A method for improving two-dimensional polymer fluorescence intensity with excitation wavelength dependence

Abstract

This invention provides a method for improving the fluorescence intensity of a two-dimensional polymer with excitation wavelength dependence, comprising the following steps: (1) adding the two-dimensional polymer with excitation wavelength dependence to an organic solvent and stirring to obtain a homogeneous and transparent solution, adding fluorescent molecules and a catalyst to the solution, and subjecting the two-dimensional polymer with excitation wavelength dependence to an esterification or amidation reaction with the fluorescent molecules; (2) after the reaction is completed, precipitation, dialysis, filtration and drying are performed to obtain the product. This invention introduces traditional fluorescent molecules into the two-dimensional polymer with excitation wavelength dependence to change the molecular aggregation state of the two-dimensional polymer, restricting intramolecular rotation or intramolecular vibration, thereby reducing non-radiative decay, resulting in a significant enhancement of the fluorescence of the two-dimensional polymer with excitation wavelength dependence, achieving the retention of excitation wavelength dependence within a relatively wide excitation wavelength range, enhancing the original blue and green colors, and being able to adjust to produce red fluorescence, with the intensity of red fluorescence also being correspondingly enhanced.

Description

Technical Field

[0001] This invention relates to the field of polymer fluorescent materials technology, specifically to a method for improving the fluorescence intensity of two-dimensional polymers with excitation wavelength dependence. Background Technology

[0002] Fluorescence is the light produced when a molecule is excited by photons, reaching an electronically excited state, and then returns to its ground state. Fluorescent polymer materials emit light through the immobilization effect caused by cross-linking, suppressing the vibration and rotation of the luminescent centers. Fluorescent polymer materials have wide applications in optical devices, microscopic imaging, and biomedical research. However, traditional polymer fluorescent materials have a narrow excitation wavelength range. Different fluorescent materials require specific wavelengths of excitation light to emit light, so different fluorescent materials must be selected to obtain different colors of fluorescence, which limits their application in some areas. In contrast, non-traditional cluster-luminescent materials generally exhibit excitation light source-dependent luminescence behavior. That is, within a certain range, the emitted light gradually redshifts as the excitation light wavelength increases, allowing for the adjustment of different emission colors to meet the needs of more fields. It is worth noting that these non-traditional cluster-luminescent materials typically have complex molecular structures with conjugated groups such as benzene rings, resulting in a relatively narrow range for achieving excitation wavelength dependence. They can usually only produce blue and green fluorescence depending on the excitation wavelength, but it is difficult to produce red fluorescence, and the fluorescence intensity is relatively weak.

[0003] Two-dimensional polymer materials are ordered two-dimensional polymer materials formed by the periodic arrangement of small molecules through non-covalent interactions. Two-dimensional polymers with excitation wavelength dependence refer to those that exhibit wavelength-dependent luminescence behavior over a relatively wide excitation wavelength range due to the aggregation behavior of non-conjugated or conjugated systems with simple molecular structures such as aliphatic chains, heteroatoms, carbonyl groups, and amide groups, but their fluorescence intensity is weak. These two-dimensional polymer materials have advantages such as ultra-high specific surface area and good mechanical properties, but their weak fluorescence intensity limits their application range. Therefore, if we want to widely apply these two-dimensional polymer materials to real life, it is particularly important to enhance their fluorescence intensity, which has practical significance. Summary of the Invention

[0004] The technical problem to be solved by this invention is how to improve the fluorescence intensity of two-dimensional polymers with excitation wavelength dependence.

[0005] The present invention solves the above-mentioned technical problems through the following technical means:

[0006] This invention provides a method for improving the fluorescence intensity of two-dimensional polymers with excitation wavelength dependence, comprising the following steps:

[0007] (1) Add the two-dimensional polymer with excitation wavelength dependence to an organic solvent and stir to obtain a homogeneous and transparent solution. Add fluorescent molecules and a catalyst to the solution and the two-dimensional polymer with excitation wavelength dependence reacts with the fluorescent molecules through esterification or amidation.

[0008] (2) After the reaction is complete, precipitation, dialysis, filtration and drying are performed to obtain the product.

[0009] Beneficial effects: In order to expand the application range of two-dimensional polymers and enable them to be used as fluorescent materials, this invention introduces traditional fluorescent molecules into two-dimensional polymers with excitation wavelength dependence. This is used to change the molecular aggregation state of the two-dimensional polymer, restrict intramolecular rotation or intramolecular vibration, thereby reducing non-radiative decay. This results in a significant enhancement of the fluorescence of the two-dimensional polymer with excitation wavelength dependence, maintaining the excitation wavelength dependence over a relatively wide range, enhancing the original blue and green fluorescence, and being able to modulate red fluorescence with a corresponding increase in red fluorescence intensity.

[0010] Preferably, the wavelength-dependent two-dimensional polymer is prepared by self-assembly of small molecule monomers through non-covalent interactions and contains functional groups capable of undergoing esterification or amidation reactions.

[0011] Preferably, the organic solvent includes one of N-methylpyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, or tetrahydrofuran.

[0012] Preferably, the fluorescent molecule includes one of hydroxypyrene, aminopyrene, sodium fluorescein, or rhodamine B.

[0013] Preferably, the catalyst comprises one of N,N-dimethylaminopyridine or thionyl chloride.

[0014] Preferably, the molar ratio of the fluorescent molecule to the two-dimensional polymer is 1:0.08-0.1.

[0015] Preferably, the molar ratio of the fluorescent molecule to the catalyst is 1:0.1-0.5.

[0016] Preferably, the reaction further includes a coupling agent, wherein the coupling agent is dicyclohexylcarbodiimide.

[0017] Preferably, the molar ratio of the coupling agent to hydroxypyrene and aminopyrene is 1:1.2.

[0018] Preferably, the reaction temperature is 5-25℃ and the reaction time is 12-72h.

[0019] The advantages of this invention are as follows: The two-dimensional polymer with excitation wavelength dependence in this invention exhibits wavelength-dependent luminescence behavior over a relatively wide excitation wavelength range through the aggregation behavior of non-conjugated or conjugated systems with simple molecular structures such as aliphatic chains, heteroatoms, carbonyl groups, or amide groups. It can be tuned to produce three luminescence colors: blue, green, and red, depending on different excitation wavelengths, but its fluorescence intensity is relatively weak. This invention introduces traditional fluorescent molecules into the two-dimensional polymer to change the molecular aggregation state of the two-dimensional polymer through a simple organic chemical reaction, restricting intramolecular rotation or intramolecular vibration, reducing non-radiative decay, and thus retaining the excitation wavelength dependence over a relatively wide excitation wavelength range. It enhances the original blue and green fluorescence and tunes to produce red fluorescence, with a corresponding increase in red fluorescence intensity. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a two-dimensional polymer 2D PAMAD transmission electron microscope from Example 1;

[0021] Figure 2 This is the 1H NMR spectrum of the two-dimensional polymer 2D PAMAD in Example 1 after the fluorescent molecule hydroxypyrene was introduced;

[0022] Figure 3 These are the UV-Vis absorption spectra of the two-dimensional polymer 2D PAMAD before and after the introduction of the fluorescent molecule hydroxypyrene in Example 1; where 3(a) represents the UV-Vis absorption spectrum of the two-dimensional polymer 2D PAMAD; and 3(b) represents the UV-Vis absorption spectrum of the two-dimensional polymer 2D PAMAD after the introduction of the fluorescent molecule hydroxypyrene.

[0023] Figure 4 These are the fluorescence emission spectra of the two-dimensional polymer 2D PAMAD in Example 1 before and after the introduction of the fluorescent molecule hydroxypyrene; wherein Figure 4 (a) shows the fluorescence emission spectrum of the two-dimensional polymer 2D PAMAD; 4(b) shows the fluorescence emission spectrum of the fluorescent molecule hydroxypyrene; Figure 4 (c) shows a comparison of the fluorescence emission spectra of the two-dimensional polymer 2D PAMAD and the two-dimensional polymer 2D PAMAD with the fluorescent molecule hydroxypyrene introduced into it; Figure 4 (d) is a magnified view of the comparison of the fluorescence emission spectra of the two-dimensional polymer 2D PAMAD and the two-dimensional polymer 2D PAMAD with the introduction of the fluorescent molecule hydroxypyrene;

[0024] Figure 5 This is an inverted fluorescence microscope schematic diagram of the solid powder before and after the introduction of the fluorescent molecule hydroxypyrene into the two-dimensional polymer 2D PAMAD in Example 1; wherein Figure 5 (a)(b)(c) show schematic diagrams of the two-dimensional polymer 2D PAMAD in the blue, green and red channels, respectively, using an inverted fluorescence microscope. Figure 5 (d)(e)(f) represent inverted fluorescence microscope diagrams of the two-dimensional polymer 2D PAMAD with the fluorescent molecule hydroxypyrene in the blue, green and red channels;

[0025] Figure 6 This is an inverted fluorescence microscope schematic diagram of the solid powder before and after the introduction of the fluorescent molecule aminopyrene into the two-dimensional polymer 2D PAMAD in Example 2; wherein Figure 6 (a)(b)(c) show schematic diagrams of the two-dimensional polymer 2D PAMAD in the blue, green and red channels, respectively, using an inverted fluorescence microscope. Figure 6 (d)(e)(f) represent inverted fluorescence microscope diagrams of the two-dimensional polymer 2D PAMAD with the fluorescent molecule aminopyrene in the blue, green and red channels;

[0026] Figure 7 This is a schematic diagram of the solid powder before and after the introduction of the fluorescent molecule sodium fluorescein into the two-dimensional polymer 2D PDBA in Example 3, using an inverted fluorescence microscope; whereby... Figure 7 (a)(b)(c) show schematic diagrams of the two-dimensional polymer 2D PDBA in the blue, green and red channels, respectively, using an inverted fluorescence microscope. Figure 7 (d)(e)(f) represent inverted fluorescence microscope diagrams of the two-dimensional polymer 2D PDBA with the fluorescent molecule sodium fluorescein in the blue, green and red channels. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0029] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0030] Example 1

[0031] This embodiment provides a method for improving the fluorescence intensity of two-dimensional polymers with excitation wavelength dependence, specifically including the following steps:

[0032] 1. Preparation of two-dimensional polymers with excitation wavelength dependence

[0033] 12-Aminododecanoic acid was reacted with acrylic acid to generate the amphiphilic monomer acrylamide dodecanoic acid (AMAD). AMAD was added to deionized water, followed by sodium hydroxide, and the mixture was shaken to dissolve and mix thoroughly. Potassium persulfate, a redox initiator, was added to the reaction solution. After three cycles of freezing, vacuuming, and nitrogen purging to remove oxygen, the mixture underwent free radical polymerization at 35°C. The resulting product was then dialyzed and freeze-dried to obtain the wavelength-dependent two-dimensional polymer 2D PAMAD.

[0034] like Figure 1 As shown, the transmission electron microscope (TEM) image of the two-dimensional polymer 2D PAMAD; the ultraviolet-visible absorption spectrum is shown below. Figure 3 As shown in (a), the characteristic peaks of the two-dimensional polymer 2D PAMAD are mainly concentrated around 200 nm; the fluorescence emission spectrum is shown in Figure 1. Figure 4 As shown in (a)(c), by Figure 4 (a) It can be seen that the two-dimensional polymer 2D PAMAD exhibits excitation wavelength dependence, from which... Figure 4 (c) It can be seen that the fluorescence intensity of the two-dimensional polymer 2D PAMAD is relatively weak; a schematic diagram of the two-dimensional polymer 2D PAMAD inverted fluorescence microscope is shown below. Figure 5 As shown in (a)(b)(c), its fluorescence intensity is extremely weak in the blue, green, and red channels. This result is consistent with... Figure 4 (c) Consistent.

[0035] 2. Methods to improve the fluorescence intensity of 2D PAMAD in two-dimensional polymers

[0036] (1) The two-dimensional polymer 2D PAMAD (1000 mg, 3.717 mmol) prepared above was added to a 50 mL polymerization flask, and 25 mL of N-methylpyrrolidone was added at the same time. The mixture was stirred to obtain a homogeneous and transparent solution. Then, fluorescent molecule hydroxypyrene (64.8 mg, 0.297 mmol), N,N-dimethylaminopyridine (3.7 mg, 0.03 mmol), and coupling agent dicyclohexylcarbodiimide (74.2 mg, 0.36 mmol) were added to the solution. The mixture was reacted in a low-temperature reactor (5 °C) in the dark for 72 h.

[0037] (2) After the reaction is complete, the reaction solution is treated and added dropwise to diethyl ether to precipitate the product. The volume ratio of the reaction solution to the precipitant diethyl ether is 1:50. The precipitate is dissolved in NaOH aqueous solution, dialyzed, and then freeze-dried to obtain the product. The specific reaction equation is as follows:

[0038]

[0039] Figure 2 The image shown is the hydrogen nuclear magnetic resonance spectrum of the product in this embodiment. Figure 2It can be seen that the two-dimensional polymer 2D PAMAD introduces 7.8% of the fluorescent molecule hydroxypyrene.

[0040] like Figure 3 As shown, the solution after the reaction was further characterized by ultraviolet-visible absorption spectroscopy (UV-VIS). Compared with the UV-visible absorption spectrum before the reaction, the absorption peak of hydroxypyrene appeared in the wavelength range of 250-400 nm, which further proved that the two-dimensional polymer 2D PAMAD introduced hydroxypyrene.

[0041] The unreacted 2D PAMAD polymer powder and the product powder after the reaction were added to an appropriate amount of water to prepare a 1 mg / mL solution. Further characterization was performed using fluorescence emission spectroscopy. Figure 4 As shown. The two-dimensional polymer 2D PAMAD (as shown) before the reaction. Figure 4 a) Under different excitation wavelengths, it exhibits an excitation wavelength dependence, showing a redshift, i.e., it possesses cluster emission properties; the fluorescence emission spectrum of the fluorescent molecule hydroxypyrene is as follows: Figure 4 As shown in (b), a comparison of fluorescence intensity between the two-dimensional polymer 2D PAMAD with the fluorescent molecule hydroxypyrene and the two-dimensional polymer 2D PAMAD under the same testing conditions is presented (e.g.). Figure 4 c), where Figure 4 (d) is a magnified view of a local area, showing extremely significant fluorescence enhancement.

[0042] like Figure 5 As shown, the two-dimensional polymer 2D PAMAD powder and the product powder after the reaction of the two-dimensional polymer 2DPAMAD were characterized using an inverted fluorescence microscope. Figure 5 As shown in (a)(b)(c), the fluorescence intensity of the two-dimensional polymer 2D PAMAD powder is very weak in the blue, green, and red channels; almost no fluorescence is visible in the figures. Figure 5 As shown in (d)(e)(f), the product powder of the two-dimensional polymer 2D PAMAD reaction has a very strong fluorescence intensity. By comparing (a)(b)(c) with (d)(e)(f), it can be seen that the fluorescence intensity of the product powder of the two-dimensional polymer 2D PAMAD reaction is significantly enhanced, and red fluorescence is regulated, and the intensity of red fluorescence is also correspondingly enhanced.

[0043] Example 2

[0044] This embodiment provides a method for improving the fluorescence intensity of a two-dimensional polymer with excitation wavelength dependence. The two-dimensional polymer with excitation wavelength dependence used in this embodiment is the same as that in Example 1, and the two-dimensional polymer with excitation wavelength dependence is 2D PAMAD.

[0045] 1. Methods to improve the fluorescence intensity of 2D PAMAD in two-dimensional polymers

[0046] (1) The two-dimensional polymer 2D PAMAD (1000 mg, 3.717 mmol) prepared above was added to a 50 mL polymerization flask and 25 mL of N-methylpyrrolidone was added at the same time. The mixture was stirred to obtain a homogeneous and transparent solution. Then, the fluorescent molecule aminopyrene (60.1 mg, 0.297 mmol), N,N-dimethylaminopyridine (3.7 mg, 0.03 mmol), and the coupling agent dicyclohexylcarbodiimide (74.2 mg, 0.36 mmol) were added to the solution and reacted in the dark in a low temperature reactor (5 °C) for 72 h.

[0047] (2) After the reaction is complete, the reaction solution is treated and added dropwise to diethyl ether to precipitate the product. The volume ratio of the reaction solution to the precipitant diethyl ether is 1:50. The precipitate is dissolved in NaOH aqueous solution, dialyzed, and then freeze-dried to obtain the product. The specific reaction equation is as follows:

[0048]

[0049] like Figure 6 As shown, the two-dimensional polymer 2D PAMAD powder and the product powder after the reaction of the two-dimensional polymer 2DPAMAD were characterized using an inverted fluorescence microscope. Figure 6 As shown in (a)(b)(c), the fluorescence intensity of the two-dimensional polymer 2D PAMAD powder is very weak in the blue, green, and red channels; almost no fluorescence is visible in the figures. Figure 6 As shown in (d)(e)(f), the product powder of the two-dimensional polymer 2D PAMAD reaction has a very strong fluorescence intensity. By comparing (a)(b)(c) with (d)(e)(f), it can be seen that the fluorescence intensity of the product powder of the two-dimensional polymer 2D PAMAD reaction is significantly enhanced, and red fluorescence is regulated, and the intensity of red fluorescence is also correspondingly enhanced.

[0050] Example 3

[0051] This embodiment provides a method for improving the fluorescence intensity of two-dimensional polymers with excitation wavelength dependence, specifically including the following steps:

[0052] 1. Preparation of two-dimensional polymers with excitation wavelength dependence

[0053] 3,5-Diaminobenzoic acid (1000 mg, 6.6 mmol) was dissolved in 80 mL of water, and potassium carbonate (18.2 g, 131.6 mmol) and 80 mL of ethyl acetate were added. After stirring and dissolving at 5-10 °C, acryloyl chloride (1.86 mL, 26.4 mmol) was added dropwise, and the mixture was reacted at room temperature for 2 h. After the reaction was completed, the organic layer was removed, the precipitate was acidified with dilute hydrochloric acid, dissolved in ethyl acetate, dried over magnesium sulfate, filtered, and rotary evaporated to obtain a large amount of solid 3,5-diacrylamidobenzoic acid, which is the DBA monomer. 200 mL gDBA monomer molecules were added to 50 mL of deionized water and ultrasonically dispersed for 20 min to obtain a grayish-purple suspension. Then, 96.6 μL of the organic base 1,1,3,3-tetramethylguanidine was added, and the grayish-purple suspension immediately became clear and transparent, thus obtaining a two-dimensional supramolecular solution. Under nitrogen protection, 8.4 mg of potassium persulfate was added as an initiator, and the polymerization was carried out by freeze-evacuation-thawing at a polymerization temperature of 70 °C. After polymerization, the solution was dialyzed with deionized water, and the dialyzed solution was acidified, filtered, and freeze-dried to obtain the two-dimensional polymer 2D PDBA with excitation wavelength dependence.

[0054] 2. Methods to improve the fluorescence intensity of 2D polymer PDBA

[0055] (1) The two-dimensional polymer 2D PDBA (100 mg, 0.385 mmol) prepared above was added to a 50 mL polymerization flask, and 20 mL of tetrahydrofuran was added at the same time. After stirring evenly, thionyl chloride (9.2 mg, 0.077 mmol) was added to the solution, and the mixture was refluxed at 80 °C for 4 h. After the reaction was completed, sodium fluorescein (14.7 mg, 0.039 mmol) was added and the mixture was reacted at room temperature for 12 h.

[0056] (2) After the reaction is complete, the reaction solution is treated by first acidifying it with hydrochloric acid, then adding it dropwise to water to precipitate the product. The volume ratio of the reaction solution to water is 1:5. The precipitate is dissolved in KOH aqueous solution, dialyzed, and then freeze-dried to obtain the product. The specific reaction equation is as follows:

[0057]

[0058] like Figure 7 As shown, the two-dimensional polymer 2D PDBA powder and the product powder after the reaction of the two-dimensional polymer 2D PDBA were characterized using an inverted fluorescence microscope. Figure 7 As shown in (a)(b)(c), the fluorescence intensity of the two-dimensional polymer 2D PDBA powder is weak in the blue, green, and red channels; only a small amount of fluorescence can be observed in the figure. Figure 7As shown in (d)(e)(f), the fluorescence intensity of the product powder after the reaction of the two-dimensional polymer 2D PDBA is very strong. By comparing (a)(b)(c) with (d)(e)(f), it can be seen that the fluorescence intensity of the product powder after the reaction of the two-dimensional polymer 2D PDBA is significantly enhanced, and red fluorescence is regulated, and the intensity of red fluorescence is also correspondingly enhanced.

[0059] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the fluorescence intensity of a two-dimensional polymer with excitation wavelength dependence, characterized in that, Includes the following steps: (1) Add the two-dimensional polymer with excitation wavelength dependence to an organic solvent and stir to obtain a homogeneous and transparent solution. Add fluorescent molecules and a catalyst to the solution. The two-dimensional polymer with excitation wavelength dependence reacts with the fluorescent molecules through esterification or amidation. The fluorescent molecules include one of hydroxypyrene, aminopyrene, sodium fluorescein or rhodamine B. The wavelength-dependent two-dimensional polymer was obtained by the following method: 12-aminododecanoic acid was reacted with acrylic acid to generate the amphiphilic monomer acrylamide dodecanoic acid, which was added to water, followed by the addition of sodium hydroxide and mixing thoroughly. Potassium persulfate was then added, and the mixture was deoxygenated after three cycles of freezing-vacuuming-nitrogen purging. Free radical polymerization was then carried out at 35°C, followed by dialyzing and freeze-drying to obtain the wavelength-dependent two-dimensional polymer. Alternatively, 3,5-diaminobenzoic acid was dissolved in water, potassium carbonate and ethyl acetate were added and stirred until dissolved, and acryloyl chloride was added dropwise for a reaction at room temperature. After the reaction, the organic layer was removed, the precipitate was acidified with dilute hydrochloric acid, dissolved in ethyl acetate, dried with magnesium sulfate, filtered, and rotary evaporated to obtain the DBA monomer. The DBA monomer molecules were added to water and ultrasonically dispersed to obtain a grayish-purple suspension, followed by the addition of an organic base of 1,1,3... 3-Tetramethylguanidine was used to obtain a two-dimensional supramolecular solution. Under nitrogen protection, potassium persulfate was added, and a freeze-evacuation-thawing polymerization reaction was carried out. After the polymerization was completed, the solution was dialyzed, and the dialyzed solution was acidified, filtered, and freeze-dried to obtain a two-dimensional polymer with excitation wavelength dependence. (2) After the reaction is completed, the reaction solution is precipitated, dialyzed and freeze-dried to obtain the product.

2. The method for improving the fluorescence intensity of a two-dimensional polymer with excitation wavelength dependence according to claim 1, characterized in that, The organic solvent includes one of N-methylpyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, or tetrahydrofuran.

3. The method for improving the fluorescence intensity of a two-dimensional polymer with excitation wavelength dependence according to claim 1, characterized in that, The catalyst includes one of N,N-dimethylaminopyridine or thionyl chloride.

4. The method for improving the fluorescence intensity of a two-dimensional polymer with excitation wavelength dependence according to claim 1, characterized in that, The molar ratio of the fluorescent molecule to the two-dimensional polymer is 1:0.08-0.

1.

5. The method for improving the fluorescence intensity of a two-dimensional polymer with excitation wavelength dependence according to claim 1, characterized in that, The molar ratio of the fluorescent molecule to the catalyst is 1:0.1-0.

5.

6. The method for improving the fluorescence intensity of two-dimensional polymers with excitation wavelength dependence according to claim 1, characterized in that, The esterification or amidation reaction further includes a coupling agent, wherein the coupling agent is dicyclohexylcarbodiimide.

7. The method for improving the fluorescence intensity of a two-dimensional polymer with excitation wavelength dependence according to claim 6, characterized in that, The molar ratio of the coupling agent to the fluorescent molecule is 1:1.

2.

8. The method for improving the fluorescence intensity of a two-dimensional polymer with excitation wavelength dependence according to claim 1, characterized in that, The reaction temperature is 5-25℃ and the time is 12-72h.

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