Thiophene-modified copper-cluster metal covalent organic framework material and application thereof in photocatalysis of organic conversion of thioamide into thiadiazole

Abstract

The invention relates to a thiophene-modified copper-cluster metal covalent organic framework material and application of the thiophene-modified copper-cluster metal covalent organic framework material in photocatalysis of organic conversion of thioamide into thiadiazole. According to the invention, a cyclic trinuclear copper cluster unit is used as a raw material, and the cyclic trinuclear copper cluster unit, 2, 5-bis (thiophene-2-yl) benzene-1, 4-diamine (alpha SPA) and 2, 5-bis (thiophene-3-yl) benzene-1, 4-diamine (beta SPA) are prepared into two types of thiophene modified copper cluster metal covalent organic framework (M-COF) materials with efficient charge separation efficiency through a solvothermal method. The material is applied to the field of photocatalytic organic conversion, and thioamide cyclization and conversion of derivatives of thioamide are achieved under irradiation of a white light LED. The prepared M-COF has excellent charge separation efficiency and electron mobility, the catalyst is applied to performance research of photocatalytic thioamide cyclization reaction, and the synthesis strategy of the catalyst has wide substrate universality and functional group compatibility. The activity is not obviously attenuated after continuous and repeated recycling, and the efficient and sustainable photocatalytic conversion performance is manifested.

Description

Technical Field

[0001] This invention pertains to the preparation of metal covalent organic framework materials and their application in the field of photocatalytic organic conversion. Specifically, it relates to a method for preparing a thiophene-modified copper cluster metal covalent organic framework material. Background Technology

[0002] The overconsumption of traditional fossil fuels has led to increasing resource depletion and serious environmental problems. Developing green technologies that can control pollution has become an urgent need for achieving sustainable development. Photocatalysis technology can convert solar energy into chemical energy, showing great potential in alleviating the energy crisis and environmental pollution. Among these technologies, visible light-driven organic synthesis, with its advantages of mild conditions, low energy consumption, and environmental friendliness, provides a new pathway for the green synthesis of high-value-added chemicals.

[0003] However, photocatalysis technology still faces challenges such as high recombination rates of photogenerated carriers and limited visible light utilization efficiency, which restrict its practical application. Existing catalysts, such as semiconductor materials, covalent organic frameworks (COFs), and metal-organic frameworks (MOFs), generally suffer from insufficient stability and unclear active sites.

[0004] In recent years, researchers have proposed constructing metal covalent organic frameworks (MCOFs) by anchoring metal species within COFs to combine the ordered structure of COFs with the catalytic function of metal sites, thereby achieving efficient photogenerated charge separation and controllable photocatalytic activity. Although MCOFs have shown great promise in catalysis and energy storage, their practical applications are still limited by insufficient photochemical stability and energy level mismatch between the metal and ligands. To address these issues, this study designed a thiophene-modified copper cluster-based MCOF material, aiming to improve its stability and catalytic performance through structural regulation, thereby promoting the development of photocatalytic synthesis technology. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of low charge separation efficiency and high stability of traditional MCOFs, and to provide a thiophene-modified copper cluster metal covalent organic framework material, denoted as Cu3- α SPA-MCOF and Cu3- β SPA-MCOF. Two metal-covalent organic frameworks were then used in the study of thioamide cyclization reactions.

[0006] Preparation of Cu3- α SPA-MCOF and Cu3- β The SPA-MCOF method includes the following steps: (a) Synthesis of Cu3L, a cyclic trinuclear copper cluster unit Copper salt and pyrazole ligand were dissolved in a mixed solvent of organic and water. The homogenized solution was then transferred to a high-pressure reactor and heated at a specific temperature. After the reaction, needle-like crystals were obtained. Finally, under vacuum, a cyclic trinuclear copper cluster unit structure (denoted as Cu3L) was obtained. (b) Monomer 2,5-bis(thiophene-2-yl)phenyl-1,4-diamine α Synthesis of SPA 2,5-Dibromo-1,4-phenylenediamine and its derivatives, 2-thienylboronic acid and its derivatives, and palladium salts were dissolved in degassed organic solvents and alkaline solutions, and stirred under an argon atmosphere. After cooling to room temperature, the solvent was removed by vacuum distillation, and the residue was purified by column chromatography to obtain a solid powder. (c) Monomer 2,5-bis(thiophen-3-yl)phenyl-1,4-diamine ( β Synthesis of SPA 2,5-Dibromo-1,4-phenylenediamine and its derivatives, 3-thienylboronic acid and its derivatives, and palladium salts were dissolved in degassed organic solvents and alkaline solutions, and stirred under an argon atmosphere. After cooling to room temperature, the solvent was removed by vacuum distillation, and the residue was purified by column chromatography to obtain a solid powder. (d) Synthesis of thiophene-modified copper cluster M-COF materials The prepared Cu3L reacted with 2,5-bis(thiophene-2-yl)phenyl-1,4-diamine ( α SPA) and 2,5-bis(thiophene-3-yl)phenyl-1,4-diamine ( β SPA) was mixed in a certain proportion, and a certain volume ratio of n-butanol and o-dichlorobenzene was added. Then, a certain amount of strong acid was added as a catalyst, and the reaction was carried out under heat in a closed environment to obtain two types of thiophene-modified copper cluster M-COF materials, denoted as Cu3- α SPA-MCOF and Cu3- β SPA-MCOF.

[0007] The copper salt of Cu3L mentioned in step (a) is copper acetate, copper sulfate, copper nitrate, copper chloride, copper trifluoromethanesulfonate, basic copper carbonate, etc., with copper nitrate being preferred; The heating temperature is set to the specified reaction temperature of 80-120℃ and maintained for 12-24 hours. The preferred reaction temperature is 100℃ and the reaction time is 12 hours.

[0008] The solvents are DMF, H2O, and EtOH; In steps (b) and (c), the volume ratio of solvent THF to H2O is 1-4:1-4, preferably 3:1; The palladium salts are palladium chloride, palladium nitrate, palladium sulfate, palladium acetate, tetraphenylphosphine palladium, palladium on carbon, etc., with tetraphenylphosphine palladium being preferred; The alkali is a hydroxide of alkali metals and some alkaline earth metals, such as sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, sodium bicarbonate, and potassium bicarbonate; potassium carbonate is preferred.

[0009] The addition of Cu3L and 2,5-bis(thiophene-2-yl)phenyl-1,4-diamine in step (d) α The molar ratio of SPA is 1-4:1-4, preferably 2:3, and the solvent volume ratio of o-dichlorobenzene to n-butanol is 1-10:1-10, preferably 7:3; The concentration of trifluoroacetic acid added in step (d) includes 3 M, 6 M, and 12 M, with 6 M being preferred; Cu3- α The reaction temperature of SPA-MCOF is heated to 120-180 ℃ and maintained for 3-7 days, with the preferred reaction temperature being 120 ℃ and the reaction time being 3 days; The addition of Cu3L and 2,5-bis(thiophen-3-yl)phenyl-1,4-diamine in step (d) β The molar ratio of SPA is 1-4:1-4, preferably 2:3, and the solvent volume ratio of o-dichlorobenzene to n-butanol is 1-10:1-10, preferably 7:3; The concentration of trifluoroacetic acid added in step (d) includes 3 M, 6 M, and 12 M, with 6 M being preferred.

[0010] Cu3- β The reaction temperature of SPA-MCOF is heated to 120-180℃ and maintained for 3-7 days, with the preferred reaction temperature being 120℃ and the reaction time being 3 days.

[0011] A procedure for synthesizing 1,2,4-thiadiazole using M-COF: A certain amount of thioamide derivative and M-COF photocatalyst are weighed, and a certain volume of reaction solvent is measured and placed in a light-transmitting glass bottle. The solvent is fully dissolved to ensure uniform dispersion. Next, a certain volume of gas is introduced to maintain the stability of the reaction system. The glass bottle is placed under a light source, and the suspension is continuously stirred to promote the reaction. The mixture is irradiated at a certain temperature for a certain time to carry out the catalytic reaction; the specific time depends on the experimental design. After the experiment, the reaction system is processed, the product is collected and analyzed to confirm the success of the reaction and the catalytic effect of the photocatalyst. The reaction formula is as follows:

[0012] The oxidant mentioned is a highly reactive oxygen species that can be generated during organic transformation reactions and intervene in the aerobic organic reaction process. The R is any one of H, alkyl, alkoxy, aromatic or halogen; The amount of catalyst used is 1-20% of the substrate feed mass, preferably 18%; The solvent is any one of acetone, acetonitrile, dichloromethane, methanol, and ethanol, with acetonitrile being preferred. The gas introduced is air or oxygen; The light source is ultraviolet LED, blue LED, white LED, orange LED, and green LED, with white LED being preferred; The reaction temperature is at room temperature and the light exposure time is 3-24 h, preferably 18 h.

[0013] The structural stability of the thiophene-modified copper cluster M-COF photocatalyst described in this invention after repeated use in photocatalytic reactions: In the aforementioned catalytic reaction process, a recycling experiment of the M-COF photocatalyst was conducted. M-COF can be rapidly recovered from the reaction system by centrifugation, washed with solution, and then used in the next cycle without additional treatment or activation. The photocatalytic experimental steps were repeated to achieve… N The loop continues.

[0014] The solvent used for washing according to step 5 is methanol, ethanol, acetonitrile, ethyl acetate, or dichloromethane, with ethanol being preferred.

[0015] According to the cyclic experiment described in step 5, it is necessary to achieve N The next loop. N Greater than or equal to 3.

[0016] The specific beneficial effects of this material are manifested as follows: (1) This invention introduces thiophene isomers into the side chains of MCOFs, wherein β (3-) Substitution of the thiophene unit results in lower steric hindrance and improved framework planarity, leading to the substitution of sulfur at the ortho-carbon position (thiophene). α The active sites of the carbon atoms are fully exposed, thereby enhancing their hole accumulation capacity and substrate oxidation activity; (2) The thiophene-modified copper cluster MCOF structure synthesized in this invention contains donor-acceptor type structural units. Wherein β The modification of the thiophene unit side chain by substituting the thiophene unit enhances the charge transfer between the donor and acceptor. The transfer of photogenerated electrons from the thiophene unit to the copper cluster unit realizes the spatial separation of electron-hole pairs, effectively suppresses electron-hole pair recombination, and improves the lifetime of photogenerated carriers. This exhibits superior charge separation efficiency and photocatalytic performance. (3) It maintains high catalytic activity and low catalyst loss in multiple cycles and has good stability (no less than 3 cycles of catalysis in Example 5, and the activity retention rate does not decrease significantly after the cycle). (4) In this invention, white light is used as the light source and thiophene-modified copper cluster MCOF is used as a photocatalyst to cyclize thioamides and their derivatives into 1,2,4-thiadiazoles and their derivatives. The yield of the product 1,2,4-thiadiazoles and their derivatives can reach up to 78% (Example 3), showing excellent photocatalytic activity. Attached Figure Description

[0017] Figure 1 The image shows the X-ray powder diffraction pattern of Cu3L material.

[0018] Figure 2 The 1H NMR spectrum of 2,5-bis(thiophene-2-yl)phenyl-1,4-diamine.

[0019] Figure 3 The 1H NMR spectrum of 2,5-bis(thiophene-3-yl)phenyl-1,4-diamine.

[0020] Figure 4 Cu3L and Cu3- α Synthesis route diagram of SPA-MCOF material.

[0021] Figure 5 Cu3L and Cu3- β Synthesis route diagram of SPA-MCOF material.

[0022] Figure 6 Cu3- α SPA-MCOF and Cu3- β X-ray powder diffraction pattern of SPA-MCOF material.

[0023] Figure 7 Cu3L and Cu3- α Fourier transform infrared spectrum of SPA-MCOF material.

[0024] Figure 8 Cu3L and Cu3- β Fourier transform infrared spectrum of SPA-MCOF material.

[0025] Figure 9 The 1H NMR spectrum of 3,5-diphenyl-1,2,4-thiadiazole.

[0026] Figure 10 The 1H NMR spectrum of 4,4'-(1,2,4-thiadiazole-3,5-diyl)diphenylamine.

[0027] Figure 11 The 1H NMR spectrum of 3,5-bis(4-methoxyphenyl)-1,2,4-thiadiazole.

[0028] Figure 12 The 1H NMR spectrum of 3,5-bis(4-bromophenyl)-1,2,4-thiadiazole.

[0029] Figure 13 The 1H NMR spectrum of 3,5-bis(4-(trifluoromethyl)phenyl)-1,2,4-thiadiazole.

[0030] Figure 14 The NMR spectrum of 3,5-bis(3-chlorophenyl)-1,2,4-thiadiazole is shown in the 1H NMR spectrum.

[0031] Figure 15 The NMR spectrum of 3,5-bis(3-bromophenyl)-1,2,4-thiadiazole is shown in the 1H NMR spectrum.

[0032] Figure 16 The image shows the 1H NMR spectrum of 3,5-di-o-tolyl-1,2,4-thiadiazole.

[0033] Figure 17 Cu3- β XRD patterns before and after SPA-MCOF cycling. Detailed Implementation

[0034] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0035] Example 1 Synthesis of Cu3L: Cu(NO3)2·3H2O (0.83 mmol, 0.20 g) and 1H-pyrazole-4-carboxaldehyde (1.0 mmol, 0.096 g) were dissolved in a mixed solvent of DMF (6.7 mL), H2O (5 mL), and ethanol (6.7 mL). The homogeneous solution was then transferred to a high-pressure reactor and heated at 100°C for 12 h. After the reaction, the resulting pale yellow needle-like crystals were soaked in deionized water for three days, with the deionized water changed six times daily. Finally, the crystals were dried under vacuum at 120°C for 24 h, and this was denoted as Cu3L.

[0036] Figure 1 The image shows the X-ray powder diffraction pattern of Cu3L. The simulated X-ray powder diffraction pattern of Cu3L was compared with that of synthesized Cu3L. The results showed that the diffraction peaks largely overlapped and no other impurity peaks were observed, indicating that the Cu3L prepared by this method is a pure substance.

[0037] Example 1-1 Synthesis of 2,5-bis(thiophen-2-yl)phenyl-1,4-diamine: 2,5-Dibromo-1,4-phenylenediamine (50.0 mg, 0.19 mmol), 2-thienylboronic acid (72.5 mg, 0.60 mmol), and Pd(PPh3)4 (21.6 mg, 0.019 mmol) were dissolved in a certain amount of degassed THF and potassium carbonate solution (1 M, 1 mL), and stirred at 80 °C for 24 h under an argon atmosphere. After cooling to room temperature, the black solution was diluted with ethyl acetate (30 mL) and H2O, and the organic phase was dried over anhydrous Na2SO4. The solvent was removed by vacuum distillation, and the residue was purified by column chromatography to give a greenish-brown solid in 55% yield.

[0038] Figure 2 The 1H NMR spectrum of 2,5-bis(thiophene-2-yl)phenyl-1,4-diamine. 1 H NMR (600 MHz, Chloroform- d ): δ 7.35-7.34 (dd, J = 5.1, 1.1 Hz, 1H), 7.25-7.24 (dd, J = 3.6, 1.2Hz, 1H), 7.13-7.11 (dd, J = 5.1, 3.5 Hz, 1H), 6.81 (s, 1H), 3.70 (s, 2H). Examples 1-2 Synthesis of 2,5-bis(thiophene-3-yl)phenyl-1,4-diamine: 2,5-Dibromo-1,4-phenylenediamine (50.0 mg, 0.19 mmol), 3-thienylboronic acid (72.5 mg, 0.60 mmol), and Pd(PPh3)4 (21.6 mg, 0.019 mmol) were dissolved in a certain amount of degassed THF and potassium carbonate solution (1 M, 1 mL), and stirred at 80 °C for 24 h under an argon atmosphere. After cooling to room temperature, the black solution was diluted with ethyl acetate (30 mL) and H2O, and the organic phase was dried over anhydrous Na2SO4. The solvent was removed by vacuum distillation, and the residue was purified by column chromatography to give a greenish-brown solid in 79% yield.

[0039] Figure 3 The 1H NMR spectrum of 2,5-bis(thiophene-3-yl)phenyl-1,4-diamine. 1 H NMR (400 MHz, Chloroform- d ): δ 7.43-7.40 (m, 2H), 7.29-7.28 (dd, J= 4.7, 1.5 Hz, 1H), 6.73(s, 1H), 3.28 (s, 2H). Example 2 Weigh out Cu3L (23.7 mg, 0.05 mmol) and 2,5-bis(thiophene-2-yl)phenyl-1,4-diamine (20.5 mg, 0.075 mmol) and disperse them in ampoules containing o-dichlorobenzene and n-butanol (0.7 mL / 0.3 mL, v / v). Then add trifluoroacetic acid (6 M, 0.1 mL), and flame-seal the ampoule under a sealed environment. Heat to 120°C for 3 days. After the reaction is complete, wash with methanol, ethanol, dichloromethane, and DMF, filter, and dry under vacuum at 80°C overnight to obtain black Cu3- α SPA-MCOF powder sample.

[0040] Figure 4 Cu3L and Cu3- α Synthesis route diagram of SPA-MCOF material.

[0041] Example 2-1 Weigh out Cu3L (23.7 mg, 0.05 mmol) and 2,5-bis(thiophene-3-yl)phenyl-1,4-diamine (20.5 mg, 0.075 mmol) and disperse them in ampoules containing o-dichlorobenzene and n-butanol (0.7 mL / 0.3 mL, v / v). Then add trifluoroacetic acid (6 M, 0.1 mL), and flame-seal the ampoule under a sealed environment. Heat to 120°C for 3 days. After the reaction is complete, wash with methanol, ethanol, dichloromethane, and DMF, filter, and dry under vacuum overnight at 80°C to obtain black Cu3- β SPA-MCOF powder sample.

[0042] Figure 5 Cu3L and Cu3- β Synthesis route diagram of SPA-MCOF material.

[0043] Figure 6 for α Position and β X-ray powder diffraction pattern of thiophene-modified copper cluster M-COF material. The copper cluster M-COF material contains... α X-ray powder diffraction of thiophene-modified copper cluster M-COF materials showed strong 2- spectral density at approximately 3.04°, 5.20°, 8.24°, and 25.53°. θ Angular signal peak; βX-ray powder diffraction of the thiophene-modified copper cluster M-COF material showed strong 2- spectral density at approximately 3.11°, 5.36°, and 25.94°. θ Angular signal peak; Figure 7 Cu3L and Cu3- α Fourier transform infrared spectrum of SPA-MCOF material. In the copper cluster M-COF material: α The infrared spectrum of the thiophene-modified copper cluster M-COF material at 1620 cm⁻¹ -1 The presence of characteristic absorption peaks of C=N bonds nearby confirmed the formation of imine bonds, thus demonstrating the successful construction of the MCOF material.

[0044] Figure 8 Cu3L and Cu3- β Fourier transform infrared spectrum of SPA-MCOF material. In the copper cluster M-COF material: β The infrared spectrum of the thiophene-modified copper cluster M-COF material at 1620 cm⁻¹ -1 The presence of characteristic absorption peaks of C=N bonds nearby confirmed the formation of imine bonds, thus demonstrating the successful construction of the MCOF material.

[0045] Example 3 Synthesis of 3,5-diphenyl-1,2,4-thiadiazole:

[0046] Weigh out 0.2 mmol of thioamide and 5 mg of Cu3- β The SPA-MCOF photocatalyst was placed in a 12 mL transparent glass reactor, and 2 mL of MeCN was added. A certain amount of O2 was introduced, and the glass bottle was placed in a white light reactor. The mixture was stirred at room temperature for 18 h to obtain 3,5-diphenyl-1,2,4-thiadiazole (18.6 mg, 78%, separation yield).

[0047] Figure 9 The image shows the 1H NMR spectrum of 3,5-diphenyl-1,2,4-thiadiazole. 1 H NMR (400 MHz, Chloroform- d ): δ 8.41-8.39 (m, 2H), 8.07-8.05 (d, J = 7.9 Hz, 2H), 7.54-7.50 (m, 6H).; The figure shows that 3,5-diphenyl-1,2,4-thiadiazole was successfully synthesized.

[0048] Example 3-1 Synthesis of 4,4'-(1,2,4-thiadiazole-3,5-diyl)diphenylamine:

[0049] Weigh 0.2 mmol of 4-aminothiocarboxamide and 5 mg of Cu3- β The SPA-MCOF photocatalyst was placed in a 12 mL transparent glass reaction flask. 2 mL of MeCN was added as solvent, and oxygen was continuously bubbled into the system for 2 min. Subsequently, the reaction flask was placed in a photochemical reactor with a white LED light source, and the reaction was continuously stirred at room temperature for 18 h. After the reaction, the solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain 4,4'-(1,2,4-thiadiazole-3,5-diyl)diphenylamine (14.0 mg, 52%, isolated yield).

[0050] Figure 10 The image shows the 1H NMR spectrum of 4,4'-(1,2,4-thiadiazole-3,5-diyl)diphenylamine. 1 H NMR (400 MHz, Chloroform- d ) δ 7.43-7.41 (d, J = 8.2 Hz, 4H), 6.6-6.63 (d, J = 8.7 Hz, 4H), 4.14-4.08 (s, 4H); As can be seen from the figure, we have successfully synthesized 4,4'-(1,2,4-thiadiazole-3,5-diyl)diphenylamine.

[0051] Example 3-2 Synthesis of 3,5-bis(4-methoxyphenyl)-1,2,4-thiadiazole:

[0052] 0.2 mmol of 4-methoxythioformamide was mixed with 5 mg of Cu3- β The SPA-MCOF photocatalyst was added to a light-transmitting glass reaction tube. Then, 2 mL of MeCN solvent was added, and the reaction tube was sealed and purged with O2. The reaction system was placed in a white light reaction apparatus and stirred at room temperature for 18 h. After the reaction was complete, the solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain high-purity 3,5-bis(4-methoxyphenyl)-1,2,4-thiadiazole (20.3 mg, 68%, separation yield).

[0053] Figure 11 The 1H NMR spectrum of 3,5-bis(4-methoxyphenyl)-1,2,4-thiadiazole is shown.1 H NMR (400 MHz, Chloroform- d ): δ 8.33-8.31 (s, 2H), 8.00-7.98 (s, 2H), 7.02-6.99 (s, 4H), 3.89-3.88 (s, 6H); The figure shows that 3,5-bis(4-methoxyphenyl)-1,2,4-thiadiazole was successfully synthesized.

[0054] Example 3-3 Synthesis of 3,5-bis(4-bromophenyl)-1,2,4-thiadiazole:

[0055] In a glass reaction flask, add 0.2 mmol of 4-bromothioformamide and 5 mg of Cu3- sequentially. β The reaction flask was prepared using SPA-MCOF photocatalyst and 2 mL of acetonitrile solvent. The flask was connected to an oxygen bulb, and the atmosphere was purged three times to ensure the reaction proceeded under an O2 atmosphere. The flask was then placed in a white light reactor and stirred at room temperature for 18 h. After the reaction was complete, the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography to give 3,5-bis(4-bromophenyl)-1,2,4-thiadiazole (21.4 mg, 54%, isolated yield).

[0056] Figure 12 The image shows the 1H NMR spectrum of 3,5-bis(4-bromophenyl)-1,2,4-thiadiazole. 1 H NMR (400 MHz, Chloroform- d ): δ 8.26-8.24 (s, 2H), 7.92-7.90 (s, 2H), 7.68-7.63 (s, 4H); As can be seen from the figure, we have successfully synthesized 3,5-bis(4-bromophenyl)-1,2,4-thiadiazole.

[0057] Example 4 Synthesis of 3,5-bis(4-(trifluoromethyl)phenyl)-1,2,4-thiadiazole:

[0058] Weigh out 0.2 mmol of 4-trifluoromethylformamide and 5 mg of Cu3- αThe SPA-MCOF photocatalyst was placed in a 12 mL transparent glass reactor, and 2 mL of MeCN was added. A certain amount of O2 was introduced, and the glass bottle was placed in a white light reactor. The mixture was stirred at room temperature for 18 h to obtain 3,5-bis(4-(trifluoromethyl)phenyl)-1,2,4-thiadiazole (18.7 mg, 50%, separation yield).

[0059] Figure 13 The image shows the 1H NMR spectrum of 3,5-bis(4-(trifluoromethyl)phenyl)-1,2,4-thiadiazole. 1 H NMR (400MHz, Chloroform- d ): δ 8.53-8.51 (d, J = 8.1 Hz, 2H), 8.19-8.17 (d, J = 8.1 Hz, 2H), 7.82-7.77 (dd, J = 13.6, 8.2 Hz, 4H); As can be seen from the figure, we have successfully synthesized 3,5-bis(4-(trifluoromethyl)phenyl)-1,2,4-thiadiazole.

[0060] Example 4-1 Synthesis of 3,5-bis(3-chlorophenyl)-1,2,4-thiadiazole:

[0061] Weigh 0.2 mmol of 3-chlorophenylthiocarboxamide and 5 mg of Cu3- α The SPA-MCOF photocatalyst was placed in a 12 mL transparent glass reaction flask. 2 mL of acetonitrile was added as a solvent, and oxygen was continuously bubbled into the system for 2 min. Subsequently, the reaction flask was placed in a photochemical reactor with a white LED light source, and the reaction was continuously stirred at room temperature for 18 h. After the reaction was complete, the solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain 3,5-bis(3-chlorophenyl)-1,2,4-thiadiazole (16.9 mg, 55%, isolated yield).

[0062] Figure 14 The 1H NMR spectrum of 3,5-bis(3-chlorophenyl)-1,2,4-thiadiazole 1 H NMR (400 MHz, Chloroform- d ) δ 8.38 (d, J = 2.0 Hz, 1H), 8.27 (d, J = 6.9 Hz, 1H), 8.08 (t, J=1.8 Hz, 1H), 7.90 (dt, J = 7.6, 1.5 Hz, 1H), 7.58 - 7.39 (m, 5H).; As can be seen from the figure, we have successfully synthesized 3,5-bis(3-chlorophenyl)-1,2,4-thiadiazole.

[0063] Example 4-2 Synthesis of 3,5-bis(3-bromophenyl)-1,2,4-thiadiazole:

[0064] 0.2 mmol of 3-bromophenylthiocarboxamide was mixed with 5 mg of Cu3- α The SPA-MCOF photocatalyst was added to a light-transmitting glass reaction tube. Then, 2 mL of MeCN solvent was added, and the reaction tube was sealed and purged with O2. The reaction system was placed in a white light reaction apparatus and stirred at room temperature for 18 h. After the reaction was complete, the solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain a high-purity product, 3,5-bis(3-bromophenyl)-1,2,4-thiadiazole (19.0 mg, 48%, separation yield).

[0065] Figure 15 The image shows the 1H NMR spectrum of 3,5-bis(3-bromophenyl)-1,2,4-thiadiazole. 1 ¹H NMR (400 MHz, Chloroform-d) δ 8.55 (t, J = 1.8 Hz, 1H), 8.31 (dt, J = 7.8, 1.3 Hz, 1H), 8.23 ​​(t, J = 1.8 Hz, 1H), 7.94 (dt, J = 7.8, 1.3 Hz, 1H), 7.77 - 7.57 (m, 3H), 7.39 (dt, J = 10.7, 7.9 Hz, 2H). The graph shows that we successfully synthesized 3,5-bis(3-chlorophenyl)-1,2,4-thiadiazole.

[0066] Example 4-3 Synthesis of 3,5-di-o-tolyl-1,2,4-thiadiazole:

[0067] In a glass reaction flask, add 0.2 mmol of 2-methylthioformamide and 5 mg of Cu3- in sequence. αSPA-MCOF photocatalyst and 2 mL MeCN were used. The reaction flask was connected to an oxygen bulb, and the atmosphere was purged three times to ensure the reaction proceeded under an O2 atmosphere. The reaction flask was then placed in a white light reactor and stirred at room temperature for 18 h. After the reaction was complete, the solvent was removed by vacuum distillation. The crude product was purified by silica gel column chromatography to give 3,5-di-o-tolyl-1,2,4-thiadiazole (15.5 mg, 58%, isolated yield).

[0068] Figure 16 The 1H NMR spectrum of 3,5-di-o-tolyl-1,2,4-thiadiazole. 1 H NMR (600 MHz, Chloroform- d ): δ 8.16-8.15 (d, J = 7.6 Hz, 1H), 8.06-8.05 (dd, J = 7.6, 1.4 Hz,1H), 7.45-7.42 (td, J = 7.4, 1.4 Hz, 1H), 7.39-7.31 (m, 5H), 2.73-2.70 (d, J =20.0 Hz, 6H). As can be seen from the figure, we have successfully synthesized 3,5-di-o-tolyl-1,2,4-thiadiazole.

[0069] Example 5 Cyclic stability test: Cu3- β SPA-MCOF was used as a photocatalyst for the photocatalytic organic conversion of thioamides and their derivatives in Example 3, producing 1,2,4-thiadiazoles and their derivatives. After the reaction was complete, the catalyst could be separated from the reaction system by a simple filtration operation, and after washing and drying with dichloromethane, it could be used directly for subsequent reactions without activation. Systematic cyclic stability assessment showed that the catalyst maintained high activity in at least three consecutive repeated experiments.

[0070] Figure 17 For metal covalent organic framework Cu3- β PXRD patterns before and after SPA-MCOF cycling; experimental results show that after three cycles, the above-mentioned reaction still maintains high photocatalytic activity. Furthermore, the Cu3- recovered after three cycles... β The PXRD of SPA-MCOF remained essentially unchanged, indicating that Cu3- β SPA-MCOF photocatalysts exhibit good stability.

[0071] In summary, this method provides a thiophene-modified copper cluster metal covalent organic framework photocatalyst and its application in photocatalytic organic conversion. The prepared Cu3- α SPA-MCOF and Cu3- β SPA-MCOF was applied to the organic conversion of thioamides and their derivatives, catalyzing the production of 1,2,4-thiadiazoles and their derivatives with a separation efficiency of up to 78%. This catalyst exhibited highly efficient photocatalytic performance and good stability.

[0072] The above description is merely a preferred embodiment of the present invention, but the invention is not limited to the disclosed content. Therefore, any modifications or equivalents made without departing from the scope of the present invention fall within the protection scope of the present invention.

Claims

1. A thiophene-modified copper cluster M-COF material, characterized in that, The structure is as follows: ； In this structural formula, the side chain contains a five-membered heterocyclic structure, where X=S and Y=H, then it is... α Thiophene-modified copper cluster M-COF material; X=H, Y=S, then it is β M-COF material with copper clusters modified with thiophene.

2. The thiophene-modified copper cluster M-COF material according to claim 1, characterized in that, α X-ray powder diffraction of thiophene-modified copper cluster M-COF materials showed strong 2- spectral density at approximately 3.04°, 5.20°, 8.24°, and 25.53°. θ Angular signal peak; β X-ray powder diffraction of the thiophene-modified copper cluster M-COF material showed strong 2- spectral density at approximately 3.11°, 5.36°, and 25.94°. θ Angular signal peak; α Thiophene-modified copper cluster M-COF materials or β The infrared spectrum of the thiophene-modified copper cluster M-COF material at 1620 cm⁻¹ -1 The presence of characteristic absorption peaks of C=N bonds nearby confirmed the formation of imine bonds, thus demonstrating the successful construction of the MCOF material.

3. The method for preparing thiophene-modified copper cluster M-COF material according to claim 1, characterized in that, Includes the following steps: (a) Synthesis of Cu3L, a cyclic trinuclear copper cluster unit Copper salt and pyrazole ligand were dissolved in an organic solution and subjected to a solvothermal reaction to obtain a cyclic trinuclear copper cluster unit product, denoted as Cu3L. (b) Monomer 2,5-bis(thiophen-2-yl)phenyl-1,4-diamine α SPA synthesis 2,5-Dibromo-1,4-phenylenediamine or its derivatives, 2-thienylboronic acid or its derivatives, and palladium salts were dissolved in a degassed organic solvent and an alkaline solution. After stirring under an inert atmosphere, the solvent was removed by vacuum distillation. The resulting solid powder was purified by column chromatography. α SPA; (c) Monomer 2,5-bis(thiophen-3-yl)phenyl-1,4-diamine β SPA synthesis 2,5-Dibromo-1,4-phenylenediamine or its derivatives, 3-thienylboronic acid or its derivatives, and palladium salts were dissolved in a degassed organic solvent and an alkaline solution. After stirring under an inert atmosphere, the solvent was removed by vacuum distillation. The resulting solid powder was purified by column chromatography. β SPA; (d) Synthesis of thiophene-modified copper cluster M-COF materials The prepared Cu3L was respectively with α SPA or β SPA was mixed, and then a certain amount of n-butanol and o-dichlorobenzene were added respectively. A certain amount of strong acid was then added as a catalyst, followed by a thermal reaction in a closed environment to obtain two types of thiophene-modified copper cluster M-COF materials, denoted as Cu3- α SPA-MCOF and Cu3- β SPA-MCOF.

4. The preparation method according to claim 3, characterized in that, The copper salt mentioned in step (a) includes any one of copper acetate, copper sulfate, copper nitrate, copper chloride, copper trifluoromethanesulfonate, or basic copper carbonate; The solvothermal reaction temperature is 80-120℃, and the reaction time is 12-24 h; or the solvothermal reaction temperature is 100℃, and the reaction time is 12 h.

5. The preparation method according to claim 3, characterized in that, In step (b) or (c), the volume ratio of solvent THF to H2O is 1-4:1-4, or 3:1; Palladium salts include any one of palladium chloride, palladium nitrate, palladium sulfate, palladium acetate, tetraphenylphosphine palladium, or palladium on carbon; The derivatives of 2,5-dibromo-1,4-phenylenediamine or its derivatives include any one of 4-amino-2,6-dibromoaniline, 2,5-dibromo-1,3-phenylenediamine, and 3,6-dibromo-1,2-phenylenediamine; 2-Thienylboronic acid or its derivatives include any one of 4-methyl-2-thienylboronic acid, 5-methylthiophen-2-boronic acid, 3-methylthien-2-boronic acid, and 5-ethylthien-2-boronic acid; 3-Thienylboronic acid or its derivatives include any one of 5-methylthien-3-boronic acid, 2,5-dimethylthien-3-boronic acid, and 5-ethylthien-3-ylboronic acid.

6. The preparation method according to claim 3, characterized in that, In step (d), Cu3L is respectively with α SPA or β The SPA molar ratio is 1-4:1-4, or 2:3; The solvent volume ratio of o-dichlorobenzene to n-butanol is 1-10:1-10, or 7:3; The acid mentioned is any one of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, trifluoromethanesulfonic acid, trifluoroacetic acid, benzoic acid, or p-toluenesulfonic acid; The concentration of the acid ranges from 3 M to 12 M, or is 6 M; The thermal reaction temperature is 100-180℃ and maintained for 3-5 days; or the reaction temperature is 120℃ and the reaction time is 3 days.

7. A photocatalyst for the photocatalytic conversion of thioamides to thiadiazoles, characterized in that, The catalyst is the thiophene-modified copper cluster M-COF material according to claim 1 or 2, or the thiophene-modified copper cluster M-COF material prepared by the preparation method according to any one of claims 3-6.

8. The method for generating thiodiazole by photocatalysis of thioamide using the photocatalyst described in claim 7, characterized in that, Includes the following steps: At a certain temperature, thioamides or thioamide derivatives are added to an organic solvent, followed by the addition of thiophene-modified copper cluster M-COF material. Under light irradiation and with the atmosphere introduced, the reaction proceeds for a period of time to obtain thiadiazole. The reaction formula is as follows: The R is any one of H, alkyl, alkoxy, and halogen, and the substitution position of the functional group includes any one of ortho, meta, or para.

9. The method according to claim 8, characterized in that, The alkyl group is C1-C 10 The alkoxy group is a straight-chain alkane or a branched-chain alkane; the alkoxy group includes one of methoxy, ethoxy or propoxy, and the halogen is any one of F, Cl, Br or I; The organic solvent includes any one of acetone, acetonitrile, DMF, THF, dichloromethane, methanol, and ethanol.

10. The method according to claim 8, characterized in that, The amount of thiophene-modified copper cluster M-COF material used is 1-20% of the mass of thioamide or thioamide derivative.

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