A benzene group-xanthene derivative, a preparation method and a metal ion detection fluorescent probe

Abstract

The present application relates to the technical field of optical sensing imaging detection, in particular to a benzene group-xanthene derivative, a preparation method and a metal ion detection fluorescent probe. The benzene group-xanthene derivative has a general formula as shown in formula I: The benzene group-xanthene derivative of the present application can realize high selectivity, high sensitivity and in-situ response to metal ions, especially copper ions, under certain environment, and the detection limit can reach 10 ‑8 The order of magnitude of M; the preparation method is simple and easy to operate, and the cost is low; the dye is used as an optical signal reporting group to design a molecular fluorescent probe for detecting copper ions; meanwhile, the dye can also be used as a platform to design probes for recognizing various molecules or ions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical sensing imaging detection, and particularly relates to a benzene group-xanthene derivative, a preparation method and a metal ion detection fluorescent probe. BACKGROUND

[0002] The fluorescent probe has the characteristics of simple design, high sensitivity and good selectivity, and is widely used in various fields such as environmental monitoring and medicine. Rhodamine and xanthene derivatives have good application prospects in analyte detection and fluorescence imaging due to their excellent properties. In biological systems, the probe needs to have a large stokes shift and excellent water solubility, so it is necessary to develop a fluorescent probe with excellent performance.

[0003] Metal, especially copper, is an essential trace metal element in the human body. Due to the presence of copper-containing enzymes, copper plays an important role in many electron transfer biological processes. Disturbance of intracellular copper ion concentration can cause neurological diseases such as Alzheimer's disease or rickets. The World Health Organization recommends daily copper intake: adults (1.5-3.0 mg), children (1.5-2.5 mg) and infants (0.4-0.6 mg). Therefore, it is of great significance to quantitatively detect copper ions in the environment. The currently developed copper ion probes still have small stokes shift, poor selectivity and water solubility, and short emission wavelength (<550 nm), so new fluorescent probes need to be developed to solve these problems. SUMMARY

[0004] The present application aims at the defects of the existing metal ion probes, such as low selectivity and sensitivity, single emission wavelength, unstable structure and optical signal, and the inability to meet the requirements of wavelength, selectivity and sensitivity in biomolecular detection, and provides a benzene group-xanthene derivative, a preparation method and a metal ion detection fluorescent probe.

[0005] The first aspect of the present application provides a benzene group-xanthene derivative, which has a general formula as shown in formula I:

[0006]

[0007] wherein R1, R2, R3 are each independently selected from C1-C4 alkyl, and X is selected from O or S.

[0008] Preferably, R1, R2, R3 are each independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl.

[0009] Preferably, the benzene group-xanthene derivative is selected from any one of the following:

[0010]

[0011] The second aspect of the present application provides a method for preparing the above-mentioned benzogroup-xanthene derivative, which is prepared from a compound of formula I-1, and the reaction equation is as follows:

[0012]

[0013] wherein R1, R2, R3, X are defined as in the first aspect of the present application.

[0014] Preferably, the method comprises the following steps:

[0015] 1) mixing the compound of formula I-1 with R3I in a solution of R4Cl2 and stirring at room temperature, collecting the precipitate obtained by filtration, and recrystallizing to obtain a solid; wherein R3, R4 are each independently selected from C1-C4 alkyl;

[0016] 2) dissolving the solid provided in step 1) in a saturated solution of NaBF4 to perform anion exchange to obtain the benzogroup-xanthene derivative.

[0017] Preferably, the method comprises at least one of the following technical features:

[0018] A1) in step 1), the molar ratio of the compound of formula I-1 to R3I is 1:(10-20);

[0019] A2) in step 1), the mass-volume ratio of the compound of formula I-1 to the solution of R4Cl2 is (0.4-0.5)g:(5-20)mL;

[0020] A3) in step 1), R3, R4 are each independently selected from methyl, ethyl;

[0021] A4) in step 1), the stirring time is 24h-72h;

[0022] A5) in step 1), the volume ratio of the solvents used in the recrystallization process is 1:

[0023] (1-3).

[0024] Preferably, the method comprises at least one of the following technical features:

[0025] B1) in step 2), the solvent used for dissolving the solid is an alcohol;

[0026] B2) the mass-volume ratio of the compound of formula I-1 to the saturated solution of NaBF4 is (0.4-0.5)g:(10-30)mL.

[0027] The third aspect of the present application provides use of the above-mentioned benzene group-xanthene derivative for preparing a metal ion detection fluorescent probe.

[0028] The fourth aspect of the present application provides a metal ion detection fluorescent probe comprising the benzene group-xanthene derivative of the first aspect of the present application.

[0029] Preferably, the detection solvent system of the metal ion detection fluorescent probe is selected from any one of an alcohol-water solution or an acetonitrile-water solution.

[0030] The present application has the following beneficial effects:

[0031] The benzene group-xanthene derivative of the present application can realize high selectivity and high sensitivity to metal ions, especially copper ions, in-situ response under certain environment, and the detection limit can reach 10 -8 M order of magnitude; the preparation method is simple and easy to operate, and the cost is low; the dye is used as an optical signal reporter group to design a molecular fluorescent probe for detecting copper ions; at the same time, the dye can also be used as a platform to design probes for recognizing various molecules or ions. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is the H NMR spectrum of the compound I of Example 1. 1

[0033] Figure 2 is the C NMR spectrum of the compound I of Example 1. 13

[0034] Figure 3 is the HRMS spectrum of the compound I of Example 1.

[0035] Figure 4 is the H NMR spectrum of the compound I-1 of Example 2. 1

[0036] Figure 5 is the C NMR spectrum of the compound I-1 of Example 2. 13

[0037] Figure 6 is the HRMS spectrum of the compound I-1 of Example 2.

[0038] Figure 7 is the fluorescence spectrum of the compound I as a probe in acetonitrile water (H2O / CH3CN (v / v, 4 / 1)) by adding different metal ions.

[0039] Figure 8 ​​​​is the fluorescence spectrum column chart of compound I in Example 4 as a probe in acetonitrile water (H2O / CH3CN (v / v, 4 / 1)) with different metal ions added dropwise at 632 nm.

[0040] Figure 9 is the limit of detection calculation data of compound I in Example 5 as a probe in acetonitrile water (H2O / CH3CN (v / v, 4 / 1)) with different concentrations of copper ions added dropwise at 632 nm.

[0041] Figure 10 is the UV absorption spectrum chart of compound I in Example 6 as a probe in acetonitrile water (H2O / CH3CN (v / v, 4 / 1)) with different metal ions added dropwise.

[0042] Figure 11 is the color change chart of compound I in Example 7 as a probe with different ions added.

[0043] Figure 12 is the detection column chart of compound I in Example 8 as a probe against copper ions.

[0044] Figure 13 is the fluorescence emission spectrum dot chart of compound I in Example 9 as a probe in acetonitrile water (H2O / CH3CN (v / v, 4 / 1)) with different concentrations of copper ions added dropwise.

[0045] Figure 14 is the pH response range test of compound I in Example 10 as a probe against copper ions.

[0046] Figure 15 is the MS chart after the probe reacts with copper ions.

[0047] Figure 16 is the schematic diagram of the probe reacting with copper ions. DETAILED DESCRIPTION

[0048] The present application is herein described, by way of example only, with reference to certain embodiments thereof. It is contemplated that the application described herein will be practiced with variation of the procedure described, which will occur to those skilled in the art. The application described herein can be implemented in hardware that is purpose built, or in software running on a general purpose computer. The application described herein can also be implemented in a combination of purpose built hardware and software running on a general purpose computer.

[0049] It should be noted that the process equipment or devices not specifically mentioned in the following examples are all conventional equipment or devices in the art.

[0050] Benzogroup-xanthene derivatives

[0051] A benzogroup-xanthene derivative has a general formula as shown in Formula I:

[0052]

[0053] wherein R1, R2, R3 are each independently selected from C1-C4 alkyl, and X is selected from O, S.

[0054] Optionally, R1, R2, R3 are each independently selected from methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl or t-butyl.

[0055] In a preferred embodiment, R1, R2, R3 are each independently methyl, ethyl or n-propyl.

[0056] In a preferred embodiment, X is selected from S.

[0057] In a preferred embodiment, X is selected from O.

[0058] In a preferred embodiment, the benzogroup-xanthene derivative is selected from any one of the following:

[0059]

[0060]

[0061] Process for the preparation of benzogroup-xanthene derivatives

[0062] The second aspect of the present application provides a method for preparing the above-mentioned benzogroup-xanthene derivative, which is prepared from a compound of formula I-1, and the reaction equation is as follows:

[0063]

[0064] wherein R1, R2, R3 are each independently selected from C1-C4 alkyl, and X is selected from O, S.

[0065] Optionally, R1, R2, R3 are each independently selected from methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl or t-butyl.

[0066] In a preferred embodiment, R1, R2, R3 are each independently methyl, ethyl or n-propyl.

[0067] In a preferred embodiment, X is selected from S.

[0068] In a preferred embodiment, X is selected from O.

[0069] In a preferred embodiment, the method comprises the following steps:

[0070] 1) mixing the compound of formula I-1 with R3I in R4Cl2 solution and stirring at room temperature, collecting the resulting precipitate by filtration and recrystallizing to obtain a solid; wherein R3, R4 are each independently selected from C1-C4 alkyl;

[0071] 2) dissolving the solid provided in step 1) and performing anion exchange in a saturated solution of NaBF4 to obtain the benzogroup-xanthene derivative.

[0072] In the preparation method of the benzogroup-xanthene derivative provided by the present application, the preparation method of the compound of formula I-1 is as follows:

[0073]

[0074] mixing the compound I-2 and 2-hydrazinoethanol in a methanol solution and stirring at room temperature overnight, then collecting the resulting precipitate by filtration and recrystallizing in an acetonitrile and / or diethyl ether solution to obtain white powder I-1.

[0075] wherein the molar ratio of the compound I-2 and 2-hydrazinoethanol is 1:(2-5). Alternatively, the molar ratio of the compound I-2 and 2-hydrazinoethanol can be 1:(2-4.33) or 1:(4.33-5), etc.

[0076] In the preparation method of the benzogroup-xanthene derivative provided by the present application, in step 1), the molar ratio of the compound I-1 and R3I is 1:(10-20). Alternatively, the molar ratio of the compound I-1 and R3I can be 1:(10-16) or 1:(16-20), etc.

[0077] In the preparation method of the benzogroup-xanthene derivative provided by the present application, in step 1), the mass-volume ratio of the compound I-1 and R4Cl2 solution is (0.4-0.5) g:(5-20) mL. Alternatively, the mass-volume ratio of the compound I-1 and R4Cl2 solution can be (0.4-0.5) g:5 mL, 0.49 g:(5-20) mL, 0.49 g:(5-10) mL or 0.49 g:(10-20) mL.

[0078] In the preparation method of the benzogroup-xanthene derivative provided by the present application, in step 1), R3, R4 are each independently selected from C1-C4 methyl, ethyl, n-propyl. R3I can be CH3I. R4Cl2 solution can be CH2Cl2.

[0079] In the preparation method of the benzogroup-xanthene derivative provided by the present application, in step 1), the stirring time is 24 h-72 h. Alternatively, the stirring time can be 24 h-36 h, 36 h-48 h or 48 h-72 h, etc.

[0080] In the preparation method of the benzo group-xanthene derivative provided by the present application, in step 1), the solvent for the recrystallization process is acetonitrile and diethyl ether, and the volume ratio of the acetonitrile and diethyl ether is 1:(1-3). Alternatively, the volume ratio of the acetonitrile and diethyl ether can be, for example, 1:(1-2) or 1:(2-3), etc.

[0081] In the preparation method of the benzo group-xanthene derivative provided by the present application, in step 2), the solvent for dissolving the solid is an alcohol. The alcohol can be, for example, methanol, etc.

[0082] In the preparation method of the benzo group-xanthene derivative provided by the present application, in step 2), the mass-volume ratio of the I-1 compound to the saturated solution of NaBF4 is (0.4-0.5) g:(10-30) mL. Alternatively, the mass-volume ratio of the I-1 compound to the saturated solution of NaBF4 can be, for example, 0.49 g:(10-30) mL, 0.49 g:(10-15) mL, 0.49 g:(15-30) mL, or (0.4-0.5) g:15 mL, etc.

[0083] In a specific embodiment, the benzo group-xanthene derivative provided by the present application is prepared by the following method:

[0084]

[0085] Compound I-1 and CH3I are mixed in a dichloromethane solution and stirred at room temperature for 24-72 hours. Then the obtained precipitate is collected by filtration and recrystallized in an acetonitrile / diethyl ether solution. The obtained solid is dissolved in methanol, and then an anion exchange is performed by adding a saturated solution of NaBF4 to obtain white powder I.

[0086] The preparation method of compound I-1 is as follows:

[0087]

[0088] Compound I-2 and 2-hydrazinoethanol are mixed in a methanol solution and stirred at room temperature overnight, and then the obtained precipitate is collected by filtration and recrystallized in an acetonitrile and / or diethyl ether solution to obtain white powder I-1.

[0089] Metal ion detection fluorescent probes

[0090] The metal ion detection fluorescent probe in the present application includes the above-mentioned benzo group-xanthene derivative, and the detection solvent system of the metal ion detection probe is selected from any one of an alcohol-water solution or an acetonitrile-water solution.

[0091] Principle: after the probe reacts with a metal ion such as copper ion, the spiro lactam ring is opened, causing a significant enhancement of fluorescence, and the specific principle diagram is as follows:Figure 16 , and the mass spectrum is shown in Figure 15 .

[0092] The application will be further described in conjunction with specific examples. It should be understood that the following examples are intended to illustrate the application and are not intended to limit the scope of the application. The experimental methods in the following examples, if not specified, are selected according to the conventional methods and conditions, or according to the commercial instructions. The reagents and raw materials used in the application are commercially available.

[0093] Preparation of compound I in Example 1

[0094] The specific method is as follows:

[0095]

[0096] A mixture of I-1 (1.0 mmol, 0.49 g) and CH3I (16 mmol, 1 mL) in CH2Cl2(5 mL) was mixed and stirred at room temperature for 72 hours. Then the obtained precipitate was collected by filtration, and then recrystallized from acetonitrile / ethyl ether (v / v = 1 / 2). The obtained solid was dissolved in methanol (2.0 mL), and then anion exchange was carried out by adding a saturated solution of NaBF4(15 mL). The final product I was collected as a white powder (183 mg, yield 31%).

[0097] Mp: 283-285 °C. HRMS (ESI) calcd. m / z 501.1955 [M] + , found. m / z 501.1971. 1 H NMR (400 MHz, CDCl3) 10.49 (s, 1H), 8.12-8.06 (m, 2H), 7.77 (d, J = 9.2 Hz, 1H), 7.71 (t, J = 7.4 Hz, 1H), 760 (t, J = 7.4 Hz, 1H), 7.16 (d, J = 7.6 Hz, 1H), 6.49-6.44 (m, 2H), 6.38 (dd, J = 8.8, 2.2 Hz, 1H), 4.15 (s, 3H), 3.36 (q, J = 7.0 Hz, 4H), 3.29-3.16 (m, 2H), 2.52-2.33 (m, 2H), 1.19 (t, J = 7.0 Hz, 6H). 13C NMR (100 MHz, CDC13) 166.57, 161.28, 152.67, 151.51, 148.59, 145.82, 136.67, 133.32, 130.23, 129.93, 129.05, 127.02, 123.87, 123.47, 120.87, 117.26, 112.85, 108.67, 102.32, 96.99, 64.50, 58.55, 53.58, 43.63, 39.47, 11.61.

[0098] 1 H NMR, 13 C NMR, HRMS chart results are shown in Figures 1-3 .

[0099] Example 2

[0100] Preparation method of compound I-1

[0101]

[0102] I-2 (1.0 mmol, 0.44 g) and 2-hydroxyethyl hydrazine (2.0 mmol, 0.15 g) were added to anhydrous methanol (5.0 mL), then stirred at 25°C for 24 hours. After that, the gray precipitate was collected by filtration to obtain the crude product, then recrystallized from acetonitrile to obtain the pure final product I-1 (0.22 g, 45% yield). Mp: 236-238°C.

[0103] 1 H NMR (400 MHz, DMSO-d6) δ 9.08 (s, 1H), 8.07 (d, J = 8.8 Hz, 1H), 7.90 (d, J = 7.4 Hz, 1H), 7.58 (t, J = 7.3 Hz, 1H), 7.49 (t, J = 7.7 Hz, 2H), 7.02 (d, J = 7.5 Hz, 1H), 6.39 (d, J = 10.2 Hz, 2H), 6.33 (d, J = 8.6 Hz, 1H), 4.91 (t, J = 6.1 Hz, 1H), 4.50 (t, J = 5.2 Hz, 1H), 3.29 (d, J = 6.7 Hz, 4H), 3.00 - 2.94 (m, 2H), 2.40 (s, 1H), 2.29 (s, 1H), 1.04 (t, J = 6.7 Hz, 6H).

[0104] 13C NMR (101 MHz, DMSO-d6) δ 166.17, 155.37, 152.19, 150.40, 149.93, 148.56, 148.31, 133.40, 131.51, 131.21, 129.63, 128.09, 124.45, 124.24, 122.79, 117.11, 112.44, 108.80, 104.35, 97.19, 65.07, 58.96, 52.24, 43.78, 12.49.

[0105] HRMS (ESI) m / z calcd. 487.1798 [M] + , found. m / z 487.1799 [M] +

[0106] Preparation of compound I-1 1 H NMR, 13 C NMR spectra, HRMS results are shown in Figures 4-6 .

[0107] Example 3

[0108] Preparation of compound I-1

[0109] Compound I-2 (3.0 mmol, 1.33 g) and 2-hydrazine ethanol (13 mmol, 1 mL) were mixed in methanol solution (20 mL) and stirred at room temperature overnight, then the resulting precipitate was collected by filtration, recrystallized in acetonitrile / ethyl ether solution (v / v = 1 / 2) to obtain white powder I-1 (758 mg, yield 52%). Mp: 236-238 °C.

[0110] Example 4 Determination of optical properties of compound I as a probe:

[0111] The specific method is as follows:

[0112] Determination of optical properties of compound I in different metal ions: the compound was dissolved in (H2O / CH3CN (v / v, 4 / 1)) solvent to prepare 1 × 10 -5 mol / L of the test solution 3 mL, various ions (2.5 × 10 -4 mol / L) were added, and the fluorescence emission spectrum was obtained as shown in Figure 7 .

[0113] Determination of optical properties of compound I in different metal ions: the compound was dissolved in (H2O / CH3CN (v / v, 4 / 1)) solvent to prepare 1 × 10 -5 mol / L of the test solution 3 mL, various ions (2.5 × 10 -4fluorescence emission spectrum was obtained, and the fluorescence emission intensity at 632 nm was recorded and plotted as shown in Figure 8

[0114] Example 5: Detection limit determination of compound I as a probe:

[0115] The specific method is as follows:

[0116] Optical property determination of compound in different concentrations of copper ions: The compound was dissolved in acetonitrile water (H2O / CH3CN (v / v, 4 / 1)) solvent to prepare 1×10 -5 mol / L of the test solution 3 mL, and Cu 2+ ions (0-5×10 -6 mol / L) were gradually added, and the fluorescence emission spectrum was recorded, and the detection limit was calculated as 60.8 nM, as shown in Figure 9

[0117] Example 6: Ion selectivity detection of compound I as a probe for different ions:

[0118] The compound was dissolved in (H2O / CH3CN (v / v, 4 / 1)) solvent to prepare 1×10 -5 mol / L of the test solution 3 mL, and various ions (2.5×10 -4 mol / L) were added, and the ultraviolet absorption spectrum was obtained, as shown in Figure 10 At about 600 nm, the ultraviolet absorption was significantly enhanced after the addition of copper ions, and other ions showed no obvious change.

[0119] Example 7: Color change of compound I as a probe after the addition of different ions:

[0120] The compound was dissolved in (H2O / CH3CN (v / v, 4 / 1)) solvent to prepare 1×10 -5 mol / L of the test solution 3 mL, and various ions (2.5×10 -4 mol / L) were added, and the color change was placed in a cuvette, as shown in Figure 11 After the addition of copper ions, the color changed to light purple, and other ions showed no obvious change except iron ions.

[0121] Example 8: Anti-interference detection of compound I as a probe for copper ions:

[0122] The compound was dissolved in (H2O / CH3CN (v / v, 4 / 1)) solvent to prepare 1×10 -5 mol / L of the test solution 3 mL, and copper ions and other various ions (2.5×10 -4 ​​mol / L), fluorescence emission spectra were obtained, and the ratio of fluorescence emission intensity at 632 nm (F-F0) / (FCu-F0) was plotted against the ion species, as shown in the bar graph Figure 12 As shown in the figure. The fluorescence intensity of copper ions was not affected after adding other ions.

[0123] Example 9: Fluorescence emission spectra of continuous titration of copper ions by compound I as a probe:

[0124] The compound was dissolved in (H2O / CH3CN (v / v, 4 / 1)) solvent to prepare 1×10 -5 mol / L of the test solution 3 mL, and different concentrations of copper ions (0-3×10 -4 mol / L) were added. Fluorescence emission spectra were obtained, and the fluorescence emission intensity at 632 nm was plotted against the ion concentration, as shown in the dotted line graph. Figure 13

[0125] Example 10: pH response range test of copper ions by compound I as a probe:

[0126] The compound was dissolved in (H2O / CH3CN (v / v, 4 / 1)) solvent to prepare 1×10 -5 mol / L of the test solution 3 mL, and the pH was adjusted to 1-13, and copper ions (2.5×10 -4 mol / L) were added. Fluorescence emission spectra were obtained, and the fluorescence emission intensity at 632 nm was plotted against the pH value, as shown in the dotted line graph. Figure 14 There was a good response in the pH range of 5-9.

[0127] The above is a further detailed description of the present application in conjunction with specific embodiments, which cannot be considered as limiting the specific implementation of the present application to these descriptions. For ordinary skilled persons in the technical field to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be considered as falling within the protection scope of the present application. As a fluorescent dye, the present application is a new compound, which cannot be considered as limiting the present application to fluorescent dyes. For ordinary skilled persons in the technical field to which the present application belongs, based on the same mechanism of action of the present application as a fluorescent dye, a number of simple inferences can be made, which should be considered as falling within the protection scope of the present application.​

Claims

1. A benzogroup-xanthene derivative, characterized by, having a general formula as shown in formula I: wherein R1, R2, R3 are each independently selected from C1-C4 alkyl, and X is selected from O, S.

2. The benzogroup-xanthene derivative according to claim 1, characterized in that, R1, R2, R3 are each independently selected from methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl or t-butyl.

3. The benzogroup-xanthene derivative according to claim 1 or 2, characterized in that, The benzene group-xanthene derivative is selected from any one of the following:

4. Process for the preparation of a benzogroup-xanthene derivative according to any one of claims 1 to 3, characterized in that, The benzene group-xanthene derivative is prepared from a compound of formula I-1, and the reaction equation is as follows: wherein R1, R2, R3, X are as defined in claims 1-2.

5. The method for preparing the benzo[a]-oxanthracene derivative according to claim 4, characterized in that, Specifically comprising the following steps: 1) mixing the compound of formula I-1 with R3I in a solution of R4Cl2 and stirring at room temperature, collecting the resulting precipitate by filtration, and recrystallizing to obtain a solid; wherein R3, R4 are each independently selected from C1-C4 alkyl; 2) dissolving the solid provided in step 1) in a saturated solution of NaBF4 to perform anion exchange to obtain the benzene group-xanthene derivative.

6. The method for preparing the benzo[a]-oxanthracene derivative according to claim 4 or 5, characterized in that, At least one of the following technical features is included: A1) in step 1), the molar ratio of the compound of formula I-1 to R3I is 1:(10-20); A2) in step 1), the mass-volume ratio of the compound of formula I-1 to the solution of R4Cl2 is (0.4-0.5)g:(5-20)mL; A3) in step 1), R3, R4 are each independently selected from methyl, ethyl, n-propyl; A4) in step 1), the stirring time is 24h-72h; A5) in step 1), the solvent used in the recrystallization process is acetonitrile and diethyl ether, and the volume ratio of the acetonitrile to diethyl ether is 1: (1～3)。 7. The method for preparing the benzo[a]-oxanthracene derivative according to claim 5, characterized in that, At least one of the following technical features is included: B1) in step 2), the solvent used for dissolving the solid is an alcohol; B2) the mass-volume ratio of the compound of formula I-1 to the saturated solution of NaBF4 is (0.4-0.5)g:(10-30)mL.

8. The benzene group-xanthene derivative according to any one of claims 1-3 for use in the preparation of a fluorescent probe for detecting copper ions.

9. A fluorescent probe for detecting metal ions, characterized by, The benzene group-xanthene derivative according to any one of claims 1-3.

10. The metal ion detecting fluorescent probe according to claim 9, wherein The detection solvent system of the fluorescent probe for detecting metal ions is selected from any one of an alcohol-water solution or an acetonitrile-water solution.

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