Fluorescent probe based on naphthalimide-1,4,7-triazaheptane and preparation method and application thereof

Abstract

The present invention discloses a fluorescent probe based on naphthalimide-1,4,7-triazaheptane and its preparation method and application. The fluorescent probe has the following chemical structural formula: The different responsiveness of the fluorescent probe NP of the present invention to phosgene leads to an obvious emission-type turn-on response, indicating that the fluorescent probe NP has high selectivity for phosgene. In addition, a practical phosgene online detection sensor is prepared by loading the probe NP on a test paper, which can detect trace phosgene at a concentration lower than 1ppm. This strategy provides a safe and simple way to quickly detect extremely low levels of phosgene. The successful development of the fluorescent probe NP has opened up new possibilities for the design and production of advanced phosgene sensing. The fluorescent probe NP of the present invention is obtained by a substitution reaction of 1,4,7-triazaheptane, and has the advantages of a simple preparation method and easy availability.

Description

Technical Field

[0001] The present invention relates to the technical field of phosgene detection, and in particular to a fluorescent probe based on naphthylimide-1,4,7-triazaheptane, and a preparation method and application thereof. Background Art

[0002] Phosgene (COCl2) is a highly toxic gas. Exposure to phosgene can cause severe damage to the lungs, chemical burns to the skin and eyes, and may even result in death. The approximate lethal dose of phosgene for humans is 500 ppm / min. However, despite its lethality, phosgene is also a valuable industrial reagent that has been widely used in the production of various compounds such as dyes, pharmaceuticals, and pesticides due to its easy availability. Therefore, it is of great significance to discover a rapid and sensitive phosgene detection technology to prevent potential applications in accidental leaks in industry.

[0003] There are various detection techniques for phosgene, such as electrochemical methods, gas chromatography-mass spectrometry (GC-MS), high performance liquid chromatography (HPLC), and colorimetry. However, these methods have significant disadvantages such as long analysis time, complex sample processing, poor portability, and high cost. In contrast, fluorescence-based detection techniques have the following advantages, such as real-time response, low cost, convenience, and high sensitivity. Many fluorescent probes containing fluorescent groups such as amine-containing coumarins, naphthylimide, BODIPY, rhodamine, tetraphenylethylene, anthracene carboxylic imide, and recognition groups such as amino (imine) or hydroxyl, o-phenylenediamine, 2-aminoaniline, ethylenediamine, and oxime have been used to detect phosgene.

[0004] Although significant progress has been made in the research and development of phosgene fluorescent probes, it remains a huge challenge to develop phosgene fluorescent probes with high sensitivity. Summary of the invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, propose a fluorescent probe based on naphthalimide-1,4,7-triazaheptane and its preparation method and application, and solve the technical problem of low sensitivity of phosgene fluorescent probe in the prior art.

[0006] In a first aspect, the present invention provides a fluorescent probe (NP) based on naphthalimide-1,4,7-triazaheptane, the chemical structure of which is as follows:

[0007]

[0008] In a second aspect, the present invention provides a method for preparing a fluorescent probe based on naphthalimide-1,4,7-triazaheptane, comprising the following steps:

[0009] Compound 1 is reacted with compound 2 in a solvent to obtain a fluorescent probe based on naphthalimide-1,4,7-triazaheptane; the specific reaction formula is as follows:

[0010]

[0011] In a third aspect, the present invention provides the use of the above-mentioned fluorescent probe based on naphthylimide-1,4,7-triazaheptane in phosgene detection.

[0012] Compared with the prior art, the beneficial effects of the present invention include:

[0013] The different responsiveness of the fluorescent probe NP of the present invention to phosgene leads to an obvious emission-type turn-on response, indicating that the fluorescent probe NP has high selectivity for phosgene. In addition, a practical phosgene online detection sensor is prepared by loading the probe NP on a test paper, which can detect trace phosgene at a concentration below 1 ppm. This strategy provides a safe and simple way to quickly detect extremely low levels of phosgene. The successful development of the fluorescent probe NP has opened up new possibilities for the design and production of advanced phosgene sensing. The fluorescent probe NP of the present invention is obtained by a substitution reaction of 1,4,7-triazaheptane, and has the advantages of a simple preparation method and easy availability. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a diagram showing the mechanism of action of the fluorescent probe NP and phosgene provided in Example 1 of the present invention;

[0015] Figure 2 The UV-visible light spectrum (a) and fluorescence spectrum (b) of the fluorescent probe NP (10 μM) provided in Example 1 of the present invention before and after the response to phosgene (100 μM);

[0016] Figure 3 This is a response time diagram of the fluorescent probe NP (10 μM) provided in Example 1 of the present invention to different concentrations of phosgene;

[0017] Figure 4 The UV-visible titration spectrum (a) and the fluorescence titration spectrum (b) of the fluorescent probe NP (10 μM) and 0-20 μM phosgene provided in Example 1 of the present invention are shown;

[0018] Figure 5 is a linear relationship diagram between the fluorescent probe NP (10 μM) provided in Example 1 of the present invention and 0-10 μM phosgene;

[0019] Figure 6This is a test diagram of the selectivity of the fluorescent probe NP provided in Example 1 of the present invention for other analytes; wherein 1 to 9 are phosgene, DCP, POCl3, (COCl)2, SOCl2, TsCl, CH3COCl, SO2Cl2 and HBr, respectively;

[0020] Figure 7 It is an anti-interference test diagram of the fluorescent probe NP provided in Example 1 of the present invention on other analytes; wherein, the strong fluorescence groups in 1 to 9 are respectively fluorescent probe NP+phosgene, fluorescent probe NP+phosgene+DCP, fluorescent probe NP+phosgene+POCl3, fluorescent probe NP+phosgene+(COCl)2, fluorescent probe NP+phosgene+SOCl2, fluorescent probe NP+phosgene+TsCl, fluorescent probe NP+phosgene+CH3COCl, fluorescent probe NP+phosgene+SO2Cl2 and fluorescent probe NP+phosgene+HBr, and the weak fluorescence group is fluorescent probe NP, and the excitation wavelength is 460nm;

[0021] Figure 8 is a fluorescence intensity diagram of the fluorescent probe NP provided in Example 1 of the present invention in response to phosgene under continuous excitation;

[0022] Fig. 9 The fluorescence color changes of the phosgene detection test paper made of the fluorescent probe NP provided in Example 1 of the present invention at different phosgene concentrations; wherein the gas phase phosgene concentrations are 0, 1, 5, 10, 20, and 50 ppm from left to right;

[0023] Fig.10 This is a selectivity test of the phosgene detection test paper made of the fluorescent probe NP provided in Example 1 of the present invention against other interferents; wherein, from left to right, they are POCl3, SOCl2, TsCl, SO2Cl2, (COCl)2, CH3COCl, HBr, DCP and phosgene. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] In a first aspect, the present invention provides a fluorescent probe (NP) based on naphthalimide-1,4,7-triazaheptane, the chemical structure of which is as follows:

[0026]

[0027] The present invention provides a fluorescent probe with high sensitivity, low detection limit and rapid response. Figure 1, the specific mechanism of action is as follows: the fluorescent probe NP uses 1,4,7-triazaheptane as a recognition group, which can provide multiple nitrogen atoms with lone pairs of electrons. The strong electron donation ability of 1,4,7-triazaheptane suppresses the fluorescence emission of the fluorescent probe NP through the light-induced electron transfer effect (PET); after phosgene reacts with the fluorescent probe NP, a product (NP-S) is generated by the reaction of phosgene with two nitrogen atoms. This reaction weakens the electron donation ability and suppresses the PET effect. Therefore, the ICT effect occurs, resulting in enhanced fluorescence. The fluorescent probe NP of the present invention has significant selectivity for phosgene in both solution and gas phase, making it potentially widely used as a phosgene sensor.

[0028] In a second aspect, the present invention provides a method for preparing a fluorescent probe based on naphthalimide-1,4,7-triazaheptane, comprising the following steps:

[0029] Compound 1 is reacted with compound 2 in a solvent to obtain a fluorescent probe based on naphthalimide-1,4,7-triazaheptane; the specific reaction formula is as follows:

[0030]

[0031] In the present invention, a bromine atom on the naphthalene ring of compound 1 replaces 1,4,7-triazacycloalkane to obtain a fluorescent probe NP, the preparation process is simple, and the product is easy to obtain.

[0032] In this embodiment, the molar ratio of compound 1 to compound 2 is 1:(0.1-10), further 1:2.

[0033] In this embodiment, the solvent is methoxyethanol. Further, the usage ratio of compound 1 to the solvent is 1 g: (50-200) mL, further 1 g: 100 mL.

[0034] In this embodiment, the reaction temperature is 100 to 140° C., preferably 120° C., and the reaction time is 8 to 24 hours, preferably 12 hours.

[0035] In a third aspect, the present invention provides the use of the above-mentioned fluorescent probe based on naphthylimide-1,4,7-triazaheptane in phosgene detection.

[0036] In this embodiment, the above-mentioned phosgene detection includes phosgene detection in solution or phosgene detection in gas phase.

[0037] In this embodiment, the phosgene detection includes qualitative detection or quantitative detection.

[0038] The linear range of quantitative detection is 0-10μM.

[0039] Among them, qualitative detection is achieved by making a fluorescent probe based on naphthalimide-1,4,7-triazaheptane into a phosgene detection test paper. The present invention uses the fluorescent probe NP to prepare a portable phosgene detection test paper, which realizes portable and highly sensitive phosgene detection. Due to its high sensitivity and selectivity, the phosgene detection test paper has good potential for on-site and rapid detection of gas-phase phosgene in actual environments.

[0040] To avoid redundancy, in the following examples of the present invention, compound 1 was prepared by literature methods, and other reagents used for synthesis were from commercial suppliers (Andrich-Sigma) and were not further purified. Nuclear magnetic resonance spectra (NMR) were recorded by Bruker 400MHz, the solvent was CDCl3, tetramethylsilane (TMS) was used as an internal standard, and the unit of chemical shift measurement was ppm. UV / visible absorption spectra and fluorescence spectra were recorded by Hitachi F-3700 UV / visible spectrometer and Hitachi F-2500 fluorescence photometer at room temperature, respectively. LCMS spectra were obtained by Waters HPLC system.

[0041] Example 1

[0042] Compound 1 (100 mg, 0.26 mmol) and compound 2 (66 mg, 0.52 mmol) were mixed in 10 mL of methoxyethanol, and then stirred at 120°C for 12 h. The reaction solution was extracted with dichloromethane three times, and the residue was obtained by vacuum distillation. The residue was then purified by silica gel column chromatography (dichloromethane: methanol as eluent, volume ratio of 30:1) to obtain 37 mg of the target product. (yield = 32.9%). 1 HNMR(400MHz,Chloroform-d)δ8.81(d,J=8.5Hz,1H),8.66–8.55(m,1H),8.50(dd,J=8.2,3.4Hz,1H),7.73(t,J=7.6Hz,1H),7.50–7. 41(m,1H),4.33(t,J=6.9Hz,2H),3.68(dd,J=13.9,9.4Hz,9H),3.19(d,J=31.7Hz,7H),2.70(t,J=7.0Hz,2H),2.61(d,J=5.0Hz,4H). 13 CNMR(101MHz,Chloroform-d)δ164.35,163.74,153.88,132.13,131.45,130.33,127.34,126.1 8,123.24,117.26,67.06,56.15,55.81,53.81,52.03,46.07,45.20,37.14,29.71.MS=437.24.

[0043] Phosgene detection in solution of test group 1

[0044] Phosgene is prepared by adding the less toxic precursor triphosgene to a dichloromethane solution of triethylamine (TEA) at a volume concentration of 0.1%. The stock solutions of the fluorescent probe NP and other related analytes with a concentration of 1mM are prepared in dichloromethane. Among them, other related analytes include (COCl)2, CH3COCl, DCP (diethyl chlorophosphate), SOCl2, TsCl, POCl3, SO2Cl2 and HBr. The detection solutions for UV-visible light test and fluorescence test are obtained by diluting the above stock solutions to 10μM respectively. The fluorescent probe NP solution is mixed with a test amount of phosgene solution to detect phosgene in the solution. Similarly, in order to detect other related analytes in the solution, 30μL of the fluorescent probe NP solution is mixed with a 10-fold excess of other related analyte solutions.

[0045] Responsiveness

[0046] See also Figure 2 ,like Figure 2 As shown in Figure a, before adding phosgene, the fluorescent probe NP has a strong absorption band at 440nm; however, after adding 100μM phosgene, due to the cyclization reaction between phosgene and 1,4,7-triazine cycloalkane, the absorption band slightly shifts to 412nm, resulting in an obvious color change from light yellow to colorless in the probe NP solution. Figure 2 As shown in Figure b, before adding phosgene, the fluorescent probe NP had a weak emission peak at 507nm (quantum yield Φ = 0.03), showing weak fluorescence; however, after adding phosgene, a new strong emission band appeared at 500nm (Φ = 0.51). When exposed to a portable lamp with a wavelength of 365nm, the solution containing the fluorescent probe NP changed from weak green to obvious green, showing a significant fluorescence change. This enhanced fluorescence response may be due to the inhibition of the PET effect caused by the strong electron donation of the 4- and 7-nitrogen atoms after coupling with phosgene.

[0047] Response time

[0048] The response time of the fluorescent probe NP to phosgene was evaluated by the change trend of the fluorescence intensity of the 10 μM probe solution at 480 nm over time after the addition of phosgene. Figure 3As shown, compared with most previously reported fluorescent probes, the fluorescent probe NP responds to phosgene significantly faster and has a shorter response time. This rapid response may be due to the presence of 1,4,7-triazaheptane, which restricts the rotation of CN, thereby increasing the possibility of the probe reacting with phosgene through carbamylation. Triphosgene is a precursor of phosgene. In order to better represent the performance of the fluorescent probe NP, we also characterized triphosgene and found that triphosgene has more response times than phosgene, all of which are above 10s.

[0049] Specificity

[0050] The specificity of the fluorescent probe NP to phosgene was evaluated by titration experiments. Figure 4 The UV-visible titration spectra (a) and fluorescence titration spectra (b) of 10 μM fluorescent probe NPs after continuous addition of 0-20 μM phosgene. Due to the strong photoinduced electron transfer (PET) process, the fluorescent probe NPs initially exhibited weak fluorescence in dichloromethane. However, after the addition of phosgene, a significant fluorescence enhancement was observed at 500 nm, and the fluorescence intensity increased by 100 times. Figure 5 As shown, with the increase of phosgene content in the fluorescent probe NP, it can be observed that the fluorescence intensity is significantly increased proportionally. This content-dependent fluorescence response has a high linear relationship with a coefficient of 0.99897, indicating that there is a strong correlation between the fluorescence intensity and the phosgene concentration. In addition, the detection limit of the fluorescent probe NP is calculated by the formula LOD=3δ / k, (δ represents the standard deviation of 10 blank measurements, and k represents the slope of the fitted straight line obtained by the fluorescence titration experiment). Based on this calculation, the detection limit of the fluorescent probe NP for phosgene is 0.16nM. It can be seen that the fluorescent probe NP provided by the present invention has high sensitivity in the quantitative detection of phosgene, and has a good application prospect as a candidate material for phosgene sensing applications.

[0051] Selectivity

[0052] The selectivity of the fluorescent probe NPs towards phosgene was evaluated by selectivity experiments. Various compounds such as (COCl)2, CH3COCl, SOCl2, TsCl, DCP, POCl3, SO2Cl2 and HBr were used to evaluate the optical changes. Figure 6 As shown in the figure, under the same experimental conditions, except for DCP, only the presence of phosgene will lead to significant fluorescence enhancement. Although the fluorescence intensity also increases after the addition of DCP, the fluorescence enhancement is only one-fifth of that of phosgene, and there is also a significant difference in the peak position corresponding to the maximum fluorescence intensity. Therefore, this obvious fluorescence difference can effectively distinguish DCP from phosgene.

[0053] Interference immunity

[0054] The anti-interference test was carried out by detecting the fluorescence response of the fluorescent probe NP to phosgene in the presence of other interfering substances. Figure 7 As shown, in the presence of other interferents, the probe can still effectively enhance fluorescence, indicating that it has high selectivity for phosgene, and the probe NP can selectively distinguish phosgene from a large number of interferents and has high anti-interference ability.

[0055] stability

[0056] like Figure 8 As shown, after the fluorescent probe of the present invention is continuously excited for 72 minutes, the fluorescence intensity decays very slowly, indicating that the fluorescent probe of the present invention has good stability.

[0057] Phosgene detection in gas phase of test group 2

[0058] Preparation of phosgene detection test paper: In order to prepare the test paper for phosgene detection in the gas phase, the filter paper was first cut into strips of 1 cm x 2 cm. Subsequently, the strips were soaked in 1.0 mM fluorescent probe NP solution four times to allow the filter paper to completely adsorb the fluorescent probe NP. After each soaking, the strips were air-dried to ensure uniform and saturated adsorption. Finally, the prepared filter paper was pasted on the inner wall of a 10 mL glass bottle for the next step of phosgene detection in the gas phase.

[0059] Preparation of gas-phase phosgene: According to the established protocol described in the literature, triphosgene and triethylamine (TEA) were mixed in a sealed flask to prepare gas-phase phosgene of different concentrations. The specific operation was as follows: First, 50 μL of dichloromethane solution of triphosgene of different concentrations (0.5-10 mg / mL) was added to several sealed flasks, followed by the addition of triethylamine solution.

[0060] Phosgene in the gas phase was detected by phosgene test paper: After the phosgene test paper was incubated in different concentrations of gas phase phosgene for 5 minutes, the filter paper strip was removed from the sealed flask and irradiated with a portable 365nm UV lamp to obtain a response image for analysis. To detect other toxic analytes, including (COCl)2, CH3COCl, DCP, SOCl2, TsCl, POCl3, SO2Cl2, and HBr, the concentration of each analyte was increased to 10 times that of phosgene, and then detected according to the above steps.

[0061] Before contact with phosgene, the phosgene test paper is light yellow and has no fluorescence under 365nm excitation. Fig. 9As shown in the figure, after being exposed to gas-phase phosgene at a concentration of 1 to 50 ppm for 1 minute, the phosgene detection test paper exhibits green fluorescence under 365 nm ultraviolet light excitation. It is worth noting that even after being exposed to 1 ppm of gas-phase phosgene, the probe-loaded test paper still exhibits obvious fluorescence changes, indicating that these probes loaded on the test paper can meet the visual detection requirements of phosgene within a safe range.

[0062] like Fig.10 As shown, the selectivity of the fluorescent probe NP for phosgene was verified by exposing the probe-loaded test paper to other interfering substances for the same period of time. The results showed that, except for DCP, no fluorescence changes occurred after exposure to other interfering substances, which was consistent with the previous results.

[0063] In order to further demonstrate the advantages of the fluorescent probe of the present invention, the performances of the fluorescent probe of the present invention and the reported phosgene fluorescent probes are summarized in Table 1.

[0064] Table 1

[0065]

[0066]

[0067] It can be seen from Table 1 that the fluorescent probe of the present invention has the advantages of a large linear range, a short response time and a lower detection limit compared with the fluorescent probe disclosed in the prior art.

[0068] 1.Tan J, Li Z, Yao W, Ji Z, Sun Z, You J. Construction of ultrasensitive devices for visualization and quantification of phosgene based on FRET-mediated twophoton chemosensor. Dyes Pigments 2021;187:109138.

[0069] 2.Y.Hu,L.Chen,H.Jung,Y.Zeng,S.Lee,KM.K.Swamy,et al.,Effectivestrategy for colorimetric and fluorescence sensing of phosgene based on smallorganic dyes and nanofiber platforms,ACS Appl..Mater.Interfaces,2016,8,22246-22252.

[0070] 3. Zhang Y, Qiu X, Wang B, Liu

[0071] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A fluorescent probe (NP) based on naphthalimide-1,4,7-triazaheptane, characterized in that: The chemical structure is as follows:

2. A method for preparing a fluorescent probe based on naphthalimide-1,4,7-triazaheptane as claimed in claim 1, characterized in that: The following steps are involved: Compound 1 is reacted with compound 2 in a solvent to obtain a fluorescent probe based on naphthalimide-1,4,7-triazaheptane; the specific reaction formula is as follows:

3. The method for preparing a fluorescent probe based on naphthalimide-1,4,7-triazaheptane according to claim 2, characterized in that: The molar ratio of the compound 1 to the compound 2 is 1:(0.1-10); the dosage ratio of the compound 1 to the solvent is 1 g:(50-200) mL.

4. The method for preparing a fluorescent probe based on naphthalimide-1,4,7-triazaheptane according to claim 2, characterized in that: The solvent is methoxyethanol.

5. The method for preparing a fluorescent probe based on naphthalimide-1,4,7-triazaheptane according to claim 2, characterized in that: The reaction temperature is 100-140°C, and the reaction time is 8-24h.

6. Use of the fluorescent probe based on naphthylimide-1,4,7-triazaheptane as claimed in claim 1 in phosgene detection.

7. The use of the fluorescent probe based on naphthalimide-1,4,7-triazaheptane in phosgene detection according to claim 6, characterized in that: The phosgene detection includes phosgene detection in solution or phosgene detection in gas phase.

8. The use of the fluorescent probe based on naphthalimide-1,4,7-triazaheptane in phosgene detection according to claim 6, characterized in that: The phosgene detection is a qualitative detection or a quantitative detection.

9. The use of the fluorescent probe based on naphthalimide-1,4,7-triazaheptane in phosgene detection according to claim 8, characterized in that: The linear range of the quantitative detection is 0-10 μM.

10. The use of the fluorescent probe based on naphthalimide-1,4,7-triazaheptane in phosgene detection according to claim 8, characterized in that: The qualitative detection is achieved by preparing a phosgene detection test paper based on a fluorescent probe based on naphthalimide-1,4,7-triazaheptane.

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