An alkylpyridinium salt type aggregation-induced emission compound, and a preparation method and application thereof

Abstract

The application discloses an alkyl pyridine salt type aggregation-induced emission compound, a preparation method and application thereof, a molecular structural formula of the alkyl pyridine salt type aggregation-induced emission compound is as follows: the preparation method comprises the following steps: stirring and refluxing raw material D, 1,4-dimethyl pyridine-1-iodide, anhydrous ethanol and piperidine overnight, after the reaction mixture is cooled, vacuum concentration is carried out, and the crude product is purified by elution, so that the alkyl pyridine salt type aggregation-induced emission compound is obtained. The alkyl pyridine salt type aggregation-induced emission compound provided by the application can simultaneously and efficiently kill gram-positive bacteria and gram-negative bacteria.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of multifunctional organic small molecule synthesis, and particularly relates to an alkyl pyridine salt type aggregation-induced emission compound, a preparation method and application thereof. BACKGROUND

[0002] Bacterial infectious diseases pose a great threat to human health. The use of broad-spectrum antibiotics leads to the development and spread of bacterial drug resistance, which seriously hinders the fight against bacterial infections. Photodynamic therapy (PDT) is considered a potential means to eliminate pathogenic bacteria, because it is less likely to lead to drug resistance. Compared with antibiotics with specific action targets, the generated reactive oxygen species (ROS) under light irradiation further damages the internal or external structure of bacteria, making it difficult for bacteria to develop resistance to PDT, and the photosensitizer does not need to penetrate the bacterial cell membrane and enter the interior of the bacteria, thus having a different bactericidal mechanism from traditional antibiotics. At the same time, photodynamic antibiosis is based on the synergistic action of the oxidation damage mechanism of the three factors of light, photosensitizer and oxygen, so it will not produce resistance problems due to factors such as single drug use, insufficient photosensitizer concentration, and exposure time.

[0003] Most of the current photosensitizers (PSs) exhibit obvious antibacterial effect on gram-positive bacteria, and there is a lack of photosensitizers for killing gram-negative bacteria, which may be due to the fact that the outer layer of gram-negative bacteria is mainly composed of a thin peptidoglycan layer (-8 nm) and an outer membrane strain composed of lipids and lipopolysaccharides, making it difficult for photosensitizers to bind to gram-negative bacteria, and the antibacterial effect is not satisfactory. SUMMARY

[0004] The present application aims to provide an alkyl pyridine salt type aggregation-induced emission compound, a preparation method and application thereof, which can kill gram-positive bacteria and gram-negative bacteria through photodynamic action.

[0005] In one aspect of the present application, an alkyl pyridine salt type aggregation-induced emission compound is provided. According to an embodiment of the present application, the molecular structure of the alkyl pyridine salt type aggregation-induced emission compound is as follows:

[0006]

[0007] In addition, the alkyl pyridine salt type aggregation-induced emission compound according to the above-mentioned embodiment of the present application can also have the following additional technical features:

[0008] In some embodiments of the present application, the alkyl pyridine salt type aggregation-induced emission compound has near-infrared fluorescence emission.

[0009] In another aspect of the present application, the present application provides a preparation method of an alkyl pyridine salt type aggregation-induced emission compound. According to an embodiment of the present application, the method comprises the following steps: stirring raw material D and 1,4-dimethylpyridine-1-iodide, anhydrous ethanol, and piperidine under reflux overnight, after the reaction mixture is cooled, it is concentrated under reduced pressure, and the crude product is purified by elution to obtain the alkyl pyridine salt type aggregation-induced emission compound.

[0010] wherein, the structural formula of the raw material D is as follows:

[0011]

[0012] In addition, the preparation method of an alkyl pyridine salt type aggregation-induced emission compound according to the above-mentioned embodiment of the present application can also have the following additional technical features:

[0013] In some embodiments of the present application, the molar ratio of the raw material D and 1,4-dimethylpyridine-1-iodide is 1:1-1:2.

[0014] In some embodiments of the present application, the preparation method of the raw material D comprises the following steps: mixing raw material C, 1-bromododecane, KI, and K2CO3 with acetonitrile under nitrogen, stirring under reflux overnight, after cooling to room temperature, extracting the reaction mixture with water and dichloromethane, then drying and concentrating, and purifying the crude product by silica gel elution chromatography with a mixture of petroleum ether and ethyl acetate to obtain the raw material D.

[0015] wherein, the structural formula of the raw material C is as follows:

[0016]

[0017] In some embodiments of the present application, the preparation method of the raw material C comprises the following steps: adding raw material B, 4-formylphenylboronic acid, Pd(dppf)Cl2, and K2CO3 into anhydrous toluene / methanol solution under nitrogen, stirring at 90-110°C overnight, after cooling to room temperature, extracting the solution with water and dichloromethane, drying and concentrating, and purifying the crude product by silica gel elution chromatography with a mixture of petroleum ether and dichloromethane to obtain the raw material C.

[0018] wherein, the structural formula of the raw material B is as follows:

[0019]

[0020] In some embodiments of the present application, the preparation method of the raw material B comprises the following steps: dissolving A in chloroform under ice bath conditions, adding a mixed solution of dichloromethane and boron tribromide dropwise into the above mixture, then reacting at room temperature for 16-18 hours, adding methanol dropwise to quench the excess boron tribromide, after cooling to room temperature, extracting the reaction mixture with ethyl acetate, washing the organic layer with saturated sodium bicarbonate and water, drying and concentrating, purifying the crude product by column chromatography with a mixed solution of petroleum ether and ethyl acetate to obtain the raw material B;

[0021] The structural formula of the raw material A is as follows:

[0022]

[0023] In another aspect of the present application, the present application provides an application of an alkyl pyridine salt type aggregation-induced emission compound. According to an embodiment of the present application, the alkyl pyridine salt type aggregation-induced emission compound is used to produce reactive oxygen and singlet oxygen under light conditions.

[0024] In addition, the application of an alkyl pyridine salt type aggregation-induced emission compound according to the above-mentioned embodiments of the present application can also have the following additional technical features:

[0025] In some embodiments of the present application, the alkyl pyridine salt type aggregation-induced emission compound is used to prepare a fluorescent probe photosensitizer for photodynamic therapy.

[0026] In another aspect of the present application, the present application provides an application of an alkyl pyridine salt type aggregation-induced emission compound. According to an embodiment of the present application, the alkyl pyridine salt type aggregation-induced emission compound kills gram-positive bacteria and gram-negative bacteria through photodynamic action.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] (1) The alkyl pyridine salt type aggregation-induced emission compound has strong push-pull electron effect and large stokes shift, so that the absorption and emission wavelength of the molecule is relatively red, and it has near-infrared fluorescence emission. The push-pull electron structure can promote intersystem crossing, so that energy can more easily reach the triplet state, and the oxygen around the fluorescent probe photosensitizer is converted into reactive oxygen. The reactive oxygen will cause the death of bacteria, thereby realizing photodynamic killing.

[0029] (2) The pyridine salt in the molecular structure of the alkyl pyridine salt type aggregation-induced emission compound carries a positive charge, the bacterial surface has a negative charge, due to the electrostatic interaction between the positive and negative charges, the positive aggregation-induced emission molecules are easy to aggregate on the bacterial surface, which provides a prerequisite for killing gram bacteria; since the cell membrane of bacteria is composed of phospholipid bilayer, a suitable lipid-water partition coefficient and a simulated phospholipid spatial structure enable the aggregation-induced emission molecules to adhere to the cell membrane of bacteria; the aggregation-induced emission molecules in the present application are easy to insert into the cell membrane of gram bacteria when co-cultured with bacteria, so that they can effectively act on gram bacteria. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The nuclear magnetic resonance hydrogen spectrum of compound B in the embodiment 1 of the present application is shown in the following figure;

[0031] Figure 2 The nuclear magnetic resonance hydrogen spectrum of compound C in the embodiment 1 of the present application is shown in the following figure;

[0032] Figure 3 The nuclear magnetic resonance hydrogen spectrum of compound D in the embodiment 1 of the present application is shown in the following figure;

[0033] Figure 4 The nuclear magnetic resonance hydrogen spectrum of compound C12 in the embodiment 1 of the present application is shown in the following figure;

[0034] Figure 5 The nuclear magnetic resonance carbon spectrum of compound C12 in the embodiment 1 of the present application is shown in the following figure;

[0035] Figure 6 The high resolution mass spectrum of compound C12 in the embodiment 1 of the present application is shown in the following figure;

[0036] Figure 7 The absorption spectrum of compound C12 in the embodiment 3 of the present application is shown in the following figure;

[0037] Figure 8 The aggregation-induced emission (AIE) spectrum of compound C12 in the embodiment 4 of the present application is shown in the following figure, in which, the curves from top to bottom are 99%-0, and 0, 10%, 20%, 30%…99% represent the volume content of toluene in dimethyl sulfoxide / toluene mixed solution;

[0038] Figure 9 The AIE dot plot of compound C12 in the embodiment 4 of the present application is shown in the following figure;

[0039] Figure 10 The ROS production ability of compound C12 in the embodiment 5 of the present application under light irradiation is shown in the following figure;

[0040] Figure 11 The ROS production ability of compound C12 in the embodiment 5 of the present application under light irradiation is shown in the following figure; 1O2 production capacity graph;

[0041] Figure 12 Figure 6 is a photograph of agar plates of P. syringae, P. aeruginosa, and S. aureus treated with / without C12 and in dark / light conditions for Example 6 of the present application;

[0042] Figure 13 Figure 7 is a graph of the number of colonies of P. syringae, P. aeruginosa, and S. aureus treated with / without C12 and in dark / light conditions for Example 6 of the present application;

[0043] Figure 14 Figure 8 is a graph of the number of colonies of P. syringae, P. aeruginosa, and S. aureus treated with / without C12 and in dark / light conditions for Example 6 of the present application; DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0045] Example 1

[0046] A method for preparing an alkylpyridinium salt type aggregation-induced emission compound, comprising the following steps:

[0047] (1) Synthesis of compound B

[0048] Compound A (2.36 g, 6.16 mmol) was dissolved in chloroform (20 mL) and the mixture was cooled to 0°C under ice bath conditions. A solution containing dichloromethane (40 mL) and boron tribromide (24 mL, 24.64 mmol) was added dropwise to the above mixture. Then, the reaction was carried out at room temperature for 16 hours. 10 mL of methanol was added dropwise to quench the excess boron tribromide. After cooling to room temperature, the reaction mixture was extracted with ethyl acetate, the organic layer was washed with saturated sodium bicarbonate and water, dried with anhydrous Na2SO4, and concentrated. The crude product was purified by column chromatography, eluted with petroleum ether / ethyl acetate (4:1, v:v), to obtain the off-white solid product B (1.64 g, yield: 75%).

[0049] The chemical structure of compound B was characterized as shown in Figure 1 , to obtain the characterization data: 1H NMR (600 MHz, DMSO-d6) δ 9.38 (s, 2H), 7.22 (d, J = 8.9 Hz, 2H), 6.91 (d, J = 8.7 Hz, 4H), 6.71 (d, J = 8.7 Hz, 4H), 6.55 (d, J = 8.9 Hz, 2H).

[0050] The synthesis reaction of compound B is as follows:

[0051]

[0052] (2) Synthesis of compound C

[0053] Compound B (1.88 g, 5.20 mmol), 4-formylphenylboronic acid (1.95 g, 13.01 mmol), Pd(dppf)Cl2(0.38 g, 0.52 mmol) and K2CO3(3.60 g, 26.02 mmol) were added to a solution of anhydrous toluene / methanol (1:1, v:v) (100 mL) under nitrogen. The mixture was heated to 100 °C and stirred overnight. After cooling to room temperature, water (50 mL) was added and the solution was extracted with dichloromethane. It was dried over anhydrous Na2SO4and the solvent was removed under reduced pressure. Subsequently, the residue was purified by column chromatography on silica gel using petroleum ether / dichloromethane (10:3, v:v) as eluent to obtain C as a brownish yellow flocculent solid (1.30 g, yield: 66%).

[0054] Compound C was characterized by its chemical structure as shown in Figure 2 and the characterization data obtained were: 1 H NMR (600 MHz, DMSO-d6) δ 9.38 (s, 2H), 7.22 (d, J = 8.9 Hz, 2H), 6.91 (d, J = 8.7 Hz, 4H), 6.71 (d, J = 8.7 Hz, 4H), 6.55 (d, J = 8.9 Hz, 2H).

[0055] The synthesis reaction of compound C is as follows:

[0056]

[0057] (3) Synthesis of compound D

[0058] Compound C (0.10 g, 0.26 mmol), 1-bromododecane (0.33 g, 1.31 mmol), KI (0.03 g, 0.18 mmol) and K2CO3(0.18 g, 1.35 mmol) were dissolved in acetonitrile (20 mL) under N2atmosphere. The reaction mixture was stirred and refluxed overnight. After cooling to room temperature, water was added and the mixture was extracted with dichloromethane three times. The extract was dried over anhydrous Na2SO4and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether / ethyl acetate (10:1, v:v) as eluent to obtain compound D (0.11 g, yield: 60%) as a yellow oil.

[0059] The chemical structure of compound D was characterized as shown in Figure 3 , to obtain characterization data: 1 H NMR (600 MHz, CDC13) δ 10.00 (s, 1H), 7.89 (d, J = 8.1 Hz, 2H), 7.70 (d, J = 7.9 Hz, 2H), 7.46 (d, J = 8.5 Hz, 2H), 7.10 (d, J = 8.6 Hz, 4H), 7.00 (d, J = 8.6 Hz, 2H), 6.86 (d, J = 8.8 Hz, 4H), 3.95 (t, J = 6.5 Hz, 4H), 1.80 (p, J = 6.8 Hz, 4H), 1.47 (q, J = 10.7, 9.1 Hz, 4H), 1.31 (d, J = 10.7 Hz, 32H), 0.91 (t, J = 6.9 Hz, 6H).

[0060] The synthetic reaction formula of compound D is as follows:

[0061]

[0062] (4) Synthesis of compound C12

[0063] D (0.72 g, 1.00 mmol), 1,4-dimethylpyridine-1-iodide (0.23 g, 1.00 mmol) and a few drops of piperidine were added to dry ethanol (15 mL) under N2atmosphere. The reaction mixture was refluxed overnight. After cooling to room temperature, the solvent was removed under reduced pressure and the crude product was purified by a neutral alumina column using a dichloromethane / methanol (95:5, v:v) mixture as eluent to obtain compound C12 (0.48 g, yield: 51%) as a dark red solid, which is the alkylpyridine salt type aggregation-induced emission compound.

[0064] The chemical structure of compound C12 was characterized as shown in Figures 4-6 , to obtain characterization data: 1H NMR (600 MHz, DMSO-d6) δ 8.83 (d, J = 6.5 Hz, 2H), 8.19 (d, J = 6.8 Hz, 2H), 8.00 (d, J = 16.2 Hz, 1H), 7.76 (d, J = 8.5 Hz, 2H), 7.72 (d, J = 8.2 Hz, 2H), 7.58 - 7.55 (m, 2H), 7.50 (d, J = 16.2 Hz, 1H), 7.02 (d, J = 8.9 Hz, 4H), 6.90 (d, J = 9.0 Hz, 4H), 6.80 (d, J = 8.7 Hz, 2H), 4.23 (s, 3H), 3.91 (t, J = 6.5 Hz, 4H), 1.69 - 1.65 (m, 4H), 1.37 (d, J = 7.6 Hz, 4H), 1.22 (s, 32H), 0.83 (t, J = 7.1 Hz, 6H). 13 C NMR (151 MHz, CDC13) δ 167.74, 155.76, 155.54, 149.00, 144.82, 141.71, 140.16, 132.53, 132.18, 130.93, 130.64, 129.12, 128.82, 127.37, 126.91, 126.69, 126.63, 126.59, 123.88, 115.30, 115.25, 68.24, 65.57, 31.91, 30.55, 29.67, 29.63, 29.61, 29.59, 29.43, 29.35, 26.08, 26.07, 22.68, 19.17, 14.13, 13.72. HRMS (ESI): m / z calcd for C 56 H 75 N2O2[M-I - ] + : 807.5823, found: 807.5809.

[0065] The synthetic reaction formula of compound C12 is as follows:

[0066]

[0067] Example 2

[0068] A preparation method of an alkyl pyridine salt type aggregation-induced emission compound, which is different from example 1 only in that the amount of compound D and 1,4-dimethylpyridine-1-iodide in step (4) is different. In this example, the molar ratio of compound D and 1,4-dimethylpyridine-1-iodide is 1:2, compound D is (0.72g, 1.00mmol), and 1,4-dimethylpyridine-1-iodide is (0.46g, 2.00mmol).

[0069] Example 3

[0070] Characterization of the photophysical properties of alkylpyridinium salt type aggregation-induced emission compounds:

[0071] The compound C12 prepared in Example 1 was dissolved in DMSO (dimethyl sulfoxide) solution to prepare a 10 μM solution for testing. Figure 7 As shown, the maximum absorption wavelength of compound C12 is around 450 nm.

[0072] Then, the target compound C12 was dissolved in DMSO / Toluene (dimethyl sulfoxide / toluene) mixed solutions of different solvent volume ratios to prepare solutions of a fixed concentration (10 μM). Its fluorescence emission spectrum at an excitation wavelength of 460 nm was then detected.

[0073] like Figure 8 , 9 As shown, compound C12 exhibits very weak fluorescence intensity in DMSO solution. When the toluene volume content in the mixed solution is less than 90%, the solution shows almost no fluorescence, indicating that no aggregates are generated. When the toluene volume content reaches 90%, compound C12 begins to aggregate, and the fluorescence intensity significantly increases. When the toluene volume content is 99%, the fluorescence intensity of the solution reaches its maximum, indicating that compound C12 possesses typical and excellent aggregation-induced emission properties.

[0074] Figure 8 The fluorescence emission peak is located at 700 nm, which is in the near-infrared fluorescence range. Therefore, alkylpyridinium salt type aggregation-induced emission compounds exhibit near-infrared fluorescence emission.

[0075] Example 4

[0076] Alkylpyridine salt type aggregation-induced emission compounds are used to generate reactive oxygen species:

[0077] Using 2,7-dichlorofluorescein diacetate (DCFH-DA) as the ROS indicator, ROS generation of C12 was measured under white LED light. DCFH-DA (2 mL, 5 μM) PBS solution was added to 20 μL of 1 mM C12 DMSO dye solution. PL spectra (λ) of DCFH-DA before and after white LED light irradiation at different irradiation times were collected. ex =485nm). The fluorescence intensity at 525nm was plotted as a function of irradiation time to represent the ROS generation rate.

[0078] A control group was formed by using commercial dye Ce6 instead of C12, while another control group was formed without the addition of C12 dye to allow for adaptation.

[0079] likeFigure 10 As shown, with the increase of illumination time, compared with DCFH-DA alone, the fluorescence of DCFH-DA in the presence of C12 shows a significant increasing trend, indicating the generation of reactive oxygen species. This demonstrates that C12 in Example 1 has a strong reactive oxygen species generating ability. It can also be seen that C12 generates reactive oxygen species better than the commercial dye Ce6. C12 can be used as a very good fluorescent probe photosensitizer for photodynamic therapy.

[0080] Example 5

[0081] Alkylpyridine salt type aggregation-induced emission compounds are used to generate singlet oxygen ( 1 O2):

[0082] Using 9,10-anthratridiyl-bis(methylene)dicarboxylic acid (ABDA) as 1 O2 indicator. In the experiment, 13 μL of ABDA stock solution (7.5 mM) was added to 2 mL of C12 aqueous suspension (10 μM), and a white LED lamp was used as the irradiation source. The absorption of ABDA at 378 nm was recorded at different irradiation times to obtain the attenuation rate of the photosensitization process.

[0083] A control group was formed by using commercial dye Ce6 instead of C12, while another control group was formed without the addition of C12 dye to allow for adaptation.

[0084] like Figure 11 As shown, with increasing illumination time, compared to the control group ABDA, the UV absorption of the C12 and ABDA indicator groups continuously decreased, indicating that more... 1 O2 is generated and destroys the indicator, and it can be seen that C12 has a better ability to generate singlet oxygen than the commercial dye Ce6.

[0085] Example 6

[0086] Alkylpyridinium salt type aggregation-induced emission compounds combined with photodynamic antibacterial activity assay: Using *Pseudomonas syringae*, *Pseudomonas aeruginosa*, and *Staphylococcus aureus* as research subjects, the photodynamic antibacterial effect of fluorescent groups (AIEgens) with AIE effect was evaluated using the plate coating method. The specific steps included:

[0087] (1) Inoculate single colonies of *Pseudomonas syringae*, *Pseudomonas aeruginosa*, or *Staphylococcus aureus* isolated from LB agar plates into 5-10 mL of LB solution and incubate at 26°C (*Pseudomonas syringae*, *Pseudomonas aeruginosa*) or 37°C (*Staphylococcus aureus*) at 200 rpm for 10-12 h. Then centrifuge at 6500 rpm for 3 min, wash three times with 1×PBS (pH = 7.4), and then serially dilute in 1×PBS to achieve the desired bacterial concentration or optical density (OD) at 600 nm. Specifically, OD0.05 = 0.05%. 600 =0.3.

[0088] (2) The 40 μM, 1×PBS solution of C12 prepared in Example 1 was mixed with bacterial suspensions of Pseudomonas syringae, Pseudomonas aeruginosa, or Staphylococcus aureus (OD200). 600 =0.3) Mix thoroughly. Then divide each C12-treated bacterial suspension into two groups. One group was placed in the dark, and the other group was placed at 32 mW / cm². 2 Irradiate with white light for 1 hour. The treated bacterial suspension is then diluted 10⁻⁶ with 1×PBS. 3 Take 100 μL of each sample and spread it evenly on LB agar plates (three copies). Incubate at 26°C (for *Pseudomonas syringae* and *Pseudomonas aeruginosa*) or 37°C (for *Staphylococcus aureus*) for 24 hours. Count the bacterial colonies and calculate the colony-forming unit (CFU) survival rate using the following formula:

[0089]

[0090] In the formula, A0 is the CFU count of 1x PBS, and A is the CFU count of the experimental group (C12) under darkness or white light irradiation.

[0091] from Figures 12-13 As can be seen, in the group without C12 treatment, *Pseudomonas syringae*, *Pseudomonas aeruginosa*, and *Staphylococcus aureus* grew well on the agar plates under both dark and light conditions; C12 treatment alone had no significant antibacterial effect on *Pseudomonas syringae*, *Pseudomonas aeruginosa*, and *Staphylococcus aureus*; in the group treated with both C12 and light, there were almost no visible colonies of *Pseudomonas syringae*, *Pseudomonas aeruginosa*, and *Staphylococcus aureus* on the agar plates, with a colony count reduction of nearly 100%, indicating that C12 can kill Gram-positive and Gram-negative bacteria through photodynamic therapy.

[0092] Example 7

[0093] Bacterial viability assays of alkylpyridine salt-type aggregation-induced luminescence compounds:

[0094] Calcein-am is a membrane-permeable dye that can be used as a marker for live cells. Once inside the cell, intracellular esterases cleave the acetoxy methyl group (am) to convert it to calcein, a fluorescent dye that cannot permeate the membrane. Propidium iodide (PI) is used to stain DNA and RNA of dead bacterial cells. Bacterial viability test was performed using Calcein-am and PI double-staining fluorescent dyes to assess the integrity of the membrane.

[0095] Bacterial suspensions were prepared with 1 x PBS at a concentration of 1 x 10 6 mL -1 Bacterial suspensions of P. aeruginosa, P. aeruginosa or S. aureus were mixed with 40 mM of C12 prepared in Example 1 in 1 x PBS following the method of Example 5 and mixed thoroughly. A mixture of Calcein-am (4 mM) and PI (6 mM) was added to 100 pL of the bacterial suspension mixed with C12. The solution was incubated in the dark for 15 min. After staining, the samples were washed with 1 x PBS to remove excess dye. Subsequently, the bacteria were imaged using a 20x magnification with a Leica TCS SP8 CLSM (Leica Microsystems, Heidelberg, Germany).

[0096] As shown in Figure 14 , confocal laser scanning microscopy (CLSM) results showed that bacteria treated with C12 mainly emitted green fluorescence in the dark, indicating a high proportion of live bacteria. While bacteria treated with white light and C12 mainly emitted red fluorescence, indicating a large number of dead bacteria. These observations indicate that AIEgens exhibit bactericidal activity under white light irradiation.

[0097] The above is only an example and description of the present application, those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace, as long as it does not deviate from the structure of the present application or exceed the scope defined by the present claims, it should belong to the protection scope of the present application.

Claims

1. An alkylpyridinium salt type aggregation-induced emission compound, characterized by, The molecular structure is as follows: 。 2. The alkylpyridinium salt type aggregation-induced emission compound according to claim 1, characterized in that: The alkyl pyridine salt type aggregation-induced emission compound has near-infrared fluorescent emission.

3. A method for producing the alkylpyridinium salt type aggregation-induced emission compound according to claim 1 or 2, characterized by, The method comprises the following steps: stirring and refluxing raw material D and 1,4-dimethylpyridine-1-iodide, anhydrous ethanol and piperidine overnight, after the reaction mixture is cooled, it is concentrated under reduced pressure, and the crude product is purified by elution to obtain the alkyl pyridine salt type aggregation-induced emission compound; The structure of the raw material D is as follows: 。 4. The method for preparing an alkylpyridinium salt type aggregation-induced emission compound according to claim 3, characterized in that: The molar ratio of the raw material D and 1,4-dimethylpyridine-1-iodide is 1:1-1:

2.

5. The method for preparing an alkylpyridinium salt type aggregation-induced emission compound according to claim 3, characterized in that: The preparation method of the raw material D comprises the following steps: mixing raw material C, 1-bromododecane, KI and K2CO3 with acetonitrile under nitrogen, stirring and refluxing overnight, after cooling to room temperature, extracting the reaction mixture with water and dichloromethane, then drying and concentrating, and purifying the crude product by silica gel elution chromatography with a mixed solution of petroleum ether and ethyl acetate to obtain the raw material D; The structure of the raw material C is as follows: 。 6. The method for preparing an alkylpyridinium salt type aggregation-induced emission compound according to claim 5, characterized in that: The preparation method of the raw material C comprises the following steps: adding raw material B, 4-formylphenylboronic acid, Pd(dppf)Cl2 and K2CO3 into anhydrous toluene / methanol solution under nitrogen, stirring at 90-110 DEG C overnight, after cooling to room temperature, extracting the solution with water and dichloromethane, drying and concentrating, and purifying the crude product by silica gel elution chromatography with a mixed solution of petroleum ether and dichloromethane to obtain the raw material C; The structure of the raw material B is as follows: 。 7. The method for preparing an alkylpyridinium salt type aggregation-induced emission compound according to claim 6, characterized in that: The preparation method of the raw material B comprises the following steps: dissolving A in chloroform under ice bath condition, adding a mixed solution of dichloromethane and boron tribromide dropwise into the mixture, then reacting at room temperature for 16-18 hours, adding methanol dropwise to quench excess boron tribromide, after cooling to room temperature, extracting the reaction mixture with ethyl acetate, washing the organic layer with saturated sodium bicarbonate and water, drying and concentrating, and purifying the crude product by column chromatography with a mixed solution of petroleum ether and ethyl acetate to obtain the raw material B; The structure of the raw material A is as follows: 。 8. Use of the alkylpyridinium salt type aggregation-induced emission compound according to claim 1, characterized in that: The alkyl pyridine salt type aggregation-induced emission compound is used for generating active oxygen and singlet oxygen under light irradiation.

9. Use of an alkylpyridinium salt type aggregation-induced emission compound according to claim 8, characterized in that: The alkyl pyridine salt type aggregation-induced emission compound is used for preparing a fluorescent probe photosensitizer for photodynamic therapy.

10. Use of the alkylpyridinium salt type aggregation-induced emission compound according to claim 1, characterized in that: The alkyl pyridine salt type aggregation-induced emission compound is used for preparing a bactericide for killing gram-positive bacteria and gram-negative bacteria through photodynamic action.

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