CN113583033B

CN113583033B - benzothiadiazole-TB-fluoroboron complex and synthesis method and application thereof

Info

Publication number: CN113583033B
Application number: CN202110869229.9A
Authority: CN
Inventors: 吴翚; 李连峰; 周杭; 苑睿; 张鹏; 宛瑜
Original assignee: Jiangsu Normal University
Current assignee: Jiangsu Normal University
Priority date: 2021-07-30
Filing date: 2021-07-30
Publication date: 2022-05-10
Anticipated expiration: 2041-07-30
Also published as: CN113583033A

Abstract

The invention discloses a benzothiadiazole-TB-fluoroboron complex, a synthesis method and an application thereof, wherein the structural formula of the complex is shown as a formula A:

the benzothiadiazole-TB-fluoroboron complex has large Stokes displacement, shows excellent luminescence performance, has excellent solid luminescence and has the potential of becoming an excellent OLED material; has wide pH application range and can be applied to human physiological environment; the probe has effective and good response to viscosity and can become a fluorescent probe with viscosity response; for Fe³⁺And Cu²⁺Has identification ability and is expected to be excellent Fe³⁺And Cu²⁺A fluorescent probe; the PDT photosensitizer has a good PDT effect, can be used for dyeing and imaging A549 cells, expands the types of the photosensitizer, and provides a new idea for synthesizing imaging-guided PDT photosensitizer.

Description

benzothiadiazole-TB-fluoroboron complex and synthesis method and application thereof

Technical Field

The invention belongs to the field of organic synthesis, analytical chemistry and biological imaging, and particularly relates to benzothiadiazole-containing material with excellent optical performance

The synthesis of base-fluoroboron complexes and their use in metal ion recognition, photodynamic therapy and bioimaging.

Background

Photodynamic Therapy (PDT) is a new method for treating diseases such as tumors by using photosensitive drugs and laser activation. The traditional Chinese medicine composition has the advantages of low side effect, minimal invasion, no obvious drug resistance, high tumor destruction selectivity, easiness in combination with other therapies and the like, and becomes an important emerging means for accurate clinical tumor treatment. Photosensitizer is the core of PDT, and the traditional PDT photosensitizer has the problems of poor visible absorption, poor penetrability and the like, so more and more novel high-efficiency photosensitizer are developed. But based on

The photosensitizer of base (TB) skeleton is still in the primary stage, and only one relevant report is available.

Proper biocompatibility is an important factor affecting the performance of PDT photosensitizers and fluorescence imaging contrast agents, among others. The fluoroboric fluorescent dye has the advantages of high fluorescence quantum yield, higher molar extinction coefficient, narrower fluorescence absorption and emission peak, better light stability, good biocompatibility and the like, and is widely applied to the fields of biological medicine, pH probes, biological imaging, metal ion detection and the like. The coordination mode of the fluoroboric fluorescent compound mainly comprises the coordination of atoms such as N, N-, O-, N, O-and the like with a B atom (figure 1). The traditional fluorine boron fluorescent dye is a highly planar structure, has strong intermolecular pi-pi accumulation, causes large self-absorption and is easy to generate a fluorescence quenching phenomenon, has small Stokes displacement, is easy to be influenced by excitation light and scattered light, and has limited application in the fields of biological imaging and the like. Therefore, the fluoroboric compound is modified to obtain the fluorescent compound with large Stokes shift, which is favorable for expanding the application of the fluoroboric compound in the fields of biological and tissue imaging and other optics.

Therefore, the invention is achieved by

Introducing benzothiadiazole, boron fluoride and triphenylamine group on base (TB) skeleton, designing and synthesizing benzothiadiazole-TB-boron fluoride complex, and applying it to metalIon recognition, photodynamic therapy, biological imaging, and the like.

Disclosure of Invention

The invention aims to provide a benzothiadiazole-TB-fluoroboron complex, a synthesis method and application thereof

The base-fluoroboron complex is applied to the fields of metal ion identification, photodynamic therapy, biological imaging and the like.

A benzothiadiazole-TB-boron fluoride complex has a structural formula shown as formula A:

a method for synthesizing benzothiadiazole-TB-boron fluoride complex comprises the following steps:

(1) reacting the compound 1 with paraformaldehyde to obtain an intermediate 2, wherein the reaction formula is as follows:

(2) the intermediate 2 reacts with trimethyl borate to obtain an intermediate 3, and the reaction formula is as follows:

(3) the intermediate 3 and 4, 7-dibromo-benzothiadiazole 4 are subjected to coupling reaction to obtain a compound 5, wherein the reaction formula is as follows:

(4) hydrolysis of compound 5 affords compound 6, the reaction scheme is as follows:

(5) compound 6 reacts with boron trifluoride to give intermediate 7, of the formula:

(6) the intermediate 7 reacts with 4-triphenylamine borate 8 to obtain a compound 9, and the reaction formula is as follows:

the benzothiadiazole-TB-fluoroboron complex is applied as a photosensitizer for photodynamic therapy.

The benzothiadiazole-TB-fluoroboron complex is applied to biological imaging as a fluorescent material.

The benzothiadiazole-TB-fluoroboron complex is used as Fe³⁺And Cu²⁺The application of the fluorescent probe in metal ion recognition.

Has the advantages that: the benzothiadiazole-

The base-fluoroboron complex has the following advantages:

(1) the synthesis method is simple, and the post-treatment is convenient;

(2) the material has large Stokes shift, excellent luminescence property, excellent solid-state luminescence and potential of becoming an excellent OLED material;

(3) has wide pH application range and can be applied to human physiological environment;

(4) the probe has effective and good response to viscosity and can become a fluorescent probe with viscosity response;

(5) for Fe³⁺And Cu²⁺Has identification ability and is expected to be excellent Fe³⁺And Cu²⁺FluorescenceA probe;

(6) the PDT photosensitizer has a good PDT effect, can be used for dyeing and imaging A549 cells, expands the types of the photosensitizer, and provides a new idea for synthesizing imaging-guided PDT photosensitizer.

Drawings

FIG. 1 is a schematic representation of the coordination of N, N-, O, O-and N, O-containing ligands to the B atom;

FIG. 2 is a UV absorption spectrum of Compound A in various solvents;

FIG. 3 shows fluorescence emission spectra of Compound A in different solvents;

FIG. 4 is the UV absorption spectra of

compounds

5, 6, 7 and A in DMF;

FIG. 5 is the fluorescence emission spectra of

compounds

5, 6, 7 and A in DMF;

FIG. 6 is a solid state fluorescence emission spectrum of

compounds

5, 6 and A;

FIG. 7 is a fluorescence emission spectrum (a) and a line graph (b) of Compound A at different viscosities;

FIG. 8 is a fluorescence emission spectrum (a) and a line graph (b) of Compound A at different pH;

FIG. 9 is the fluorescence emission spectrum (a) of Compound A and the fluorescence emission spectrum (b) of the presence of different biological thiols;

FIG. 10 shows the concentration of Fe in compound A³⁺Fluorescence emission spectrum (a) and line graph (b) in the presence;

FIG. 11 shows the concentration of Fe in compound A³⁺Fluorescence emission spectrum (a) and standard curve (b) in the presence;

FIG. 12 is compound A-Fe³⁺The Job's curve of the system;

FIG. 13 is the toxicity of different concentrations of A on human bronchial epithelial-like cells (HBE);

FIG. 14 is the survival of A549 cells in the presence of A in the absence of light (L +) or in the presence of A;

FIG. 15 is a fluorescence micrograph of A vs A549 cells in the absence of illumination (L-) and illumination (L +);

FIG. 16 is intermediate of Compound 5 of the examples¹H NMR spectrum;

FIG. 17 intermediate product materialization of the exampleProcess for preparation of Compound 5¹³C NMR spectrum;

FIG. 18 is intermediate product of example Compound 6¹H NMR spectrum;

FIG. 19 is intermediate product of compound 6 of the example¹³C NMR spectrum;

FIG. 20 is of the product of example, Compound A¹H NMR spectrum;

FIG. 21 is of the product of example, Compound A¹³C NMR spectrum.

Detailed Description

According to the invention, diazosulfide, boron fluoride and triphenylamine group are introduced into a TB skeleton, so that a diazosulfide-TB-boron complex is designed and synthesized, and the diazosulfide-TB-boron complex is applied to the fields of metal ion identification, photodynamic therapy, biological imaging and the like.

The structural formula of the benzothiadiazole-TB-boron complex is shown as A:

the present invention will be further described with reference to the following examples.

The following describes embodiments of the present invention in detail. The following examples are illustrative only and are not to be construed as limiting the invention. It will be understood by those skilled in the art that various changes and modifications may be made to the invention without departing from the spirit and scope of the invention.

Examples

In this example, benzothiadiazole-

The base-fluoroboron complex is shown in Table 1.

TABLE 1

In this embodiment, the method for synthesizing the benzothiadiazole-TB-fluoroboron complex includes the following steps:

reacting the compound 1 with paraformaldehyde to obtain an intermediate 2, reacting the intermediate 2 with trimethyl borate to obtain an intermediate 3, performing coupling reaction on the intermediate 3 and 4, 7-dibromo-benzothiadiazole 4 to obtain an intermediate 5, hydrolyzing the intermediate 5 to obtain an intermediate 6, reacting the intermediate 6 with boron trifluoride to obtain an intermediate 7, and reacting the intermediate 7 with 4-triphenylamine borate 8 to obtain a compound A. The method comprises the following specific steps:

(1) 4-bromo-3-methoxyaniline 1(50.0mmol) and paraformaldehyde (100.0mmol) were sequentially added to a 200mL round-bottomed flask, the flask was placed in a cryotank, the temperature was adjusted to-15 ℃, trifluoroacetic acid (100mL, about 30min after completion of dropwise addition) was slowly added to the flask with stirring, and the reaction was carried out at room temperature for 7 days. After completion of the reaction (TLC trace), the mixture was poured into ice water, adjusted to pH 9-10 with ammonia, cooled to room temperature, filtered with suction, and washed three times with ethanol to give intermediate 2.

Equation 1 TB-OCH₃Synthesis of-Br (2)

(3) Adding the intermediate 2(5.0mmol) into a 100mL round-bottom flask, vacuumizing for three times, placing the flask in a low-temperature tank, adjusting the temperature to-78 ℃, adding 20.0mL anhydrous tetrahydrofuran into the flask under stirring, dropwise adding 2.5mL n-butyl lithium, reacting for 1h under argon protection, dropwise adding 0.6mL trimethyl borate, and then placing the flask at room temperature for reacting for 4 h. TLC trace to completion of reaction, dichloromethane extraction (30.0 mL. times.3) and spin-drying to give crude product. The crude product is purified by column chromatography (V)_PE:V_EA1: 5) to give intermediate 3 (70%).

Equation 2 Synthesis of intermediate 3

(4) The intermediate 3(2.0mmol), 4, 7-dibromo-benzothiadiazole 4(4.8mmol), and tetrakis (triphenylphosphine) palladium (20% mmol,0.06g) were sequentially charged into a 100mL round-bottomed flask35.0mL of anhydrous toluene was added under an argon atmosphere, followed by addition of potassium carbonate (0.53g), and the reaction was carried out at 108 ℃ for 12 hours. After completion of the reaction (TLC chase), it was cooled to room temperature, extracted with dichloromethane (10.0 mL. times.3), the organic phase was dried over anhydrous sodium sulfate, and dried to give a crude product which was purified by column chromatography (V)_DCM:V_EA100:1) to give compound 5 (70%).

Equation 3 Synthesis of Compound 5

Compound 5: 7,7' - (3, 9-dimethoxy-6H, 12H-5, 11-dibenzo [ b, f ] [1,5] diazocine-2, 8-diyl) bis (4-bromobenzo [ c ] [1,2,5] thiadiazole)

¹H NMR(400MHz,CDCl₃)δ7.82(d,J＝7.2Hz,1H,Ar-H),7.40(d,J＝7.6Hz,1H,Ar-H),7.02(s,1H,Ar-H),6.85-6.61(m,5H,Ar-H),4.73-4.68(m,2H,-CH₂-bridge),4.32-4.18(m,4H,TB-CH₂*2),3.73(d,J＝8.8Hz,6H,-OCH₃*2).¹³C NMR(100MHz,CDCl₃)δ159.1,156.3,153.9,153.4,149.7,149.0,132.0,131.2,130.2,129.7,127.8,122.2,120.0,119.8,112.8,111.3,109.6,107.9,66.8,58.2,58.1,55.8,55.4.

(5) And (3) putting the compound 5(2.0mmol) in a 50mL round-bottom flask, vacuumizing for three times, placing the flask in a low-temperature tank, adjusting to-15 ℃, adding 15.0mL of anhydrous dichloromethane, dropwise adding boron tribromide, moving the reaction bottle to room temperature after dropwise addition, and continuing to react for 12 hours under the protection of argon. After completion of the reaction (TLC chase), water was added for quenching, dichloromethane was extracted (10.0 mL. times.3), and the organic phase was dried over anhydrous sodium sulfate to give compound 6 (75%) after spin-drying.

Equation 4 Synthesis of Compound 6

Compound 6: 2, 8-bis (7-bromobenzo [ c ] [1,2,5] thiadiazol-4-yl) -6H,12H-5, 11-dibenzo [ b, f ] [1,5] diazocine-3, 9-diol

¹H NMR(400MHz,DMSO-d₆)δ8.06(d,J＝7.6Hz,1H,Ar-H),7.58(d,J＝7.6Hz,1H,Ar-H),7.22(s,1H,Ar-H),7.03(d,J＝8.4Hz 1H,Ar-H),6.96(s,1H,Ar-H),6.79-6.71(m,3H,Ar-H),4.88-4.80(m,4H,TB-CH_2*2),4.32(dd,J₁＝6.0Hz,J₂＝16.0Hz,2H,-CH₂-bridge).¹³C NMR(100MHz,DMSO-d₆)δ157.6,155.1,153.7,153.1,132.7,130.8,130.7,130.4,128.9,112.4,111.3,110.7,66.3,56.9.

(6) Compound 6 reacts with boron trifluoride to give intermediate 7, of the formula:

equation 5 Synthesis of Compound 6

Weighing the compound 6(2.0mmol) in a 50mL round-bottom flask, placing the flask in a low-temperature tank, adjusting the temperature to-15 ℃, adding 15mL of anhydrous dichloromethane under the protection of argon, then adding 10mL of triethylamine (48mmol), stirring for 30min, then slowly dropwise adding 10mL of boron trifluoride diethyl etherate (48mmol), and after dropwise adding, continuing the reaction at room temperature for 24 h. After completion of the reaction (TLC chase), quenched with water, extracted with dichloromethane (10.0mL 3) and the crude product purified by column chromatography (V)_DCM:V_MeOH120:1) gave intermediate 7 (35%) which was used directly in the next reaction.

(7) The intermediate 7 reacts with 4-triphenylamine borate 8 to obtain a compound A, and the reaction formula is as follows:

equation 6 Synthesis of product A

Compound 7(2.0mmol), 4-triphenylamine borate 8(4.8mmol), tetrakis (triphenylphosphine) palladium (0.06g) and potassium carbonate (0.53g) were sequentially charged in a 100.0mL round-bottomed flask, and after purging three times, 35mL of anhydrous toluene was added, followed by reaction at 108 ℃ for 24 hours. After completion of the reaction (TLC follow-up), quenching with water, extraction with dichloromethane (20.0 mL. times.3) and column chromatography of the crude productPure (V)_DCM:V_MeOH80:1) to obtain compound a (54%).

A compound A:

¹H NMR(400MHz,DMSO-d₆)δ9.42(s,1H,Ar-H),9.24(s,1H,Ar-H),7.94(d,J＝8.4Hz,2H,Ar-H),7.82(d,J＝7.2Hz,1H,Ar-H),7.71(d,J＝7.6Hz,1H,Ar-H),7.38–7.34(m,4H,Ar-H),7.12-7.06(m,8H,Ar-H),6.79(d,J＝8.4Hz,1H,Ar-H),6.70(s,1H,Ar-H),6.49–6.42(m,2H,Ar-H),4.56(d,J＝16.4Hz,2H,-CH₂-bridge),4.20(s,2H,TB-CH₂),4.06-4.01(m,2H,TB-CH₂).¹³C NMR(100MHz,DMSO-d₆)δ156.8,154.9,154.4,153.5,149.6,147.8,147.5,131.5,131.2,130.6,130.5,130.2,128.1,127.6,125.0,124.1,122.9,121.2,118.8,112.2,111.7,111.3,66.7,58.4,58.3.

solvation effect

The solvating effect of compound a obtained in the examples was tested, and the specific experimental protocol was as follows:

compound A is prepared into a concentration of 1 × 10 by using eight solvents of Dichloromethane (DCM), Tetrahydrofuran (THF), methanol (MeOH), acetonitrile (MeCN), dimethyl sulfoxide (DMSO), Toluene (Toluene), N, N-Dimethylformamide (DMF) and N-Hexane (N-Hexane) respectively^-5The working solution in mol/L is tested for ultraviolet absorption spectrum and fluorescence emission spectrum, as shown in the attached figures 2 and 3.

As can be seen from FIGS. 2 and 3, Compound A is in a highly polar solvent_emA red shift occurs, indicating that it has ICT effects.

The ultraviolet absorption of A occurs around 300nm and is attributed to the B band absorption caused by pi-pi + transition on an aromatic ring; and its uv absorption at 410nm is attributed to the R-band absorption caused by n-pi + transition on the heteroatom.

Test for luminescent Properties

Compound 5, compound 6, compound 7 and compound a were tested for uv absorption and fluorescence emission spectra in DCM solution (fig. 4 and 5).

The solid-state fluorescence emission spectra of compound 5, compound 6 and compound a were tested (fig. 6).

The specific test scheme is as follows:

weighing 10^-5Adding mol of compound 5, compound 6, compound 7 and compound A, and fixing the volume with DCM solution to the concentration of 1 × 10^-5And (5) testing ultraviolet absorption, fluorescence emission and solid state fluorescence emission spectra of the sample at mol/L.

The spectral data for compound 5, compound 6, compound 7 and compound a are shown in table 2.

As is clear from table 2, the absorbance of compound a was greatly increased as compared with compound 6 and compound 7, and the absorbance of compound a was slightly increased as compared with compound 5, and under the same conditions, the molar absorption coefficient of compound a was 4 times that of compound 7, because the HOMO/LUMO energy gap of compound a was smaller, which was favorable for electron flow, and the molar absorption coefficient was increased. Compound A has a longer lambda_em(637nm) and greater Stokes shifts (328 nm). The large Stokes displacement and red light emission are beneficial to reducing the influence of excitation light and scattered light on fluorescence emission, can effectively shield biological background interference, and are beneficial to expanding the application of the fluorescent material in aspects of biological imaging and the like.

TABLE 2 spectroscopic Data (DCM) for

Compounds

5, 6, 7 and A

^aUltraviolet absorption wavelength in solution (slit is 2.5/5 nm);^bmolar extinction coefficient ε is A/bC, unit is 1 × 105L mol^-1·cm^-1(ii) a c fluorescence emission wavelength in solution;^dstokes shift in solution;^erelative fluorescence quantum yield (reference: quinine sulfate);^ffluorescence intensity in L.mol^-1·cm^-1；^gSolid state excitation wavelength (slit 2.5/2.5 nm);^ha solid state fluorescence emission wavelength;ⁱsolid-state Stokes shift. "-" indicates that the intensity was too low to test.

Viscosity response test

The response of compound A to viscosity (DMSO: glycerol is 1:9-10:0 in sequence) (lambda) was tested_ex310nm, slit: 5/10nm) (FIG. 7). As can be seen from FIG. 7, when the content of glycerin is increasedAt 10% and 20%, the fluorescence intensity slightly increased, probably because the increase in viscosity restricted intramolecular rotation of compound a, increasing its molecular rigidity, and thus slightly increased the fluorescence intensity. When the glycerol content was further increased, the fluorescence intensity began to decrease, probably because the increase of the hydrogen bond donor in the protic solvent caused the compound a to form intermolecular hydrogen bonds, resulting in fluorescence quenching.

pH response test

The response of Compound A to pH (. lamda.) was tested_ex310nm, slit: 5/10nm) (FIG. 8). As can be seen from FIG. 8, when the pH of the solution is 2-10, the fluorescence emission spectrum of the compound A has no obvious change, which indicates that the compound A has a wide pH application range and can be applied to human physiological environments.

Identification of metal ions and Biothiols

The response of Compound A to different ions and Biothiols (. lamda.) was tested_ex310nm, slit: 5/10nm, as shown in FIG. 9 and Table 3)

TABLE 3 Effect of Compound A with different Ionic, Biothiols

As can be seen from the combination of FIG. 9 and Table 3, the addition of Fe³⁺And Cu²⁺Then, the fluorescence intensity of compound a decreased by 99% and 78%, respectively; whereas when other metal ions, anions or biological thiols were added, the change in fluorescence intensity was negligible, indicating that Compound A is Fe³⁺The best recognition effect is achieved; the influence of the interfering ions on the compound A is small, which indicates that the compound A has little influence on Fe³⁺And Cu²⁺With more efficient recognition.

Compounds A and Fe³⁺After action, its lambda_emA significant red shift occurs, indicating that it is associated with Fe³⁺Coordination may occur. We therefore further investigated Compound A for Fe³⁺The recognition function of (2) (fig. 10). As shown in FIG. 10, the concentration was 1X 10^-5-1×10^-4In the range of M, with Fe³⁺Increase of concentration, changeThe fluorescence intensity of compound a decreased significantly until quenching.

The compound A-Fe was subsequently explored³⁺Standard curve of the system (FIG. 10, R)²0.99) and limit of detection (LOD 1.2 × 10)^-6mol·L^-1)。

Identification of Fe for further exploration of Compound A³⁺For the reason of (2), a Job's curve is plotted (FIG. 11). As can be seen from FIG. 12, the compounds A and Fe³⁺No stable complex was formed. This is probably due to the O, N heteroatom in compound A being complexed with the B atom first, affecting Fe³⁺Coordination of (3). And the compound A can react with Fe³⁺The reason for the response may be that the V-shaped structure of the TB skeleton forms a semi-cavity, and Fe can be captured³⁺。

Cytotoxicity

Human bronchial epithelial-like (HBE) cells are used as a model, and the cytotoxicity of the compound A on the HBE cells is detected by adopting an MTT method. HBE cells were seeded in 96-well plates (1X 10)^-5one/mL), 100. mu.L of medium was added to each well, CO at 37 ℃₂After 24h incubation in the incubator, different concentrations of compound a were added to the seeded cells and incubated for 24 h. The plates were then washed 3 times with PBS buffer and 10. mu.L of MTT solution was added to each well for an additional 4h incubation. The medium in the wells was removed, 150 μ L of DMSO was added to each well to dissolve the blue-violet formazan (Formazam) crystals in the cells, and the cells were placed on a shaker and shaken at low speed for 5-7min to dissolve the crystalline material thoroughly. Finally, an enzyme-linked immunosorbent assay (ELISA) detector is used for measuring the absorbance values of each well at 560nm and 670 nm. Cytotoxicity was calculated by the following formula:

％viability＝[∑(A_i/A₀×100)/n]

in the formula A_iRespectively the absorbance values of the compounds with different concentrations; a. the₀Mean absorbance values for control wells without added compound; n (═ 3) represents three replicates.

Toxicity of c to HBE cells, normal cells, was tested using the MTT method (figure 12). As shown in fig. 13, compound a has low cytotoxicity to HBE and can be applied to an organism.

As shown in fig. 14, when not illuminated, a549 cells treated with compound a all showed extremely high survival rates, indicating that they had negligible dark toxicity; after the irradiation of light, the survival rate of the A549 cells is obviously reduced. Even if the concentration of 9 is reduced to 6.25. mu. mol. L^-1The survival rate of a549 cells was still less than 40%, indicating that compound a has extremely low dark toxicity and high phototoxicity, and thus it has excellent PDT efficiency.

The half inhibition rate of the compound A on HBE and A549 cells is shown in Table 4, and the result shows that the compound A on the A549 cells has IC after illumination₅₀Has a value less than HBE cells and has a very low IC₅₀Values indicating excellent PDT efficiency and possibility of application to realistic treatment.

TABLE 4 half maximal Inhibitory Concentration (IC) of Compound A on both cells₅₀)

Cell imaging assay

A549 cells are inoculated into a 96 micro-well plate and cultured for 24 h. The cells were subsequently treated with different concentrations (6.25, 12.50. mu. mol. L)^-1) After further incubation for 24h, half of compound A was exposed to light for 2h and half was not exposed to light. The medium was changed to a medium containing calcein (CA, 100. mu.g/mL) for further 24h to stain live and dead cells. The plate was then washed 3 times with PBS buffer and incubated for 4h with MTT solution. The medium was removed and DMSO was added and shaken at low speed for 5-7 min. Finally, the cells were analyzed using fluorescence microscopy.

The in vitro photodynamic therapy effect was directly observed by live/dead cell staining (fig. 15).

As shown in fig. 15, none of the dark groups caused significant cell death, which is indicative of low dark toxicity of compound a; while the cells in the light group were almost all dead, indicating that compound a had better phototoxicity, which is consistent with the results in the experimental analysis of photodynamic therapy in vitro.

Compared with a synthetic raw material and an intermediate, the compound A can clearly image the A549 cells, is yellow in the cells, and can avoid the interference of the background color of the cells. As can be seen from the staining results, compound a can enter the cell and stain the cytoplasm, but not the nucleus.

The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.

Claims

1. A benzothiadiazole-TB-fluoroboron complex characterized by: the structural formula is shown as formula A:

2. a method of synthesizing the benzothiadiazole-TB-fluoroboron complex of claim 1, characterized in that: the method comprises the following steps:

3. use of the benzothiadiazole-TB-fluoroboron complex according to claim 1 as a photosensitizer for photodynamic therapy.

4. Use of the benzothiadiazole-TB-fluoroboron complex according to claim 1 as a fluorescent material in biological imaging.

5. benzothiadiazole-TB-fluoroboron complex as described in claim 1 as Fe³⁺And Cu²⁺The application of the fluorescent probe in metal ion recognition.