CN116478126B

CN116478126B - Preparation and application of A-D-A type organic micromolecular photosensitizer

Info

Publication number: CN116478126B
Application number: CN202310292719.6A
Authority: CN
Inventors: 甄士杰; 徐哲; 李美静
Original assignee: Guilin University of Technology
Current assignee: Guilin University of Technology
Priority date: 2023-03-23
Filing date: 2023-03-23
Publication date: 2024-10-15
Anticipated expiration: 2043-03-23
Also published as: CN116478126A

Abstract

The invention belongs to the field of biomedical materials, and discloses preparation and application of a strong A-D-A type organic micromolecular photosensitizer. The invention is based on a receptor-donor-receptor configuration, having the structure shown below: Wherein: ar is aromatic heterocycle and its derivative, X is hydrogen element or fluorine element or chlorine element. The invention builds strong receptor-donor-receptor and strong charge transfer state and simultaneously inhibits the intermolecular pi-pi stacking effect of molecules in the aggregation state by introducing groups such as strong electron-withdrawing cyano indenone, derivative and the like at two ends of donor triphenylamine or tetraphenyl ethylene and derivative, thereby endowing the material with AIE characteristics. In addition, heavy atoms such as fluorine atoms or chlorine atoms are introduced, so that the energy gap crossing of the excited singlet state to the triplet state is promoted to realize efficient active oxygen generation. Based on the high-efficiency fluorescence quantum efficiency and ROS production capability, the material provided by the invention has a good application prospect in fluorescence imaging-mediated tumor photodynamic therapy.

Description

Preparation and application of A-D-A type organic micromolecular photosensitizer

Technical Field

The invention belongs to the field of biomedical materials, and particularly relates to preparation and application of an A-D-A type organic micromolecular photosensitizer.

Background

The traditional photosensitizers mostly have planar structures and relatively poor water solubility, and are easy to cause dense pi-pi accumulation among molecules to cause excited state molecules to return to a ground state in a non-radiative transition mode of conversion, and the aggregated state not only can cause fluorescence quenching of the photosensitizers, but also can greatly reduce the photosensitizing efficiency of the photosensitizers. The discovery of the AIE phenomenon solves these problems well, and these AIE molecules not only have strong fluorescence in the aggregated state, but also have good photosensitizing efficiency. According to the perturbation theory, the method comprises the following steps, Enhancing spin-orbit coupling (SOC) or reducing the photosensitizer singlet (S ₁) to singlet (T ₁) bandgap difference (deltae _ST) can facilitate intersystem crossing (ISC) of singlet (S ₁) to singlet (T ₁), Thereby enhancing the photosensitivity efficiency of the photosensitizer. Spin-orbit coupling is a function of electron spin and orbit magnetic quantum number, and the stronger the nuclear electropositivity, namely the heavier the atoms, the stronger the coupling effect of electron spin and orbit magnetic quantum number, so that connecting the photosensitizer with heavy atoms is the most direct way of promoting intersystem crossing and improving the photosensitizer efficiency. The difference in energy between S ₁ and T ₁ is simply due to the mutual exclusion of the two opposite spin-direction valence electrons in S ₁ resulting in an energy above T ₁, The mutual exclusion of electrons and the distance between two valence electrons are in a negative correlation, Separation of HOMO and LUMO in S ₁ can effectively reduce the bandgap difference (Δe _ST) from S ₁ to T ₁. The addition of electron-withdrawing groups to the molecular structure of the photosensitizer may promote the separation of the photosensitizer HOMO and LUMO, thereby reducing the energy gap difference from singlet S ₁ to triplet T ₁.

Disclosure of Invention

Aiming at the problems, the AIE material with high near infrared luminous efficiency, adjustable absorption and emission spectrum and good light stability is designed and synthesized, and the interference of self-absorption and autofluorescence of biological tissues is overcome. The preparation of the near infrared luminescent AIE material is realized based on the cyano-indenone skeleton. Meanwhile, the photodynamic efficiency is improved by a method of reducing the level difference of the singlet state and the triplet state, and the near-infrared AIE material with high luminous efficiency and high photodynamic activity is screened out.

In order to achieve the above purpose, the present invention provides the following technical solutions: A-D-A organic small molecule photosensitizer is prepared and application thereof, and the preparation method comprises the following steps:

In nitrogen atmosphere, adding an aldehyde group-containing strong electron donor compound and cyano-indidone into a reactor at a molar ratio of 1:3, adding chloroform as a solvent, adding a catalyst pyridine, stirring the mixture by a magnetic stirring device to dissolve the mixture, heating the mixture to 80 ℃ for reaction for 3 hours, decompressing and evaporating the solvent after the reaction is finished to obtain a crude product, and purifying the crude product by column chromatography to obtain the target compound.

The structure is I

Wherein X = fluorine or chlorine;

ar=an aromatic ring electron donating group, and is any one of the following groups.

The invention has the beneficial effects that:

1. The invention synthesizes a new photosensitizer material system with AIE performance to overcome the problem of the decrease of tumor treatment effect caused by the fluorescence aggregation quenching effect and tumor hypoxia of the existing photosensitizer.

2. The near infrared photosensitizer with AIE property provided by the invention has stronger total active oxygen generating capacity than commercial photosensitizer chlorin (Ce 6).

3. The near infrared photosensitizer with AIE property provided by the invention has the advantages of few synthesis steps, simple method and easily available raw materials.

4. The near infrared photosensitizer with AIE property provided by the invention can have good fluorescence imaging effect on in-vitro cells and living tumors; even under the condition of hypoxia, the composition can still have good killing performance on cancer cells; but also has high-efficiency cure to the living tumor of the mice.

Drawings

FIG. 1 is a normalized absorption spectrum of TPAPT-4F and 2TPAPT-4F in THF;

FIG. 2 is a graph showing the emission spectra of the obtained materials TPAPT-4F and 2TPAPT-4F in THF

FIG. 3 shows the total active oxygen generating capacity of TPAPT-4F and 2TPAPT-4F, and the photosensitizer Ce 6.

FIG. 4 (A) and FIG. 4 (C) are graphs showing the fluorescence spectra under different water contents, and the fluorescence intensities of TPAPT-4F and 2TPAPT-4F are significantly increased after gradually adding water to THF solution, FIG. 4 (B) and FIG. 4 (D) are graphs showing the relationship between I/I ₀ of TPAPT-4F and 2TPAPT-4F and the water content of the solvent mixture

FIG. 5 is a mass spectrum of photosensitizer TPAPT-4F

FIG. 6 is a mass spectrum of photosensitizer 2TPAPT-4F

Detailed Description

The following technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, and thus the protection scope of the present invention is more clearly defined. The described embodiments of the present invention are intended to be only a few, but not all embodiments of the present invention, and all other embodiments that may be made by one of ordinary skill in the art without inventive faculty are intended to be within the scope of the present invention.

Example 1:

preparation of photosensitizer TPAPT-4F:

synthetic route for photosensitizer TPAPT-4F

Dibromotriphenylamine (0.4 g,0.99 mmol) (1), 5-aldehyde-2-thiopheneboronic acid (0.38 g,2.4 mmol), palladium acetate (0.012 g,0.05 mmol), X-Phos (0.04 g,0.08 mmol), potassium phosphate (1.72 g,7.9 mmol) were added to a mixture of 20mL tetrahydrofuran and water 1:1. After mixing and stirring uniformly, heating to 90 ℃ under the atmosphere of nitrogen, reacting for 12 hours, cooling to room temperature, and filtering the mixture 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. Yellow solid (2) was obtained in 45.7% yield (357 mg). 0.2g of the product and 5, 6-difluoro-3- (dicyanomethylene) indigonone (0.226 g,0.98 mmol) were weighed, a few drops of pyridine was added as a catalyst, reacted for 4 hours at 70 ℃, cooled to room temperature, the solvent was evaporated under reduced pressure, the appropriate chloroform was added for dissolution, a large amount of methanol was added to precipitate a solid, and the solid was filtered to obtain a dark black solid (0.2 g) with a yield of 93.8%.

The structural characterization data of the resulting product are shown below:

¹H NMR(400MHz,C₆D₆)δ7.35(s,1H),6.96(s,1H),5.32(s,1H),2.23(d,J＝20.4Hz,4H),1.87–1.54(m,4H),1.37(s,6H),0.87(d,J＝6.5Hz,1H),0.35(d,J＝42.8Hz,5H).

Example 2:

preparation of photosensitizer 2TPAPT-4F

The synthetic route is as follows:

Synthetic route for photosensitizer 2TPAPT-4F

4-Bromotrianiline (3.24 g,10 mmol) iodine (2.53 g,10 mmol) periodic acid (0.05 g,0.2 mmol) was dissolved in 50mL absolute ethanol and heated to 80℃for 4h, the reaction was cooled to room temperature, the mixture was filtered and the product (2) was used directly in the next reaction. The product of the previous step (2.33 g,3.8 mmol), diphenylamine (1.71 g,10 mmol), cuprous iodide (0.046 g,0.2 mmol), 1.10-phenanthroline (0.043 g,0.2 mmol) and potassium hydroxide (1.71 g,30 mmol) were weighed and reacted in 50mL toluene solution at 120℃for 36h. After cooling to room temperature, the mixture was filtered to remove insoluble impurities. Purification by column chromatography gave 1.2g of the desired product (3). The above product (0.6 g,0.97 mmol), 5-aldehyde-2-thiopheneboronic acid (0.34 g,2.2 mmol), tetrakis (triphenylphosphine) palladium (0.11 g,0.097 mmol), potassium carbonate (0.5 g,3.64 mmol) were weighed into 15mL THF and 15mL water, reacted under nitrogen atmosphere for 24h, cooled to room temperature, and the mixture was filtered to remove insoluble impurities. Purification by column chromatography gave 0.5g of the desired product (4) in 53% yield. 0.2g of the product and 5, 6-difluoro-3- (dicyanomethylene) indigonone (0.18 g,0.79 mmol) were weighed, a few drops of pyridine were added as a catalyst, reacted for 4 hours at 70 ℃, cooled to room temperature, the solvent was evaporated under reduced pressure, the appropriate chloroform was added for dissolution, a large amount of methanol was added to precipitate a solid, and the solid was filtered to obtain a dark black solid (0.2 g) with a yield of 78.9%.

The structural characterization data of the resulting product are shown below:

¹H NMR(400MHz,CD₂Cl₂)δ5.10(d,J＝22.3Hz,1H),2.04(s,3H),1.67(s,3H),1.53(s,13H),1.26(s,8H),0.87(d,J＝4.1Hz,4H).

Example 3:

Characterization of absorption spectra of A-D-A type photosensitizers (TPAPT-4F and 2 TPAPT-4F)

FIG. 1 is a graph of absorption spectra in THF of materials TPAPT-4F and 2TPAPT-4F obtained in examples 1 and 2, wherein the maximum absorption spectrum of TPAPT-4F in THF solution is 616nm, and the maximum absorption wavelength of 2TPAPT-4F is 640nm, showing that the absorption spectrum is significantly red shifted by enhancing the electron donating ability of electron donating groups, promoting the charge transfer in excited state molecules.

Example 4:

characterization of the emission spectra of type A-D-A photosensitizers (TPAPT-4F and 2 TPAPT-4F)

FIG. 2 is a graph of emission spectra in THF of materials TPAPT-4F and 2TPAPT-4F obtained in examples 1 and 2, with a maximum emission spectrum of TPAPT-4F in THF solution of 910nm and a maximum emission spectrum of 2TPAPT-4F of 977nm, indicating that the strong electron withdrawing effect of fluorine can impart ionic character to the C-F bond, which makes the C-F bond highly polarized, enhances electrostatic interactions between adjacent molecules, and promotes red shift of emission wavelength.

Example 5:

ROS-forming ability of A-D-A type photosensitizers

FIG. 3 is a graph comparing the total active oxygen generating capacity of TPAPT-4F and 2TPAPT-4F, and the photosensitizer Ce 6. The active oxygen probe DCFH, after binding to active oxygen, produced green fluorescence at 522 nm. The molecular concentration was 10. Mu.M in the test, and the optical density was 0.3W/cm ^-2 by irradiation with a 660nm laser. The results indicate that the TPAPT-4F and 2TPAPT-4F molecules are capable of producing higher fluorescence enhancement factors than Ce6, indicating that the TPAPT-4F and 2TPAPT-4F molecules have a greater ROS production capacity.

Example 6

FIGS. 4 (A) and 4 (C) are graphs of fluorescence spectra under different water content conditions, with the fluorescence intensities of TPAPT-4F and 2TPAPT-4F significantly increasing after gradual addition of water to the THF solution, and FIGS. 4 (B) and 4 (D) are graphs of I/I ₀ of TPAPT-4F and 2TPAPT-4F versus water content of the solvent mixture, with PL emissions of TPAPT-4F and 2TPAPT-4F quenched before the critical point (0% water fraction). After the critical point, the fluorescence intensity increased with the addition of water, indicating its aggregation-induced emission characteristics.

Claims

1. An A-D-A type organic small molecule photosensitizer is characterized in that:

wherein X = fluorine or chlorine; ar=aromatic ring electron donating group, any one of the following groups:

2. the use of a class of a-D-a type small organic molecule photosensitizers as claimed in claim 1 for the preparation of imaging agents for cancer cells.

3. The use of a class of small organic molecule photosensitizers as claimed in claim 1 for the preparation of photodynamic therapeutic agents for tumors.