A preparation method and application of a compound based on Rhodol structure

Abstract

The present invention discloses a preparation method and application of a compound based on a Rhodol structure. The structural formula of the compound is as follows: #imgabs0# The compound based on the Rhodol structure is used to prepare a fluorescent probe, which can quickly detect Ba 2+ , right 2+ It has the advantages of high sensitivity, high selectivity and short response time. It can also be used in water quality testing. By observing the change in the fluorescence emission spectrum intensity ΔF of the fluorescent probe before and after adding the water sample to be tested, the barium ions in drinking water can be detected.

Description

Technical Field

[0001] The invention belongs to the technical field of organic compound synthesis and fluorescence detection, and specifically relates to a preparation method and application of a compound based on a Rhodol structure. Background Art

[0002] Barium is a soft alkaline earth metal with a silvery white luster. Due to its very active chemical properties, barium has not yet been found in nature. The most common minerals of barium in nature are barite (barium sulfate) and barite (barium carbonate). The content of barium in soil is about 500 mg / kg, and the content in surface water and seawater is about 0.01 mg / L and 0.013 mg / L respectively. However, with the application of barium in industry, such as pigments, steel quenching, ceramics and glass industries, it is inevitable that some barium compounds will enter the groundwater with waste and wastewater, causing water pollution. The "Sanitary Standard for Drinking Water" (GB 5749-2006) jointly issued by the National Standards Committee and the Ministry of Health has made relevant regulations on the content of barium ions in drinking water, that is, the maximum allowable content of barium ions in drinking water as a non-conventional toxicological indicator is 0.7 mg / L. If barium ions accumulate in large quantities in the human body, it can cause acute poisoning, and symptoms such as gastrointestinal irritation, hypokalemia, chest tightness, and palpitations will appear.

[0003] At present, the analysis methods of metal ions such as barium ions mainly use absorption / emission spectroscopy, ion chromatography, inductively coupled plasma atomic emission spectroscopy and inductively coupled plasma mass spectrometry. These methods have high accuracy and sensitivity, but require strong technical expertise and high cost. Therefore, efficient and rapid detection of metal ions is of great significance in medicine, biology and environmental science. Among them, organic small molecule fluorescent probes have some more significant advantages, such as: high sensitivity, good fluorescence reproducibility, membrane permeability, simple operation, good in situ properties, etc.

[0004] Therefore, it is necessary to design a simple, sensitive and rapid fluorescent probe for detecting barium ions in water samples. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a compound based on a Rhodol structure in view of the problems existing in the prior art; the compound can be used as a fluorescent probe for detecting barium ions in water samples, and has the advantages of high sensitivity, high selectivity, short synthesis steps, simple conditions, etc., and has good application prospects and value.

[0006] In order to achieve the above invention object, the specific technical scheme of the present invention is as follows:

[0007] The first invention objective of the present invention is to protect a compound based on a Rhodol structure, the structure of which is shown in formula (III):

[0008]

[0009] (III).

[0010] The second invention objective of the present invention is to protect a method for preparing a compound based on a Rhodol structure, the reaction route of the compound is:

[0011] .

[0012] As a preferred embodiment of the present application, the method for preparing the above-mentioned Rhodol structure-based compound comprises the following steps:

[0013] 1) dissolving benzoic anhydride in toluene; then adding m-hydroxy-N,N-diethylaniline to the above system, and continuing the reaction after heating; after the reaction is completed, evaporating the solvent, recrystallizing with n-butanol, and then purifying to obtain intermediate product I;

[0014] 2) Dissolve the intermediate product I and resorcinol in trifluoroacetic acid, and then perform a reflux reaction; after the reaction is completed, evaporate the solvent, recrystallize with ethyl acetate, and then purify to obtain the intermediate II;

[0015] 3) Dissolve intermediate II and 5-chloro-8-hydroxyquinoline in dichloromethane; then add DMAP and DCC, and react at room temperature overnight; after the reaction is complete, evaporate and remove the solvent;

[0016] 4) Using dichloromethane and methanol as eluents, column chromatography was performed to purify the product to obtain a red solid, namely, compound III based on the Rhodol structure.

[0017] As a preferred embodiment of the present application, the solvent in step 1) is toluene; the molar ratio of m-hydroxy-N,N-diethylaniline to benzoic anhydride is 1:1-1:5 (preferably 1:1); the reaction temperature in step 1) is 80-110°C (preferably 110°C), and the reaction time is 8-14 h (preferably 12 h); the temperature at which benzoic anhydride is dissolved in toluene is 70°C-90°C (preferably 80°C), and the dissolution time is 10 to 30 minutes (preferably 30 minutes).

[0018] As a preferred embodiment of the present application, the solvent in step 2) is trifluoroacetic acid; the molar ratio of the intermediate product I to resorcinol is 1:1; the temperature of the reflux reaction is 75°C-100°C (preferably 90°C), and the reaction time is 8-16 h (preferably 12 h).

[0019] As a preferred embodiment of the present application, the solvent in step 3) is dichloromethane; the molar ratio of intermediate II and 5-chloro-8-hydroxyquinoline, DMAP (4-dimethylaminopyridine) and DCC (dicyclohexylcarbodiimide) is 1:1:1:2; the ratio of the volume mL of dichloromethane to the mass g of the intermediate II compound is 10:1; and the reaction time at room temperature overnight is 12 hours.

[0020] The third object of the present invention is to provide a fluorescent probe, which contains the aforementioned Rhodol structure-based compound (or the compound of formula (III)), or contains the Rhodol structure-based compound (or the compound of formula (III)) prepared by any of the aforementioned methods.

[0021] The fourth invention objective of the present invention is to protect the use of the fluorescent probe described above in detecting barium ions.

[0022] The fifth invention objective of the present invention is to protect a method for detecting barium ions in water samples using the fluorescent probe described above, the method comprising the following steps: using a reagent containing a fluorescent probe as a fluorescent reagent; adding a water sample to be tested containing barium ions to the fluorescent reagent, and then exciting it with a fixed excitation wavelength, observing the change in the intensity of the fluorescence emission spectrum before and after adding the water sample to be tested, that is, detecting the barium ions in the water sample.

[0023] As a preferred embodiment of the present application, the method for detecting barium ions in water samples using a fluorescent probe comprises the following steps:

[0024] (1) Prepare the fluorescent probe solution: weigh the compound based on the Rhodol structure and dissolve it in acetonitrile solution to obtain the standard solution of the fluorescent probe;

[0025] (2) Determination of fluorescence spectrum: Add the water sample to be tested into the fluorescent probe, measure the fluorescence emission spectrum with a fixed excitation wavelength of 290 nm, and draw a curve of the change of fluorescence intensity at the excited wavelength;

[0026] (3) Fluorescence spectrum analysis: Calculate the intensity change △F of the fluorescence emission spectrum at 580 nm before and after adding the water sample to the fluorescent probe solution, that is, detect the barium ions in the water sample.

[0027] As a preferred embodiment of the present application, in step 1) of the method for detecting barium ions in water samples using a fluorescent probe, the ratio of the mass mg of the compound based on the Rhodol structure to the volume mL of acetonitrile is 13.7:25; the pH value of the standard solution is 7.4; the molar concentration of the standard solution is 1.0×10 -3 mol / L.

[0028] More specific steps are:

[0029] (1) Preparation of fluorescent probe: Weigh 13.7 mg of the compound of formula (III), dissolve it in acetonitrile to a volume of 25 mL, pH = 7.4, and a standard solution of the fluorescent probe is obtained;

[0030] (2) Fluorescence spectrum measurement: Add the water sample to be tested to the fluorescent probe solution, and then dilute it with acetonitrile at pH = 7.4. After standing for 5 minutes, perform fluorescence emission spectrum measurement at a fixed excitation wavelength of 290 nm, and draw a curve of the fluorescence intensity change at the excited wavelength;

[0031] (3) Fluorescence spectrum analysis: The change in fluorescence emission spectrum intensity at 580 nm before and after the fluorescent probe solution is added to the water sample is calculated, and the barium ions in the water sample can be detected.

[0032] As a better embodiment of the present application, in the method of detecting barium ions in water samples using a fluorescent probe, the method of fluorescence spectral analysis described in step 3) is specifically as follows: when the fluorescence emission spectrum intensity change △F corresponding to 580 nm before and after the fluorescent probe solution is added to the water sample to be tested is large, it indicates that the water sample to be tested contains barium ions; when the fluorescence emission spectrum intensity change △F corresponding to 580 nm before and after the fluorescent probe solution is added to the water sample to be tested is small, it indicates that the water sample to be tested does not contain barium ions.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (I) The present invention provides a fluorescent probe based on the Rhodol structure for detecting Ba 2+ It has the advantages of high sensitivity, high selectivity, low test cost, simple operation, etc., and has strong scientific research significance and practical application value.

[0035] (II) The fluorescent probe of the present invention is Ba 2+ It has high selectivity, sensitivity and low detection limit. When the fluorescent probe exists alone, the excitation wavelength is fixed at 290 nm, and the excitation / emission gap is 1 / 2.5 nm, the fluorescence intensity value at the fluorescence emission wavelength of 580 nm is weak. 2+ No fluorescence spectral properties, when Ba is added to the probe 2+ After the solution was prepared, the fluorescence intensity at 580 nm of the fluorescence emission spectrum was significantly enhanced. The present invention also conducted an anti-interference experiment, which showed that the fluorescent probe had high selectivity.

[0036] (III) Ba provided by the present invention 2+The detection method is faster, simpler and more sensitive than traditional detection technologies such as inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a fluorescence emission spectrum of the fluorescent probe prepared in Example 1 of the present invention, wherein the abscissa is the wavelength (nm) and the ordinate is the fluorescence emission intensity;

[0038] Figure 2 The ultraviolet absorption spectrum of the fluorescent probe prepared in Example 1 of the present invention, wherein the abscissa is the wavelength (nm) and the ordinate is the ultraviolet absorption intensity;

[0039] Figure 3 This is a diagram showing the selective determination of various metals by the fluorescent probe prepared in Example 1 of the present invention. The metal ions detected are: Ba 2+ , Cu 2+ 、Ni 2+ 、Al 3+ , Mn 2+ Mg 2+ 、Cd 2+ 、Co 2+ , Ca 2+ 、Na + , Fe 3+ , Fe 2+ ;

[0040] Figure 4 The fluorescent probe Ba prepared in Example 1 of the present invention 2+ Fluorescence titration, where the horizontal axis is wavelength (nm), the vertical axis is fluorescence emission intensity, and the drawing of the standard curve. DETAILED DESCRIPTION

[0041] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0042] Any feature disclosed in this specification (including claims and abstract), unless otherwise stated, may be replaced by other alternative features that are equivalent or have similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0043] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0044] In this application, the compound based on the Rhodol structure has the molecular formula C 33 H 25 ClN2O5, molecular weight is 549.02.

[0045] Embodiment 1:

[0046] A method for preparing a compound based on a Rhodol structure, wherein the reaction route of the compound is:

[0047] .

[0048] The preparation steps are:

[0049] Weigh m-hydroxy-N,N-diethylaniline (1.65 g) and benzoic anhydride (1.48 g); first dissolve benzoic anhydride in 15 mL toluene and react at 80 °C for 30 minutes; after 30 minutes, add m-hydroxy-N,N-dimethylaniline to the system, raise the temperature to 110 °C, and continue to react for 8 hours. TLC detection reaction, the reaction is complete, the solvent is removed by rotary evaporation, and then recrystallized with n-butanol and purified by column chromatography to obtain intermediate product I (yield 86%).

[0050] Weigh the intermediate product I (1.56 g) and resorcinol (0.55 g), dissolve in 5 mL of trifluoroacetic acid, and reflux at 80 °C for 12 h. The reaction is detected by TLC and the reaction is complete. The solvent is removed by rotary evaporation. Then recrystallization is performed with ethyl acetate and column chromatography is used to purify the compound to obtain intermediate II (yield is 80%).

[0051] Take intermediate II (387.44 mg) and 5-chloro-8-hydroxyquinoline (283.07 mg), dissolve in 5 mL of dichloromethane, then add DMAP (122.17 mg) and DCC (412.66 mg), and react at room temperature overnight. TLC detects the reaction, and after the reaction is complete, the solvent is removed by rotary evaporation. Then dichloromethane and methanol are used as eluents, and the volume ratio of dichloromethane to methanol is 20:1; column chromatography purification obtains a red solid product, that is, the final product is a compound based on the Rhodol structure (yield is 76%).

[0052] Product NMR and mass spectrometry characterization:

[0053] 1 H NMR (600 MHz, DMSO- d 6) δ 8.81 (d, J = 4.0 Hz, 1H), 8.55 (dd, J = 17.0,8.2 Hz, 2H), 7.98 (t, J = 7.5 Hz, 1H), 7.90 (t, J = 7.6 Hz, 1H), 7.77 (d, J= 8.2Hz, 1H), 7.69 (dd, J = 8.6, 4.2 Hz, 1H), 7.58 (d, J = 7.5 Hz, 1H), 7.42 (d, J = 8.2Hz, 1H), 6.87 (dd, J = 15.8, 9.4 Hz, 2H), 6.78 (dd, J = 9.3, 2.5 Hz, 1H), 6.68(d, J = 2.5 Hz, 1H), 6.37 (dd, J = 9.6, 1.7 Hz, 1H), 6.11 (d, J = 1.8 Hz, 1H), 3.47(q, J = 6.9 Hz, 4H), 1.12 (t, J = 7.0 Hz, 6H). 13 C NMR (151 MHz, Chloroform- d ) δ185.06, 164.11, 159.16, 155.53, 152.20, 150.94, 150.85, 146.19,141.29, 133.04, 132.92, 131.66, 130.72 , 130.47 , 129.75 , 129.68 ,129.59 , 129.00 , 127.78 , 127.24 , 125.89 , 122.55 , 120.97 , 115.09 ,109.92 , 105.13 , 96.57 , 45.05 , 12.55 .ESI-MS m / z calcd for C 33 H 25 ClN2O5[M+H] + 550.03 , found 550.60 .

[0054] Embodiment 2:

[0055] A method for preparing a compound based on a Rhodol structure, wherein the reaction route of the compound is:

[0056] .

[0057] The preparation steps are:

[0058] Weigh m-hydroxy-N,N-diethylaniline (1.65 g) and benzoic anhydride (1.48 g); first dissolve benzoic anhydride in 15 mL toluene and react at 80 °C for 30 minutes; after 30 minutes, add m-hydroxy-N,N-dimethylaniline to the system, raise the temperature to 100 °C, and continue to react for 12 h. TLC detection reaction, the reaction is complete, the solvent is removed by rotary evaporation, and then recrystallized with n-butanol and purified by column chromatography to obtain intermediate product I (yield 86%).

[0059] Weigh the intermediate product I (1.56 g) and resorcinol (0.55 g), dissolve in 5 mL of trifluoroacetic acid, and reflux at 90 °C for 8 h. The reaction is detected by TLC and the reaction is complete. The solvent is removed by rotary evaporation. Then recrystallization is performed with ethyl acetate and the compound is purified by column chromatography to obtain the intermediate II (yield is 74%).

[0060] Take intermediate II (387.44 mg) and 5-chloro-8-hydroxyquinoline (283.07 mg), dissolve in 5 mL of dichloromethane, then add DMAP (122.17 mg) and DCC (412.66 mg), and react at 40 °C for 12 h. TLC detection reaction, after the reaction is complete, the solvent is removed by rotary evaporation. Then, dichloromethane and methanol are used as eluents in a volume ratio of 20 to 1, and column chromatography is used for purification to obtain a red solid product, that is, the final product is a compound based on the Rhodol structure (yield is 81%).

[0061] Embodiment 3:

[0062] A method for preparing a compound based on a Rhodol structure, wherein the reaction route of the compound is:

[0063] .

[0064] The preparation steps are:

[0065] Weigh m-hydroxy-N,N-diethylaniline (1.65 g) and benzoic anhydride (1.48 g), dissolve benzoic anhydride in 15 mL toluene, react at 80 °C for 30 minutes, add m-hydroxy-N,N-dimethylaniline to the system after 30 minutes, raise the temperature to 120 °C, and continue to react for 10 hours. TLC detects the reaction, and after the reaction is complete, the solvent is removed by rotary evaporation, and then recrystallized with n-butanol and purified by column chromatography to obtain intermediate product I (yield 70%).

[0066] Weigh the intermediate product I (1.56 g) and resorcinol (0.55 g), dissolve in 5 mL of trifluoroacetic acid, and reflux at 100 °C for 10 h. The reaction is detected by TLC and the reaction is complete. The solvent is removed by rotary evaporation. Then recrystallization is performed with ethyl acetate and the compound is purified by column chromatography to obtain the intermediate II (yield is 70%).

[0067] Take intermediate II (387.44 mg) and 5-chloro-8-hydroxyquinoline (283.07 mg), dissolve in 5 mL of dichloromethane, then add DMAP (122.17 mg) and DCC (412.66 mg), and react at 60 °C for 24 h. TLC detection reaction, after the reaction is complete, the solvent is removed by rotary evaporation. Then, dichloromethane and methanol are used as eluents in a volume ratio of 20 to 1, and column chromatography is used for purification to obtain a red solid product, that is, the final product is a compound based on the Rhodol structure (yield is 70%).

[0068] Embodiment 4:

[0069] A method for detecting barium ions in a water sample using a fluorescent probe comprises the following steps:

[0070] (1) Preparation of fluorescent probe: Weigh 13.7 mg of the Rhodol-based compound prepared in Example 1, i.e., the compound of formula (III), and dissolve it in acetonitrile and adjust the volume to 25 mL, pH = 7.4, to obtain a fluorescent probe stock solution; the concentration of the fluorescent probe stock solution is 1×10 -3 mol / L.

[0071] (2) Fluorescence spectrum measurement: Add the water sample to be tested to the fluorescent probe stock solution, and then adjust the volume with acetonitrile to pH = 7.4. After standing for 5 minutes, perform fluorescence emission spectrum measurement at a fixed excitation wavelength of 290 nm, and draw a curve of the fluorescence intensity change at the excited wavelength.

[0072] (3) Fluorescence spectrum analysis: The change in fluorescence emission spectrum intensity at 580 nm before and after the fluorescent probe solution is added to the water sample is calculated, and the barium ions in the water sample can be detected.

[0073] Experiment 1: Probe and Ba 2+ UV absorption, fluorescence emission and selectivity experiments of the reaction:

[0074] Control group: probe (10 μM), acetonitrile (10 mL), pH = 7.4; Experimental group: probe (10 μM), pH = 7.4, Ba 2+ (0.2 mM). The control group and the experimental group were reacted at room temperature for 5 min, and then the UV absorption and fluorescence emission spectra were measured at their maximum absorption as the single-photon excitation wavelength. The spectra are shown in Figure 1 and Figure 2 , Figure 1 and Figure 2 The horizontal axis is wavelength (nm), Figure 1 The vertical axis is the fluorescence intensity. Figure 2 The vertical axis is the ultraviolet absorption intensity. Figure 3 The probe responds to various metal ions. The metal ions detected are: Ba 2+ , Cu 2+ 、Ni 2+ 、Al 3+ , Mn 2+ Mg 2+ 、Cd 2+ 、Co 2+ , Ca 2+ 、Na + , Fe 3+ , Fe 2+ The metal ion concentration was 0.2 mM, and the samples were placed at room temperature for 5 min. The fluorescence emission spectra were measured by fixing the excitation wavelength at 290 nm, and the change curve of the fluorescence spectrum intensity was plotted. Figure 3 As shown, when Ba 2+ The fluorescence intensity is significantly enhanced when , while the intensity of other metal ions has no significant change. 2+ Better selectivity.

[0075] Experiment 2: Anti-interference experiment

[0076] (1) Preparation of probe stock solution: Weigh 13.7 mg of compound III (the rhodol-based compound prepared in Example 1), dissolve it in acetonitrile and make up to 25 mL to prepare a 1 mM probe stock solution.

[0077] (2) Preparation of ion stock solution: Use ultrapure water to prepare metal ion cation solution (Ba 2+ , Cu 2+ 、Ni 2+ 、Al 3+ , Mn 2+ Mg 2+ 、Cd 2+ 、Co 2+ , Ca 2+ 、Na + , Fe 3+ , Fe 2+ ) (10 mM). The metal salts of the prepared cationic solution are (BaCl2, CuCl2, NiCl2, AlCl3, MnCl2, MgCl2, CdCl2, CoCl2, CaCl2, NaCl, FeCl3, FeCl2).

[0078] (3) Interfering ion determination: Add acetonitrile solution to the prepared probe solution to make the probe concentration in the solution 10 μM, and add the prepared Ba 2+After adding the standard solution, the fluorescence intensity of the probe at a wavelength of 580 nm was measured. 2+ An equal amount of the configured interfering ion solution was added to the mixed solution, and then the changes in the fluorescence intensity values ​​before and after the addition were detected. The results showed that the probe had good anti-interference ability.

[0079] Drawing of standard curve

[0080] Take 10 10 mL volumetric flasks and add 1.0×10 -3 mol / L fluorescent probe solution (the same as the standard solution of fluorescent probe in step 1 of Example 4)) was added with 100 μL, and then 0, 20, 40, 60, 80, 100, 120, 140, 160, 180, 200 μL, 1.0×10 -2 mol / L Ba 2+ The standard solution was dissolved in acetonitrile solution and diluted to the mark, shaken, and placed at room temperature for 5 min. The fluorescence emission spectrum was determined at a fixed excitation wavelength of 290 nm. 2+ The concentration is taken as the horizontal axis, and the corresponding fluorescence emission spectrum intensity at 580nm is taken as the vertical axis to draw a standard curve, such as Figure 4 shown.

[0081] Method for detecting barium ions in water samples using fluorescent probes:

[0082] (1) Preparation of fluorescent probe: Weigh 13.7 mg of compound III (the compound based on the Rhodol structure prepared in Example 1), dissolve it in acetonitrile and adjust the volume to 25 mL, pH = 7.4, to obtain a standard solution of the fluorescent probe;

[0083] (2) Fluorescence spectrum measurement: Add the water sample to be tested to the fluorescent probe solution, and then dilute to volume with acetonitrile. After standing for 5 minutes, perform fluorescence emission spectrum measurement at a fixed excitation wavelength of 290 nm, and draw a curve of the fluorescence intensity change at the excited wavelength;

[0084] (3) Fluorescence spectrum analysis: The change in fluorescence emission spectrum intensity at 580 nm before and after the fluorescent probe solution is added to the water sample is calculated, and the barium ions in the water sample can be detected.

[0085] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

[0086] This background section is provided to generally present the context of the invention, and the work of the presently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither explicitly nor implicitly admitted to be prior art to the present invention.

Claims

1. A compound based on a Rhodol structure, characterized in that: The structural formula of the compound is: （Ⅲ）。 2. A method for preparing a compound based on a Rhodol structure, characterized in that The reaction route of this compound is: 。 3. The preparation method according to claim 2, characterized in that The following steps are involved: 1) dissolving benzoic anhydride in toluene; then adding m-hydroxy-N,N-diethylaniline to the above system, and continuing the reaction after heating; after the reaction is completed, evaporating the solvent, recrystallizing with n-butanol, and then purifying to obtain intermediate product I; 2) Dissolve the intermediate product I and resorcinol in trifluoroacetic acid, and then perform a reflux reaction; after the reaction is completed, evaporate the solvent, recrystallize with ethyl acetate, and then purify to obtain the intermediate II; 3) Dissolve intermediate II and 5-chloro-8-hydroxyquinoline in dichloromethane; then add DMAP and DCC, and react at room temperature overnight; after the reaction is complete, evaporate and remove the solvent; 4) Using dichloromethane and methanol as eluents, column chromatography was performed to purify the product to obtain a red solid, namely, compound III based on the Rhodol structure.

4. The preparation method according to claim 3, characterized in that: The solvent in step 1) is toluene; the molar ratio of m-hydroxy-N,N-diethylaniline and benzoic anhydride is 1:1-1.5; the reaction temperature in step 1) is 80-110°C, and the reaction time is 8-14 h; the temperature at which benzoic anhydride is dissolved in toluene is 70-90°C, and the dissolution time is 10-30 minutes; the solvent in step 2) is trifluoroacetic acid; the molar ratio of intermediate product I to resorcinol is 1:1; the temperature of the reflux reaction is 75-90°C, and the reaction time is 8-12 h; the solvent in step 3) is dichloromethane; the molar ratio of intermediate II to 5-chloro-8-hydroxyquinoline, DMAP and DCC is 1:1:1:2; the ratio of the volume mL of dichloromethane to the mass g of the intermediate II compound is 10:

1.

5. A fluorescent probe, characterized in that: The fluorescent probe contains the Rhodol structure-based compound as claimed in claim 1, or contains the Rhodol structure-based compound prepared by any one of the methods of claims 2-4.

6. Use of the fluorescent probe as claimed in claim 5 in detecting barium ions.

7. A method for detecting barium ions in water samples using the fluorescent probe as claimed in claim 5, characterized in that The following steps are involved: A reagent containing a fluorescent probe is used as a fluorescent reagent; a water sample containing barium ions is added to the fluorescent reagent, and then excited with a fixed excitation wavelength to observe the change in the intensity of the fluorescence emission spectrum before and after the addition of the water sample to be tested, that is, the barium ions in the water sample are detected.

8. The method for detecting barium ions in water samples using a fluorescent probe according to claim 7, characterized in that The following steps are involved: (1) Prepare the fluorescent probe solution: weigh the compound based on the Rhodol structure and dissolve it in acetonitrile solution to obtain the standard solution of the fluorescent probe; (2) Determination of fluorescence spectrum: Add the water sample to be tested into the fluorescent probe, measure the fluorescence emission spectrum with a fixed excitation wavelength of 290 nm, and draw a curve of the change of fluorescence intensity at the excited wavelength; (3) Fluorescence spectrum analysis: Calculate the intensity change △F of the fluorescence emission spectrum at 580 nm before and after adding the water sample to the fluorescent probe solution, that is, detect the barium ions in the water sample.

9. The method for detecting barium ions in water samples using a fluorescent probe according to claim 8, characterized in that: In step 1), the ratio of the mass mg of the compound based on the Rhodol structure to the volume mL of acetonitrile is 13.7:25; the pH value of the standard solution is 7.4; the molar concentration of the standard solution is 1.0×10 -3 mol / L.

10. The method for detecting barium ions in water samples using a fluorescent probe according to claim 8, characterized in that: The method of fluorescence spectral analysis described in step 3) is specifically as follows: when the fluorescence emission spectrum intensity change △F at 580 nm corresponding to the fluorescent probe solution before and after the addition of the fluorescent probe solution to the water sample to be tested is large, it indicates that the water sample to be tested contains barium ions; when the fluorescence emission spectrum intensity change △F at 580 nm corresponding to the fluorescent probe solution before and after the addition of the fluorescent probe solution to the water sample to be tested is small, it indicates that the water sample to be tested does not contain barium ions.

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