Aggregation-induced emission molecule with high molar extinction coefficient as well as preparation method and application of aggregation-induced emission molecule

Abstract

The invention relates to an aggregation-induced emission molecule with a high molar extinction coefficient and a preparation method and application thereof, and belongs to the technical field of biomedical materials. The chemical structure of the aggregation-induced emission molecule with the high molar extinction coefficient is shown as a formula (I) or a formula (II), and Ar is phenyl or substituted phenyl or phenyl containing heteroatoms. Compared with a monomer structure, the aggregation-induced emission molecule with the high molar extinction coefficient has the advantages that the molar extinction coefficient is increased by 2.3-3.7 times and reaches 6.01-9.54 * 10 < 4 > M <-1 >, and the absorption wavelength red shift is 51-98 nm. Wherein the DTPE-BTO-Dimer 6 has the characteristics that the most reddish absorption of the DTPE-BTO-Dimer 6 is 618nm, and the DTPE-BTO-Dimer 6 shows near-infrared emission. The aggregation-induced emission molecules are prepared into nanoparticles which can be used for near-infrared imaging guided photothermal therapy. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical materials, and particularly relates to an aggregation-induced emission molecule with a high molar extinction coefficient, a preparation method thereof, and an application thereof. Background Art

[0002] Aggregation-induced emission (AIE) molecules have attracted extensive attention from scientists due to their high fluorescence brightness in the aggregated state. At present, many AIE luminogens (AIEgens) have been reported and are used in multiple fields such as fluorescence imaging, fluorescence sensing, optoelectronic devices, etc. However, with the in-depth research, it has been gradually found that the highly distorted molecular structure of AIE makes it generally face the problem of weak absorption ability (i.e., small molar extinction coefficient). This problem directly limits the further application of AIE molecules, such as the excitation power and wavelength of fluorescence imaging and sensing, the energy transfer efficiency of light-emitting devices, etc.

[0003] For this reason, in recent years, scientists have proposed various strategies to improve the absorption ability of AIE molecules. For example, Yang et al. (J. Am. Chem. Soc., 2023, 145, 22776.) synthesized a series of dual-receptor compounds 2TT-2BTD based on receptors such as benzothiadiazole. The results showed that compared with the single-receptor compound 2TT-BTD, the molar extinction coefficient was increased by 1.6 - 2.3 times to 1.77 - 4.29×10 4 M -1 cm -1 , but its absorption wavelength was significantly blue-shifted compared with the single-receptor compound. You et al. (Angew. Chem. Int. Ed., 2024, e202417865.) combined two D-A-D molecules using a pyrene-fused bisphenothiadiazine receptor. The results showed that for a single D-A-D molecule, its molar extinction coefficient did not increase significantly, but the absorption wavelength was significantly red-shifted. In addition, Zhou et al. also reported similar results (ACS Nano., 2024, 18, 25144.). Zhang et al. (Adv. Mater., 2023, 35, 2306616.) introduced pentafluorophenyl-gold(I) onto the asymmetric AIEgen TBTP to enhance the electron-withdrawing ability of the molecule. The results showed that its molar extinction coefficient was increased by 1.8 times to 2.6×10 4 M -1 cm -1 , and the absorption wavelength was slightly red-shifted. Generally speaking, although progress has been made in enhancing the absorption ability of molecules, developing AIE molecules with high molar extinction coefficients is still a huge challenge. Summary of the Invention

[0004] The present invention aims to solve the technical problem that the absorption ability of aggregation-induced emission molecules in the prior art is still relatively weak, and provides an aggregation-induced emission molecule with a high molar extinction coefficient, a preparation method thereof, and an application thereof.

[0005] To solve the above technical problems, the technical solution of the present invention is as follows:

[0006] An aggregation-induced emission molecule with a high molar extinction coefficient, the chemical structure of which is shown in formula (I) or formula (II):

[0007]

[0008] In formula (I) and formula (II), Ar is phenyl, substituted phenyl, or phenyl containing a heteroatom.

[0009] In the above technical solution, preferably, when Ar is substituted phenyl, its substituents are methoxy, halogen, or cyano.

[0010] In the above technical solution, preferably, when Ar is phenyl containing a heteroatom, the heteroatom is an N atom.

[0011] In the above technical solution, more preferably, Ar is selected from one of the following structures:

[0012]

[0013] A preparation method of an aggregation-induced emission molecule with a high molar extinction coefficient, comprising the following steps:

[0014] Based on monomer molecules TPE-BTO or DTPE-BTO, reacting with a π-bridged molecule containing an Ar group to obtain a dimer, that is, an aggregation-induced emission molecule is prepared;

[0015] The structural formulas of TPE-BTO and DTPE-BTO are as follows:

[0016]

[0017] In the above technical solution, when the π-bridged molecule containing an Ar group is benzene or p-methoxybenzene, the monomer molecule TPE-BTO or DTPE-BTO and the π-bridged molecule containing an Ar group are synthesized into a dimer through Suzuki-Miyaura coupling reaction.

[0018] In the above technical solution, when the π-bridged molecule containing an Ar group is p-fluorobenzene, tetrafluorobenzene, p-cyanobenzene, or pyrazine, the monomer molecule TPE-BTO or DTPE-BTO and the π-bridged molecule containing an Ar group are synthesized into a dimer through C-H direct arylation reaction.

[0019] Application of an aggregation-induced emission molecule with a high molar extinction coefficient in biofluorescence imaging or photothermal therapy.

[0020] The beneficial effects of the present invention are as follows:

[0021] (1) The AIE molecule synthesized by the π-bridged dimer strategy in the present invention has a molar extinction coefficient increased by 2.3 - 3.7 times to 6.01 - 9.54×10 4 M -1 cm -1 compared with the monomer molecule, and the absorption wavelength is red-shifted by 51 - 98 nm to 494 - 618 nm.

[0022] (2) The fluorescence emission wavelength of the AIE molecule (such as DTPE-BTO-Dimer 6) in the present invention is 718 nm, which is in the near-infrared region and can be used for bioimaging.

[0023] (3) The photothermal conversion efficiency of the AIE molecule (such as D6 NPs) in the present invention reaches 73%, indicating its excellent photothermal conversion ability. Description of the Drawings

[0024] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0025] Figures 1A - 1G They are the 1H NMR spectra of TPE-BTO, TPE-BTO-Dimer 1 - 6 respectively, Figures 1H - 1N They are the 1H NMR spectra of DTPE-BTO and DTPE-BTO-Dimer 1 - 6 respectively;

[0026] Figure 2 It is the ultraviolet-visible absorption spectrogram of the AIE molecule of the present invention in toluene, where A is TPE-BTO and TPE-BTO-Dimer 1, B is TPE-BTO-Dimer 1–6, C is DTPE-BTO and DTPE-BTO-Dimer 1, D is DTPE-BTO-Dimer 1–6;

[0027] Figure 3 It is the fluorescence emission spectrogram of the AIE molecule of the present invention in toluene, where A is TPE-BTO and TPE-BTO-Dimer 1, B is TPE-BTO-Dimer 1–6, C is DTPE-BTO and DTPE-BTO-Dimer 1, D is DTPE-BTO-Dimer1–6;

[0028] Figure 4 It is the optimized molecular structure and electron orbital arrangement diagram of the AIE molecule of the present invention;

[0029] Figure 5 It is the preparation route and performance characterization diagram of AIE molecule D6 NPs prepared by the present invention. Among them, A is the preparation route of D6 NPs, B is the ultraviolet absorption and fluorescence emission spectra of D6 NPs, C is the particle size and transmission electron microscopy image of D6 NPs, D is the photothermal conversion efficiency diagram of D6 NPs, E is the heating-up picture of D6 NPs, F is the heating-up curve of D6 NPs at different concentrations, G is the heating-up curve of D6 NPs under laser irradiation with different powers, and H is the heating-up and cooling-down cycle curve of D6 NPs;

[0030] Figure 6 It is the in-vivo imaging and photothermal therapy effect diagram of AIE molecule D6 NPs prepared by the present invention. Among them, A is the change of fluorescence signal over time at the tumor location of tumor-bearing mice monitored by near-infrared fluorescence imaging, B is the enrichment of D6 NPs in organs after 24 hours, C is the heating-up situation of tumor-bearing mice monitored by an infrared thermal imager under laser irradiation for different times, D is the change of mice tumors within 15 days, E is the tumor photo after 15 days, F is the change of mice body weight within 15 days, and G is the section of the tumor area of mice after 15 days;

[0031] Figure 7 It is a schematic diagram of designing a molecule through the π-bridged dimer strategy. Detailed implementation manners

[0032] The present invention provides an aggregation-induced emission molecule (AIE molecule) with a high molar extinction coefficient, and its chemical structure is shown in Formula (I) or Formula (II):

[0033]

[0034]

[0035] In Formula (I) and Formula (II), Ar is a phenyl group, a substituted phenyl group, or a phenyl group containing a heteroatom.

[0036] Preferably, when Ar is a substituted phenyl group, its substituents are methoxy groups, halogen atoms, or cyano groups. When Ar is a phenyl group containing a heteroatom, its heteroatom is an N atom.

[0037] More preferably, Ar is selected from one of the following structures:

[0038]

[0039] When Ar is selected from one of the above six structures, the AIE molecule of the present invention is labeled as follows:

[0040]

[0041] A preparation method of an aggregation-induced emission molecule with a high molar extinction coefficient according to the present invention includes the following steps: based on monomer molecules TPE-BTO or DTPE-BTO, reacting with a π-bridged molecule containing an Ar group to obtain a dimer, that is, preparing an aggregation-induced emission molecule;

[0042] The structural formulas of TPE-BTO and DTPE-BTO are as follows:

[0043]

[0044] The twelve aggregation-induced emission molecules with high molar extinction coefficients marked above according to the present invention are prepared based on monomer molecules TPE-BTO and DTPE-BTO.

[0045] In order to improve the molar extinction coefficient of AIE molecules, the present invention adopts a π-bridged dimer strategy. Specifically, two AIE molecules TPE-BTO and DTPE-BTO are selected as monomer structures, and benzene, p-methoxybenzene, p-fluorobenzene, tetrafluorobenzene, p-cyanobenzene, and pyrazine are used as π-bridges to synthesize dimers TPE-BTO-Dimer1–6 and DTPE-BTO-Dimer 1–6.

[0046] It has been found through research that compared with monomer molecules, the absorption ε of the corresponding dimer molecules has increased by 2.3 to 3.7 times to 6.01 to 9.54×104M -1 cm -1 , and the wavelength has a red shift of 51 to 98 nm. Among this series of compounds, DTPE-BTO-Dimer 6 has the most red absorption at 618 nm and shows near-infrared emission. Preparing it into nanoparticles (D6 NPs) can be used for near-infrared imaging-guided photothermal therapy.

[0047] The above TPE-BTO, TPE-BTO-Dimer 1–2, DTPE-BTO, and DTPE-BTO-Dimer 1–2 are synthesized through Suzuki-Miyaura coupling reaction, and TPE-BTO-Dimer 3–6 and DTPE-BTO-Dimer 3–6 are synthesized through C-H direct arylation reaction. The synthesis reaction formulas are shown in Formulas (Ⅲ) and (Ⅳ):

[0048]

[0049]

[0050] The AIE molecules of the present invention are prepared into nanoparticles, and the preparation steps include: adding an amphiphilic organic polymer DSPE-PEG and the AIE molecules of the present invention into a tetrahydrofuran solution according to a weight ratio of 3-20:1, adding distilled water, continuously ultrasonicating for 3-5 min, stirring at room temperature for 8-12 h to remove tetrahydrofuran, purifying by dialysis, filtering through a 0.22 μm filter membrane, and finally concentrating with an ultrafiltration centrifugal tube.

[0051] For technologies not mentioned in the present invention, reference is made to the prior art.

[0052] Example 1: Synthesis of the AIE molecules of the present invention

[0053] Synthesis of TPE-BTO, and the synthesis reaction formula is shown in Formula (Ⅲ);

[0054] Compound 1 (0.040 g, 0.089 mmol) and Compound 2 (0.070 g, 0.105 mmol) were added to a mixed solvent of toluene, ethanol and water (V:V:V = 8:1:1, 20 mL). After deoxygenation, Pd(PPh3)4 (5.8 mg, 0.05 mmol) and K2CO3 (0.029 g, 0.21 mmol) were added. After deoxygenation again, the reaction mixture was refluxed at 80 °C for 6 h. After cooling to room temperature, the filtrate was poured into brine and extracted three times with dichloromethane. Then it was dried over anhydrous MgSO4 and filtered. After the filtrate was concentrated under reduced pressure, it was purified by silica gel column chromatography to obtain 0.026 g (0.030 mmol, 35%) of yellow solid TPE-BTO. The 1H NMR spectrum is shown in Figure 1A . 1 1H NMR (400 MHz, CDCl3): δ 7.55 (d, J = 8.0 Hz, 2H), 7.38 (d, J = 7.0 Hz, 1H), 7.33 (s, 1H), 7.18–6.98 (m, 17H), 6.68 (d, J = 7.1 Hz, 1H), 4.37 (t, J = 6.0 Hz, 4H), 1.86–1.75 (m, 2H), 1.63–1.56 (m, 2H), 1.51–1.41 (m, 5H), 1.39–1.30 (m, 8H), 1.02–0.95 (m, 6H), 0.94–0.86 (m, 6H).

[0055] Synthesis of intermediate compound 3

[0056] Compound 2 (0.300 g, 0.449 mmol) and 1,4-benzenediboronic acid bis(pinacol) ester (0.049 g, 0.15 mmol) were added to a mixed solvent of tetrahydrofuran and water (V:V = 5:1, 24 mL). After deoxygenation, Pd(PPh3)4 (0.052 g, 0.044 mmol) and K2CO3 (0.124 g, 0.898 mmol) were added. After deoxygenation again, the reaction mixture was refluxed at 75 °C for 12 h. After cooling to room temperature, the filtrate was poured into brine and extracted three times with dichloromethane. Then it was dried over anhydrous MgSO4 and filtered. The filtrate was concentrated under reduced pressure and purified by silica gel column chromatography to obtain 0.035 g (0.039 mmol, 20%) of the orange solid intermediate compound 3. 1 1H NMR (400 MHz, CDCl3): δ 7.92 (s, 4H), 7.50 (s, 2H), 7.41 (s, 2H), 4.44–4.38 (m, 8H), 1.90–1.82 (m, 4H), 1.64–1.54 (m, 10H), 1.50–1.47 (m, 4H), 1.43–1.32 (m, 18H), 1.03–0.98 (m, 12H), 0.97–0.92 (m, 12H).

[0057] Synthesis of intermediate compound 4

[0058] The synthesis of intermediate compound 4 was similar to that of intermediate compound 3, using compound 2 and 1,4-dimethoxy-2,5-benzenediboronic acid pinacol ester as starting materials. 1 1H NMR (400 MHz, CDCl3): δ 8.09 (s, 2H), 7.73 (s, 2H), 7.39 (s, 2H), 4.42–4.37 (m, 8H), 4.01 (s, 6H), 1.88–1.81 (m, 4H), 1.67–1.54 (m, 14H), 1.41–1.33 (m, 18H), 1.04–0.98 (m, 12H), 0.95–0.91 (m, 12H).

[0059] Synthesis of TPE-BTO-Dimer 1

[0060] Compound 1 (0.033 g, 0.072 mmol) and intermediate compound 3 (0.030 g, 0.024 mmol) were added to a mixed solvent of tetrahydrofuran and water (V:V = 5:1, 18 mL). After deoxygenation, Pd(PPh3)4 (2.3 mg, 0.002 mmol) and K2CO3 (6.9 mg, 0.050 mmol) were added. After deoxygenation again, the reaction mixture was refluxed at 75 °C for 12 h. After cooling to room temperature, the filtrate was poured into brine and extracted three times with dichloromethane. Then it was dried over anhydrous MgSO4 and filtered. The filtrate was concentrated under reduced pressure and purified by silica gel column chromatography to obtain 0.014 g (0.008 mmol, 33%) of red solid TPE - BTO - Dimer 1. The 1H NMR spectrum is shown in Figure 1B . 1 1H NMR (400 MHz, CDCl3): δ 7.93 (s, 4H), 7.56 (d, J = 8.1 Hz, 4H), 7.51 (s, 2H), 7.36 (s, 2H), 7.17–7.10 (m, 22H), 7.08–7.00 (m, 12H), 4.46–4.39 (m, 8H), 1.91–1.83 (m, 4H), 1.66–1.55 (m, 10H), 1.51–1.46 (m, 4H), 1.45–1.32 (m, 18H), 1.04–0.98 (m, 12H), 0.96–0.89 (m, 12H).

[0061] Synthesis of TPE - BTO - Dimer 2

[0062] The synthesis of TPE - BTO - Dimer 2 was similar to that of TPE - BTO - Dimer 1. Using compound 1 and intermediate compound 4 as raw materials, TPE - BTO - Dimer 2 was synthesized. The 1H NMR spectrum is shown in Figure 1C . 1 1H NMR (400 MHz, CDCl3): δ 8.10 (s, 2H), 7.74 (s, 2H), 7.56 (d, J = 8.0 Hz, 4H), 7.35 (s, 2H), 7.17–7.01 (m, 34H), 4.44–4.38 (m, 8H), 4.01 (s, 6H), 1.91–1.83 (m, 4H), 1.70–1.57 (m, 10H), 1.51–1.46 (m, 4H), 1.44–1.33 (m, 18H), 1.05–0.98 (m, 12H), 0.95–0.89 (m, 12H).

[0063] Synthesis of TPE - BTO - Dimer 3

[0064] Pd2(dba)3 (0.5 mg, 0.5 μmol), P(o-MeOPh)3 (0.3 mg, 0.001 mmol), PivOH (0.3 mg, 0.003 mmol) and Cs2CO3 (8.5 mg, 0.026 mmol) were added to an ultradry toluene solution. After deoxygenation, TPE-BTO (20 mg, 0.024 mmol) and 1,4-dibromo-2,5-difluorobenzene (3.0 mg, 0.011 mmol) were added. After deoxygenation again, the reaction mixture was refluxed at 100 °C for 12 h. After cooling to room temperature, the filtrate was poured into brine and extracted three times with dichloromethane. Then it was dried over anhydrous MgSO4 and filtered. The filtrate was concentrated under reduced pressure and purified by silica gel column chromatography to obtain 15 mg (0.008 mmol, 77%) of the red solid TPE-BTO-Dimer 3. The 1H NMR spectrum is shown in Figure 1D 。 1 1H NMR (400 MHz, CDCl3): δ 8.01–7.85 (m, 4H), 7.57 (d, J = 8.0 Hz, 4H), 7.35 (s, 2H), 7.18–7.00 (m, 34H), 4.47–4.37 (m, 8H), 1.90–1.82 (m, 4H), 1.67–1.55 (m, 10H), 1.50–1.46 (m, 4H), 1.45–1.27 (m, 18H), 1.04–0.97 (m, 12H), 0.96–0.89 (m, 12H).

[0065] Synthesis of TPE-BTO-Dimer 4

[0066] The synthesis of TPE-BTO-Dimer 4 was similar to that of TPE-BTO-Dimer 3. Using TPE-BTO and 1,4-dibromotetrafluorobenzene as raw materials, TPE-BTO-Dimer 4 was synthesized. The 1H NMR spectrum is shown in Figure 1E 。 1 1H NMR (400 MHz, CDCl3): δ 7.75 (s, 2H), 7.56 (d, J = 8.0 Hz, 4H), 7.34 (s, 2H), 7.19–6.99 (m, 34H), 4.46–4.35 (m, 8H), 1.92–1.79 (m, 4H), 1.65–1.54 (m, 10H), 1.49–1.45 (m, 4H), 1.45–1.28 (m, 18H), 1.03–0.89 (m, 24H).

[0067] Synthesis of TPE-BTO-Dimer 5

[0068] The synthesis of TPE-BTO-Dimer 5 is similar to that of TPE-BTO-Dimer 3. Using TPE-BTO and 2,5-dibromoterephthalonitrile as raw materials, TPE-BTO-Dimer 5 was synthesized. See its 1H NMR spectrum in Figure 1F . 1 1H NMR(400MHz,CDCl3):δ8.61(s,2H),8.27(s,2H),7.58(d,J=8.0Hz,4H),7.37(s,2H),7.19–7.00(m,34H),4.54–4.45(m,4H),4.44–4.35(m,4H),1.91–1.83(m,4H),1.67–1.54(m,10H),1.48–1.44(m,4H),1.43–1.28(m,18H),1.04–0.96(m,12H),0.95–0.88(m,12H).

[0069] Synthesis of TPE-BTO-Dimer 6

[0070] The synthesis of TPE-BTO-Dimer 6 is similar to that of TPE-BTO-Dimer 3. Using TPE-BTO and 2,5-dibromopyrazine as raw materials, TPE-BTO-Dimer 6 was synthesized. See its 1H NMR spectrum in Figure 1G . 1 1H NMR(400MHz,CDCl3):δ9.16(s,2H),8.09(s,2H),7.57(d,J=8.1Hz,4H),7.37(s,2H),7.20–6.97(m,34H),4.52–4.45(m,4H),4.44–4.38(m,4H),1.91–1.84(m,4H),1.66–1.57(m,10H),1.51–1.46(m,4H),1.44–1.30(m,18H),1.04–0.91(m,24H).

[0071] Synthesis of DTPE-BTO

[0072] The synthesis of DTPE-BTO is similar to that of TPE-BTO. Using compound 5 and compound 2 as raw materials, DTPE-BTO was synthesized. See its 1H NMR spectrum in Figure 1H . 11H NMR (400 MHz, CDCl3): δ 7.61 (d, J = 8.1 Hz, 2H), 7.38 (d, J = 7.1 Hz, 1H), 7.22 (s, 1H), 7.17–6.90 (m, 37H), 6.85–6.77 (m, 3H), 6.66 (d, J = 7.0 Hz, 1H), 4.43–4.33 (m, 4H), 1.90–1.77 (m, 2H), 1.65–1.54 (m, 4H), 1.51–1.45 (m, 3H), 1.44–1.30 (m, 9H), 1.03–0.90 (m, 12H).

[0073] Synthesis of DTPE - BTO - Dimer 1

[0074] Compound 5 (0.035 g, 0.040 mmol) and compound 3 (0.019 g, 0.015 mmol) were added to a mixed solvent of 1,4 - dioxane and water (V:V = 5:1, 24 mL). After deoxygenation, Pd(PPh3)4 (4.6 mg, 0.004 mmol) and K2CO3 (0.011 g, 0.080 mmol) were added. After deoxygenation again, the reaction mixture was refluxed at 100 °C for 12 h. After cooling to room temperature, the filtrate was poured into brine and extracted three times with dichloromethane. Then it was dried over anhydrous MgSO4 and filtered. The filtrate was concentrated under reduced pressure and purified by silica gel column chromatography to obtain 0.020 g (0.039 mmol, 60%) of deep purple solid DTPE - BTO - Dimer 1. The 1H NMR spectrum is shown in Figure 1I .

[0075] Synthesis of DTPE - BTO - Dimer 2

[0076] The synthesis of DTPE - BTO - Dimer 2 was similar to that of DTPE - BTO - Dimer 1. Using compound 5 and compound 4 as raw materials, DTPE - BTO - Dimer 2 was synthesized. The 1H NMR spectrum is shown in Figure 1J . 1 1H NMR (400 MHz, CDCl3): δ 8.10 (s, 2H), 7.74 (s, 2H), 7.62 (d, J = 8.4 Hz, 4H), 7.23 (s, 2H), 7.14–6.91 (m, 72H), 6.84–6.78 (m, 8H), 4.41 (d, J = 6.1 Hz, 8H), 4.01 (s, 6H), 1.95–1.80 (m, 4H), 1.77–1.56 (m, 12H), 1.52–1.50 (m, 2H), 1.48–1.31 (m, 18H), 1.07–1.00 (m, 12H), 0.97–0.91 (m, 12H).

[0077] Synthesis of DTPE - BTO - Dimer 3

[0078] Pd2(dba)3 (1.2 mg, 0.001 mmol), P(o - MeOPh)3 (0.9 mg, 0.003 mmol), PivOH (0.8 mg, 0.008 mmol) and Cs2CO3 (0.020 g, 0.062 mmol) were added to an ultradry p - xylene solution. After deoxygenation, DTPE - BTO (0.080 g, 0.063 mmol) and 1,4 - dibromo - 2,5 - difluorobenzene (0.007 g, 0.026 mmol) were added. After deoxygenation again, the reaction mixture was refluxed at 100 °C for 12 h. After cooling to room temperature, the filtrate was poured into brine and extracted three times with dichloromethane. Then it was dried over anhydrous MgSO4 and filtered. The filtrate was concentrated under reduced pressure and purified by silica gel column chromatography to obtain 0.036 g (0.014 mmol, 52%) of a dark purple solid DTPE - BTO - Dimer 3. The 1H NMR spectrum is shown in Figure 1K 。 1 H NMR (400 MHz, CDCl3): δ 7.99–7.90 (m, 3H), 7.64–7.59 (m, 3H), 7.23 (s, 2H), 7.16–7.03 (m, 62H), 7.00–6.91 (m, 12H), 6.85–6.79 (m, 8H), 4.50–4.37 (m, 8H), 1.93–1.81 (m, 4H), 1.70–1.56 (m, 10H), 1.52–1.50 (m, 4H), 1.46–1.34 (m, 18H), 1.06–1.00 (m, 12H), 0.98–0.92 (m, 12H).

[0079] Synthesis of DTPE - BTO - Dimer 4

[0080] The synthesis of DTPE - BTO - Dimer 4 is similar to that of DTPE - BTO - Dimer 3. Using DTPE - BTO and 1,4 - dibromotetrafluorobenzene as raw materials, DTPE - BTO - Dimer 4 was synthesized. The 1H NMR spectrum is shown in Figure 1L 。 1HNMR(400MHz, CDCl3): δ 7.80 (s, 2H), 7.63 (d, J = 8.5 Hz, 4H), 7.15–7.03 (m, 64H), 6.99–6.92 (m, 10H), 6.84–6.80 (m, 8H), 4.55–4.45 (m, 4H), 4.43–4.33 (m, 4H), 1.92–1.81 (m, 4H), 1.68–1.53 (m, 14H), 1.43–1.34 (m, 18H), 1.03–0.98 (m, 12H), 0.95–0.91 (m, 12H).

[0081] Synthesis of DTPE - BTO - Dimer 5

[0082] The synthesis of DTPE - BTO - Dimer 5 is similar to that of DTPE - BTO - Dimer 3. Using DTPE - BTO and 2,5 - dibromoterephthalonitrile as raw materials, DTPE - BTO - Dimer 5 is synthesized. The 1H NMR spectrum is shown in Figure 1M . 1 H NMR(400MHz, CDCl3): δ 8.62 (s, 1H), 8.27 (s, 1H), 7.65–7.60 (m, 4H), 7.15–7.04 (m, 64H), 6.98–6.91 (m, 12H), 6.84–6.79 (m, 8H), 4.55–4.36 (m, 8H), 1.92–1.84 (m, 4H), 1.70–1.55 (m, 14H), 1.43–1.35 (m, 18H), 1.06–0.99 (m, 12H), 0.96–0.91 (m, 12H).

[0083] Synthesis of DTPE - BTO - Dimer 6

[0084] The synthesis of DTPE - BTO - Dimer 6 is similar to that of DTPE - BTO - Dimer 3. Using DTPE - BTO and 2,5 - dibromopyrazine as raw materials, DTPE - BTO - Dimer 6 is synthesized. The 1H NMR spectrum is shown in Figure 1N . 11H NMR (400 MHz, CDCl3): δ 9.16 (s, 2H), 8.09 (s, 2H), 7.63 (d, J = 8.3 Hz, 4H), 7.15–7.03 (m, 62H), 7.00–6.91 (m, 12H), 6.86–6.76 (m, 8H), 4.52–4.38 (m, 8H), 1.94–1.83 (m, 4H), 1.70–1.49 (m, 10H), 1.49–1.45 (m, 8H), 1.44–1.36 (m, 14H), 1.06–1.00 (m, 12H), 0.99–0.93 (m, 12H).

[0085] Example 2:

[0086] The AIE molecules prepared in Example 1 were separately placed in toluene for spectral measurement, and the results are as follows:

[0087] As Figure 2 shown in 4 A, the absorption peak of TPE-BTO is 449 nm, and the molar extinction coefficient is 2.69×10 -1 M 4 −1 - 1 cm -1 −1 Figure 2 Figure 2 4 M -1 cm -1 −1 4 M -1 cm -1 ( Figure 2 C), the absorption peaks of DTPE-BTO-Dimer 1–6 are redshifted to 572–618 nm respectively, and the molar extinction coefficients are enhanced to 6.01–9.54×10 4 M -1 cm -1 ( Figure 2 D). Considering that the molar extinction coefficients of existing AIE molecules are in the range of 2–5×104 M -1 cm -1 In the present invention, the concentration of the dimer molecule reaches 6.01 - 9.54×10 4 M -1 cm -1 , indicating that the π-bridged dimer strategy can significantly improve the absorption ability of AIE molecules.

[0088] The luminescence properties of AIE molecules in toluene were further studied ( Figure 3 ). The emission peak of TPE-BTO is 568 nm, and the fluorescence quantum yield is 58%. For TPE-BTO-Dimer 1–6, their fluorescence emission peaks are at 572 - 622 nm, and good luminescence efficiency is maintained, which is 22 - 84%. In addition, there are obvious shoulders in the emission spectra of TPE-BTO-Dimer 1–6, which may be due to the formation of local excited states during the excitation process of the molecules. The emission peak of DTPE-BTO is 648 nm, and the fluorescence quantum yield is 49%. For DTPE-BTO-Dimer 1–6, their fluorescence emission peaks are redshifted to 656 - 718 nm respectively, and strong luminescence efficiency is also maintained, which is 21 - 69%.

[0089] Example 3: Theoretical Calculation of AIE Molecules

[0090] To further understand the photophysical properties of the AIE molecules prepared in Example 1, taking TPE-BTO and TPE-BTO-Dimer 1 series compounds as examples, DFT theoretical calculations were carried out using the Gaussian16 program, and the optimal structures and corresponding electronic orbital distributions in the ground state were calculated at the B3LYP / 6-31G** level. To reduce the computational amount, the alkyl chains were removed during the calculation of all compounds. As Figure 4 shown, the angle between the dimer molecule acceptor and the π-bridge is extremely small (<1°), almost negligible, enabling the acceptor and the π-bridge to form a large conjugated plane, thus allowing electrons to be effectively delocalized. The calculated results of the chemical oscillator strengths of the two series show that the oscillator strength of TPE-BTO is 0.47, and the oscillator strength of TPE-BTO-Dimer 1 is increased to 1.97, indicating that the π-bridged dimer strategy effectively improves the oscillator strength and causes a large molar extinction coefficient. In addition, the theoretical calculation shows that the absorption wavelengths of the dimer molecules have a significant redshift compared to the monomers. Specifically, the absorption wavelength of TPE-BTO is 545 nm, and that of TPE-BTO-Dimer 1 is redshifted to 629 nm, which is basically consistent with the conclusion obtained from the test in Example 2.

[0091] Example 4: Preparation and Performance Testing of D6 NPs

[0092] The biocompatible amphiphilic copolymer DSPE-PEG 2000 and the AIE molecule DTPE-BTO-Dimer 6 of the present invention were added to a tetrahydrofuran solution at a weight ratio of 10:1, distilled water was added, and ultrasonic treatment was carried out continuously for 5 min, followed by stirring at room temperature for 10 h to remove tetrahydrofuran. After purification by dialysis, filtration was carried out through a 0.22 μm filter membrane, and finally concentration was carried out using an ultrafiltration centrifugal tube to obtain nanoparticles D6 NPs.

[0093] Among the two series of compounds, DTPE-BTO-Dimer 6 has the reddest absorption wavelength of 618 nm and shows near-infrared emission at 718 nm. Based on its good photophysical properties, it was used for photothermal therapy. The biocompatible amphiphilic copolymer DSPE-PEG 2000 was used to encapsulate DTPE-BTO-Dimer 6, and composite D6 NPs were prepared by the nanoprecipitation method ( Figure 5 A). The absorption peak of D6 NPs is 600 nm, and the emission wavelength peak is located in the near-infrared region at 799 nm ( Figure 5 B). The results of dynamic light scattering tests show that the average diameter of these D6 NPs is 64.8 nm, and the polydispersity index is 0.131 ( Figure 5 C). Transmission electron microscopy images show that these D6 NPs exhibit a uniform spherical morphology with an average diameter of about 50 nm. The appropriate size enables these D6 NPs to passively accumulate at the tumor site through the enhanced permeability and retention effect. Subsequently, when irradiated with a 655 nm laser (0.8 W / cm 2 ²) for 10 min, D6 NPs reached a stable temperature at 60 °C and a concentration of 100 μM, and the photothermal conversion efficiency (PCE) of D6 NPs was determined to be 73% ( Figure 5 D,E), indicating its excellent light absorption ability. In addition, it was also verified that D6 NPs have the characteristic of temperature increase related to concentration and laser power density ( Figure 5 F,G). These results indicate that the heat generated from D6 NPs can be regulated. Additionally, under 655 nm laser irradiation, after five consecutive heating-cooling processes, D� NPs also maintained excellent photothermal generation ability ( Figure 5 H). These results indicate that D6 NPs are excellent photothermal therapy reagents with great potential.

[0094] Example 5: In vivo imaging and photothermal therapy

[0095] The near-infrared imaging and accumulation ability at the tumor site of D6 NPs prepared in Example 4 were preliminarily estimated. Before injecting D6 NPs, the mice showed extremely weak autofluorescence interference on the LP filter at 840 nm ( Figure 6A). After tail vein injection of D6 NPs, over time, the fluorescence signal gradually appeared and increased in the tumor region, indicating good tumor site accumulation ability. Among them, the fluorescence intensity reached the maximum at 10 h after injection and then decreased due to metabolism. To quantitatively analyze the biodistribution of D6 NPs 24 h after injection, the tumor tissue and major organs were isolated. As Figure 6 shown in B, it can be confirmed that there is an obvious fluorescence signal in the tumor region, and at the same time, the fluorescence emission of the liver and spleen can also be seen. This is consistent with the results of near-infrared imaging. Based on the strong photothermal conversion efficiency of D6 NPs, 10 h after intravenous administration, a 655 nm laser (0.6 W / cm 2 ) was used as the near-infrared laser light source for in vivo photothermal imaging experiments. According to Figure 6 the infrared thermography shown in C, after irradiation for 8 min, the temperature plateau at the tumor site was about 58 °C. In contrast, under the same conditions, the temperature increase of the PBS-treated mice was negligible, further proving that D6 NPs have reliable photothermal conversion performance.

[0096] Subsequently, the 4T1 tumor-bearing mice were randomly divided into 4 groups to evaluate the in vivo antitumor effect of D6 NPs. Only D6 NPs were intravenously injected once, and laser irradiation (655 nm, 0.6 W / cm 2 , 8 min) was performed once 10 h after injection. The growth of solid tumors in the D6 NPs plus laser irradiation phototherapy group was completely inhibited, and the tumor almost disappeared on the 3rd day. After 15 days of treatment, tumor eradication was achieved. The tumor volumes of the other three groups (PBS, PBS+L, D6 NPs alone) increased rapidly and had no inhibitory effect on tumor growth( Figure 6 D, E). During the whole treatment process, the body weights of the four groups of mice increased slightly( Figure 6 F). On the other hand, the in vivo treatment mechanism of D6 NPs was verified by histological analysis of tumor sections. As Figure 6 shown in G, compared with the other three groups, there were more massive nuclear deletions and vacuolizations in the tumor tissue of the D6 NPs laser group, indicating severe apoptosis or necrosis of cancer cells. TUNEL staining confirmed that severe apoptosis or necrosis occurred in the 4TI cells treated with laser irradiation. At the same time, after D6 NPs plus laser irradiation, the inhibition of cell proliferation was further confirmed by Ki67 staining. Generally speaking, these experimental results indicate that D6 NPs are effective near-infrared imaging-guided photothermal therapy reagents.

[0097] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. An aggregation-induced emission molecule with a high molar extinction coefficient, characterized in that, Its chemical structure is shown in formula (I) or formula (II): In formula (I) and formula (II), Ar is phenyl, substituted phenyl or phenyl containing heteroatoms.

2. The aggregation-induced emission molecule with a high molar extinction coefficient according to claim 1, characterized in that, When Ar is substituted phenyl, its substituents are methoxy, halogen or cyano.

3. The aggregation-induced emission molecule with a high molar extinction coefficient according to claim 1, characterized in that, When Ar is phenyl containing heteroatoms, its heteroatom is N atom.

4. The aggregation-induced emission molecule with a high molar extinction coefficient according to claim 1, characterized in that, Ar is selected from one of the following structures:

5. A method for preparing an aggregation-induced emission molecule with a high molar extinction coefficient according to claim 1, characterized in that, It includes the following steps: Based on monomer molecules TPE-BTO or DTPE-BTO, reacting with π-bridged molecules containing Ar groups to obtain dimers, that is, preparing aggregation-induced emission molecules; The structural formulas of TPE-BTO and DTPE-BTO are as follows respectively:

6. The preparation method of the aggregation-induced emission molecule with a high molar extinction coefficient according to claim 5, characterized in that, When the π-bridged molecule containing Ar group is benzene or p-methoxybenzene, the monomer molecule TPE-BTO or DTPE-BTO and the π-bridged molecule containing Ar group are synthesized into dimers through Suzuki-Miyaura coupling reaction.

7. The preparation method of the aggregation-induced emission molecule with a high molar extinction coefficient according to claim 5, characterized in that, When the π-bridged molecule containing Ar group is p-fluorobenzene, tetrafluorobenzene, p-cyanobenzene or pyrazine, the monomer molecule TPE-BTO or DTPE-BTO and the π-bridged molecule containing Ar group are synthesized into dimers through C-H direct arylation reaction.

8. Use of the aggregation-induced emission molecule with high molar extinction coefficient according to any one of claims 1-4 or the aggregation-induced emission molecule with high molar extinction coefficient prepared by the preparation method according to any one of claims 5-7 in biofluorescence imaging or photothermal therapy.

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