An electron donor-dual acceptor type fluorescent compound, and a preparation method and application thereof

Abstract

The application belongs to the technical field of organic synthesis, and relates to an electron donor-dual acceptor type fluorescent compound and a preparation method and application thereof, and has the following structural formula: wherein R1 is at least one of the following functional groups: R2 is H, -CH3, -COOCH2CH3, -COOCH3 or -NO2; X1 is a halogen ion; the preparation method comprises the following steps: mixing a compound as shown in formula 2 with a compound as shown in formula 3 and an organic base, and performing a Brain Coupling reaction to obtain the electron donor-dual acceptor type fluorescent compound. Compared with the prior art, the photosensitizer structure of the application can efficiently generate reactive oxygen, and exhibits a high-efficiency photodynamic killing effect on methicillin-resistant Staphylococcus aureus and Escherichia coli. These characteristics make the donor-dual acceptor pyridine salt derivative have important application value in the development of novel antibacterial materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic synthesis, and relates to a fluorescent compound of an electron donor-dual acceptor (A-D-A) type, a preparation method and application thereof, in particular to a fluorescent compound of an electron donor-dual acceptor type, a preparation method and application thereof in preparation of an antibacterial reagent. BACKGROUND

[0002] Bacteria, as the largest group of organisms on earth, play an active role in the fields of food industry (such as fermentation), biotechnology (such as biofuel production), medicine (such as the development of antibiotics and vaccines), and so on. They have a profound impact on human society, but also pose a significant threat to human health. In recent years, the development of new antibiotics has far failed to keep pace with the development of drug resistance, and traditional antibiotic development channels have almost dried up. Therefore, developing new strategies and treatment methods that can effectively combat drug-resistant bacterial infections has become a global research focus.

[0003] Photodynamic therapy (PDT) is a non-invasive innovative treatment method that has attracted more and more attention from scientific researchers and medical workers. Among the several key factors of photodynamic therapy, photosensitizers (PSs) are the most important component. Photodynamic therapy (PDT) uses a specific wavelength of excitation light to activate photosensitizers (PSs) to produce reactive oxygen species (ROS), thereby killing microorganisms or inducing apoptosis. Due to its non-contact, convenience, low risk, and broad-spectrum antimicrobial properties, it is widely considered as a promising method for treating various tumors and bacterial infections. However, due to the limited penetration depth of light into tissues, its effectiveness in treating deep pathological tissues is limited.

[0004] Recent studies have shown that near-infrared (NIR) light exhibits a special tissue penetration ability while minimizing collateral damage to normal cells, thereby providing significant benefits and driving the advancement of NIR light-excited photosensitizers. Therefore, near-infrared photosensitizers are an effective tool for improving the treatment depth of photodynamic therapy. SUMMARY

[0005] The purpose of the present application is to provide a fluorescent compound of an electron donor-dual acceptor type, a preparation method and application thereof. The photosensitizer structure of the present application can efficiently produce reactive oxygen species and exhibit a high photodynamic killing effect on methicillin-resistant Staphylococcus aureus (gram-positive bacteria) and Escherichia coli (gram-negative bacteria). These characteristics make the donor-dual acceptor pyridine salt derivative have important application value in the development of new antibacterial materials.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] The first aspect of the present application provides an electron donor-dual acceptor type fluorescent compound, having the following structural formula:

[0008]

[0009] R1 is at least one of the following functional groups:

[0010]

[0011] R2 is H, -CH3, -COOCH2CH3, -COOCH3 or -NO2;

[0012] X1 is a halogen ion.

[0013] The electron donor-dual acceptor type fluorescent compound provided by the present application takes pyridine salt as an electron donor group, which provides multiple advantages for antibacterial application in the design of fluorescent materials, including enhanced water solubility and bacterial adsorption capacity, excellent photo-physical and chemical properties, bacterial responsiveness, photosensitizer activity, and the potential to optimize performance through structural modification. These characteristics make pyridine salt derivatives important in the development of new antibacterial materials and enable the regulation of the optical properties of target compounds in solution. The compound of the present application belongs to the A-D-A type structure, which promotes red-shifted absorption and emission wavelength by enhancing intramolecular charge transfer (ICT), reduces the singlet-triplet energy gap, promotes intersystem crossing, and thus activates the photodynamic performance.

[0014] Further, R1 is

[0015] Further, R2 is -NO2.

[0016] Further, X1 is bromide and / or iodide.

[0017] Further, the compound has the following structural formula:

[0018]

[0019] The second aspect of the present application provides a preparation method of an electron donor-dual acceptor type fluorescent compound, comprising the following steps:

[0020]

[0021] The compound as shown in formula 2 is mixed with the compound as shown in formula 3 and an organic base, and a Brain Coupling reaction is performed to obtain the electron donor-dual acceptor type fluorescent compound.

[0022] Further, the preparation method of the compound as shown in formula 2 comprises:

[0023]

[0024] The phenolic compound as shown in Formula 1 and hexamethylenetetramine (HMTA) are mixed and subjected to a Williamson synthesis reaction.

[0025] Further, in the Williamson synthesis reaction, the reaction conditions include at least one of the following conditions:

[0026] A) the molar ratio of the phenolic compound, hexamethylenetetramine is 1: (2.0-2.5);

[0027] B) the reaction temperature is 100-120°C, and the reaction time is 20-24h;

[0028] C) the reaction solvent is trifluoroacetic acid (TFA).

[0029] Further, the preparation method of the compound as shown in Formula 3 includes: heating 4-methylpyridine and X1-R1.

[0030] Further, in the heating reaction, the reaction conditions include at least one of the following conditions:

[0031] A) the molar ratio of the 4-methylpyridine and the R1 group in X1-R1 is 1: (1-1.5);

[0032] B) the reaction temperature is 80-95°C, and the reaction time is 12-24h;

[0033] C) the reaction solvent is acetonitrile (ACN).

[0034] Further, the molar ratio of the compound as shown in Formula 2 and the compound as shown in Formula 3 is 1: (1.8-2.0); and the molar ratio of the compound as shown in Formula 2 and the organic base is 1: (2.0-2.5).

[0035] Further, in the Brainwald reaction, the reaction temperature is 80-90°C, and the reaction time is 1-3h.

[0036] In some specific embodiments,

[0037]

[0038] The preparation method of the electron donor-dual acceptor type fluorescent compound includes the following steps:

[0039] S1: the phenolic compound as shown in Formula 1 and HMTA are added to an organic solvent TFA, and heated under a protective atmosphere overnight; after the reaction is completed, dilute hydrochloric acid solution is added and heated under a protective atmosphere, and a compound as shown in Formula 2 is obtained through a Williamson synthesis reaction;

[0040] S2: mixing 4-methylpyridine with X1-R1, organic solvent ACN, under a protective atmosphere, refluxing for 24h to obtain a compound as shown in formula 3;

[0041] S3: mixing the compound as shown in formula 2, the compound as shown in formula 3, and organic base piperidine, and heating to obtain an electron donor-dual acceptor type fluorescent compound through a brain green reaction.

[0042] The third aspect of the present application provides an application of an electron donor-dual acceptor type fluorescent compound, comprising using the electron donor-dual acceptor type fluorescent compound to prepare an antibacterial reagent.

[0043] Further, the electron donor-dual acceptor type fluorescent compound is used as a photosensitizer for photodynamic therapy, and the photodynamic killing effect on methicillin-resistant Staphylococcus aureus and Escherichia coli is obvious.

[0044] The present application proposes a new type of electron donor-dual acceptor type fluorescent molecular compound, and particularly emphasizes the characteristics based on the donor-acceptor structure and the application potential in fluorescent detection technology. The fluorescent molecule has excellent performance, can realize internal charge transfer, form a long π-electron system, and emit fluorescence in the near-infrared region, and is suitable for in vivo imaging. The new photosensitizer (PSs) has a propeller configuration, and this design effectively replaces the toxic inorganic nano photosensitive material, and the propeller configuration inhibits the fluorescence quenching phenomenon. By enhancing the intramolecular charge transfer (ICT), the red shift of the absorption and emission wavelength can be promoted, and the energy gap between the singlet state and the triplet state is reduced, so that the photodynamic performance is improved. Especially noteworthy is that the compound contains a pyridine salt, which provides many advantages in antibacterial applications, such as improved water solubility and bacterial adsorption capacity, excellent photo-physical and chemical properties, bacterial responsiveness, and photosensitizer activity. In addition, through structural modification, the potential for optimizing performance is also obvious.

[0045] Compared with the prior art, the present application has the following characteristics:

[0046] 1) The present application simply and efficiently synthesizes A-D-A type symmetrical structure compounds by a brain green reaction of a pyridine salt and 2-hydroxyisophthalaldehyde and its derivatives. The compounds promote the red shift of the absorption and emission wavelength by enhancing the intramolecular charge transfer (ICT). These characteristics make the pyridine salt derivative have important value in the development of new antibacterial materials;

[0047] 2) The present application finds through active oxygen testing that the group on the donor enhances the generation of singlet state with the enhancement of its electron-withdrawing ability, and the antibacterial effect is best;

[0048] 3) The present application provides a class of pyridine salt cations as electron donor groups, enhanced water solubility and bacterial adsorption capacity, excellent photo-physical and chemical properties, bacterial responsiveness, photosensitizer activity, and the potential to optimize performance through structural modification;

[0049] 4) The compound provided by the present application can selectively respond to gram-negative bacteria, and has certain antibacterial effect on gram-positive bacteria. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 (A) and Figure 1 The UV-Vis absorption spectrum of the fluorescent compounds D01-D12 and D13-D33 prepared in Example 2 is shown in (B);

[0051] Figures 2-5 The change of the absorbance value of the mixture solution of fluorescent compound D01, D03, D13 and D28 with singlet oxygen trapping agent DPBF at 412 nm with light irradiation time is shown in (A) and (B), respectively;

[0052] Figure 6 The change of the absorption spectrum of the singlet oxygen trapping agent DPBF solution with light irradiation time is shown in (A) and (B), respectively;

[0053] Figure 7 The change of the absorbance of the UV-Vis absorption spectrum of fluorescent compound D28, DPBF and compound RB at 412 nm with light irradiation time is shown in (A) and (B), respectively. DETAILED DESCRIPTION

[0054] The present application will be described in detail below in conjunction with the drawings and specific examples. The present embodiment is implemented on the basis of the technical solution of the present application, and detailed implementation and specific operation process are given, but the protection scope of the present application is not limited to the following examples.

[0055] The following are more detailed implementation cases, which further illustrate the technical solution of the present application and the technical effects that can be obtained.

[0056] In the following examples, unless otherwise specified, the raw materials and reagents or processing techniques are all conventional commercially available products or conventional processing techniques in the art.

[0057] Example 1: Synthesis of starting compound

[0058]

[0059] A starting compound A, the preparation method thereof comprises:

[0060] 4-Methylpyridine (20 mmol, 1.8626 g) and (3-bromopropyl)trimethylammonium bromide (16 mmol, 1.044 g) were added to a reaction flask, followed by 10 mL of anhydrous acetonitrile (ACN). The reaction was heated to 80 °C under N2 protection and refluxed for 24 h. After the reaction was completed, the mixture was cooled to room temperature, and the reaction solution was added dropwise to 20 mL of ethyl acetate solution. After standing for half an hour, a large amount of white solid precipitated. The solid was filtered, washed several times with ethyl acetate, and dried to obtain compound A (white solid, 5.45 g, yield: 76.96%).

[0061] The proton NMR spectrum is 1 H NMR(500MHz,Deuterium Oxide)δ8.62(d,J=6.8Hz,2H),7.85(d,J=6.3Hz,2H),4.58(t,J=7.6Hz,2H),3.59–3.22(m,2H),3.09(s,9H),2.59(s,3H),2.55–2.26(m,2H).

[0062] In this embodiment, the following compounds were synthesized by replacing (3-bromopropyl)trimethylammonium bromide with the corresponding compound in the reaction equation in equal molar amounts and using the same method (unless otherwise specified, the remaining preparation steps and conditions for the following compounds are the same as those for compound A):

[0063] Synthesis of starting compound B

[0064]

[0065] The proton NMR spectrum is 1 H NMR(500MHz,DMSO-d6)δ9.06(d,J=6.7Hz,2H),8.03(d,J=6.9Hz,2H),4.63(t,J=7.3Hz,2H),3.35(dd,J=8.1,4 .1Hz,2H),3.09(s,9H),2.62(s,3H),2.02–1.92(m,2H),1.75(dq,J=12.1,6.4,4.9Hz,2H),1.33–1.22(m,2H).

[0066] Synthesis of starting compound C

[0067]

[0068] The proton NMR spectrum is 1H NMR (500 MHz, DMSO-d6) δ 9.06 (d, J = 6.8 Hz, 2H), 8.02 (d, J = 6.2 Hz, 2H), 4.60 (t, J = 7.4 Hz, 2H), 3.38 - 3.32 (m, 2H), 3.09 (s, 9H), 2.62 (s, 3H), 1.93 (t, J = 7.4 Hz, 2H), 1.69 (td, J = 9.4, 8.0, 4.3 Hz, 2H), 1.32 (dd, J = 6.9, 3.5 Hz, 4H).

[0069] Synthesis of starting compound D

[0070]

[0071] NMR hydrogen spectrum of starting compound D is 1 H NMR (500 MHz, DMSO-d6) δ 8.92 (d, J = 6.8 Hz, 2H), 7.98 (d, J = 7.0 Hz, 2H), 4.61 (t, J = 7.1 Hz, 2H), 3.44 (td, J = 5.9, 4.8 Hz, 2H), 2.61 (s, 3H), 2.10 - 1.98 (m, 2H).

[0072] Synthesis of starting compound F

[0073]

[0074] 4-methylpyridine (5.0 mmol, 0.49 ml), 1,3-dibromopropane (20 mmol, 2.04 mL) were added to the reaction bottle, 10 mL of anhydrous acetonitrile was added, the reaction mixture was refluxed for 4 h, after the reaction was completed, the reaction liquid was cooled to room temperature, the solvent was removed by vacuum evaporation, ethyl acetate was added to the remaining liquid, precipitates were precipitated, then the precipitates were filtered, washed with ethyl acetate for several times, and dried to obtain product E (white solid, yield 92.46%).

[0075] Compound E (2.05 mmol, 604.79 mg), NaN3(5.13 mmol, 333.18 mg) were added to the reaction bottle, then 10 mL of acetonitrile was added, refluxed for 16 h, after the reaction was completed, the reaction liquid was cooled to room temperature, the solution was spin-dried, washed with DCM and spin-dried again, and the solvent was spin-evaporated to obtain compound F (0.945 g, yield: 89.66%).

[0076] NMR hydrogen spectrum of starting compound F is 1H NMR (500 MHz, DMSO-d6) δ 9.04 (d, J = 6.7 Hz, 2H), 8.03 (d, J = 7.0 Hz, 2H), 4.67 (t, J = 7.2 Hz, 2H), 3.48 (t, J = 6.6 Hz, 2H), 2.62 (s, 3H), 2.23 - 2.14 (m, 2H).

[0077] Synthesis of starting compound 11

[0078]

[0079] The nuclear magnetic resonance hydrogen spectrum of starting compound 11 is 1H NMR (500 MHz, DMSO-d6) δ = 8.97 (2H, d, J = 6.8 Hz), 8.04 (2H, d, J = 6.8), 4.7 (2H, t, J = 6.8 Hz), 3.06 (1H, t, J = 2.4 Hz), 2.95 (2H, dt, J = 6.8, 2.4 Hz), 2.62 (3H, s).

[0080] Synthesis of starting compound 13

[0081]

[0082] Compound 3-methylthiopropyl alcohol (5.8 mmol, 615.90 mg) was dissolved in anhydrous ether, the mixed solution was cooled to 0°C under nitrogen protection, PBr3(2.3 mmol, 622.59 mg) was slowly added for 30 min, the mixture was warmed to room temperature and stirred overnight, the reaction was completed, the reaction mixture was cooled to 0°C, and 10 mL of water was slowly added, the organic phase was separated, washed with saturated NaHCO3and brine, dried over anhydrous sodium sulfate, and then the organic phase was rotary evaporated, and the obtained product was directly subjected to the next step reaction with 4-methylpyridine.

[0083] The nuclear magnetic resonance hydrogen spectrum of starting compound 13 is 1 H NMR (500 MHz, DMSO-d6) δ 9.01 (d, J = 6.8 Hz, 2H), 8.01 (d, J = 6.2 Hz, 2H), 4.64 (t, J = 7.3 Hz, 2H), 2.62 (s, 3H), 2.57 - 2.42 (m, 2H), 2.20 (p, J = 7.3 Hz, 2H), 2.06 (s, 3H).

[0084] Synthesis of starting compound K

[0085]

[0086] The nuclear magnetic resonance hydrogen spectrum is 1H NMR (500 MHz, Chloroform-d) δ 9.34 (d, J = 6.8 Hz, 2H), 7.80 (d, J = 8.1 Hz, 2H), 7.76 (d, J = 6.3 Hz, 2H), 7.60 (d, J = 8.1 Hz, 2H), 6.24 (s, 2H), 2.59 (s, 3H), 1.32 (s, 12H).

[0087] Example 2: Synthesis of fluorescent compound

[0088]

[0089] Synthesis of fluorescent compound D01, comprising the following steps:

[0090] S1 : Phenol (28.68 mmol, 2.6991 g), hexamethylenetetramine (HMTA, 57.37 mmol, 8.04 g) were added to a reaction flask, 30 mL of trifluoroacetic acid (TFA) was added, the temperature was raised to 120 °C, and the reaction was allowed to proceed for 20 h. After the reaction was completed, the oil bath temperature was reduced to 100 °C, 50 mL of a 3 M HC1 solution was quickly added, and the reflux was continued for 1 h, after which the solution was slowly cooled to room temperature. A large amount of yellow precipitate appeared, which was filtered, washed several times with distilled water, and dried to obtain intermediate compound a (light yellow solid powder, 2.5803 g, yield: 59.93%).

[0091] S2: 4-Methylpyridine (20 mmol, 1.8626 g) and (3-bromopropyl)trimethylammonium bromide (16 mmol, 1.044 g) were added to a reaction flask, 10 mL of anhydrous acetonitrile was added, and the reaction was allowed to proceed at 80 °C under N2protection for 24 h. After the reaction was completed, the solution was cooled to room temperature, and the reaction solution was added dropwise to 20 mL of an ethyl acetate solution. After standing for half an hour, a large amount of white solid precipitated, which was filtered, washed several times with ethyl acetate, and dried to obtain starting compound A (white solid, 5.45 g, yield: 76.96%).

[0092] S3: Compound a (0.45 mmol, 67.56 mg) and starting compound A (0.9 mmol, 318.72 mg) were added to a reaction flask, 3 mL of anhydrous ethanol was added, and piperidine (0.9 mmol, 90 μί) was added under N2protection. The reaction was allowed to proceed at 80 °C for 1 h. After the reaction was completed, the solution was cooled to room temperature, and the reaction solution was added dropwise to ethyl acetate. After standing for 1 h, the precipitate was filtered, washed several times with ethyl acetate, and dried to remove the ethyl acetate (deep purple solid, 172.80 mg, yield: 46.69%).

[0093] Nuclear magnetic resonance hydrogen spectrum is 1H NMR (500 MHz, DMSO-d6) δ 8.75 (d, J = 6.6 Hz, 4H), 8.11 (d, J = 15.7 Hz, 2H), 8.04 (d, J = 6.5 Hz, 4H), 7.87 (d, J = 15.7 Hz, 2H), 7.46 (d, J = 7.6 Hz, 2H), 4.50 (t, J = 7.4 Hz, 4H), 3.44 (m, 4H), 2.47 - 2.37 (m, 4H).

[0094] NMR (126 MHz, DMSO-d6) δ 156.05, 155.45, 144.04, 142.66, 126.91, 126.15, 122.86, 119.92, 119.72, 62.34, 56.39, 44.15, 24.69. 13 C NMR (126 MHz, DMSO-d6) δ 156.05, 155.45, 144.04, 142.66, 126.91, 126.15, 122.86, 119.92, 119.72, 62.34, 56.39, 44.15, 24.69.

[0095] HRMS (ESI) m / z [M+H]+calcd for C40H32BF2N5S4+, 759.1716; found, 759.1665.

[0096] This example also synthesizes the following compounds by replacing the starting compound A with an equimolar amount of the corresponding starting compound in Table 1, by replacing the corresponding intermediate compound a with an equimolar amount of the corresponding intermediate compound in Table 1, using the same method (except where specifically indicated, the remaining preparation steps and conditions for the following compounds are the same as those for the preparation of fluorescent compound D01):

[0097]

[0098] NMR (126 MHz, DMSO-d6) δ 156.05, 155.45, 144.04, 142.66, 126.91, 126.15, 122.86, 119.92, 119.72, 62.34, 56.39, 44.15, 24.69. 1 H NMR (500 MHz, DMSO-d6) δ 8.77 (d, J = 6.4 Hz, 4H), 8.10 (d, J = 15.7 Hz, 2H), 8.05 (d, J = 6.5 Hz, 4H), 7.82 (d, J = 15.7 Hz, 2H), 7.36 (s, 2H), 4.51 (t, J = 7.3 Hz, 4H), 3.45 (q, J = 7.0 Hz, 4H), 3.12 (s, 18H), 2.49 - 2.38 (m, 4H), 2.20 (s, 3H).

[0099] Fluorescent compound D03 is synthesized

[0100]

[0101] NMR (126 MHz, DMSO-d6) δ 156.05, 155.45, 144.04, 142.66, 126.91, 126.15, 122.86, 119.92, 119.72, 62.34, 56.39, 44.15, 24.69. 1H NMR(500MHz,DMSO-d6)δ8.81(d,J=6.8Hz,4H),8.11(d,J=6.8Hz,2H),8.05(d,J= 15.6Hz,4H),7.97(s,2H),3.77(s,4H),3.50–3.41(m,3H),2.44(p,J=7.7Hz,4H).

[0102] The carbon NMR spectrum is 13 C NMR (126MHz, DMSO-d6) δ178.16,166.86,156.33,143.82,143.36,137.06,125.74,122.61,119.27,109.62,62.30,56.23,52.94,51.53,24.65.

[0103] High-resolution mass spectrometry was performed using HRMS (ESI) m / z [M / 4]. 4+ Calculation result for C34H48N4O34+: Theoretical value: 140.0926; Measured value: 140.0926.

[0104] Synthesis of fluorescent compound D04

[0105]

[0106] The proton NMR spectrum is 1 H NMR(500MHz,DMSO-d6)δ8.07(d,J=6.7Hz,4H),8.06–8.00(m,4H),7.98(d,J=14.0Hz,4H),4.49(t,J=7.3H z,2H),3.38–3.30(m,4H),3.09(s,18H),1.95(p,J=7.4Hz,4H),1.81–1.72(m,4H),1.30(p,J=7.1Hz,4H).

[0107] The carbon NMR spectrum is 13 C NMR (126MHz, DMSO-d6) δ177.99,166.89,156.00,143.72,143.03,136.76,125. 70,122.61,119.22,109.61,65.33,58.87,49.25,44.16,30.35,22.62,22.00.

[0108] High-resolution mass spectrometry (HRMS(ESI)) m / z [M / 4] 4+ calcd for C38H56N4O3 4+ was performed. The theoretical value was 154.1082, and the measured value was 154.1080.

[0109] Synthesis of fluorescent compound D05

[0110]

[0111] The proton NMR spectrum is 1 H NMR (500MHz, DMSO-d6) δ8.77(d,J=6.6Hz,4H),8.08(d,J=5.3Hz,2H),8.06(d,J=3.3Hz,4H),8.04(s,2H),7.97(s,2H),4.45( t,J=7.4Hz,4H),3.77(s,3H),3.35–3.26(m,4H),3.07(s,18H),1.91(q,J=7.3Hz,4H),1.74–1.67(m,4H),1.36–1.31(m,8H).

[0112] Carbon NMR spectrum 13 C NMR(126MHz,DMSO-d6)δ166.90,155.94,143.70,142.97,136.71,125.69,122.86, 122.59,119.21,109.57,65.57,59.16,52.64,44.19,30.64,25.41,22.65,22.31.

[0113] High-resolution mass spectrometry (HRMS(ESI)) m / z [M / 4] 4+ calcd for C40H60N4O3 4+, theoretical value 161.1161; measured value: 161.1161.

[0114] Synthesis of fluorescent compound D06

[0115]

[0116] The proton NMR spectrum is 1 H NMR(500MHz,DMSO-d6)δ8.79(d,J=6.6Hz,4H),8.05(t,J=8.9Hz,8H),7.96(s,2H),7 .74(d,J=7.7Hz,4H),7.51(d,J=7.6Hz,4H),5.69(s,4H),3.76(s,3H),1.29(s,24H).

[0117] Carbon NMR spectrum 13C NMR (126 MHz, DMSO-d6) δ 170.86, 166.87, 156.33, 143.73, 138.42, 136.95, 135.61, 135.29, 128.39, 127.87, 125.74, 122.88, 119.21, 109.83, 84.33, 60.24, 51.55, 25.09.

[0118] Mass spectrum was HRMS (ESI) m / z [M]2+calcd for C48H54B2N2O72+, 792.4106; found: 792.4135.

[0119] Synthesis of fluorescent compound D07

[0120]

[0121] NMR hydrogen spectrum was 1 H NMR (500 MHz, DMSO-d6) δ 8.69 (d, J = 6.5 Hz, 4H), 8.06 (d, J = 15.7 Hz, 2H), 7.97 (d, J = 6.4 Hz, 4H), 7.77 (d, J = 15.7 Hz, 2H), 7.32 (s, 2H), 4.47 (t, J = 7.0 Hz, 4H), 2.18 (m, J = 8.7 Hz, 8H), 2.08 (s, 6H).

[0122] NMR carbon spectrum was 13 C NMR (126 MHz, DMSO-d6) δ 155.28, 143.73, 141.11, 134.74, 128.64, 125.66, 122.49, 121.18, 119.00, 58.35, 44.21, 29.97, 20.57, 14.96.

[0123] High resolution mass spectrum was HRMS (ESI) m / z [M]2+calcd for C29H36N2OS22+, 492.2258; found: 492.2209.

[0124] Synthesis of fluorescent compound D08

[0125]

[0126] NMR hydrogen spectrum was 1H NMR (500MHz, DMSO-d6) δ8.64(d,J=6.5Hz,4H),8.05(d,J=15.6Hz,2H),7.95(d,J=6.5Hz,4H),7.85(d,J=15.7 Hz,2H),7.41(d,J=7.5Hz,2H),4.80(s,2H),4.47(t,J=7.1Hz,4H),3.48–3.43(m,4H),2.04(p,J=6.5Hz,4H).

[0127] The carbon NMR spectrum is 13 C NMR (126MHz, DMSO-d6) δ155.59, 143.72, 142.16, 142.05, 132.99, 126.17, 122.67, 122.21, 118.37, 57.61, 44.24.

[0128] High-resolution mass spectrometry (HRMS(ESI)) m / z [M]2+calcd for C26H30N2O32+ was obtained, with a theoretical value of 209.1122 and an actual value of 209.1119.

[0129] Synthesis of fluorescent compound D09

[0130]

[0131] The proton NMR spectrum is 1 H NMR (500MHz, DMSO-d6) δ8.69(d,J=6.8Hz,4H),8.05(d,J=5.1Hz,4H),8.03(d,J=2.5Hz,4H),7.96( s,2H),4.77(s,2H),4.49(t,J=7.0Hz,4H),3.77(s,3H),3.46(q,J=3.5Hz,4H),2.09–1.98(m,4H).

[0132] The carbon NMR spectrum is 13 C NMR (126MHz, DMSO-d6) δ177.94,166.91,155.82,143.87,142.78,136.55,125.68,122.50,119.21,109.60,57.60,51.51,44.18,33.64.

[0133] High-resolution mass spectrometry (HRMS(ESI)) m / z [MH]2+ calcd for C28H32N2O52+ was performed, with a theoretical value of 476.2300 and an actual measured value of 475.2237.

[0134] Synthesis of fluorescent compound D10

[0135]

[0136] The proton NMR spectrum is 1 H NMR (500MHz, DMSO-d6) δ8.63(d,J=6.5Hz,4H),8.01(d,J=15.6Hz,2H),7.90(d,J=6.5Hz,4H),7.84(d,J=1 5.6Hz,2H),7.22(s,2H),4.46(t,J=7.0Hz,4H),3.45(t,J=5.8Hz,4H),2.15(s,3H),2.02(p,J=6.4Hz,4H).

[0137] The carbon NMR spectrum is 13 C NMR (126MHz, DMSO-d6) δ155.60,144.38,143.59,142.32,135.69,125.87,121.92,118.83,117.61,57.49,44.15,33.72,22.86.

[0138] High-resolution mass spectrometry (HRMS(ESI)) m / z [M / 2]2+calcd for C27H32N2O32+ was performed, with a theoretical value of 216.1201 and an actual value of 216.1205.

[0139] Synthesis of fluorescent compound D11

[0140]

[0141] The proton NMR spectrum is 1 H NMR (500MHz, DMSO-d6) δ8.73(d,J=6.6Hz,4H),8.09(d,J=15.8Hz,2H),8.02(d,J=5.3Hz,4H),7.75(d,J=15.8 Hz,2H),7.37(s,2H),4.49(t,J=7.1Hz,4H),3.49(t,J=6.6Hz,4H),2.21(s,3H),2.18(dd,J=13.3,6.4Hz,4H).

[0142] The carbon NMR spectrum is 13 C NMR (126MHz, DMSO-d6) δ154.17,153.99,144.68,137.26,137.08,131.27,124.83,123.98,123.05,57.68,56.83,49.04,48.11,30.09,20.62.

[0143] High resolution mass spectrum was HRMS (ESI) m / z [M]2+calcd for C27H30N8O2+, 482.2532; found: 482.2482.

[0144] Synthesis of fluorescent compound D12

[0145]

[0146] NMR hydrogen spectrum was 1 H NMR (500 MHz, DMSO-d6) δ 9.53 (s, 1H), 8.77 (d, J = 6.6 Hz, 4H), 8.07 (d, J = 6.7 Hz, 4H), 8.04 (d, J = 2.4 Hz, 4H), 7.88 (d, J = 12.7 Hz, 2H), 4.52 (t, J = 7.1 Hz, 4), 3.49 (dd, J = 13.2, 4.5 Hz, 4H), 2.22 - 2.08 (m, 4H).

[0147] NMR carbon spectrum was 13 C NMR (126 MHz, DMSO-d6) δ 155.63, 143.71, 143.61, 141.98, 134.70, 126.15, 122.44, 118.70, 112.35, 56.99, 48.10, 44.18, 30.00, 22.63.

[0148] High resolution mass spectrum was HRMS (ESI) m / z [M]2+calcd for C26H28N8O2+, 468.2375; found: 482.2482.

[0149] Synthesis of fluorescent compound D13

[0150]

[0151] NMR hydrogen spectrum was 1 H NMR (500 MHz, DMSO-d6) δ 8.71 (d, J = 7.0 Hz, 4H), 8.08 (d, J = 12.0 Hz, 2H), 8.05 (d, J = 3.5 Hz, 4H), 8.04 (d, 2H), 7.97 (s, 2H), 4.48 (t, J = 7.1 Hz, 4H), 3.48 (t, J = 6.5 Hz, 4H), 2.17 (p, J = 6.8 Hz, 4H).

[0152] NMR carbon spectrum was 13C NMR(126MHz,DMSO-d6)δ170.88,166.90,156.17,155.99,143.83,142.81,1 36.48,125.69,122.66,119.32,60.25,57.12,51.56,48.08,29.96,21.23.

[0153] High-resolution mass spectrometry (HRMS(ESI)) m / z [M]2+calcd for C28H30N8O32+ was performed, with a theoretical value of 526.2430 and an measured value of 526.2371.

[0154] Synthesis of fluorescent compound D14

[0155]

[0156] The proton NMR spectrum is 1 H NMR(500MHz,DMSO-d6)δ8.43(d,J=6.1Hz,4H),7.96–7.89(m,4H),7.84(d,J=6.4Hz,4H),7.37(d,J=16.0Hz,2H),5. 26(s,2H),4.45(t,4H),4.19(q,J=7.1Hz,2H),3.44(t,J=5.8Hz,4H),2.00(p,J=6.4Hz,4H),1.26(t,J=7.1Hz,3H).

[0157] The carbon NMR spectrum is 13 C NMR (126MHz, DMSO-d6) δ178.04,166.46,155.88,143.86,142.95,136.78,125.62,122.49,119.25,109.87,59.81,57.60,57.10,33.65,15.08.

[0158] High-resolution mass spectrometry (HRMS(ESI)) m / z [M]2+calcd for C29H28N2O52+ was performed, with a theoretical value of 490.2457 and an actual measured value of 490.2435.

[0159] Synthesis of fluorescent compound D15

[0160]

[0161] The proton NMR spectrum is 1H NMR (500 MHz, DMSO-d6) δ 8.72 (d, J = 6.6 Hz, 4H), 8.08 (d, J = 15.7 Hz, 2H), 8.00 (d, J = 6.5 Hz, 4H), 7.79 (d, J = 15.7 Hz, 2H), 7.33 (s, 2H), 4.56 (t, J = 6.6 Hz, 4H), 3.08 (t, J = 2.6 Hz, 2H), 2.96 - 2.89 (m, 4H), 2.19 (s, 3H).

[0162] C NMR (126 MHz, DMSO-d6) δ 155.68, 143.78, 141.60, 135.12, 128.38, 125.74, 122.17, 118.90, 79.98, 57.21, 49.05, 22.67, 20.71. 13 C NMR (126 MHz, DMSO-d6) δ 155.68, 143.78, 141.60, 135.12, 128.38, 125.74, 122.17, 118.90, 79.98, 57.21, 49.05, 22.67, 20.71.

[0163] HRMS (ESI) m / z [M]2+calcd for C29H28N2O2+, 420.2191; found: 420.2154.

[0164] Synthesis of fluorescent compound D19

[0165]

[0166] C NMR (126 MHz, DMSO-d6) δ 155.68, 143.78, 141.60, 135.12, 128.38, 125.74, 122.17, 118.90, 79.98, 57.21, 49.05, 22.67, 20.71. 1 H NMR (500 MHz, DMSO-d6) δ 8.79 (d, J = 6.9 Hz, 4H), 8.16 (s, 2H), 8.07 (d, J = 15.8 Hz, 2H), 8.01 (d, J = 7.4 Hz, 4H), 7.75 (dd, J = 10.6, 4.2 Hz, 4H), 7.50 (d, J = 7.8 Hz, 4H), 7.37 (s, 2H), 5.69 (d, J = 13.4 Hz, 4H), 2.20 (s, 3H), 1.30 (s, 24H).

[0167] C NMR (126 MHz, DMSO-d6) δ 155.68, 143.78, 141.60, 135.12, 128.38, 125.74, 122.17, 118.90, 79.98, 57.21, 49.05, 22.67, 20.71. 13 C NMR (126 MHz, DMSO-d6) δ 155.68, 143.78, 141.60, 135.12, 128.38, 125.74, 122.17, 118.90, 79.98, 57.21, 49.05, 22.67, 20.71.

[0168] High resolution mass spectrum was HRMS (ESI) m / z [M]2+calcd for C47H54B2N2O52+, 748.4208; found: 748.4194.

[0169] Synthesis of fluorescent compound D24

[0170]

[0171] Compound D07 (0.5 mmol, 326.27 mg) was added to the reaction bottle, then 5 ml of DMF was added, then it was slowly added under nitrogen atmosphere, iodomethane (4 mmol, 567.76 mg), room temperature overnight, after the reaction was completed, the reaction liquid was slowly dropped into 15 ml of ethyl acetate solution, standing for 30 min, the precipitate was filtered, washed with ethyl acetate for several times, the compound was dried, compound 24 (yellow solid, yield: 55.42%) was obtained

[0172] NMR hydrogen spectrum was 1 H NMR (500 MHz, DMSO-d6) δ 10.08 (s, 1H), 9.03 (d, J = 6.4 Hz, 4H), 8.30 (d, J = 6.4 Hz, 4H), 8.26 (d, J = 16.1 Hz, 2H), 7.75 (s, 2H), 7.58 (d, J = 16.0 Hz, 2H), 4.67 (t, J = 7.3 Hz, 4H), 3.42 (t, J = 7.5 Hz, 4H), 2.97 (s, 12H), 2.47 (t, J = 7.4 Hz, 4H), 2.36 (s, 3H).

[0173] NMR carbon spectrum was 13 C NMR (126 MHz, DMSO-d6) δ 153.92, 153.69, 144.99, 136.24, 130.69, 129.97, 124.69, 124.32, 124.04, 59.24, 58.14, 25.01, 20.63, 14.99.

[0174] High resolution mass spectrum was HRMS (ESI) m / z [M / 4]4+calcd for C31H42N2OS24+, 130.5679; found: 130.5685.

[0175] Synthesis of fluorescent compound D25

[0176]

[0177] NMR hydrogen spectrum was 1H NMR (500MHz, DMSO-d6) δ8.74–8.67(m,4H),8.19(s,1H),7.93(d,J=6.6Hz,2H),7.90–7.82(m,4H),7.73(d,J=7.7H z,4H),7.49(d,J=7.8Hz,2H),7.44(d,J=7.8Hz,2H),7.36(d,J=7.6Hz,2H),5.64(d,J=14.2Hz,4H),1.29(s,24H).

[0178] The carbon NMR spectrum is 13 C NMR(126MHz,DMSO-d6)δ156.23,156.13,143.45,138.55,137.06,135.61,13 5.29,128.32,127.81,126.41,126.38,122.36,117.83,84.34,60.72,25.09.

[0179] High-resolution mass spectrometry (HRMS(ESI)) m / z [M]2+calcd for C46H52B2N2O52+ was performed, with a theoretical value of 367.2026 and an actual value of 367.2023.

[0180] Synthesis of fluorescent compound D27

[0181]

[0182] 1H NMR spectrum 1 H NMR(500MHz,DMSO-d6)δ10.26(s,1H),8.79(d,J=6.8Hz,4H),8.28(s,2H),8.10(d,J=6.9Hz,4H),8.0 4(d,J=9.4Hz,4H),4.80(s,2H),4.53(t,J=7.0Hz,4H),3.46(q,J=4.9,4.2Hz,4H),2.10–2.01(m,4H).

[0183] Carbon NMR spectrum 13 C NMR (126MHz, DMSO-d6) δ155.22,144.27,141.11,130.40,129.90,125.29,123.08,121.38,57.62,57.45.

[0184] Synthesis of fluorescent compound D28

[0185]

[0186] 1H NMR spectrum 1 H NMR (500MHz, DMSO-d6) δ10.26 (s, 1H), 8.89 (d, J = 6.7Hz, 4H), 8.30 (s, 2H), 8.21–8.15 (m, 4H), 8.14–8. 05(m,4H),4.57(t,J=7.4Hz,4H),3.50–3.42(m,4H),3.13(s,18H),2.45(td,J=12.1,10.0,5.9Hz,4H).

[0187] Carbon NMR spectrum 13 C NMR (126MHz, DMSO-d6) δ178.54,155.69,144.23,141.56,130.47,130.16,125.33,123.25,121.41,62.28,56.53,52.96,24.66.

[0188] Synthesis of fluorescent compound D29

[0189]

[0190] The proton NMR spectrum is 1 H NMR(500MHz,DMSO-d6)δ8.70(d,J=6.6Hz,4H),8.07–8.01(m,6H),8.00–7.95(m,4H ),4.47(t,J=7.2Hz,4H),2.50(d,J=8.3Hz,4H),2.17(t,J=7.2Hz,4H),2.07(s,6H).

[0191] The carbon NMR spectrum is as follows 13 C NMR (126MHz, DMSO-d6) δ155.38,144.18,141.30,130.41,130.02,128.50,125.30,123.19,121.39,58.67,30.18,29.96,22.63.

[0192] Synthesis of fluorescent compound D30

[0193]

[0194] The proton NMR spectrum is 1H NMR (500 MHz, DMSO-d6) δ 8.70 (d, J = 6.6 Hz, 4H), 8.03 (q, J = 7.5, 6.4 Hz, 6H), 8.01 - 7.93 (m, 4H), 4.47 (t, J = 7.2 Hz, 4H), 3.77 (s, 3H), 2.52 (d, J = 2.0 Hz, 4H), 2.17 (t, J = 7.2 Hz, 4H), 2.07 (s, 6H).

[0195] NMR carbon spectrum is 13 C NMR (126 MHz, DMSO-d6) δ 178.02, 166.89, 155.98, 143.77, 136.71, 128.46, 125.69, 122.60, 119.24, 109.60, 58.39, 51.51, 29.96, 22.75, 14.94.

[0196] Synthesis of fluorescent compound D31

[0197]

[0198] NMR hydrogen spectrum is 1 H NMR (500 MHz, DMSO-d6) δ 10.26 (s, 1H), 8.87 (d, J = 6.7 Hz, 4H), 8.29 (s, 2H), 8.17 (s, 4H), 8.15 - 8.10 (m, 2H), 8.05 (d, J = 10.3 Hz, 2H), 7.84 (d, J = 7.9 Hz, 4H), 7.45 (d, J = 8.0 Hz, 4H), 5.68 (s, 4H). 1.30 (s, 24H)

[0199] Synthesis of fluorescent compound D32

[0200]

[0201] NMR hydrogen spectrum is 1 H NMR (500 MHz, DMSO-d6) δ 10.26 (s, 1H), 8.89 (d, J = 6.6 Hz, 4H), 8.30 (s, 2H), 8.15 (d, J = 6.7 Hz, 4H), 8.08 (d, J = 13.5 Hz, 4H), 4.53 (t, J = 7.3 Hz, 4H), 3.34 (d, J = 14.9 Hz, 18H), 1.98 (dd, J = 14.0, 6.4 Hz, 41H), 1.85 - 1.61 (m, 4H), 1.45 - 1.25 (m, 4H).

[0202] Synthesis of fluorescent compound D33

[0203]

[0204] The proton NMR spectrum is 1 H NMR (500MHz, DMSO-d6) δ10.26(s,1H),8.89(t,J=7.5Hz,4H),8.29(s,2H),8.14(d,J=6.8Hz,4H),8.07(d,J=13.1 Hz,4H),4.56–4.48(m,4H),3.37–3.30(m,18H),3.08(s,4H),1.95–1.92(m,4H),1.69(s,4H),1.46–1.27(m,8H).

[0205] Based on the characterization data above, the structural formula of the obtained water-soluble photosensitizer with antibacterial activity is shown in Formula IV, denoted as D28.

[0206]

[0207] Application Examples:

[0208] This embodiment is used to characterize the performance of the above-mentioned fluorescent compounds, including:

[0209] (1) Visible light absorption properties:

[0210] Table 1

[0211]

[0212]

[0213]

[0214]

[0215] (2) Singlet oxygen generation capacity test of fluorescent compound: 30 μL of dimethyl sulfoxide (DMSO) stock solution of fluorescent compound was added to 3 mL of ethanol solution, and 150 μL of singlet oxygen scavenger DPBF stock solution was added to the above solution to make the final concentration of photosensitizer (fluorescent compound) 10. -5 The concentration of the singlet oxygen indicator was 5 times that of the photosensitizer. The absorption spectrum of the mixed solution at 412 nm was measured. Then, the mixed solution was illuminated with a 525-550 nm LED lamp (light power 400 mW), and the change in the absorption spectrum at 412 nm of the mixed solution with illumination time was measured. The group with only DPBF was used as a blank control group. The results are as follows. Figures 2-5 and Figure 6 As shown. Figure 6 This shows the variation of DPBF with illumination time.Figure 2 The absorbance value of the mixed solution with photosensitizer at 412 nm changes with the illumination time. From Figures 2-5 and Figure 6 It can be seen that with the extension of illumination time, the absorption value of the blank DPBF group has no obvious change, but the absorption value of singlet oxygen trapping agent DPBF decreases obviously in the presence of photosensitizer of the present embodiment, indicating that the photosensitizer has strong singlet oxygen production capacity.

[0216] (3) Test of the photodynamic killing ability of fluorescent compounds on MRSA:

[0217] The specific steps are as follows

[0218] Sample preparation: DMSO as solvent, prepare 6.4 mg / mL fluorescent compound stock solution; take appropriate amount of stock solution and dilute with MHB medium to 256 μg / mL as sample solution; the positive control compound is selected as the antibacterial drug vancomycin. Add the sample solution to the 96-well plate and dilute with MHB medium in gradient (128 μg / mL→1 μg / mL). Add MRSA (ATCC43300) bacterial solution, shake and mix for 3 min, and then culture.

[0219] Dark group: tin foil sealed to avoid light, placed in a 37°C incubator for 17 h; light group: tin foil sealed to avoid light, placed in a 37°C incubator for 30 min, then 500-510 nm / 570-590 nm light was used to illuminate the 96-well plate for 30 min, and then placed in the incubator for 16 h.

[0220] The test results are determined by visually observing the colony formation of the 96-well plate and the OD600.

[0221] Table 2

[0222]

[0223]

[0224] Table 2 shows the photodynamic killing of photosensitizer on methicillin-resistant Staphylococcus aureus. From Table 2, it can be seen that the survival rate of methicillin-resistant Staphylococcus aureus in the phototoxicity group decreases significantly, and the survival rate of methicillin-resistant Staphylococcus aureus in the dark toxicity group decreases, but the survival rate is still very high, indicating that the photosensitizer has obvious photodynamic killing effect on methicillin-resistant Staphylococcus aureus, especially the fluorescent compound D28 has very obvious photodynamic killing effect.

[0225] (4) The specific steps of the photodynamic killing ability test on E. coli are as follows:

[0226] DMSO as solvent, compound mother liquor was prepared at 6.4 mg / mL; the sample solution was prepared by diluting the mother liquor with MHB medium to 256 μg / mL; the positive control compound was selected as the antibacterial drug ciprofloxacin. The compound sample solution was added to a 96-well plate, and gradient dilution (128 μg / mL→1 μg / mL) was performed with MHB medium. The E. coli (ATCC25922) bacterial solution was added, and the mixture was shaken for 3 min and then incubated. The dark group was sealed with tin foil to avoid light and incubated in a 37°C incubator for 17 h; the light group was sealed with tin foil to avoid light and incubated in a 37°C incubator for 30 min, then the 96-well plate was irradiated with 500-510 nm / 570-590 nm light for 30 min, and then placed in the incubator for 16 h. The test results were determined by visually observing the colony formation of the 96-well plate and the OD600.

[0227] Table 3

[0228]

[0229]

[0230] As can be seen from Table 3, the survival rate of the E. coli bacteria in the phototoxicity group decreased significantly, and the survival rate of the E. coli bacteria in the dark toxicity group decreased, but the survival rate was still very high, indicating that the photosensitizer has a significant photodynamic killing effect on the E. coli bacteria, especially the fluorescent compound D28, which has a very obvious photodynamic killing effect.

[0231] As can be seen from the line graph in Figure 7 DPBF, the absorption intensity at 412 nm did not change significantly. The DPBF solution added with the compound D28 was oxidized very quickly by the singlet oxygen generated with the extension of the light irradiation time, and the ultraviolet absorption intensity at 412 nm decreased very obviously. The ultraviolet absorption intensity at 412 nm of the DPBF solution added with the commercial RB also decreased, but the decrease was not as obvious as that of the DPBF solution added with the compound D28, proving that the ability of the compound D28 to generate singlet oxygen is much stronger than that of the commercial RB.

[0232] The water-soluble photosensitizer with broad-spectrum antibacterial activity provided by the application has a pyridine salt or a pyridine salt and a quaternary ammonium salt in the molecular structure, wherein the pyridine salt or the quaternary ammonium salt makes the photosensitizer molecule have positive electricity, and the surface of bacteria is negatively charged; due to electrostatic interaction, the photosensitizer synthesized in the application can be effectively combined with bacteria, thereby laying a foundation for subsequent high-efficiency killing; meanwhile, the photosensitizer provided by the application has strong singlet oxygen generation capacity; the photosensitizer synthesized in the application is used for photodynamic antibiosis. In addition, the photosensitizer has good water solubility, which is helpful to improve the biocompatibility and broaden the application range, and can be used to construct photodynamic antibacterial drugs with broad-spectrum antibacterial effect. The application also provides a preparation method of the water-soluble photosensitizer with broad-spectrum antibacterial activity.

[0233] The above description of the embodiments is for facilitating the understanding and use of the application by ordinary skilled in the art. Those skilled in the art can easily make various modifications to the embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the application is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art according to the disclosure of the application without departing from the scope of the application should be within the protection scope of the application.

Claims

1. An electron donor-acceptor type fluorescent compound, characterized in that, The compound has the following structural formula: ； Wherein, R1 is at least one of the following functional groups: ； R2 can be H, -CH3, -COOCH2CH3, -COOCH3, or -NO2; X1 is a halide ion.

2. The electron donor-acceptor dual-fluorescent compound according to claim 1, characterized in that, The compound has the following structural formula: 。 3. A method for preparing an electron donor-acceptor type fluorescent compound as described in claim 1 or 2, characterized in that, The method includes the following steps: ； The compound shown in Formula 2 is mixed with the compound shown in Formula 3 and an organic base, and a brain Wenger reaction is carried out to obtain the electron donor-acceptor type fluorescent compound.

4. The method for preparing the electron donor-acceptor type fluorescent compound according to claim 3, characterized in that, The method for preparing the compound as shown in Formula 2 includes: ； A phenolic compound as shown in Formula 1 and hexamethylenetetramine were mixed and subjected to a synthetic reaction.

5. The method for preparing the electron donor-acceptor type fluorescent compound according to claim 4, characterized in that, The synthesis reaction conditions include at least one of the following: A) The molar ratio of the phenolic compound and hexamethylenetetramine is 1:(2.0~2.5); B) The reaction temperature is 100-120℃, and the reaction time is 20-24 h; C) The reaction solvent is trifluoroacetic acid.

6. The method for preparing the electron donor-acceptor type fluorescent compound according to claim 3, characterized in that, The preparation method of the compound shown in Formula 3 includes: reacting 4-methylpyridine with X1-R1 under heat.

7. The method for preparing the electron donor-acceptor type fluorescent compound according to claim 6, characterized in that, In the heating reaction, the reaction conditions include at least one of the following: A) The molar ratio of the R1 group to 4-methylpyridine in X1-R1 is 1:(1-1.5); B) The reaction temperature is 80-95℃, and the reaction time is 12-24 h; C) The reaction solvent is acetonitrile.

8. The method for preparing the electron donor-acceptor type fluorescent compound according to claim 3, characterized in that, The molar ratio of the compound shown in Formula 2 to the compound shown in Formula 3 is 1:(1.8-2.0); the molar ratio of the compound shown in Formula 2 to the organic base is 1:(2.0-2.5).

9. The method for preparing the electron donor-acceptor type fluorescent compound according to claim 7, characterized in that, In the brain von Willebrand reaction, the reaction temperature is 80-90℃ and the reaction time is 1-3 h.

10. An application of the electron donor-dual acceptor fluorescent compound as described in claim 1 or 2, characterized in that, The electron donor-dual acceptor fluorescent compound is used to prepare antibacterial reagents.

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