Near-infrared fluorescent dye using indoline as electron donor, preparation method and application thereof

Abstract

The application provides a preparation method of a near-infrared fluorescent dye using indoline as an electron donor. The method comprises the following steps: under the action of a palladium catalyst, through a Suzuki coupling, using a 1,4-dioxane:water mixed liquid as a solvent, coupling indoline boronic acid and a halogen-containing acceptor, and performing compound purification after high-temperature reaction. The near-infrared fluorescent dye using indoline as an electron donor has strong electron-donating properties, can realize aggregation-induced emission, can emit near-infrared light, and can improve light stability and molar absorption coefficient, so that a large Stokes shift can be realized, the near-infrared fluorescent dye is used for photothermal therapy, and good photothermal therapy efficiency is achieved.

Description

Technical Field

[0001] This invention relates to the field of fine chemicals, and more specifically, to a method for preparing and applying a near-infrared fluorescent dye. Background Technology

[0002] Near-infrared (NIR) emission has important applications in many fields, such as communications, biomedical sensors, and night vision. Researchers are also developing materials and devices to realize highly efficient near-infrared organic light-emitting devices. The second near-infrared window (NIR-II, 1000-1700 nm) region of luminescent biosensors has attracted widespread attention due to its weak tissue scattering, low autofluorescence, deep tissue penetration, good spatial resolution, and high signal-to-speech ratio.

[0003] Photothermal therapy utilizes light radiation to treat a variety of medical diseases, including tumors. First, under external light source irradiation, typically near-infrared light, the longer wavelength and lower energy photons facilitate deeper penetration into biological tissues. A photosensitizer is excited by the specific wavelength of light and then releases vibrational energy, thereby killing the target cells or tissues. Compared to photodynamic therapy, photothermal therapy does not require oxygen to interact with the target cells or tissues. Its nanoparticles can absorb two or more photons and then convert them into high-energy photons, transforming near-infrared light into visible and UV light. In tumor treatment, photosensitive nanomaterials can convert near-infrared light into heat, which is then applied to specific therapeutic sites.

[0004] Currently, most near-infrared emitting fluorescent dyes often adopt a donor-acceptor-donor (DAD) structure with triphenylamine and carbazole, as shown in Formula V. However, these electron donors often have drawbacks such as low molar absorptivity, weak electron-donating ability, and aggregation fluorescence quenching.

[0005] Summary of the Invention

[0006] To address the aforementioned problems in the prior art, the present invention provides a near-infrared fluorescent dye that uses indoline as an electron donor.

[0007] This invention provides a near-infrared fluorescent dye using indoline as an electron donor, the structural formula of which is shown in Formula I:

[0008]

[0009]

[0010] In Formula I, R is independently selected from H, CH3, Cl-C 11 Any one of the alkyl groups or OMe, CN, CF3, NMe2, NET2, NPh2, Any one of them.

[0011] According to the present invention, further, the Acceptor represents a receptor and is any group in Formula II.

[0012]

[0013] According to the present invention, further, the Acceptor represents a receptor and is any group in Formula III.

[0014]

[0015]

[0016] According to the present invention, further, the Acceptor represents a receptor and is any group in Formula IV.

[0017]

[0018]

[0019] According to the present invention, X is further selected independently from any one of O, S, and Se.

[0020] According to the present invention, further, according to the present invention, R2 and R3 are independently selected from H, C1-C 11 Any one of the alkyl groups.

[0021] According to the present invention, further, R4 is independently selected from CN, OMe, OC1-OC 11 Any one of the alkoxy groups.

[0022] On the other hand, the present invention provides a method for preparing near-infrared fluorescent dyes using indoline as an electron donor.

[0023] This includes coupling borate esters and halogenated acceptors via Suzuki coupling under palladium catalyst and using a 1,4-dioxane:water mixture as a solvent, followed by compound purification after reaction at high temperature.

[0024] On the other hand, the present invention also provides the application of near-infrared fluorescent dyes using indoline as electron donors in in vivo imaging.

[0025] On the other hand, this invention also provides the application of near-infrared fluorescent dyes using indoline as an electron donor in photothermal therapy. Because near-infrared fluorescent dyes using indoline as an electron donor have strong electron-donating properties, they can aggregate to induce luminescence, emit near-infrared light, and exhibit improved photostability and molar absorptivity, achieving large Stokes shifts. Therefore, their application in photothermal therapy demonstrates good photothermal therapy efficiency.

[0026] The present invention discloses a near-infrared fluorescent dye using indoline as an electron donor, the beneficial effects of which are specifically reflected in: using indoline as an electron donor, indoline, as an electron donor with excellent performance, can often increase the molar absorptivity of the dye, causing a red shift in the absorption and emission wavelengths of the dye, while also having aggregation-induced emission properties, so that the synthesized near-infrared fluorescent dye has strong electron donor properties, high photostability, high molar absorptivity, and large Stokes shift. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1 The UV-Vis absorption spectra of compound I-3 (as shown in Formula I) and existing dyes with DA structures (as shown in Formula V) in DMSO solution are shown in Figure 10. -5 mol·L -1 The x-axis represents wavelength (nm), and the y-axis represents absorbance (au).

[0029] Figure 2 The fluorescence spectra of compound I-3 (as shown in Formula I) and existing dyes with DD structures (as shown in Formula V) in DMSO solution are shown in Figure 10. -5 mol·L -1 The horizontal axis represents wavelength (nm), and the vertical axis represents fluorescence intensity (au).

[0030] Figure 3 The fluorescence spectra of compound I-3 of formula I in different ratios of tetrahydrofuran and water are shown in Figure 10. -5 mol·L -1 The horizontal axis represents wavelength (nm), and the vertical axis represents fluorescence intensity (au).

[0031] Figure 4 The fluorescence spectra of compound I-5 of formula I in different ratios of tetrahydrofuran and water are shown in Figure 10. -5 mol·L -1 The horizontal axis represents wavelength (nm), and the vertical axis represents fluorescence intensity (au).

[0032] Figure 5 The fluorescence spectra of compound I-3 of formula I in different solvents are shown in Figure 10. -5 mol·L -1 );

[0033] Figure 6 The photothermal conversion efficiency diagram of compound I-7;

[0034] Figure 7 A comparison of the photothermal temperature rise of compound I-7 and the commercial NIR dye indocyanine green;

[0035] Figure 8 The heating curves of compound I-7 at different concentrations of nanoparticles (power 0.88 W / cm²) are shown. 2 );

[0036] Figure 9 The temperature rise curves of compound I-7 at different concentrations (concentration 100 ug / ml) are shown.

[0037] Figure 10 Photostable test results for compound I-7, two reference compounds, and the commercial NIR dye indocyanine green. Detailed Implementation

[0038] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] The present invention will be further illustrated below through examples, the purpose of which is solely to provide a better understanding of the invention. Therefore, the examples given do not limit the scope of protection of the present invention.

[0040] In a preferred embodiment of the present invention:

[0041] R is independently selected from alkyl groups such as H, CH3, C1-C. 11 Any one of them, and OMe, CN, CF3, NMe2, NET2, NPh2, Any one of them;

[0042] The present invention provides a method for preparing the compound shown in Formula I, the main specific steps of which are:

[0043] Using indoline boronic acid or boronic acid ester as starting material, and in the presence of palladium catalysis and an inorganic base, the reaction solvent was selected as 1,4-dioxane:water = 3:1. The compound shown in Formula I was prepared by the Suzuki reaction, which is a chemiluminescent substrate with near-infrared emission.

[0044] Example 1

[0045] Synthesis of dye I-3:

[0046]

[0047] In a 50 mL round-bottom flask, [4-(4-methylphenyl)-1H,2H,3H,3aH,4H,8bHcyclopentadien-7-yl]boronic acid (294 mg, 1 mmol, compound I-1), 4,7-dibromo-2,1,3-benzothiazole (150 mg, 0.5 mmol, compound I-2), tetrakis(triphenylphosphine)palladium (20 mg, 5% eq), potassium carbonate (300 mg, 3 eq), 1,4-dioxane (30 mL), and 10 mL of deionized water were added. The mixture was reacted under nitrogen protection for 3 hours to obtain a crude product. After extraction and distillation, the crude product was purified by column chromatography (PE:EA = 1:1) to obtain a pure red solid (300 mg, yield 60%, compound I-3).

[0048] 1 H NMR(400MHz,Chloroform-d)δ7.69(d,J=1.9Hz,1H),7.67–7.58(m,3H),7.17( d,J=6.4Hz,3H),7.10(d,J=8.2Hz,3H),6.97(s,1H),4.79(s,1H),3.88(s,1H), 2.27(s,4H),2.09–1.97(m,1H),1.97(s,1H),1.89(ddt,J=10.9,4.6,2.2Hz,2 H),1.75(ddt,J=12.9,10.3,6.3Hz,1H),1.67–1.45(m,2H),1.24–1.15(m,2H).

[0049] Mass spectrometry(ESI-MS,m / z):[M+H] + calcd for C 42 H 39 N4S + 631.2980;

[0050] Found: 631.2875.

[0051] Example 2

[0052] Synthesis of dye I-5:

[0053]

[0054] In a 50 mL round-bottom flask, [4-(4-methylphenyl)-1H,2H,3H,3aH,4H,8bHcyclopentadien-7-yl]boronic acid (294 mg, 1 mmol, compound I-1), 4,9-dibromo-6,7-diphenyl-[1,2,5]thiadiazo[3,4-g]quinoxaline (250 mg, 0.5 mmol, compound I-4), tetraphenylphosphine palladium (20 mg, 5% eq), potassium carbonate (300 mg, 3 eq), 1,4-dioxane (30 mL), and 10 mL of deionized water were added. The mixture was reacted under nitrogen protection for 3 hours to obtain the crude product. After extraction and distillation, the crude product was purified by column chromatography (PE:EA = 1:1) to obtain the pure product as a blue solid (380 mg, yield 60%, compound I-5).

[0055] 1 H NMR(500MHz,Chloroform-d)δ7.72–7.66(m,2H),7.58(dd,J=2.0,0.7Hz,1H),7.48–7.36(m,4H),7.12(d,J=8.2Hz,1H),7.08–7. 02(m,2H),6.97–6.91(m,2H),4.20(q,J=3.8Hz,1H),3.01–2.95(m,1H),2.09–1.86(m,3H),1.81–1.67(m,2H),1.64–1.52(m,1H).

[0056] Mass spectrometry(ESI-MS,m / z):[M+H] + calcd for C 56 H 47 N6S + :835.3577;

[0057] Found: 835.3575.

[0058] Example 3

[0059]

[0060] In a 50 ml round-bottom flask, add [4-(4-methylphenyl)-1H,2H,3H,3aH,4H,8bHcyclopentadien-7-yl]boronic acid (294 mg, 1 mmol, compound I-1), bis[5-bromo-4-(2-ethylhexyl)thiophen-2-yl]-5λ^4,11-disulfide-4,6,10,12-tetraazatricyclo[7.3.0.0^{3,7}]dodecane-1(12), 2,4,5 7,9-hexene (450 mg, 0.5 mmol, compound I-6) and tetra-triphenylphosphine palladium (30 mg, 5% eq), potassium carbonate (300 mg, 3 eq), 1,4-dioxane 30 mL and 10 mL of deionized water were reacted under nitrogen protection for 3 hours to obtain the crude product. After extraction and distillation, the crude product was purified by column chromatography (PE:EA = 1:1) to obtain the pure product as a blue solid (480 mg, yield 63%, compound I-7).

[0061] 1 H NMR(500MHz,Chloroform-d)δ7.67(dd,J=7.7,2.0Hz,0H),7.56(d,J=1.9Hz,1H),7.34–7.27(m,1H),7. 29–7.19(m,1H),7.08–7.02(m,2H),6.97–6.91(m,2H),4.20(q,J=3.8Hz,1H),3.01–2.95(m,1H),2.82–

[0062] 2.66(m,1H),2.66–2.59(m,1H),2.37–2.33(m,2H),2.09–1.86(m,3H),1. 81–1.65(m,3H),1.64–1.46(m,3H),1.40–1.22(m,7H),0.95–0.84(m,6H).

[0063] Mass spectrometry(MALDI-MS,m / z):[M+H]calcd for

[0064] C66H72N6S4:1076.4701;

[0065] Found: 1076.4731.

[0066] Example 4

[0067] UV-Vis absorption spectroscopy: Accurately measure 3 mL of DMSO or other organic solvent (any one of DCM, toluene, THF, DMF, or MeCN) into a 1 cm × 1 cm quartz cuvette and record the baseline. Accurately add 30 μL of the stock solutions of compounds I-3, I-5, and I-7 to the cuvette, shake well, and prepare corresponding working solutions with a concentration of 10 μmol / L. Record the UV-Vis absorption spectra of the corresponding compounds. Similarly, after recording the baseline of the DMSO solution, record the following using a UV-Vis spectrophotometer: Figure 1 The UV-Vis absorption spectrum of the initial working solution is shown.

[0068] Example 5

[0069] Fluorescence emission spectroscopy test: Accurately measure 3 mL of DMSO or other organic solvent (any one of DCM, toluene, THF, DMF, MeCN) into a 1 cm × 1 cm quartz cuvette and record the baseline. Accurately add 30 μL of the stock solutions of compounds I-3, I-5, and I-7 to the cuvette, shake well, and prepare corresponding working solutions with a concentration of 10 μmol / L. Record the fluorescence emission spectra of the corresponding compounds, such as... Figure 5 As shown, the fluorescence emission spectrum of the initial working solution was directly recorded using a fluorescence spectrophotometer.

[0070] Example 6

[0071] Fluorescence quantum yield test: Accurately measure 3 mL of DMSO or other organic solvent (DCM, toluene, THF, DMF, MeCN, etc.) and place it in a 1 cm × 1 cm quartz cuvette. Accurately add 30 μL of the stock solutions of compounds I-3, I-5, and I-7 to the cuvette, shake well, and prepare corresponding working solutions with a concentration of 10 μmol / L. Record the fluorescence quantum yield of the corresponding compounds using a fluorescence spectrophotometer equipped with a calibration integrating sphere. The fluorescence quantum yield of the initial working solution is directly measured using the above instrument.

[0072] Example 7

[0073] Fluorescence emission spectroscopy test: Accurately measure 3 mL of tetrahydrofuran / water mixed solutions with different tetrahydrofuran or DMSO ratios (THF fraction, fT, vol = 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99%) into a 1 cm × 1 cm quartz cuvette. Accurately add 30 μL of the stock solutions of compounds I-3, I-5, and I-7 to the cuvette, shake well, and prepare corresponding working solutions with a concentration of 10 μmol / L. Record the fluorescence emission spectra of the corresponding compounds. Figure 3 and Figure 4As shown, compounds I-3 and I-5 possess excellent aggregation-induced emission properties.

[0074] Example 8

[0075] Photothermal efficiency test:

[0076] like Figures 6-9 As shown, the photothermal conversion performance of nanoparticles is related to their ability to absorb and release energy, and is represented by the photothermal conversion efficiency (η). Generally, laser irradiation with wavelengths near the absorption peak is used, and the temperature change of the solution with irradiation time is observed using a thermal imager: An aqueous solution of compound I-7 (50 μg / mL) was added to a PE transparent centrifuge tube. Different powers (0.88 W / cm²) were used... 2 0.76W / cm 2 0.64W / cm 2 0.5W / cm 2 Irradiate with an 808nm laser, then use an 808nm laser (1W / cm²) 2 Different concentrations (5 μg / mL, 10 μg / mL, 25 μg / mL, 50 μg / mL, 100 μg / mL) of I-7 solution were irradiated. Finally, an 808 nm laser (0.88 W / cm²) was used. 2 The I-7 nanoparticles were irradiated with PE centrifuge tubes containing deionized water. Throughout the process, the temperature change of the I-7 solution under illumination was recorded using a thermal imager, as well as the temperature change during the cooling process of the centrifuge tubes after the light source was turned off. Furthermore, the I-7 nanoparticles exhibited good photothermal stability; the solution temperature remained almost constant throughout five laser on-off cycles. Based on the cooling fitted line, the photothermal conversion efficiency of I-7 was calculated to be 43.1%, higher than that reported in most previous literature.

[0077] Example 9

[0078] Light stability test:

[0079] Photostability is a crucial performance indicator for evaluating dyes in practical applications such as long-term imaging. We evaluated the photostability of dyes by continuously irradiating them with light and then monitoring their fluorescence intensity, using the commercially available dye ICG as a reference dye. Figure 5 As shown, the fluorescence intensity of ICG decreases sharply with increasing illumination time. After approximately 15 minutes of illumination, severe photobleaching occurs in the ICG, indicating its poor photostability. Figure 10 As shown, dye I-7 exhibits excellent photostability.

[0080] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0081] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0082] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A near-infrared fluorescent dye using indoline as an electron donor, characterized in that: Its structural formula is:

2. The method for preparing a near-infrared fluorescent dye using indoline as an electron donor as described in claim 1, characterized in that: In a round-bottom flask, [4-(4-methylphenyl)-1H,2H,3H,3aH,4H,8bH-cyclopentadien-7-yl]boronic acid, 4,7-dibromo-2,1,3-benzothiazole, tetra-triphenylphosphine palladium, potassium carbonate, 1,4-dioxane, and deionized water were added. The mixture was reacted under nitrogen protection for 3 hours to obtain a crude product. After extraction and distillation, the crude product was purified by column chromatography to obtain a pure red solid.

3. The method for preparing a near-infrared fluorescent dye using indoline as an electron donor as described in claim 1, characterized in that: In a round-bottom flask, [4-(4-methylphenyl)-1H,2H,3H,3aH,4H,8bHcyclopentadien-7-yl]boronic acid, 4,9-dibromo-6,7-diphenyl-[1,2,5]thiadiazo[3,4-g]quinoxaline, tetra-triphenylphosphine palladium, potassium carbonate, 1,4-dioxane, and deionized water were added. The mixture was reacted under nitrogen protection for 3 hours to obtain a crude product. After extraction and distillation, the crude product was purified by column chromatography to obtain a pure blue solid.

4. The method for preparing a near-infrared fluorescent dye using indoline as an electron donor as described in claim 1, characterized in that: In a round-bottom flask, [4-(4-methylphenyl)-1H,2H,3H,3aH,4H,8bHcyclopentadien-7-yl]boronic acid was added, along with bis[5-bromo-4-(2-ethylhexyl)thiophen-2-yl]-5λ^4,11-disulfide-4,6,10,12-tetraazatricyclo[7.3.0.0^{3,7}]dodecane-1(12), 2,4,5,7,9-hexene, tetratriphenylphosphine palladium, potassium carbonate, 1,4-dioxane, and deionized water. The mixture was reacted under nitrogen protection for 3 hours to obtain a crude product. After extraction and distillation, the crude product was purified by column chromatography to obtain a pure blue solid.

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