CN114716659A - Method for preparing nitrogen-containing polymer through click polymerization without catalyst - Google Patents

Abstract

The invention relates to a method for preparing nitrogen-containing polymer by click polymerization without catalyst, and belongs to the field of fluorescent polymer synthesis. In the present invention, the tertiary amine-containing diol or polyol is used as the hydroxyl monomer, and the activated alkynyl monomer can be prepared under catalyst-free conditions to obtain linear and hyperbranched nitrogen-containing products with high yield, regular structure and high molecular weight. polymer. The polymerization method of the invention does not need to add a catalyst, is environmentally friendly, has the advantages of mild reaction conditions, high reaction efficiency and high yield, is suitable for large-scale production applications, and has huge application prospects. And the obtained polymer has the characteristics of regular structure, controllable, modifiable and stable autofluorescence properties, and is suitable for application in different fields.

Description

A method for preparing nitrogen-containing polymer by click polymerization without catalyst

technical field

The invention belongs to the field of fluorescent polymer synthesis, and in particular relates to a method for preparing nitrogen-containing polymer by click polymerization reaction without catalyst.

Background technique

Nitrogen-containing polymers not only exist widely in life, but also play an important role in our production and life as one of the important types of synthetic polymers. In addition, the researchers found that the nitrogen-containing polymers also exhibited remarkable photoluminescence properties in the aggregated state, which belonged to non-traditional fluorescent polymer materials. Compared with traditional polymer photoluminescent materials, non-traditional fluorescent polymers have the advantages of easy preparation, good hydrophilicity and good biocompatibility, and they have become ideal candidates for sensor, biological and medical applications. Therefore, the development of new methods to synthesize nitrogen-containing polymers is of great significance for enriching the types of fluorescent polymers and understanding the fluorescence mechanism.

Click polymerization is developed from the click reaction. It has the advantages of good selectivity, wide application range, mild conditions, high efficiency, no by-products, and atom economy. It is an efficient method for synthesizing nitrogen-containing polymers. At present, researchers have realized that high-yield nitrogen-containing polymerization can be prepared by click polymerization with nucleophilic amine monomer and unsaturated bond monomer (double bond or triple bond) at room temperature and without catalysis. thing. Hydroxyl monomers, like amino monomers, are also a class of commonly used nucleophiles. Compared with amines, alcohol monomers have the advantages of many types, wide sources, good stability, and non-toxic and non-irritating odor. However, since the nucleophilicity of alcohols is not as strong as that of the former, the current hydroxy-alkyne-based click polymerization usually shows the disadvantages of poor activity, reversible reaction, and uncontrollable stereoselectivity. Although there are few methods for preparing nitrogen-containing polymers based on the click polymerization of hydroxyl and unsaturated bond monomers, all current polymerization systems require additional catalysts. Therefore, the development of a catalyst-free hydroxy-alkyne click polymerization to prepare nitrogen-containing polymers with high molecular weight and controllable structure is a very meaningful subject.

SUMMARY OF THE INVENTION

Based on the disadvantage that all current click polymerization reactions of hydroxyl and alkynes require additional catalysts, the present invention provides a click polymerization reaction of hydroxyl and alkynes without adding catalysts to prepare nitrogen-containing polymerizations with different topological structures (linear or branched). method of things. The polymerization does not require additional catalyst, and has the advantages of mild reaction conditions, high reaction yield, regular polymer structure, etc., and the polymer has intrinsic luminescence properties, which is an economical, green and environmentally friendly method for preparing fluorescent polymers with different topological structures. .

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for preparing polymers by click polymerization without catalyst, based on the polymerization of hydroxyl and alkynyl monomers, which is prepared by tertiary amine-containing alcohol and activated alkyne monomers under mild conditions to obtain regular structure and higher molecular weight Linear or branched nitrogen-containing polymers.

Further, the tertiary amine-containing alcoholic hydroxyl monomer is an aliphatic tertiary amine-containing diol or triol monomer or a cyclic tertiary amine-containing diol or triol monomer. On the other hand, the aromatic tertiary amine-containing monomer cannot react spontaneously under the conditions of the present invention. Spontaneous reaction can only be guaranteed under the condition of having specific tertiary amine hydroxyl monomer and activated alkyne monomer at the same time.

n为1～5；R为甲基，丁基或脂环基团；The structure of diols containing tertiary amines is:

n is 1-5; R is methyl, butyl or alicyclic group;

R1为氢或甲基；The structure of triols containing tertiary amines is

R1 is hydrogen or methyl;

Cyclic tertiary amine-containing diol structures are:

For example, tertiary amine-containing alcohol hydroxyl monomers include N-methyldiethanolamine, N,N-bis(2-hydroxyethyl)piperazine or triethanolamine.

Further, the activated alkyne monomer is a difunctional activated terminal alkyne monomer or a multifunctional activated terminal alkyne monomer.

Among them, the structural formula of the bifunctional activated terminal alkyne monomer is:

n is 1-4, and m is 1-3.

The structural formula of the multifunctional ester-activated terminal alkyne monomer is:

Further, activated terminal alkyne monomers include 1,6-hexanediol dipropynoate, 1,4-butanediol dipropynoate, ethylene glycol dipropynoate, and the like.

The molar ratio of the tertiary amine-containing alcoholic hydroxyl monomer to the activated alkyne monomer can be any ratio. As a preference: when the bifunctional monomer is polymerized to obtain a linear polymer, the molar ratio of the hydroxyl group and the alkynyl group in the monomer is 1:1, which is beneficial to obtain a polymer with a larger molecular weight.

Further, the reaction scheme of some linear nitrogen-containing polymers is as follows:

wherein R is methyl, butyl, _alicyclic hydrocarbon or _CH2CH2OH .

Further, the reaction scheme of the partially branched nitrogen-containing polymer is as follows:

Further, the mild polymerization conditions are a wide range of polymer temperature: -25 to 60 °C, the polymerization environment is unlimited, and the polymerization can be carried out spontaneously under nitrogen or air and with or without solvent, and the reaction time is within 24h. After the reaction, a high yield of more than 80% is obtained; the nitrogen-containing polymer containing more than 97% of the E configuration is obtained.

Further, the nitrogen-containing polymers synthesized in the present invention have intrinsic fluorescence properties, and exhibit concentration-enhanced fluorescence and excitation wavelength-dependent fluorescence properties. Furthermore, nitrogen-containing polymers can be imaged in cells and are a potential biomedical fluorescent material.

Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention uses a tertiary amine-containing diol or polyol as a hydroxyl monomer, and is prepared with an activated alkynyl monomer under catalyst-free conditions to obtain high yield, Linear and hyperbranched nitrogen-containing polymers with regular structure and high molecular weight. The polymerization method of the invention does not need to add a catalyst, is environmentally friendly, has the advantages of mild reaction conditions, high reaction efficiency and high yield, is suitable for large-scale production applications, and has huge application prospects. And the obtained polymer has the characteristics of regular structure, controllable, modifiable and stable autofluorescence properties, and has broad application prospects in the fields of sensors, biology and medicine.

Description of drawings

Fig. 1 Hydrogen nuclear magnetic spectrum of the polymer obtained in Example 1 and the corresponding monomer.

Fig. 2 Hydrogen nuclear magnetic spectra of the polymers obtained in Examples 2, 3 and 4.

Figure 3 shows the fluorescence spectra of the polymers and corresponding monomers obtained in Examples 1, 2, 3 and 4.

Fig. 4 Fluorescence spectra of the polymer obtained in Example 1 under (A) different concentrations and (B) different excitation wavelengths.

Fig. 5 (A) the hydrogen nuclear magnetic spectrum of the polymer obtained in Example 6 and the fluorescence spectrum at (B) different concentrations and (C) different excitation wavelengths.

FIG. 6 (A) the hydrogen NMR spectrum of the polymer obtained in Example 7 and the fluorescence spectrum at (B) different concentrations and (C) different excitation wavelengths.

Fig. 7 (A) the hydrogen NMR spectrum of the polymer obtained in Example 8 and the fluorescence spectrum at (B) different concentrations and (C) different excitation wavelengths.

Fig. 8 (A) the hydrogen NMR spectrum of the polymer obtained in Example 9 and the fluorescence spectrum at (B) different concentrations and (C) different excitation wavelengths.

Fig. 9 (A) the hydrogen NMR spectrum of the polymer obtained in Example 11 and the fluorescence spectrum at (B) different concentrations and (C) different excitation wavelengths.

Fig. 10 Intracellular imaging diagram of the polymer obtained in Example 1.

Detailed ways

The method for preparing polymers based on the catalyst-free hydroxy-alkyne click polymerization described in the present invention is as follows: wherein all the monomers are commercially available or easily synthesized.

可参考公开文献(Polymer Chemistry,2020,11(14):2568-2575.)的合成方法合成。For example where the activated ester alkyne monomer

It can be synthesized by referring to the synthetic method of the published literature (Polymer Chemistry, 2020, 11(14): 2568-2575.).

Example 1:

N-methyldiethanolamine (0.119g, 1equiv) and 1,6-hexanediol dipropiolate (0.222g, 1equiv) were added to a 5mL single-neck polymerization bottle, and placed at 25°C under argon protection The reaction was stirred for 24h. After the reaction, the mixture was precipitated with n-hexane to obtain a polymer (LP-1) with 97% yield and 100% E configuration, and the structure of the target polymer was confirmed by NMR spectroscopy (Fig. 1). The weight average molecular weight of the polymer was 21000 g/mol and the molecular weight distribution was 2.28 by size exclusion chromatography. The fluorescence properties of the polymers were characterized using a fluorescence spectrometer (Fig. 3), showing concentration-dependent enhancement and excitation wavelength-dependent fluorescence properties (Fig. 4). It is indicated that this method can realize the spontaneous polymerization to prepare linear fluorescent polymers with higher molecular weight and regular structure. Cell experiments show that the fluorescent polymer can be imaged in cells (Fig. 10), which is a potential biomedical fluorescent material.

Example 2:

N-methyldiethanolamine 0.119g, 1equiv) and 1,6-hexanediol dipropiolate (0.222g, 1equiv) were added to a 5mL single-neck polymerization bottle, and the reaction was stirred at -25°C in the air for 24h . After the reaction was completed, the mixture was precipitated with n-hexane to obtain a polymer (LP-2) with 90% yield and 98% E configuration. The structure of the target polymer was confirmed by NMR spectroscopy (Figure 2). The weight-average molecular weight of the polymer was 9600 g/mol and the molecular weight distribution was 1.94 by size exclusion chromatography. The fluorescence properties of the polymer were characterized by fluorescence spectrometer (Fig. 3). It is indicated that this method can realize the spontaneous polymerization to prepare linear fluorescent polymers with higher molecular weight and regular structure.

Example 3:

N-methyldiethanolamine (0.119g, 1equiv) and 1,6-hexanediol dipropiolate (0.222g, 1equiv) were added to a 5mL single-neck polymerization flask and stirred for reaction, and stirred at 25°C in the air Reaction for 24h. After the reaction was completed, the mixture was precipitated with n-hexane to obtain a polymer (LP-3) with 96% yield and 100% E configuration, and the structure of the target polymer was confirmed by NMR (Figure 2). The weight-average molecular weight of the polymer was 26800 g/mol and the molecular weight distribution was 2.35 by size exclusion chromatography. The fluorescence properties of the polymer were characterized by fluorescence spectrometer (Fig. 3). It is indicated that this method can realize the spontaneous polymerization to prepare linear fluorescent polymers with higher molecular weight and regular structure.

Example 4:

N-methyldiethanolamine (0.119g, 1equiv) and 1,6-hexanediol dipropiolate (0.222g, 1equiv) were added to a 5mL single-neck polymerization bottle, and the reaction was stirred at 60°C in the air for 24h . After the reaction was completed, the mixture was precipitated with n-hexane to obtain a polymer with a yield of 99%. The polymer was characterized by size exclusion chromatography with a weight average molecular weight of 71700 g/mol and a molecular weight distribution of 2.75. It was confirmed by proton NMR that the click polymerization of hydroxy-alkyne without catalyst could proceed spontaneously (Fig. 2), and 100% Linear polymer in E configuration (LP-4). The fluorescence properties of the polymers were characterized using a fluorescence spectrometer (Figure 3). It is indicated that this method can realize the spontaneous polymerization to prepare linear fluorescent polymers with higher molecular weight and regular structure.

Example 5:

N-butyldiethanolamine (0.119g, 1equiv) and 1,6-hexanediol dipropiolate (0.222g, 1equiv) were added to a 5mL single-neck polymerization bottle, and the reaction was stirred at 25°C in the air for 24h . After the reaction was completed, the mixture was precipitated with n-hexane to obtain a polymer with a yield of 96%. The weight-average molecular weight of the polymer was 14600 g/mol and the molecular weight distribution was 2.33 by size exclusion chromatography. It is indicated that this method can realize spontaneous polymerization to prepare nitrogen-containing linear polymers of higher molecular weight.

Example 6:

N-methyldiethanolamine (0.119 g, 1 equiv) and 1,4-butanediol dipropiolate (0.194, 1 equiv) were added to a 5 mL single-neck polymerization flask, and the reaction was stirred at 25° C. in air for 24 h. After the reaction was completed, the mixture was precipitated with n-hexane to obtain a polymer with a yield of 85%. The weight-average molecular weight of the polymer was 20400 g/mol and the molecular weight distribution was 1.96 by size exclusion chromatography. It was confirmed by proton NMR that the click polymerization of hydroxy-alkyne without catalyst could proceed spontaneously, and a 100% E configuration was obtained. Linear polymer (LP-5). The fluorescence properties of the polymers were characterized using a fluorescence spectrometer and exhibited concentration-dependent enhancement and excitation wavelength-dependent fluorescence properties (Figure 5). It is indicated that this method can realize the spontaneous polymerization to prepare linear fluorescent polymers with higher molecular weight and regular structure.

Example 7:

N-methyldiethanolamine (0.119 g, 1 equiv) and ethylene glycol dipropioate (0.166 g, 1 equiv) were added to a 5 mL single-neck polymerization bottle, and the reaction was stirred at 45 degrees in air for 24 h. After the reaction was completed, the mixture was precipitated with n-hexane to obtain a polymer with a yield of 80%. The weight-average molecular weight of the polymer was 18700 g/mol and the molecular weight distribution was 1.75 by size exclusion chromatography. It was confirmed by proton nuclear magnetic resonance spectroscopy that the click polymerization of hydroxy-alkyne without catalyst could proceed spontaneously, and a 100% E configuration was obtained. Linear polymer (LP-6). The fluorescence properties of the polymers were characterized using a fluorescence spectrometer and exhibited concentration-dependent enhancement and excitation wavelength-dependent fluorescence properties (Figure 6). It is indicated that this method can realize the spontaneous polymerization to prepare linear fluorescent polymers with higher molecular weight and regular structure.

Example 8:

Add N,N-bis(2-hydroxyethyl)piperazine (0.174g, 1equiv) and 1,6-hexanediol dipropiolate (0.222g, 1equiv) to a 10mL single-neck polymerization bottle, add water / dimethyl sulfoxide mixed solvent (0.5 mL volume ratio is 1:4), and the reaction was stirred at 60° C. for 24 h in the air. After the reaction, the polymer was precipitated with n-hexane to obtain a linear polymer with 82% yield and 97% E configuration. The polymer was characterized by size exclusion chromatography with a weight average molecular weight of 11585 g/mol and a molecular weight distribution of 1.50. The fluorescence properties of the polymers were characterized by fluorescence spectrometer and exhibited concentration-dependent enhancement and excitation wavelength-dependent fluorescence properties (Fig. 7). It is indicated that this method can realize spontaneous polymerization to prepare linear polymers with higher molecular weight and regular structure.

Example 9:

Triethanolamine (0.1492g, 1equiv), ethylene glycol dipropiolate (0.1660g, 1equiv) and N,N-dimethylformamide (0.3mL) were added to a 10mL single-neck polymerization bottle, and in an air environment The reaction was stirred at 25°C for 24h. After the reaction, the polymer was precipitated with ether to obtain a branched polymer with a yield of 84% and an E configuration of 98%. The structure of the target polymer was confirmed by NMR spectroscopy, and the branching degree of the polymer was calculated to be 0.72. The weight-average molecular weight of the polymer was 48000 g/mol and the molecular weight distribution was 2.68 by size exclusion chromatography. The fluorescence properties of the polymers were characterized by fluorescence spectrometer and exhibited concentration-dependent enhancement and excitation wavelength-dependent fluorescence properties (Fig. 8). It is indicated that this method can realize spontaneous polymerization to prepare branched fluorescent polymers with higher molecular weight and regular structure.

Example 10:

Triethanolamine (0.1492g, 1equiv), ethylene glycol dipropiolate (0.249g, 1.5equiv) and dichloromethane (0.3mL) were added to a 10mL single-neck polymerization bottle, and placed at 25°C in an air environment The reaction was stirred for 12h. After the reaction was completed, the polymer was precipitated with ether to obtain a branched polymer with a yield of 88% and an E configuration of 99%. The branching degree of the polymer was calculated by hydrogen nuclear magnetic resonance spectroscopy to be 0.69, and the polymer was characterized by size exclusion chromatography. The weight-average molecular weight was 69200 g/mol, and the molecular weight distribution was 3.04, indicating that this method can prepare branched polymers with higher molecular weight and regular structure.

Example 11:

Triethanolamine (0.1492g, 1equiv), 1,6-hexanediol dipropynoate (0.222g, 1equiv) and dimethylformamide (0.5mL) were added to a 10mL single-neck polymerization bottle, respectively, in an air environment The reaction was stirred at 25°C for 12h. After the reaction is completed, the polymer is precipitated with ether to obtain a branched polymer with a yield of 90% and an E configuration of 99%. The branching degree of the polymer is calculated by hydrogen nuclear magnetic resonance spectrum to be 0.70, and the polymer is characterized by size exclusion chromatography. The weight-average molecular weight of the polymer was 62500 g/mol, and the molecular weight distribution was 2.95. The fluorescence properties of the polymer were characterized by a fluorescence spectrometer, and showed concentration-dependent enhancement and excitation wavelength-dependent fluorescence characteristics (Figure 9). It is indicated that this method can realize spontaneous polymerization to prepare branched fluorescent polymers with higher molecular weight and regular structure.

Example 12:

Triisopropanolamine (0.1912g, 1equiv), ethylene glycol dipropiolate (0.1660g, 1equiv) and dichloromethane (0.3mL) were added to a 10mL single-neck polymerization bottle, and placed in an air environment. The reaction was stirred at 25°C for 12h. After the reaction was completed, the polymer was precipitated with ether to obtain a nitrogen-containing branched polymer with a yield of 81%. The weight-average molecular weight of the polymer was 20200 g/mol and the molecular weight distribution was 2.94 by size exclusion chromatography, indicating that this method can be prepared. Higher molecular weight nitrogen-containing branched polymers are obtained.

Claims (5)

1. A method for preparing a nitrogen-containing polymer by click polymerization without a catalyst is characterized by comprising the following steps: and (2) carrying out click polymerization reaction on the tertiary amine-containing alcoholic hydroxyl monomer and activated ester alkyne monomer or activated ketone alkyne monomer under the condition of no catalyst to prepare the linear or branched nitrogen-containing polymer with regular structure.

2. The method for preparing nitrogen-containing polymer by click polymerization without catalyst according to claim 1, wherein the tertiary amine-containing alcoholic hydroxyl monomer is aliphatic tertiary amine structure-containing diol or triol monomer or cyclic tertiary amine-containing diol or triol monomer.

3. The method for preparing a nitrogen-containing polymer by the catalyst-free click polymerization according to claim 1, wherein the reaction temperature in the polymerization reaction condition is in the range of-25 to 60 ℃; the reaction time is within 24 h.

4. The method for preparing a nitrogen-containing polymer by the catalyst-free click polymerization according to claim 1, wherein the polymerization reaction conditions are nitrogen or air; spontaneous reaction with or without solvent.

5. Use of a nitrogen-containing polymer prepared according to any one of claims 1 to 4 as a fluorescent material.

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