Copper-based photosensitizer as well as preparation method and application thereof

Abstract

The invention provides a phenyl phosphonic acid bis (o-isocyano-phenol) ester ligand which is prepared by the following steps: in an inert gas atmosphere, mixing a compound benzoxazole with anhydrous tetrahydrofuran, cooling to-95 to-65 DEG C, adding an n-butyllithium solution dissolved in an organic solvent, stirring at-95 to-65 DEG C for 0.5-4 hours, adding diphenylphosphoryl chloride, stirring at room temperature for 8-10 hours, filtering, washing, and drying to obtain the phenyl phosphonic acid bis (o-isocyano-phenol) ester ligand. Carrying out post-treatment on the obtained reaction liquid to obtain a phenyl phosphonic acid bis (o-isocyano phenol) ester ligand; compared with the most common organic dye photosensitizer, the copper-based photosensitizer prepared from the phenyl phosphonic acid bis (o-isocyano-phenol) ester ligand overcomes the defect that the catalytic activity of the organic dye photosensitizer is rapidly reduced under long-term illumination, and in addition, the organic dye photosensitizer is easy to generate an aggregation-induced quenching effect; the photosensitizer disclosed by the invention does not generate an aggregation-induced quenching effect; compared with an iridium complex photosensitizer which is commonly used at present, the cuprous photosensitizer provided by the invention is more environment-friendly.

Description

Technical Field

[0001] This invention relates to the fields of organic compound synthesis and catalyst technology, and in particular to a method for synthesizing a phenylphosphonic acid bis(o-isocyanophenol) ester ligand, and also to a method for preparing a monovalent copper photocatalyst from the ligand. Background Technology

[0002] Over the past two decades, metal complexes have been used as photocatalysts. These complexes effectively "transfer" the short-wavelength energy of visible light from sunlight to small organic molecules, thereby enabling the formation of various valence bonds within and between these molecules. Meanwhile, chemists have developed a series of Ru(II) and Ir(III) organometallic complexes, exhibiting strong absorption capacity, long excited-state lifetimes, and strong photo-oxidation-reduction capabilities. These photocatalysts also possess strong photostability and have been successfully applied to various small organic molecule reactions. However, these photocatalysts have several drawbacks. For example, their central metals are precious metals, which are harmful to the environment. Furthermore, the skeletal characteristics of metal complexes prevent them from linking with asymmetric ligands, limiting their industrial application. For instance, the European Journal of Organic Chemistry (2022), 2022(18), e202200158 proposes a scheme requiring the use of orthogonal sulfur, which is highly toxic.

[0003] Compared to the most commonly used organic dye photosensitizers, this invention overcomes the drawback of the rapid decline in catalytic activity of organic dye photosensitizers under long-term light exposure. The chromophores of traditional organic dyes (such as azo and anthraquinone structures) have relatively low chemical bond energies, making them prone to irreversible photochemical reactions such as bond breaking and oxidation under continuous light exposure, leading to rapid "photobleaching." Furthermore, organic dye photosensitizers are prone to aggregation-induced quenching (ACQ) effects. ACQ is a common problem for many traditional organic dyes; when they are at high concentrations in solution or aggregate in the solid state, the molecules are tightly packed, causing excited-state energy to dissipate as heat, significantly reducing fluorescence and the ability to generate singlet oxygen. This severely limits their effectiveness in practical scenarios requiring high concentrations. The photosensitizer of this invention does not exhibit the ACQ effect.

[0004] Compared to the commonly used iridium complex photosensitizers, trivalent and tetravalent iridium salts are environmentally polluting. Iridium is one of the rarest elements in the Earth's crust, and its scarcity and high cost limit its large-scale application. Furthermore, the potential long-term toxicity of iridium complexes in organisms is also a barrier to their application in the biomedical field. In contrast, monovalent copper salts do not pollute the environment. Monovalent copper is abundant in the Earth's crust, making it inexpensive and an essential trace element for organisms. Its environmental compatibility and biosafety are far superior to iridium. Using monovalent copper is a key step in realizing the greening and democratization of photosensitizer technology, and the monovalent copper photosensitizer provided by this invention is more environmentally friendly.

[0005] Compared to the more commonly used ruthenium complex photosensitizers, divalent ruthenium salts are environmentally polluting, as these heavy metals themselves possess certain biological and environmental toxicity. Their production, use, and waste disposal may pose environmental and safety risks, contradicting the principles of green chemistry. Furthermore, ruthenium resources are extremely scarce. Ruthenium, along with its equally important iridium (Ir), are platinum group metals found in very low amounts in the Earth's crust, classifying them as rare metals. This results in expensive raw materials and a supply susceptible to geopolitical and market fluctuations, making them unsuitable for large-scale industrial applications.

[0006] Copper-based photosensitizers possess excellent ligand regulation capabilities. Therefore, ligand regulation is a key aspect of their development. This invention introduces a trifluoromethyl group to achieve an excited-state oxidation potential comparable to cyano-carbazole photosensitizers, while maintaining a reduction potential similar to that of currently reported phosphorus / nitrogen heteroligand photosensitizers. However, current copper-based photosensitizers still suffer from several drawbacks, such as short excited-state lifetimes, complex preparation processes, strong hydrophobicity, and narrow absorption bands (primarily absorbing only blue and green light). These problems urgently need to be addressed. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for synthesizing phenylphosphonic acid bis(o-isocyanophenol) ester ligands and their copper complexes.

[0008] The technical problem to be solved by the present invention is to change the excited state lifetime and excited state redox potential of copper-based photosensitizers by regulating the functional groups coordinated with copper, and at the same time change the functional groups on the o-phenanthroline skeleton, thereby utilizing the inductive effect to further regulate the excited state properties of the photosensitizers.

[0009] The technical solution of the present invention is as follows: This invention provides a copper-based photosensitizer as shown in Formula D (complex D-diCF3, complex Dpt-Bu, complex D-Ph, complex DH).

[0010] In formula D, the two Ar groups are identical and are independently selected from 3,5-bis(trifluoromethyl)phenyl, 4-tert-butylphenyl, phenyl or hydrogen atom.

[0011] Further, the preparation method is as follows: Under an inert gas atmosphere (preferably argon) and under light-protected conditions, the phenylphosphonic acid bis(o-isocyanophenol) ester ligand as shown in Formula B and compound C (2,9-dimethyl-4,7-diaryl-1,10-phenanthroline) are dissolved in dry dichloromethane, and then copper tetrafluoroborate tetraacetonitrile is added. The mixture is stirred at 20-40°C (preferably 25°C) for 2-6 hours (preferably 3 hours) to obtain a reaction solution. The reaction solution is then added to solvent A. The product precipitates, the solvent is removed by filtration, and the resulting filter cake is washed with solvent A to obtain the copper-based photosensitizer; solvent A is n-hexane or diethyl ether; the molar ratio of copper tetrafluoroborate tetraacetonitrile, phenylphosphonic acid bis(o-isocyanophenol) ester ligand, and compound C is 1:1-1.2:1-1.2 (preferably 1:1:1); the volume of dichloromethane, based on the molar amount of copper tetrafluoroborate tetraacetonitrile, is 100-250 mL / mmol (preferably 200 mL / mmol); compound C is selected from 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (C-Ph, commercially available), 2,9-dimethyl-1,10-phenanthroline (CH, commercially available), C-diCF3, or Cpt-Bu; .

[0012] Furthermore, the preparation method of the phenylphosphonic acid bis(o-isocyanophenol) ester ligand as shown in Formula B is as follows: Under an inert gas atmosphere (preferably argon), compound A (benzoxazole) is mixed with anhydrous tetrahydrofuran, cooled to -95 to -65°C (preferably -78°C), and a solution of n-butyllithium dissolved in an organic solvent (preferably n-hexane) is added. The mixture is stirred at -95 to -65°C (preferably -78°C) for 0.5 to 4 hours (preferably 1 hour), and then diphenylphosphine chloride is added. The mixture is stirred at room temperature for another 8 to 10 hours. The resulting reaction solution is post-treated to obtain the phenylphosphonic acid bis(o-isocyanophenol) ester ligand as shown in Formula B. The molar ratio of compound A, n-butyllithium, and diphenylphosphine chloride is 1:0.55-1.25:0.20-0.75 (preferably 1:1.05:0.53).

[0013]

[0014] Furthermore, the volume of the anhydrous tetrahydrofuran is 1-7.5 (preferably 2.5 ml / mmol) based on the amount of substance of compound A.

[0015] Further, the post-treatment is as follows: a mixed solution of saturated sodium bicarbonate solution and methyl tert-butyl ether at a volume ratio of 1:2-3 at 0°C is added to the reaction solution for quenching and extraction. The organic phase is taken, dried with anhydrous sodium sulfate, and concentrated by rotary evaporation. The obtained sample is separated by a 100-200 mesh silica gel column to obtain a crude product. The crude product is dissolved in hot acetonitrile solution for recrystallization to obtain the phenylphosphonic acid bis(o-isocyanophenol) ester ligand.

[0016] Furthermore, the preparation method of the C-diCF3 is as follows: (1) Under an argon atmosphere, mix McFarland acid and trimethyl orthoacetate, stir and reflux at 50-120°C (preferably 105°C) for 0.25-3 hours (preferably 1 hour), lower the temperature to 50-90°C (preferably 80°C), add o-phenylenediamine, stir and reflux at 50-120°C (preferably 105°C) for 0.25-3 hours (preferably 1 hour), lower the temperature to room temperature, and continue stirring for 6-18 hours (preferably 12 hours). After the reaction is complete, filter the resulting mixture and wash the filter cake with methyl tert-butyl ether to obtain intermediate G; the molar ratio of McFarland acid to o-phenylenediamine is 2.0-4.0:1 (preferably 2.3:1), and the volume of trimethyl orthoacetate is 1-3 mL / mmol (preferably 1.8 mL / mmol) based on the molar amount of o-phenylenediamine. (2) Under an argon atmosphere, the intermediate G described in step (1) is mixed with diphenyl ether and stirred at 180-255°C (preferably 250°C) for 0.25-4 hours (preferably 2 hours). After cooling to 45-90°C (preferably 70°C), the mixture is filtered. The resulting filter cake is washed sequentially with acetone, n-hexane, and methyl tert-butyl ether to obtain intermediate H. The volume of the diphenyl ether, based on the amount of intermediate G, is 5-20 mL / mmol (preferably 12.5 mL / mmol). (3) Under an argon atmosphere, intermediate H and phosphorus oxybromide described in step (2) are mixed and stirred at 75-130°C (preferably 105°C) for 2-8 hours (preferably 6 hours). After the reaction is completed, the mixture is cooled to room temperature, and the resulting reaction solution is added to an ice-water mixture and stirred for 0.5-3 hours (preferably 1 hour). Then dichloromethane is added, and potassium hydroxide is added to adjust the pH to 13-14. The organic phases are separated and combined, and the solvent is removed under vacuum. The mixture is separated by column chromatography, using a mixture of methanol and dichloromethane (volume ratio of 1:25) as the eluent. The eluent containing the target product is collected and evaporated to dryness to obtain intermediate I. The molar ratio of intermediate H to phosphorus oxybromide is 1:5-30 (preferably 1:25). (4) Under an argon atmosphere, the intermediate I, alkaline substance (preferably sodium carbonate), palladium catalyst (preferably tetra(triphenylphosphine)palladium), and 3,5-bis(trifluoromethyl)phenylboronic acid described in step (3) are dissolved in a mixed solvent of 1,4-dioxane and deionized water (preferably a volume ratio of 1,4-dioxane to water of 3:1). After stirring and refluxing at 70-140°C (preferably 130°C) for 12-48 hours (preferably 24 hours), the reaction temperature is lowered to room temperature. The solvent is removed by vacuum distillation under vacuum conditions, followed by extraction with dichloromethane. The organic phases are combined and collected under vacuum. The solvent was removed under certain conditions, and the product was separated by column chromatography using a mixed solvent of ethanol and ethyl acetate (volume ratio 1:50) as the eluent. The eluent containing the target product was collected and evaporated to dryness to obtain compound C-diCF3. The molar ratio of intermediate I, 3,5-bis(trifluoromethyl)phenylboronic acid, palladium catalyst, and basic substance was 1:2-6:0.05-0.3:5-30 (preferably 1:4:0.1:20). The volume of the mixed solvent of 1,4-dioxane and deionized water was 50 mL / mmol based on the molar amount of intermediate I.

[0017]

[0018] Furthermore, the preparation method of the Cpt-Bu is as follows: Under an argon atmosphere, intermediate I, 4-tert-butylphenylboronic acid, a basic substance (preferably cesium carbonate), a palladium catalyst (preferably tris(benzylacetone)palladium), a phosphine ligand (preferably tricyclohexylphosphine), 1,4-dioxane, and deionized water (preferably a volume ratio of 1,4-dioxane to water of 2.5:1, with a total volume of 1,4-dioxane and water of 17.5 mL / mmol based on the molar amount of intermediate I) are added sequentially. After stirring and refluxing at 60-130°C (preferably 100°C) for 2-12 hours (preferably 6 hours), the reaction temperature is lowered to room temperature. The solvent was removed under vacuum, followed by extraction with dichloromethane. The organic phases were combined and collected. The solvent was removed under vacuum, and the mixture was separated by column chromatography using a mixed solvent of ethanol and ethyl acetate (volume ratio 1:50) as the eluent. The eluent containing the target product was collected and evaporated to dryness to obtain compound Cpt-Bu. The molar ratio of intermediate I, 4-tert-butylphenylboronic acid, basic substance, palladium catalyst and phosphine ligand is 1:2-8:2-9:0.02-0.2:0.03-0.3 (preferably 1:4:4.5:0.05:0.12).

[0019] This invention also provides an intermediate for preparing copper-based photosensitizers, such as the phenylphosphonic acid bis(o-isocyanophenol) ester ligand shown in Formula B. .

[0020] This invention also provides the application of a copper-based photosensitizer in the catalytic oxidation reaction of methylenequinone compounds.

[0021] Furthermore, the process should involve: under alkaline conditions, organic solvents, and visible light irradiation, using the copper-based photosensitizer as a catalyst, catalyzing the oxidation reaction of methylene quinone compounds and proline derivatives to generate benzophenone compounds.

[0022] The technical effects of this invention are as follows: Compared to the most commonly used organic dye photosensitizers, this invention overcomes the disadvantage that the catalytic activity of organic dye photosensitizers decreases rapidly under long-term light exposure. In addition, organic dye photosensitizers are prone to aggregation-induced quenching (ACQ) effect, while the photosensitizer of this invention does not exhibit the ACQ effect.

[0023] Compared to commonly used iridium complex photosensitizers, trivalent and tetravalent iridium salts are environmentally polluting, while monovalent copper salts are not. The monovalent copper photosensitizer provided by this invention is more environmentally friendly.

[0024] By designing a novel ligand containing phosphonate and isocyanophenol structures and coordinating it with a monovalent copper salt, the performance of the photosensitizer can be synergistically regulated at both the coordination environment and skeletal electronic effects levels—demonstrating clear innovation and application potential. This aligns closely with the current trend in academia and industry to develop low-cost, high-efficiency, and tunable copper-based photosensitizers. Attached Figure Description

[0025] Figure 1 The results of normalized UV-Vis absorption and normalized fluorescence emission spectra of complex D-diCF3 in Example 2.

[0026] Figure 2 Results of cyclic voltammetry tests on complex D-diCF3 in Example 2.

[0027] Figure 3 The results of normalized UV-Vis absorption and normalized fluorescence emission spectra of the complex Dpt-Bu in Example 3.

[0028] Figure 4 : Cyclic voltammetry test results of complex Dpt-Bu in Example 3.

[0029] Figure 5 The results of normalized UV-Vis absorption and normalized fluorescence emission spectra of complex D-Ph in Example 4.

[0030] Figure 6 : Cyclic voltammetry test results of complex D-Ph in Example 4.

[0031] Figure 7 The results of normalized UV-Vis absorption and normalized fluorescence emission spectra of the complex DH in Example 5.

[0032] Figure 8 Results of cyclic voltammetry tests on complex DH in Example 5.

[0033] Figure 9 The results of normalized UV-Vis absorption and normalized fluorescence emission spectra of the complex P-diIPR in Example 9.

[0034] Figure 10 : Cyclic voltammetry test results of complex P-diIPR in Example 9.

[0035] Figure 11 The results of normalized UV-Vis absorption and normalized fluorescence emission spectra of the complex P-diSBU in Example 10.

[0036] Figure 12 Cyclic voltammetry test results of complex P-diSBU in Example 10. Detailed Implementation

[0037] The present invention is further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0038] Example 1: Preparation of bis(o-isocyanophenol) phenylphosphonate B

[0039] Add 1.905 g (16.0 mmol) of benzoxazole to a two- (three-necked) flask and add a magnetic stir bar. Add a three-way balloon to the apparatus, purge with argon gas, and circulate the gas three times. Inject 40 mL of freshly distilled anhydrous tetrahydrofuran. After injection, move the flask to -78°C for complete cooling. Then, use a syringe to measure 6.72 mL (1.05 equiv.) of a 2.5 M n-butyllithium solution in n-hexane and add it dropwise to the flask. The solution color gradually changes from pale yellow and transparent to purplish-red and opaque, indicating the gradual formation of lithium salt. Maintain the temperature at -78°C and stir for 1 hour. Next, use a syringe to measure 1.20 mL (8.48 mmol) of diphenylphosphine chloride and add it dropwise at -78°C. After addition, move the flask to room temperature and stir for 9 hours to obtain the reaction solution. During this process, the color of the reaction solution gradually changes from purplish-red to orange-red and transparent.

[0040] After the reaction was complete, the reaction solution was poured into a mixture of saturated sodium bicarbonate solution and methyl tert-butyl ether (20 mL saturated sodium bicarbonate solution, 60 mL methyl tert-butyl ether) at 0°C for extraction and quenching. The organic phase was then separated using a separatory funnel, dried with anhydrous sodium sulfate, filtered to remove sodium sulfate, and the filtrate was evaporated by rotary evaporation to remove the solvent. The filtrate was then loaded onto a 100-200 mesh silica gel column. Compound B showed a positive reaction (R) when developed in a mixture of petroleum ether and ethyl acetate on silica gel thin-layer chromatography (TLC). f =0.66, therefore, the byproduct was eluted using a 4:1 volume ratio of petroleum ether to ethyl acetate, and then the crude compound B was eluted using a 1:1 volume ratio of petroleum ether to ethyl acetate. The eluents containing the crude product were combined, and the solvent was removed by rotary evaporation to obtain the crude compound B. A hot acetonitrile solution of the crude product was prepared at approximately 45°C (the temperature should not be too high, otherwise it will decompose completely), and then cooled to room temperature. After recrystallization, high-purity ligand B was obtained.

[0041] Characterization of ligand B (phenylphosphonic acid bis(o-isocyanophenol) ester ligand): 1 H-NMR (500 MHz, Chloroform- d ) δ 8.05 – 7.96 (m, 2H), 7.66 – 7.60 (m,1H), 7.60 – 7.52 (m, 4H), 7.33 (td, J = 7.1, 1.3 Hz, 2H), 6.40 – 6.32 (m,4H). 13 C NMR (125 MHz, Chloroform- d ) δ 167.47, 150.19, 133.71, 132.61,132.32, 129.08, 128.99, 125.55, 122.21, 119.01, 117.02. The synthesis reaction formula is as follows:

[0042] The ligands used in Example 1 for monovalent copper photocatalysts are rarely reported. Their innovation is demonstrated by Examples 2-10, which are detailed in Examples 2-10 of this invention. Example 2: Preparation method of copper-based photosensitizer {[2,9-dimethyl-4,7-(3,5-bis(trifluoromethylphenyl)-1,10-phenanthroline][bis(o-isocyanophenol) phenylphosphonate]} copper tetrafluoroborate (I) (complex D-diCF3):

[0043] First, add McFarland acid (9.944 g, 69.0 mmol) to a 250 mL three-necked flask equipped with a condenser. Replace the flask with argon gas three times, then add trimethyl orthoacetate (53.4 mL). Stir and reflux at 105 °C for 1 hour. Lower the temperature to 80 °C, then add o-phenylenediamine (3.24 g, 30.0 mmol). Continue stirring and reflux at 105 °C for 1 hour, then lower the temperature to room temperature and continue stirring for 12 hours. After 12 hours of reaction, stop stirring. Filter the resulting mixture under reduced pressure. Wash the filter cake three times with methyl tert-butyl ether (total volume 200 mL). The filter cake yields intermediate G, a white solid, with a yield of 7.992 g and a yield of 60% (yield calculated using the formula: yield = ...). (The same applies below)

[0044]

[0045] Step 2: Intermediate G (4.44 g, 10.0 mmol) was added to a 250 mL three-necked flask, the argon gas was purged three times, and diphenyl ether (125.0 mL) was added. The reaction was then heated to 220 °C and stirred for 2 hours. After cooling to 70 °C, the mixture was filtered and washed successively with 50 mL acetone, 50 mL n-hexane, and 50 mL methyl tert-butyl ether to obtain intermediate H, a light brown solid with a yield of 2.16 g and a yield of 90%.

[0046]

[0047] Step 3: Add intermediate H (1.815 g, 5.0 mmol) and phosphorus oxybromide (35.75 g, 125 mmol) to a three-necked flask. Install the balloon-three-way stopcock device and perform nitrogen purging three times. Stir the reaction at 105°C for 6 hours. After the reaction is complete, cool to room temperature and slowly pour the reaction solution into a mixture of 100 mL of ice and water. Continue stirring at room temperature for 1 hour. Then, add 100 mL of dichloromethane and adjust the pH to 13-14 with potassium hydroxide granules. Maintain 0°C during neutralization to prevent dichloromethane from boiling. Stir the resulting liquid using a magnetic stirrer (standard procedure for large-volume extraction). Pour the resulting liquid into a separatory funnel to separate the organic phase. Extract twice with dichloromethane (100 mL each time, total volume 200 mL). The organic phases were combined (mL), the solvent was removed under vacuum, and the mixture was separated by column chromatography using a 1:25 (v / v) mixture of methanol and dichloromethane as the eluent (50 mL of methanol and 1.25 L of dichloromethane throughout the column chromatography). The eluent containing the target product was collected, and the solvent was removed by rotary evaporation to obtain intermediate I, a light brown solid, with a yield of 1.22 g and a yield of 67%.

[0048] Step 4 (Synthesis of compound C-diCF3): Intermediate I (0.73 g, 2.0 mmol), sodium carbonate (4.24 g, 40.0 mmol), tetra(triphenylphosphine)palladium (0.23 g, 0.2 mmol), and 3,5-bis(trifluoromethyl)phenylboronic acid (2.06 g, 8.0 mmol) were added sequentially to a 250 mL three-necked flask. Argon gas was purged three times. 75 mL of 1,4-dioxane and 25 mL of deionized water were added. The mixture was stirred and refluxed at 130 °C for 24 hours. The reaction temperature was then lowered to room temperature, and the solvent was removed under vacuum. The mixture was then extracted with dichloromethane. The organic phases were combined and the solvent removed under vacuum. Separation was performed by column chromatography using a 1:50 mixture of ethanol and ethyl acetate as the eluent. Ethanol was used in 20 mL of dichloromethane throughout the column chromatography process. mL of ethyl acetate was added, and the eluent containing the target product was collected. The solvent was removed by rotary evaporation to obtain compound C-diCF3, a light brown solid, with a yield of 0.76 g and a yield of 60%.

[0049]

[0050] NMR characterization data of ligand C-diCF3: 1 H NMR (500 MHz, Chloroform- d ) δ 8.12 (t, J= 2.3 Hz, 2H), 7.97 (d, J = 2.2 Hz, 4H), 7.76 (s, 2H), 7.47 (s, 2H), 2.96 (s, 6H).

[0051] 13 C NMR (125 MHz, Chloroform- d ) δ 157.71, 144.87, 142.57, 138.18 –137.38 (m), 130.06 (dd, J = 32.2, 7.4 Hz), 127.38, 127.25, 126.48 (q, J = 4.4Hz), 125.08, 123.78 (p, J = 4.3 Hz), 123.59, 122.90, 121.89, 120.73, 25.88.

[0052] Step 5 (Synthesis of Complex D-diCF3): Compound C-diCF3 (158.0 mg, 0.25 mmol) and compound B (bis(o-isocyanophenol) ester ligand of phenylphosphonic acid) (90.0 mg, 0.25 mmol) were added to a 100 mL three-necked flask. The mixture was then purged three times with argon gas, followed by the addition of 50 mL of dry dichloromethane. The mixture was stirred until the solid was completely dissolved, and the flask was wrapped with aluminum foil to protect it from light. Copper tetrafluoroborate tetraacetonitrile (78.5 mg, 0.25 mmol) was then added under an argon gas flow, and the mixture was stirred at approximately 25 °C for 3 hours. After the reaction was complete, the reaction solution was concentrated to the volume of a just-saturated solution. This solution was then aspirated and added dropwise to n-hexane under stirring (125 mL). The product precipitated, and the solvent was removed by filtration. The filter cake was washed with n-hexane. The washed filter cake was complex D-diCF3, with a yield of 285.75 mg, or 100%. The synthesis method of ligand B (phenylphosphonic acid bis(o-isocyanophenol) ester ligand) is the same as in Example 1. The synthesis route in this embodiment is as follows:

[0053] The normalized UV-Vis spectral analysis results of the complex D-diCF3 are shown in the figure. Figure 1 Extrapolation yielded an excited-state wavelength of 394 nm.

[0054] The cyclic voltammetry results of the complex D-diCF3 are shown in the figure. Figure 2 .

[0055] Cyclic voltammetry of the D-diCF3 complex: A solution of the copper complex (0.0005 M) was tested using 0.05 M Bu4NBF4 as the supporting electrolyte. The solution was degassed with argon for 20 minutes prior to measurement. Cyclic voltammetry scans were performed at 50 mV. -1 The scan rate was performed three times.

[0056] The triplet state energy was calculated using the value obtained by intersecting the absorption and emission spectra of the copper complex:

[0057] Data converted to saturated calomel electrode (SCE) as a control:

[0058] from Figure 1 and Figure 2 As can be seen from the data filled in the table above, E 1 / 2 (Cu I / Cu 0 The excited-state oxidation potential of D-diCF3 prepared in this embodiment is +1.54 V (the reference electrode is a saturated calomel electrode), while the excited-state oxidation potential of most copper-based photocatalysts is only +1.00 V. This embodiment shows a significant improvement in the excited-state oxidation potential, which makes up for the deficiency of the weak excited-state oxidation of copper-based photocatalysts.

[0059] Example 3

[0060] Preparation method of copper-based photosensitizer {[2,9-dimethyl-4,7-(4'-tert-butylphenyl)-1,10-phenanthroline][bis(o-isocyanophenol) phenylphosphonate]} copper tetrafluoroborate (I) (complex Dpt-Bu): First, McFarland acid (9.944 g, 69.0 mmol) was added to a 250 mL three-necked flask equipped with a condenser. Argon gas was purged three times, followed by the addition of trimethyl orthoacetate (53.4 mL). The mixture was stirred and refluxed at 105 °C for 1 hour. The temperature was then lowered to 80 °C, and o-phenylenediamine (3.24 g, 30.0 mmol) was added. The mixture was stirred and refluxed at 105 °C for another hour, then cooled to room temperature and stirred for another 12 hours. After 12 hours of reaction, stirring was stopped, and the resulting mixture was filtered under reduced pressure. The filter cake was washed three times with methyl tert-butyl ether (total volume 200 mL) to obtain intermediate G, a white solid, with a yield of 7.992 g (60%).

[0061] Step 2: Intermediate G (4.44 g, 10.0 mmol) was added to a 250 mL three-necked flask, the argon gas was purged three times, and diphenyl ether (125.0 mL) was added. The reaction was then heated to 220 °C and stirred for 2 hours. After cooling to 70 °C, the mixture was filtered and washed successively with 50 mL acetone, 50 mL n-hexane, and 50 mL methyl tert-butyl ether to obtain intermediate H, a light brown solid with a yield of 2.16 g and a yield of 90%.

[0062]

[0063] Step 3: Add intermediate H (1.815 g, 5.0 mmol) and phosphorus oxybromide (35.75 g, 125 mmol) to a three-necked flask. Install the balloon-three-way stopcock device and perform nitrogen purging three times. Stir the reaction at 105°C for 6 hours. After the reaction is complete, cool to room temperature and slowly pour the reaction solution into a mixture of 100 mL of ice and water. Continue stirring at room temperature for 1 hour. Then, add 100 mL of dichloromethane and adjust the pH to 13-14 with potassium hydroxide granules. Maintain 0°C during neutralization to prevent dichloromethane from boiling. Stir the resulting liquid using a magnetic stirrer (standard procedure for large-volume extraction). Pour the resulting liquid into a separatory funnel to separate the organic phase. Extract twice with dichloromethane (100 mL each time, total volume 200 mL). The organic phases were combined (mL), the solvent was removed under vacuum, and the mixture was separated by column chromatography using a 1:25 (v / v) mixture of methanol and dichloromethane as the eluent (50 mL of methanol and 1.25 L of dichloromethane throughout the column chromatography). The eluent containing the target product was collected, and the solvent was removed by rotary evaporation to obtain intermediate I, a light brown solid, with a yield of 1.22 g and a yield of 67%.

[0064] Step 4 (Synthesis of compound Cpt-Bu): Intermediate I (0.73 g, 2.0 mmol) 4-tert-butylphenylboronic acid (1.42 g, 8.0 mmol), cesium carbonate (5.52 g, 9.0 mmol), tris(benzylacetone)palladium (0.09 g, 0.1 mmol), and tricyclohexylphosphine (67.3032 mg, 0.24 mmol) were added sequentially to a 100 mL three-necked flask. The flask was purged with argon gas three times. Then, 25 mL of 1,4-dioxane and 10 mL of... Deionized water was stirred and refluxed at 100°C for 6 hours. The reaction temperature was then lowered to room temperature, the solvent was removed under vacuum, and the mixture was extracted with dichloromethane. The organic phases were combined and collected, the solvent was removed under vacuum, and the mixture was separated by column chromatography using a mixed solvent of ethanol and ethyl acetate at a volume ratio of 1:50 (20 mL ethanol, 1 L ethyl acetate). The eluent containing the target product was collected and evaporated to dryness to give compound Cpt-Bu, a light brown solid, with a yield of 0.75 g and a yield of 80%.

[0065] Nuclear magnetic resonance characterization of compound Cpt-Bu: 1 H NMR (500 MHz, Chloroform- d ) δ 7.85 –7.73 (m, 6H), 7.47 (s, 2H), 7.36 – 7.20 (m, 4H), 2.96 (s, 6H), 1.33 (s, 18H). 13 C NMR (125 MHz, Chloroform- d ) δ 158.06, 152.68, 145.09, 143.32, 136.17,129.52, 127.69, 125.50, 123.55, 121.93, 34.94, 31.17, 25.88.

[0066] Step 5 (Synthesis of complex Dpt-Bu): Compound Cpt-Bu (118.0 mg, 0.25 mmol) and compound B (90.0 mg, 0.25 mmol) were added to a 100 mL three-necked flask. The mixture was then purged three times with argon gas, followed by the addition of 50 mL of dry dichloromethane. The mixture was stirred until the solid was completely dissolved, and the flask was wrapped with aluminum foil to protect it from light. Copper tetrafluoroborate tetraacetonitrile (78.5 mg, 0.25 mmol) was then added under an argon gas flow, and the mixture was stirred at approximately 25 °C for 3 hours. After the reaction was complete, the reaction solution was concentrated to the volume of a just-saturated solution. This solution was then aspirated and added dropwise to 125 mL of hexane under stirring. The product precipitated, and the solvent was removed by filtration. The filter cake was washed three times with 30 mL of hexane. The washed filter cake was the complex Dpt-Bu, with a yield of 245.572 mg, or 100%. The synthesis method of ligand B (phenylphosphonic acid bis(o-isocyanophenol) ester ligand) is the same as in Example 1. The synthesis route is as follows:

[0067] The normalized UV-Vis spectral analysis results of the complex Dpt-Bu are shown in the figure. Figure 3 Extrapolation yielded an excited-state wavelength of 391 nm.

[0068] The cyclic voltammetry results of the complex Dpt-Bu are shown in the table below. Figure 4 .

[0069] Cyclic voltammetry of the Dpt-Bu complex: A solution of the copper complex (0.0005 M) was tested using 0.05 M Bu₄NBF₄ as the supporting electrolyte. The solution was degassed with argon for 20 minutes prior to measurement. Cyclic voltammetry scans were performed at 50 mV. -1 The scan rate was performed three times.

[0070] Based on previous literature, the triplet state energy was calculated using the value obtained by intersecting the absorption and emission spectra of copper complexes:

[0071] Data converted to saturated calomel electrode (SCE) as a control:

[0072] from Figure 3 and Figure 4 As can be seen from the data filled in the table above, E 1 / 2 (Cu I / Cu 0 The excited-state oxidation potential of the Dpt-Bu prepared in this embodiment is +1.29 V (the reference electrode is a saturated calomel electrode), while the excited-state oxidation potential of most copper-based photocatalysts is only +1.00 V. This embodiment shows a significant improvement in the excited-state oxidation potential, thus compensating for the weakness of the excited-state oxidation potential of copper-based photocatalysts.

[0073] Example 4

[0074] Synthesis of copper-based photosensitizer {[2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline][bis(o-isocyanophenol) phenylphosphonate]} copper tetrafluoroborate (I) (complex D-Ph):

[0075] Preparation of complex D-Ph: Compound C-Ph (90.0 mg, 0.25 mmol, purchased from Accela Technology Co., Ltd., trade name: Bath Copper) and compound B (90.0 mg, 0.25 mmol) were added to a 100 mL three-necked flask. The mixture was then purged three times with argon gas, followed by the addition of 50 mL of dry dichloromethane. The mixture was stirred until the solid was completely dissolved, and the flask was wrapped with aluminum foil to protect it from light. Copper tetrafluoroborate tetraacetonitrile (78.5 mg, 0.25 mmol) was then added under an argon gas flow. The mixture was stirred at approximately 25 °C for 3 hours to obtain the reaction solution. After the reaction was complete, the reaction solution was concentrated to the volume of a just-saturated solution, and then added dropwise to 125 mL of n-hexane while stirring. The product precipitated, and the solvent was removed by filtration. The filter cake was washed three times with 30 mL of n-hexane. The filter cake was complex D-Ph, with a yield of 217.53 mg, or 100%. The synthesis method of ligand B (phenylphosphonic acid bis(o-isocyanophenol) ester ligand) is the same as in Example 1. Synthesis reaction formula:

[0076] The normalized UV-Vis spectral analysis results of the complex D-Ph are shown in the figure. Figure 5 Extrapolation yielded an excited-state wavelength of 386 nm.

[0077] The cyclic voltammetry results of the complex D-Ph are shown in the figure. Figure 6 .

[0078] Cyclic voltammetry of the D-Ph complex: A 0.0005 M solution of the copper complex was tested using 0.05 M Bu₄NBF₄ as the supporting electrolyte. The solution was degassed with argon for 20 minutes prior to measurement. Cyclic voltammetry scans were performed at 50 mV. -1 The scan rate was performed three times.

[0079] Based on previous literature, the triplet state energy was calculated using the value obtained by intersecting the absorption and emission spectra of copper complexes:

[0080] Data converted to saturated calomel electrode (SCE) as a control:

[0081] from Figure 5 and Figure 6 As can be seen from the data filled in the table above, E 1 / 2 (Cu I / Cu 0 The excited-state oxidation potential of the D-Ph prepared in this embodiment is +1.70 V (the reference electrode is a saturated calomel electrode), while the excited-state oxidation potential of most copper-based photocatalysts is only +1.00 V. This embodiment shows a significant improvement in the excited-state oxidation potential, which makes up for the deficiency of the weak excited-state oxidation of copper-based photocatalysts.

[0082] Example 5

[0083] {[2,9-dimethyl-1,10-phenanthroline][bis(o-isocyanophenol) phenylphosphonate]} copper tetrafluoroborate(I) complex DH (copper-based photosensitizer):

[0084] Preparation of complex DH: Compound CH (52 mg, 0.25 mmol, purchased from Accela Technology Co., Ltd., trade name: New Copper Reagent) and compound B (90.0 mg, 0.25 mmol) were added to a 100 mL three-necked flask. The mixture was then purged three times with argon gas, followed by the addition of 50 mL of dry dichloromethane. The mixture was stirred until the solid was completely dissolved, and the flask was wrapped with aluminum foil to protect it from light. Copper tetrafluoroborate tetraacetonitrile (78.5 mg, 0.25 mmol) was then added under an argon gas flow, and the mixture was stirred at approximately 25 °C for 3 hours. After the reaction was complete, the reaction solution was concentrated to the volume of a just-saturated solution, and then n-hexane (125 mL each time) was added dropwise while stirring. The product precipitated, and the solvent was removed by filtration. The filter cake was washed three times with n-hexane (total volume 30 mL). The filter cake was complex DH, with a yield of 180 mg and a yield of 100%. The synthesis method of ligand B (phenylphosphonic acid bis(o-isocyanophenol) ester ligand) is the same as in Example 1. Synthesis reaction formula:

[0085] The normalized UV-Vis spectral analysis results of the complex DH are shown in the figure. Figure 7 Extrapolation yielded an excited-state wavelength of 382 nm.

[0086] The cyclic voltammetry test results of the complex DH are shown in the figure. Figure 8 .

[0087] Cyclic voltammetry of the DH complex: A solution of the copper complex (0.0005 M) was tested using 0.05 M Bu₄NBF₄ as the supporting electrolyte. The solution was degassed with argon for 20 minutes prior to measurement. Cyclic voltammetry scans were performed at 50 mV. -1 The scan rate was performed three times.

[0088] The triplet state energy was calculated using the value obtained by intersecting the absorption and emission spectra of the copper complex:

[0089] Data converted to saturated calomel electrode (SCE) as a control:

[0090] from Figure 7and Figure 8 As can be seen from the data filled in the table above, E 1 / 2 (Cu I / Cu 0 The excited-state oxidation potential of the DH catalyst prepared in this embodiment is +1.48 V (the reference electrode is a saturated calomel electrode), while the excited-state oxidation potential of most copper-based photocatalysts is only +1.00 V. This embodiment shows a significant improvement in the excited-state oxidation potential, thus compensating for the weakness of the excited-state oxidation state of copper-based photocatalysts.

[0091] Example 6

[0092] The complex D-diCF3 provided by this invention can catalyze the oxidation of methylene quinone compounds to synthesize benzophenone compounds.

[0093]

[0094] Add 4-phenylmethylene-2,6-di-tert-butyl-2,5-cyclohexadien-1-one (58.8 mg, 0.2 mmol), (±)-N-Boc-proline (129.1 mg, 0.6 mmol), cesium carbonate (195.5 mg, 0.6 mmol), complex D-diCF3 (11.43 mg, 0.01 mmol), and N-methylpyrrolidone (4 mL) to a Schlenk reaction tube. React under air, i.e., at 38°C under 15W blue LED light for 20 hours to obtain the final reaction solution. Dilute the reaction solution with 5 mL of ethyl acetate, then wash twice with 5 mL of saturated saline solution (i.e., the total volume of saturated experimental water used is 10 mL). Remove the solvent under vacuum, and separate by column chromatography using a 50:1 (v / v) mixture of petroleum ether and ethyl acetate as the eluent (1 L of petroleum ether and 20 L of ethyl acetate). Collect the eluent containing the target product (mL), and remove the solvent by rotary evaporation to obtain 3,5-di-tert-butyl-4-hydroxybenzophenone.

[0095] In this embodiment, the complex D-diCF3 can use the carboxyl oxygen atom of a carboxylic acid compound to oxidize p-methylenequinone compounds to synthesize benzophenone compounds. Compared with other current oxidation methods [such as the method reported in the European Journal of Organic Chemistry (2022), 2022(18), e202200158], this method is green and environmentally friendly. This method is expected to replace other oxidants and solve the problem of high toxicity.

[0096]

[0097] Yellow-green solid, yield 49.0 mg, yield rate 79%.1 H NMR (400 MHz, CDCl3) δ 7.81-7.74(m, 2H), 7.72 (s, 2H), 7.60-7.53 (m, 1H), 7.47 (dd, J = 8.2, 6.7 Hz, 2H), 5.73 (s, 1H), 1.45 (s, 18H).

[0098] 13 C NMR (100 MHz, CDCl3) δ 196.37, 158.22, 138.62, 135.67, 131.74, 129.82, 128.85, 128.25, 128.11, 34.43, 30.21.

[0099] Example 7

[0100] Add p-4-(4-methylbenzyl)-2,6-di-tert-butyl-2,5-cyclohexadien-1-one (61.64 mg, 0.2 mmol), (±)-N-Boc-proline (129.1 mg, 0.6 mmol), cesium carbonate (195.5 mg, 0.6 mmol), complex D-diCF3 (11.43 mg, 0.01 mmol), and N-methylpyrrolidone (4 mL) to a Schlenk reaction tube. React under air, i.e., at 38°C under 15W blue LED light for 20 hours to obtain the final reaction solution. Use 5 mL of... Dilute the reaction solution with ethyl acetate, then wash twice with 5 mL of saturated saline solution (i.e., the total volume of saturated experimental water used is 10 mL). Remove the solvent under vacuum, and separate by column chromatography using a mixture of petroleum ether and ethyl acetate in a volume ratio of 50:1 as the eluent (where the volume of ethyl acetate is 20 mL and the volume of petroleum ether is 1 L). Collect the eluent containing the target product, and evaporate to dryness to obtain (3,5-di-tert-butyl-4-hydroxyphenyl)(p-tolyl) methyl ketone.

[0101] In this embodiment, the complex D-diCF3 can use the carboxyl oxygen atom of a carboxylic acid compound to oxidize p-methylenequinone compounds to synthesize benzophenone compounds. Compared with other current oxidation methods [such as the method reported in the European Journal of Organic Chemistry (2022), 2022(18), e202200158], this method is green and environmentally friendly. This method is expected to replace other oxidants and solve the problem of high toxicity.

[0102]

[0103] A grayish-white solid, with a yield of 22.7 mg and a yield of 35%. 1 H NMR (400 MHz, CDCl3) δ 7.72 (d, J = 9.3 Hz, 4H), 7.30 (d, J = 8.0 Hz, 2H), 5.73 (s, 1H), 2.47 (s, 3H), 1.48 (s, 18H). 13 C NMR (100 MHz, CDCl3) δ 196.15, 157.97, 142.37, 135.81, 135.56, 130.10, 129.17, 128.81, 128.10, 34.42, 30.22, 21.64.

[0104] Example 8

[0105] Add 2,6-di-tert-butyl-4-(4-ethylbenzyl)cyclohexyl-2,5-dien-1-one (67.644 mg, 0.2 mmol), (±)-N-Boc-proline (129.1 mg, 0.6 mmol), cesium carbonate (195.5 mg, 0.6 mmol), complex D-diCF3 (11.43 mg, 0.01 mmol), and N-methylpyrrolidone (4...) to a Schlenk reaction tube. The reaction was carried out under air at 38°C for 20 hours under 15W blue LED light. The reaction solution was then diluted with 5 mL of ethyl acetate and washed twice with 5 mL of saturated saline solution (i.e., the total volume of saturated experimental water used was 10 mL). The solvent was removed under vacuum, and the product was separated by column chromatography using a mixture of petroleum ether and ethyl acetate in a volume ratio of 50:1 as the eluent (20 mL of ethyl acetate and 1 L of petroleum ether). The eluent containing the target product was collected, and the solvent was removed by rotary evaporation to obtain 3,5-di-tert-butyl-4-hydroxyphenyl-p-ethylphenyl ketone.

[0106] In this embodiment, the complex D-diCF3 can use the carboxyl oxygen atom of a carboxylic acid compound to oxidize p-methylenequinone compounds to synthesize benzophenone compounds. Compared with other current oxidation methods [such as the method reported in the European Journal of Organic Chemistry (2022), 2022(18), e202200158], this method is green and environmentally friendly. This method is expected to replace other oxidants and solve the problem of high toxicity.

[0107]

[0108] Yellow liquid, yield 54.1 mg, yield 80%. 1 H NMR (400 MHz, CDCl3) δ 7.78 – 7.71(m, 4H), 7.32 (d, J = 8.0 Hz, 2H), 5.73 (s, 1H), 2.76 (q, J = 7.6 Hz, 2H),1.48 (s, 18H), 1.32 (t, J = 7.6 Hz, 3H).

[0109] 13 C NMR (100 MHz, CDCl3) δ 196.16, 157.94, 148.58, 135.98, 135.52,130.18, 129.17, 128.10, 127.61, 34.41, 30.21, 28.93, 15.24.

[0110] Example 9 Copper-based photosensitizer {[2,9-diisopropyl-4,7-(3,5-bis(trifluoromethylphenyl)-1,10-phenanthroline][bis(o-isocyanophenol) phenylphosphonate]} copper tetrafluoroborate (I) (complex P-diIPR):

[0111] Preparation method of complex P-diIPR: The synthesis method of ligand B (phenylphosphonic acid bis(o-isocyanophenol) ester ligand) is the same as in Example 1. First, McFarland acid (9.944 g, 69.0 mmol) was added to a 250 mL three-necked flask equipped with a condenser. Argon gas was purged three times, followed by the addition of trimethyl orthoformate (46 mL). The mixture was stirred and refluxed at 105 °C for 1 hour. The temperature was then lowered to 80 °C, and o-phenylenediamine (3.24 g, 30.0 mmol) was added. The mixture was stirred and refluxed at 105 °C for another hour, then cooled to room temperature and stirred for another 12 hours. After 12 hours of reaction, stirring was stopped, and the resulting mixture was filtered under reduced pressure. The filter cake was washed three times with methyl tert-butyl ether to obtain intermediate J, a white solid, with a yield of 9.362 g (75%).

[0112] Step 2: Intermediate J (4.16 g, 10.0 mmol) was added to a 250 mL three-necked flask, purged with argon gas three times, and then diphenyl ether (125.0 mL) was added. The reaction was then heated to 220 °C and stirred for 2 hours. After cooling to 70 °C, the mixture was filtered and washed successively with acetone, n-hexane, and methyl tert-butyl ether to obtain intermediate K, a brown solid with a yield of 1.91 g and a yield of 90%.

[0113]

[0114] Step 3: Add intermediate K (1.06 g, 5.0 mmol) and phosphorus oxybromide (35.75 g, 125 mmol) to a three-necked flask. Install the balloon-three-way stopcock and perform nitrogen purging three times. Stir the reaction at 105°C for 6 hours. After the reaction is complete, cool to room temperature and slowly pour the reaction solution into a mixture of 100 mL of ice and water. Continue stirring at room temperature for 1 hour. Then, add 100 mL of dichloromethane and adjust the pH to 13-14 with potassium hydroxide granules. Maintain 0°C during neutralization to prevent dichloromethane from boiling. Stir the resulting liquid using a magnetic stirrer (standard procedure for large-volume extraction). Pour the resulting liquid into a separatory funnel to separate the organic phase. Extract twice with dichloromethane (100 mL each time, total volume 200 mL). The organic phases were combined (mL), the solvent was removed under vacuum, and the mixture was separated by column chromatography using a 1:25 (v / v) mixture of methanol and dichloromethane as the eluent (50 mL of methanol and 1.25 L of dichloromethane throughout the column chromatography). The eluent containing the target product was collected, and the solvent was removed by rotary evaporation to obtain intermediate L, a light brown solid, with a yield of 0.67 g and a yield of 40%.

[0115] Step 4 (Synthesis of Compound M): Intermediate L (0.67 g, 2.0 mmol), sodium carbonate (4.24 g, 40.0 mmol), tetra(triphenylphosphine)palladium (0.23 g, 0.2 mmol), and 3,5-bis(trifluoromethyl)phenylboronic acid (2.06 g, 8.0 mmol) were added sequentially to a 250 mL three-necked flask. Argon gas was purged three times. 100 mL of 1,4-dioxane and 40 mL of deionized water were added. The mixture was stirred and refluxed at 130 °C for 48 hours. The reaction temperature was then lowered to room temperature, and the solvent was removed under vacuum. The mixture was then extracted with dichloromethane. The organic phases were combined and the solvent was removed under vacuum. Separation was performed by column chromatography using a 1:20 mixture of ethanol and dichloromethane as the eluent. During the column chromatography process, 50 mL of ethanol and 1 L of dichloromethane were used. The eluent containing the target product was collected, and the solvent was removed by rotary evaporation to obtain compound M as a white solid in a yield of 0.85 g. g, yield 70%.

[0116]

[0117] Step 5 (Synthesis of compound N-diIPR): Compound M (0.66 g, 1.0 mmol) was added to a 50 mL three-necked flask, along with a magnetic stir bar. A three-way stopcock, a protective balloon, and a rubber stopper were then installed. Argon gas was purged three times. 20 mL of anhydrous toluene was added via syringe. The apparatus was then moved to 0°C and the magnetic stirrer was turned on. Stirring was performed for 5 minutes to allow compound M to fully dissolve in the toluene, and the mixture was cooled to 0°C. 4.0 mL of a 1.0 M isopropyllithium / n-pentane solution (containing 4.0 mmol of isopropyllithium) was measured using a syringe under argon protection and added dropwise to the reaction system. Stirring was continued at 0°C for 30 minutes, then the temperature was raised to room temperature and stirred for 16 hours at room temperature. After the reaction was complete, 10.0 mL of deionized water was added to quench the reaction. The mixture was then poured into a separatory funnel to separate the organic phase. The aqueous phase was extracted three times with dichloromethane, using 20 mL of dichloromethane each time. The organic phases were combined and the solvent was removed by rotary evaporation. Dichloromethane (5.0 mL) and activated manganese dioxide (0.86 g, 10.0 mmol) were then added to the concentrated product, and the reaction was stopped after stirring at room temperature for 10 hours. The resulting mixture was filtered under reduced pressure through a diatomaceous earth layer, and the filter cake was washed three times with 50 mL of dichloromethane (total volume 150 mL). The filtrate was then evaporated by rotary evaporation to remove the solvent. The filtrate was then loaded onto a 100-200 mesh silica gel column for separation. An ethyl acetate / petroleum ether mixture with a volume ratio of 1:20 was used as the eluent (100 mL of ethyl acetate and 2.0 L of petroleum ether). The eluent containing the target product was then removed by rotary evaporation to obtain the compound N-diIPR as a yellow solid with a yield of 0.48 g and a yield of 70%.

[0118]

[0119] Step 5 (Synthesis of complex P-diIPR): Compound N-diIPR (172.04 mg, 0.25 mmol) and compound B (bis(o-isocyanophenol) ester ligand of phenylphosphonic acid) (90.0 mg, 0.25 mmol) were added to a 100 mL three-necked flask. The mixture was then purged three times with argon gas, followed by the addition of 50 mL of dry dichloromethane. The mixture was stirred until the solid was completely dissolved, and the flask was wrapped with aluminum foil to protect it from light. Copper tetrafluoroborate tetraacetonitrile (78.5 mg, 0.25 mmol) was then added under an argon gas flow, and the mixture was stirred at approximately 25 °C for 3 hours. After the reaction was complete, the reaction solution was concentrated to the volume of a just-saturated solution. This solution was then aspirated and added dropwise to n-hexane under stirring (125 mL). The product precipitated, and the solvent was removed by filtration. The filter cake was washed with n-hexane. The washed filter cake was the complex P-diIPR, with a yield of 299.54 mg, or 100%. The synthesis method of ligand B (phenylphosphonic acid bis(o-isocyanophenol) ester ligand) is the same as in Example 1.

[0120] The normalized UV-Vis spectral analysis results of the complex P-diIPR are shown in the figure. Figure 9 Extrapolation yielded an excited-state wavelength of 378 nm.

[0121] The cyclic voltammetry results of the complex P-diIPR are shown in the figure. Figure 10 .

[0122] Cyclic voltammetry of the P-diIPR complex: A solution of the copper complex (0.0005 M) was tested using 0.05 M Bu₄NBF₄ as the supporting electrolyte. The solution was degassed with argon for 20 minutes prior to measurement. Cyclic voltammetry scans were performed at 100 mV. -1 The scan rate was performed three times.

[0123] The triplet state energy was calculated using the value obtained by intersecting the absorption and emission spectra of the copper complex:

[0124] Data converted to saturated calomel electrode (SCE) as a control:

[0125] from Figure 9 and Figure 10 As can be seen from the data filled in the table above, E 1 / 2 (Cu I / Cu 0 The excited-state oxidation potential of DH prepared in this embodiment is +1.56 V (the reference electrode is a saturated calomel electrode), while the excited-state oxidation potential of most copper-based photocatalysts is only +1.00 V. This embodiment shows a significant improvement in the excited-state oxidation potential, which makes up for the deficiency of the weak excited-state oxidation of copper-based photocatalysts.

[0126] Example 10 (Synthesis method to be revised) Copper-based photosensitizer {[2,9-di-sec-butyl-4,7-(3,5-bis(trifluoromethylphenyl)-1,10-phenanthroline][bis(o-isocyanophenol) phenylphosphonate]} copper tetrafluoroborate (I) (complex P-diSBU): Copper-based photosensitizer P-diSBU:

[0127] The synthesis method of ligand B (phenylphosphonic acid bis(o-isocyanophenol) ester ligand) is the same as in Example 1.

[0128] The synthesis method of compound M is the same as that in Example 9.

[0129] First, McFarland acid (9.944 g, 69.0 mmol) was added to a 250 mL three-necked flask equipped with a condenser. Argon gas was purged three times, followed by the addition of trimethyl orthoformate (46 mL). The mixture was stirred and refluxed at 105 °C for 1 hour. The temperature was then lowered to 80 °C, and o-phenylenediamine (3.24 g, 30.0 mmol) was added. The mixture was stirred and refluxed at 105 °C for another hour, then cooled to room temperature and stirred for another 12 hours. After 12 hours of reaction, stirring was stopped, and the resulting mixture was filtered under reduced pressure. The filter cake was washed three times with methyl tert-butyl ether to obtain intermediate J, a white solid, with a yield of 9.362 g (75%).

[0130] Step 2: Intermediate J (4.16 g, 10.0 mmol) was added to a 250 mL three-necked flask, purged with argon gas three times, and then diphenyl ether (125.0 mL) was added. The reaction was then heated to 220 °C and stirred for 2 hours. After cooling to 70 °C, the mixture was filtered and washed successively with acetone, n-hexane, and methyl tert-butyl ether to obtain intermediate K, a brown solid with a yield of 1.91 g and a yield of 90%.

[0131]

[0132] Step 3: Add intermediate K (1.06 g, 5.0 mmol) and phosphorus oxybromide (35.75 g, 125 mmol) to a three-necked flask. Install the balloon-three-way stopcock and perform nitrogen purging three times. Stir the reaction at 105°C for 6 hours. After the reaction is complete, cool to room temperature and slowly pour the reaction solution into a mixture of 100 mL of ice and water. Continue stirring at room temperature for 1 hour. Then, add 100 mL of dichloromethane and adjust the pH to 13-14 with potassium hydroxide granules. Maintain 0°C during neutralization to prevent dichloromethane from boiling. Stir the resulting liquid using a magnetic stirrer (standard procedure for large-volume extraction). Pour the resulting liquid into a separatory funnel to separate the organic phase. Extract twice with dichloromethane (100 mL each time, total volume 200 mL). The organic phases were combined (mL), the solvent was removed under vacuum, and the mixture was separated by column chromatography using a 1:25 (v / v) mixture of methanol and dichloromethane as the eluent (50 mL of methanol and 1.25 L of dichloromethane throughout the column chromatography). The eluent containing the target product was collected, and the solvent was removed by rotary evaporation to obtain intermediate L, a light brown solid, with a yield of 0.67 g and a yield of 40%.

[0133] Step 4 (Synthesis of Compound M): Intermediate L (0.67 g, 2.0 mmol), sodium carbonate (4.24 g, 40.0 mmol), tetra(triphenylphosphine)palladium (0.23 g, 0.2 mmol), and 3,5-bis(trifluoromethyl)phenylboronic acid (2.06 g, 8.0 mmol) were added sequentially to a 250 mL three-necked flask. Argon gas was purged three times. 100 mL of 1,4-dioxane and 40 mL of deionized water were added. The mixture was stirred and refluxed at 130 °C for 24 hours. The reaction temperature was then lowered to room temperature, and the solvent was removed under vacuum. The mixture was then extracted with dichloromethane. The organic phases were combined and the solvent was removed under vacuum. Separation was performed by column chromatography using a 1:20 mixture of ethanol and dichloromethane as the eluent. During the column chromatography process, 50 mL of ethanol and 1 L of dichloromethane were used. The eluent containing the target product was collected, and the solvent was removed by rotary evaporation to obtain compound M as a white solid in a yield of 0.85 g. g, yield 70%.

[0134]

[0135] Step 5 (Synthesis of compound N-diSBU): Compound M (0.66 g, 1.0 mmol) was added to a 50 mL three-necked flask, along with a magnetic stir bar. A three-way stopcock, a protective balloon, and a rubber stopper were then installed. Argon gas was purged three times. 20 mL of anhydrous toluene was added via syringe. The apparatus was then moved to 0 °C and the magnetic stirrer was turned on. Stirring was performed for 5 minutes to allow compound M to fully dissolve in the toluene, and the mixture was cooled to 0 °C. 3.1 mL of a 1.3 M sec-butyllithium / cyclohexane solution (containing 4.0 mmol of sec-butyllithium) was measured using a syringe under argon protection and added dropwise to the reaction system. Stirring was continued at 0 °C for 30 minutes, then the temperature was raised to room temperature and stirred for 16 hours at room temperature. After the reaction was complete, 10.0 mL of deionized water was added to quench the reaction. The mixture was then poured into a separatory funnel to separate the organic phase. The aqueous phase was extracted three times with dichloromethane, using 20 mL of dichloromethane each time. The organic phases were combined and the solvent was removed by rotary evaporation. Dichloromethane (5.0 mL) and activated manganese dioxide (0.86 g, 10.0 mmol) were then added to the concentrated product, and the reaction was stopped after stirring at room temperature for 10 hours. The resulting mixture was filtered under reduced pressure through a diatomaceous earth layer, and the filter cake was washed three times with 50 mL of dichloromethane (total volume 150 mL). The filtrate was then evaporated by rotary evaporation to remove the solvent. The filtrate was then loaded onto a 100-200 mesh silica gel column for separation. An ethyl acetate / petroleum ether mixture with a volume ratio of 1:20 was used as the eluent (100 mL of ethyl acetate and 2.0 L of petroleum ether). The eluent containing the target product was then removed by rotary evaporation to obtain the compound N-diSBU as a yellow solid with a yield of 0.54 g and a yield of 75%.

[0136] Step 6 (Synthesis of complex P-diSBU): Compound N-diSBU (179.0 mg, 0.25 mmol) and compound B (bis(o-isocyanophenol) ester ligand of phenylphosphonic acid) (90.0 mg, 0.25 mmol) were added to a 100 mL three-necked flask. The mixture was then purged three times with argon gas, followed by the addition of 50 mL of dry dichloromethane. The mixture was stirred until the solid was completely dissolved, and the flask was wrapped with aluminum foil to protect it from light. Copper tetrafluoroborate tetraacetonitrile (78.5 mg, 0.25 mmol) was then added under an argon atmosphere, and the mixture was stirred at approximately 25 °C for 3 hours. After the reaction was complete, the reaction solution was concentrated to the volume of a just-saturated solution. This solution was then aspirated and added dropwise to n-hexane under stirring (125 mL). The product precipitated, and the solvent was removed by filtration. The filter cake was washed with n-hexane. The washed filter cake was the complex P-diSBU, with a yield of 306.55 mg, or 100%. The synthesis route is as follows:

[0137] The normalized UV-Vis spectral analysis results of the complex P-diSBU are shown in the figure. Figure 11 Extrapolation yielded an excited-state wavelength of 385 nm.

[0138] The cyclic voltammetry results of the complex P-diSBU are shown in the figure. Figure 12 .

[0139] Cyclic voltammetry of the P-diSBU complex: A solution of the copper complex (0.0005 M) was tested using 0.05 M Bu₄NBF₄ as the supporting electrolyte. The solution was degassed with argon for 20 minutes prior to measurement. Cyclic voltammetry scans were performed at 100 mV. -1 The scan rate was performed three times.

[0140] The triplet state energy was calculated using the value obtained by intersecting the absorption and emission spectra of the copper complex:

[0141] Data converted to saturated calomel electrode (SCE) as a control:

[0142] from Figure 11 and Figure 12 As can be seen from the data filled in the table above, E 1 / 2 (Cu I / Cu 0 = +1.56 V (the reference electrode is a saturated calomel electrode), while the excited-state oxidation potential of most copper-based photocatalysts is only +1.00 V. The excited-state oxidation potential of DH prepared in this embodiment is significantly improved, which makes up for the defect of weak excited-state oxidation of copper-based photocatalysts.

Claims

1. A copper-based photosensitizer as shown in Formula D, In formula D, the two Ar groups are identical and are independently selected from 3,5-bis(trifluoromethyl)phenyl, 4-tert-butylphenyl, phenyl or hydrogen atom.

2. The method for preparing the copper-based photosensitizer as described in claim 1, characterized in that, The preparation method is as follows: Under an inert gas atmosphere and in the dark, the phenylphosphonic acid bis(o-isocyanophenol) ester ligand as shown in Formula B and compound C as shown in Formula C are dissolved in dry dichloromethane. Copper tetrafluoroborate tetraacetonitrile is then added, and the mixture is stirred at 20-40°C for 2-6 hours to obtain a reaction solution. The reaction solution is added to solvent A, and the product precipitates. The liquid is removed by filtration, and the resulting filter cake is washed with solvent A to obtain the copper-based photosensitizer. Solvent A is n-hexane or diethyl ether. The molar ratio of copper tetrafluoroborate tetraacetonitrile, phenylphosphonic acid bis(o-isocyanophenol) ester ligand, and compound C is 1:1-1.2:1-1.

2. The volume of dichloromethane, based on the molar amount of copper tetrafluoroborate tetraacetonitrile, is 100-250 g. mL / mmol; the compound C is selected from 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, C-diCF3 or Cpt-Bu; 。 3. The method for preparing the copper-based photosensitizer as described in claim 2, characterized in that, The preparation method of the phenylphosphonic acid bis(o-isocyanophenol) ester ligand as shown in Formula B is as follows: Under an inert gas atmosphere, compound A (as shown in Formula A) is mixed with anhydrous tetrahydrofuran, cooled to -95 to -65°C, and a solution of n-butyllithium dissolved in an organic solvent is added. After stirring at -95 to -65°C for 0.5 to 4 hours, diphenylphosphine chloride is added, and the mixture is stirred at room temperature for another 8 to 10 hours. The resulting reaction solution is post-treated to obtain phenylphosphonic acid bis(o-isocyanophenol) ester ligand as shown in Formula B. The molar ratio of compound A, n-butyllithium, and diphenylphosphine chloride is 1:0.55-1.25:0.20-0.

75. 。 4. The method for preparing the copper-based photosensitizer as described in claim 3, characterized in that, The volume of the anhydrous tetrahydrofuran is 1-7.5 based on the amount of substance of compound A.

5. The method for preparing the copper-based photosensitizer as described in claim 3, characterized in that, The post-treatment is as follows: a mixed solution of saturated sodium bicarbonate solution and methyl tert-butyl ether at a volume ratio of 1:2-3 at 0°C is added to the reaction solution for quenching and extraction. The organic phase is taken, dried with anhydrous sodium sulfate, and concentrated by rotary evaporation. The obtained sample is separated by a 100-200 mesh silica gel column to obtain a crude product. The crude product is dissolved in hot acetonitrile solution for recrystallization to obtain the phenylphosphonic acid bis(o-isocyanophenol) ester ligand.

6. The method for preparing the copper-based photosensitizer as described in claim 2, characterized in that, The preparation method of C-diCF3 is as follows: (1) Under an argon atmosphere, mix McFarland acid and trimethyl orthoacetate, stir and reflux at 50-120°C for 0.25-3 hours, lower the temperature to 50-90°C, add o-phenylenediamine, stir and reflux at 50-120°C for 0.25-3 hours, lower the temperature to room temperature, and continue stirring for 6-18 hours. After the reaction is complete, filter the resulting mixture and wash the filter cake with methyl tert-butyl ether to obtain intermediate G as shown in formula G; the molar ratio of McFarland acid to o-phenylenediamine is 2.0-4.0:1, and the volume of trimethyl orthoacetate is 1-3 mL / mmol based on the molar amount of o-phenylenediamine; (2) Under an argon atmosphere, the intermediate G described in step (1) is mixed with diphenyl ether and stirred at 180-255°C for 0.25-4 hours. After cooling to 45-90°C, the mixture is filtered. The resulting filter cake is washed sequentially with acetone, n-hexane, and methyl tert-butyl ether to obtain intermediate H as shown in formula H. The volume of the diphenyl ether is 5-20 mL / mmol based on the amount of intermediate G. (3) Under an argon atmosphere, intermediate H and phosphorus oxybromide described in step (2) are mixed and stirred at 75-130°C for 2-8 hours. After the reaction is completed, the mixture is cooled to room temperature. The resulting reaction solution is added to an ice-water mixture and stirred for 0.5-3 hours. Then dichloromethane is added and potassium hydroxide is added to adjust the pH to 13-14. The organic phases are separated and combined. The solvent is removed under vacuum and separated by column chromatography. A mixture of methanol and dichloromethane is used as the eluent. The eluent containing the target product is collected and evaporated to dryness to obtain intermediate I as shown in Formula I. The molar ratio of intermediate H to phosphorus oxybromide is 1:5-30. (4) Under an argon atmosphere, the intermediate I, the basic substance, the palladium catalyst and 3,5-bis(trifluoromethyl)phenylboronic acid described in step (3) are dissolved in a mixed solvent of 1,4-dioxane and deionized water. After stirring and refluxing at 70-140°C for 12-48 minutes, the reaction temperature is lowered to room temperature. The solvent is removed by vacuum distillation under vacuum conditions, and then dichloromethane is added for extraction. The organic phases are combined and collected. The solvent is removed under vacuum conditions. The mixture is separated by column chromatography. A mixed solvent of ethanol and ethyl acetate is used as the eluent. The eluent containing the target product is collected and evaporated to dryness to obtain compound C-diCF3. The molar ratio of the intermediate I, 3,5-bis(trifluoromethyl)phenylboronic acid, palladium catalyst and basic substance is 1:2-6:0.05-0.3:5-30. The volume of the mixed solvent of 1,4-dioxane and deionized water is 50 mL / mmol based on the amount of intermediate I. 。 7. The method for preparing the copper-based photosensitizer as described in claim 2, characterized in that, The preparation method of Cpt-Bu is as follows: Under an argon atmosphere, intermediate I, 4-tert-butylphenylboronic acid, a basic substance, a palladium catalyst, a phosphine ligand, 1,4-dioxane, and deionized water were added sequentially. After stirring and refluxing at 60-130°C for 2-12 seconds, the reaction temperature was lowered to room temperature. The solvent was removed under vacuum, followed by extraction with dichloromethane. The organic phases were combined and collected. The solvent was removed under vacuum, and the mixture was separated by column chromatography using a mixed solvent of ethanol and ethyl acetate as the eluent. The eluent containing the target product was collected and evaporated to dryness to obtain compound Cpt-Bu. The molar ratio of intermediate I, 4-tert-butylphenylboronic acid, the basic substance, the palladium catalyst, and the phosphine ligand was 1:2-8:2-9:0.02-0.2:0.03-0.

3.

8. An intermediate for the preparation of copper-based photosensitizers, such as the phenylphosphonic acid bis(o-isocyanophenol) ester ligand of Formula B: 。 9. The application of the copper-based photosensitizer as described in claim 1 in the catalytic oxidation reaction of methylenequinone compounds.

10. The application as described in claim 1, characterized in that, The process described is as follows: under alkaline conditions, organic solvents, and visible light irradiation, the copper-based photosensitizer is used as a catalyst to catalyze the oxidation reaction of methylene quinone compounds and proline derivatives to generate benzophenone compounds.

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