Synthesis and application of D-pi-A type near-infrared AIE molecules

Abstract

The invention relates to synthesis and application of D-pi-A type near-infrared AIE molecules, in particular to a near-infrared AIE material constructed on the basis of 1, 4-dimethyl pyridine-1-onium iodide and a triphenylamine derivative. On the basis of combination of 1, 4-dimethyl pyridine-1-onium iodide and a triphenylamine derivative, through molecular design optimization, the compound has special electronic and optical performance, abundant excited state energy is provided for molecules, adjustment of a molecular conjugated system is achieved, and then the photophysical property is optimized. Meanwhile, the pyridinium salt has strong electron withdrawing capability and good water solubility, and can further enhance the intramolecular charge transfer (ICT) effect of D-pi-A type molecules and improve the luminous efficiency as a receptor. The D-pi-A type structure also enables the material to have better biocompatibility and cell membrane penetrability, and provides convenience for applications such as biological imaging and drug delivery. The structure can generate effective radiation luminescence through the ICT effect, so that the luminous efficiency is improved, and a new thought is provided for designing and developing a high-performance AIE material.

Description

Technical Field

[0001] This invention belongs to the field of biomedical materials and provides the synthesis and application of a class of D-π-A type near-infrared AIE molecules. Background Technology

[0002] Near-infrared organic light-emitting materials have advantages such as strong modifiability of chemical structure, good biocompatibility, high luminescence efficiency and fast response, and have become an important research direction for developing high-performance aggregation-induced emission (AIE) materials with special luminescence properties.

[0003] In recent years, near-infrared (NIR) aggregation-induced emission (AIE) materials have become a research focus due to their unique optical properties. Compared to traditional luminescent materials, NIR-AIE materials exhibit weaker absorption and scattering effects from substances such as water molecules and hemoglobin when propagating in biological tissues, resulting in significantly enhanced tissue penetration, reaching depths of several centimeters. Furthermore, they suffer from minimal interference from biological background fluorescence, leading to a substantial improvement in the imaging signal-to-noise ratio. Simultaneously, low-energy NIR light irradiation effectively reduces photodamage to biological samples, greatly improving the safety and accuracy of experiments. With these advantages, NIR-AIE materials hold immense potential in multiple fields.

[0004] In bioimaging, it enables high-resolution imaging of deep tissues and living organisms, aiding in early tumor diagnosis; in photodynamic therapy, it can precisely target lesions and efficiently kill cancer cells using singlet oxygen; in the field of chemical sensing, its high sensitivity to specific molecules makes it a powerful tool for detecting environmental pollutants and biomarkers; in organic optoelectronic devices, its high solid-state luminescence efficiency can optimize the performance of near-infrared detectors and optical communication devices. With further research, NIR-AIE materials are expected to bring more breakthroughs to life sciences and optoelectronic technologies. Compared to inorganic electrochromic materials, organic electrochromic materials have been widely studied and applied in recent years due to their lower processing temperature, higher tunability, and broad adaptability in various application fields. The flexibility and processability of organic materials demonstrate their enormous potential in emerging fields such as wearable devices and flexible display technologies. 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, thereby giving the materials better biocompatibility and cell membrane permeability, and providing convenience for applications such as bioimaging and drug delivery.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a near-infrared AIE material based on 1,4-dimethylpyridine-1-onium iodide and triphenylamine derivatives, and its application, the preparation method comprising the following steps:

[0007] Under a nitrogen atmosphere, 1,4-dimethylpyridine-1-onium iodide and a triphenylamine derivative were added to a two-necked round-bottom flask in a molar ratio of 1:2. The reaction flask was evacuated under vacuum, rinsed with dry nitrogen, and ethanol was added as a solvent and ammonium acetate as a catalyst. The mixture was heated to 70°C. o The reaction was carried out at C for 24 h. After the reaction was completed, the crude product was purified by silica gel column chromatography to obtain the target compound.

[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 1,4-dimethylpyridine-1-onium iodide and triphenylamine derivative. Through molecular design optimization, it provides abundant excited state energy to the molecule, realizes the adjustment of the molecular conjugated system, and thus optimizes the photophysical properties.

[0012] 2. The pyridine salt provided by this invention has strong electron-withdrawing ability and good water solubility. As an acceptor, it can further enhance the intramolecular charge transfer (ICT) effect of D-π-A type molecules and improve luminescence efficiency.

[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. Attached Figure Description

[0014] Figure 1 TT-py, BTT-py, and BTS-py in tetrahydrofuran solution (10) -5 The ultraviolet-visible (UV-Vis) absorption spectrum in M).

[0015] Figure 2 TT-py, BTT-py, and BTS-py in tetrahydrofuran solution (10) -5 The emission (PL) spectrum in M).

[0016] Figure 3 The fluorescence spectra of TT-py, BTT-py, and BTS-py in mixed solvents of THF and H2O with different water contents are shown.

[0017] Figure 4 The NMR spectrum of TT-py in deuterated DMSO (DMSO-d6).

[0018] Figure 5The NMR spectrum of BTT-py in deuterated DMSO (DMSO-d6).

[0019] Figure 6 The NMR spectrum of BTS-py in deuterated DMSO (DMSO-d6). 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:

[0022] The synthesis route for preparing the near-infrared luminescent material TT-py is as follows:

[0023]

[0024] TT-py: 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 given in 68.8% (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, 0.105 g (0.45 mmol) of 1,4-dimethylpyridine-1-onium iodide, and 0.020 g (0.05 mmol) of ammonium acetate. 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 red solid (0.22 g) with a yield of 79.4%.

[0025] The structural characterization data of the obtained product are shown below:

[0026] 1H NMR (500 MHz, CDCl3) δ 7.95 (d, J = 5.0 Hz, 2H), 7.33 (t, J = 35Hz, 3H), 6.78 (d, J = 15 Hz, 2H), 6.65 (d, J = 15 Hz, 2H), 6.53-6.49 (m, 4H),6.29-6.29 (m, 7H), 6.14 (d, J = 10 Hz, 2H), 3.37 (s, 3H)

[0027] Example 2: Preparation of near-infrared luminescent material BTT-py. The synthetic route is as follows:

[0028]

[0029] BTT-py: 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, 0.105 g (0.45 mmol) of 1,4-dimethylpyridine-1-onium iodide, and 0.020 g (0.05 mmol) of ammonium acetate. 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 red solid (0.18 g) with a yield of 65.3%.

[0030] The structural characterization data of the obtained product are shown below:

[0031] 1 H NMR (500 MHz, CDCl3) δ 8.80 (d, J = 5.0 Hz, 2H), 8.18-8.15 (m, 3H), 7.56 (s, 1H), 7.35-7.03 (m, 26H), 6.93 (d, J = 10 Hz, 2H), 6.87 (d, J = 10 Hz, 2H), 3.37 (s, 3H).

[0032] Example 3: Preparation of near-infrared luminescent material BTS-py, the synthetic route is as follows:

[0033]

[0034] BTS-py: 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, along with 0.2 g of the product from the previous step, 0.105 g of 1,4-dimethylpyridine-1-onium iodide (0.45 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 red solid (0.26 g) with a yield of 59.8%.

[0035] The structural characterization data of the obtained product are shown below:

[0036] 1 H NMR (500 MHz, CDCl3) δ 8.79 (d, J = 10.0 Hz, 2H), 8.21-8.16 (m,3H), 7.63 (d, J = 10.0 Hz, 2H), 7.51-7.47 (m, 2H), 7.38-7.30 (m, 6H), 7.12-6.98 (m, 16H), 4.21 (s, 3H).

[0037] Example 4: UV-Vis absorption spectra of TT-py, BTT-py, and BTS-py

[0038] Figure 1 To measure the optical properties of molecules in dilute tetrahydrofuran (THF) solution, we investigated their optical absorption characteristics by measuring the UV-Vis absorption spectra of three materials: TT-py, BTT-py, and BTS-py. Figure 1 The absorption spectra of three molecules in THF solution are shown. All molecules exhibit significant absorption characteristics in the 400-500 nm UV-Vis region, with a slight redshift in the absorption peak position of BTS-py compared to TT-py and BTT-py. This phenomenon indicates that with the increase of TPA chain length, the intramolecular electronic structure changes, leading to enhanced interactions between electronic orbitals and thus altering the optical absorption properties.

[0039] Example 5: Emission spectra of TT-py, BTT-py, and BTS-py

[0040] Figure 2 The emission spectra of TT-py, BTT-py, and BTS-py in THF are shown. In THF solution, the wavelengths corresponding to their maximum emission peaks are 672 nm, 618 nm, and 600 nm, respectively. Moreover, all three target products exhibit a wide emission range (600 nm-860 nm), which originates from various nonradiative transition processes such as vibrational relaxation and internal conversion in the excited state, reaching as far as the near-infrared I (NIR-I) region.

[0041] Example 6: Fluorescence spectra of TT-py, BTT-py, and BTS-py under different water content conditions

[0042] like Figure 3 As shown, the fluorescence intensity of TT-py increases with increasing water content, reaching its maximum at fw=80%, indicating that the single bonds within the molecule cannot rotate freely in the aggregated state, hindering the non-radiative energy consumption and ultimately leading to luminescence of the molecular aggregates. The fluorescence intensity of BTT-py decreases with increasing water content from fw=0% to 80%, reaching its maximum at fw=90%, indicating its aggregation-induced emission characteristics.

Claims

1. Synthesis and application of a class of D-π-A type near-infrared AIE molecules, characterized in that, The characteristic structure of this molecule is shown in I-III below: 。 2. The synthesis and application of a type D-π-A near-infrared AIE molecule according to claim 1, characterized in that, Based on the redshift of emission wavelength achieved by triphenylamine and its derivatives through strong charge transfer states between donor and acceptor, near-infrared luminescent AIE materials are obtained, enriching the near-infrared AIE material system.

3. The synthesis and application of a class of D-π-A type near-infrared AIE molecules according to claim 1, characterized in that, The D-π-A type structure can produce a significant ICT effect in the excited state, which is conducive to the efficient emission transition of excited-state molecules and significantly enhances their luminescence intensity. In addition, the conjugation properties of D-π-A type structure molecules and their rational molecular design can also significantly improve the solubility and dispersibility of materials, increase the biocompatibility of materials, and make them easier to use in aqueous solutions or biological systems.

4. The synthesis and application of a type D-π-A near-infrared AIE molecule according to claim 1, characterized in that, Materials with pyridinium salt structures typically possess strong polarity, which facilitates their efficient penetration across cell membranes and enhances their targeting within cells; this is crucial for applications such as bioimaging, targeted drug delivery, and disease diagnosis.

Images