-O telescopic vibration, 758 cm^-1Corresponding to C-H, O-H bending vibrations. FIG. 2 is an XPS spectrum of a carbon dot to investigate the elemental composition and the main chemical bonds of the fluorescent carbon dot of the present invention. FIG. 2(a) shows that the carbon dots consist primarily of C, N, O elements; fig. 2(b) - (d) are high resolution XPS spectra of carbon spots, where C contains mainly three groups of C-C/C = C (284.8 eV), C = O (288.0 eV), C-O/C-N (285.9 eV), N exists mainly as pyridine N, amino N, pyrrole N, and O exists mainly as C = O and C-O. These results all indicate that the carbon dots are successfully synthesized and the surface of the carbon dots contains active groups such as active amino-hydroxyl groups.

Application example 1: detection experiment of fluorescent carbon dots on phosgene in dichloromethane solution

(1) Carbon point to phosgene in solution

The experiments herein all used methylene chloride as the test solvent and, due to the extreme toxicity of phosgene, the phosgene used in the experiments was generated in situ by the less toxic triphosgene instead of phosgene. In addition, XPS (X-ray diffraction) characterization and experiments of a carbon dot structure show that a nitrogen-containing group existing on the carbon dot can directly catalyze triphosgene into phosgene, so that triethylamine is not additionally added when phosgene is detected in a solution, and experiments are directly carried out by using the triphosgene. The response of the carbon dots to different triphosgene concentrations was determined by titration. Firstly, a triphosgene (2 mM) stock solution is diluted into a series of solutions with concentration gradients for later use; then 1. mu.L of fluorescent carbon dots (10 mg/mL) were removed in dichloromethane solution, followed by the addition of 100. mu.L of triphosgene solutions of different concentrations, wherein the final concentration of carbon dots was 5. mu.g/mL and the final concentration of triphosgene was: 0.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16, 18, 20 μ M; and finally, uniformly mixing the solution, standing for two minutes, detecting an ultraviolet-visible absorption spectrum and a fluorescence emission spectrum, and recording the change of sunlight and fluorescence before and after reaction.

As can be seen from fig. 3: the fluorescent carbon dot has an absorption band at 435 nm, a new absorption peak appears at 500 nm with the continuous increase of the triphosgene concentration, the absorbance gradually increases, and the absorption at 435 nm gradually decreases. As can be seen from fig. 4: the emission at the carbon spot was 527 nm before phosgene was added and when phosgene was added, the emission at 527 nm decreased with a new emission peak at 590 nm. FIG. 5 shows that the logarithm of the ratio of the fluorescence intensity at 590 nm to 527 nm is well-linear with the concentration of carbon spots (0-10 μ M) and that the detection limits can be calculated as: 0.214 nM (3. sigma./k). FIG. 6 shows that: the carbon dots were light yellow in dichloromethane and had a yellow-green fluorescence, with increasing phosgene concentration, the solution gradually turned pink and the fluorescence turned orange-red. The phenomena show that the fluorescent carbon dots prepared by the invention can respond to phosgene in a solution, can carry out signal detection through ultraviolet-visible absorption/fluorescence emission spectrums, and most importantly, can realize the visual detection of the phosgene by observing the obvious sunlight and the color change of fluorescence.

(2) Carbon point to phosgene in solution

First, a series of interferent solutions were prepared, each at a concentration of 1 mM, including: acetyl Chloride (CH)₃COCl), oxalyl chloride ((COCl)₂) P-methylbenzenesulfonyl chloride (p-TsCl), thionyl chloride (SOCl)₂) Phosphorus oxychloride (POCl)₃) Formaldehyde (HCHO), Diethyl Chlorophosphate (DCP) and diethyl cyanophosphate (DECP); to a solution of 1. mu.L of carbon dots (10 mg/mL) in methylene chloride was added 100. mu.L of phosgene and other analytes, respectively, and a blank. The final concentration of carbon dots was 5. mu.g/mL, each minuteThe final concentration of the analyte was 10. mu.M. After reacting for 2 min, the fluorescence intensity is measured under the excitation wavelengths of 438 nm and 500 nm respectively, the result is shown in figure 7, the carbon dots do not react with other analytes, the fluorescence intensity of the carbon dots at 527 nm is obviously reduced only in the presence of triphosgene, and a new product emission peak appears at 590 nm. In addition, the change of solution sunlight and fluorescence color can also obviously show that only the carbon dot solution added with triphosgene can obviously change the light yellow solution into pink, and the fluorescence is changed from yellow green into orange red, which all show that the fluorescent carbon dot has better selectivity and can realize the specific detection of phosgene.

(3) Carbon point to phosgene time response experiment

Transferring 2 mL of dichloromethane into the two cuvettes, adding 1 mu L of carbon dot solution (10 mg/mL), mixing uniformly, monitoring the change of the fluorescence values at 527 nm and 590 nm in real time respectively, then rapidly adding triphosgene solution into the cuvettes to the final concentration of 10 mu M, and continuously monitoring the change of the fluorescence values along with time; FIG. 8 illustrates: the carbon point has quick response to phosgene, the fluorescence value at 527 nm is quenched at the moment after phosgene is added, the emission peak of the product reaches the maximum value, and the response time is less than 2 s.

Application example 2: preparation of fluorescent carbon dot film solution

Dissolving 0.1 g of polystyrene in 5 mL of chloroform, and stirring at room temperature to obtain a uniform and transparent solution; then adding 50 mu L of 10 mg/mL carbon dot solution, and continuously stirring uniformly; the prepared film solution was then transferred to a dropper bottle for use.

Application example 3: detection of gaseous phosgene by fluorescent carbon dot film dropping liquid

Taking a glass bottle with the capacity of 500 mL as a reaction container, respectively adding triphosgene and triethylamine with the same concentration and different volumes into a No. 1-4 glass bottle, and fixing the total volume of the detected solution to be 1 mL, wherein the mass ratio of the triphosgene to the triethylamine is 1:1, and finally the triphosgene and the triethylamine form a series of solutions with concentration gradients (0-20 mu M), and the specific experimental steps are as follows: adding a prepared triphosgene solution into a 500 mL glass bottle, sucking the prepared fluorescent carbon dot membrane solution contained in the dropping bottle and dropping the solution onto a solid substance capable of bearing, taking the inner liner of a sample bottle cap as a carrier in the experiment, transferring the sample bottle cap with the membrane dropping liquid into the 500 mL glass bottle, immediately adding a certain amount of triethylamine solution (2 mM) into the sample bottle cap, and covering the bottle cap; after reacting for 3 min, taking out the sample bottle cap, taking out the liner to observe the color change of the film dropping liquid, and analyzing the sunlight color change of the film dropping liquid by using the fluorescent carbon dots after the reaction by using RGB; as can be seen from fig. 9 (b): with the gradual increase of the concentration of phosgene, the obvious color change from yellow to purple can be observed by naked eyes in the fluorescent carbon dot film dropping liquid under the sunlight, and the color changes from bright yellow fluorescent light to orange red under the irradiation of a 365nm ultraviolet lamp; most importantly, the naked eye visualization can be realized for 10 ppm of gaseous phosgene within 3 min; fig. 9(c) shows that the value of the G channel gradually decreased with increasing phosgene concentration, consistent with the experimental phenomenon.

The method specifically comprises the following steps:

no. 1:1 mL acetonitrile as reference;

no. 2: 17 μ L triphosgene solution (2 mM) +17 μ L triethylamine solution (2 mM) +965 μ L acetonitrile;

no. 3: 34 μ L triphosgene solution (2 mM) +34 μ L triethylamine solution (2 mM) +930 μ L acetonitrile;

no. 4: 52 μ L triphosgene solution (2 mM) +52 μ L triethylamine solution (2 mM) +895 μ L acetonitrile;

assuming that triphosgene is completely decomposed into phosgene under the catalysis of triethylamine, the mass ratio of the triphosgene is 1: 3; the above gaseous phosgene concentrations of nos. 1-4, calculated from PV = nRT, are ultimately: 0 ppm, 5 ppm, 10 ppm, 15 ppm; as can be seen from the color change in fig. 9(b), the film drops prepared by using the fluorescent carbon dots of the present invention have the advantages of convenient detection of gaseous phosgene, simple operation, rapid response, low actually measurable phosgene concentration, obvious daylight and fluorescence color change, and particularly, can realize rapid "naked eye" detection at a lower gaseous phosgene concentration; the fluorescent carbon dot and the film dropping liquid thereof have good application prospect in phosgene detection in actual production and life.

Application example 4: selectivity experiment of fluorescent carbon dot film dropping liquid to gaseous phosgene

A 500 mL glass bottle is used as a reaction container, the concentrations of the interferents are all 1 mM, and the volume of the total solution is fixed to be 1 mL; taking 11 sample bottles, respectively as follows: 1-8 additions of 136. mu.L of different interferents and 865. mu.L of acetonitrile, 9 additions of 69. mu.L of 2 mM triphosgene solution and 930. mu.L of acetonitrile, 10 additions of 20 ppm phosgene as per the procedure in example 4, and finally No. 11 without any addition of detection gas as blank reference; the specific detection procedure was the same as in example 4; FIG. 10 shows: only the fluorescent carbon dot film drops in phosgene have obvious color changes whether sunlight or fluorescence, including: the color of the membrane drop liquid changes from yellow to pink under sunlight, and the color of the fluorescence changes from bright yellow to orange red under a 365nm ultraviolet lamp, which shows that the membrane drop liquid prepared by the carbon dot also has good specificity on the detection of the gaseous phosgene.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. a kind of preparation method of the fluorescent carbon dot of colorimetric, ratio detection phosgene, is characterized in that, step is: 2-nitro-4-aminodiphenylamine is dissolved in ethanol, after heating reaction finishes, after washing Fluorescent carbon dots were obtained by dehydration and rotary evaporation.

2. preparation method according to claim 1, is characterized in that: dissolve 0.01 g 2-nitro-4-aminodiphenylamine in every 1 mL of ethanol.

3. The preparation method according to claim 2, characterized in that: the condition of the heating reaction is heating for 12 h at 180 °C.

4. preparation method according to claim 2 is characterized in that: described elution adopts silica gel chromatographic column method, carries out with the eluent that petroleum ether and ethyl acetate are formed.

5. the application of the fluorescent carbon dots prepared by any one of claims 1-4 in the liquid phase to detect phosgene, is characterized in that, the step is:

(1) Prepare the stock solution of fluorescent carbon dots;

(2) Dissolve the stock solution of step (1) in dichloromethane solution, then add the solution to be tested, mix well and place for 2 min to obtain the detection solution, and observe directly under sunlight or 365 nm ultraviolet lamp.

6. The application according to claim 5, characterized in that: the solvent in the storage solution of the step (1) is DMSO, and the concentration of the carbon dots is 10 mg/mL; the fluorescent carbon dots in the detection solution of the step (2) The final concentration is 5 μg/mL.

7. The application according to claim 5, characterized in that: in the step (2), the detection solution is observed under sunlight, and the color of the solution changes from pale yellow to pink when phosgene exists; observed under a 365 nm ultraviolet lamp The solution was detected and its fluorescence changed from yellow-green to orange-red in the presence of phosgene.

8. The film droplet containing the fluorescent carbon dots prepared by any one of claims 1-4, wherein the method for preparing the film droplet is: adding polystyrene into chloroform, stirring until dissolved and then adding carbon dots, and continue to stir to obtain a uniform fluorescent carbon dot polystyrene membrane solution, that is, a membrane drop, the final concentration of carbon dots in the membrane drop is 100 μg/mL, and the final concentration of polystyrene is 25 mg/mL.

9. the application of the film droplet described in claim 8 in detecting gaseous phosgene, it is characterised in that the step is: the film droplet is dropped on the carrier to be tested, then the carrier to be tested is placed in the gas environment to be tested, It can be observed under sunlight or 365 nm UV lamp.

10. The application according to claim 9, characterized in that: the carrier to be tested is any one of glass, metal, porcelain, paper or plastic; the carbon dot film dripping is observed under sunlight, and there is phosgene When the color of the film droplets changed from yellow to orange-red to purple-red, the carbon dot film droplets were observed under ultraviolet light, and the color of the film droplets changed from bright yellow fluorescence to orange-red fluorescence in the presence of phosgene.