Preparation method and application of benzothiadiazole-based Zr-MOF material

Abstract

The application discloses a preparation method of a benzothiadiazole Zr-MOF material, and specifically comprises the following steps: firstly, a product 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid is prepared; the obtained product is reacted with NaOH and a THF / MeOH / H2O mixed solvent to obtain a product organic ligand SP; and a zirconium salt, the organic ligand SP and an organic acid are added into an organic solvent to perform a self-assembly reaction, so as to obtain the benzothiadiazole Zr-MOF material. The application fully utilizes the porosity, large specific surface area and excellent stability of the Zr-MOF material, and promotes the Zr-MOF material to be used as a heterogeneous photocatalyst to efficiently and repeatedly catalyze condensation and cyclization of o-phenylenediamine and benzaldehyde derivatives to prepare 2-phenylbenzimidazole derivatives.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic material preparation technology, specifically relating to a method for preparing benzothiadiazole-based Zr-MOF materials, and also to the application of such benzothiadiazole-based Zr-MOF materials. Background Technology

[0002] Benzimidazole is an important pharmaceutical intermediate, widely found in natural drug compounds, and possesses antibacterial, anticancer, antiviral, anti-inflammatory, antidiabetic, and antioxidant properties. Condensation cyclization reactions using o-phenylenediamine and benzaldehyde compounds are common methods for constructing the benzimazole skeleton. To date, a series of catalytic systems have been developed for this synthesis, but these methods typically require extreme conditions such as acidity or high temperatures. Photocatalysis, however, offers a greener, milder, more efficient, and functionally-tolerant synthetic approach.

[0003] Metal-organic frameworks (MOFs), as a new class of porous materials, possess advantages such as large specific surface area, high porosity, and strong designability, and are widely used in photocatalysis. Among these, organic ligands, due to their flexible structural design characteristics, have become one of the important pathways for MOF material modification. Using benzothiadiazole, which has high chemical stability, ease of modification, and strong electron affinity, as the parent material, a donor-acceptor-donor (DAD) type organic ligand was designed and synthesized, and functionalized Zr-MOF materials were constructed, showing great application potential. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing benzothiadiazole-based Zr-MOF materials, which solves the problems of low catalytic activity and low recycling rate of existing Zr-MOF materials.

[0005] Another object of the present invention is to provide the application of the above-mentioned benzothiadiazole-based Zr-MOF material in the catalytic condensation cyclization reaction of o-phenylenediamine and benzaldehyde derivatives.

[0006] The technical solution adopted in this invention is a method for preparing benzothiadiazole-based Zr-MOF materials, which is specifically implemented according to the following steps:

[0007] Step 1: Prepare product 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid;

[0008] Step 2: React the product obtained in Step 1 with a mixed solvent of NaOH, THF / MeOH / H2O to obtain the organic ligand SP.

[0009] Step 3: Zirconium salt, organic ligand SP, and organic acid are added to an organic solvent to carry out a self-assembly reaction, thereby obtaining benzothiadiazole-based Zr-MOF material.

[0010] The invention is further characterized in that,

[0011] Step 1 specifically involves:

[0012] Dimethyl 4,4'-(5,6-diaminobenzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoate was mixed with p-aldehyde benzoic acid, and then trifluoroacetic acid and DMSO were added. The mixture was heated and stirred under N2 protection. After the reaction was completed, deionized water was added, and a light red solid precipitated. The solid was filtered, dried, and washed with methanol to remove excess impurities, yielding the product 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazole-6-yl)benzoic acid.

[0013] The molar ratio of 4,4'-(5,6-diaminobenzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoate, p-aldehyde benzoic acid, trifluoroacetic acid, and DMSO is 1:1:17:85; the stirring reaction temperature is 80-100℃, and the reaction time is 6-8h.

[0014] Step 2 specifically involves:

[0015] 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid was mixed with NaOH, and a mixed solvent of THF / MeOH / H2O was added. Under N2 protection, the mixture was heated and stirred. After the reaction was completed, the THF and MeOH in the solvent were rotary evaporated, and deionized water was added. Hydrochloric acid solution was added dropwise until the pH of the solution was 1, and the mixture was stirred at room temperature for 2 hours. A solid precipitated in the solution. The product was filtered to obtain a red product and washed with distilled water until neutral to obtain the organic ligand SP.

[0016] The molar ratio of 8-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid, NaOH, THF, MeOH and H2O was 1:18:124:615:278; the stirring reaction temperature was 80-90℃, and the reaction time was 6-8h.

[0017] Step 3 specifically involves:

[0018] Zirconium salt, organic ligand SP, and organic acid were added to an organic solvent and ultrasonically dispersed. The mixture was then heated and stirred to carry out a self-assembly reaction. The resulting product was separated using a high-speed centrifuge and washed 2-3 times with DMF. The solid was obtained by centrifugation and then washed 2-3 times with methanol. The solid was obtained by centrifugation and vacuum drying to obtain a light yellow powder SP-Zr, which is the benzothiadiazole-based Zr-MOF material.

[0019] The ultrasonic dispersion time was 20-30 min; the zirconium salt was ZrCl4; the organic acid was benzoic acid; the organic solvent was N,N-dimethylformamide; and the molar ratio of zirconium salt, organic ligand SP, organic acid, and organic solvent was 3:1:52:5.

[0020] The self-assembly reaction temperature is 100-120℃, and the self-assembly time is 48-72h; the vacuum drying temperature is 60-80℃, and the vacuum drying time is 6-12h.

[0021] Another technical solution adopted in this invention is the application of benzothiadiazole-based Zr-MOF materials in the catalytic synthesis of 2-phenylbenzimidazole derivatives from o-phenylenediamine and benzaldehyde derivatives.

[0022] The beneficial effects of this invention are: by using benzothiadiazole, which has high chemical stability, is easy to modify, and has strong electron affinity, as a parent material, a donor-acceptor-donor (DAD) type organic ligand was designed and synthesized, and a functionalized benzothiadiazole-based Zr-MOF material was constructed; by fully utilizing the porosity, large specific surface area, and excellent stability of Zr-MOF material, it is promoted to act as a heterogeneous photocatalyst for the efficient and repetitive catalysis of the condensation cyclization of o-phenylenediamine and benzaldehyde derivatives to prepare 2-phenylbenzimidazole derivatives. Attached Figure Description

[0023] Figure 1 This is a flowchart of the preparation method of the organic ligand SP in the benzothiadiazole-based Zr-MOF material of the present invention;

[0024] Figure 2 This is a flowchart of the preparation method of the benzothiadiazole-based Zr-MOF material of the present invention;

[0025] Figure 3 The XRD powder spectra of SP-Zr synthesized by the method of this invention and the simulated UiO-68 are shown.

[0026] Figure 4 The Fourier transform infrared spectra of the organic ligands SP, SP-Zr, and SP-Zr after being immersed in FeCl3 solution are shown in the present invention.

[0027] Figure 5 This is the thermogravimetric spectrum of SP-Zr synthesized by the method of this invention;

[0028] Figure 6 This is the XRD powder pattern of SP-Zr of the present invention after being soaked in various organic solvents for one week;

[0029] Figure 7 These are the solid-state fluorescence emission spectra of the invented organic ligands SP and SP-Zr;

[0030] Figure 8 These are the XRD powder spectra of SP-Zr after photocatalysis and MOF before photocatalysis. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0032] The preparation method of the benzothiadiazole-based Zr-MOF material of the present invention is specifically implemented according to the following steps:

[0033] Step 1: Dimethyl 4,4'-(5,6-diaminobenzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoate was mixed with p-aldehyde benzoic acid, and then trifluoroacetic acid and DMSO were added. Under N2 protection, the mixture was heated and stirred. After the reaction was completed, deionized water was added, and a light red solid precipitated. The solid was filtered, dried, and washed with methanol to remove excess impurities, yielding the product 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazole-6-yl)benzoic acid.

[0034] The molar ratio of 4,4'-(5,6-diaminobenzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoate, p-aldehyde benzoic acid, trifluoroacetic acid, and DMSO is 1:1:17:85.

[0035] The stirring reaction temperature is 80-100℃, and the reaction time is 6-8 hours;

[0036] Step 2: Mix 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid and NaOH, add a mixed solvent of THF / MeOH / H2O, and carry out the reaction under N2 protection by heating and stirring. After the reaction is completed, evaporate the THF and MeOH in the solvent by rotary evaporation, add deionized water, add hydrochloric acid solution dropwise until the pH of the solution is 1, and stir at room temperature for 2 hours. A solid precipitates in the solution. Filter to obtain a red product and wash with distilled water until neutral to obtain the product organic ligand SP.

[0037] The molar ratio of 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid, NaOH, THF, MeOH and H2O is 1:18:124:615:278;

[0038] The stirring reaction temperature is 80-90℃, and the reaction time is 6-8 hours;

[0039] Step 3: Zirconium salt, organic ligand SP, and organic acid are added to an organic solvent and ultrasonically dispersed. The mixed solution is then heated and stirred to carry out a self-assembly reaction. The product is separated by a high-speed centrifuge and washed 2-3 times with DMF. The solid is obtained by centrifugation and then washed 2-3 times with methanol. The solid is obtained by centrifugation and vacuum drying to obtain a light yellow powder SP-Zr, which is the benzothiadiazole-based Zr-MOF material.

[0040] The ultrasonic dispersion time was 20-30 min; the zirconium salt was ZrCl4; the organic acid was benzoic acid; and the organic solvent was N,N-dimethylformamide.

[0041] The molar ratio of zirconium salt, organic ligand SP, organic acid, and organic solvent is 3:1:52:5;

[0042] The self-assembly reaction temperature is 100-120℃, and the self-assembly time is 48-72h.

[0043] The vacuum drying temperature is 60-80℃, and the vacuum drying time is 6-12 hours.

[0044] The benzothiadiazole-based Zr-MOF material (SP-Zr) prepared by the method of this invention is used as a heterogeneous photocatalyst to efficiently catalyze the condensation cyclization of o-phenylenediamine and benzaldehyde derivatives to prepare 2-phenylbenzimidazole derivatives. Specifically:

[0045] o-Phenylenediamine (0.12 mmol), benzaldehyde derivatives (0.1 mmol), and SP-Zr (5 mg) were dissolved in acetonitrile (2 mL). An LED lamp was used as the light source, and the reaction was carried out at 20-30°C for 4 hours. After the reaction, the mixture was centrifuged at high speed, and the supernatant was collected. The supernatant was then evaporated to dryness using a rotary evaporator. The collected solid was subjected to column chromatography (silica gel: 200-300 mesh; developing solvent: petroleum ether, ethyl acetate) to obtain benzimidazole products. Further column chromatography yielded 2-phenylbenzimidazole derivatives. The illumination conditions were a 10W 450nm LED lamp; the volume ratio of petroleum ether to ethyl acetate was 4:1. This catalyst shortened the reaction time and achieved a separation yield of up to 98%. Furthermore, the catalyst can be recovered and reused five times with a yield still up to 80%.

[0046] Example 1

[0047] The method for preparing benzothiadiazole-based Zr-MOF materials of the present invention, as follows: Figure 1 As shown, please follow these steps:

[0048] Step 1: Dimethyl 4,4'-(5,6-diaminobenzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoate was mixed with p-aldehyde benzoic acid, and then trifluoroacetic acid and DMSO were added. Under N2 protection, the mixture was heated and stirred. After the reaction was completed, deionized water was added, and a light red solid precipitated. The solid was filtered, dried, and washed with methanol to remove excess impurities, yielding the product 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazole-6-yl)benzoic acid.

[0049] The molar ratio of 4,4'-(5,6-diaminobenzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoate, p-aldehyde benzoic acid, trifluoroacetic acid, and DMSO is 1:1:17:85.

[0050] The stirring reaction temperature was 100℃, and the reaction time was 8 hours.

[0051] The product data are as follows:

[0052] 1 H NMR (400MHz, CF3OOD) δ: 8.44 (d, J = 8.1 Hz, 6H), 8.27 (d, J = 7.9 Hz, 2H), 8.00 (d, J = 7.8 Hz, 4H), 4.18 (s, 6H). 13 C NMR (101MHz, CF3OOD) δ: 170.3, 169.9, 157.2, 151.5, 136.2, 135.3, 132.1, 131.6, 131.1, 130.9, 130.6, 129.5, 125.3, 118.2, 53.1. HRMS(ESI)m / z:[MH] - calcd for C 30 H 20 N4O6S: 563.1082; found: 563.1075.

[0053] Step 2: Mix 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid and NaOH, add a mixed solvent of THF / MeOH / H2O, and heat and stir under N2 protection. After the reaction is complete, evaporate the THF and MeOH in the solvent by rotary evaporation, add deionized water, add hydrochloric acid solution dropwise until the pH of the solution is 1, and stir at room temperature for 2 hours. A solid precipitates in the solution. Filter to obtain a red product and wash with distilled water until neutral to obtain the organic ligand SP. Figure 1 The diagram shown is a schematic diagram of the synthesis of the benzothiadiazole-based Zr-MOF organic ligand SP.

[0054] The molar ratio of 5-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid, NaOH, THF, MeOH and H2O is 1:18:124:615:278;

[0055] The stirring reaction temperature was 85℃, and the reaction time was 6 hours.

[0056] The product data are as follows:

[0057] 1 H NMR (400MHz, DMSO-d6) δ: 13.11 (s, 3H), 12.97 (s, 1H), 8.46–8.35 (m, 4H), 8.14 (d, J = 7.7Hz, 5H), 8.07–8.03 (m, 3H). 13 C NMR (101MHz, DMSO-d6) δ: 167.3, 166.7, 158.4, 150.5, 138.8, 132.9, 132.3, 131.2, 130.9, 129.9, 129.4, 129.1, 128.4. HRMS(ESI)m / z:[M+H] + calcd for C 28 H 16 N4O6S: 537.0863; found: 537.0826.

[0058] Step 3: Zirconium salt, organic ligand SP and organic acid are added to organic solvent and ultrasonically dispersed. Then the mixed solution is heated and stirred to carry out self-assembly reaction. The product is separated by high-speed centrifuge and washed twice with DMF. The solid is obtained by centrifugation and then washed twice with methanol. The solid is obtained by centrifugation and vacuum drying to obtain a light yellow powder SP-Zr, which is benzothiadiazole-based Zr-MOF material.

[0059] The ultrasonic dispersion time was 20 min; the zirconium salt was ZrCl4; the organic acid was benzoic acid; and the organic solvent was N,N-dimethylformamide.

[0060] The molar ratio of zirconium salt, organic ligand SP, organic acid, and organic solvent is 3:1:52:5;

[0061] The self-assembly reaction temperature was 120℃, and the self-assembly time was 72h.

[0062] The vacuum drying temperature is 60℃, and the vacuum drying time is 10 hours.

[0063] Example 2

[0064] The method for preparing benzothiadiazole-based Zr-MOF materials of the present invention, as follows: Figure 2 As shown, please follow these steps:

[0065] Step 1: Dimethyl 4,4'-(5,6-diaminobenzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoate was mixed with p-aldehyde benzoic acid, and then trifluoroacetic acid and DMSO were added. Under N2 protection, the mixture was heated and stirred. After the reaction was completed, deionized water was added, and a light red solid precipitated. The solid was filtered, dried, and washed with methanol to remove excess impurities, yielding the product 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazole-6-yl)benzoic acid.

[0066] The molar ratio of 4,4'-(5,6-diaminobenzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoate, p-aldehyde benzoic acid, trifluoroacetic acid, and DMSO is 1:1:17:85.

[0067] The stirring reaction temperature was 100℃, and the reaction time was 8 hours.

[0068] Step 2: Mix 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid and NaOH, add a mixed solvent of THF / MeOH / H2O, and carry out the reaction under N2 protection by heating and stirring. After the reaction is completed, evaporate the THF and MeOH in the solvent by rotary evaporation, add deionized water, add hydrochloric acid solution dropwise until the pH of the solution is 1, and stir at room temperature for 2 hours. A solid precipitates in the solution. Filter to obtain a red product and wash with distilled water until neutral to obtain the product organic ligand SP.

[0069] The molar ratio of 6-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid, NaOH, THF, MeOH and H2O is 1:18:124:615:278;

[0070] The stirring reaction temperature was 85℃, and the reaction time was 6 hours.

[0071] Step 3: Zirconium salt, organic ligand SP, and organic acid are added to an organic solvent and ultrasonically dispersed. The mixed solution is then heated and stirred to carry out a self-assembly reaction. The product is separated by a high-speed centrifuge and washed 2-3 times with DMF. The solid is obtained by centrifugation and then washed 2-3 times with methanol. The solid is obtained by centrifugation and vacuum drying to obtain a light yellow powder SP-Zr, which is the benzothiadiazole-based Zr-MOF material.

[0072] The ultrasonic dispersion time was 20 min; the zirconium salt was ZrCl4; the organic acid was benzoic acid; and the organic solvent was N,N-dimethylformamide.

[0073] The molar ratio of zirconium salt, organic ligand SP, organic acid, and organic solvent is 3:1:52:5;

[0074] The self-assembly reaction was carried out at a temperature of 120°C for 48 hours.

[0075] The vacuum drying temperature is 70℃, and the vacuum drying time is 6 hours.

[0076] Example 3

[0077] The method for preparing benzothiadiazole-based Zr-MOF materials of the present invention, as follows: Figure 1 As shown, please follow these steps:

[0078] Step 1: Dimethyl 4,4'-(5,6-diaminobenzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoate was mixed with p-aldehyde benzoic acid, and then trifluoroacetic acid and DMSO were added. Under N2 protection, the mixture was heated and stirred. After the reaction was completed, deionized water was added, and a light red solid precipitated. The solid was filtered, dried, and washed with methanol to remove excess impurities, yielding the product 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazole-6-yl)benzoic acid.

[0079] The molar ratio of 4,4'-(5,6-diaminobenzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoate, p-aldehyde benzoic acid, trifluoroacetic acid, and DMSO is 1:1:17:85.

[0080] The stirring reaction temperature was 100℃, and the reaction time was 8 hours.

[0081] Step 2: Mix 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid and NaOH, add a mixed solvent of THF / MeOH / H2O, and carry out the reaction under N2 protection by heating and stirring. After the reaction is completed, evaporate the THF and MeOH in the solvent by rotary evaporation, add deionized water, add hydrochloric acid solution dropwise until the pH of the solution is 1, and stir at room temperature for 2 hours. A solid precipitates in the solution. Filter to obtain a red product and wash with distilled water until neutral to obtain the product organic ligand SP.

[0082] The molar ratio of 7-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid, NaOH, THF, MeOH and H2O is 1:18:124:615:278;

[0083] The stirring reaction temperature was 85℃, and the reaction time was 6 hours.

[0084] Step 3: Zirconium salt, organic ligand SP, and organic acid are added to an organic solvent and ultrasonically dispersed. The mixed solution is then heated and stirred to carry out a self-assembly reaction. The product is separated by a high-speed centrifuge and washed 2-3 times with DMF. The solid is obtained by centrifugation and then washed 2-3 times with methanol. The solid is obtained by centrifugation and vacuum drying to obtain a light yellow powder SP-Zr, which is the benzothiadiazole-based Zr-MOF material.

[0085] The ultrasonic dispersion time was 20 min; the zirconium salt was ZrCl4; the organic acid was benzoic acid; and the organic solvent was N,N-dimethylformamide.

[0086] The molar ratio of zirconium salt, organic ligand SP, organic acid, and organic solvent is 3:1:52:5;

[0087] The self-assembly reaction was carried out at a temperature of 120°C for 48 hours.

[0088] The vacuum drying temperature is 80℃, and the vacuum drying time is 12h.

[0089] Figure 3 The XRD powder spectrum of SP-Zr prepared by the method of this invention and the simulated spectrum of UiO-68 type MOF are shown in the figure. It can be seen from the figure that SP-Zr and UiO-68 type have the same structure.

[0090] Figure 4These are the infrared spectra of organic ligands SP, SP-Zr, and SP-Zr soaked in FeCl3. Infrared spectroscopy tests show that SP-Zr has a wavelength of 1700 cm⁻¹. -1 A strong peak is present, which can be attributed to the asymmetric stretching vibration of the carbonyl group on the free carboxyl group in the framework, indicating the presence of an uncoordinated carboxyl group in the framework. After immersing SP-Zr in FeCl3 solution, the asymmetric stretching vibration of the corresponding carbonyl group shifts to a lower wavenumber, further confirming the presence of uncoordinated carboxyl groups in the SP-Zr structure.

[0091] Figure 5 This is the thermogravimetric spectrum of SP-Zr. The thermogravimetric spectrum shows that SP-Zr has good thermal stability, and the framework only begins to collapse when the temperature is raised to 475℃. Figure 6 The XRD patterns of SP-Zr after standing in different solvents for one week show that SP-Zr can remain stable in different solvents for at least 7 days. Figure 7 These are the solid-state fluorescence emission spectra of SP and SP-Zr. It can be seen that SP and SP-Zr have a wide visible light absorption range, which is conducive to the photocatalytic reaction.

[0092] Figure 8 The figures show the photocatalytic SP-Zr, the MOF before catalysis, and simulated UiO-68 XRD powder spectra. As can be seen from the figures, the MOF framework structure remained unchanged after five consecutive catalytic cycles, demonstrating excellent reusability. The high photocatalytic efficiency of this catalyst is attributed to two main factors: the benzothiadiazole ligands selected for the MOF have a wide visible light absorption range; and the pores and channels of the MOF enhance the transport rate of substrate, solvent, and product molecules into and out of the pores, thus improving catalytic efficiency.

Claims

1. A method for preparing benzothiadiazole-based Zr-MOF materials, characterized in that, The specific steps are as follows: Step 1, preparing the product 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid; specifically: Dimethyl 4,4'-(5,6-diaminobenzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoate was mixed with p-aldehyde benzoic acid, and then trifluoroacetic acid and DMSO were added. The mixture was heated and stirred under N2 protection. After the reaction was complete, deionized water was added, and a pale red solid precipitated. The solid was filtered, dried, and washed with methanol to remove excess impurities, yielding the product 4-(4,8-bis(4-(methoxycarbonyl)). The reaction mixture consisted of phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazole-6-yl)benzoic acid; 4,4'-(5,6-diaminobenzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoate, p-aldehyde benzoic acid, trifluoroacetic acid, and DMSO in a molar ratio of 1:1:17:85; the reaction temperature was 80-100℃, and the reaction time was 6-8h. Step 2 involves reacting the product obtained in Step 1 with a mixed solvent of NaOH, THF / MeOH / H2O to obtain the organic ligand SP; specifically: 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid was mixed with NaOH, and a mixed solvent of THF / MeOH / H2O was added. Under N2 protection, the mixture was heated and stirred. After the reaction was completed, the THF and MeOH in the solvent were evaporated by rotary evaporation, and deionized water was added. Hydrochloric acid solution was added dropwise until the pH of the solution was 1 and stirred at room temperature for 2 hours. A solid precipitated in the solution. The product was filtered to obtain a red product and washed with distilled water until neutral to obtain the organic ligand SP. Step 3: Zirconium salt, organic ligand SP and organic acid are added to an organic solvent to carry out a self-assembly reaction to obtain benzothiadiazole-based Zr-MOF material.

2. The method for preparing benzothiadiazole-based Zr-MOF material according to claim 1, characterized in that, The molar ratio of 4-(4,8-bis(4-(methoxycarbonyl)phenyl)-5H-imidazo[4',5':4,5]benzo[1,2-c][1,2,5]thiadiazol-6-yl)benzoic acid, NaOH, THF, MeOH and H2O was 1:18:124:615:278; the stirring reaction temperature was 80-90℃, and the reaction time was 6-8h.

3. The method for preparing benzothiadiazole-based Zr-MOF material according to claim 1, characterized in that, Step 3 specifically involves: Zirconium salt, organic ligand SP, and organic acid were added to an organic solvent and ultrasonically dispersed. The mixture was then heated and stirred to carry out a self-assembly reaction. The resulting product was separated using a high-speed centrifuge and washed 2-3 times with DMF. The solid was obtained by centrifugation and then washed 2-3 times with methanol. The solid was obtained by centrifugation and vacuum drying to obtain a pale yellow powder SP-Zr, which is the benzothiadiazole-based Zr-MOF material.

4. The method for preparing benzothiadiazole-based Zr-MOF material according to claim 3, characterized in that, The ultrasonic dispersion time was 20-30 min; the zirconium salt was ZrCl4; the organic acid was benzoic acid; the organic solvent was N,N-dimethylformamide; and the molar ratio of zirconium salt, organic ligand SP, organic acid, and organic solvent was 3:1:52:

5.

5. The method for preparing benzothiadiazole-based Zr-MOF material according to claim 3, characterized in that, The self-assembly reaction temperature is 100-120℃, and the self-assembly time is 48-72h; the vacuum drying temperature is 60-80℃, and the vacuum drying time is 6-12h.

6. The application of the benzothiadiazole-based Zr-MOF material prepared by any one of claims 1-5 in the catalytic synthesis of 2-phenylbenzimidazole derivatives from o-phenylenediamine and benzaldehyde derivatives.

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