Preparation and application of fluorocyano indanone near-infrared molecule

Abstract

The invention belongs to the field of organic photoelectric materials and biomedical treatment, and discloses preparation and application of a class of fluorocyano indanone near-infrared molecules. According to the invention, fluorine atoms are introduced into a strong electron withdrawing group cyano indanone, and 3, 4-ethylenedioxythiophene is used as a pi bridge to construct a near-infrared material with two electron donating groups. According to the invention, two fluorine atoms are introduced into an electron withdrawing group cyano indanone, so that the electron withdrawing capability is further enhanced, and two D-pi-A type fluorescent molecules are designed and synthesized. The fluorine (F) is introduced into the 3-dicyanoethylene indene-1-ketone, so that the electron withdrawing effect is further enhanced. The C-F bond has ionicity due to the strong electron withdrawing effect of fluorine, so that the C-F bond is highly polarized, the electrostatic interaction between adjacent molecules is enhanced, and the red shift of the absorption wavelength can be promoted. A thought is provided for the design of the molecules.

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 fluorinated cyanoindigo ketone near-infrared materials by increasing electron-withdrawing ability to reduce the bandgap and thus promoting emission redshift, as well as its application. Background Technology

[0002] The unique n-π* transition properties and strong electron-withdrawing ability of 3-dicyanoethylene-indene-1-one can promote efficient intersystem crossing and intramolecular charge transfer processes. Simultaneously, the stretching vibrations of the active C═O double and C≡N triple bonds in 3-dicyanoethylene-indene-1-one significantly contribute to the nonradiative relaxation of the excited state. Furthermore, introducing fluorine (F) into 3-dicyanoethylene-indene-1-one further enhances the electron-withdrawing effect. This is mainly because the strong electron-withdrawing effect of fluorine makes the CF bond ionic, highly polarized, and enhances the electrostatic interaction between adjacent molecules, promoting a redshift in absorption wavelength. In addition, fluorination can significantly promote drug binding interactions and metabolic stability, thereby facilitating drug uptake and reducing drug toxicity. Based on this, Zhen's research group constructed a series of near-infrared II (NIR-II) photosensitizers (PS) with aggregation-induced emission (AIE), NIR-II fluorescence imaging (FLI), type I photodynamic therapy (PDT), and mild photothermal therapy (PTT) using a dual-strategy approach combining donor group engineering and fluorination engineering. Benefiting from ample molecular rotors and the high electronegativity of fluorine, the developed BTS-2F and TTS-2F exhibit NIR-II AIE properties, high reactive oxygen species (ROS) generation capacity, and mild photothermal conversion. Summary of the Invention

[0003] To address the above issues, a method will be designed and synthesized to reduce the band gap of a class of near-infrared materials by increasing electron-withdrawing ability. This involves introducing a cyanoindoketone group as an acceptor to a fluorine atom, which, together with an electron-donating group, constructs a DA backbone. Within the DA backbone, 3,4-ethylenedioxythiophene is used to extend the π-conjugation length. By utilizing mechanisms such as enhanced conjugated chain length and intramolecular charge transfer, AIE near-infrared II region materials can be prepared.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for reducing the band gap of a class of fluorocyanoindole near-infrared molecules by increasing electron-withdrawing properties, the preparation method comprising the following steps:

[0005] In a nitrogen atmosphere, 3,4-ethylenedioxythiophene aldehyde containing triphenylamine or tetraphenylethylene and 5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-yl)malononitrile were added to the reactor at a molar ratio of 1:1.5. Chloroform was added as a solvent, and pyridine was used as a catalyst. The mixture was stirred with a magnetic stirrer until dissolved. 70o The reaction was carried out at C for 4 h. After the reaction was completed, the solvent was removed by vacuum distillation to obtain the crude product, which was then purified by column chromatography to obtain the target compound.

[0006] The structure is:

[0007]

[0008] Beneficial effects of this invention:

[0009] 1. This invention synthesizes a class of near-infrared materials by introducing fluorine atoms into cyanoindone to increase its electron-withdrawing effect, and by utilizing mechanisms such as enhanced conjugated chain length and intramolecular charge transfer to achieve the preparation of AIE near-infrared materials.

[0010] 2. The near-infrared material provided by this invention introduces fluorine atoms as acceptors based on cyanoindoketone groups to construct a DA backbone with electron-donating groups. In the DA molecular backbone, 3,4-ethylenedioxythiophene is used to extend the π conjugation length. By utilizing mechanisms such as enhanced conjugation chain length and intramolecular charge transfer, the AIE near-infrared II region material is prepared.

[0011] 3. The synthesis of the D-π-A type near-infrared material provided by this invention has few steps, is simple, and uses readily available raw materials.

[0012] 4. The near-infrared material provided by this invention has an emission wavelength of 925 nm and a tail extending into the near-infrared II region. Attached Figure Description

[0013] Figure 1 A and B are the absorption spectra of 2F-ET and 2F-ETPE, respectively;

[0014] Figure 2 A and B are the emission spectra of 2F-ET and 2F-ETPE, respectively;

[0015] Figure 3 The NMR spectrum of 2F-ET;

[0016] Figure 4 The NMR spectrum is 2F-ETPE. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the scope of protection of the present invention. The embodiments described in this invention are only some embodiments of the present invention, not all embodiments. 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.

[0018] Example 1:

[0019] Preparation of 2F-ET:

[0020]

[0021] Synthetic route of 2F-ET

[0022] Synthesis of 2F-ET: Under a nitrogen atmosphere, 5-bromo-2-(3,4-ethylenedioxythiophene)carboxaldehyde (0.20 g, mmol), triphenylamine 4-borate (0.6 g, 1.2 mmol), tetrakis(triphenylphosphine)palladium (0.05 g, 0.04 mmol), and potassium carbonate (0.2 g, 1.2 mmol) were added to 30 mL of a mixed solvent of toluene, ethanol, and water in an 8:1:1 ratio. The reaction was carried out at 90 °C for 12 h. After the reaction was completed, the system was cooled, concentrated under reduced pressure, and separated by silica gel column chromatography to obtain a yellow solid product (0.2 g, 60% yield). 0.2 g of the above product was dissolved in chloroform with 5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-yl)malononitrile (0.1 g, 0.5 mmol), and a few drops of pyridine catalyst were added. The solution was then dissolved at 70 °C. o The reaction mixture was refluxed at C for 4 h. After post-treatment (concentration, dissolution in dichloromethane, and crystallization in methanol), the solution was filtered to collect a dark black solid (0.16 g, yield 56%). The NMR structure is shown below. Figure 3 As shown.

[0023] The structural characterization data of the obtained product are shown below:

[0024] 1 H NMR (500 MHz, CDCl3) δ 9.06 (s, 1H), 8.52 (s, 1H), 7.87 (d, J = 8.4Hz, 2H), 7.64 (s, 1H), 7.34 (d, J = 7.5 Hz, 5H), 7.19 (d, J = 8.3 Hz, 5H), 7.06 (d, J = 8.4 Hz, 2H), 4.49 (d, J = 73.1 Hz, 4H).

[0025] Example 2:

[0026] Preparation of 2F-ETPE:

[0027]

[0028] Synthetic route of 2F-ETPE

[0029] Synthesis of 2F-ETPE: Under a nitrogen atmosphere, 5-bromo-2-(3,4-ethylenedioxythiophene)carboxaldehyde (0.20 g, 0.8 mmol), 1-(4-phenylboronic acid pinacol ester)-1,2,2-triphenylethylene (0.55 g, 1.2 mmol), tetrakis(triphenylphosphine)palladium (0.05 g, 0.04 mmol), and potassium carbonate (0.2 g, 1.2 mmol) were added to 30 mL of a mixed solvent of toluene, ethanol, and water in an 8:1:1 ratio. The reaction was carried out at 90 °C for 12 h. After the reaction was complete, the system was cooled, concentrated under reduced pressure, and separated by silica gel column chromatography to obtain a yellow solid product (0.25 g, yield 63%). Take 0.5 g of the above product and dissolve 0.23 g (1.2 mmol) of 5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-yl)malononitrile in chloroform, add a few drops of pyridine as a catalyst, and 70 o The reaction mixture was refluxed at C for 4 h. After post-treatment (concentration, dissolution in dichloromethane, and crystallization in methanol), the solution was filtered to collect a dark black solid (0.4 g, 60% yield). The NMR structure is shown below. Figure 4 As shown.

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

[0031] 1 H NMR (500 MHz, CDCl3) δ 9.07 (s, 1H), 8.59–8.48 (m, 1H), 7.83–7.60 (m, 3H), 7.31 (d, J = 14.9 Hz, 3H), 7.25–6.87 (m, 16H), 4.60–4.35 (m, 4H).

[0032] Example 3:

[0033] Absorption spectral characterization of near-infrared materials 2F-ET and 2F-ETPE

[0034] Figure 1 A and Figure 1 B shows the absorption spectra of materials 2F-ET and 2F-ETPE obtained in Examples 1 and 2 in THF. The maximum absorption spectrum of 2F-ET in THF solution is 625 nm, while the maximum absorption wavelength of 2F-ETPE is 571 nm.

[0035] Example 4:

[0036] Emission spectral characterization of 2F-ET and 2F-ETPE

[0037] Figure 2The emission spectra of 2F-ET and 2F-ETPE obtained in Examples 1 and 2 in THF at room temperature are shown. Figure 2 A represents the emission spectrum of 2F-ET in THF at room temperature. Figure 2 B is the emission spectrum of 2F-ETPE, which reaches an emission wavelength of 925 nm in THF solution.

[0038] Example 5

[0039] Attached diagrams for 2F-ET and 2F-ETPE.

Claims

1. Preparation and application of a class of near-infrared molecules of fluorocyanoindole, characterized by the following: 。 2. The preparation and application of a type of near-infrared molecule of fluorocyanoindole according to claim 1, characterized in that: Cyanoindoketone has a strong electron-withdrawing ability, which can achieve a low LUMO energy level and form a strong π-packing, thus achieving a high electron mobility. Introducing one or more fluorine atoms into cyanoindoketone can further enhance the electron-withdrawing ability, thereby modulating the LUMO energy level and redshift absorption spectrum.

3. The preparation and application of a type of fluorocyanoindole near-infrared molecule according to claim 1, characterized in that: By increasing electron-withdrawing ability to reduce molecular band gap, stronger acceptors are more conducive to enhancing ICT process and effectively promoting wavelength redshift; Structure II has an emission peak of 925 nm in tetrahydrofuran (THF) solution, and its tail can enter the near-infrared II region; it has potential applications in fluorescence imaging.

4. The preparation and application of a type of fluorocyanoindole near-infrared molecule according to claim 1, characterized in that: By introducing fluorine atoms as electron-withdrawing groups into cyanoindoketone and using 3,4-ethylenedioxythiophene (EDOT) as a π-bridge, near-infrared materials can be prepared by utilizing mechanisms such as enhanced conjugated chain length and intramolecular charge transfer.

5. The preparation and application of a class of fluorocyanoindole near-infrared molecules according to claim 1, and the method for preparing near-infrared materials by increasing electron-withdrawing ability and its application, characterized in that: By selecting strong electron acceptors and introducing intramolecular charge transfer (ICT) mechanisms, and by designing intramolecular rotation, the formation of ICT states is promoted, thereby achieving redshift emission.

Images