Preparation and application of ionic near-infrared luminescent material

Abstract

The invention discloses preparation and application of a D-pi-A ionic near-infrared luminescent material, and the near-infrared luminescent material is constructed on the basis of a strong electron withdrawing group 3-(2-methylquinoline-1-yl) propane-1-sulfonic acid inner salt by taking 2-vinyl thiophene as a pi bridge and three strong electron donating groups. The D-pi-A type near-infrared molecules have the following structures I, II and III: 3-(2-methylquinoline-1-yl) propane-1-sulfonic acid inner salt is used as an electron withdrawing group, 2-vinyl thiophene is used as a pi bridge to be connected with various donors, and two D-pi-A type near-infrared molecules are designed and synthesized. According to the present invention, the 3-(2-methylquinoline-1-yl) propane-1-sulfonic acid inner salt has strong electron withdrawing ability, can achieve low LUMO energy level, and can form strong pi accumulation so as to obtain high electron mobility; when the electron-deficient acceptor (A) is connected to the electron-rich donor (D), an electron push-pull effect occurs, resulting in strong charge transfer inside the molecule having a D-A configuration. This transfer facilitates the narrowing of [delta] EST. For such molecules, stronger D or A is more conducive to enhancing the ICT process, effectively promoting wavelength redshift.

Description

Technical Field

[0001] This invention belongs to the field of organic optoelectronic materials and their biomedical applications, and specifically relates to a method for preparing a class of D-π-A ion-type near-infrared aggregation-induced emission materials. Background Technology

[0002] Near-infrared (NIR) luminescent materials are functional optoelectronic materials whose emission wavelengths are in the 650 nm to 1700 nm band. Due to their unique tissue penetration, low scattering, and minimal autofluorescence interference, they demonstrate significant application value in fields such as biomedical imaging, infrared detection, optical communication, and security monitoring. Particularly in the biomedical field, NIR luminescent materials can effectively avoid the strong absorption and scattering of visible light by biological tissues, thereby enabling highly sensitive detection and high-resolution imaging of deep tissues.

[0003] However, traditional organic near-infrared luminescent materials often suffer from poor water solubility, low fluorescence quantum efficiency, and poor biocompatibility, severely limiting their practical application in aqueous environments. To address these issues, researchers have introduced ionic groups (such as sulfonic acid groups, quaternary ammonium salts, and carboxyl groups) into the molecular design to improve the water solubility and biocompatibility of the materials. Ionic near-infrared luminescent materials, by introducing polar functional groups into their molecular framework, possess excellent hydrophilicity and ionization properties, enabling them to be stably dispersed in aqueous environments and well-compatible with biological systems. Furthermore, the ionic groups can specifically interact with target molecules or biological ligands, offering possibilities for targeted diagnostics and other biological applications.

[0004] In recent years, significant progress has been made in the application research of ionic near-infrared luminescent materials in fields such as fluorescent probes, disease diagnosis, photodynamic therapy, and optical sensing. For example, ionic dyes, after binding with targeting ligands, can selectively accumulate at tumor sites, enabling precise bioimaging and treatment. Some ionic near-infrared luminescent materials also possess excellent chemical and photostable stability, maintaining stable fluorescence performance even in complex biological environments, meeting the needs of clinical applications. Therefore, the development of novel, high-performance, and easily modifiable ionic near-infrared luminescent materials has become a research hotspot and important development direction in the field of optoelectronic functional materials. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to design and synthesize a class of near-infrared AIE materials and provide a simple and efficient method for preparing ionic near-infrared AIE materials, so that the materials have better biocompatibility and cell membrane permeability.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a near-infrared AIE material based on 3-(2-methylquinoline-1-yl)propane-1-sulfonic acid inner salt and triphenylamine derivative, and its application, wherein the preparation method includes the following steps:

[0007] Synthesize intermediates and prepare key intermediates of the target framework through Suzuki or Stille coupling reactions; couple the intermediates with specific ionic groups to introduce ionic groups and obtain the target ionic material; purify the obtained target material by column chromatography.

[0008] The structure is as follows:

[0009]

[0010] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0011] 1. This invention is based on the combination of 3-(2-methylquinoline-1-yl)propane-1-sulfonic acid inner salt and triphenylamine derivative, with 2-vinylthiophene as a π bridge, and utilizes mechanisms such as enhancing conjugated chain length and replacing donors to prepare near-infrared luminescent materials.

[0012] 2. The ion-type acceptor provided by this invention has strong electron-withdrawing ability and good water solubility, and is suitable for fields such as bioimaging.

[0013] 3. The near-infrared AIE luminescent material provided by this invention can overcome the ACQ effect of traditional luminescent materials. It generates effective radiative emission through ICT (Inductively Coupled Light) action, thereby improving luminescent efficiency and providing a new approach for the design and development of high-performance AIE materials.

[0014] 4. The method for synthesizing the D-π-A ion-type near-infrared luminescent material provided by this invention is simple and the raw materials are readily available. Attached Figure Description

[0015] Figure 1 The absorption spectra of TT-ATS, BTT-ATS, and BTS-ATS in THF are shown.

[0016] Figure 2 Emission spectra of TT-ATS, BTT-ATS, and BTS-ATS in THF;

[0017] Figure 3 The NMR spectrum of TT-ATS;

[0018] Figure 4 BTT-ATS NMR spectrum;

[0019] Figure 5 BTS-ATS NMR spectrum; Detailed Implementation

[0020] The present invention will now be described in further detail with reference to embodiments and accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby providing a clearer definition of the scope of protection of the present invention. The embodiments described herein are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Example 1: Preparation of D-π-A ionic near-infrared luminescent material TT-ATS: The synthesis route is as follows:

[0022]

[0023] TT-ATS: Under a nitrogen atmosphere, 5-aldehyde-2-bromothiophene (0.50 g, 1.34 mmol), triphenylamine 4-borate (0.81 g, 2.59 mmol), tetrakis(triphenylphosphine)palladium (0.115 g, 0.10 mmol), and potassium carbonate (0.62 g, 4.50 mmol) were added to 20 mL of a 1:1 mixture of THF and water. The reaction was carried out at 90 °C for 12 h. After cooling to room temperature, the solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography. A yellow solid was obtained in 68.8% yield (0.82 g). 20 mL of ethanol was added to a two-necked flask, followed by 0.20 g of the product from the previous step, 0.2 g of 2,3-(2-methylquinoline-1-yl)propane-1-sulfonic acid inner salt (1.02 mmol), and 0.020 g of ammonium acetate (0.05 mmol). The mixture was reacted at 70 °C for 24 h. After cooling to room temperature, the solvent was evaporated under reduced pressure. The product was separated by column chromatography and recrystallized. The product was filtered to obtain a dark purple solid (0.18 g) with a yield of 67.8%.

[0024] The structural characterization data of the obtained product are shown below:

[0025] 1H NMR (500 MHz, CDCl3) δ 8.93 (d, J = 10 Hz, 1H), 8.65 (d, J = 10Hz, 1H), 8.58 (d, J = 10 Hz, 1H), 8.49 (d, J = 15 Hz, 1H), 8.29 (d, J = 10Hz, 1H), 8.23 ​​(d, J = 5.0 Hz, 1H), 8.13 (t, J = 20 Hz, 1H), 7.90 (t, J = 20Hz, 2H), 7.70–7.64 (m, 3H), 7.39–7.31 (m, 6H), 7.15–7.00 (m, 15H), 5.25 (s,2H).

[0026] Example 2: Preparation of D-π-A ionic near-infrared luminescent material BTT-ATS. The synthetic route is as follows:

[0027]

[0028] BTT-ATS: Under a nitrogen atmosphere, 4,5-dibromothiophene-2-carboxaldehyde (0.50 g, 1.87 mmol), triphenylamine 4-borate (0.81 g, 2.59 mmol), tetrakis(triphenylphosphine)palladium (0.115 g, 0.10 mmol), and potassium carbonate (0.62 g, 4.50 mmol) were added to 20 mL of a 1:1 mixture of THF and water. The reaction was carried out at 90 °C for 12 h. After cooling to room temperature, the solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography. A yellow solid was given in 58.2% yield (0.92 g). 20 mL of ethanol was added to a two-necked flask, followed by 0.20 g of the product from the previous step, 0.2 g of 3,3-(2-methylquinoline-1-yl)propane-1-sulfonic acid inner salt (1.02 mmol), and 0.020 g of ammonium acetate (0.05 mmol). The mixture was reacted at 70 °C for 24 h. After cooling to room temperature, the solvent was evaporated under reduced pressure. The product was separated by column chromatography and recrystallized. The product was filtered to obtain a dark purple solid (0.18 g) with a yield of 65.3%.

[0029] The structural characterization data of the obtained product are shown below:

[0030] 1H NMR (500 MHz, CDCl3) δ 8.93 (d, J = 10 Hz, 1H), 8.65 (d, J = 10Hz, 1H), 8.59 (d, J = 10 Hz, 1H), 8.49 (d, J = 15 Hz, 1H), 8.30 (d, J = 10Hz, 1H), 8.23 ​​(d, J = 5.0 Hz, 1H), 8.14 (t, J = 20 Hz, 1H), 7.91 (t, J = 20Hz, 2H), 7.70–7.66 (m, 3H), 7.39–7.36 (m, 6H), 7.12–7.00 (m, 15H), 5.25 (s,2H).

[0031] Example 3: Preparation of D-π-A ionic near-infrared luminescent material BTT-ATS. The synthetic route is as follows:

[0032]

[0033] BTS-ATS: Under a nitrogen atmosphere, a mixture of N,N,N-triphenyl-1,4-phenylenediamine (0.5 g, 1.48 mmol), p-bromoiodobenzene (0.42 g, 1.5 mmol), sodium tert-butoxide (0.42 g, 4.4 mmol), Pd(dba)₂ (0.013 g, 0.148 mmol), and 1,1'-bis(diphenylphosphine)ferrocene (0.0375 g, 7.4 mmol) was added to a 125 mL double-necked flask. Subsequently, 40 mL of toluene was injected into the flask, and the reaction mixture was refluxed for 12 h. After cooling to room temperature, the mixture was filtered to remove insoluble impurities. The mixture was then poured into water and extracted three times with dichloromethane. The combined organic layers were washed successively with saturated sodium bicarbonate and water, and then dried over anhydrous magnesium sulfate. After filtration, the solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography. The obtained product (0.5 g, 1 mmol), 2,5-aldehyde-2-thiopheneboronic acid (0.325 g, 2 mmol), tetrakis(triphenylphosphine)palladium (0.125 g, 1 mmol), and potassium carbonate (0.62 g, 4.5 mmol) were added to 20 mL of a 1:1 mixture of THF and water under a nitrogen atmosphere. The reaction was carried out at 90 °C for 12 h. After cooling to room temperature, the solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography. An orange-yellow solid (7) was given in 55.7% yield (0.46 g). 20 mL of chloroform was added to a two-necked flask, followed by 0.2 g of the product from the previous step and 0.2 g of 3,3-(2-methylquinoline-1-yl)propane-1-sulfonic acid inner salt (1.02 mmol). The mixture was reacted at 70 °C for 24 h. After cooling to room temperature, the solvent was evaporated under reduced pressure. The product was separated by column chromatography and recrystallized. The product was filtered to obtain a dark purple solid (0.15 g) with a yield of 47.2%.

[0034] The structural characterization data of the obtained product are shown below:

[0035] 1 H NMR (500 MHz, CDCl3) δ 9.02 (d, J = 10 Hz, 1H), 8.70 (d, J = 10Hz, 1H), 8.57 (d, J = 10 Hz, 1H), 8.52 (d, J = 15 Hz, 1H), 8.40–8.20 (m, 2H), 8.02 (d, J = 5.0 Hz, 1H), 8.17 (t, J = 20 Hz, 1H), 8.02 (d, J = 5.0 Hz, 1H), 7.65 (d, J = 5.0 Hz, 1H), 7.43–7.00 (m, 10H), 5.28 (s, 1H).

[0036] Example 4: UV-Vis absorption spectra of TT-ATS, BTT-ATS, and BTS-ATS

[0037] Figure 1 The UV-Vis absorption spectra of TT-ATS, BTT-ATS, and BTS-ATS in tetrahydrofuran (THF) solution were measured to investigate their optical absorption characteristics. The maximum absorption wavelength of TT-ATS in THF solution was 520 nm, that of BTT-ATS was 525 nm, and that of BTS-ATS was 560 nm.

[0038] Example 5: Emission spectra of TT-ATS, BTT-ATS, and BTS-ATS

[0039] Figure 2 for Figure 2 The emission spectra of the D-π-A ion-type near-infrared luminescent materials TT-ATS, BTT-ATS, and BTS-ATS obtained in Examples 1 and 2 in THF at room temperature are shown. The maximum emission spectrum of TT-ATS in THF solution is 800 nm, the maximum absorption spectrum of BTT-ATS in THF solution is 805 nm, and the maximum absorption wavelength of BTS-ATS is 820 nm. Compared with TT-ATS, BTS-ATS exhibits a 20 nm redshift in emission, which may be due to the stronger electron-donating ability of BTS-ATS, similar to triphenylamine, compared to the triphenylamine group in TT-ATS.

Claims

1. Preparation and application of a class of D-π-A ionic near-infrared luminescent materials, characterized in that, The characteristic structure of this molecule is shown in I-III below: 。 2. The preparation and application of a type of D-π-A ionic near-infrared luminescent material according to claim 1, characterized in that, Near-infrared luminescent materials were prepared by using 3-(2-methylquinoline-1-yl)propane-1-sulfonic acid inner salt as an electron-withdrawing group and 2-vinylthiophene as a π-bridge, and by utilizing mechanisms such as enhancing the conjugated chain length and replacing the donor.

3. The preparation and application of a type of D-π-A ionic near-infrared luminescent material according to claim 1, characterized in that, The target product has a strong emission spectrum in the near-infrared band (650 nm to 850 nm), with its tail extending into the near-infrared region, and has potential applications in the field of fluorescence imaging.

4. The preparation and application of a type of D-π-A ionic near-infrared luminescent material according to claim 1, characterized in that, Rationally designed D-π-A type materials not only ensure high luminous efficiency but also possess good stability and environmental adaptability, maintaining excellent performance in complex biological environments. These advantages make the D-π-A type structure one of the important strategies for designing high-performance near-infrared AIE materials, greatly promoting its research and application in fields such as bioimaging, photodynamic therapy, and multifunctional integrated diagnosis and treatment.

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