A novel near-infrared two-region aggregation-induced emission molecule and a preparation method and application thereof

Abstract

The present application relates to the technical field of aggregation-induced emission materials, in particular to a novel near-infrared two-region aggregation-induced emission molecule, a preparation method and application thereof.The structural formula of the novel near-infrared two-region aggregation-induced emission molecule is: or;wherein R1 is selected from or;R2 is selected from one of -H, -C5H 11 , and -C6H 13 . The novel near-infrared two-region aggregation-induced emission molecule exhibits excellent aggregation-induced emission characteristics, a wide absorption waveband, a large Stokes shift, and excellent photothermal stability;The nanoparticles prepared therefrom have good biocompatibility and water dispersibility. Such molecules and nanoparticles have important application value in the fields of photothermal therapy, biological imaging, tumor diagnosis and treatment, and other biomedical engineering fields.

Description

Technical Field

[0001] This invention relates to the field of aggregation-induced emission materials technology, and in particular to a novel near-infrared II aggregation-induced emission molecule, its preparation method, and its application. Background Technology

[0002] Photothermal therapy (PTT) and bioimaging technology, as non-invasive medical methods, have become research hotspots in the biomedical field due to their advantages such as ease of operation, minimal side effects, and strong targeting in areas such as tumor treatment and disease diagnosis. Aggregation-induced emission molecules (AIEgens), with their significantly enhanced fluorescence in the aggregated state, effectively overcome the "aggregation-induced fluorescence quenching (ACQ)" effect of traditional fluorescent molecules, providing a new solution for the development of phototherapy materials.

[0003] Near-infrared II (1000-1700nm) fluorescent materials have advantages such as strong penetration into deep tissues, low interference from tissue scattering and autofluorescence, and high signal-to-noise ratio. Compared with materials in the visible light region (400-700nm) and the near-infrared I region (700-900nm), they are more suitable for bioimaging and treatment of deep tissues. However, existing near-infrared II aggregation-induced emission materials still have the following technical defects: (1) Insufficient flexibility in molecular structure regulation, making it difficult to simultaneously achieve synergistic optimization of wide absorption, long emission wavelength and high photothermal conversion efficiency; (2) Excessive π-stacking in some molecular aggregation states, resulting in poor photostability and low fluorescence quantum yield; (3) Poor water solubility and biocompatibility, making them prone to aggregation in physiological environments, which limits their application in vivo; (4) Complex synthesis routes, harsh reaction conditions, and low yields, which are not conducive to large-scale production and clinical translation; (5) Insufficient functional specificity for different diagnostic and treatment scenarios, making it difficult to meet the diverse needs of precision medicine.

[0004] Therefore, existing technologies still need improvement and development. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a novel near-infrared II aggregation-induced emission molecule, its preparation method and application, aiming to solve the problem of insufficient flexibility in molecular structure regulation in existing aggregation-induced emission molecules.

[0006] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a novel near-infrared II aggregation-induced emission molecule, the structural formula of which is: or ; Wherein, R1 is selected from or R2 is selected from -H, -C5H 11 and -C6H 13 One of them.

[0007] Optionally, the chemical structure of the novel near-infrared II aggregation-induced emission molecule is one of the following: , , , .

[0008] A second aspect of the present invention provides a method for preparing the above-mentioned novel near-infrared II region aggregation-induced emission molecules, comprising the steps of: […]. Compound A and the catalyst were added to an organic solvent and heated under reflux under inert gas protection to obtain a reaction solution. The reaction solution was then purified to obtain the novel near-infrared II aggregation-induced emission molecule. Compound A is 4,9-dibromo-6,7-diphenyl-benzo[1,2,5]thiadiazo[3,4-g]quinoxaline or 4,7-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazo); R1 is selected from... or R2 is selected from -H, -C5H 11 and -C6H 13 One of them.

[0009] Optionally, the The molar ratio of compound A to compound A is (3-4):1.

[0010] Optionally, the catalyst is selected from one or more of tetra(triphenylphosphine)palladium, tri(dibenzylacetone)dipalladium, and tri-tert-butylphosphine tetrafluoroborate; the organic solvent is anhydrous toluene.

[0011] Optionally, the reaction temperature is 100-130℃ and the reaction time is 6-18h.

[0012] Optionally, the reaction solution is purified to obtain the novel near-infrared II aggregation-induced emission molecule. Specifically, the reaction solution is cooled to room temperature, then saturated potassium fluoride solution is added, followed by extraction with dichloromethane, drying with anhydrous sodium sulfate, concentration under reduced pressure, and purification by silica gel column chromatography to obtain the novel near-infrared II aggregation-induced emission molecule.

[0013] In a third aspect, the present invention provides near-infrared II aggregation-induced emission nanoparticles, the nanoparticles comprising the novel near-infrared II aggregation-induced emission molecules described above and a carrier material coating the novel near-infrared II aggregation-induced emission molecules.

[0014] Optionally, the carrier material includes distearylphosphatidylethanolamine-methoxy polyethylene glycol 2000.

[0015] A fourth aspect of the present invention provides a method for preparing near-infrared II aggregation-induced emission nanoparticles as described above, comprising the following steps: The above-mentioned novel near-infrared II aggregation-induced emission molecules were added to tetrahydrofuran to obtain the first mixture; The first mixture is mixed with a carrier material to obtain a second mixture; The second mixture was subjected to ultrasonic treatment, dialysis, and filtration to obtain the near-infrared II region aggregation-induced emission nanoparticles.

[0016] In a fifth aspect, the present invention provides the use of the novel near-infrared II aggregation-induced emission molecule described above, the novel near-infrared II aggregation-induced emission molecule prepared by the above preparation method, the near-infrared II aggregation-induced emission nanoparticles described above, or the near-infrared II aggregation-induced emission nanoparticles prepared by the above preparation method in the preparation of products for tumor diagnosis and / or treatment.

[0017] Beneficial Effects: This invention provides a novel near-infrared II aggregation-induced emission molecule, its preparation method, and its applications. The near-infrared II aggregation-induced emission molecule adopts a strong push-pull electron structure design (D-A-D), using thiophene and thiophene derivatives as π-bridges to conjugate multi-rotor electron donors (triphenylamine, tetraphenylethylene derivatives, etc.) and strong electron acceptors (DPTQ, BBTD, etc.). Specifically, it includes four types of molecules: DA-DPTQ, HAD-DPTQ, TTH-DPTQ, and TTH-BBTD. These molecules exhibit excellent aggregation-induced emission properties, a wide absorption band (660-850 nm), a large Stokes shift, and excellent photothermal stability. Among them, the TTH-BBTD molecule achieves a photothermal conversion efficiency of up to 36.0%, and exhibits strong absorption and emission characteristics in the near-infrared II region (1000-1700 nm) (maximum emission wavelength up to 1150 nm). Nanoparticles (NPs) prepared by nanoprecipitation exhibit good biocompatibility and water dispersibility, with an average particle size of approximately 100-120 nm, a loading of 52-64 wt%, and a relative fluorescence quantum yield as high as 1.40%. Furthermore, these molecules and nanoparticles have significant application value in biomedical engineering fields such as photothermal therapy, bioimaging, and precision tumor diagnosis and treatment, while also providing new design ideas for the structural regulation and functional optimization of near-infrared II aggregation-induced emission materials. Attached Figure Description

[0018] Figure 1 The above are the synthetic routes of the four AIE molecules obtained in Examples 3 and 4 of this invention.

[0019] Figure 2 These are the basic photophysical properties of the four AIE molecules in Examples 3 and 4 of this invention; wherein (A) is the normalized absorption spectrum of AIE molecules dissolved in THF; (B) is the fluorescence emission spectrum; and (C) is the curve showing the relationship between relative emission intensity (I / I0) and water content (fw).

[0020] Figure 3 These are characterization diagrams of TTH-DPTQ NPs and TTH-BBTD NPs from Example 5 of the present invention, wherein (A) absorption of TTH-DPTQ NPs and TTH-BBTD NPs in THF; (B) fluorescence emission spectrum; (C) concentration-dependent curve of TTH-DPTQ; (D) concentration-dependent curve of TTH-BBTD; (E) particle size distribution of TTH-DPTQ NPs and (F) TTH-BBTD NPs in aqueous solution; (G) TEM images of TTH-DPTQ NPs and (H) TTH-BBTD NPs.

[0021] Figure 4 These are the photothermal performance and photostability characterization diagrams of TTH-BBTDNPs in Example 5 of this invention, wherein (A) the photothermal conversion of TTH-BBTD NPs (100 μm) under irradiation with different laser powers; (B) the photothermal conversion of TTH-BBTD NPs under irradiation with an 808 nm laser (0.8 W·cm⁻¹). -2 (C) Photothermal conversion behavior of TTH-BBTD NPs at different concentrations; (D) Photothermal stability of TTH-BBTD NPs during 5 laser on / off switching cycles; Detailed Implementation

[0022] This invention provides a novel near-infrared II region aggregation-induced emission molecule, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0023] In recent years, aggregation-induced emission (AIE) molecules have shown great potential in the biomedical field due to their enhanced fluorescence in the aggregated state, effectively overcoming the ACQ effect of traditional fluorescent molecules. Near-infrared II (1000-1700nm) materials possess advantages such as strong penetration into deep tissues and high signal-to-noise ratio. Combining AIE properties with near-infrared II emission can lead to the development of high-performance phototherapy materials. This invention synthesizes four near-infrared II aggregation-induced emission molecules through a strong push-pull electron structure design (D-A-D) and prepares corresponding nanoparticles, achieving synergistic optimization of optical properties and biological functions.

[0024] Based on this, embodiments of the present invention provide a novel near-infrared II aggregation-induced emission molecule, the structural formula of which is: or ; Wherein, R1 is selected from or R2 is selected from -H, -C5H 11 and -C6H 13 One of them.

[0025] The near-infrared II region aggregation-induced emission molecules (DA-DPTQ, HAD-DPTQ, TTH-DPTQ, TTH-BBTD) provided by this invention have a distorted conformation, which can effectively suppress the π-stacking effect in the aggregated state and exhibit typical aggregation-induced emission characteristics. They have strong absorption and emission capabilities in the near-infrared II region (1000-1700nm), among which TTH-BBTD has a maximum emission wavelength of up to 1150nm, which significantly improves imaging performance and therapeutic effect, and can meet the needs of deep tissue imaging and treatment.

[0026] This invention employs a "D-A-D" strong push-pull electronic structure design, using thiophene and its derivatives as π-bridges to conjugate multi-rotor electron donors (such as triphenylamine and tetraphenylethylene derivatives) with strong electron acceptors (such as DPTQ and BBTD). In aggregation-induced emission (AIE) molecular design, in addition to controlling energy levels and redshifting spectra, the electron donor must also introduce controllable charge transfer (CT) interactions while ensuring the effective operation of the core AIE mechanism (i.e., intramolecular restricted motion, RIM), thereby constructing high-performance, multifunctional luminescent materials.

[0027] Specifically, in the near-infrared II region aggregation-induced emission molecules provided by this invention, the electron donors typically possess significant steric hindrance. For example, donors with large steric hindrance, such as triphenylamine and tetraphenylethylene derivatives, can form highly distorted molecular conformations. In dilute solutions, the benzene ring within the molecule can rotate freely (non-radiative transition), resulting in weak fluorescence. However, in the aggregated state, this rotation is physically restricted, the non-radiative energy dissipation channel is closed, and the radiative transition (emission) channel is opened. Therefore, the non-planar propeller structure of triphenylamine and tetraphenylethylene derivatives ensures the effective operation of the intramolecular motion restriction mechanism and also ensures efficient luminescence in the aggregated state. Secondly, the donor (D) "pushes" its excess electron density into the conjugated system, and the π-bridge, as a conjugation channel, efficiently "transfers" the donor's electron density to the acceptor. More importantly, the length and strength of the π-bridge can amplify this charge transfer effect. Extending the π-bridge (e.g., increasing the number of thiophene units) can enhance the conjugation of the entire molecule, making the electron push-pull effect between the donor and acceptor stronger, thereby significantly narrowing the molecular band gap and causing a significant redshift in the emission wavelength. The acceptor (A)'s strong electron-pulling ability acts like a pump, "drawing" electrons away, forming a strong intramolecular charge transfer (ICT) state. The strength of this ICT state directly determines the final emission color (degree of redshift) and sensitivity to the environment (e.g., polarity). In the D-π-A "golden triangle," the donor is the power source, the acceptor is the compass, and the π-bridge is the core hub that integrates electron transport, conformational regulation, and steric hindrance support. The synergistic effect of these three factors enables the near-infrared II region aggregation-induced emission molecules provided by this invention to exhibit enhanced fluorescence emission in the aggregated state, and to achieve a shift in absorption and emission wavelengths towards longer wavelengths.

[0028] In some embodiments, the chemical structure of the novel near-infrared II aggregation-induced emission molecule is one of the following: , , , .

[0029] In this embodiment, a strong push-pull electronic structure design, using thiophene and its derivatives as π-bridges, conjugately connects the electron donor and electron acceptor. Specifically, it includes four molecules: DA-DPTQ, HAD-DPTQ, TTH-DPTQ, and TTH-BBTD. The structural design and properties of each molecule are as follows: DA-DPTQ: With diphenylamine-derived structure as electron donor, DPTQ as electron acceptor, and thiophene as π bridge; the molecular absorption peak is located at 850 nm, and the fluorescence emission peak is at 1100 nm. It is a typical ACQ molecule, and its coplanar structure leads to strong intermolecular interactions. HAD-DPTQ: Based on DA-DPTQ, an alkyl chain is introduced at the meta position of thiophene. Through structural isomerization combining backbone twisting and rotor twisting, the strong intermolecular interactions are mitigated, achieving a property transformation from ACQ to AIE. The absorption peak is 660 nm, the emission peak is 975 nm, and the fluorescence intensity of the aggregated state is 12.5 times that of the dispersed state. TTH-DPTQ: It uses a tetraphenylethylene (TPE) derivative as an electron donor, DPTQ as an electron acceptor, and a thiophene derivative as a π-bridge; the free rotation and vibrational properties of the TPE structure promote loose molecular packing, and the twisted conformation enhances the photothermal effect; the absorption peak is 690 nm, the emission peak is 990 nm, and the AIE enhancement factor is 22 times. TTH-BBTD: It uses tetraphenylethylene derivatives as electron donors, BBTD with stronger electron-withdrawing ability as electron acceptors, and thiophene derivatives as π bridges. The BBTD acceptor effectively reduces the molecular HOMO-LUMO band gap and prolongs the absorption and emission wavelengths. The absorption peak is 790nm, the emission peak is 1130nm, the AIE enhancement factor is up to 35 times, and the photothermal conversion efficiency is 36.0%.

[0030] An embodiment of the present invention provides a method for preparing the above-mentioned novel near-infrared II aggregation-induced emission molecules, comprising the steps of: ... Compound A and the catalyst were added to an organic solvent and heated under reflux under inert gas protection to obtain a reaction solution. The reaction solution was then purified to obtain the novel near-infrared II aggregation-induced emission molecule. Compound A is 4,9-dibromo-6,7-diphenyl-benzo[1,2,5]thiadiazo[3,4-g]quinoxaline or 4,7-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazo); R1 is selected from... or R2 is selected from -H, -C5H 11 and -C6H 13 One of them.

[0031] The specific synthesis processes of the above four AIE molecules are as follows: Figure 1 As shown, the preparation method provided by this invention has a simple synthetic route, low cost, and is suitable for large-scale preparation. The prepared near-infrared II region aggregation-induced emission molecules exhibit enhanced fluorescence emission in the aggregated state, achieving a shift in absorption and emission wavelengths towards longer wavelengths. The yield of this preparation method is 47%-63%, with TTH-BBTD having the highest yield (60%) and HAD-DPTQ having the lowest yield (53%).

[0032] In some implementations, the The molar ratio of compound A to compound A is (3-4):1.

[0033] In some preferred embodiments, the The molar ratio of compound A to compound A is 3.3:1.

[0034] In some embodiments, the catalyst is selected from one or more of tetra(triphenylphosphine)palladium, tri(dibenzylacetone)dipalladium, and tri-tert-butylphosphine tetrafluoroborate; the organic solvent is anhydrous toluene (ultra-dry toluene).

[0035] In some preferred embodiments, the catalyst is tetra(triphenylphosphine)palladium, or a combination of tri(dibenzylacetone)dipalladium and tritert-butylphosphine tetrafluoroborate; the amount of catalyst used is 10%-20% of the molar amount of the reaction substrate.

[0036] In some implementations, the reaction temperature is 100-130°C and the reaction time is 6-18 hours.

[0037] In some preferred embodiments, the reaction temperature is 120°C and the reaction time is 12 hours.

[0038] In some embodiments, the reaction solution is purified to obtain the novel near-infrared II aggregation-induced emission molecule. Specifically, this includes: cooling the reaction solution to room temperature, adding a saturated potassium fluoride solution, extracting with dichloromethane, drying with anhydrous sodium sulfate, concentrating under reduced pressure, and then purifying by silica gel column chromatography to obtain the novel near-infrared II aggregation-induced emission molecule.

[0039] In some preferred embodiments, the eluent for column chromatography purification is adjusted according to the polarity of the product; DA-DPTQ uses a hexane / dichloromethane mixed solvent, while HAD-DPTQ, TTH-DPTQ, and TTH-BBTD use a petroleum ether / ethyl acetate mixed solvent.

[0040] An embodiment of the present invention provides a near-infrared II aggregation-induced emission nanoparticle, the nanoparticle comprising the above-mentioned novel near-infrared II aggregation-induced emission molecule and a carrier material coating the novel near-infrared II aggregation-induced emission molecule.

[0041] This invention prepares near-infrared II aggregation-induced emission nanoparticles by nanoprecipitation method, and the nanoparticles have the following characteristics: (1) The carrier DSPE-mPEG2000 has good biocompatibility and amphiphilicity, which can effectively encapsulate hydrophobic aggregation-induced emission molecules and improve their water solubility and dispersibility; (2) The average hydrodynamic diameter of the nanoparticles is 100-120nm, and they are regular spherical under transmission electron microscopy (TEM), with uniform particle size and good dispersibility; (3) The loading of aggregation-induced emission molecules is 52-64wt%, of which TTH-DPTQ loading is 64wt% and TTH-BBTD loading is 52wt%; (4) The absorption and emission wavelengths of the nanoparticles are redshifted compared with the pure molecules. TTH-BBTDNPs have a maximum absorption of 850nm and a maximum emission of 1150nm, with a relative fluorescence quantum yield of 1.40%; (5) The photothermal stability is excellent. After 5 heating / cooling cycles with an 808nm laser, the photothermal conversion efficiency does not decrease significantly.

[0042] In some embodiments, the carrier material includes distearylphosphatidylethanolamine-methoxy polyethylene glycol 2000.

[0043] Embodiments of the present invention provide a method for preparing near-infrared II aggregation-induced emission nanoparticles as described above, comprising the following steps: The above-mentioned novel near-infrared II aggregation-induced emission molecules were added to tetrahydrofuran to obtain the first mixture; The first mixture is mixed with a carrier material to obtain a second mixture; The second mixture was subjected to ultrasonic treatment, dialysis, and filtration to obtain the near-infrared II region aggregation-induced emission nanoparticles.

[0044] The above preparation method is simple, low-cost, and suitable for large-scale preparation. The specific steps of the preparation method include: accurately weighing 1 mg of TTH-DPTQ or TTH-BBTD, dissolving it in 1 mL of tetrahydrofuran, and sonicating it for 5 minutes to obtain a homogeneous molecular solution; Under magnetic stirring (300 rpm), the molecular solution was slowly poured into a solution containing 5 mg DSPE-mPEG. 2000 Add 9 mL of deionized water, keeping the stirring speed uniform to avoid localized high concentrations that could lead to aggregation; A miniature probe ultrasonic instrument was used to continuously sonicate the mixed solution for 2 minutes at 45% output power, so that the mixed solution could form a stable colloidal dispersion system. The ultrasonically purified mixture was transferred to a MWCO3500Da dialysis tube and dialyzed in 500mL of deionized water for 24 hours. The deionized water was changed at 0.5, 1, 2, 3 and 4 hours, for a total of 5-7 water changes, in order to completely remove tetrahydrofuran. After dialysis, the nanoparticle solution was filtered through a 0.45μm syringe filter to remove a small amount of large aggregates. The nanoparticle solution of the required concentration was obtained by centrifugation at 8000 rpm using an ultrafiltration centrifuge tube (MWCO 10kDa) and stored in a 4℃ refrigerator in the dark for later use.

[0045] In some implementations, the ultrasonic treatment power is 40%-50%, and the ultrasonic treatment time is 1-3 minutes. This ultrasonic treatment power and ultrasonic time can ensure the formation of a stable nano-dispersion system.

[0046] In some implementations, the water is changed no less than five times during dialysis to ensure that the residual organic solvent content meets the standards for biomedical applications.

[0047] In some embodiments, the concentration of the concentrated nanoparticle solution can be adjusted according to application requirements; preferably, the concentration used is 50-200 μM.

[0048] The present invention provides the application of the above-described novel near-infrared II aggregation-induced emission molecules, the novel near-infrared II aggregation-induced emission molecules prepared by the above-described preparation method, the above-described near-infrared II aggregation-induced emission nanoparticles, or the near-infrared II aggregation-induced emission nanoparticles prepared by the above-described preparation method in the preparation of products for tumor diagnosis and / or treatment.

[0049] First, this invention also provides the application of the near-infrared II region aggregation-induced emission nanoparticles in the preparation of products for tumor diagnosis and / or treatment. The nanoparticles are preferably TTH-BBTD NPs, which exhibit strong fluorescence emission in the 1000-1500 nm wavelength band, a relative quantum yield of up to 1.40%, and a high signal-to-noise ratio. They can be used for high-resolution imaging of biological tissues or lesions such as blood vessels, lymph nodes, and tumors, with a penetration depth of up to several centimeters.

[0050] Secondly, the near-infrared II region aggregation-induced emission nanoparticles also exhibit excellent photothermal conversion performance, with a conversion efficiency reaching 36.0%. Under 808 nm laser irradiation, the power density is 0.4-1.0 W·cm⁻¹. -2 A 100 μM solution can achieve a temperature rise of 12-50℃. It can effectively ablate tumor cells, and the photothermal effect is concentration- and power-dependent, allowing for precise control of the treatment temperature.

[0051] Because these nanoparticles possess both near-infrared II imaging and photothermal therapy capabilities, they can achieve "imaging-guided precision treatment," which has significant application value in tumor diagnosis, treatment, and efficacy evaluation, and can be used for integrated precision diagnosis and treatment of tumors.

[0052] In addition, these nanoparticles can be further applied to antibacterial materials, wound dressings, and surface modification of medical devices, utilizing their photothermal effect to kill pathogens and reduce the risk of infection.

[0053] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are intended only to illustrate the present invention and not to limit it. 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.

[0054] Example 1 This invention provides a method for preparing an electron donor precursor (taking compound 1 as an example), comprising the following steps: Diphenylamine (0.99 g, 5 mmol), 2-bromothiophene (0.98 g, 6 mmol), Pd2(dba)3 (0.27 g, 0.3 mmol), tri-tert-butylphosphine tetrafluoroborate (0.17 g, 0.6 mmol), sodium tert-butoxide (0.86 g, 9 mmol), and anhydrous toluene (10 mL) were placed into a 15 mL test tube and sealed with a polytetrafluoroethylene cap. The reaction mixture was heated to 120 °C and stirred overnight. After cooling to room temperature, the product was purified by silica gel column chromatography using a hexane / dichloromethane mixture as the eluent to give a colorless oily product 1 (electron donor precursor) in 79% yield.

[0055] Product characterization data:¹H NMR (600MHz, THF-d8) δ 7.22 (s, 1H), 7.08 (dd, J=5.7, 1.3Hz, 1H), 7.07–7.03 (m, 1H), 6.96 (ddd, J=7.4, 4.3, 1.2Hz, 1H), 6.87 (dd, J=5.6, 3.7Hz, 1H), 6.69 (dd, J=3.7, 1.3Hz, 1H); 13 CNMR(151MHz,THF-d8)δ152.28,149.11,129.84,126.58,123.49,123.05,122.58,121.91.

[0056] Example 2 This invention provides a method for preparing a tin oxide intermediate (taking compound 2 as an example), comprising the following steps: nBuLi (1.5 mL, 3.6 mmol, 2.4 M hexane solution) was added dropwise to a THF (15 mL) solution of 0.52 g, 3 mmol of 2-(N,N-diphenylamino)thiophene at -78 °C. After stirring the reaction mixture at -78 °C for 0.5 h, tributyltin chloride (1.27 g, 3.6 mmol) was added to the reaction solution in one step. After stirring the mixture at room temperature for 12 h, the reaction was quenched with saturated KF solution. The mixture was extracted three times with ethyl acetate, and the combined organic phases were dried over anhydrous Na₂SO₄. After solvent removal, the product was used directly in the next reaction step without further purification.

[0057] Example 3 This invention provides a method for preparing a novel near-infrared II aggregation-induced emission molecule (DA-DPTQ), comprising the following steps: Compound 2 (1 mmol), 4,9-dibromo-6,7-diphenyl-[1,2,5]thiadiazole-[3,4-g]quinoxaline (150 mg, 0.3 mmol), tetrakis(triphenylphosphine)palladium (Pd(PPh3)4) (22 mg, 0.03 mmol), and ultra-dry toluene (2 mL) were added to a 5 mL test tube and sealed with a PTFE cap. The reaction mixture was heated to 120 °C and stirred overnight. After cooling, the crude product was quenched with saturated KF solution and extracted with dichloromethane. The combined organic phases were dried over anhydrous Na2SO4 to remove the solvent, and the product was purified by silica gel column chromatography to give a brownish-green solid DA-DPTQ in 63% yield.

[0058] Product characterization data:¹H NMR (600MHz, THF-d8) δ 9.07 (d, J=4.1Hz, 2H), 7.58-7.55 (m, 4H), 7.42-7.39 (m, 8H), 7.38-7.35 (m, 8H), 7.29 (dd, J=6.3, 1.2Hz, 2H), 7.22-7.19 (m, 4H), 7.14 (t, J=7.6Hz, 4H), 6.71 (d, J=4.4Hz, 2H); 13 CNMR(151MHz,THF)δ151.93,151.70,147.60,138.12,133.60,132.85,130.30,129.24,128.81,127.79,127.34,124.40,124.06,119.04,115.42.

[0059] Example 4 This invention provides a method for preparing novel near-infrared II aggregation-induced emission molecules (HAD-DPTQ, TTH-DPTQ, TTH-BBTD). Synthesis of compounds 3, 5, and 6 (electron donor precursors): Following the synthesis method of compound 1 in Example 1, the corresponding electron donor precursors were synthesized from diphenylamine and 2-bromo-4-hexylthiophene, tetraphenylethylene derivatives and substituted thiophenes, respectively, with yields of 75%, 70%, and 80%. Synthesis of compounds 4 and 7 (tin compound intermediates): Following the synthesis method of compound 2 in Example 2, tin compound intermediates were synthesized using the corresponding electron donor precursors as raw materials. The products were directly used in the next reaction without purification. Synthesis of HAD-DPTQ: Following the synthesis method of DA-DPTQ in Example 3, the product was a green solid powder with a yield of 53%. 1HNMR(600MHz,THF-d8)δ7.71(dd,J=8.3,1.3Hz,1H),7.46-7.41(m,1H),7.39-7.31(m,5H),7.11-7.06( m,1H),6.85(s,1H),2.49(t,J=7.7Hz,1H),1.58-1.47(m,1H),1.18-0.90(m,4H),0.68(t,J=7.1Hz,2H); Synthesis of TTH-DPTQ: Following the synthesis method of DA-DPTQ in Example 3, the product was a green solid powder with a yield of 47%. 1 HNMR(600MHz,THF-d8)δ7.59(d,J=7.0Hz,1H),7.28(t,J=7.4Hz,1H),7.16(t,J=7.7Hz,1H),7.11-7.03(m,13H),7.02-6.98(m, 4H),6.95(d,J=8.7Hz,2H),6.73(s,1H),2.40(t,J=7.7Hz,1H),1.47(p,J=7.5Hz,1H),1.08-0.94(m,3H),0.64(t,J=7.1Hz,2H); Synthesis of TTH-BBTD: Following the synthesis method of DA-DPTQ in Example 3, the product was a brownish-green solid powder with a yield of 60%. 1 HNMR(600MHz,THF-d8)δ7.12-7.01(m,1H),7.01-6.98(m,1H),6.97-6.94(m,1H),6.94-6.90 (m,1H),2.55-2.46(m,1H),1.53(p,J=7.5Hz,1H),1.15-1.03(m,1H),0.73(t,J=7.0Hz,1H).

[0060] Example 5 This invention provides a method for preparing near-infrared II aggregation-induced emission nanoparticles (taking TTH-BBTDNPs as an example), which specifically includes the following steps: Weigh 1 mg of TTH-BBTD and dissolve it in 1 mL of THF solution, then pour in a solution containing 5 mg of DSPE-mPEG. 2000The mixture was then dissolved in 9 mL of deionized water. A miniature probe sonicator was used to continuously sonicate the mixture for 2 minutes at 45% output power. The mixture was then transferred to a dialysis tube (MWCO 3500 Da) and dialyzed with deionized water for 24 hours, changing the water 5-7 times at intervals of 0.5, 1, 2, 3, and 4 hours. The final nanoparticle solution was filtered through a 0.45 μm syringe filter before use, and the dialysate was concentrated by ultrafiltration centrifugation and stored at 4°C in the dark.

[0061] The loading of TTH-BBTDNPs was found to be 52 wt%; dynamic light scattering (DLS) analysis showed that its average hydrodynamic diameter was approximately 120 nm; transmission electron microscopy (TEM) observation showed that the nanoparticles had a diameter of approximately 100 nm, were regularly spherical, and had good dispersibility; in THF solution, the maximum absorption peak was 850 nm, the fluorescence emission peak was 1150 nm, and the relative fluorescence quantum yield was 1.40% (with IR-26 as a reference).

[0062] Example 6 The embodiments of the present invention test novel near-infrared II aggregation-induced emission molecules, as detailed below: Photophysical property testing: 1. Solution preparation: Prepare a 10 μM solution of the four molecules using THF.

[0063] 2. UV-Vis absorption spectroscopy: At room temperature, pure THF solvent was first scanned as baseline correction. Then, four molecular solutions were tested sequentially, and their maximum absorption wavelengths (λabs) were recorded as 850 nm, 660 nm, 690 nm, and 790 nm, respectively.

[0064] 3. Fluorescence Emission Spectroscopy Test: At room temperature, the prepared solution was added to a four-sided transparent quartz cuvette. The excitation wavelength was fixed, and the fluorescence emission spectra were scanned and recorded. Four molecules were tested, and their maximum emission wavelengths (λem) were recorded as 1100 nm, 975 nm, 990 nm, and 1130 nm, respectively. This result confirms that they all possess near-infrared II (NIR-II, 1000-1700 nm) emission characteristics.

[0065] 4. AIE Performance Testing: To evaluate their AIE performance, this invention tested the three compounds in environments with different water contents (f... wThe fluorescence emission spectra of THF / water solvent systems were analyzed. A series of test solutions were prepared with water volume fractions (fw) gradually increasing from 0% to 90% (e.g., 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%). The fluorescence emission spectra of each molecule at different water contents were measured sequentially. The excitation wavelength and instrument parameters must be kept completely consistent. The AIE enhancement factor αAIE is usually defined as the ratio of the maximum fluorescence intensity (I90%) in the aggregated state (e.g., fw=90%) to the fluorescence intensity in the pure solution state (I0).

[0066] The results are as follows Figure 2 As shown in Table 1, the optical properties of four molecules—DA-DPTQ, HAD-DPTQ, TTH-DPTQ, and TTH-BBTD—were systematically studied. The UV-Vis absorption spectra of these molecules in THF solution were measured, and typical ICT absorption bands were observed at 660, 690, and 790 nm. Figure 2 (A). Notably, their fluorescence emission spectra in THF solution are located in the range of 900-1400 nm, with a maximum emission peak around 1100 nm, exhibiting typical NIR-II emission characteristics. Figure 2 (B). To evaluate their AIE performance, we tested the three compounds in environments with different water contents (f w The fluorescence intensity (PL) spectra of HAD-DPTQ, TTH-DPTQ, and TTH-BBTD in a THF / water solvent system were analyzed. In the THF / water mixed solvent system, the fluorescence intensity of HAD-DPTQ, TTH-DPTQ, and TTH-BBTD gradually increased with increasing water content, reaching a peak at 90% water content, with AIE enhancement factors of 12.5, 22, and 35 times, respectively. DA-DPTQ exhibited ACQ characteristics. Specifically, their fluorescence intensity decreased to some extent with increasing water content, possibly due to the intramolecular charge transfer effect (TICT) characteristic of distorted conformation. It was observed that the PL intensity reached its peak at 90% water content, indicating that the compounds formed aggregates, firmly revealing their AIE trend. Figure 2 (C). Furthermore, the fluorescence enhancement trend of TTH-BBTD is significantly better than that of HAD-DPTQ and TTH-DPTQ. The fluorescence intensity vector comparison diagram shows that DA-DPTQ does not possess AIE characteristics and is a typical ACQ molecule, mainly due to the coplanar structure of the molecule, which makes it difficult to restrict strong intermolecular interactions. Combining a structural isomerization method that integrates backbone twisting and rotor twisting, this invention improves the planarity of the molecule by introducing an alkyl chain at the meta-position of thiophene, resulting in HAD-DPTQ. Due to the restriction of intramolecular motion (RIM), the fluorescence intensity is enhanced in the aggregated state, exhibiting typical AIE properties.

[0067] Meanwhile, the introduction of tetraphenylethylene derivatives can effectively suppress π-π stacking of molecules in the aggregated state, giving the material superior AIE properties. The use of acceptors such as BBTD can also greatly reduce the band gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the molecule, further extending the absorption and emission wavelengths of the molecule.

[0068] Table 1. Optical properties of AIE molecules

[0069] a The maximum absorption was measured at THF (10 μM); b The maximum emission value was measured using THF (10 μM); c Measured in a THF / water mixture of (1:9).

[0070] Example 7 The embodiments of the present invention test novel near-infrared II aggregation-induced emission molecular nanoparticles, as detailed below: Photothermal performance test: 1. Preparation of nanoparticles (TTH-BBTD NPs) 1 mg of TTH-DPTQ or TTH-BBTD was dissolved in 1 mL of THF solution and then poured into 9 mL of deionized water containing 5 mg of DSPE-mPEG2000. The mixture was then sonicated continuously for 2 minutes at 45% output power using a microprobe sonicator. The mixture was then transferred to a dialysis tube (MWCO 3500 Da) and dialyzed with deionized water for 24 hours, changing the water at 0.5, 1, 2, 3, and 4-hour intervals, for a total of 5-7 water changes. The final nanoparticle solution was filtered through a 0.45 μm syringe filter before use, and the dialysate was concentrated by ultrafiltration centrifugation and stored at 4°C for later use. The final nanoparticle solution was concentrated by ultrafiltration before use. Using a pre-established standard curve, the loadings of TTH-DPTQ and TTH-BBTD NPs in the obtained nanoparticles were determined to be 64 and 52 wt%, respectively. The particle size distribution of nanoparticles and the particle size changes of nanoparticles under different physiological environments (water, PBS, and PBS containing 10% FBS) at 37°C were determined by dynamic light scattering (DLS). Next, the nanoparticles were diluted with water to prepare three different concentration gradients (50, 100, and 200 μM). The diluted nanoparticles were dropped onto a copper grid, and after the solvent was air-dried, the diameter of the nanoparticles was observed using a transmission electron microscope.

[0071] 2. Photothermal heating test Experimental setup: A photothermal testing platform was built, mainly consisting of an 808 nm semiconductor laser (power adjustable), an infrared thermal imager (such as FLIR E75 or Fluke Ti400) for real-time monitoring and recording of solution temperature, and quartz cuvettes or sample bottles.

[0072] 3. Concentration-dependent test: (1) Prepare aqueous solutions of TTH-BBTD NPs at different concentrations (e.g., 0, 20, 40, 60, 80, 100 μM). (2) Take a certain volume (e.g., 1 mL) of the solution and place it in a sample vial. (3) Fix the laser power density (0.8 W / cm²). 2 (4) The solution temperature change was continuously recorded using an infrared thermal imager. The irradiation time continued until the solution temperature reached equilibrium (e.g., 10 minutes), and the final temperature rise (ΔT) was recorded. The results showed that the temperature rise reached 50℃ at a concentration of 100 μM.

[0073] 4. Power dependence test: (1) The concentration of TTH-BBTD NPs was fixed at 100 μM. (2) The laser output power was adjusted so that the power density irradiated on the sample was 0.4, 0.6, 0.8, and 1.0 W / cm², respectively. 2 (3) Repeat the above irradiation and recording steps to record the temperature rise curves at different power levels. The results show that the temperature rise increases from 0.4 W / cm². 2 The temperature increased from 12℃ to 1.0 W / cm². 2 50℃ at that time.

[0074] 5. Photothermal stability test Cyclic testing: Multiple cycles of "laser on / off" cyclic testing were performed on a 100 μM TTH-BBTD NPs solution.

[0075] (1) Laser opening: at 1.0 W / cm 2 (1) Irradiate the solution with a power density until the temperature reaches a stable level and is maintained for a period of time. (2) Laser off: Turn off the laser and allow the solution to cool naturally to room temperature. (3) Repeat the above "heating-cooling" process at least 5 times. Data shows that after 5 cycles, the material still maintains excellent photothermal stability and the maximum temperature does not decrease significantly.

[0076] 6. Calculation of photothermal conversion efficiency (PCE, η) Theoretical basis: Photothermal conversion efficiency (η) refers to the ratio of light energy absorbed by a material to heat energy. It is usually calculated by fitting data from the cooling stage, according to the method of Roper et al.

[0077] The results are shown in Table 2 and Figure 3 As shown Table 3. Relative quantum yield of AIE molecules

[0078] a Relative quantum yield of AIE molecules in THF solution; b Relative quantum yield of nanoparticles in aqueous solution.

[0079] To prepare AIE NPs with biocompatibility and good dispersibility, the amphiphilic copolymer DSPE-PEG was used. 2000 Using MAL as the encapsulation matrix, TTH-DPTQ and TTH-BBTD NPs were directly prepared via nanoprecipitation, achieving encapsulation efficiencies of 64% and 52%, respectively. The absorption and emission of the nanoparticles exhibited corresponding redshifts, with the maximum absorption and emission of TTH-BBTD NPs reaching 850 nm and 1150 nm, respectively. Figure 3 China A Figure 3 (B). Secondly, it can be seen that the concentration of the molecule and the absorbance exhibit a good linear relationship (B). Figure 3 C, Figure 3 (D). Dynamic light scattering (DLS) results showed that the average hydrodynamic diameter of these nanoparticles was approximately 120 nm. Meanwhile, transmission electron microscopy (TEM) measurements showed that the diameters of TTH-DPTQ and TTH-BBTD NPs were approximately 100 nm. To investigate the NIR-II FLI capability of the NPs, we measured the relative fluorescence quantum yield (QY) of the nanoparticles in the NIR-II region (1000–1500 nm) using IR-26 (0.5%) and ICG (0.076%) as references. As shown in Table 2, the QY of TTH-BBTD NPs (1.40%) was slightly higher than that of TTH-DPTQ NPs (0.13%) and HAD-DPTQ NPs (0.09%).

[0080] To evaluate the photostability and photothermal conversion efficiency (PCE) of TTH-BBTD NPs, we measured the temperature rise (ΔT) of TTH-BBTD NPs in aqueous solution under different power densities under 808 nm laser irradiation. Figure 4 As shown, when the laser power increases from 0.4 to 1.0 W·cm 2At that time, the temperature rise (ΔT) of 100 μM TTH-BBTD NPs in aqueous solution increased from 12°C to 50°C, indicating that the photothermal conversion efficiency of TTH-BBTD NPs is highly dependent on the laser power. Similarly, the test results clearly show that the photothermal effect of TTH-BBTD NPs exhibits a significant concentration-dependent temperature change, indicating that heat generation can be well controlled by adjusting the concentration and laser power. Irradiation with an 808 nm laser (0.8 W·cm⁻¹)... -2 After five consecutive heating / cooling cycles, TTH-BBTD NPs maintained excellent photothermal stability. The effect of laser power density was also estimated. The calculated photothermal conversion efficiency (η) of TTH-BBTD NPs is approximately 36.0%. The highly distorted conformation of TPE increases intramolecular motion in the excited state and heat generation under light irradiation.

[0081] In summary, this invention provides a novel near-infrared II aggregation-induced emission molecule, its preparation method, and its applications. The near-infrared II aggregation-induced emission molecule adopts a "DAD" strong push-pull electron structure design, using thiophene and thiophene derivatives as π-bridges to conjugate multi-rotor electron donors (triphenylamine, tetraphenylethylene derivatives, etc.) and strong electron acceptors (DPTQ, BBTD, etc.), specifically including four molecules: DA-DPTQ, HAD-DPTQ, TTH-DPTQ, and TTH-BBTD. These molecules exhibit excellent aggregation-induced emission properties, a wide absorption band (660-850 nm), a large Stokes shift, and excellent photothermal stability. Among them, the TTH-BBTD molecule achieves a photothermal conversion efficiency of up to 36.0%, and exhibits strong absorption and emission properties in the near-infrared II region (1000-1700 nm) (with a maximum emission wavelength of up to 1150 nm). Nanoparticles (NPs) prepared by nanoprecipitation exhibit good biocompatibility and water dispersibility, with an average particle size of approximately 100-120 nm, a loading of 52-64 wt%, and a relative fluorescence quantum yield as high as 1.40%. Furthermore, these molecules and nanoparticles have significant application value in biomedical engineering fields such as photothermal therapy, bioimaging, and precision tumor diagnosis and treatment, while also providing new design ideas for the structural regulation and functional optimization of near-infrared II aggregation-induced emission materials.

[0082] 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. A novel near-infrared II aggregation-induced emission molecule, characterized in that, The structural formula of the novel near-infrared II aggregation-induced emission molecule is: or ; Wherein, R1 is selected from or R2 is selected from -H, -C5H 11 and -C6H 13 One of them.

2. The novel near-infrared II aggregation-induced emission molecule according to claim 1, characterized in that, The chemical structure of the novel near-infrared II aggregation-induced emission molecule is one of the following: , , , .

3. A method for preparing a novel near-infrared II region aggregation-induced emission molecule as described in claim 1 or 2, characterized in that, Including steps: Compound A and the catalyst were added to a solvent and heated under reflux under inert gas protection to obtain a reaction solution. The reaction solution was then purified to obtain the novel near-infrared II aggregation-induced emission molecule. Compound A is 4,9-dibromo-6,7-diphenyl-benzo[1,2,5]thiadiazo[3,4-g]quinoxaline or 4,7-dibromobenzo[1,2-c:4,5-c']bis([1,2,5]thiadiazo); R1 is selected from... or R2 is selected from -H, -C5H 11 and -C6H 13 One of them.

4. The preparation method according to claim 3, characterized in that, The The molar ratio of compound A to compound A is (3-4):1; The catalyst is selected from one or more of tetra(triphenylphosphine)palladium, tri(dibenzylacetone)dipalladium, and tri-tert-butylphosphine tetrafluoroborate; the organic solvent is anhydrous toluene.

5. The preparation method according to claim 3, characterized in that, The reaction temperature is 100-130℃, and the reaction time is 6-18h.

6. The preparation method according to claim 3, characterized in that, The reaction solution was purified to obtain the novel near-infrared II aggregation-induced emission molecule. Specifically, the reaction solution was cooled to room temperature, saturated potassium fluoride solution was added, and the solution was extracted with dichloromethane, dried with anhydrous sodium sulfate, concentrated under reduced pressure, and then purified by silica gel column chromatography to obtain the novel near-infrared II aggregation-induced emission molecule.

7. A near-infrared II region aggregation-induced emission nanoparticle, characterized in that, The nanoparticles comprise the novel near-infrared II aggregation-induced emission molecules as described in claim 1 or 2 and a carrier material that encapsulates the novel near-infrared II aggregation-induced emission molecules.

8. The near-infrared II aggregation-induced emission nanoparticles according to claim 7, characterized in that, The carrier material includes distearylphosphatidylethanolamine-methoxy polyethylene glycol 2000.

9. A method for preparing near-infrared II aggregation-induced emission nanoparticles as described in claim 7 or 8, characterized in that, Includes the following steps: Add the novel near-infrared II aggregation-induced emission molecule as described in claim 1 or 2 to tetrahydrofuran to obtain a first mixture; The first mixture is mixed with a carrier material to obtain a second mixture; The second mixture was subjected to ultrasonic treatment, dialysis, and filtration to obtain the near-infrared II region aggregation-induced emission nanoparticles.

10. The use of the novel near-infrared II aggregation-induced emission molecule of claim 1 or 2, the novel near-infrared II aggregation-induced emission molecule prepared by the preparation method of any one of claims 3-6, the near-infrared II aggregation-induced emission nanoparticle of claim 7 or 8, or the near-infrared II aggregation-induced emission nanoparticle prepared by the preparation method of claim 9 in the preparation of products for tumor diagnosis and / or treatment.

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