Aggregation-induced emission materials with multi-photon absorption properties, and preparation method and application thereof

Abstract

The application discloses a preparation method and application of an aggregation-induced emission material with multi-photon absorption properties, and a structural formula of the aggregation-induced emission material is shown as formula I or formula II: wherein R1 and R2 are each independently represented as: the application constructs a series of aggregation-induced emission molecules based on a pyrazine [2,3-g] quinoxaline structural unit, the molecules have strong intramolecular charge transfer characteristics, triphenylamine as an electron donor has a large absorption cross section, so that the material has the multi-photon absorption properties. The molecules have strong absorption and high quantum yield in the wavelength range of 400-700 nm, and show good photodynamic activity. The molecules have the characteristics of simple structure, easy modification, adjustable performance and easy preparation, and have good application prospects in the aspect of multi-photon fluorescence imaging.

Description

Technical Field

[0001] This invention belongs to the field of aggregation-induced emission materials technology, specifically relating to a method for preparing and applying an aggregation-induced emission material with multiphoton absorption properties. Background Technology

[0002] Aggregation-induced emission (AIE) molecules possess excellent resistance to photobleaching, biocompatibility, and high emission intensity, fundamentally solving the aggregation-induced quenching (ACQ) problem inherent in traditional organic fluorescent molecules. The rise of AIE fluorescent materials has provided new options for analytical detection, bioimaging, and other fields. In particular, AIE fluorescent materials with multiphoton absorption properties offer fascinating and challenging identification of specific bioactive analytes.

[0003] Multiphoton imaging technology has achieved remarkable results in the biomedical field due to its advantages such as high spatial resolution, high penetration depth, low invasiveness, and inherent optical tomography capabilities.

[0004] Currently, although many high-performance aggregation-induced emission materials have been screened out, their structures are often complex and difficult to synthesize on a large scale, making it difficult to meet the requirements for later-stage and clinical trials.

[0005] Therefore, continuing to explore and screen novel aggregation-induced emission materials that possess both high absorption cross-section and high fluorescence quantum yield, while also having simple synthesis methods and relatively low cost, has very important theoretical and practical significance. Summary of the Invention

[0006] The first objective of this invention is to provide a series of aggregation-induced emission materials with multiphoton absorption properties. These compounds, based on pyrazine[2,3-g]quinoxaline structural units, have advantages such as simple structure, easy modification, tunable performance, easy preparation, and very high quantum yield under illumination.

[0007] A second objective of this invention is to provide a method for preparing the above-mentioned compound.

[0008] A third object of the present invention is to provide the application of the above-mentioned compounds in fluorescence imaging.

[0009] To achieve the first objective, the present invention adopts the following technical solution:

[0010] An aggregation-induced emission material with multiphoton absorption properties, wherein the structural formula of the aggregation-induced emission material is shown in Formula I or Formula II:

[0011]

[0012] Formula I Formula II

[0013] Where R1 and R2 are represented independently as follows:

[0014] , , , , or .

[0015] In this invention, aggregation-induced emission molecules with multiphoton absorption properties are constructed based on the pyrazine [2, 3-g]quinoxaline structural unit. These molecules exhibit strong intramolecular charge transfer characteristics. Triphenylamine, as an electron donor, has a large absorption cross-section, thus endowing the material with multiphoton absorption properties. Here, "[2, 3-g]" indicates the connection mode between the quinoxaline ring and the pyrazine ring, that is, the 2-position of quinoxaline is connected to the 3-position of pyrazine, forming a bridging structure.

[0016] As a preferred technical solution, in the aggregation-induced emission material, R1 and R2 are each independently represented as follows:

[0017] .

[0018] Secondly, a method for preparing the compound represented by Formula I in the first aspect, wherein R1 is... R2 is The preparation method includes the following steps:

[0019] The second intermediate was mixed with ethanol and dichloromethane, and glyoxal was added under stirring. The mixture was then refluxed in an inert gas atmosphere to obtain a reaction mixture. The structural formula of the second intermediate is as follows:

[0020] ;

[0021] The acetic acid in the reaction mixture is neutralized, and then extracted with an extractant to obtain an organic phase;

[0022] Removing the solvent from the organic phase yields compound PQ-L1; the structural formula of compound PQ-L1 is:

[0023] .

[0024] As a preferred technical solution, the preparation method, wherein the preparation method of the second intermediate includes:

[0025] The first intermediate, 1,2,4,5-phenyltetramine tetrahydrochloride, and potassium carbonate aqueous solution were dispersed in ethanol and stirred at 75-95°C under inert gas protection to obtain the second intermediate; the structural formula of the first intermediate is as follows. .

[0026] As a preferred technical solution, in the preparation method, the molar ratio of the first intermediate, 1,2,4,5-phenyltetramine tetrahydrochloride and potassium carbonate is 4:3-4:7.2.

[0027] As a preferred technical solution, the preparation method, wherein the preparation method of the first intermediate includes:

[0028] Under inert gas protection, triphenylamine was dissolved in anhydrous dichloromethane, and anhydrous aluminum chloride was added and stirred to obtain a reaction solution;

[0029] The reaction solution temperature was maintained at 0°C, and oxalyl chloride was added dropwise to the reaction solution to obtain the first intermediate.

[0030] As a preferred technical solution, in the preparation method, the molar ratio of triphenylamine, anhydrous aluminum chloride and oxalyl chloride is 2-3:1:1.

[0031] A third party, a method for preparing the compound represented by Formula I in the first aspect, wherein R1 and R2 are both... The preparation method includes the following steps:

[0032] The first intermediate, 1,2,4,5-phenyltetramine tetrahydrochloride, was dispersed in a mixed solution of toluene and pyridine and stirred under inert gas protection at 20°C to obtain compound PQ-L3.

[0033] The structural formula of the first intermediate is ;

[0034] The structural formula of the compound PQ-L3 is as follows:

[0035] .

[0036] Fourthly, a method for preparing the compound represented by Formula II above, wherein R1 is... The preparation method includes the following steps:

[0037] The third intermediate and N 1-Brominated succinimide was dispersed in a mixed solution of dimethylformamide and acetic acid, and the reaction mixture was stirred under inert gas protection at 50-70°C.

[0038] The solvent in the reaction mixture was removed, the residue was dissolved in toluene, and 4-boronic acid triphenylamine, tetra(triphenylphosphine)palladium and potassium carbonate aqueous solution were added. The mixture was stirred under inert gas protection at 110-130°C to obtain compound PQ-L2.

[0039] The structural formula of the third intermediate is:

[0040] ;

[0041] The structural formula of PQ-L2 is:

[0042] .

[0043] Fourthly, the application of the aggregation-induced emission material with multiphoton absorption properties described in the first aspect in multiphoton fluorescence imaging.

[0044] Beneficial effects: Compared with existing technologies, this invention presents aggregation-induced emission molecules with multiphoton absorption properties constructed based on pyrazine[2,3-g]quinoxaline structural units. These molecules exhibit strong intramolecular charge transfer characteristics. Triphenylamine, as an electron donor, has a large absorption cross-section, thus endowing the material with multiphoton absorption properties. These molecules exhibit strong absorption and high quantum yield in the 400-700 nm wavelength range and demonstrate good photodynamic activity. These molecules are characterized by simple structure, easy modification, tunable performance, and ease of preparation, showing promising application prospects in multiphoton fluorescence imaging.

[0045] Based on the same inventive concept, the present invention provides a method for preparing the compound shown in Formula I, comprising the following steps:

[0046]

[0047] Specifically, (1) the synthesis of intermediate 1: under nitrogen protection at 0°C, triphenylamine was dissolved in anhydrous dichloromethane, and anhydrous aluminum chloride was added and the solution was stirred. Oxaloyl chloride was added dropwise while maintaining the temperature of the reaction system at 0°C, and the mixture was stirred at room temperature for 6 h. The molar ratio of triphenylamine, anhydrous aluminum chloride and oxaloyl chloride was 3:1:1, and the dichloromethane was 200 ml.

[0048] (2) Synthesis of intermediate 2: At room temperature, intermediate 1, 1,2,4,5-phenyltetramine tetrahydrochloride and potassium carbonate aqueous solution were added to ethanol and stirred for 12 h under nitrogen protection at 85 °C. The molar ratio of intermediate 1, 1,2,4,5-phenyltetramine tetrahydrochloride and potassium carbonate was 4:3.7:7.2, and the mixture contained 100 ml of ethanol and 5 ml of water.

[0049] (3) Synthesis of compound PQ-L1: At room temperature, intermediate 2 was added to acetic acid and dichloromethane, and glyoxal was added to the solution under stirring. The reaction mixture was stirred under reflux for 6 h under nitrogen protection. The molar ratio of intermediate 2 to glyoxal was 1:2, and the mixture contained acetic acid (20 ml) and dichloromethane (10 ml).

[0050] (4) Synthesis of compound PQ-L3: At room temperature, intermediate 1 and 1,2,4,5-phenyltetramine tetrahydrochloride were added to a freshly distilled toluene and pyridine solution, and the mixture was stirred for 48 h under nitrogen protection at 20 °C. The molar ratio of intermediate 1 to 1,2,4,5-phenyltetramine tetrahydrochloride was 2-4:1, with toluene (25 ml) and pyridine (10 ml).

[0051] (5) Synthesis of compound PQ-L4: At room temperature, compound PQ-L3 and... N 1-Bromosuccinimide was added dropwise to a stirred solution with acetic acid. The reaction mixture was stirred at room temperature for 0.5–2 h. After removing the solvent, the residue was dissolved in freshly distilled toluene, and 4-boronic acid triphenylamine, tetra(triphenylphosphine)palladium, and potassium carbonate aqueous solution were added. The mixture was stirred at 120 °C under nitrogen protection for 24 h. Compound PQ-L3 was involved. N The molar ratio of 1:1.01:2.5:0.1:4 for 1-bromosuccinimide, 4-boronic acid triphenylamine, tetra(triphenylphosphine)palladium and potassium carbonate is 25 ml, 3-5 drops of acetic acid, 30 ml of toluene, and 1 ml of water.

[0052] Furthermore, the present invention also provides a method for preparing the compound shown in Formula II, comprising the following steps:

[0053]

[0054] Specifically, (6) the synthesis of intermediate 3: at room temperature, 1,2,4,5-phenyltetramine tetrahydrochloride, sodium acetate and glyoxal were added to an ethanol solution and stirred under nitrogen protection for 0.5-1 h. The molar ratio of 1,2,4,5-phenyltetramine tetrahydrochloride, sodium acetate and glyoxal was 1:4:3, and the mixture contained 50 ml of ethanol and 5 ml of water.

[0055] (7) Synthesis of compound PQ-L2: At room temperature, intermediate 3 and... N 3-Bromosuccinimide was reacted with the reaction mixture at 60°C under nitrogen protection for 16 h. The solvent was removed, and the residue was dissolved in freshly distilled toluene. Triphenylamine 4-borate, tetrakis(triphenylphosphine)palladium, and an aqueous solution of potassium carbonate were added, and the mixture was stirred at 120°C under nitrogen protection for 24 h. Intermediate 3... N The molar ratio of 1:2.02:2.5:0.1:4 for 1-bromosuccinimide, 2-boronic acid triphenylamine, tetra(triphenylphosphine)palladium and potassium carbonate, dimethylformamide (25 ml), 3-5 drops of acetic acid, toluene (30 ml), and water (1 ml) are added.

[0056] In this invention, compared with two-photon microscopy, three-photon microscopy has the following advantages: (1) The three-photon excitation wavelength of commonly used fluorescent proteins is longer, usually 1600-1800 nm, which is in the optimal infrared light transmission window of biological tissues, resulting in better penetration in biological tissues; (2) As a higher-order nonlinear imaging method, three-photon microscopy not only has the optical sectioning capability of two-photon microscopy, but also has a better ability to suppress background signals than two-photon microscopy. Four-photon microscopy has the following advantages: (1) Four-photon fluorescence imaging can achieve deeper tissue imaging because the laser wavelength used is longer, resulting in stronger tissue penetration; (2) Four-photon imaging technology has higher spatial resolution; (3) Due to the lower laser power used, four-photon imaging causes less damage to tissues and is suitable for long-term live cell imaging. Attached Figure Description

[0057] Figure 1 This is the 1H NMR spectrum of the first intermediate molecule prepared in Example 1 of the present invention in deuterated dimethyl sulfoxide;

[0058] Figure 2 This is the 1H NMR spectrum of the second intermediate molecule prepared in Example 2 of this invention in deuterated dichloromethane;

[0059] Figure 3 This is the 1H NMR spectrum of compound PQ-L1 molecule prepared in deuterated dichloromethane in Example 3 of this invention;

[0060] Figure 4 This is the carbon NMR spectrum of compound PQ-L1 molecule prepared in Example 3 of this invention in deuterated dichloromethane;

[0061] Figure 5 This is the 1H NMR spectrum of compound PQ-L3 molecule prepared in deuterated dichloromethane in Example 4 of this invention;

[0062] Figure 6 This is the carbon NMR spectrum of compound PQ-L3 molecule prepared in Example 4 of this invention in deuterated dichloromethane;

[0063] Figure 7 This is the 1H NMR spectrum of compound PQ-L4 molecule prepared in deuterated dichloromethane in Example 5 of this invention;

[0064] Figure 8 This is the carbon NMR spectrum of compound PQ-L4 molecule prepared in Example 5 of this invention in deuterated dichloromethane;

[0065] Figure 9 This is the 1H NMR spectrum of the third intermediate molecule prepared in Example 6 of this invention in deuterium dimethyl sulfoxide;

[0066] Figure 10 This is the 1H NMR spectrum of compound PQ-L2 molecule prepared in deuterated dichloromethane in Example 7 of this invention;

[0067] Figure 11 This is the carbon NMR spectrum of compound PQ-L2 molecule prepared in Example 7 of this invention in deuterated trichloromethane;

[0068] Figure 12 This is the ultraviolet absorption spectrum of PQ-L1, PQ-L2, PQ-L3 and PQ-L4 molecules prepared in the embodiments of the present invention in tetrahydrofuran;

[0069] Figure 13 The fluorescence emission spectra of PQ-L1, PQ-L2, PQ-L3 and PQ-L4 molecules prepared in the embodiments of the present invention in tetrahydrofuran;

[0070] Figure 14 The PQ-L4 molecule prepared in Example 5 of this invention is in tetrahydrofuran / water ( V / V Fluorescence emission spectra in a mixed solvent;

[0071] Figure 15 The PQ-L4 molecule prepared in Example 5 of this invention is in tetrahydrofuran / water ( V / V Fluorescence intensity map in a mixed solvent;

[0072] Figure 16 This is an image of the PQ-L4 molecule prepared in Example 5 of this invention in a mouse brain vascular imaging experiment. Detailed Implementation Plan

[0073] Example 1

[0074] Preparation of the first intermediate

[0075] Under nitrogen protection at 0°C, a magnetic stir bar, dichloromethane (200 ml), triphenylamine (7.35 g, 0.03 mol), and anhydrous aluminum chloride (1.33 g, 0.01 mol) were added to a clean two-necked flask, followed by stirring. Oxaloyl chloride (1.26 g, 0.01 mol) was added dropwise while maintaining the reaction temperature at 0°C, and the mixture was stirred at room temperature for 6 h. The organic layer was separated using a separatory funnel, and then purified by extraction with water and dichloromethane sequentially to obtain the organic phase. Anhydrous sodium sulfate was added to the organic phase for drying, and the solvent was removed by vacuum distillation to obtain a green powdery product. Petroleum ether / ethyl acetate was used as the eluent (PE:EA = 3:1). V:V The solid was separated by column chromatography to obtain 2.77 g of yellow solid, yield: 51%.1 H NMR (400 MHz, DMSO) δ 7.74 (d, J = 9.0 Hz, 4 H), 7.39-7.33 (t, J =8.4 Hz, 8 H), 7.21-7.13 (m, 12 H), 6.78 (d, J = 9.0 Hz, 4 H). The 1H NMR spectrum is shown below. Figure 1 As shown.

[0076] Example 2

[0077] Preparation of the second intermediate

[0078] A magnetic stir bar, anhydrous ethanol (100 ml), intermediate 1 (2.17 g, 4 mmol), 1,2,4,5-phenyltetramine tetrahydrochloride (1.05 g, 3.7 mmol), potassium carbonate (1 g, 7.2 mmol), and water (5 ml) were added to a clean two-necked flask. The mixture was stirred for 12 h under nitrogen protection at 85 °C. The mixture was then filtered and dried to give 2.05 g of a yellow solid, yield: 86%. 1 H NMR (400 MHz, CD2Cl2) δ 7.37 (d, J = 8.7 Hz, 4 H), 7.27-723. (t, J = 6.4 Hz, 8 H),7.21 (s, 2 H), 7.10 (d, J = 6.4 Hz, 8 H), 7.05-7.00 (t, J = 7.7 Hz, 4 H), 6.98 (d, J = 7.2 Hz, 4 H), 4.03 (s, 4 H). The 1H NMR spectrum is shown below. Figure 2 As shown.

[0079] Example 3

[0080] Preparation of compound PQ-L1

[0081] Add a magnetic stir bar, acetic acid (20 ml), degassed dichloromethane (10 ml), intermediate 2 (0.64 g, 1 mmol), and glyoxal (0.11 g, 2 mmol) to a clean two-necked flask. Reflux the reaction mixture under nitrogen protection with stirring for 6 h. Then, neutralize the acetic acid with sodium bicarbonate. Extract and purify the resulting organic layer sequentially with water and dichloromethane to obtain the organic phase. Dry the organic phase with anhydrous sodium sulfate. Remove the solvent from the dried organic phase by vacuum distillation, using petroleum ether / dichloromethane as the eluent (PE:DCM = 1:2). V:V The sample was purified by chromatography to obtain 0.21 g of a brownish-red solid, yield: 31%. 1 H NMR (500 MHz, CD2Cl2) δ 8.92 (s, 2 H), 8.83. (s, 2 H), 7.54 (d, J =7.6 Hz, 4 H), 7.33-7.27 (t, J = 6.7 Hz, 8 H), 7.13 (d, J = 8.7 Hz, 8 H), 7.13-7.08 (t, J = 8.3 Hz, 4 H), 7.03 (d, J = 9.0 Hz, 4 H). The 1H NMR spectrum is shown below. Figure 3 As shown.

[0082] 13 C10 NMR (126 MHz, CD2Cl2) δ 155.81, 149.83, 147.54, 176.13, 142.39, 140.69, 132.46, 131.60, 130.06, 129.16, 125.89, 124.42, 121.92. The C10 NMR spectra are shown below. Figure 4 As shown.

[0083] Example 4

[0084] Preparation of compound PQ-L3

[0085] A magnetic stir bar was added to a clean two-necked flask, along with freshly distilled toluene (25 ml), pyridine (10 ml), intermediate 1 (1.63 g, 3 mmol), and 1,2,4,5-phenyltetramine tetrahydrochloride (0.17 g, 1 mmol). The reaction mixture was refluxed and stirred for 48 h under nitrogen protection at 20 °C. The resulting organic layer was purified by extraction with water and dichloromethane sequentially after filtration to obtain the organic phase. Anhydrous sodium sulfate was added to the organic phase for drying. The dried organic phase was then subjected to vacuum distillation to remove the solvent, using petroleum ether / dichloromethane as the eluent (PE:DCM = 1:3). V:V The sample was purified by chromatography to obtain 0.42 g of a brownish-red solid, yield: 37%. 1 H NMR (500 MHz, CD2Cl2) δ 8.76 (s, 2 H), 7.55. (d, J = 8.2 Hz, 8 H), 7.32-7.28 (t, J = 9.1 Hz, 16 H), 7.17-7.08 (m, 24 H), 7.03 (d, J = 7.4 Hz, 8 H). The 1H NMR spectrum is shown below. Figure 5 As shown.

[0086] 13 C10 NMR (126 MHz, CD2Cl2) δ 154.73, 149.20, 147.40, 140.48, 132.39, 131.15, 130.69, 126.57, 124.37, 123.89, 122.32. The C10 NMR spectra are shown below. Figure 6 As shown.

[0087] Example 5

[0088] Preparation of compound PQ-L4

[0089] Add a magnetic buoy to a clean two-necked flask, along with degassed dichloromethane (25 ml), compound PQ-L3 (115 mg, 0.1 mmol), and... N19 mg of bromosuccinimide (0.11 mmol) was added dropwise to a stirred solution with 3 drops of acetic acid. The reaction mixture was stirred for 3 h under nitrogen protection at room temperature. The resulting organic layer was purified by extraction with water and dichloromethane sequentially to obtain an organic phase. Anhydrous sodium sulfate was added to the organic phase for drying. The dried organic phase was then distilled under reduced pressure to remove the solvent, yielding 125 mg of a yellow solid (yield: 96%). The obtained yellow solid (131.02 mg, 0.1 mmol) was dissolved in freshly distilled toluene (30 ml), and 72 mg of 4-boronic acid triphenylamine (0.25 mmol), 11.55 mg of tetra(triphenylphosphine)palladium (0.01 mmol), 55.28 mg of potassium carbonate (0.4 mmol), and 1 ml of water were added. The mixture was stirred for 24 h under nitrogen protection at 120 °C. The obtained organic layer was purified by extraction with water and dichloromethane sequentially after filtration to obtain an organic phase. Anhydrous sodium sulfate was added to the organic phase for drying. The dried organic phase was then subjected to vacuum distillation to remove the solvent, using petroleum ether / dichloromethane as the eluent (PE:DCM, DCM = 1:2, 1, V:V The sample was purified by chromatography to obtain 144 mg of a purple-red solid, yield: 88%. 1 H NMR (500 MHz, CD2Cl2) δ 7.79 (d, J = 8.4 Hz, 4 H), 7.59 (d, J =9.0 Hz, 8 H), 7.32-7.27 (t, J = 9.2 Hz, 16 H), 7.26–7.19 (m, 20 H), 7.17–7.08 (m, 24 H), 6.99 (m, 12 H). The 1H NMR spectrum is shown below. Figure 7 As shown.

[0090] 13 C10 NMR (126 MHz, CD2Cl2) δ 152.51, 149.80, 148.51, 137.84, 135.93, 132.78, 131.77, 130.26, 126.16, 125.81, 125.23, 124.56, 121.98. The C10 NMR spectrum is shown below. Figure 8 As shown.

[0091] Example 6

[0092] Preparation of intermediate 3

[0093] Add a magnetic stir bar, anhydrous ethanol (50 ml), water (5 ml), 1,2,4,5-phenyltetramine tetrahydrochloride (1.74 g, 0.01 mol), and sodium acetate (3.28 g, 0.04 mol) to a clean two-necked flask. Stir at room temperature for 10 min, then add glyoxal (2.32 g, 0.04 mol). Stir the reaction mixture at 75 °C for 6 h. Concentrate the mixture, and add water (10 ml) and saturated sodium bicarbonate (20 ml) to the residue. Extract the mixture three times with diethyl ether (30 ml), wash the organic phase three times with brine, and dry with anhydrous sodium sulfate. After solvent removal, elute with n-hexane / ethanol (HEX:EtOH = 5:1). V:V The sample was purified by chromatography to obtain 0.92 g of a yellow solid. Yield: 51%. 1 1H NMR (500 MHz, DMSO) δ 9.10 (s, 4 H), 8.86 (s, 2 H). The 1H NMR spectrum is shown below. Figure 9 As shown.

[0094] Example 7

[0095] Preparation of compound PQ-L2

[0096] Add a magnetic flask containing degassed DMF (25 ml), intermediate 3 (182 mg, 1 mmol), and... N 3-Bromosuccinimide (359.51 mg, 2.02 mmol) was added dropwise to the stirred solution with 3 drops of acetic acid. The reaction mixture was stirred for 16 h under nitrogen protection at 60 °C. The reaction mixture was cooled to 24 °C, diluted with H2O (10 ml), and filtered. The precipitate was washed with H2O (100 ml) and cold CH2Cl2 (100 ml). The precipitate (168 mg, 0.5 mmol) was dissolved in freshly distilled toluene, and triphenylamine 4-borate (578.24 mg, 2 mmol), tetrakis(triphenylphosphine)palladium (11.55 mg, 0.01 mmol), potassium carbonate (276 mg, 2 mmol), and water (2 ml) were added. The mixture was stirred for 24 h under nitrogen protection at 120 °C. The obtained organic layer was purified by extraction with water and dichloromethane sequentially after filtration to obtain an organic phase. Anhydrous sodium sulfate was added to the organic phase for drying. The dried organic phase was then subjected to vacuum distillation to remove the solvent, using petroleum ether / dichloromethane as the eluent (PE:DCM, DCM = 1:1). V:V The sample was purified by chromatography to obtain 220 mg of a purple-red solid, yield: 64%. 1HNMR (500 MHz, CD2Cl2) δ 8.90 (s, 4 H), 7.50 (d, J = 6.8 Hz, 4 H), 7.35-7.33 (t, J = 8.9 Hz, 8 H), 7.26 (d, J = 7.4 Hz, 8 H), 7.20 (m, 4 H), 7.12-7.09 (t, J =7.5 Hz, 4 H). The 1H NMR spectrum is shown below. Figure 10 As shown.

[0097] 13 C10 NMR (126 MHz, CDCl3) δ 148.02, 147.82, 145.96, 143.59, 139.65, 134.11, 129.72, 127.46, 125.91, 123.87, 121.11. The C10 NMR spectra are shown below. Figure 11 As shown.

[0098] Experimental Example 1

[0099] 1. Absorption, molar absorptivity, and emission spectrum:

[0100] PQ-L1, PQ-L2, PQ-L3, and PQ-L4 were dissolved in THF to prepare a 10 μM solution, and ultraviolet absorption (Shimadzu UV-1600i) and fluorescence emission spectroscopy were performed (Edinburgh fluorescence spectrometer). Figure 12 As shown, the absorption peaks of PQ-L1, PQ-L2, PQ-L3, and PQ-L4 are 478 nm, 515 nm, 520 nm, and 540 nm, respectively. Figure 13 As shown, the emission spectral peaks of PQ-L1, PQ-L2, PQ-L3 and PQ-L4 are 650 nm, 757 nm, 658 nm and 717 nm, respectively, and all four molecules have significant deep red and near-infrared emission properties.

[0101] Experimental Example 2

[0102] 2. AIE curve test:

[0103] Solutions (10 μM) of PQ-L1, PQ-L2, PQ-L3, and PQ-L4 in THF / water mixed solvents with water contents ranging from 0% to 99% were prepared and their emission spectra were measured. Figure 14 The image shows the emission spectra of PQ-L1, PQ-L2, PQ-L3, and PQ-L4 molecules in solvents with different water contents. Figure 15The curves show the variation of peak emission intensity with different water ratios.

[0104] Experimental Example 3

[0105] 3. In vivo deep brain imaging

[0106] Craniotomy was performed on anesthetized mice. The craniotomy center was located 2 mm posterior and lateral to the Bregma point, and the cranial window was sealed with a 5 mm diameter transparent glass slide to allow light to enter the mouse brain. PQ-L4 nanoparticles were injected into the mice via orbital injection, and imaging was performed after injection. Imaging was performed using a 1 MHz 1550 nm fiber laser (FLCPA-02CSZU, Calmar) as the pump, generating 2200 nm frequency-shifted soliton pulses in a large-mode-field fiber. After long-pass filtering to remove residual pump, half-wave plates, and polarization beam splitters to control the optical power, the soliton pulses were used for laser scanning microscopy of the MPM. Water immersion objectives were used for all imaging experiments, and image acquisition and processing were performed using ScanImage and ImageJ software, respectively. Figure 16 As shown, the imaging depth is 650 nm.

[0107] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. An aggregation-induced emission material with multiphoton absorption properties, characterized in that, The structural formula of the aggregation-induced emission material is: 。 2. A method for preparing the aggregation-induced emission material as described in claim 1, characterized in that, The preparation method includes the following steps: The first intermediate, 1,2,4,5-phenyltetramine tetrahydrochloride, was dispersed in a mixed solution of toluene and pyridine and stirred under inert gas protection at 20°C to obtain compound PQ-L3. Add the compound PQ-L3 and N-bromosuccinimide to dichloromethane, stir the solution and add acetic acid dropwise; stir the reaction mixture at room temperature for 0.5-2 h. After removing the solvent, the residue was dissolved in freshly distilled toluene, and then 4-boronic acid triphenylamine, tetra(triphenylphosphine)palladium and potassium carbonate aqueous solution were added. The mixture was stirred for 24 h at 120 °C under nitrogen protection to obtain the aggregation-induced luminescence material. The structural formula of the first intermediate is ; The structural formula of the compound PQ-L3 is: 。 3. The application of the aggregation-induced emission material with multiphoton absorption properties as described in claim 1 in multiphoton fluorescence imaging, for non-diagnostic and non-therapeutic purposes.

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