Synthesis method of triphenylamine xanthene compound and application of triphenylamine xanthene compound as photocatalytic oxidant

Abstract

The invention provides a synthesis method of a triphenylamine xanthene compound and application of the triphenylamine xanthene compound as a photocatalytic oxidant. Xanthene is taken as an initial raw material, firstly, 4-(diphenylamino) phenylboronic acid is used for reaction in a palladium-catalyzed simple cross-coupling reaction, and an intermediate with an electron donor-acceptor system is synthesized; and carrying out esterification reaction on the intermediate and ethanol under the catalysis of concentrated sulfuric acid to obtain the triphenylamine xanthene compound. The triphenylamine xanthene compound synthesized by the invention has high light capturing ability under visible light, and can catalyze oxygen to generate singlet oxygen and oxidize ABDA. Therefore, the photocatalyst is expected to become a high-efficiency photocatalytic oxidizing agent.

Description

Technical Field

[0001] The invention relates to the technical field of functional organic molecule design, synthesis and application, and in particular to a synthesis method of a triphenylamine xanthene compound and its application as a photocatalytic oxidant. Background Art

[0002] Normally, oxygen exists in triplet form, while singlet oxygen is an excited state that is converted from triplet state by absorbing energy (such as light energy) [Zhao X, Dai Y, Ma F, et al. Chemical Engineering Journal, 2020, 410: 128133.]. Singlet oxygen has significant oxidizing ability and can oxidize 9,10-anthracenediyl-bis(methylene)dicarboxylic acid (ABDA), causing the UV-visible absorption spectrum of ABDA to decrease [Bu Y, Xu T, Zhu X, et al. Chemical science, 2020 (37): 11.].

[0003] After absorbing light of a specific wavelength, photocatalytic oxidants transfer excitation energy to neighboring oxygen through intersystem crossing, converting oxygen from triplet oxygen to singlet oxygen. The currently commonly used method to enhance the efficiency of photocatalytic oxidation is to combine heavy atoms (such as iodine and bromine) to form a heavy atom effect, which can promote spin-orbit coupling and thus improve the ability of intersystem crossing. However, the introduction of heavy atoms often has high biological toxicity and environmental hazards.

[0004] Due to the excellent properties of xanthene and its derivative compounds such as high absorption coefficient, high photostability and long fluorescence emission spectrum wavelength, they have aroused great interest among chemists [Sharifi M, Sharifi A, Abaee MS, et al. Dyes and Pigments, 2024, 221.]. Most studies focus on thermochromic systems and fluorescence imaging [KimI J, Manivannan R, Son Y A. Journal of nanoscience and nanotechnology, 2018, 18(5): 3299-3305. Zhou W, Qiao Q, Tao Y, et al. Sensors and Actuators B: Chemical, 2024, 410: 135691.], but there is little research on the application of photocatalytic oxidation.

[0005] The present invention aims to provide a novel photocatalytic oxidant, which forms an electron donor-acceptor system by forming a triphenylamine xanthene compound through a coupling reaction of triphenylamine and xanthene, thereby improving the generation efficiency of singlet oxygen while maintaining good biocompatibility and environmental friendliness. Summary of the invention

[0006] In order to improve the efficiency of photocatalytic oxidation, the present invention provides a method for synthesizing a triphenylamine xanthene compound and application of the prepared triphenylamine xanthene compound as a photocatalytic oxidant.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] First, the present invention proposes a method for synthesizing a triphenylamine xanthene compound, and the specific synthesis route is:

[0009]

[0010] The preparation method comprises the following steps in sequence:

[0011] Step a: dissolving raw material 1 and compound 2, i.e. 4-(diphenylamino)phenylboronic acid, in an organic solvent, adding K2CO3 and Pd(PPh3)4, and carrying out a simple cross-coupling reaction under alkaline conditions by palladium catalysis to prepare compound 3; wherein the molar ratio of compound 1, compound 2, K2CO3 and Pd(PPh3)4 is 0.8-1.2:2-3:1-1.5:0.1-0.3, the reaction temperature is 100-130°C, and the reaction time is 10-14h;

[0012] Step b: Compound 3 is first dissolved in ethanol, and then concentrated sulfuric acid is added for catalysis, and an esterification reaction occurs in an acidic environment to prepare compound T; wherein the reaction temperature is 80-110° C. and the reaction time is 10-14 h.

[0013] As a preferred technical solution of the present invention, the specific operation of step a is: mixing compound 1 and compound 2 in a three-necked flask, then adding a mixed solvent of toluene and ethanol for ultrasonic dissolution, stirring for 20 to 30 minutes under nitrogen, and then adding K2CO3 and Pd(PPh3)4 to the three-necked flask; placing in an oil bath at 100 to 130°C for reaction for 10 to 14 hours, until TLC spot plate tracking shows that the raw material completely disappears; then, cooling the reaction mixture to room temperature, stopping the reaction, extracting three times with dichloromethane and water, collecting the extract, drying with anhydrous Na2SO4 to remove moisture and evaporating the solvent under reduced pressure, and purifying by silica gel flash chromatography to obtain intermediate product 3.

[0014] As a preferred technical solution of the present invention, the specific operation of step b is: dissolving compound 3 in an ethanol solvent in a three-necked flask and ultrasonically dissolving it; slowly adding concentrated sulfuric acid in a cold water bath, stirring at 80-110° C. for 10-14 h until TLC spot plate tracking shows that the raw material completely disappears; then, after the reaction mixture is cooled to room temperature, the reaction is stopped, and three extractions are performed using dichloromethane and water, the extracts are collected, dried with anhydrous Na2SO4 to remove moisture, and after evaporating the solvent under reduced pressure, the target product T is purified by silica gel flash chromatography.

[0015] Secondly, the present invention also proposes the application of the triphenylamine xanthene compound as a photocatalytic oxidant.

[0016] The triphenylamine xanthene compound prepared by the present invention protects the carboxyl group by esterification, so that the xanthene is ring-opened, its conjugation degree is enhanced, and its absorption of visible light is enhanced. Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1) The triphenylamine xanthene compound prepared by the present invention introduces triphenylamine into the xanthene matrix in a coupling manner to form an electron donor-acceptor system, thereby enhancing the photocatalytic oxidation effect of the compound.

[0018] 2) The triphenylamine xanthene compound of the present invention undergoes an esterification reaction under the catalysis of an acid, thereby enhancing the absorption of the triphenylamine xanthene compound in visible light, so that photocatalytic oxidation can be performed using visible light. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the triphenylamine xanthene compound T prepared in Example 1 1 H NMR spectra.

[0020] Figure 2 is the triphenylamine xanthene compound T prepared in Example 1 13 C NMR spectrum.

[0021] Figure 3 This is the HRMS chart of the triphenylamine xanthene compound T prepared in Example 1.

[0022] Figure 4 It is the UV-visible absorption spectrum of the triphenylamine xanthene compound T prepared in Example 1.

[0023] Figure 5 This is the UV-visible absorption spectrum of the triphenylamine xanthene compound T prepared in Example 1 during the photocatalytic oxidation of ABDA over time.

[0024] Figure 6 This is a kinetic fitting diagram of the photocatalytic oxidation of ABDA by the triphenylamine xanthene compound T prepared in Example 1 over time. DETAILED DESCRIPTION

[0025] Example 1

[0026] A method for synthesizing triphenylamine xanthene is disclosed, and its structure and specific synthesis method are introduced in combination with a synthesis route diagram.

[0027] 1. Synthesis of intermediate 3:

[0028]

[0029] In a three-necked flask, 1 mmol of compound 1 and 2.5 mmol of compound 2, i.e., 4-(diphenylamino)phenylboronic acid, were dissolved in toluene and ethanol organic solvents by ultrasonic dissolution, stirred for 30 min under nitrogen, and then 1.3 mmol of K2CO3 and 0.2 mmol of Pd(PPh3)4 were added, and the mixture was reacted in an oil bath at 120°C for 10 h until TLC spot plate tracking showed that the raw material completely disappeared; then, the reaction mixture was cooled to room temperature, the reaction was stopped, and extraction was performed three times with dichloromethane and water. The extracts were collected, dried with anhydrous Na2SO4 to remove moisture, and the solvent was evaporated under reduced pressure, and then purified by silica gel flash chromatography to obtain intermediate 3 with a yield of 71%.

[0030] Compound 3 1 H NMR (400MHz, CDCl3) δ8.25(d,J=7.56Hz,1H),7.94-7.81(m,2H),7.54-7.47(m,6H),7.43(s,1H),7.37(d,J=7.44Hz 4H),7.28(d,J=7.20Hz,5H),6.89(s,1H),6.83(d,J=8.96Hz,1H),6.92(s,1H),6.60(d,J=8.92Hz,1H), 3.54(t,J=7.08Hz,4H),2.59(s,3H),1.85(t,J=7.08Hz,4H),1.66-1.58(m,4H),1.23(t,J=7.32Hz,6H).

[0031] 2. Synthesis of target product T:

[0032]

[0033] In a three-necked flask, 1 mmol of compound 3 was dissolved in 15 mL of ethanol solvent and dissolved by ultrasonication. 2 mL of 98% concentrated sulfuric acid was slowly added in a cold water bath and stirred at 110 °C for 10 h until TLC spot plate tracking showed that the raw material completely disappeared. Then, the reaction mixture was cooled to room temperature, the reaction was stopped, and extraction was performed three times with dichloromethane and water. The extracts were collected, dried with anhydrous Na2SO4 to remove moisture, and the solvent was evaporated under reduced pressure. Then, the target product T was purified by silica gel flash chromatography with a yield of 92%.

[0034] The target product T 1 H NMR, 13 C NMR, HRMS Figure 1 , 2 , 3, the spectrum analysis is as follows:

[0035] 1 H NMR (400MHz, CDCl3) δ8.31(d,J=7.92Hz,1H),7.85(t,J=7.60Hz,1H),7.77(d,J=7.76Hz 1H),7.74(s,1H),7.42-7.36(m,2H),7.33(s,1H),7.33–7.27(m,4H),7.12(d,J=8.8,4H),7.09-6.97(m,9H),4.08(t,J=4.00Hz,2H),3. 85-3.68(m,4H),2.53(s,1H),1.84-1.69(m,4H),1.56-1.43(m,4H),1.24(t,J=7.12Hz,3H),1.08(t,J=7.12Hz),0.96(t,J=7.24Hz,3H).

[0036] 13 C NMR (100MHz, CDCl3) δ165.07,160.78,159.18,158.74,152.82,148.29,147.78,147.3 5,141.05,133.51,133.11,132.69,131.95,131.55,130.88,130.40,130.10,129.91,1 29.51,128.57,125.03,123.62,122.25,119.88,119.10,118.94,118.37,96.81,62.98,61.79,53.12,52.90,30.62,29.32,22.31,20.34,20.07,15.34,13.96,13.93,13.91.

[0037] HRMS(MALDI-TOF)m / z calcd for C 49 H 49 N2O3 + [M +· ]713.3738,found:713.3746.

[0038] Example 2

[0039] The following uses the triphenylamine xanthene compound T prepared in Example 1 as an example to illustrate its application in the photocatalytic oxidation of ABDA. First, the UV-visible absorption spectrum of T is tested. The specific experimental steps are as follows: T is prepared with N,N-dimethylformamide (DMF) as a solvent at a concentration of 1.0×10 -5 mol / L solution, transfer 3mL of the solution to be tested into a 10mm*10mm four-transparent quartz cuvette, and record the UV-visible absorption curve of the solution to be tested using a UV-visible spectrophotometer.

[0040] Under the irradiation of LED light, T can act as a catalyst to catalyze the production of singlet oxygen. When singlet oxygen is produced in the system, it can cause the continuous oxidation of ABDA, resulting in a rapid decrease in the 377nm UV-visible absorption spectrum of ABDA. The photocatalytic oxidation effect of T is evaluated based on the change in the absorbance of ADBD. The curve of the change of the UV-visible absorption spectrum of ABDA over time is shown in Figure 5 The specific experimental steps are as follows: first, DMF was used as the solvent, and 1x10 -3 mol / L T solution, prepared with dimethyl sulfoxide (DMSO) at 1x10 -3 mol / L ABDA solution. Then add 2mL of deionized water and 20μL of the T solution to be tested into the beaker, stir evenly and transfer the mixed solution into a 10mm*10mm four-transparent quartz cuvette. After baseline correction in the range of 320 to 420nm, immediately add 25μL of ABDA solution. Use a UV-visible spectrophotometer to record the UV-visible absorption curve of the mixed solution as the initial 0-second UV-visible absorption curve. Then place the cuvette at 10mW / cm 2 The UV-visible absorption curve was recorded every 10 seconds. Figure 4 The photocatalytic oxidation effect of T was evaluated by plotting the natural logarithm of the ratio of the absorbance at 377 nm to the initial absorbance within a specific time, ln(A / A0), versus the irradiation time. The experimental data are shown in Figure 6 This indicates that T has excellent photocatalytic oxidation performance.

[0041] It is only an example and explanation of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for synthesizing a triphenylamine xanthene compound, characterized in that: The synthetic route is: The preparation method comprises the following steps in sequence: Step a: dissolving raw material 1 and compound 2, i.e. 4-(diphenylamino)phenylboronic acid, in an organic solvent, adding K2CO3 and Pd(PPh3)4, and carrying out a simple cross-coupling reaction under alkaline conditions by palladium catalysis to prepare compound 3; wherein the molar ratio of compound 1, compound 2, K2CO3 and Pd(PPh3)4 is 0.8-1.2:2-3:1-1.5:0.1-0.3, the reaction temperature is 100-130°C, and the reaction time is 10-14h; Step b: Compound 3 is first dissolved in ethanol, and then concentrated sulfuric acid is added for catalysis, and an esterification reaction occurs in an acidic environment to prepare compound T; wherein the reaction temperature is 80-110° C. and the reaction time is 10-14 h.

2. The synthesis method according to claim 1, characterized in that The specific operation of step a is as follows: mixing compound 1 and compound 2 in a three-necked flask, then adding a mixed solvent of toluene and ethanol for ultrasonic dissolution, stirring for 20 to 30 minutes under nitrogen, and then adding K2CO3 and Pd(PPh3)4 into the three-necked flask; reacting in an oil bath at 100 to 130°C for 10 to 14 hours until TLC spot plate tracking shows that the raw material completely disappears; then, cooling the reaction mixture to room temperature, stopping the reaction, extracting three times with dichloromethane and water, collecting the extract, drying with anhydrous Na2SO4 to remove moisture, evaporating the solvent under reduced pressure, and purifying by silica gel flash chromatography to obtain intermediate product 3.

3. The synthesis method according to claim 1, characterized in that The specific operation of step b is as follows: dissolving compound 3 in an ethanol solvent in a three-necked flask and ultrasonically dissolving the compound; slowly adding concentrated sulfuric acid in a cold water bath, stirring at 80-110° C. for 10-14 h until TLC spot plate tracking shows that the raw material completely disappears; then, cooling the reaction mixture to room temperature, stopping the reaction, extracting the mixture three times with dichloromethane and water, collecting the extract, drying the extract with anhydrous Na2SO4 to remove moisture, evaporating the solvent under reduced pressure, and purifying the target product T by silica gel flash chromatography.

4. Use of the triphenylamine xanthene compound synthesized by the method according to any one of claims 1 to 3 as a photocatalytic oxidant.

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