Method for improving fluorescence intensity of excitation wavelength dependent two-dimensional polymer

Abstract

The invention provides a method for improving the fluorescence intensity of a two-dimensional polymer with excitation wavelength dependence, which comprises the following steps: (1) adding the two-dimensional polymer with excitation wavelength dependence into an organic solvent, stirring to obtain a uniform and transparent solution, adding fluorescent molecules and a catalyst into the uniform and transparent solution, and stirring to obtain a transparent solution; carrying out esterification or amidation reaction on the two-dimensional polymer with excitation wavelength dependence and fluorescent molecules; and (2) after the reaction is finished, precipitating, dialyzing, filtering and drying to obtain the product. Traditional fluorescent molecules are introduced into the two-dimensional polymer with excitation wavelength dependence to change the molecular aggregation state of the two-dimensional polymer and limit intramolecular rotation or intramolecular vibration, so that non-radiation attenuation is reduced, fluorescence of the two-dimensional polymer with excitation wavelength dependence is remarkably enhanced, and the fluorescence intensity of the two-dimensional polymer with excitation wavelength dependence is improved. According to the present invention, the excitation wavelength dependence is maintained in the relatively wide excitation wavelength range, the original blue and green are enhanced, the red fluorescence can be obtained through adjustment, and the red fluorescence intensity is correspondingly enhanced;

Description

Technical Field

[0001] The invention relates to the technical field of polymer fluorescent materials, and in particular to a method for improving the fluorescence intensity of a two-dimensional polymer with excitation wavelength dependence. Background Art

[0002] Fluorescence is the light produced by photons exciting molecules to reach an electronic excited state and then return to the ground state. Fluorescent polymer materials emit light through the fixation effect produced by cross-linking, which inhibits the vibration and rotation of the luminescent center and then emits light. Fluorescent polymer materials are widely used in optical devices, microscopic imaging, biomedical research, etc. However, the excitation wavelength range of traditional polymer fluorescent materials is very narrow. Different fluorescent materials must be excited with a specific wavelength of light source to emit light. Therefore, different fluorescent materials must be selected to obtain different colors of fluorescence, which limits its application in some aspects. However, non-traditional cluster luminescent materials generally exhibit luminescence behavior dependent on the excitation light source, that is, within a certain range, as the wavelength of the excitation light source increases, the emitted light will gradually redshift, and different luminescent colors can be adjusted as needed to meet the needs of more fields. It is worth noting that such non-traditional cluster luminescent materials usually have a complex molecular structure system of conjugated groups such as benzene rings, and the range of excitation wavelength dependence is still relatively narrow. Usually, only blue and green fluorescence can be adjusted according to different excitation wavelengths, but it is difficult to adjust red fluorescence, and the fluorescence intensity is weak.

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

[0004] The technical problem to be solved by the present invention is how to improve the fluorescence intensity of a two-dimensional polymer having excitation wavelength dependence.

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

[0006] The present invention provides a method for improving the fluorescence intensity of a two-dimensional polymer having excitation wavelength dependence, comprising the following steps:

[0007] (1) adding a two-dimensional polymer having excitation wavelength dependence into an organic solvent and stirring to obtain a uniform transparent solution, adding a fluorescent molecule and a catalyst thereto, and subjecting the two-dimensional polymer having excitation wavelength dependence to an esterification or amidation reaction with the fluorescent molecule;

[0008] (2) After the reaction is completed, the product is obtained by precipitation, dialysis, filtration and drying.

[0009] Beneficial effects: In order to expand the application scope of two-dimensional polymers and enable them to be used as fluorescent materials, the present invention introduces traditional fluorescent molecules into two-dimensional polymers with excitation wavelength dependence, which are used to change the molecular aggregation state of the two-dimensional polymers, restrict intramolecular rotation or intramolecular vibration, thereby reducing non-radiative attenuation, resulting in significant enhancement of the fluorescence of the two-dimensional polymer with excitation wavelength dependence, retaining the excitation wavelength dependence within a relatively wide excitation wavelength range, enhancing the original blue and green, and being able to adjust red fluorescence, and the red fluorescence intensity is correspondingly enhanced.

[0010] Preferably, the two-dimensional polymer with excitation wavelength dependence is prepared by self-assembly of small molecular monomers through non-covalent interactions, and contains functional groups capable of 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 comprises a coupling agent, and the coupling agent is dicyclohexylcarbodiimide.

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

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

[0019] The advantages of the present invention are as follows: the two-dimensional polymer with excitation wavelength dependence in the present invention exhibits wavelength-dependent luminescence behavior within a relatively wide excitation wavelength range through the aggregation behavior of a non-conjugated system or a conjugated system with simple molecular structures such as a fatty chain, a heteroatom, a carbonyl group or an amide group, and can adjust three luminescent colors of blue, green and red according to different excitation wavelengths, but its fluorescence intensity is relatively weak; the present 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, restricts intramolecular rotation or intramolecular vibration, reduces non-radiative attenuation, and achieves retention of excitation wavelength dependence within a relatively wide excitation wavelength range, enhances the original blue and green fluorescence, and adjusts the red fluorescence, and the red fluorescence intensity is also correspondingly enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0021] Figure 2 is the nuclear magnetic resonance hydrogen spectrum of the two-dimensional polymer 2D PAMAD in Example 1 after the fluorescent molecule hydroxypyrene is introduced;

[0022] Figure 3 3(a) shows the ultraviolet-visible absorption spectrum of the two-dimensional polymer 2D PAMAD before and after the fluorescent molecule hydroxypyrene is introduced into the two-dimensional polymer 2D PAMAD in Example 1; 3(b) shows the ultraviolet-visible absorption spectrum of the two-dimensional polymer 2D PAMAD after the fluorescent molecule hydroxypyrene is introduced into the two-dimensional polymer 2DPAMAD;

[0023] Figure 4 is the fluorescence emission spectrum 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 2D polymer 2D PAMAD; 4(b) shows the fluorescence emission spectrum of fluorescent molecule hydroxypyrene; Figure 4 (c) shows the comparison of fluorescence emission spectra of two-dimensional polymer 2D PAMAD and two-dimensional polymer 2D PAMAD with the introduction of fluorescent molecule hydroxypyrene; Figure 4 (d) A partial enlarged view showing 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 Schematic diagram of an inverted fluorescence microscope of solid powder before and after the introduction of fluorescent molecule hydroxypyrene into the two-dimensional polymer 2D PAMAD in Example 1; wherein Figure 5 (a)(b)(c) Schematic diagrams of inverted fluorescence microscopy showing 2D polymer 2D PAMAD in blue, green and red channels respectively; Figure 5 (d)(e)(f) Schematic diagram of inverted fluorescence microscopy showing the introduction of fluorescent molecule hydroxypyrene into the two-dimensional polymer 2D PAMAD in blue, green and red channels;

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

[0026] Figure 7 is a schematic diagram of an inverted fluorescence microscope of the solid powder of the two-dimensional polymer 2D PDBA in Example 3 before and after the introduction of the fluorescent molecule sodium fluorescein; wherein Figure 7 (a)(b)(c) Schematic diagrams of inverted fluorescence microscopy showing the two-dimensional polymer 2D PDBA in blue, green and red channels respectively; Figure 7 (d)(e)(f) Schematic diagram of inverted fluorescence microscopy showing the blue, green and red channels of the two-dimensional polymer 2D PDBA with the fluorescent molecule sodium fluorescein introduced into it. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0029] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0030] Example 1

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

[0032] 1. Preparation of 2D polymers with excitation wavelength dependence

[0033] 12-aminododecanoic acid reacts with acrylic acid to generate the amphiphilic monomer acrylamide dodecanoic acid AMAD. Add it into deionized water, then add sodium hydroxide, shake and dissolve and mix evenly, add redox initiator potassium persulfate into the above reaction solution, deoxygenate after freezing-vacuuming-nitrogen filling for 3 cycles, perform free radical polymerization at 35°C, and then dialyze and freeze-dry to obtain a two-dimensional polymer 2D PAMAD with excitation wavelength dependence.

[0034] like Figure 1 As shown, the transmission electron microscope TEM image of the two-dimensional polymer 2D PAMAD; the UV-visible absorption spectrum is shown in Figure 3 As shown in (a), the characteristic peak of the two-dimensional polymer 2D PAMAD is mainly concentrated around 200nm; the fluorescence emission spectrum is shown in Figure 4 As shown in (a)(c), Figure 4 (a) It can be seen that the two-dimensional polymer 2D PAMAD has excitation wavelength dependence, which is Figure 4 (c) It can be seen that the fluorescence intensity of the two-dimensional polymer 2D PAMAD is weak; the schematic diagram of the two-dimensional polymer 2D PAMAD inverted fluorescence microscope is as follows Figure 5 As shown in (a)(b)(c), the fluorescence intensity is extremely weak in the blue, green and red channels. Figure 4 (c)Consistency.

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

[0036] (1) The two-dimensional polymer 2D PAMAD (1000 mg, 3.717 mmol) prepared above was added into a 50 mL polymerization bottle, and 25 mL of N-methylpyrrolidone was added at the same time, and stirred to obtain a uniform and transparent solution. Then, fluorescent molecules 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 into the solution, and the mixture was reacted in a low temperature reactor (5°C) in the dark for 72 h.

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

[0038]

[0039] Figure 2 is the hydrogen nuclear magnetic resonance spectrum of the product of this embodiment, Figure 2It can be seen that the two-dimensional polymer 2D PAMAD introduced 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 between the wavelength of 250-400nm, which further proved that the two-dimensional polymer 2D PAMAD introduced hydroxypyrene.

[0041] The two-dimensional polymer 2D PAMAD powder before the reaction and the product powder after the two-dimensional polymer 2D PAMAD reaction were added with an appropriate amount of water to prepare a 1 mg / mL solution, and further characterized by fluorescence emission spectroscopy, such as Figure 4 As shown. The two-dimensional polymer 2D PAMAD before reaction ( Figure 4 a) Under different excitation wavelengths, it shows excitation wavelength dependence and red shift, that is, it has cluster emission properties; the fluorescence emission spectrum of the fluorescent molecule hydroxypyrene is as follows Figure 4 As shown in (b), the fluorescence intensity comparison diagram of the two-dimensional polymer 2D PAMAD introduced with the fluorescent molecule hydroxypyrene and the two-dimensional polymer 2D PAMAD under the same test conditions (as shown in Figure 4 c), where Figure 4 (d) is a local magnified image, showing a very significant fluorescence enhancement.

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

[0043] Example 2

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

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

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

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

[0048]

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

[0050] Example 3

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

[0052] 1. Preparation of 2D polymers with excitation wavelength dependence

[0053] 3,5-Diaminobenzoic acid (1000 mg, 6.6 mmol) was dissolved in 80 mL of water, potassium carbonate (18.2 g, 131.6 mmol) and 80 mL of ethyl acetate were added, and after stirring at 5-10°C for dissolution, acryloyl chloride (1.86 mL, 26.4 mmol) was added dropwise and reacted at room temperature for 2 h. After the reaction, the organic layer was removed, the precipitate was acidified with dilute hydrochloric acid, and then dissolved with ethyl acetate, dried and filtered with magnesium sulfate, and a large amount of 3,5-diacrylamidebenzoic acid solid was obtained by rotary evaporation, which was DBA monomer. 200 m The gDBA monomer molecule was added to 50 mL of deionized water and ultrasonically dispersed for 20 minutes to obtain a gray-purple suspension. Subsequently, 96.6 μL of organic base 1,1,3,3-tetramethylguanidine was added, and the gray-purple suspension immediately became clear and transparent, thereby obtaining a two-dimensional supramolecular solution. Under nitrogen protection, 8.4 mg of potassium persulfate was added as an initiator, and a freeze-pump-thaw polymerization operation was performed. The polymerization temperature was 70°C. After the polymerization, the solution was dialyzed with deionized water. The dialyzed solution was acidified, filtered, and then freeze-dried to obtain a two-dimensional polymer 2D PDBA with excitation wavelength dependence.

[0054] 2. Methods for improving the fluorescence intensity of 2D PDBA

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

[0056] (2) After the reaction is completed, the reaction solution is treated by first adding hydrochloric acid to acidify it, and then adding it dropwise to water to precipitate it. The volume ratio of the reaction solution to water is 1:5. The precipitate is dissolved with KOH aqueous solution, dialyzed and 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 2DPDBA were characterized using an inverted fluorescence microscope. Figure 7 (a)(b)(c) shows that the fluorescence intensity of the two-dimensional polymer 2D PDBA powder in the blue, green and red channels is weak, and a little fluorescence can be seen in the figure; Figure 7(d)(e)(f) shows that the fluorescence intensity of the powder product 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 powder product after the reaction of the two-dimensional polymer 2D PDBA is significantly enhanced, and red fluorescence is adjusted, and the red fluorescence intensity is also enhanced accordingly.

[0059] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions 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 having excitation wavelength dependence, characterized in that: The following steps are involved: (1) adding a two-dimensional polymer having excitation wavelength dependence into an organic solvent and stirring to obtain a uniform transparent solution, adding a fluorescent molecule and a catalyst thereto, and subjecting the two-dimensional polymer having excitation wavelength dependence to an esterification or amidation reaction with the fluorescent molecule; (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 having excitation wavelength dependence according to claim 1, characterized in that: The two-dimensional polymer with excitation wavelength dependence is prepared by self-assembly of small molecular monomers through non-covalent interaction, and contains functional groups capable of esterification or amidation reaction.

3. The method for improving the fluorescence intensity of a two-dimensional polymer having 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.

4. The method for improving the fluorescence intensity of a two-dimensional polymer having excitation wavelength dependence according to claim 1, characterized in that: The fluorescent molecule includes one of hydroxypyrene, aminopyrene, sodium fluorescein or rhodamine B.

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

6. The method for improving the fluorescence intensity of a two-dimensional polymer having 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.

7. The method for improving the fluorescence intensity of a two-dimensional polymer having 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.

8. The method for improving the fluorescence intensity of a two-dimensional polymer having excitation wavelength dependence according to claim 3, characterized in that: The reaction further comprises a coupling agent, and the coupling agent is dicyclohexylcarbodiimide.

9. The method for improving the fluorescence intensity of a two-dimensional polymer having excitation wavelength dependence according to claim 8, characterized in that: The molar ratio of the coupling agent to the fluorescent molecule is 1:1.

2.

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

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