Non-conjugated fluorescent polymer independent of excitation wavelength
The non-conjugated fluorescent polymer prepared by click polymerization solves the problem of emission wavelength dependence on excitation wavelength, achieving stable emission over a wide excitation wavelength range and improving detection and bioimaging performance.
Patent Information
- Application Number
- CN202511770838.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-28
- Publication Date
- 2026-01-27
AI Technical Summary
The emission wavelength of traditional non-conjugated fluorescent materials depends on the change in excitation wavelength, which leads to fluorescence signal interference and affects the accuracy of detection and biological imaging.
Non-conjugated fluorescent polymers are prepared by click polymerization of secondary or primary amine monomers with activated alkyne monomers, thereby constructing luminescent structures with specific spatial conformations and achieving decoupling between excitation and emission wavelengths.
Maintaining a stable emission wavelength over a wide excitation wavelength range overcomes the signal interference defects of traditional non-conjugated fluorescent materials, improving the sensitivity and accuracy of detection and biological imaging.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of fluorescent polymer technology, and more specifically to a non-conjugated fluorescent polymer that is independent of excitation wavelength. Background Technology
[0002] In recent years, with in-depth research in the field of luminescent materials, researchers have discovered a special class of polymers without conventional chromophores that exhibit significant photoluminescence properties in their aggregated state. These unconventional luminescent materials break with traditional understanding; their molecular structures do not contain classic π-conjugated chromophores, but rather consist solely of electron-rich heteroatoms (such as nitrogen (N), oxygen (O), sulfur (S), phosphorus (P), etc.)) and / or unsaturated bonds forming unconventional chromophores. Compared to polymer fluorescent materials that rely on traditional conjugated systems, these unconventional luminescent materials are not only simple to prepare and exhibit excellent structural stability, but also possess good hydrophilicity and biocompatibility. Therefore, they show broad application prospects in cutting-edge fields such as metal ion sensing, bioimaging, cell tracing, and drug / gene delivery tracking, becoming a research hotspot in materials science.
[0003] However, currently reported non-conjugated fluorescent materials generally suffer from a key technical bottleneck—excitation wavelength-dependent emission characteristics. Specifically, the fluorescence emission wavelength of the material exhibits a redshift with changes in the excitation wavelength. This phenomenon can cause severe fluorescence signal interference in practical applications such as metal ion detection and cell imaging. For example, in multi-component detection systems, the shift in emission peak positions under different excitation wavelengths can lead to overlapping detection signals, significantly reducing analytical sensitivity and accuracy. In bioimaging, excitation wavelength dependence can increase imaging background noise, affecting the clear resolution of cell or tissue structures. Therefore, developing non-conjugated fluorescent materials without excitation wavelength-dependent emission characteristics has become a crucial need to overcome existing technological limitations and expand their application scope. Summary of the Invention
[0004] A problem with existing technologies is that the emission wavelength of traditional non-conjugated fluorescent polymers depends on the excitation wavelength, which easily leads to fluorescence signal interference. To address this problem, this invention provides a non-conjugated fluorescent polymer that is independent of the excitation wavelength. This polymer is obtained by click polymerization of a secondary amine alcohol or primary amine monomer with an activated alkyne monomer. The secondary amine alcohol is 3-hydroxypiperidine or 3-piperidinemethanol, the primary amine monomer is cyclohexane-1,3-diamine or m-phenylenediamine, and the activated alkyne monomer has alkynyl groups at both ends of its molecular chain.
[0005] Preferably, the molar ratio of the secondary amine alcohol or primary amine monomer to the activated acetylene monomer in the click polymerization reaction is 1:1.
[0006] Preferably, the activated alkyne monomer comprises the following general structural formula: ; Formula I; ; Formula II; In the above structural formula, the value of m ranges from 1 to 20.
[0007] Preferably, the activated alkyne monomer is ethylene glycol dipropynate, 1,4-butanediol dipropynate, 1,6-hexanediol dipropynate, or polyethylene glycol-alkyne.
[0008] Preferably, the non-conjugated fluorescent polymer comprises the following general structural formula: ; Formula I; ; Formula II; ; Formula III; ; Formula IV; ; Formula V; ;Form VI; In the above structural formula, the value of n is determined based on the reaction temperature, reaction time, and specific amount of reactants used in the click reaction, while the value of m is determined based on the chemical structure of the activated acetylene monomer.
[0009] The present invention has the following beneficial effects: This invention proposes a class of non-conjugated fluorescent polymer materials based on amino / hydroxy-yne or amino-yne click polymerization through innovative molecular structure design. By precisely controlling the rigidity-flexibility balance of the polymer chains, a luminescent structure with a specific spatial conformation is constructed, thereby achieving decoupling between the excitation and emission wavelengths. Experiments show that this type of material maintains a stable emission wavelength over a wide excitation wavelength range, effectively overcoming the signal interference defects of traditional non-conjugated fluorescent materials. This breakthrough not only provides a novel material platform for the detection applications of non-conjugated fluorescent polymers but also demonstrates significant technological advantages and industrial value in fields such as metal ion sensing and high-resolution bioimaging. Attached Figure Description
[0010] Figure 1 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Example 1 at different excitation wavelengths.
[0011] Figure 2 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Example 2 at different excitation wavelengths.
[0012] Figure 3 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Example 3 at different excitation wavelengths.
[0013] Figure 4 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Example 4 at different excitation wavelengths.
[0014] Figure 5 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Example 5 at different excitation wavelengths.
[0015] Figure 6 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Example 6 at different excitation wavelengths.
[0016] Figure 7 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Example 7 at different excitation wavelengths.
[0017] Figure 8 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Example 8 at different excitation wavelengths.
[0018] Figure 9 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Comparative Example 1 at different excitation wavelengths.
[0019] Figure 10 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Comparative Example 2 at different excitation wavelengths.
[0020] Figure 11 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Comparative Example 3 at different excitation wavelengths.
[0021] Figure 12 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Comparative Example 4 at different excitation wavelengths.
[0022] Figure 13 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Comparative Example 5 at different excitation wavelengths.
[0023] Figure 14 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Comparative Example 6 at different excitation wavelengths.
[0024] Figure 15 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Comparative Example 7 at different excitation wavelengths.
[0025] Figure 16 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Comparative Example 8 at different excitation wavelengths.
[0026] Figure 17 Fluorescence emission spectra of the non-conjugated fluorescent polymer obtained in Comparative Example 9 at different excitation wavelengths.
[0027] Figure 18 Example 1: Anti-counterfeiting application effect diagram of the fluorescent polymer obtained.
[0028] Figure 19 Example 5: The effect of the fluorescent polymer specifically recognizing ferric ions.
[0029] Figure 20 Linear relationship of quantitative detection of ferric ion concentration by fluorescent polymer obtained in Example 5.
[0030] Figure 21 Example 5: Fluorescence images of the fluorescent polymer obtained in cells under different fluorescence excitation wavelengths when used for fluorescence imaging.
[0031] Figure 22 Fluorescence color test diagram of the fluorescent polymer obtained in Example 5 and doxorubicin. Detailed Implementation
[0032] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.
[0033] The activated alkyne monomer used in the following embodiments of the present invention It was synthesized according to the method reported in the literature (PolymerChemistry, 2020, 11(14): 2568-2575.).
[0034] Example 1
[0035] Cyclohexane-1,3-diamine (0.114 g, 1 equiv) and ethylene glycol dipropynate (0.166 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, and the solid precipitate was collected, dried, and the non-conjugated fluorescent polymer (LP-1) was obtained. (See attached instructions.) Figure 1 As shown, the emission wavelength of LP-1 fluorescence does not shift with the excitation wavelength and is not dependent on the excitation wavelength.
[0036] The chemical formulas involved in the above reaction are as follows: .
[0037] Example 2
[0038] 0.108 g (1 equiv) of m-phenylenediamine and 0.166 g (1 equiv) of ethylene glycol dipropynate were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, and the solid precipitate was collected, dried, and the non-conjugated fluorescent polymer (LP-2) was obtained. (See attached instructions.) Figure 2 As shown, the emission wavelength of the LP-2 fluorescence test does not shift with the excitation wavelength and is not dependent on the excitation wavelength.
[0039] The chemical formulas involved in the above reaction are as follows: .
[0040] Example 3
[0041] 3-Hydroxypiperidine (0.101 g, 1 equiv) and ethylene glycol dipropynate (0.166 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, the solid precipitate was collected, and dried to obtain the non-conjugated fluorescent polymer (LP-5). (See attached instructions) Figure 3 As shown, the emission wavelength of LP-5 fluorescence does not shift with the excitation wavelength and is not wavelength-dependent.
[0042] The chemical formulas involved in the above reaction are as follows: .
[0043] Example 4
[0044] 3-Piperidinemethanol (0.115 g, 1 equiv) and ethylene glycol dipropynate (0.166 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, the solid precipitate was collected, and dried to obtain the non-conjugated fluorescent polymer (LP-6). (See attached instructions) Figure 4 As shown, the emission wavelength of LP-6 fluorescence does not shift with the excitation wavelength and is not wavelength-dependent.
[0045] The chemical formulas involved in the above reaction are as follows: .
[0046] Example 5
[0047] 3-Piperidinemethanol (0.115 g, 1 equiv) and 1,4-butanediol dipropynate (0.194 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, and the solid precipitate was collected, dried, and the non-conjugated fluorescent polymer (P-8) was obtained. (See attached instructions.) Figure 5 As shown, the emission wavelength of the P-8 fluorescence test does not shift with the excitation wavelength and is not dependent on the excitation wavelength.
[0048] The chemical formulas involved in the above reaction are as follows: .
[0049] Example 6
[0050] 3-Piperidinemethanol (0.115 g, 1 equiv) and 1,6-hexanediol dipropynate (0.222 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, and the solid precipitate was collected, dried, and the non-conjugated fluorescent polymer (P-9) was obtained. (See attached instructions) Figure 6 As shown, the emission wavelength of the P-9 fluorescence test does not shift with the excitation wavelength and is not dependent on the excitation wavelength.
[0051] The chemical formulas involved in the above reaction are as follows: .
[0052] Example 7
[0053] 3-Piperidinemethanol (0.115 g, 1 equiv) and polyethylene glycol (400)-yne (0.504 g, 1 equiv, CAS No.: 25322-68-3) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, the solid precipitate was collected, and dried to obtain the non-conjugated fluorescent polymer (LP-7). (See attached instructions) Figure 7 As shown, the emission wavelength of the LP-7 fluorescence test does not shift with the excitation wavelength and is not dependent on the excitation wavelength.
[0054] The chemical formulas involved in the above reaction are as follows: .
[0055] Example 8
[0056] 3-Piperidinemethanol (0.115 g, 1 equiv) and polyethylene glycol (800)-acetylene (0.904 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, the solid precipitate was collected, and dried to obtain the non-conjugated fluorescent polymer (LP-7). (See attached instructions) Figure 8 As shown, the emission wavelength of the LP-7 fluorescence test does not shift with the excitation wavelength and is not dependent on the excitation wavelength.
[0057] The chemical formulas involved in the above reaction are as follows: .
[0058] Comparative Example 1
[0059] 1,2-Diaminocyclohexane (0.114 g, 1 equiv) and ethylene glycol dipropynate (0.166 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, and the solid precipitate was collected, dried, and the non-conjugated fluorescent polymer (P-1) was obtained. (See attached instructions.) Figure 9 As shown, the emission wavelength of P-1 fluorescence gradually redshifts with the change of excitation wavelength, exhibiting excitation wavelength dependence.
[0060] The chemical formulas involved in the above reaction are as follows: .
[0061] Comparative Example 2
[0062] 1,4-cyclohexanediamine (0.115 g, 1 equiv) and ethylene glycol dipropynate (0.166 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, and the solid precipitate was collected, dried, and the non-conjugated fluorescent polymer (P-2) was obtained. (See attached instructions.) Figure 10 As shown, the emission wavelength of the P-2 fluorescence test gradually redshifts with the change of the excitation wavelength, exhibiting excitation wavelength dependence.
[0063] The chemical formulas involved in the above reaction are as follows: .
[0064] Comparative Example 3
[0065] 2-Methylaminoethanol (0.075 g, 1 equiv) and ethylene glycol dipropynate (0.166 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, and the solid precipitate was collected, dried, and the non-conjugated fluorescent polymer (P-3) was obtained. (See attached instructions.) Figure 11 As shown, the emission wavelength of the P-3 fluorescence test gradually redshifts with the change of the excitation wavelength, exhibiting excitation wavelength dependence.
[0066] The chemical formulas involved in the above reaction are as follows: .
[0067] Comparative Example 4
[0068] 2-(ethylamino)ethyl-1-ol (0.089 g, 1 equiv) and ethylene glycol dipropynate (0.166 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, the solid precipitate was collected, and dried to obtain the non-conjugated fluorescent polymer (P-4). (See attached instructions) Figure 12 As shown, the emission wavelength of the P-4 fluorescence test gradually redshifts with the change of the excitation wavelength, exhibiting excitation wavelength dependence.
[0069] The chemical formulas involved in the above reaction are as follows: .
[0070] Comparative Example 5
[0071] 2-(tert-butylamino)ethanol (0.117 g, 1 equiv) and ethylene glycol dipropynate (0.166 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, the solid precipitate was collected, and dried to obtain the non-conjugated fluorescent polymer (P-5). (See attached instructions) Figure 13 As shown, the emission wavelength of P-5 fluorescence gradually redshifts with the change of excitation wavelength, exhibiting excitation wavelength dependence.
[0072] The chemical formulas involved in the above reaction are as follows: .
[0073] Comparative Example 6
[0074] 2-Piperidinemethanol (0.115 g, 1 equiv) and ethylene glycol dipropynate (0.166 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, the solid precipitate was collected, and dried to obtain the non-conjugated fluorescent polymer (P-6). (See attached instructions) Figure 14 As shown, the emission wavelength of P-6 fluorescence gradually redshifts with the change of excitation wavelength, exhibiting excitation wavelength dependence.
[0075] The chemical formulas involved in the above reaction are as follows: .
[0076] Comparative Example 7
[0077] 4-Piperidinemethanol (0.115 g, 1 equiv) and ethylene glycol dipropynate (0.166 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, the solid precipitate was collected, and dried to obtain the non-conjugated fluorescent polymer (P-7). (See attached instructions) Figure 15 As shown, the emission wavelength of the P-7 fluorescence test gradually redshifts with the change of the excitation wavelength, exhibiting excitation wavelength dependence.
[0078] The chemical formulas involved in the above reaction are as follows: .
[0079] Comparative Example 8
[0080] 3-Piperidinemethanol (0.115 g, 1 equiv) and polyethylene glycol (2000)-yne (2.104 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the reaction solution was precipitated with n-hexane, the solid precipitate was collected, and dried to obtain the non-conjugated fluorescent polymer (LP-7). (See attached instructions) Figure 16 As shown, the emission wavelength of the LP-7 fluorescence test does not shift with the excitation wavelength and is not dependent on the excitation wavelength.
[0081] The chemical formulas involved in the above reaction are as follows: .
[0082] Comparative Example 9
[0083] 1,3-cyclohexanediol (0.116 g, 1 equiv) and ethylene glycol dipropynate (0.166 g, 1 equiv) were added to a 5 mL single-necked polymerization flask and stirred in air at 25 °C for 24 h. After the reaction was completed, the solid precipitate was collected, dried, and the non-conjugated fluorescent polymer (P-10) was obtained. (See attached instructions.) Figure 17 As shown, the emission wavelength of P-10 fluorescence gradually redshifts with the change of excitation wavelength, exhibiting excitation wavelength dependence.
[0084] The chemical formulas involved in the above reaction are as follows: .
[0085] Specific applications
[0086] Using the fluorescent polymers obtained in Examples 1, 2, and 3 as raw materials, their specific applications are explained.
[0087] Application 1
[0088] The fluorescent polymer obtained in Example 1 has a DMF solution that can be printed on paper and metal. It shows no obvious pattern under visible light, but the pattern is clearly visible under ultraviolet light (as per the instruction manual). Figure 18 It can be used as a security and anti-counterfeiting material.
[0089] Application 2
[0090] The fluorescent polymer obtained in Example 5 was compounded with different metal ions, and the polymer only showed up in Fe... 3+ Fluorescence quenching was observed in the presence of ions, indicating that the polymer can specifically recognize ferric ions (as per the instruction manual). Figure 19 As shown), because Fe The ions possess the largest charge / radius ratio, and their strong interaction with the tertiary amine emitters of the polymer promotes intramolecular charge transfer, leading to fluorescence quenching. Furthermore, the fluorescence intensity exhibits a good linear relationship with the concentration of ferric ions (as per the instruction manual). Figure 20 As shown in the figure, it can accurately quantify ferric ions.
[0091] Application 3
[0092] The fluorescent polymer obtained in Example 5, when used for cell imaging, exhibited green fluorescence only in HeLa cells under excitation wavelengths of 404 nm (blue channel), 480 nm (green channel), and 550 nm (red channel) using a fluorescence microscope. No fluorescence was observed in the blue or red channels (as per the instruction manual). Figure 21(As shown). Bright field refers to the morphology of cells observed under visible light. Under a fluorescence microscope, only blue fluorescent substances can be seen in the blue channel, and only red fluorescent substances can be seen in the red channel. No fluorescent color is seen in the blue or red channels because other fluorescent colors are filtered out. This also shows that the fluorescence emission of the fluorescent polymer obtained in Example 5 is independent of the excitation wavelength and does not change with the excitation wavelength.
[0093] (2) The fluorescent polymer obtained in Example 5 can carry the anticancer drug doxorubicin for drug delivery. The first image on the left shows the green fluorescence of the fluorescent polymer obtained in Example 5 under a fluorescence microscope at an excitation wavelength of 480 nm (as per the instruction manual). Figure 22 As shown), the middle image is the red fluorescence of doxorubicin at an excitation wavelength of 550 nm (as per the instruction manual). Figure 22 As shown in the figure, the fluorescence color of the fluorescent polymer obtained in Example 5 does not change with the excitation wavelength, so using it as a carrier for doxorubicin will not affect the accuracy of experimental observations of doxorubicin distribution. If other fluorescent polymers whose fluorescence emission wavelength depends on the excitation wavelength are used as drug carriers, when the fluorescence color of the fluorescent polymer is the same as the fluorescence color of the drug (for example, when irradiated under a red channel, the fluorescence color of both the fluorescent polymer and the drug is red), it will seriously interfere with the accuracy of experimental observations of the drug delivery process.
[0094] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. A non-conjugated fluorescent polymer independent of excitation wavelength, characterized in that, It is a fluorescent polymer obtained by click polymerization of a secondary amine alcohol or a primary amine monomer and an activated alkynyl monomer. The secondary amine alcohol is 3-hydroxypiperidine or 3-piperidinemethanol, the primary amine monomer is cyclohexane-1,3-diamine or m-phenylenediamine, and the activated alkynyl monomer molecular chain is end-capped with alkynyl groups at both ends.
2. The non-conjugated fluorescent polymer independent of excitation wavelength according to claim 1, characterized in that, The molar ratio of secondary or primary amine monomers to activated acetylene monomers in click polymerization is 1:
1.
3. The non-conjugated fluorescent polymer independent of excitation wavelength according to claim 1, characterized in that, The activated alkyne monomer includes the following general structural formula: ； Formula I; ； Formula II; In the above structural formula, the value of m ranges from 1 to 20.
4. The non-conjugated fluorescent polymer independent of excitation wavelength according to claim 1, characterized in that, The activated alkyne monomer is ethylene glycol dipropynate, 1,4-butanediol dipropynate, 1,6-hexanediol dipropynate, or polyethylene glycol-alkyne.
5. The non-conjugated fluorescent polymer independent of excitation wavelength according to claim 1, characterized in that, The non-conjugated fluorescent polymer includes the following general structural formula: ； Formula I; ； Formula II; ； Formula III; ; Formula IV; ； Formula V; ;Form VI; In the above structural formula, the value of n is determined based on the reaction temperature, reaction time, and specific amount of reactants used in the click reaction, while the value of m is determined based on the chemical structure of the activated acetylene monomer.
6. An in vitro cell fluorescence imaging technique, characterized in that, Using the non-conjugated fluorescent polymer described in any one of claims 1-5 as a traceable fluorescent probe, the drug delivery process within cells is observed, including the escape across the cell membrane, cytoplasm, and endosomes, as well as the entry into the cell nucleus.
7. A fluorescence sensor for detecting metal ions, characterized in that, Using the non-conjugated fluorescent polymer as described in any one of claims 1-5 as the fluorescent probe of the fluorescent sensor, quantitative detection of metal ions in solution is achieved based on the signal generated by the fluorescent probe binding with metal ions, which results in fluorescence quenching or enhancement.