Method for detecting hydrazine hydrate by 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe with zero background fluorescence

Abstract

The invention relates to a method for detecting hydrazine hydrate by using a 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe with zero background fluorescence. The method comprises the following steps: carrying out a Schiff base reaction on hydrazine hydrate and a recognition site dicyanovinyl group in the 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe to generate an imine bond as a proton receptor; and a proton transfer process in excited-state molecules is triggered by a proton donor hydroxyl group at an ortho-position of the hydrazine hydrate, so that the hydrazine hydrate is identified and detected. Under irradiation of a 395 nm excitation lamp, after hydrazine hydrate is detected by the probe 2-(4-bromo-2-hydroxybenzylidene) malononitrile, the fluorescence is changed from colorless to obvious blue green, the detection time is 1 s, the detection limit is as low as 0.46 nM, the probe has high selectivity to hydrazine hydrate, and other common 18 potential interferents do not interfere with detection. In addition, by constructing the silicon-based porous sensing material loaded with the probe 2-(4-bromo-2-hydroxybenzylidene) malononitrile, rapid and specific recognition of hydrazine hydrate steam is achieved, and the application prospect is wide.

Description

Technical Field

[0001] The present invention belongs to the field of environmental and hazardous chemical detection, and provides a method for detecting hydrazine hydrate by using a 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe with zero background fluorescence. Technical Background

[0002] Hydrazine hydrate (N 2 H 4 ) is also known as hydrazine. It is an energetic hazardous chemical with characteristics such as high toxicity, strong corrosion, inflammability, and explosiveness. At the same time, hydrazine hydrate is also a highly active base and has strong reducibility, and is widely used in aerospace (rocket and missile fuel) (ACS Sustainable Chemistry & Engineering, 2020, 8: 4457-4463), batteries (ACS Omega, 2020, 5: 28369-28374), chemical industry (The Journal of Organic Chemistry, 2020, 85: 12175-12186), agriculture (Analytical Chemistry, 2019, 91: 7360-7365) and other fields.

[0003] However, due to improper utilization in the industrial production process, it will cause environmental pollution. In addition, after entering the human body through inhalation or skin absorption, it will cause spleen cancer, skin lesions, and skeletal deformities. Moreover, hydrazine hydrate will decompose and cause explosion when exposed to air for a long time or under high temperature for a short time, and has high biological toxicity and danger (Talanta, 2021, 223: 121779-121787). Therefore, realizing highly sensitive detection of hydrazine hydrate is of great significance in the fields of public safety and environmental monitoring (RSC Advances, 2018, 8: 17471-17476).

[0004] In recent years, there have been many conventional methods for detecting hydrazine hydrate, such as spectroscopic / chromatographic analysis, electrochemistry (Sensors and Actuators B: Chemical, 2021, 326: 128717-128729), electrophoresis (Sensors and Actuators B: Chemical, 2020, 321: 128450-128461), colorimetry (Analytical Chemistry, 2017, 89: 9918-9925), and fluorescence (Analytical Chemistry, 2017, 89: 10625-10636) and other technologies. Among them, the fluorescence method has been widely used due to its advantages such as high sensitivity, high selectivity, simple operation, and real-time analysis. Its molecular structure mainly connects recognition sites that can react with hydrazine hydrate on the fluorophore, such as cyano groups, epoxy groups, etc. Commonly used fluorophores include: rhodamine, fluorescein, cyanine, oxazole, and imidazole, etc. However, most fluorescence probes are limited in their applications due to reasons such as high toxicity, low permeability, photobleaching, and susceptibility to interference by small molecules in organisms. Only a few probe molecules can be used for the detection of hydrazine hydrate vapor.

[0005] Starting from the structure of the probe molecule itself, based on the property that hydrazine hydrate is prone to undergo a Schiff base reaction with dicyanovinyl to form an imine bond as a proton acceptor, triggering the excited-state intramolecular proton transfer process, dicyanovinyl is introduced as the recognition site for primary amines, and a hydroxyl group is introduced at the ortho position of the recognition site as a proton donor, constructing an optical probe with zero background fluorescence, realizing the rapid, highly sensitive, and specific detection of hydrazine hydrate. Summary of the Invention

[0006] The object of the present invention is to provide a method for detecting hydrazine hydrate with a 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe having zero background fluorescence. This method is based on the property that hydrazine hydrate is prone to undergo a Schiff base reaction with dicyanovinyl to form an imine bond as a proton acceptor, triggering the excited-state intramolecular proton transfer process. Dicyanovinyl is introduced as the recognition site for primary amines, and a hydroxyl group is introduced at the ortho position of the recognition site as a proton donor, constructing an optical probe 2-(4-bromo-2-hydroxybenzylidene) malononitrile with zero background fluorescence. When irradiated with a lamp with an excitation wavelength of 395 nm, its fluorescence changes from colorless to obvious blue-green, the response speed is 1 s, the detection limit is as low as 0.46 nM, and real-time detection can be achieved. Moreover, it has high selectivity for hydrazine hydrate, and 18 other common potential interferents have no interference on the detection, having broad application prospects.

[0007] A method for detecting hydrazine hydrate using a 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe with zero background fluorescence. The probe is used to detect hydrazine hydrate solution or hydrazine hydrate vapor. The specific operation is carried out according to the following steps:

[0008] Detecting hydrazine hydrate solution:

[0009] a. Dissolve the 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe in dimethyl sulfoxide to prepare a solution with a concentration of 0.014 mol / L to obtain a detection reagent;

[0010] b. Prepare a standard solution of hydrazine hydrate using water as a solvent, with a concentration range of 0 - 3 mmol / L;

[0011] c. Take 200 μL of the detection reagent obtained in step a, dilute it to 1.9 mL with dimethyl sulfoxide. Take 100 μL of each concentration of the hydrazine hydrate standard solution prepared in step b and add them to the detection reagent respectively. After full reaction, under the excitation light of 395 nm, measure the fluorescence spectrum. As the concentration of hydrazine hydrate increases, its fluorescence color changes from colorless to obvious blue-green;

[0012] d. Perform linear fitting on the fluorescence intensity at 463 nm and the corresponding hydrazine hydrate concentration to obtain a standard curve for quantitative analysis of the hydrazine hydrate content in the sample to be measured;

[0013] Detecting hydrazine hydrate vapor:

[0014] a. Dissolve the 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe in dimethyl sulfoxide to prepare a solution with a concentration of 0.014 mol / L to obtain a detection reagent;

[0015] b. Immerse the silicon-based porous material with dimensions of 3×2×2 mm 3 in the probe solution of 2-(4-bromo-2-hydroxybenzylidene) malononitrile obtained in step a to obtain a silicon-based porous sensing material loaded with probe molecules;

[0016] c. Put 5 mL of hydrazine hydrate, ethylenediamine, acetonitrile, methanol, ethanol, acetone, and dimethyl sulfoxide into 30 mL brown sample bottles respectively, seal them and place them at room temperature for 48 h to obtain the saturated atmosphere of each substance;

[0017] d. Use a syringe to separately transfer 1 mL of the saturated atmosphere in step c and spray it on the silicon-based porous sensing material obtained in step b. Observe the change in fluorescence color under the excitation light of 395 nm for rapid qualitative analysis of hydrazine hydrate vapor in the sample to be measured.

[0018] Compared with the prior art, the method for detecting hydrazine hydrate using the 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe with zero background fluorescence according to the present invention has the following beneficial effects:

[0019] Based on the property that hydrazine hydrate is prone to undergo a Schiff base reaction with dicyanovinyl to form an imine bond as a proton acceptor, triggering an excited-state intramolecular proton transfer process, a dicyanovinyl group is introduced as the recognition site for primary amines, and a hydroxyl group is introduced at the ortho position of the recognition site as a proton donor. The constructed optical probe 2-(4-bromo-2-hydroxybenzylidene) malononitrile with zero background fluorescence can achieve specific, highly sensitive, rapid, and visual detection of hydrazine hydrate in the environment and hazardous chemicals, with a detection limit as low as 0.46 nM and a detection time of 1 s. Brief Description of the Drawings

[0020] Figure 1 Fluorescence spectra of the probe 2-(4-bromo-2-hydroxybenzylidene) malononitrile in dimethyl sulfoxide solvent. 200 μL of the probe solution with a concentration of 0.014 mol / L was diluted to 1.9 mL with dimethyl sulfoxide and reacted with 0.1 mL of hydrazine hydrate solutions with concentrations of 0 - 3 mmol / L, respectively.

[0021] Figure 2 Curve showing the change in fluorescence peak intensity at 463 nm with the concentration of hydrazine hydrate after the probe 2-(4-bromo-2-hydroxybenzylidene) malononitrile in dimethyl sulfoxide solvent. 200 μL of the probe solution with a concentration of 0.014 mol / L was diluted to 1.9 mL with dimethyl sulfoxide and reacted with 0.1 mL of hydrazine hydrate solutions with concentrations of 0 - 3 mmol / L, respectively.

[0022] Figure 3 Change in fluorescence intensity at 463 nm with time after the probe 2-(4-bromo-2-hydroxybenzylidene) malononitrile in dimethyl sulfoxide solvent. 200 μL of the probe solution with a concentration of 0.014 mol / L was diluted to 1.9 mL with dimethyl sulfoxide and reacted with 0.1 mL of hydrazine hydrate solution with a concentration of 2 mmol / L.

[0023] Figure 4 Fluorescence spectra of the probe 2-(4-bromo-2-hydroxybenzylidene) malononitrile in dimethyl sulfoxide solvent. 200 μL of the probe solution with a concentration of 0.014 mol / L was diluted to 1.9 mL with dimethyl sulfoxide and reacted with 0.1 mL of 18 kinds of interference solution such as potassium chloride, sodium chloride, ethylenediamine, thiourea, hydrogen peroxide, L-cysteine, sodium bisulfate, etc. with a concentration of 2 mmol / L, respectively.

[0024] Figure 5The fluorescence spectra of the probe 2-(4-bromo-2-hydroxybenzylidene) malononitrile in dimethyl sulfoxide solvent. A 200 μL probe solution with a concentration of 0.014 mol / L was made up to 1.8 mL with dimethyl sulfoxide, and then reacted with 0.1 mL of 18 kinds of interfering substance solutions such as potassium chloride, sodium chloride, ethylenediamine, thiourea, hydrogen peroxide, L-cysteine, sodium bisulfate, etc. with a concentration of 2 mmol / L and 0.1 mL of hydrazine hydrate solution with a concentration of 2 mmol / L;

[0025] Figure 6 Optical images of the silicon-based porous material after being immersed in the probe solution with a concentration of 0.014 mol / L, and its changes were recorded with a mobile phone (iPhone14). Detailed implementation manners

[0026] The following provides specific examples to further illustrate the present invention, but the invention is not limited to these examples.

[0027] Example 1

[0028] a. Dissolve the 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe in dimethyl sulfoxide to prepare a solution with a concentration of 0.014 mol / L to obtain a detection reagent;

[0029] b. Prepare a standard solution of hydrazine hydrate with water as the solvent, and the concentration range is 0 - 3 mmol / L;

[0030] c. Take 200 μL of the detection reagent obtained in step a, make it up to 1.9 mL with dimethyl sulfoxide, take 100 μL of each concentration of the hydrazine hydrate standard solution prepared in step b and add them to the detection reagent respectively. After full reaction, under the excitation light of 395 nm, measure the fluorescence spectrum. As the concentration of hydrazine hydrate increases, its fluorescence color changes from colorless to obvious blue-green; according to the analysis of the fluorescence spectrum diagram (as Figure 1 shown), as the concentration of hydrazine hydrate increases, an emission peak starts to appear at 463 nm, and the emission peak gradually increases.

[0031] Example 2

[0032] a. Dissolve the 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe in dimethyl sulfoxide to prepare a solution with a concentration of 0.014 mol / L to obtain a detection reagent;

[0033] b. Prepare a standard solution of hydrazine hydrate with water as the solvent, and the concentration range is 0 - 3 mmol / L;

[0034] c. Take 200 μL of the detection reagent obtained in step a, dilute it to 1.9 mL with dimethyl sulfoxide. Take 100 μL of each concentration of hydrazine hydrate standard solution prepared in step b and add them to the detection reagent respectively. After sufficient reaction, measure the fluorescence spectrum under 395 nm excitation light. As the concentration of hydrazine hydrate increases, its fluorescence color changes from colorless to obvious blue-green;

[0035] d. Perform linear fitting on the fluorescence intensity at 463 nm and the corresponding hydrazine hydrate concentration to obtain a standard curve for quantitative analysis of the hydrazine hydrate content in the sample to be measured; According to the standard fluorescence spectrum diagram (as shown in Figure 2 ), quantitatively detect the content of hydrazine hydrate in the solution to be measured. The detection limit calculated using the formula LOD = 3δ / K (K = 48005.3267, δ = 7.406) is 0.46 nM.

[0036] Example 3

[0037] a. Dissolve the 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe in dimethyl sulfoxide to prepare a solution with a concentration of 0.014 mol / L to obtain the detection reagent;

[0038] b. Prepare a standard solution of hydrazine hydrate with water as the solvent, and the concentration range is 0 - 3 mmol / L;

[0039] c. Take 200 μL of the detection reagent obtained in step a, dilute it to 1.9 mL with dimethyl sulfoxide. Take 0.1 mL of the 2 mmol / L hydrazine hydrate solution of each concentration of hydrazine hydrate standard solution prepared in step b and add it to the detection reagent. After sufficient reaction, measure the fluorescence spectrum under 395 nm excitation light. As the concentration of hydrazine hydrate increases, its fluorescence color changes from colorless to obvious blue-green;

[0040] d. Make a scatter plot of the fluorescence emission intensity of the solution at 463 nm and the reaction time (as shown in Figure 3 ), and the response time is 1 s.

[0041] Example 4

[0042] Specific recognition detection of hydrazine hydrate by the probe molecule 2-(4-bromo-2-hydroxybenzylidene) malononitrile:

[0043] Dissolve the 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe in dimethyl sulfoxide to prepare a solution with a concentration of 0.014 mol / L to obtain the detection reagent;

[0044] Take 200 μL of the obtained detection reagent and make up the volume to 1.9 mL with dimethyl sulfoxide. Then add 0.1 mL of aqueous solutions of 18 kinds of interfering substances such as 2 mmol / L potassium chloride, sodium chloride, ethylenediamine, thiourea, hydrogen peroxide, L-cysteine, and sodium bisulfate into a fluorescence cuvette. After the reaction, perform fluorescence spectrum testing (as Figure 4 shown). When only hydrazine hydrate is added, a fluorescence emission peak appears at 463 nm. When other common interfering substances are added, there is almost no fluorescence change, indicating that the probe has good specificity for hydrazine hydrate.

[0045] Example 5

[0046] Anti-interference recognition detection of hydrazine hydrate by the probe molecule 2-(4-bromo-2-hydroxybenzylidene) malononitrile:

[0047] Dissolve the probe 2-(4-bromo-2-hydroxybenzylidene) malononitrile in dimethyl sulfoxide, and the concentration of the probe molecule is 0.014 mol / L. Take 200 μL of the probe solution and make up the volume to 1.8 mL.

[0048] Dissolve the 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe in dimethyl sulfoxide to prepare a solution with a concentration of 0.014 mol / L to obtain the detection reagent;

[0049] c. Take 200 μL of the obtained detection reagent and make up the volume to 1.9 mL with dimethyl sulfoxide. Then add 0.1 mL of 2 mmol / L hydrazine hydrate solution and 0.1 mL of aqueous solutions of 18 kinds of interfering substances such as 2 mmol / L potassium chloride, sodium chloride, ethylenediamine, thiourea, hydrogen peroxide, L-cysteine, and sodium bisulfate into a fluorescence cuvette. After the reaction, perform fluorescence spectrum testing (as Figure 5 shown). When only hydrazine hydrate is present, a fluorescence emission peak appears at 463 nm, indicating that the probe has good anti-interference performance for hydrazine hydrate.

[0050] Example 6

[0051] Qualitative determination of hydrazine hydrate vapor:

[0052] a. Dissolve the 2-(4-bromo-2-hydroxybenzylidene) malononitrile probe in dimethyl sulfoxide to prepare a solution with a concentration of 0.014 mol / L to obtain the detection reagent;

[0053] b. Immerse the silicon-based porous material with dimensions of 3×2×2 mm 3 in the probe solution of 2-(4-bromo-2-hydroxybenzylidene) malononitrile obtained in step a to obtain the silicon-based porous sensing material loaded with the probe molecule;

[0054] c. Put 5 mL of hydrazine hydrate, ethylenediamine, acetonitrile, methanol, ethanol, acetone, and dimethyl sulfoxide into 30 mL brown sample bottles respectively, seal them, and place them at room temperature for 48 h to obtain the saturated atmospheres of each substance;

[0055] d. Use a syringe to separately transfer 1 mL of the saturated atmosphere in step c, spray it on the silicon-based porous sensing material obtained in step b, and observe the change in fluorescence color under the 395 nm excitation light (as Figure 6 shown) for the rapid qualitative analysis of hydrazine hydrate vapor in the analyte sample, and record the change in the phenomenon with a mobile phone.

Claims

1. A method for detecting hydrazine hydrate using a 2-(4-bromo-2-hydroxybenzylidene)malononitrile probe with zero background fluorescence, characterized in that The probe is used to detect the hydrazine hydrate solution or hydrazine hydrate vapor. The specific operation is carried out according to the following steps: Detection of hydrazine hydrate solution: a. Dissolve the 2-(4-bromo-2-hydroxybenzylidene)malononitrile probe in dimethyl sulfoxide to prepare a solution with a concentration of 0.014 mol / L to obtain a detection reagent; b. Prepare a standard solution of hydrazine hydrate with water as solvent, with a concentration range of 0-3mmol / L; c. Take 200 μL of the detection reagent obtained in step a, dilute to 1.9 mL with dimethyl sulfoxide, take 100 μL of the hydrazine hydrate standard solution of each concentration prepared in step b and add them to the detection reagent respectively. After sufficient reaction, measure the fluorescence spectrum under 395 nm excitation light. As the concentration of hydrazine hydrate increases, its fluorescence changes from colorless to obvious blue-green; d. Linearly fit the fluorescence intensity at a wavelength of 463 nm to the corresponding hydrazine hydrate concentration to obtain a standard curve for quantitative analysis of the hydrazine hydrate content in the sample to be tested; Detection of hydrazine hydrate vapor: a. Dissolve the 2-(4-bromo-2-hydroxybenzylidene)malononitrile probe in dimethyl sulfoxide to prepare a solution with a concentration of 0.014 mol / L to obtain a detection reagent; b. Set the size to 3×2×2mm 3 The silicon-based porous material is immersed in the probe solution of 2-(4-bromo-2-hydroxybenzylidene)malononitrile obtained in step a to obtain a silicon-based porous sensing material loaded with probe molecules; c. Place 5 mL of hydrazine hydrate, ethylenediamine, acetonitrile, methanol, ethanol, acetone and dimethyl sulfoxide into 30 mL brown sample bottles, seal them and place them at room temperature for 48 hours to obtain a saturated atmosphere of each substance; d. Use a syringe to transfer 1 mL of the saturated atmosphere in step c and spray it on the silicon-based porous sensing material obtained in step b. Under 395 nm excitation light, observe the change in fluorescence color for rapid qualitative analysis of hydrazine hydrate vapor in the sample to be tested.

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