Tanshinone benzimidazole-type fluorescent probe for detecting hydrazine and preparation method thereof

Abstract

The invention discloses a tanshinone benzimidazole-type fluorescent probe for detecting hydrazine and a preparation method thereof. Tanshinone IIA is directly subjected to a condensation reaction with terephthalaldehyde and ammonium acetate to prepare 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furano[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde, which is then reacted with ethyl cyanoacetate to synthesize ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furano[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate. The compound can selectively react with hydrazine, and after the reaction, orange-red fluorescence is converted to blue fluorescence. The compound can be used as a fluorescent probe for detecting hydrazine.

Description

Technical Field

[0001] The invention belongs to the field of fine organic synthesis, and particularly relates to a tanshinone benzimidazole-type fluorescent probe for detecting hydrazine and a preparation method thereof. Background Art

[0002] Hydrazine (N2H4) is not only a well-known corrosion inhibitor but also a rocket propellant due to its high combustion enthalpy. However, due to its widespread use in manufacturing, transportation, handling, and use, hydrazine can cause serious environmental pollution, posing a significant threat to public health and the ecological environment. Hydrazine has been designated as a possible carcinogen by the U.S. Environmental Protection Agency, and long-term exposure to high concentrations of hydrazine and its substituted derivatives can cause irreparable damage to the central nervous system. Given this, there is an urgent need to establish simple and sensitive analytical methods for identifying hydrazine in the environment.

[0003] Therefore, developing a suitable method for the specific qualitative and quantitative detection of hydrazine is of particular importance. Traditionally, electrochemical analysis, colorimetry, spectrophotometry, titration, and high-performance liquid chromatography (HPLC) have been used for the detection of hydrazine. Unfortunately, most of these methods are costly, time-consuming, and difficult to operate, making them inconvenient for real-time and in situ monitoring. In contrast, fluorescent probe detection methods offer the advantages of ultrasensitivity, good selectivity, and simplicity of operation, making them suitable for monitoring hydrazine both in vitro and in vivo.

[0004] Danshen (Salvia miltiorrhiza) is one of the most important herbs in Traditional Chinese Medicine (TCM), developed into over thirty pharmaceutical formulations. Tanshinone IIA is a major component of Danshen (Salvia miltiorrhiza). Tanshinone IIA is a lipophilic component that accounts for at least 9.8% of all components in Danshen and regulates a range of physiological processes, including inflammation, oxidative stress, and apoptosis.

[0005] Currently, many natural organic compounds have been modified into fluorescent probes to detect different compounds or ions, such as coumarin fluorescent probes, flavonoid fluorescent probes, and cellulose fluorescent probes. However, no research has been published on the use of tanshinone benzimidazole-type fluorescent probes to detect hydrazine. Summary of the Invention

[0006] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0007] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0008] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a tanshinone benzimidazole-based fluorescent probe for detecting hydrazine.

[0009] To solve the above technical problems, the present invention provides the following technical solution: a tanshinone benzimidazole-type fluorescent probe for detecting hydrazine, the name of the fluorescent probe is: ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate, and its structural formula is:

[0010]

[0011] Another object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing a tanshinone benzimidazole-type fluorescent probe, comprising:

[0012] Tanshinone IIA was condensed with terephthalaldehyde to prepare 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde;

[0013] 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furan[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde is reacted with ethyl cyanoacetate to synthesize ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furan[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate to obtain the fluorescent probe.

[0014] As a preferred embodiment of the preparation method of the present invention, the preparation method of the 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furan[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde comprises:

[0015] Terephthalaldehyde and tanshinone IIA were dissolved in acetic acid, and then an ammonium acetate solution dissolved in acetic acid was slowly added. After the reaction was completed, a saturated sodium bicarbonate aqueous solution was added to precipitate a solid, which was filtered and purified by column chromatography to obtain yellow 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde.

[0016] As a preferred embodiment of the preparation method of the present invention, the molar ratio of tanshinone IIA, terephthalaldehyde and ammonium acetate is 1:3:7.

[0017] As a preferred embodiment of the preparation method of the present invention, the reaction temperature is 125° C. and the reaction time is 50 minutes.

[0018] As a preferred embodiment of the preparation method of the present invention, the preparation method of ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furan[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate comprises:

[0019] 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde was dissolved in anhydrous ethanol, and ethyl cyanoacetate was added dropwise, followed by 5 drops of piperidine. The mixture was stirred and refluxed for 12 h under nitrogen protection.

[0020] The crude product was cooled to room temperature, dried under vacuum, and purified by column chromatography to obtain brown-red ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate.

[0021] As a preferred embodiment of the preparation method of the present invention, the molar mass ratio of the 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furan[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde to ethyl cyanoacetate is 1:1.1.

[0022] As a preferred embodiment of the preparation method of the present invention, the reaction temperature is 80° C. and the reaction time is 10 to 12 hours.

[0023] Another object of the present invention is to overcome the deficiencies in the prior art and provide a tanshinone benzimidazole fluorescent probe for use in detecting hydrazine, wherein the concentration of the hydrazine is 0 to 80 μM.

[0024] Beneficial effects of the present invention:

[0025] The present invention uses the natural product tanshinone IIA with excellent fluorescence properties as a raw material to prepare ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate (TPE). Compared with the previous tanshinone IIA, the ketone carbonyl group is modified to effectively improve the water solubility of the compound. The introduction of benzimidazolyl and ethyl cyanoacetate groups further improves the fluorescence properties of the molecule. The compound can selectively react with hydrazine to convert orange-red fluorescence into blue fluorescence. The compound can be used as a fluorescent probe for detecting hydrazine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0027] Figure 1 This is a fluorescence emission spectrum effect diagram of ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate in Example 2 of the present invention interacting with different substances.

[0028] Figure 2 This is a fluorescence emission spectrum effect diagram of the reaction of ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate with different concentrations of hydrazine in Example 3 of the present invention.

[0029] Figure 3 The fluorescence effect diagram of ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate with hydrazine and different interfering substances under 365nm ultraviolet light.

[0030] Figure 4 This is a fluorescence emission spectrum effect diagram of ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate in Example 4 of the present invention after reacting with hydrazine and interacting with different substances. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0032] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0033] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0034] Example 1

[0035] The synthesis method of tanshinone benzimidazole compounds comprises the following steps:

[0036]

[0037] The specific steps are as follows:

[0038] (1) Preparation of 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde:

[0039] Accurately weigh 210 mg of terephthalaldehyde and 346 mg of ammonium acetate, add them to a three-necked flask, then add 4 ml of acetic acid and stir to dissolve. Accurately weigh 147 mg of tanshinone IIA, add 4 mL of acetic acid to dissolve it, and then add it to a dropping funnel. Use a dropping funnel to slowly add the acetic acid solution of tanshinone IIA dropwise into the three-necked flask. React at 125°C for 50 minutes, add saturated sodium bicarbonate aqueous solution to neutralize it, precipitate the solid, filter it with suction, and purify it through a column (petroleum ether: ethyl acetate = 300:1 to 5:1) to obtain a yellow solid compound 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde with a yield of 75%.

[0040] (2) Preparation of ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate (TPE):

[0041] 408 mg of 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde obtained in the previous step was accurately weighed and dissolved in 20 mL of ethanol. Subsequently, 113 mg of ethyl cyanoacetate was added, and 5 drops of piperidine were added. The mixture was stirred and refluxed at 80°C for 12 h. The crude product was cooled to room temperature, dried under vacuum, and purified by column chromatography (petroleum ether:ethyl acetate = 50:1 to 5:1) to obtain pure brown-red ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate in a yield of 88%.

[0042] Product characterization data are:

[0043] 1 H NMR (600MHz, DMSO-d6) δ13.05 (s, 1H), 8.52 (d, J = 8.3Hz, 1H), 8.38 (s, 1H), 8. 19(d,J=8.4Hz,2H),8.15(d,J=8.4Hz,1H),8.08(d,J=8.6Hz,1H),7.89(s,1H ),7.64(d,J=8.6Hz,1H),4.36–4.31(m,2H),3.94(t,J=6.3Hz,2H),2.61(s,3 H),1.99–1.95(m,2H),1.78–1.74(m,2H),1.38(s,6H),1.34(d,J=7.1Hz,3H). 13 C NMR(151MHz,DMSO-d6)δ162.38,154.56,149.81,146.11,145.97,143.40,141.77,137.40,135.23,133.44,131.71,131.54,127.27,126.6 6,124.61,123.00,118.26,117.82,116.26,115.86,112.14,102.39,62.81,38.94,34.80,32.40,31.27,20.07,14.49,10.26.ESI-MS:m / z calculated for C 32 H 29 N3O3[M+H] + 504.2287,found504.2294.

[0044] Example 2

[0045] Accurately weigh 5 mg of fluorescent probe TPE and dissolve it in tetrahydrofuran to prepare 1×10 -3 M solution, take 100 μM stock solution and dilute it with tetrahydrofuran aqueous solution (tetrahydrofuran: water = 4:6) to 10 mL with a concentration of 1×10 -5 M solution, and then add equimolar amounts of N2H4, Ca 2+ 、Al 3+ 、Zn 2+ 、Cu 2+ 、Hg 2+ 、Fe 2+ 、Fe 3+ 、NO 2- 、CO3 2- 、CH3COO - 、HSO3 - 、H2PO4 - 、Cl - , H2O2, Cys, GSH, glycine, urea, Ala, aniline, diethylamine, cyclohexylamine, phenylhydrazine, pentafluorophenylhydrazine and other analytes, and record the fluorescence spectrum of the solution.

[0046] like Figure 1 As shown, where 1 represents Ca2+, 2 represents Al3+, 3 represents Zn2+, 4 represents Cu2+, 5 represents Hg2+, 6 represents Fe2+, 7 represents Fe3+, 8 represents NO2-, 9 represents CO32-, 10 represents CH3COO-, 11 represents HSO3-, 12 represents H2PO4-, 13 represents Cl-, 14 represents H2O2, 15 represents Cys, 16 represents GSH, 17 represents glycine, 18 represents urea, 19 represents Ala, 20 represents aniline, 21 represents diethylamine, 22 represents cyclohexylamine, 23 represents phenylhydrazine, and 24 represents pentafluorophenylhydrazine;

[0047] It can be seen that after the addition of hydrazine, the solution shows a very obvious change from orange-red fluorescence to blue fluorescence. When other analytes are added, the fluorescence intensity and wavelength of the fluorescent probe TPE do not change much, indicating that this compound has excellent selectivity as a fluorescence ratio probe for detecting hydrazine.

[0048] Example 3

[0049] The fluorescent probe TPE was dissolved in tetrahydrofuran aqueous solution (tetrahydrofuran: water = 4:6) (1×10 -5 M), add (0~80)×10 -5 M of hydrazine, and measured the fluorescence emission spectra of ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate with different concentrations of hydrazine added;

[0050] like Figure 2 The fluorescence emission spectra of the compound in the presence of varying concentrations of hydrazine are shown in Figure 2. The compound's fluorescence gradually shifts to a blue color with the addition of hydrazine, indicating that the compound reacts with hydrazine. The intensity ratio (F469 nm / F630 nm) of the TPE probe exhibits a good linear relationship with hydrazine concentration from 0 to 80 μM (y = 0.059x + 0.133, R² = 0.99597). The limit of detection (LOD) calculated using the 3δ / K method is as low as 58 nM.

[0051] Example 4

[0052] Accurately weigh 5 mg of fluorescent probe TPE and dissolve it in tetrahydrofuran to prepare 1×10 -3 M solution, take 100 μM stock solution and dilute it with tetrahydrofuran aqueous solution (tetrahydrofuran: water = 4:6) to 10 mL with a concentration of 1×10 -5 M solution, add 80 μL of hydrazine (1×10 -2 M), observed under 365nm ultraviolet light, as Figure 3 As shown, the fluorescence of the solution to which hydrazine was added changed from orange-red to blue, indicating that the compound could react with hydrazine. Under a 365 nm ultraviolet lamp, the blue fluorescence was enhanced, and hydrazine was detected.

[0053] However, the addition of equimolar amounts of Ca2+, Al3+, Zn2+, Cu2+, Hg2+, Fe2+, Fe3+, NO2-, CO32-, CH3COO-, HSO3-, H2PO4-, Cl-, H2O2, Cys, GSH, glycine, urea, Ala, aniline, diethylamine, cyclohexylamine, phenylhydrazine, and pentafluorophenylhydrazine did not result in a change in the compound's fluorescence, indicating that the compound can be used as an effective fluorescent probe for the identification of hydrazine.

[0054] Example 5

[0055] In the fluorescent probe TPE (1×10 -5 M) and hydrazine (80×10 -5 Interference experiments were conducted by adding equimolar amounts of other ions, including Ca2+, Al3+, Zn2+, Cu2+, Hg2+, Fe2+, Fe3+, NO2-, CO32-, CH3COO-, HSO3-, H2PO4-, Cl-, H2O2, Cys, GSH, glycine, urea, Ala, aniline, diethylamine, cyclohexylamine, phenylhydrazine, and pentafluorophenylhydrazine, to the fluorescence system (M). Changes in the fluorescence intensity ratio (F469nm / F630nm) were recorded using a fluorescence spectrophotometer.

[0056] like Figure 4As shown, 1 represents Ca2+, 2 represents Al3+, 3 represents Zn2+, 4 represents Cu2+, 5 represents Hg2+, 6 represents Fe2+, 7 represents Fe3+, 8 represents NO2-, 9 represents CO32-, 10 represents CH3COO-, 11 represents HSO3-, 12 represents H2PO4-, 13 represents Cl-, 14 represents H2O2, 15 represents Cys, 16 represents GSH, 17 represents glycine, 18 represents urea, 19 represents Ala, 20 represents aniline, 21 represents diethylamine, 22 represents cyclohexylamine, 23 represents phenylhydrazine, and 24 represents pentafluorophenylhydrazine. After adding other ions, the fluorescence intensity ratio of the above fluorescence system does not change much and remains in a blue-shifted state. Therefore, this compound has good anti-interference ability when detecting hydrazine. This shows that this compound is a highly specific fluorescent probe for detecting hydrazine.

[0057] Example 6

[0058] Optimization of the preparation method of ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2',3':1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate:

[0059] Experiment 1: 408 mg of 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde was accurately weighed and dissolved in 20 mL of ethanol. 113 mg of ethyl cyanoacetate was then added, and 5 drops of piperidine were added. The mixture was stirred and refluxed at 80°C for 2 h. The crude product was cooled to room temperature, dried under vacuum, and purified by column chromatography (petroleum ether:ethyl acetate = 50:1 to 5:1) to obtain pure brown-red ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate with a yield of 45%.

[0060] Experiment 2: Accurately weigh 408 mg of 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde and dissolve it in 20 mL of methanol. Then add 113 mg of ethyl cyanoacetate and 0.1 mL of triethylamine. Stir and reflux at 80°C for 12 h. After cooling the crude product to room temperature, vacuum dry it and purify it by column chromatography (petroleum ether:ethyl acetate=50:1~5:1) to obtain pure brown-red ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate with a yield of 10%.

[0061] Experiment 3: Accurately weigh 408 mg of 4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)benzaldehyde and dissolve it in 20 mL of methanol. Then add 113 mg of ethyl cyanoacetate and drop 5 drops of piperidine. Stir and reflux at 80°C for 12 h. After cooling the crude product to room temperature, vacuum dry it and purify it by column chromatography (petroleum ether:ethyl acetate = 50:1 to 5:1) to obtain pure brown-red ethyl (E)-2-cyano-3-(4-(1,6,6-trimethyl-7,8,9,12-tetrahydro-6H-furo[2′,3′:1,2]phenanthro[3,4-d]imidazol-11-yl)phenyl)acrylate with a yield of 88%.

[0062] Table 1

[0063]

[0064] As can be seen from Table 1, the reaction time of the conditions of Experiment 3 is the fastest and the yield is the highest compared with other reaction conditions, so this condition is selected for the reaction.

[0065] Example 7

[0066] Hydrazine is a water-soluble suspected carcinogen that poses a threat to human health. Therefore, the fluorescent probe TPE was used to detect hydrazine in environmental water samples. Environmental water samples (Xuanwu Lake, Yangtze River, and tap water) were pretreated to prepare sample solutions. Then, the fluorescent probe TPE (10 μM) and varying concentrations of hydrazine (0 to 40 μM) were added, and the fluorescence intensity ratio (F469 nm / F630 nm) of each sample was recorded.

[0067] See Table 2.

[0068] Table 2 Results of fluorescent probe TPE detection of different concentrations of hydrazine in water samples

[0069]

[0070] As can be seen from Table 2, the experiment showed good recovery rates in all water samples. The results show that the fluorescent probe TPE can effectively track the presence of hydrazine in real environmental water samples.

[0071] The present invention aims to provide a tanshinone benzimidazole-based fluorescent probe for detecting hydrazine. The probe reacts with hydrazine and converts its orange-red fluorescence to blue fluorescence under 365nm ultraviolet light, making it suitable for detecting hydrazine. The probe is prepared using tanshinone IIA, a natural molecule with excellent fluorescent activity, through a two-step chemical reaction. The broad availability of raw materials and the minimal number of reaction steps pave the way for large-scale production. The compound selectively reacts with hydrazine, converting its orange-red fluorescence to blue fluorescence, making it suitable for use as a fluorescent probe for detecting hydrazine.

[0072] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the present invention.

Claims

1. A tanshinone benzimidazole-based fluorescent probe for detecting hydrazine, characterized in that: The structural formula of the fluorescent probe is:

2. The method for preparing the tanshinone benzimidazole-based fluorescent probe according to claim 1, wherein: include, Tanshinone IIA is condensed with terephthalaldehyde to prepare the compound shown in the following formula I: The compound represented by Formula I is reacted with ethyl cyanoacetate to synthesize a fluorescent probe, the structural formula of which is:

3. The preparation method according to claim 2, characterized in that: The preparation method of the compound represented by formula I comprises: Terephthalaldehyde and tanshinone IIA were dissolved in acetic acid, and then ammonium acetate solution dissolved in acetic acid was slowly added. After the reaction was completed, saturated sodium bicarbonate aqueous solution was added to precipitate solids, which were filtered and purified by column chromatography to obtain a yellow compound represented by formula I.

4. The preparation method according to claim 3, wherein: The molar ratio of tanshinone IIA, terephthalaldehyde and ammonium acetate is 1:3:

7.

5. The preparation method according to claim 3 or 4, characterized in that: The reaction temperature is 125° C. and the reaction time is 50 minutes.

6. The preparation method according to claim 2, characterized in that: The preparation method of the fluorescent probe comprises: The compound represented by formula I was dissolved in anhydrous ethanol, and ethyl cyanoacetate was added dropwise, followed by 5 drops of piperidine. The mixture was stirred and refluxed for 12 hours under nitrogen protection. The crude product was cooled to room temperature, dried under vacuum, and purified by column chromatography to obtain a brown-red fluorescent probe.

7. The preparation method according to claim 6, characterized in that: The molar mass ratio of the compound represented by formula I to ethyl cyanoacetate is 1:1.

1.

8. The preparation method according to claim 6, characterized in that: The reaction temperature is 80° C., and the reaction time is 10 to 12 hours.

9. Use of the tanshinone benzimidazole-based fluorescent probe according to claim 1 in detecting hydrazine.

10. The use according to claim 9, characterized in that: The concentration of the hydrazine is 0-80 μM.

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