Preparation method and product of unconventional full-color luminescent polymer coupled with dopamine and polymer

Abstract

Disclosed are a method for preparing an unconventional full-color luminescent polymer coupled with dopamine and a polymer, and a product thereof. The method uses dopamine without fluorescence as an end group for coupling with the polymer, utilizes acrylic anhydride to react with dopamine, and uses acryloyl groups to protect the amino groups of the dopamine, thereby inhibiting dopamine self-polymerization. The double bond of the acryloyl group reacts with the amino group at the end of the polymer to couple the dopamine to the end of the polymer, and uses the polymer as a skeleton to inhibit π-π stacking of dopamine. Simultaneously, dopamine is used as an end group to regulate the fluorescence of the polymer, thereby obtaining a polymer with a clear structure, adjustable fluorescence, and full-color luminescence.

Description

Technical Field

[0001] The present invention belongs to the technical field of novel organic fluorescent materials, and in particular relates to a preparation method and product of an unconventional full-color luminescent polymer coupled with dopamine and a polymer. Background Art

[0002] Unconventional luminescent materials refer to new fluorescent materials that do not have the conjugated structure required by traditional luminescent materials, but only contain electron-rich heteroatoms or unsaturated bonds and have fluorescent properties. Due to their good biocompatibility, photostability, and easy synthesis, they have been widely studied in recent years. Polymers, as a multifunctional material, were accidentally discovered at the end of the last century to have certain photoluminescent properties under ultraviolet light excitation, such as polyamide, polyethyleneimine, polylysine, polysiloxane, etc. Subsequently, a large number of studies have explored the mechanism of their fluorescence generation and the regulation of fluorescence.

[0003] Extensive research has been conducted on the regulation of polymer fluorescence, including the introduction of traditional fluorescent groups, polymer carbonization, end-group modification, oxidation, and structural crosslinking. These methods all have definite effects on the fluorescence intensity and luminescence range of polymers, but they also present varying degrees of drawbacks. For example, the introduction of traditional fluorophores can mask the intrinsic fluorescence behavior of the polymer, the structure of the fluorescent nanoparticles obtained after carbonization is unclear, the fluorescence intensity is enhanced to a certain extent after end-group modification, but the luminescence range is limited to the short wavelength region, the fluorescence of the polymer after oxidation does not necessarily change, and the microstructure is uncontrollable during structural crosslinking. These methods have greatly limited the development and application of fluorescent polymers. The successful development of novel fluorescent materials with well-defined structures, tunable fluorescence, good biocompatibility, and full-color luminescence remains elusive. Summary of the Invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0005] As one aspect of the present invention, the present invention provides a method for preparing an unconventional full-color luminescent polymer coupled with dopamine and a polymer, which comprises the following steps:

[0006] (1) Preparation of DA monomer: dopamine hydrochloride and triethylamine were added to ultra-dry pyridine, and after deoxygenation, acrylic anhydride diluted with ultra-dry tetrahydrofuran was added dropwise, stirred at 0°C, and gradually returned to room temperature after the addition was completed, and stirred overnight; after the reaction was completed, the obtained reaction solution was vacuum dried and concentrated, acetone was added to dissolve the residue, and the insoluble components were removed by filtration. After the filtrate was concentrated to remove the acetone, deionized water and ethyl acetate were added and stirred, and the organic phase was washed, dried over anhydrous sodium sulfate, and purified by column chromatography;

[0007] (2) Preparation of polymer HPAA: N,N′-methylenebisacrylamide and (2-aminoethyl)piperazine were dissolved in methanol / water and reacted at 50°C in the dark for 5 days after deoxygenation. After the reaction was complete, (2-aminoethyl)piperazine was slowly added dropwise and capped at 37°C for 8 hours. The resulting reaction solution was then added dropwise to acetone for precipitation.

[0008] (3) Preparation of polymer HPDA: The HPAA and DA were dissolved in dimethyl sulfoxide / water solvent, and reacted at 50°C for 2 days after deoxygenation. After the reaction was completed, the reaction solution was concentrated in vacuo and added dropwise to acetone for precipitation;

[0009] (4) Preparation of polymer PLDA: Weigh polylysine and DA and dissolve them in methanol / water. Then add sodium hydroxide solution to adjust the pH to 8-9. After deoxygenation, react at 50°C in the dark for 2 days. After the reaction is completed, take out the reaction solution and let it cool to room temperature. Then vacuum dry and concentrate to remove methanol. The concentrated reaction solution is added dropwise into acetone / ether for precipitation.

[0010] As a preferred embodiment of the method for preparing the unconventional full-color luminescent polymer coupled with dopamine and polymer according to the present invention: in step (1), the molar ratio of dopamine hydrochloride to triethylamine is 1:2.

[0011] As a preferred embodiment of the method for preparing the unconventional full-color luminescent polymer coupled with dopamine and polymer according to the present invention: in step (1), 36.9 mmol of dopamine hydrochloride is placed in a three-necked flask, 80 mL of ultra-dry pyridine and 73.8 mmol of triethylamine are added, and the mixture is deoxygenated by bubbling with argon for 10 minutes under slow stirring, 36.9 mmol of acrylic anhydride is diluted with 10 mL of ultra-dry tetrahydrofuran and placed in a dropping funnel, and argon is bubbled for 1 minute, the entire reaction system is sealed and placed in an ice bath at 0°C and stirred for 5 minutes, and then stirred. Open the dropping funnel and adjust the rate to 2s / drop to allow acrylic anhydride to drip into the three-necked flask. After the addition is completed, gradually return to room temperature and stir overnight. After the reaction is completed, the reaction solution is vacuum dried and concentrated, 50mL of acetone is added to dissolve the residue, and the insoluble components are removed by filtration. After the filtrate is concentrated to remove acetone, 50mL of deionized water and 75mL of ethyl acetate are added and stirred for 1h. The aqueous phase is separated and removed. The organic phase is washed twice with 1M hydrochloric acid solution and twice with concentrated brine, and then dried over anhydrous sodium sulfate and concentrated to obtain a light yellow viscous liquid, which is purified by column chromatography to obtain a white powdery solid.

[0012] As a preferred embodiment of the method for preparing the unconventional full-color luminescent polymer coupled with dopamine and polymer described in the present invention: in step (2), 616.68 mg of N, N′-methylenebisacrylamide was weighed and dissolved in 8 mL of a methanol / water mixed solution. After ultrasonic dissolution, 258.4 mg of (2-aminoethyl) piperazine was added, and argon was bubbling for deoxygenation for 1 minute, followed by reaction at 50° C. in the dark for 2 days. After the reaction, the reaction solution was taken out and cooled to room temperature, and 361.7 mg of (2-aminoethyl) piperazine was slowly added dropwise, and end-capping was carried out at 37° C. for 8 hours. After end-capping, the reaction solution was added dropwise into acetone for precipitation. After precipitation, the solution was washed three times with acetone and vacuum dried to obtain a light yellow foamy solid.

[0013] As a preferred solution of the method for preparing the unconventional full-color luminescent polymer coupled with dopamine and polymer according to the present invention: in step (2), the volume ratio of methanol to water in the methanol / water mixed solution is 7:3.

[0014] As a preferred embodiment of the method for preparing the unconventional full-color luminescent polymer coupled with dopamine and polymer according to the present invention: in step (3), 100 mg of HPAA is weighed and dissolved in 3 mL of a dimethyl sulfoxide / water mixed solvent, 50 mg of DA is added after dissolution, and the mixture is subjected to argon bubbling for deoxygenation and reacted at 50° C. for 2 days. After the reaction is completed, the reaction solution is vacuum concentrated, and the reaction solution is dropwise added into acetone for precipitation. After the precipitation is completed, the mixture is washed with acetone and vacuum dried to obtain a brown powder.

[0015] As a preferred embodiment of the method for preparing the unconventional full-color luminescent polymer coupled with dopamine and polymer according to the present invention: in step (3), the volume ratio of dimethyl sulfoxide to water in the dimethyl sulfoxide / water mixed solvent is 7:3.

[0016] As a preferred embodiment of the method for preparing the unconventional full-color luminescent polymer coupled with dopamine and polymer described in the present invention: in step (4), 100 mg of polylysine is weighed and dissolved in 3 mL of a methanol / water mixed solvent with a volume ratio of 7:3, and then 2 mL of sodium hydroxide solution is added, the pH is adjusted to 8-9, and after adding 100 mg of DA, argon is bubbled for deoxygenation for 1 minute, and the reaction is carried out at 50°C in the dark for 2 days; after the reaction is completed, the reaction solution is taken out and allowed to cool to room temperature, vacuum dried and concentrated to remove methanol, and the concentrated reaction solution is dripped dropwise into an acetone / ether mixed solution with a volume ratio of 3:1 to precipitate. After the precipitation is completed, the precipitate is redissolved with 0.8 mL of methanol and dripped into acetone for secondary precipitation, finally obtaining a beige powdery solid.

[0017] The beneficial effects of the present invention include: using dopamine without fluorescence as an end group to couple with a polymer, utilizing acrylic anhydride to react with dopamine, protecting the amino group of dopamine with an acryloyl group, thereby inhibiting dopamine self-polymerization, and coupling dopamine to the polymer end through a Michael addition reaction between the double bond of the acryloyl group and the amino group at the end of the polymer. The polymer is used as a skeleton to inhibit the π-π stacking of dopamine, and at the same time, the fluorescence of the polymer is regulated by using dopamine as an end group, thereby obtaining a polymer with a clear structure, adjustable fluorescence, and full-color luminescence. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0019] Figure 1 This is the DA NMR spectrum.

[0020] Figure 2 This is the HPAA NMR spectrum.

[0021] Figure 3 This is the HPDA NMR spectrum.

[0022] Figure 4 It is the PLL nuclear magnetic spectrum.

[0023] Figure 5 This is the PLDA NMR spectrum.

[0024] Figure 6 is the DA fluorescence emission spectrum.

[0025] Figure 7 is the DA fluorescence excitation spectrum.

[0026] Figure 8 is the DA excitation-emission matrix spectrum.

[0027] Figure 9 is the fluorescence emission spectrum of HPAA.

[0028] Figure 10 is the fluorescence excitation spectrum of HPAA.

[0029] Figure 11 is the HPAA excitation-emission matrix spectrum.

[0030] Figure 12 is the fluorescence emission spectrum of HPDA.

[0031] Figure 13 is the HPDA fluorescence excitation spectrum.

[0032] Figure 14 is the HPDA excitation-emission matrix spectrum.

[0033] Figure 15 is the PLL fluorescence emission spectrum.

[0034] Figure 16 is the PLL fluorescence excitation spectrum.

[0035] Figure 17 is the PLL excitation-emission matrix spectrum.

[0036] Figure 18 is the PLL-DA fluorescence emission spectrum.

[0037] Figure 19 is the PLL-DA fluorescence excitation spectrum.

[0038] Figure 20 is the PLL-DA excitation-emission matrix spectrum. DETAILED DESCRIPTION

[0039] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with specific embodiments.

[0040] Example 1: Synthesis of DA monomer

[0041] Step S1, preparation of DA monomer: dopamine hydrochloride (7 g, 36.9 mmol, 1 eq) was placed in a 250 mL three-necked flask, and ultra-dry pyridine (80 mL) and triethylamine (7.47 g, 73.8 mmol, 2 eq) were added. The mixture was deoxygenated by bubbling with argon for 10 min under slow stirring. Acrylic anhydride (4.66 g, 36.9 mmol, 1 eq) was diluted with ultra-dry tetrahydrofuran (THF, 10 mL) and placed in a dropping funnel. Argon was bubbled for 1 min. The reaction system was sealed and placed in an ice bath at 0°C and stirred for 5 min. The dropping funnel was opened and the rate was adjusted to Acrylic anhydride was added dropwise to the flask at a rate of 2s / drop. After the addition was complete, the mixture was gradually returned to room temperature and stirred overnight. After the reaction was complete, the reaction solution was vacuum dried and concentrated. 50 mL of acetone was added to dissolve the residue, and the insoluble components were removed by filtration. The filtrate was concentrated to remove the acetone, and 50 mL of deionized water and 75 mL of ethyl acetate were added and stirred for 1 hour. The aqueous phase was separated and removed. The organic phase was washed twice with 1M hydrochloric acid solution and twice with concentrated brine, dried over anhydrous sodium sulfate, and concentrated to obtain a light yellow viscous liquid. Purification by column chromatography (dichloromethane / methanol, 1 / 40, v / v) gave 2.2 g of a white powdery solid in a yield of 28.6%. The reaction formula is as follows:

[0042]

[0043] Figure 1 is the H NMR spectrum of DA in Example 1 of the present invention, such as Figure 1 As shown, DA 1 H NMR (600MHz, DMSO-d6): δ 8.74 (s, 1H), 8.64 (s, 1H), 8.12 (s, 1H), 6.63 (d, J = 7.9Hz, 1H), 6.58 (d, J = 2.1Hz, 1H), 6.43 (dd, J = 7.9, 2.1Hz, 1 H), 6.19 (dd, J=17.1, 10.2Hz, 1H), 6.06 (dd, J=17.1, 2.2Hz, 1H), 5.56 (dd, J=10.2, 2.2Hz, 1H), 3.28-3.23 (m, 2H), 2.55 (t, J=7.5Hz, 2H).

[0044] Example 2: Synthesis of polymer HPAA

[0045] Step S2, Preparation of Polymer HPAA: 616.68 mg (4 mmol, 2 eq) of N,N′-methylenebisacrylamide (MBA) was weighed and dissolved in 8 mL of a methanol / water (7 / 3, v / v) mixture. After ultrasonic dissolution, 258.4 mg (2 mmol, 1 eq) of (2-aminoethyl)piperazine (AEPZ) was added. After bubbling with argon for 1 minute, the mixture was reacted at 50°C in the dark for 5 days. After the reaction, the reaction solution was removed and allowed to cool to room temperature. 361.7 mg (2.4 mmol, 1.2 eq) of AEPZ was slowly added dropwise and capped at 37°C for 8 hours. After capping, the reaction solution was added dropwise to acetone for precipitation, with 20 drops of the reaction solution added per 20 mL and shaken vigorously to precipitate. After precipitation, the solution was washed three times with acetone and dried under vacuum to obtain a total of 1.1 g of a light yellow foamy solid. The reaction formula is as follows:

[0046]

[0047] Figure 2 is the H NMR spectrum of HPAA in Example 2 of the present invention, such as Figure 2 As shown, HPAA 1 HNMR (600MHz, DMSO-d6): δ8.59-8.53(m, 1H), 8.51(s, 2H), 4.37-4.32(m, 3H), 4.21( s, 1H), 3.15 (s, 1H), 2.63 (ddt, J=36.0, 12.1, 6.6Hz, 5H), 2.50 (s, 2H), 2.45 (dd, J=1 5.1, 7.5Hz, 5H), 2.34 (s, 13H), 2.34 (d, J=17.6Hz, 1H), 2.31-2.24 (m, 3H), 2.20 (dt, J=22.6, 7.1Hz, 7H), 2.09 (s, 2H), 2.03 (s, 0H), 1.86 (d, J=17.7Hz, 1H), 1.76 (s, 1H).

[0048] Example 3: Synthesis of polymer HPDA

[0049] Step S3, Preparation of Polymer HPDA: HPAA (100 mg) was weighed and dissolved in 3 mL of a 7 / 3, v / v, dimethyl sulfoxide / water mixture. DA (50 mg) was added after dissolution. After deoxygenation through argon bubbling, the mixture was reacted at 50°C for 2 days. After completion of the reaction, the reaction solution was concentrated in vacuo and precipitated by adding acetone dropwise, adding 20 drops of the reaction solution per 20 mL and shaking vigorously to precipitate. After precipitation, the mixture was washed three times with acetone and dried in vacuo to obtain 90 mg of a tan powder. The reaction formula is as follows:

[0050]

[0051] Figure 3 The comparison of the H NMR spectrum of HPDA in Example 3 of the present invention with that of DA and HPAA is shown in FIG. Figure 3 As shown in the figure, the appearance of benzene ring proton signals at 6.63 (d, J = 7.9 Hz, 1H), 6.58 (d, J = 2.1 Hz, 1H), and 6.43 (dd, J = 7.9, 2.1 Hz, 1H) in HPDA and the disappearance of double bond proton signals at 6.19 (dd, J = 17.1, 10.2 Hz, 1H), 6.06 (dd, J = 17.1, 2.2 Hz, 1H), and 5.56 (dd, J = 10.2, 2.2 Hz, 1H) in HPDA proved that DA reacted with the amino group at the end of HPAA through Michael addition reaction, thereby successfully synthesizing the conjugate of DA and HPAA HPDA.

[0052] Example 4: Synthesis of polymer PLDA

[0053] Step S4, preparation of polymer PLDA: Weigh polylysine (PLL, 100 mg; polylysine brand: Adamas, product number: 3327319A, CAS: 25104-18-1) and dissolve it in 3 mL of a methanol / water (7 / 3, v / v) mixed solvent. Then add 0.1N sodium hydroxide solution (2 mL) to adjust the pH to 8-9. After adding DA (100 mg), argon gas is bubbled to deoxygenate for 1 minute. The reaction is carried out at 50°C in the dark for 2 days. After the reaction is completed, the reaction solution is taken out and allowed to cool to room temperature, vacuum dried and concentrated to remove methanol. The concentrated reaction solution is dripped dropwise into a mixed solution of acetone / ether (3 / 1, v / v), adding 20 drops per 20 mL and shaking vigorously to precipitate it. After precipitation is completed, the precipitate is redissolved with methanol (0.8 mL) and dripped into acetone for secondary precipitation, finally obtaining 120 mg of a beige powdery solid. The reaction formula is as follows

[0054]

[0055] Wherein, x is the number of repeating units, x=25-35, m is the number of units not grafted with dopamine, n is the number of units grafted with dopamine, m+n=x, n / m=0.42.

[0056] Figure 4 is the hydrogen nuclear magnetic resonance spectrum of PLL in Example 4 of the present invention, such as Figure 4 As shown, PLL 1 H NMR (600MHz, DMSO-d6): δ8.85 (s, 1H), 8.34 (s, 2H), 3.79 (t, J=6.2Hz, 1H), 3.10 (p, J=7.0Hz, 2H), 1.76 (dt, J=13.8, 7.3Hz, 2H), 1.56-1.25 (m, 4H).

[0057] Figure 5 The comparison of the H NMR spectrum of PLDA and DA and PLL in Example 4 of the present invention is shown in FIG. Figure 5 As shown in the figure, the appearance of benzene ring proton signals at 6.63 (d, J = 7.9 Hz, 1H), 6.58 (d, J = 2.1 Hz, 1H), and 6.43 (dd, J = 7.9, 2.1 Hz, 1H) in PLDA and the disappearance of double bond proton signals at 6.19 (dd, J = 17.1, 10.2 Hz, 1H), 6.06 (dd, J = 17.1, 2.2 Hz, 1H), and 5.56 (dd, J = 10.2, 2.2 Hz, 1H) in PLDA proved that DA reacted with the amino group in PLL through Michael addition reaction, thereby successfully synthesizing the conjugate of DA and PLL, PLDA.

[0058] Example 4: Fluorescence Characterization of Various Compounds

[0059] Figure 6 and Figure 7 The fluorescence emission spectra and fluorescence excitation spectra of DA at different concentrations using DMSO as the solvent are shown. The concentrations of DA are 0.5 / 1 / 2 / 5 / 10 / 20 / 40 / 80 mg / mL, respectively. The overall DA fluorescence is weak. Even at high concentrations, the maximum fluorescence intensity is only 15,000, and the emission range is between 400-500 nm. The optimal emission is at 445 nm, which is within the blue light range.

[0060] Figure 8 This is the excitation-emission matrix spectrum of DA, which more intuitively indicates that its excitation and emission ranges are 350-380nm and 420-480nm, respectively, and are not concentration-dependent.

[0061] Figure 9 and Figure 10The fluorescence emission spectra and fluorescence excitation spectra of HPAA at different concentrations using DMSO as the solvent. The concentrations of HPAA are 0.5 / 1 / 2 / 5 / 10 / 20 / 40 / 80 mg / mL, respectively. The fluorescence characteristics of HPAA are mainly manifested in excitation-dependent emission, concentration-dependent emission, and a wide emission range. Under the excitation of different excitation lights, the peak of its emission curve will have a certain red shift, but the fluorescence intensity in the longer wavelength region is extremely low; the optimal excitation wavelength and the optimal emission wavelength will change with the change of concentration. At 0.5 mg / mL, the optimal excitation and emission wavelengths are 350 nm and 412 nm, at 5 mg / mL, the optimal excitation and emission wavelengths are 365 nm and 445 nm, and at 20 mg / mL, the optimal excitation and emission wavelengths are 380 nm and 455 nm. The overall emission range is 400-550 nm, and the optimal emission is around 450 nm, which appears as blue light emission; the maximum fluorescence intensity increases with the increase of concentration, and the maximum intensity is around 18,000 at 0.5 mg / mL, around 30,000 at 10 mg / mL, and around 73,000 at 80 mg / mL.

[0062] Figure 11 The excitation-emission matrix spectra of HPAA at different concentrations more intuitively show that the excitation and emission ranges are between 365-410nm and 425-510nm. The fluorescence center will red-shift with increasing concentration, from 430nm at low concentration to 470nm at high concentration.

[0063] Figure 12 and Figure 13 The fluorescence emission spectra and fluorescence excitation spectra of HPDA at different concentrations using DMSO as solvent. The concentrations of HPDA are 0.5 / 1 / 2 / 5 / 10 / 20 / 40 / 80 mg / mL, respectively. The fluorescence characteristics of HPDA are mainly manifested in excitation-dependent emission, concentration-dependent emission, a wide emission range and more fluorescence centers. Under the excitation of different excitation lights, the peak of its emission curve will continue to redshift, and the fluorescence in the long-wavelength region is also relatively strong at high concentrations; the optimal excitation wavelength and the optimal emission wavelength will change with the change of concentration, and clearly show three fluorescence centers between 400-500nm, 500-600nm and 600-700nm. As the concentration increases, the contribution of the fluorescence center in the long-wavelength region gradually increases, and its luminescence gradually changes from blue light to green light and then to red light, achieving full-color luminescence in the visible light region; the maximum fluorescence intensity of HPDA in the range of 400-500nm and 500-600nm is about 100,000, and the maximum fluorescence intensity in the range of 600-700nm is 20,000, which is an intensity that neither DA nor HPAA can reach.

[0064] Figure 14The excitation-emission matrix spectrum of HPDA at different concentrations more intuitively shows that the fluorescence center changes from 410-470nm to 500-570nm and then to 620-640nm, realizing true full-color luminescence of the polymer.

[0065] Figure 15 and Figure 16 The following are the fluorescence emission and excitation spectra of PLL at different concentrations using DMSO as the solvent. The concentrations of PLL are 0.5, 1, 2, 5, 10, 20, 40, and 80 mg / mL, respectively. The fluorescence characteristics of PLL are primarily characterized by certain excitation-dependent and concentration-dependent emission. Under different excitation light conditions, the peak of its emission curve continuously red-shifts, similar to HPAA, with lower fluorescence intensity in the long-wavelength region. Unlike HPAA, the optimal excitation and emission wavelengths of PLL do not change with concentration, reaching 350 nm and 425 nm, respectively, within the blue light region. The maximum fluorescence intensity increases with increasing concentration, reaching virtually no fluorescence at 0.5 mg / mL, approximately 50,000 at 10 mg / mL, and approximately 28,000 at 80 mg / mL.

[0066] Figure 17 The excitation-emission matrix spectra of PLL at different concentrations more intuitively show that the fluorescence center does not change with concentration and only emits light in the blue light area.

[0067] Figure 18 and Figure 19The fluorescence emission spectra and fluorescence excitation spectra of PLDA at different concentrations using DMSO as the solvent are shown. The concentrations of PLDA are 0.5 / 1 / 2 / 5 / 10 / 20 / 40 / 80 mg / mL, respectively. As can be seen from the figure, the fluorescence characteristics of PLDA are similar to those of HPDA, mainly manifested in excitation-dependent emission, concentration-dependent emission, a wider emission range, and more fluorescence centers. Under the excitation of different excitation lights, the peak of its emission curve will continue to redshift, and there will be strong fluorescence in the long-wavelength region at high concentrations; the optimal excitation wavelength and the optimal emission wavelength will change with the change of concentration, and clearly show three fluorescence centers between 400-500nm, 500-600nm and 600-700nm. As the concentration increases, the contribution of the fluorescence center in the long-wavelength region gradually increases, and its luminescence gradually changes from blue light to green light and then to red light, achieving full-color luminescence in the visible light region. Unlike HPDA, PLDA has extremely strong fluorescence intensity, with a maximum fluorescence intensity of about 250,000 in the range of 400-500nm, about 570,000 in the range of 500-600nm, and about 120,000 in the range of 600-700nm. Compared with PLL and DA, the fluorescence intensity is greatly increased, achieving high-brightness full-color luminescence.

[0068] Figure 20 The excitation-emission matrix spectrum of PLDA at different concentrations more intuitively shows the change of the fluorescence center from 420-470nm to 470-550nm, as well as the new red fluorescence center between 610-650nm, which also realizes the full-color luminescence of the polymer.

[0069] The present invention protects dopamine with an acryloyl group and then couples the dopamine and the polymer through a Michael addition reaction. On the one hand, the protection inhibits the self-polymerization of dopamine and maintains the accuracy of the structure. On the other hand, dopamine is used as the end group of the polymer to adjust the fluorescence properties of the polymer. On the other hand, the polymer is used as a skeleton to support dopamine and prevent π-π stacking between dopamine groups from causing fluorescence quenching. Compared with existing fluorescent polymers and fluorescent dopamine, the present invention truly achieves full-color regulation of unconventional luminescent polymers and a new method for processing fluorescent dopamine, providing a feasible and effective idea for the design of new fluorescent materials.

[0070] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing an unconventional full-color luminescent polymer coupled with dopamine and a polymer, characterized by: The following steps are included: (1) Preparation of DA monomer: dopamine hydrochloride and triethylamine were added to ultra-dry pyridine, and after deoxygenation, acrylic anhydride diluted with ultra-dry tetrahydrofuran was added dropwise, stirred at 0°C, and gradually returned to room temperature after the addition was completed, and stirred overnight; after the reaction was completed, the obtained reaction solution was vacuum dried and concentrated, acetone was added to dissolve the residue, and the insoluble components were removed by filtration. After the filtrate was concentrated to remove the acetone, deionized water and ethyl acetate were added and stirred, and the organic phase was washed, dried over anhydrous sodium sulfate, and purified by column chromatography; (2) Preparation of polymer HPAA: N,N′-methylenebisacrylamide and (2-aminoethyl)piperazine were dissolved in methanol / water solvent, and reacted at 50°C in the dark for 5 days after deoxygenation. After the reaction was completed, (2-aminoethyl)piperazine was slowly added dropwise, and the end-capping reaction was carried out at 37°C for 8 hours. The resulting reaction solution was added dropwise to acetone for precipitation. (3) Preparation of polymer HPDA: Dissolve the HPAA and DA monomers in dimethyl sulfoxide / water solvent, deoxygenate, and react at 50°C for 2 days. After the reaction is completed, vacuum concentrate the reaction solution and add the reaction solution dropwise into acetone for precipitation; or, (4) Preparation of polymer PLDA: Weigh polylysine and DA monomers and dissolve them in methanol / water. Then add sodium hydroxide solution to adjust the pH to 8-9. After deoxygenation, react at 50°C in the dark for 2 days. After the reaction is completed, take out the reaction solution and let it cool to room temperature. Then vacuum dry and concentrate to remove methanol. The concentrated reaction solution is then added dropwise into acetone / ether for precipitation.

2. The method for preparing the unconventional full-color luminescent polymer coupled with dopamine and polymer according to claim 1, characterized in that: In step (1), the molar ratio of dopamine hydrochloride to triethylamine is 1:

2.

3. The method for preparing the unconventional full-color luminescent polymer coupled with dopamine and polymer according to claim 2, characterized in that: In step (1), 36.9 mmol of dopamine hydrochloride is placed in a three-necked flask, 80 mL of ultra-dry pyridine and 73.8 mmol of triethylamine are added, and the mixture is deoxygenated by bubbling with argon for 10 min under slow stirring. 36.9 mmol of acrylic anhydride is diluted with 10 mL of ultra-dry tetrahydrofuran and placed in a dropping funnel, and argon is bubbled for 1 min. The entire reaction system is sealed and placed in an ice bath at 0°C and stirred for 5 min. The dropping funnel is opened and the rate is adjusted to 2 s / drop to allow acrylic anhydride to drip into the three-necked flask. After the addition is completed, the mixture gradually returns to room temperature and is stirred overnight. After the reaction is completed, the reaction solution is vacuum dried and concentrated, 50 mL of acetone is added to dissolve the residue, and the insoluble components are removed by filtration. After the filtrate is concentrated to remove acetone, 50 mL of deionized water and 75 mL of ethyl acetate are added and stirred for 1 h. The aqueous phase is separated and removed, and the organic phase is washed twice with 1 M hydrochloric acid solution and twice with concentrated brine, then dried over anhydrous sodium sulfate and concentrated to obtain a light yellow viscous liquid, which is purified by column chromatography to obtain a white powdery solid.

4. The method for preparing an unconventional full-color luminescent polymer coupled with dopamine and a polymer according to any one of claims 1 to 3, characterized in that: In step (2), 616.68 mg of N,N′-methylenebisacrylamide was weighed and dissolved in 8 mL of methanol / water mixed solution. After ultrasonic dissolution, 258.4 mg of (2-aminoethyl)piperazine was added, and argon bubbling was used to deoxygenate for 1 min, and then the reaction was carried out at 50 °C in the dark for 5 days. After the reaction was completed, the reaction solution was taken out and cooled to room temperature, and 361.7 mg of (2-aminoethyl)piperazine was slowly added dropwise, and the end-capping was carried out at 37 °C for 8 h. After the end-capping was completed, the reaction solution was added dropwise to acetone for precipitation. After the precipitation was completed, it was washed with acetone three times and vacuum dried to obtain a light yellow foamy solid.

5. The method for preparing the unconventional full-color luminescent polymer coupled with dopamine and polymer according to claim 4, characterized in that: In step (2), the volume ratio of methanol to water in the methanol / water mixed solution is 7:

3.

6. The method for preparing an unconventional full-color luminescent polymer coupled with dopamine and a polymer according to any one of claims 1 to 3, characterized in that: In step (3), 100 mg of HPAA was weighed and dissolved in 3 mL of a dimethyl sulfoxide / water mixed solvent. After dissolution, 50 mg of DA was added, and the mixture was deoxygenated by bubbling with argon and reacted at 50°C for 2 days. After the reaction was completed, the reaction solution was concentrated in vacuo and added dropwise to acetone for precipitation. After precipitation, the mixture was washed with acetone and dried in vacuo to obtain a brown powder.

7. The method for preparing the unconventional full-color luminescent polymer coupled with dopamine and polymer according to claim 6, characterized in that: In step (3), the volume ratio of dimethyl sulfoxide to water in the dimethyl sulfoxide / water mixed solvent is 7:

3.

8. The method for preparing an unconventional full-color luminescent polymer coupled with dopamine and a polymer according to any one of claims 1 to 3, characterized in that: In step (4), 100 mg of polylysine was weighed and dissolved in 3 mL of a methanol / water mixed solvent with a volume ratio of 7:3, and then 2 mL of sodium hydroxide solution was added, the pH was adjusted to 8-9, and 100 mg of DA monomer was added and argon was bubbled for deoxygenation for 1 min. The reaction was carried out at 50°C in the dark for 2 days. After the reaction was completed, the reaction solution was taken out and allowed to cool to room temperature, vacuum dried and concentrated to remove methanol, and the concentrated reaction solution was dripped dropwise into an acetone / ether mixed solution with a volume ratio of 3:1 to precipitate. After the precipitation was completed, the precipitate was redissolved with 0.8 mL of methanol and dripped into acetone for secondary precipitation, finally obtaining a beige powdery solid.

9. The product obtained by the method for preparing the unconventional full-color luminescent polymer coupled with dopamine and polymer according to claim 1.

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