Fluorescent probe for visually detecting various amines and application

Abstract

The invention discloses an application of a cyclic chalcone cationic compound as a fluorescent probe in detection of amine molecules, the structural formula of the cyclic chalcone cationic compound is as shown in formula I. The probe can realize quantitative detection of the amine molecules through fluorescence intensity. Qualitative detection of amine molecules is realized through fluorescence color difference after response with different amines, and difference visual detection of different amine molecules is realized. Detection carriers such as filter paper developed by using the probe have the advantages of simplicity in operation, low cost, real-time detection and the like, and have the potential of large-scale popularization and application.

Description

[Technical Field]

[0001] This invention belongs to the field of fluorescent probes, specifically relating to a fluorescent probe based on the cyclic chalcone cation structure that can visually detect a variety of amines and its applications. [Background Technology]

[0002] Amine compounds, as important biomarkers, play a crucial role in food quality testing and disease diagnosis. They also have wide applications in chemical, pharmaceutical, agricultural, and materials fields. In industrial safety and quality control, many amine compounds are key intermediates in the synthesis of dyes, pesticides, and pharmaceuticals; however, their residues or volatilization can lead to decreased product purity or production safety hazards, requiring strict monitoring. In environmental and health risk control, some amines are highly carcinogenic and can enter the ecological environment through industrial wastewater, exhaust gases, or food additives, threatening human health; therefore, highly sensitive detection is necessary to comply with environmental regulations. In biomedical research, abnormal concentrations of amine neurotransmitters are associated with various diseases, making accurate detection crucial for pathological research and diagnosis. Therefore, developing highly sensitive and selective amine compound detection technologies is of significant value for both scientific research and industrial applications.

[0003] Currently, commonly used methods for the analysis of amines include gas chromatography-mass spectrometry, electrochemistry, high-performance liquid chromatography, and spectrophotometry. However, difficulties in sample preparation, challenges in real-time monitoring, and cumbersome procedures limit the application of these methods. Fluorescent probe-based detection methods, with their advantages of good visualization, simple operation, high specificity, and real-time in-situ detection, are widely used for the monitoring of small molecule guests. Commonly used mechanisms for fluorescent probe detection of amines include deprotonation, Schiff base reaction, ammonolysis, nucleophilic addition, and cyclization. However, probe molecules capable of simultaneously detecting multiple amine compounds with good visualization are scarce. Therefore, developing novel probes that are easy to synthesize and exhibit different recognition phenomena for multiple amine molecules is of great significance for fields such as food and environmental monitoring. [Summary of the Invention]

[0004] The purpose of this invention is to address the above-mentioned technical analysis and existing problems by providing a fluorescent probe for the visual detection of multiple amines and its application.

[0005] The structural formula of the cationic pyridine probe containing the cyclic chalcone structure is shown in Formula I, which consists of a chalcone linked to a pyridine salt group:

[0006]

[0007] The preparation method includes the following steps:

[0008] The synthesis route is as follows:

[0009]

[0010] (1) Substituted benzaldehyde reacts with 5-bromo-1-indanone under alkaline catalysis to give intermediate product A;

[0011] (2) Intermediate product A reacts with 4-pyridineboronic acid via a coupling reaction to obtain intermediate product B;

[0012] (3) Intermediate product B reacts with a multifunctional halogenated alkane (containing hydroxyl / sulfonic acid group) to obtain target product I.

[0013] In step (1), the base is selected from sodium hydroxide, potassium hydroxide or sodium tert-butoxide, the reaction solvent is selected from methanol or ethanol, the molar ratio of substituted benzaldehyde to 5-bromo-1-indanone and base is 1:1 to 1.5:1.5 to 3.5, the reaction time is 2 to 6 hours, and the reaction temperature is 20 to 45°C.

[0014] In step (2), the solvent is ethylene glycol dimethyl ether / water or ethanol / toluene / water, the molar ratio of intermediate product A to 4-pyridineboronic acid is 1:1 to 1.3, the reaction time is 8 to 24 h, the reaction temperature is 80 to 120 °C, and intermediate product B is obtained by SUZUKI coupling reaction;

[0015] In step (3), the solvent is acetonitrile, the molar ratio of intermediate product B to polyfunctional halogenated alkanes (containing hydroxyl / sulfonic acid groups) is 1:1.2-2.0, the reaction time is 6-18 h, and the reaction temperature is 60-85 °C to obtain intermediate product I;

[0016] The second objective of this invention is to provide an application of a cationic fluorescent probe based on a cyclic chalcone structure in the detection of organic amine compounds;

[0017] An application of a cationic pyridinium salt compound containing a cyclic chalcone structure as a fluorescent probe in the detection of organic amines is characterized by enhanced fluorescence in an organic amine environment. Quantitative analysis of amine molecules can be achieved by detecting the fluorescence intensity. Due to the strong intramolecular charge transfer effect, this type of fluorescent probe exhibits polar sensitivity, with significant variations in emission wavelengths in different polar environments. Based on this characteristic, the probe can visually distinguish amine compounds with different structures through significant differences in fluorescence color, providing a highly sensitive and selective analytical tool for the rapid detection of organic amines.

[0018] The application of the fluorescent probe in the detection of amine compounds is characterized by the ability to prepare the probe into test carriers such as test strips, hydrogels, and plastic films to detect amine compounds under different environments.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. This method combines quantitative fluorescence intensity detection with qualitative emission wavelength detection, providing a reliable solution for differentiating multi-component amine compounds and overcoming the technical bottlenecks of traditional amine fluorescent probes in detecting different types of amine molecules. It demonstrates significant application value in scenarios such as food safety supervision and industrial process control. Furthermore, the method is simple to operate, low in cost, and technically and economically feasible for industrial-scale application.

[0021] 2. Based on the differences in emission wavelengths, the probe can distinguish various amine compounds with the naked eye through changes in fluorescence color, without the need for complex instruments. Thanks to the diversity and portability of the material system, this technology can meet the rapid detection needs in different scenarios such as gas monitoring and high humidity environments. [Attached Image Description]

[0022] Figure 1 This is the 1H NMR spectrum of compound A-1 prepared in Example 1.

[0023] Figure 2 This is the 1H NMR spectrum of compound B-1 prepared in Example 2.

[0024] Figure 3 This is the 1H NMR spectrum of compound I-1 prepared in Example 3.

[0025] Figure 4 This is the carbon NMR spectrum of compound I-1 prepared in Example 3.

[0026] Figure 5 This is a high-resolution mass spectrum of compound I-1 prepared in Example 3.

[0027] Figure 6 This is a comparison of the fluorescence intensity of the I-1 test strip after responding to different concentrations of triethylamine, as well as a graph showing the changes in the test strip. (Example 5)

[0028] Figure 7 This is a comparison of the fluorescence intensity of the I-1 test strip after responding to different concentrations of n-propylamine, as well as a graph showing the changes in the test strip. (Example 6)

[0029] Figure 8 The fluorescence emission spectra of the I-1 test paper after responding to different amines, as tested in Example 7.

[0030] Figure 9 These are photographs of the I-1 test strips used in Example 8, showing their responses to fresh and spoiled fish. [Specific implementation method]

[0031] The present invention will be described below through specific embodiments, but the present invention is not limited thereto.

[0032] Unless otherwise specified, the experimental methods described in the following examples are all conventional methods; the reagents and solvents mentioned can be purchased commercially.

[0033]

Example 1

[0034] Preparation of intermediate A-1:

[0035]

[0036] 3.11 g (21.0 mmol) of 4-dimethylaminobenzaldehyde, 4.03 g (19.0 mmol) of 5-bromo-1-indanone, and 2.52 g (63.0 mmol) of NaOH were added to a 250 mL flask, followed by the addition of 120 mL of ethanol. The mixture was stirred at 25 °C for 3 hours, and the reaction was monitored by TLC until complete. After cooling to room temperature, the crude product precipitated, and recrystallization yielded 5.69 g of orange powder, which is intermediate A-1, with a yield of 87.5%. 1 H NMR(400MHz,Chloroform-d)δ7.68(d,J=8.1Hz,1H),7.63(d,J=1.6Hz,1H),7.61–7 .56(m,1H),7.54–7.45(m,3H),6.70–6.64(m,2H),3.94–3.87(m,2H),2.99(s,6H).

[0037]

Example 2

[0038] Preparation of intermediate B-1:

[0039]

[0040] 0.562 g (1.7 mmol) of intermediate A-1, 0.238 g (2.0 mmol) of 4-pyridineboronic acid, (0.002 g, 0.2% wt) of tetrakis(triphenylphosphine)palladium, and 2.35 g (17.0 mmol) of potassium carbonate were added to a 50 mL flask. Then, 18 mL of oxygen-free ethylene glycol dimethyl ether and water (volume ratio 1.5:1) were added. The mixture was refluxed and stirred for 8 hours under N2 protection, and the reaction was monitored by TLC until complete. After cooling to room temperature, the mixture was extracted with ethyl acetate and water. The organic phase was collected, dried, and the solvent was removed by rotary evaporation to obtain the crude product. After column chromatography purification, 0.485 g of orange powder, i.e., intermediate B-1, was obtained, with a yield of 83.8%. 1H NMR(500MHz,Chloroform-d)δ8.71–8.59(m,2H),7.92(d,J=7.8Hz,1H),7.74–7.68(m,1H),7.62–7.57(m,2H ),7.56–7.51(m,2H),7.51–7.46(m,2H),6.71–6.65(m,2H),4.07–3.88(m,2H),2.99(s,6H).HRMS:m / z[M+H] + calcd for C 23 H 21 N2O + Theoretical value: 341.1649, Actual value: 341.1649.

[0041]

Example 3

[0042] Preparation of target product I-1:

[0043]

[0044] 0.11 g (0.3 mmol) of intermediate B-1, 0.02 mL (0.3 mmol) of 2-bromo-1-propanol and 8 mL of acetonitrile were placed in a 25 mL flask and stirred at 90 °C for 12 hours. The reaction was monitored by TLC until complete. After cooling to room temperature, the crude product precipitated. Washing with a small amount of acetonitrile yielded 0.11 g of dark red powder I-1, with a yield of 94.3%. 1 H NMR (500MHz, DMSO-d6)

[0045] δ9.12(d,J=6.6Hz,2H),8.62(d,J=6.9Hz,2H),8.35(s,1H),8.12(dd,J=7.9,1.6Hz,1H),7.96(d,J=8.0Hz,1H),7.66(d,J=8.6 Hz,2H),7.54(d,J=2.1Hz,1H),6.83(d,J=8.6Hz,2H),4.70(t,J=4.9Hz,2H),4.14(s,2H),3.92(t,J=4.9Hz,2H),3.04(s,6H). 13 CNMR(126MHz,DMSO-d6)δ192.42,154.60,151.84,150.74,145.87,140.86,138.98,135.64,133.4 7,129.65,128.04,126.78,125.30,124.56,122.43,112.47,62.89,60.54,32.77.HRMS:m / z[M+H]

[0046] + calcd for C 25 H 25 N2O2 + Theoretical value: 385.1911, Actual value: 385.1908.

[0047]

Example 4

[0048] Prepare a 10 μmol / L solution of I⁻ and test its UV-Vis absorption spectrum and fluorescence emission spectrum.

[0049] The photophysical properties of the target molecule I-1 solution in the above embodiments are shown in Table 1:

[0050] Table 1: Photophysical properties of I-1

[0051]

[0052]

[0053]

Example 5

[0054] Filter paper was immersed in a 0.1 mM dichloromethane solution (I-1), air-dried, and then cut into 5 × 1 cm pieces to prepare test strips. The test strips were placed in a vial containing triphenylamine vapor, and the experimental results were as follows. Figure 6 As shown, the test strip exhibits pink fluorescence at 553 nm, which increases with increasing amine vapor concentration. Therefore, the I-1 test strip provides good visual detection of amine molecules and allows for quantitative detection of amine molecules through fluorescence intensity.

[0055]

Example 6

[0056] The test strip was placed in a vial containing n-propylamine vapor, and the experimental results were as follows. Figure 7 As shown, the test strip exhibits orange-yellow fluorescence at 530 nm, which increases with increasing amine vapor concentration. Therefore, the I-1 test strip provides good visual detection of amine molecules and allows for quantitative detection of amine molecules through fluorescence intensity.

[0057]

Example 7

[0058] The test strip was placed in a small bottle containing vapors of various saturated amines (diethylamine, hydrazine hydrate, cyclohexanediamine, dipropylamine, triethylamine, n-hexylamine, ethylenediamine, n-propylamine). The experimental results are as follows. Figure 8 As shown, I-1 exhibits different color responses to different amine molecules. Therefore, the I-1 test strip can provide good visual detection of differences among different amine molecules, and can achieve qualitative detection of amine molecules through changes in fluorescence color.

[0059]

Example 8

[0060] Place the I-1 test strip into a small bottle containing both fresh and spoiled fish. After 5 minutes, irradiate the test strip with a 365nm wavelength ultraviolet lamp. The experimental results are as follows. Figure 9 As shown, the test strip in the bottle containing spoiled fish can be clearly observed to emit pink fluorescence. Therefore, the I-1 test strip can be used in food testing, enabling real-time and visual detection, and has great application potential.

Claims

1. The application of a cyclic chalcone cationic compound as a fluorescent probe in the detection of amine molecules, characterized in that, The structural formula of the cyclic chalcone cationic compound is shown in Formula I.

2. The application of a cyclic chalcone cationic compound as described in claim 1 as a fluorescent probe in the detection of amine molecules, characterized in that, Fluorescent probes can achieve quantitative detection of amine molecules through fluorescence intensity, and can achieve visual qualitative and differential detection of amine molecules by using different fluorescence emission wavelengths and colors after responding to different amine molecules.

3. The application of the fluorescent probe as described in claim 2 in the detection of amine molecules, characterized in that, The probes can be prepared into test carriers such as test strips, hydrogels, and plastic films to detect amines in different environments such as food testing and industrial production.

Images