A near-infrared luminescent material based on an aryl-fused indole donor, its preparation method and applications

Abstract

The present invention discloses a near-infrared luminescent material based on an aryl-fused indole donor, its preparation method and applications, belonging to the technical field of organic optoelectronic semiconductors. The near-infrared luminescent material has a D-A-D structure, and the electron donor and acceptor core units in its molecular structure ensure its aggregation-induced emission characteristics. The selection of a strong electron acceptor promotes the absorption / emission wavelength of the molecule to the near-infrared region. The near-infrared luminescent material involved in the present invention has a simple synthesis route, low cost, controllable energy levels, excellent luminescence behavior, good fluorescence quantum yield and good photodynamic / photothermal effects, and can be widely applied in the fields of organic semiconductor devices, biosensing, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic optoelectronic semiconductors, and particularly relates to a near-infrared luminescent material based on an aryl-fused indole donor, a preparation method thereof, and an application thereof. Background Art

[0002] Organic optoelectronic semiconductor materials have the properties of strong structural designability, adjustable energy levels, adjustable spectra, broad-spectrum absorption, and strong fluorescence emission. They have become the main body of a new generation of electronic information materials and have received extensive attention and applications in the fields of organic light-emitting diodes, organic field-effect transistors, organic solar cells, perovskite solar cells, photodetectors, and biosensing and diagnosis and treatment. Research and development of new and efficient organic conjugated semiconductor materials will surely have a broad market prospect in the electronics industry. Organic semiconductor materials with near-infrared absorption and emission properties have been widely used in the fields of organic electronics devices, nano-biology, and flexible electronics. Currently, most of the most widely studied fluorescent materials emit wavelengths in the visible light region (400 - 700 nm) and the first near-infrared region (700 - 900 nm). However, in this wavelength band, the light energy intensity is high, the light scattering degree is high, and the penetration depth into biological tissues is shallow, making it difficult to reach deep tissues. In contrast, the development of near-infrared II (NIR-II, 1000 - 1700 nm) emission optical diagnosis and treatment materials can effectively make up for the above deficiencies and maximize the advantages of optical diagnosis and treatment materials.

[0003] Compared with inorganic and polymer materials, organic small molecule materials have become an excellent choice for constructing optical diagnosis and treatment materials due to their easy modification, exact structure / purity, and good biocompatibility. However, in a physiological environment, hydrophobic polycyclic aromatic compounds will inevitably form clusters, accompanied by strong intermolecular π-π interactions, promoting aggregation and resulting in the occurrence of the fluorescence quenching (ACQ) phenomenon. Compared with traditional dye molecules, AIE (aggregation-induced emission) molecules with a propeller-like conformation emit bright fluorescence in the aggregated state because the intramolecular motion is restricted, and the excited state energy is mainly dissipated through the radiative transition pathway; at the same time, the twisted AIE molecules can still dissipate the excited state energy through the local motion of multiple rotor units via the non-radiative transition pathway, and then be used for PAI (photoacoustic imaging), PTI (photothermal imaging), and PTT (photothermal therapy). Therefore, through reasonable molecular design, controllable regulation between radiative transition and non-radiative transition in the excited state energy of NIR-II AIE molecules can be achieved. Summary of the Invention

[0004] The present invention provides a near-infrared luminescent material, a preparation method thereof, and an application thereof to obtain a near-infrared organic semiconductor with more beneficial properties, richer structures, and easier functionalization and large-scale production.

[0005] Technical solution: A near-infrared luminescent material based on an arylbenzoindole donor, and the general chemical structure formula of the near-infrared luminescent material is shown as follows:

[0006]

[0007] Wherein, A is or , X is O, S, Se, Te or N-R, and R is selected from: substituted or unsubstituted C1-C24 alkyl (linear or branched alkyl of C1-C24), alkoxy chain containing C3-C24, aryl with 1-2 linear or branched alkyl of C1-C24.

[0008] The R 1 and R 2 are independently selected from: linear or branched alkyl of C1-C24.

[0009] The Ar 1 and Ar 2 are each independently selected from: substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C4-C30 heteroaryl.

[0010] Preferably, in the near-infrared luminescent material, A is any one of the following structures:

[0011]

[0012]

[0013] Preferably, in the near-infrared luminescent material, Ar1 and Ar2 are each independently any one of the following structures:

[0014]

[0015] Wherein, R3 to R5 are each independently selected from: deuterium, F, Cl, Br, I, CN; C1-C24 alkyl; C1-C24 alkoxy; substituted or unsubstituted aryl, and the aryl includes phenyl, biphenyl, naphthyl, triphenylene, anthryl, pyrenyl, phenanthryl, chrysenyl and perylenyl, and the substituents are deuterium, F, Cl, CN, C1-C24 alkyl, C1-C24 alkoxy.

[0016] Furthermore, the near-infrared luminescent material includes the following compounds:

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035] The present invention provides a method for preparing the near-infrared luminescent material, specifically: adding a bromine- or chlorine-containing compound of the acceptor unit, a donor unit compound, and a catalyst into a solvent to obtain a reaction solution; after purifying the reaction solution through a silica gel column, recrystallizing to obtain a powdery near-infrared luminescent material. The donor unit and the acceptor unit undergo a Stille coupling reaction to obtain a near-infrared luminescent fluorescent molecular compound.

[0036] In the structure of the near-infrared luminescent material, when the two sides of A are symmetric structural formulas, the synthesis reaction formula is as follows:

[0037] 。

[0038] In the structure of the near-infrared luminescent material, when the two sides of A are asymmetric structural formulas, the synthesis reaction formula is as follows:

[0039] 。

[0040] Preferably, in the reaction solution, the molar concentration of the acceptor unit is 0.1 - 2.0 mmol / mL, the molar ratio of the acceptor unit to the donor unit is 1:(2.1 - 2.6), the molar ratio of the catalyst to the reaction substrate is (0.02 - 4.00):100, and the reaction substrate refers to the acceptor unit and the donor unit; the catalyst is palladium tetrakis(triphenylphosphine); the solvent is one of toluene, chlorobenzene, and xylene, preferably ultra-dry deoxygenated toluene.

[0041] Preferably, in the preparation method, the reaction temperature is 100 - 120 °C and the reaction time is 8 h.

[0042] Preferably, in the preparation method, the step of purifying the reaction solution to obtain the near-infrared luminescent material includes: purifying the reaction solution through a silica gel column with a detergent of dichloromethane:petroleum ether (volume ratio 3:10), and then recrystallizing with dichloromethane and methanol to obtain a powdery near-infrared luminescent material.

[0043] The near-infrared luminescent material prepared by the present invention can be used in organic optoelectronic devices or biological sensors and imaging devices. Specifically, it can be applied to the functional layer of an organic light-emitting diode device, such as the light-emitting layer; used in the perovskite solar cell composition of a perovskite solar cell device as a hole transport layer; in the field of biosensing and imaging, the near-infrared luminescent material can be used as the light absorption and light emission unit of a nanoprobe or photosensitizer.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1) The fluorescence emission peak of the compound of the present invention appears in the range of 700 - 1600 nm.

[0046] 2) The compound of the present invention has a multiple D-A structure with strong donor characteristics and strong acceptor characteristics, is a near-infrared fluorescent luminescent molecule, has a high triplet energy level, a small ΔEST, a high PLQY, near-infrared luminescence, high stability, and a high glass transition temperature.

[0047] The arrangement of donor units in the molecule can, on the one hand, effectively regulate the overlap of electron clouds between the donor and acceptor, significantly affect the energy levels, band gap, and triplet excited state energy levels, and improve the singlet-triplet energy level difference (△Est); on the other hand, the close-packing connection mode between the donor and acceptor is affected by the dihedral angle of the bridging structure, and a better photoluminescence efficiency (PLQY) can be obtained. At the same time, the three-dimensional molecular structure of the donor part and the rigid planar large-conjugated structure of the acceptor unit affect its molecular crystallinity, and the packing mode of the molecule in the aggregated state can be effectively regulated, so that the compound of the present invention has better morphological stability and excellent film stability in the electroluminescent device, which is beneficial to the corresponding device life and is conducive to improving the performance and luminous efficiency of the OLED device. Multiple electron-rich donor units are beneficial to obtaining high HOMO energy levels and balanced electron and hole transport characteristics, which is beneficial to their application in perovskite solar cell devices.

[0048] The molecule of the present invention has multiple donor monomers, which cause a shielding effect on the close packing between the donor and acceptor units, which is beneficial to maintaining a high fluorescence quantum efficiency in the solid state or condensed state and is beneficial to its application in fluorescence imaging; its absorption and emission characteristics in the second near-infrared region are beneficial to its application in second-region imaging and photoacoustic imaging; its near-infrared absorption characteristics are beneficial to its application in photothermal therapy; its low singlet-triplet energy level difference is beneficial to intramolecular intersystem crossing, thereby obtaining a long-lived triplet state, which is beneficial to its application in photodynamic therapy.

[0049] 3) The starting materials for the preparation of the compounds of the present invention are easy to obtain, the synthesis route is simple, the reaction conditions are mild, the operation steps are simple, and the cost is low, which is beneficial to large-scale production. The energy levels of the compounds of the present invention are controllable, the luminescence behavior is excellent, and they have good fluorescence quantum yields and good photodynamic / photothermal effects. Description of the Drawings

[0050] Figure 1 It is the ultraviolet absorption spectra of the near-infrared fluorescent molecules A-7 and C-7 in Example 1 and Example 2 of the present invention.

[0051] Figure 2 It is the fluorescence emission spectra of the near-infrared fluorescent molecules A-7 and C-7 in Example 1 and Example 2 of the present invention.

[0052] Figure 3 It is the near-infrared photothermal heating curve of the nanoparticles prepared from the near-infrared fluorescent molecule A-7 in Example 1 of the present invention relative to water.

[0053] Figure 4 It is the near-infrared photothermal heating curve of the nanoparticles prepared from the near-infrared fluorescent molecule C-7 in Example 2 of the present invention relative to water. Detailed Description of the Invention

[0054] The technical solution of the present invention will be described in detail below through embodiments, but the protection scope of the present invention is not limited to the described embodiments.

[0055] The present invention discloses a near-infrared luminescent material based on an aryl-fused indole donor, its preparation method and application. This near-infrared luminescent material has advantages such as high luminous efficiency, tunable emission wavelength, low synthesis cost, and good stability. The present invention introduces a conjugated acceptor center structure at specific sites with an electron-rich conjugated group having hole-transporting properties to construct a brand-new near-infrared luminescent fluorescent molecule, which can obtain a near-infrared organic semiconductor with more beneficial properties, richer structures, and easier functionalization and large-scale production.

[0056] In this specification, when no other definition is provided, "substituted" means that at least one hydrogen of a substituent or a compound is replaced by deuterium, halogen, cyano, substituted or unsubstituted C1-C24 alkyl, C3-C24 cycloalkyl, C6-C24 aryl, C2-C24 heteroaryl, or a combination thereof.

[0057] In this specification, when no other definition is provided, "alkyl" refers to an aliphatic hydrocarbon group. The alkyl can be C1-C24 alkyl. More specifically, the alkyl can be C1-C20 alkyl or C1-C10 alkyl. For example, C1-C4 alkyl can have 1 to 4 carbon atoms in the alkyl chain and can be selected from methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl.

[0058] Specific examples of the alkyl can be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.

[0059] In this specification, "aryl" refers to a group including at least one hydrocarbon aromatic moiety, and all elements of the hydrocarbon aromatic moiety have p-orbitals forming conjugation, such as phenyl, naphthyl, etc. Two or more hydrocarbon aromatic moieties can be connected by a σ bond and can be, for example, biphenyl, terphenyl, quaterphenyl, etc., or two or more hydrocarbon aromatic moieties are directly or indirectly fused to provide a non-aromatic fused ring. For example, it can be fluorenyl. The aryl can include monocyclic, polycyclic, or fused polycyclic (i.e., rings sharing adjacent carbon atom pairs) functional groups.

[0060] Example 1

[0061] This example provides a structure specifically shown as Formula A-7:

[0062]

[0063] The preparation method of Compound A-7 specifically includes the following steps:

[0064]

[0065] Step 1): Synthesis of Compound I

[0066] In a 500 mL two-necked flask, add 2,5-dibromonitrobenzene (10 g, 35.6 mmol), 2-thiopheneboronic acid (5.47 g, 42.7 mmol), anhydrous potassium carbonate (9.83 g, 71.2 mmol), tetrahydrofuran (100 mL), and water (25 mL). After purging with nitrogen for 15 min, under a nitrogen stream, add tetrakis(triphenylphosphine)palladium (110 mg). The reaction is carried out under nitrogen protection and heated at 80 °C for 4 h. After the reaction is completed, cool the reaction to room temperature, extract with dichloromethane and water, pass through anhydrous sodium sulfate, remove the solvent, and purify by silica gel column to obtain a bright yellow oily substance (7.3 g, 76% yield). HR-MS (ACPI-M + , m / z): 284.13.

[0067] Step 2): Synthesis of Compound II

[0068] In a 250 mL two-necked flask, add Compound I (5 g, 17.6 mmol), triphenylphosphine (13.8 g, 52.6 mmol), and ultra-dry chlorobenzene (30 mL). After purging with nitrogen for 15 min, reflux and heat at 140 °C overnight. After the reaction is completed, cool the reaction to room temperature, distill off chlorobenzene under reduced pressure, purify by silica gel column, and recrystallize to obtain a yellowish-white powder product (4.2 g, 80% yield). HR-MS (ACPI-M + , m / z): 252.13.

[0069] Step 3): Synthesis of Compound III

[0070] In a 250 mL two-necked flask, add Compound II (5 g, 19.8 mmol), 1-bromohexane (4.26 g, 19.8 mmol), potassium hydroxide (3.34 g, 59.5 mol), potassium iodide (0.33 g, 0.2 mol), and ultra-dry tetrahydrofuran (30 mL). After purging with nitrogen for 15 min, heat at 70 °C for 4 h. After the reaction is completed, cool the reaction to room temperature, extract with dichloromethane and water, pass through anhydrous sodium sulfate, remove the solvent, and purify by silica gel column to obtain a pale yellow oily substance (4.5 g, 95% yield). HR-MS (ACPI-M + , m / z): 336.29.

[0071] Step 4): Synthesis of Compound IV

[0072] In a 100 mL two-necked flask, add compound Ⅲ (2 g, 5.9 mmol), ultra-dry tetrahydrofuran (15 mL). After purging with nitrogen for 15 min, cool the mixture to -78 °C and slowly add n-butyllithium (3.8 mL) dropwise. After the addition is complete, the system turns light yellow. Without controlling the temperature, let it warm up to -50 °C naturally and maintain for 10 min. Then, cool it slowly to -78 °C again and quickly add tributyltin chloride (2.13 g, 6.5 mmol). Subsequently, let it warm up to room temperature naturally, and the system turns yellow. After stirring for 4 h, first add petroleum ether and then dropwise add water, and the system gradually becomes transparent. The mixture is extracted with water and petroleum ether, passed through anhydrous sodium sulfate, and the solvent is removed to obtain the crude compound (1.6 g, yield 82%). HR-MS(ACPI-M + , m / z): 546.45.

[0073] Step V): Synthesis of compound Ⅴ

[0074] In a 100 mL two-necked flask, add compound Ⅳ (2 g, 3.7 mmol), 4,8-dibromo-1H,5H-benzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (0.61 g, 1.7 mmol), tetrakis(triphenylphosphine)palladium (10 mg), deoxygenated toluene (15 mL). After purging with nitrogen for 15 min, heat at 100 °C for 4 h. After the reaction is completed, cool the reaction to room temperature, remove the solvent, and purify by silica gel column to obtain a dark green product (0.5 g, product 62%). HR-MS(ACPI-M + , m / z): 704.99.

[0075] Example 2

[0076] This example provides a structure specifically shown in Formula C-7:

[0077]

[0078] The preparation method of compound C-7 specifically includes the following steps:

[0079]

[0080] Step I): Synthesis of compound Ⅰ

[0081] In a 250 mL two-necked flask, 3-bromocarbazole (5 g, 20.3 mmol), 1-bromohexane (4.36 g, 26.4 mmol), potassium hydroxide (3.42 g, 70.0 mmol), potassium iodide (0.34 g, 2.0 mmol), and ultra-dry tetrahydrofuran (30 mL) were added. After purging with nitrogen for 15 min, the mixture was heated at 70 °C for 4 h. After the reaction was completed, the reaction was cooled to room temperature, extracted with dichloromethane and water, passed through anhydrous sodium sulfate, the solvent was removed, and purified by silica gel column chromatography to obtain a transparent oily substance (4.8 g, 96% yield). HR-MS(ACPI-M + , m / z): 330.27.

[0082] Step 2): Synthesis of Compound II

[0083] In a 100 mL two-necked flask, Compound I (2 g, 6.1 mmol) and ultra-dry tetrahydrofuran (15 mL) were added. After purging with nitrogen for 15 min, the temperature was lowered to -78 °C and n-butyllithium (3.8 mL) was added dropwise. After the addition was completed, the system turned light yellow. Without controlling the temperature, the temperature was naturally raised to -50 °C and maintained for 10 min. Then, the temperature was slowly lowered to -78 °C again and tributyltin chloride (2.17 g, 6.7 mmol) was quickly added. Subsequently, the temperature was naturally raised to room temperature and the system was yellow. After stirring for 4 h, petroleum ether was added first and then water was added dropwise, and the system gradually became transparent. The mixture was extracted with water and petroleum ether, passed through anhydrous sodium sulfate, and the solvent was removed to obtain a crude compound (1.72 g, 85% yield). HR-MS(ACPI-M + , m / z): 540.42.

[0084] Step 3): Synthesis of Compound III

[0085] In a 100 mL two-necked flask, Compound II (2 g, 3.7 mmol), 4,8-dibromo-1H,5H-benzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (0.62 g, 1.8 mmol), tetrakis(triphenylphosphine)palladium (10 mg), and deoxygenated toluene (15 mL) were added. After purging with nitrogen for 15 min, the mixture was heated at 100 °C for 4 h. After the reaction was completed, the reaction was cooled to room temperature, the solvent was removed, and purified by silica gel column chromatography to obtain a dark green product (0.53 g, 69% of the product). HR-MS(ACPI-M + , m / z): 692.94.

[0086] Example 3

[0087] This example provides a structure specifically shown in Formula B-7:

[0088]

[0089] The preparation method of compound B-7 specifically includes the following steps:

[0090]

[0091] Step 1): Synthesis of compound I

[0092] In a 500 mL two-necked flask, add 2,5-dibromonitrobenzene (10 g, 35.6 mmol), thiophene[3,2-b]thiophene tin reagent (16.8 g, 39.1 mmol). After purging with nitrogen for 15 min, under a nitrogen stream, add tetrakis(triphenylphosphine)palladium (560 mg). The reaction is carried out under nitrogen protection and heated at 120 °C for 24 hours. After the reaction is completed, cool the reaction to room temperature, extract with dichloromethane and water, filter through anhydrous sodium sulfate, remove the solvent, and purify by silica gel column to obtain a brownish-red solid (6.2 g, 60% yield). HR-MS(ACPI-M + , m / z): 340.21.

[0093] Step 2): Synthesis of compound II

[0094] In a 250 mL two-necked flask, add compound I (5 g, 14.7 mmol), triphenylphosphine (11.6 g, 44.2 mmol), super-dry chlorobenzene (30 mL). After purging with nitrogen for 15 min, reflux and heat at 140 °C overnight. After the reaction is completed, cool the reaction to room temperature, distill off chlorobenzene under reduced pressure, purify by silica gel column, and then recrystallize to obtain a yellowish-white powder product (3.2 g, 56% yield). HR-MS(ACPI-M + , m / z): 308.21.

[0095] Step 3): Synthesis of compound III

[0096] In a 250 mL two-necked flask, add compound II (5 g, 16.2 mmol), 1-bromohexane (2.7 g, 16.4 mmol), potassium hydroxide (2.7 g, 48.1 mmol), potassium iodide (0.27 g, 1.6 mmol), super-dry tetrahydrofuran (30 mL). After purging with nitrogen for 15 min, heat at 70 °C for 4 hours. After the reaction is completed, cool the reaction to room temperature, extract with dichloromethane and water, filter through anhydrous sodium sulfate, remove the solvent, and purify by silica gel column to obtain a pale yellow oily substance (4.5 g, 95% yield). HR-MS(ACPI-M + , m / z): 392.37.

[0097] Step 4): Synthesis of compound IV

[0098] In a 100 mL two-necked flask, add compound Ⅲ (2 g, 5.1 mmol), ultra-dry tetrahydrofuran (15 mL). After purging with nitrogen for 15 min, cool the temperature to -78 °C and add n-butyllithium (3.2 mL) dropwise. After the addition is complete, the system turns light yellow. Without controlling the temperature, let it warm up to -50 °C naturally and maintain for 10 min. Then, cool it slowly to -78 °C again and quickly add tributyltin chloride (1.69 g, 5.2 mmol). Subsequently, let it warm up to room temperature naturally, and the system is yellow. After stirring for 4 hours, first add petroleum ether and then dropwise add water, and the system gradually becomes transparent. The mixture is extracted with water and petroleum ether, passed through anhydrous sodium sulfate, and the solvent is removed to obtain the crude compound (1.5 g, yield 72%). HR-MS(ACPI-M + , m / z): 602.53.

[0099] Step V): Synthesis of compound Ⅴ

[0100] In a 100 mL two-necked flask, add compound Ⅳ (2 g, 3.3 mmol), 4,8-dibromo-1H,5H-benzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (0.55 g, 1.56 mmol), tetrakis(triphenylphosphine)palladium (10 mg), deoxygenated toluene (15 mL). After purging with nitrogen for 15 min, heat at 100 °C for 4 hours. After the reaction is completed, cool the reaction to room temperature, remove the solvent, and purify by silica gel column to obtain a dark green product (0.5 g, product 65%). HR-MS(ACPI-M + , m / z): 817.15.

[0101] Example 4

[0102] This example provides a structure specifically shown as formula E-1:

[0103]

[0104] The preparation method of compound E-1 specifically includes the following steps:

[0105]

[0106] Step I): Synthesis of compound Ⅰ

[0107] In a 500 mL two-necked flask, 2-naphthaleneboronic acid (10 g, 58.1 mmol), 4-bromo-1-iodo-2-nitrobenzene (19.1 g, 58.1 mmol), potassium carbonate (9.6 g, 69.5 mmol), water (20 mL), and dioxane (120 mL) were added. After purging with nitrogen for 15 min, under a nitrogen stream, tetrakis(triphenylphosphine)palladium (600 mg) of the compound was added; the reaction was carried out under nitrogen protection and heated at 60 °C for 8 h. After the reaction was completed, the reaction was cooled to room temperature, extracted with dichloromethane and water, passed through anhydrous sodium sulfate, the solvent was removed, and purified by silica gel column to obtain a pale yellow solid (7.8 g, 76% yield), HR-MS(ACPI-M + , m / z): 328.17.

[0108] Step 2): Synthesis of Compound II

[0109] In a 250 mL two-necked flask, Compound I (5 g, 15.2 mmol), triphenylphosphine (12.0 g, 45.8 mmol), and ultradry chlorobenzene (30 mL) were added. After purging with nitrogen for 15 min, the mixture was refluxed and heated at 140 °C overnight. After the reaction was completed, the reaction was cooled to room temperature, chlorobenzene was removed by distillation under reduced pressure, and after purification by silica gel column, recrystallization was carried out to obtain a yellowish-white powder product (3.2 g, 60% yield), HR-MS(ACPI-M + , m / z): 296.17.

[0110] Step 3): Synthesis of Compound III

[0111] In a 250 mL two-necked flask, Compound II (5 g, 16.9 mmol), 1-bromohexane (2.8 g, 16.9 mmol), potassium hydroxide (2.8 g, 50.7 mmol), potassium iodide (0.28 g, 1.6 mmol), and ultradry tetrahydrofuran (30 mL) were added. After purging with nitrogen for 15 min, the mixture was heated at 70 °C for 4 h. After the reaction was completed, the reaction was cooled to room temperature, extracted with dichloromethane and water, passed through anhydrous sodium sulfate, the solvent was removed, and purified by silica gel column to obtain a pale yellow oily substance (4.1 g, 91% yield), HR-MS(ACPI-M + , m / z): 380.33.

[0112] Step 4): Synthesis of Compound IV

[0113] In a 100 mL two-necked flask, add compound III (2 g, 5.3 mmol), ultra-dry tetrahydrofuran (15 mL). After purging with nitrogen for 15 min, cool the mixture to -78 °C and add n-butyllithium (3.2 mL) dropwise. After the addition is complete, the system turns light yellow. Without controlling the temperature, let it warm up to -50 °C naturally and keep it for 10 min. Then cool it slowly to -78 °C again and quickly add tributyltin chloride (1.75 g, 5.4 mmol). Subsequently, let it warm up to room temperature naturally, and the system becomes yellow. After stirring for 4 h, first add petroleum ether and then add water dropwise. The system gradually becomes transparent. The mixture is extracted with water and petroleum ether, passed through anhydrous sodium sulfate, and the solvent is removed to obtain the crude compound (1.1 g, yield 69%). HR-MS(ACPI-M + , m / z): 590.48.

[0114] Step (v): Synthesis of compound V

[0115] In a 100 mL two-necked flask, add compound IV (2 g, 3.4 mmol), 4,8-dibromo-1H,5H-benzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (0.57 g, 1.6 mmol), tetrakis(triphenylphosphine)palladium (10 mg), deoxygenated toluene (15 mL). After purging with nitrogen for 15 min, heat at 100 °C for 4 h. After the reaction is completed, cool the reaction to room temperature, remove the solvent, and purify by silica gel column to obtain a dark green product (0.6 g, product 68%). HR-MS(ACPI-M + , m / z): 793.06.

[0116] Perform performance tests on A-7 and C-7 prepared in Example 1 and Example 2. The results are as Figure 1 and Figure 2 shown. Figure 1 and Figure 2 are the ultraviolet absorption and fluorescence emission spectra of A-7 and C-7, respectively. Figure 1 and Figure 2 show that the compounds prepared by the present invention have long-wavelength emission effects in the second near-infrared region.

[0117] After A-7 and C-7 prepared in Example 1 and Example 2 are coated with F127 (also known as poloxamer 407, a commonly used non-ionic triblock copolymer), A-7 and C-7 nanoparticles are formed. The coating method is an existing method. Figure 3 and Figure 4 are the near-infrared photothermal heating curves of A-7 and C-7 nanoparticles relative to water, respectively. Figure 3 and Figure 4 In, 50 - 200 μg / mL refers to the concentration of the sample (the concentration of nanoparticles in ultrapure water). Figure 3 andFigure 4 It shows that the prepared nanoparticles have potential value for fluorescence imaging and photothermal therapy.

[0118] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as a limitation on the present invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A near-infrared luminescent material based on an aryl indole donor, characterized in that: The chemical structure formula of the near-infrared luminescent material is as follows: ； Among them, A is , X is S; R1 and R2 are independently selected from: C6 straight chain or branched alkyl; Ar1 ​​and Ar2 are independently selected from: or .

2. The near-infrared luminescent material according to claim 1, characterized in that: The near-infrared luminescent material is one of the following compounds: 。 3. The method for preparing the near-infrared luminescent material according to claim 1, characterized in that: The preparation method comprises: adding a bromine-containing compound of an acceptor unit, a compound of a donor unit, and a catalyst into a solvent to obtain a reaction solution; purifying the reaction solution through a silica gel column, and then recrystallizing the reaction solution to obtain a powdered near-infrared luminescent material; The structure of the bromine-containing compound of the receptor unit is ; The structure of the donor unit compound is or ; In the structure of the near-infrared luminescent material, when the left and right sides of A are symmetrical structural formulas, the synthesis reaction formula is as follows: ； In the structure of the near-infrared luminescent material, when the left and right sides of A are asymmetric structural formulas, the synthesis reaction formula is as follows: 。 4. The method for preparing the near-infrared luminescent material according to claim 3, characterized in that: In the reaction solution, the molar concentration of the bromine-containing compound of the acceptor unit is 0.1-2.0 mmol / mL, the molar ratio of the bromine-containing compound of the acceptor unit to the compound of the donor unit is 1:(2.01-2.6), the molar ratio of the catalyst to the reaction substrate is (0.02-4.00):100, the reaction substrate refers to the bromine-containing compound of the acceptor unit and the compound of the donor unit; the catalyst is tetrakistriphenylphosphine palladium; the solvent is one of toluene, chlorobenzene and xylene.

5. The method for preparing the near-infrared luminescent material according to claim 3, characterized in that: The reaction temperature is 100-120° C., and the reaction time is 4-8 h.

6. The use of the near-infrared luminescent material according to claim 1, characterized in that: The near-infrared luminescent material is used in organic optoelectronic devices or biosensors and imaging equipment.

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