A near-infrared emission asymmetric bodipy fluorescent material and a preparation method thereof

Abstract

The application discloses a near-infrared emission asymmetric BODIPY fluorescent material and a preparation method thereof. A near-infrared emission asymmetric BODIPY fluorescent molecule with an electronic push-pull effect and an asymmetric structure is prepared by condensation reaction of a pyrrolopyrrole dione with an aromatic acetonitrile compound and coordination reaction with BF3.Et2O, and has the characteristics of simple synthesis steps, mild conditions, easy structure modification and function regulation, high molar extinction coefficient and large Stokes shift, and has potential application prospects in the fields of fluorescent probes, biological imaging, molecular switches and intelligent sensing.

Description

Technical Field

[0001] This invention belongs to the field of organic small molecule fluorescent materials, and relates to a near-infrared emission asymmetric BODIPY fluorescent material and its preparation method. Background Technology

[0002] BODIPY is a fluorescent dye with excellent photophysical properties. Its core structure consists of two pyrrole rings bridged by a boron atom, forming a stable, rigid planar configuration. BODIPY dyes typically exhibit high fluorescence quantum yield, good photostability, and a narrow emission spectrum, making them promising for applications in fluorescent labeling, bioimaging, cancer therapy (photodynamic and photothermal therapy), materials science, and optoelectronic devices (organic light-emitting diodes (OLEDs), solar cells). For example, BODIPY fluorescent dyes play an important role in biomedical research, particularly in cell imaging and molecular sensing. Due to its good biocompatibility and tunable optical properties, BODIPY is often used to label proteins, nucleic acids, or other biomolecules to visualize dynamic processes within cells. In sensing applications, BODIPY can be used as a fluorescent probe to detect ions or small molecules in the environment; changes in its fluorescence intensity can reflect the concentration of the target analyte.

[0003] The classic synthetic route of BODIPY includes (1) condensation reaction: pyrrole derivatives are condensed with aromatic aldehydes (such as benzaldehyde, p-formylbenzoate, etc.) under acidic conditions (such as trifluoroacetic acid, p-toluenesulfonic acid) to generate dipyrrolemethane intermediate. (2) Oxidative dehydrogenation: dipyrrolemethane is oxidized to dipyrrolemethylene using oxidants (such as DDQ, p-chloroquinone). (3) Boron complexation: dipyrrolemethylene is reacted with boron trifluoride diethyl ether complex (BF3·OEt2) under alkaline conditions to form the BODIPY core structure. The BODIPY core is easily derivatized. By introducing different substituents around its core, near-infrared fluorescent dyes with different excitation and emission wavelengths can be synthesized. The following methods are commonly used: (1) β-position aromatic ring conjugation; (2) Introducing double bonds or other structures at the 3 and 5 positions to extend the conjugation of the core; (3) 2, 3 and 5, 6 positions aromatic ring conjugation; (4) 1, 7, 8 positions aromatic ring conjugation; (5) 2, 6 positions alkynyl group conjugation; (6) meso(7) Replace C atoms with N atoms; replace BF bonds in BODIPY with BC bonds, BN bonds or BO bonds through different reaction pathways. Although the research on near-infrared emitting BODIPY dyes has made great progress, it mainly focuses on the functionalization and derivatization of symmetrical BODIPY molecules. It has shortcomings such as many synthesis steps, harsh reaction conditions, low yield and small Stokes shift (<20 nm), which limit the practical application of this type of dye in different fields. Therefore, it is of great significance to develop a BODIPY fluorescent material with a well-defined structure, simple synthesis and large Stokes shift.

[0004] This invention employs a novel strategy: using asymmetric pyrrolopyrroledione as a raw material, it undergoes a condensation reaction with aromatic acetonitrile compounds and a coordination reaction with BF3·Et2O to prepare near-infrared emitting asymmetric BODIPY fluorescent materials with electronic push-pull effects and asymmetric structures. Through structural optimization using this strategy, its absorption / emission wavelengths are controlled and the Stokes shift is increased. Simultaneously, the dye molecules exhibit a high molar extinction coefficient and excellent photothermal stability, solving the problems of BODIPY dyes having a single structure, limited types of functionalized groups, and difficulty in controlling the emission wavelength. Summary of the Invention

[0005] The purpose of this invention is to provide a near-infrared emission asymmetric BODIPY fluorescent material, the structural formula of which is shown below:

[0006] ,in,

[0007] .

[0008] This material uses BODIPY as its parent core, simultaneously fused with pyrrolopyrrolidone and aromatic group units and in... meso By introducing cyano groups at specific positions, a near-infrared emission asymmetric BODIPY fluorescent material was constructed.

[0009] The preparation process of near-infrared emission asymmetric BODIPY fluorescent materials is as follows:

[0010]

[0011] Its preparation method includes the following steps:

[0012] (1) Mix o-methoxybenzaldehyde and 1-3 times the amount of n-butylamine, add an alcohol solvent, and react at room temperature for 10-60 min. Then add 1-3 times the amount of sodium diethyl oxaloacetate and 2-3 times the amount of acetic acid, and react at 30-70°C. oThe reaction was carried out at C for 6-24 h. After the reaction was completed, the mixture was cooled to room temperature, extracted with dichloromethane, the organic layers were combined, dried with anhydrous sodium sulfate, and distilled under reduced pressure to obtain the crude product. The crude product was recrystallized to obtain intermediate 1.

[0013] (2) After mixing intermediate 1 with 2 to 7 times the amount of reducing agent, add a mixed solvent of ethanol and acetic acid, heat to 40 to 100 °C for 1 to 3 h, cool to room temperature after the reaction, extract with dichloromethane, combine the organic layers, dry with anhydrous sodium sulfate, and distill under reduced pressure to obtain intermediate 2.

[0014] (3) Dissolve intermediate 2 and 1-3 times the amount of triethylamine in dichloromethane and mix evenly. Then slowly add 1-3 times the amount of trimethylchlorosilane and react at 20-60 °C for 1-4 h. After the reaction is completed, cool to room temperature, extract with dichloromethane, combine the organic layers, dry with anhydrous sodium sulfate, and distill under reduced pressure to obtain intermediate 3.

[0015] (4) After mixing 3, 4 to 5 times the amount of intermediate lithium tert-butoxide, 1 to 3 times the amount of aromatic cyano compound and tert-amyl alcohol evenly, heat to 50 to 110 °C for 3 to 15 h under argon protection. After the reaction is completed, cool to room temperature, extract with dichloromethane, combine the organic layers, dry with anhydrous sodium sulfate, and distill under reduced pressure to obtain crude product. The crude product is recrystallized to obtain intermediate 4.

[0016] (5) After mixing 4 to 6 times the amount of intermediate phosphorus oxychloride, 1 to 3 times the amount of aromatic acetonitrile compound and high-boiling solvent evenly, the mixture was reacted at 60-115 °C for 1 to 3 h. After the reaction was completed, the mixture was cooled to room temperature and 1 to 3 times the amount of N,N-diisopropylethylamine and 1 to 3 times the amount of BF3.Et2O were added. The mixture was reacted at 25-45 °C for 1 to 5 h. After the reaction was completed, the mixture was cooled to room temperature and the crude product was obtained by vacuum distillation. The crude product was purified by column chromatography to obtain near-infrared emission asymmetric BODIPY fluorescent material.

[0017] Preferably, the alcohol solvent in step (1) is selected from one of methanol, ethanol, n-propanol, isopropanol, n-butanol, n-pentanol, and n-hexanol.

[0018] More preferably, the alcohol solvent in step (1) is ethanol.

[0019] Preferably, the reducing agent in step (2) is selected from one of NaBH4, zinc powder, Pd / C, and LiAlH4.

[0020] More preferably, the reducing agent in step (2) is zinc powder.

[0021] The high-boiling-point solvent mentioned in step (5) is selected from one of toluene, chlorobenzene, dioxane, o-dichlorobenzene, dimethylformamide, xylene, and dimethyl sulfoxide.

[0022] More preferably, the high-boiling-point solvent in step (2) is dioxane.

[0023] As can be seen from the above technical solution, compared with the prior art, the present invention provides a near-infrared emission asymmetric BODIPY fluorescent material and its preparation method, which has the following beneficial effects:

[0024] 1. Unlike the classic BODIPY synthesis method, this invention adopts a new synthesis strategy: using pyrrolopyrrole dione with an asymmetric structure as a raw material, it undergoes a condensation reaction with aromatic acetonitrile compounds and a coordination reaction with BF3·Et2O to prepare near-infrared emitting asymmetric BODIPY fluorescent materials with electronic push-pull effect and asymmetric structure.

[0025] 2. The obtained material has the characteristics of high molar extinction coefficient and large Stokes displacement.

[0026] 3. This type of asymmetric BODIPY fluorescent material is easy to modify in structure and modulate in function, providing an ideal platform for subsequent functional expansion.

[0027] 4. The preparation method provided by this invention has simple steps and mild conditions. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 BODIPY-A prepared in Example 1 1 H-NMR spectrum.

[0030] Figure 2 BODIPY-B prepared in Example 2 1 H-NMR spectrum.

[0031] Figure 3 The BODIPY-C prepared in Example 3 1 H-NMR spectrum.

[0032] Figure 4 BODIPY-D prepared in Example 4 1 H-NMR spectrum.

[0033] Figure 5 The UV absorption spectrum of BODIPY-A prepared in Example 1, with a concentration of 1*10⁻⁶. -6 mol / L, solvent is 1,4-dioxane.

[0034] Figure 6 The UV absorption spectrum of BODIPY-B prepared in Example 2, with a concentration of 1*10⁻⁶. -6 mol / L, solvent is 1,4-dioxane.

[0035] Figure 7 The UV absorption spectrum of BODIPY-C prepared in Example 3, with a concentration of 1*10⁻⁶. -6 mol / L, solvent is 1,4-dioxane.

[0036] Figure 8 The UV absorption spectrum of BODIPY-D prepared in Example 4, with a concentration of 1*10⁻⁶. -6 mol / L, solvent is 1,4-dioxane.

[0037] Figure 9 The fluorescence spectrum of BODIPY-A prepared in Example 1, with a concentration of 1*10⁻⁶. -6 mol / L, solvent is 1,4-dioxane.

[0038] Figure 10 The fluorescence spectrum of BODIPY-B prepared in Example 2, with a concentration of 1*10⁻⁶. -6 mol / L, solvent is 1,4-dioxane.

[0039] Figure 11 The fluorescence spectrum of BODIPY-C prepared in Example 3, with a concentration of 1*10⁻⁶. -6 mol / L, solvent is 1,4-dioxane.

[0040] Figure 12 The fluorescence spectrum of BODIPY-D prepared in Example 4, with a concentration of 1*10⁻⁶. -6 mol / L, solvent is 1,4-dioxane. Detailed Implementation

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] A method for preparing near-infrared emission asymmetric BODIPY fluorescent materials includes the following steps:

[0044] 2-(5-(tert-butyl)[d]azole-2-acetonitrile was prepared according to the literature.

[0045] Synthesis of Intermediate 1

[0046]

[0047] o-Methoxybenzaldehyde (2.72 g, 20 mmol), n-butylamine (1.46 g, 20 mmol), and 60 mL of ethanol were added to a 250 mL round-bottom flask and reacted at room temperature for 20 minutes. Then, sodium diethyl oxaloacetate (4.20 g, 20 mmol) and acetic acid (2.40 g, 40 mmol) were added, and the mixture was reacted at 40 °C. o The reaction was carried out at C for 24 hours. After the reaction was completed, the mixture was cooled to room temperature and extracted three times with dichloromethane and water. The organic layers were combined, dried with anhydrous sodium sulfate, and distilled under reduced pressure to obtain the crude product. The crude product was recrystallized (ethyl acetate as a good solvent and petroleum ether as a poor solvent) to give 4.66 g of white solid product (intermediate 1), with a yield of 70%. 1 H NMR (500 MHz, CDCl3) δ 9.15 (brs, 1H), 7.37 – 7.22 (m, 1H), 7.06 –6.66 (m, 2H), 5.86 (brs, 1H), 5.18 (brs, 1H), 4.11 (qd, J = 7.1, 3.3 Hz, 2H), 3.90 (brs, 3H), 3.72 (dt, J = 13.8, 7.4 Hz, 1H), 2.64 (m, 1H), 1.53 – 1.39 (m, 2H), 1.25-1.08 (m, 5H), 0.86 (t, J = 7.4 Hz, 3H).

[0048] Synthesis of intermediate 2

[0049]

[0050] Weigh intermediate 1 (3.33 g, 10 mmol) and zinc powder (3.84 g, 60 mmol) into a 100 mL round-bottom flask. Add 10 mL of ethanol and 10 mL of acetic acid to the flask and heat to 95°C. oThe reaction was carried out at C for 2 hours. After the reaction was completed, the mixture was cooled to room temperature and extracted three times with dichloromethane. The organic layers were combined, dried over anhydrous sodium sulfate, and distilled under reduced pressure to give 3.02 g of white solid product (intermediate 2), with a yield of 90%. 1 H NMR (500 MHz, DMSO- d 6) δ 7.34 (td, J = 8.3, 7.6,1.7 Hz, 1H), 7.18 (dd, J = 7.6, 1.7 Hz, 1H), 7.06 (d, J = 8.3 Hz, 1H), 7.01 (t, J = 7.6 Hz, 1H), 6.04 (d, J = 6.7 Hz, 1H), 4.95 (brs, 1H), 4.35 (dd, J =8.1, 6.7 Hz, 1H), 4.14 – 4.00 (m, 2H), 3.77 (s, 3H), 3.48 (dt, J = 8.3, 7.6Hz, 1H), 2.84 (brs, 1H), 2.42-2.40 (m, 1H), 1.24 – 1.13 (m, 4H), 1.10 (t, J =7.1 Hz, 3H), 0.77 (t, J = 7.3 Hz, 3H).

[0051] Synthesis of intermediate 3

[0052]

[0053] Intermediate 2 (3.35 g, 10 mmol), triethylamine (2.03 g, 20 mmol), and 60 mL of ultra-dry dichloromethane were weighed and added to a 250 mL reaction flask. Then, trimethylchlorosilane (2.18 g, 20 mmol) was added dropwise, and the mixture was reacted at room temperature for 2 hours. After the reaction was completed, the mixture was extracted three times with dichloromethane, and the organic layers were combined, dried over anhydrous sodium sulfate, and distilled under reduced pressure to give 3.71 g of yellow oily product (intermediate 3), with a yield of 90%. 1 H NMR (500 MHz, CDCl3) δ 7.36 – 7.26 (m, 1H), 7.21 – 7.15 (m, 1H), 6.97 (q, J = 7.6, 7.0 Hz, 1H), 6.90 (t, J= 8.8 Hz, 1H), 5.09 (brs, 2H), 4.59 (d, J = 7.6 Hz, 1H), 4.15 (q, J = 7.1 Hz, 2H), 3.80 (s, 3H), 3.64 (dq, J = 7.4, 7.8 Hz, 1H), 2.51 (dt, J = 6.8, 7.1 Hz, 1H), 1.34 (dt, J = 7.8, 7.1 Hz, 2H), 1.20 (t, J = 7.1 Hz, 3H), 1.18 – 1.12 (m, 2H), 0.81 (t, J = 7.3 Hz, 3H), 0.19 (s, 9H).

[0054] Synthesis of intermediate 4A

[0055]

[0056] Lithium tert-butoxide (3.20 g, 40 mmol) was weighed and added to a 100 mL round-bottom flask. The flask was purged with argon three times. Then, intermediate 3 (4.07 g, 10 mmol), 2-cyanothiophene (1.65 g, 15 mmol), and 20 mL of tert-amyl alcohol were added and heated to 110°C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature and extracted three times with dichloromethane. The organic layers were combined, dried over anhydrous sodium sulfate, and distilled under reduced pressure to obtain the crude product. The crude product was recrystallized (ethyl acetate as a good solvent and petroleum ether as a poor solvent) to give 2.28 g of red solid product (intermediate 4A), with a yield of 60%. 1 H NMR (400 MHz, CDCl3) δ 9.30 (s,1H), 8.26 (d, J = 3.9 Hz, 1H), 7.59 (dd, J = 5.0, 1.0 Hz, 1H), 7.53 (dd, J =7.6, 5.8 Hz, 1H), 7.48 (dd, J = 8.2, 6.8 Hz, 1H), 7.18 (dd, J = 5.0, 3.9 Hz,1H), 7.10 (td, J = 7.6, 5.0 Hz, 1H), 7.02 (d, J= 8.2 Hz, 1H), 3.86 (s, 3H), 3.72 – 3.51 (m, 2H), 1.48-1.45 (m, 2H), 1.16-1.13 (m, 2H), 0.76 (t, J = 7.4Hz, 3H).

[0057] Synthesis of BODIPY-A

[0058]

[0059] Intermediate 4A (0.19 g, 0.5 mmol) was added to a 50 mL two-necked flask, and the flask was purged with argon three times. Then, phosphorus oxychloride (0.38 g, 2.5 mmol), 2-(5-(tert-butyl)[d]azole-2-acetonitrile (0.22 g, 1.0 mmol), and 1,4-dioxane (10 mL) were added. The reaction was carried out at 110 °C for 2 h. After the reaction was complete, the mixture was cooled to room temperature, and N,N-diisopropylethylamine (0.13 g, 1.0 mmol) and boron trifluoride diethyl ether (0.15 g, 1.0 mmol) were added. The reaction was carried out at 40 °C for 4 h. The crude product was obtained by vacuum distillation and purified by column chromatography (ethyl acetate: petroleum ether = 1:4, v / v) to give 0.08 g of purple solid (BODIPY-A), with a yield of 25%. 1 H NMR (500 MHz, CDCl3) δ 8.54 (d, J = 3.9 Hz, 1H), 7.64 –7.50 (m, 3H), 7.34 – 7.28 (m, 3H), 7.17 – 7.01 (m, 3H), 3.83 (s, 3H), 3.47 (ddd, J = 15.4, 8.4, 6.0 Hz, 2H), 1.38 (q, J = 7.3 Hz, 2H), 1.29 (s, 9H), 1.10 (q, J = 7.4 Hz, 2H), 0.69 (t, J = 7.4 Hz, 3H).

[0060] Example 2

[0061] Synthesis of intermediate 4B

[0062]

[0063] Lithium tert-butoxide (3.20 g, 40 mmol) was weighed and added to a 100 mL round-bottom flask. The flask was purged with argon three times. Then, intermediate 3 (4.07 g, 10 mmol), 3,5-bis(trifluoromethyl)benzonitrile (3.60 g, 15 mmol), and 20 mL of tert-amyl alcohol were added. The mixture was heated to 110 °C and reacted for 12 hours. After the reaction was complete, the mixture was cooled to room temperature and extracted three times with dichloromethane and water. The organic layers were combined, dried over anhydrous sodium sulfate, and distilled under reduced pressure to obtain the crude product. The crude product was recrystallized (ethyl acetate as a good solvent, petroleum ether as a poor solvent) to give 2.30 g of a red solid product (intermediate 4B), with a yield of 45%. 1 H NMR (500 MHz, CDCl3) δ 11.61 (s, 1H), 8.86 (s, 2H), 7.81 (s, 1H), 7.48 – 6.97 (m, 4H), 3.78 (s, 3H), 3.55 (s, 2H), 1.42 – 1.30 (m, 2H), 1.16 - 1.05 (m, 2H), 0.66 (s, 3H).

[0064] Synthesis of BODIPY-B

[0065]

[0066] Intermediate 4B (0.26 g, 0.5 mmol) was added to a 50 mL two-necked flask, and the flask was purged with argon three times. Then, phosphorus oxychloride (0.38 g, 2.5 mmol), 2-(5-(tert-butyl)[d]azole-2-acetonitrile (0.22 g, 1.0 mmol), and 1,4-dioxane (10 mL) were added. The mixture was reacted at 110 °C for 2 h. After the reaction was complete, the mixture was cooled to room temperature, and N,N-diisopropylethylamine (0.13 g, 1.0 mmol) and boron trifluoride diethyl ether (0.15 g, 1.0 mmol) were added. The mixture was reacted at 40 °C for 4 h. The crude product was obtained by vacuum distillation and purified by column chromatography (ethyl acetate: petroleum ether = 1:4, v / v) to give 0.08 g of purple solid BODIPY-B, with a yield of 20%. 1 H NMR (500 MHz, CDCl3) δ 8.51 (s, 2H), 7.95 (s, 1H), 7.57 –7.55 (m, 1H), 7.37 – 7.30 (m, 3H), 7.19 – 7.06 (m, 3H), 3.87 (s, 3H), 3.52 –3.41 (m, 2H), 1.41 – 1.32 (m, 2H), 1.28 (s, 9H), 1.09 (q,J = 7.4 Hz, 2H), 0.68 (t, J = 7.3 Hz, 3H).

[0067] Example 3

[0068] Synthesis of BODIPY-C

[0069]

[0070] Intermediate 4A (0.19 g, 0.5 mmol) was added to a 50 mL two-necked flask, and the flask was purged with argon three times. Then, phosphorus oxychloride (0.38 g, 2.5 mmol), 2-(1H-benzo[d]imidazol-2-yl)acetonitrile (0.16 g, 1.0 mmol), and 1,4-dioxane (10 mL) were added. The reaction was carried out at 110 °C for 2 h. After the reaction was complete, the mixture was cooled to room temperature, and N,N-diisopropylethylamine (0.13 g, 1.0 mmol) and boron trifluoride diethyl ether (0.15 g, 1.0 mmol) were added. The reaction was carried out at 40 °C for 4 h. The crude product was obtained by vacuum distillation and purified by column chromatography (ethyl acetate: petroleum ether = 1:4, v / v) to give 0.07 g of purple solid BODIPY-C, with a yield of 25%. 1 H NMR (500 MHz, CDCl3) δ 10.36 (s, 1H), 8.64 (s, 1H), 7.78 (d, J = 6.0 Hz, 1H), 7.62 (d, J = 5.0 Hz, 1H), 7.26 (t, J = 6.0 Hz, 1H), 7.21– 7.13 (m, 3H), 7.06 (t, J = 8.0 Hz, 1H), 6.92 (t, J = 7.0 Hz, 1H), 6.80 (t, J = 7.0 Hz, 1H), 3.76 (s, 3H), 3.43 (t, J = 8.0 Hz, 2H), 1.40 – 1.27 (m, 2H), 1.10 – 1.03 (m, 2H), 0.67 (t, J = 7.5 Hz, 3H).

[0071] Example 4

[0072] Synthesis of BODIPY-D

[0073]

[0074] Intermediate 4B (0.26 g, 0.5 mmol) was added to a 50 mL two-necked flask, and the flask was purged with argon three times. Then, phosphorus oxychloride (0.38 g, 2.5 mmol), 2-(1H-benzo[d]imidazol-2-yl)acetonitrile (0.16 g, 1.0 mmol), and 1,4-dioxane (10 mL) were added. The reaction was carried out at 110 °C for 2 h. After the reaction was complete, the mixture was cooled to room temperature, and N,N-diisopropylethylamine (0.13 g, 1.0 mmol) and boron trifluoride diethyl ether (0.15 g, 1.0 mmol) were added. The reaction was carried out at 40 °C for 4 h. The crude product was obtained by vacuum distillation and purified by column chromatography (ethyl acetate: petroleum ether = 1:4, v / v) to give 0.05 g of purple solid BODIPY-D, with a yield of 15%. 1 H NMR (500 MHz, CDCl3) δ 10.67 (s, 1H), 8.59 (s, 2H), 7.93 (s, 1H), 7.68 (d, J = 7.0 Hz, 1H), 7.46 (d, J = 5.0 Hz, 1H), 7.37 – 7.26 (m, 3H), 7.08 – 6.89 (m, 3H), 3.83 (s, 3H), 3.43 (t, J = 8.0 Hz, 2H), 1.40 – 1.27 (m, 2H), 1.10 – 1.03 (m, 2H), 0.66 (t, J = 7.5 Hz, 3H).

[0075] Performance testing

[0076] Four asymmetric BODIPY fluorescent materials were dissolved in 1,4-dioxane to prepare a concentration of 1*10⁻⁶. -6The maximum absorption and emission peaks of BODIPY-A were 570 nm and 605 nm, respectively. Replacing the electron-donating thiophene group with an electron-withdrawing 3,5-trifluoromethylphenyl group caused a red shift in both the maximum absorption and emission peaks of BODIPY-B, placing them at 580 nm and 625 nm, respectively. Similar trends were observed in BODIPY-C and BODIPY-D, with maximum absorption and emission peaks at 575 / 595 nm and 605 / 630 nm, respectively, indicating stronger intramolecular charge transfer characteristics in BODIPY-B and BODIPY-D molecules, leading to the spectral red shift. The Stokes shifts of the four compounds were between 35 and 45 nm, greater than the Stokes shift of the common symmetrical structure BODIPY (< 20 nm). The molar extinction coefficients of the four compounds ranged from 23,000 to 55,000 MΩ. - 1 cm -1 The data is shown in Table 1.

[0077] Table 1. Summary of photophysical properties of four asymmetric BODIPY fluorescent materials

[0078] compound Maximum absorption wavelength (nm) Maximum emission wavelength (nm) Stokes displacement (nm) <![CDATA[Molar extinction coefficient (M -1 cm -1 ).]]> BODIPY-A 570 605 35 55000 BODIPY-B 580 625 45 40000 BODIPY-C 575 610 35 38000 BODIPY-D 590 630 40 23000

[0079] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A near-infrared emission asymmetric BODIPY fluorescent material, characterized in that, The structural formula is: ， 。 2. The method for preparing the near-infrared emission asymmetric BODIPY fluorescent material according to claim 1, characterized in that, The process is as follows: ， 。 3. The method for preparing near-infrared emission asymmetric BODIPY fluorescent material according to claim 2, characterized in that, Includes the following steps: (1) mixing o-methoxybenzaldehyde and 1-3 times the amount of n-butylamine, adding an alcohol solvent, reacting at room temperature for 10-60 min, then adding 1-3 times the amount of sodium salt of oxalyl diethyl ester and 2-3 times the amount of acetic acid, reacting at 30-70 o C for 6-24 h, cooling to room temperature after the reaction is completed, extracting with dichloromethane, drying the combined organic layers with anhydrous sodium sulfate, distilling the crude product under reduced pressure, and recrystallizing the crude product to obtain intermediate 1; (2) After mixing intermediate 1 with 2 to 7 times the amount of reducing agent, add a mixed solvent of ethanol and acetic acid, heat to 40 to 100 °C for 1 to 3 h, cool to room temperature after the reaction is completed, extract with dichloromethane, combine the organic layers, dry with anhydrous sodium sulfate, and distill under reduced pressure to obtain intermediate 2. (3) Dissolve intermediate 2 and 1-3 times the amount of triethylamine in dichloromethane and mix evenly. Then slowly add 1-3 times the amount of trimethylchlorosilane and react at 20-60 °C for 1-4 h. After the reaction is completed, cool to room temperature, extract with dichloromethane, combine the organic layers, dry with anhydrous sodium sulfate, and distill under reduced pressure to obtain intermediate 3. (4) Mix 3, 4 to 5 times the amount of lithium tert-butoxide, 1 to 3 times the amount of Ar1-CN compound and tert-amyl alcohol evenly, and heat to 50 to 110 °C for 3 to 15 h under argon protection. After the reaction is completed, cool to room temperature, extract with dichloromethane, combine the organic layers, dry with anhydrous sodium sulfate, and distill under reduced pressure to obtain crude product. The crude product is recrystallized to obtain intermediate 4. (5) Add 4 to 6 times the amount of phosphorus oxychloride and 1 to 3 times the amount of phosphorus oxychloride to the intermediate. After the compound and a high-boiling-point solvent are mixed evenly, the reaction is carried out at 60-115 °C for 1-3 h. After the reaction is completed, the mixture is cooled to room temperature, and 1-3 times the amount of N,N-diisopropylethylamine and 1-3 times the amount of BF3·Et2O are added. The mixture is then reacted at 25-45 °C for 1-5 h. After the reaction is completed, the mixture is cooled to room temperature, and the crude product is obtained by vacuum distillation. The crude product is purified by column chromatography to obtain a near-infrared emitting asymmetric BODIPY fluorescent material. The high-boiling-point solvent is selected from toluene, chlorobenzene, dioxane, o-dichlorobenzene, dimethylformamide, xylene, and dimethyl sulfoxide.

4. The method for preparing near-infrared emission asymmetric BODIPY fluorescent material according to claim 3, wherein the alcohol solvent in step (1) is selected from one of methanol, ethanol, n-propanol, isopropanol, n-butanol, n-pentanol, and n-hexanol.

5. The method for preparing near-infrared emission asymmetric BODIPY fluorescent material according to claim 3, wherein the reducing agent in step (2) is selected from one of NaBH4, zinc powder, Pd / C, and LiAlH4.

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