Hexabenzocoronene-based metal organic framework capable of directed modification, preparation method therefor and use thereof
By introducing different substituents and large conjugated structures into Zr-based metal-organic frameworks, the problems of narrow absorption regions and easy photodegradation of existing materials in the field of photocatalysis have been solved, improving the chemical stability and photocatalytic performance of MOFs and expanding their application potential.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- NANKAI UNIV
- Filing Date
- 2025-03-09
- Publication Date
- 2026-05-21
AI Technical Summary
Existing semiconductor materials suffer from problems such as narrow absorption regions, easy photodegradation, and low quantum yield in the field of photocatalysis. Furthermore, it is difficult to simultaneously introduce different substituents and large conjugated structures into metal-organic frameworks, which limits their practical applications.
A series of Zr-based metal-organic frameworks with different substituents and large conjugated structures were synthesized by employing a symmetry-based ligand reduction strategy. Substituents and large conjugated structures were introduced into long-range ordered frameworks by combining pre-modification and post-synthetic cyclization.
This study improved the chemical stability and photocatalytic effect of MOF materials, broadened the band gap, and increased the generation and migration efficiency of photogenerated electrons, resulting in excellent photocatalytic performance.
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Figure CN2025081479_21052026_PF_FP_ABST
Abstract
Description
A directionally modifiable hexabenzoxyl metal-organic framework, its preparation method and application Technical Field
[0001] This invention relates to the synthesis of metal-organic frameworks and photocatalysis, specifically to a directionally modifiable hexabenzoxyl metal-organic framework, its preparation method, and its applications. Background Technology
[0002] Energy shortages and climate change are the most severe and pressing challenges facing the 21st century. Rapid industrialization has led to excessive carbon dioxide emissions. One of the most direct and effective ways to alleviate this problem is to utilize solar energy to convert excess carbon dioxide into substances beneficial to humankind. In the past few decades, many semiconductor materials, such as TiO2, CdS, and C3N4, have been used as photocatalysts, but they suffer from drawbacks such as narrow absorption regions, easy photodegradation, and low quantum yields, which greatly hinder their further practical applications.
[0003] The directed synthesis and selection of organic ligands and metal ions have rapidly made metal-organic frameworks (MOFs) popular materials in the field of photocatalysis, with broad practical application prospects. Currently, most research focuses on improving the separation efficiency of photogenerated carriers and suppressing carrier recombination. Conversely, there is a lack of breakthrough reports on the precise control / regulation of carrier generation sources. Some simple methods for regulating photogenerated carrier sources have yielded some results, such as introducing amino substituents and other functional groups that affect conjugation effects and enhance visible light absorption. These improvements have made MOFs such as NH2-UiO-66, NH2-MIL-125, and PCN-222 star materials in photocatalysis research. Furthermore, there are also numerous reports in the literature on extending the conjugated structure itself. In 2019, Professor Zhou Hongcai and others reported a strategy for constructing hexaphenylkeratyl MOFs using post-synthetic modification. The successful implementation of this strategy transformed the non-absorbent pbz-MOF-1 into the highly absorbent PCN-136, achieving the successful construction of a large conjugated structure in MOF materials. However, due to the high symmetry of the HCHC ligand in PCN-136, as well as limitations imposed by topological structure and synthetic thermodynamics, simultaneously introducing different substituents and a large conjugated structure into MOFs is a significant challenge, and no relevant literature has reported on this to date. Summary of the Invention
[0004] To address the existing technical problems in this field, this invention synthesizes a series of Zr-based metal-organic frameworks with different substituents and large conjugated structures based on a symmetry reduction strategy of ligands. The Zr-based metal-organic frameworks involved in this invention have the advantages of excellent chemical and water stability, excellent photocatalytic effect, and simple synthesis method.
[0005] To solve the above problems, the technical solution adopted by the present invention is as follows:
[0006] The first aspect of this invention aims to provide a method for preparing directionally modifiable hexabenzoxyl Zr-MOFs, which involves adding H3BTB, H4BDQDA-R ligand, ZrCl4, and benzoic acid to N,N-dimethylformamide (DMF), stirring thoroughly to dissolve the reactants, and obtaining crystalline Zr-MOFs after the reaction; collecting the obtained crystalline product by centrifugation, and washing it with fresh DMF and acetone to obtain columnar Zr-MOFs with the same topological network;
[0007] In H4BDQDA-R, R = -NO2, -H, - t Bu, -OCH3, -OH and -NH2 have the following structures:
[0008] Furthermore, H4BDQDA-H is obtained through the following method:
[0009] Dibenzyl ketone was reacted with 1,2-bis(4-bromophenyl)ethane-1,2-dione under alkaline conditions to generate compound 2 with a five-membered ring central structure. Compound 2 was then reacted with di(4-bromophenyl)yne under high temperature conditions with diphenyl ether as solvent to generate compound 3 with a six-membered ring (benzene ring) central structure. Compound 3 then underwent a Suzuki coupling reaction with ethyl phenylboronic acid to generate compound 4. Finally, compound 4 was hydrolyzed under alkaline conditions to obtain the H4BDQDA-H ligand.
[0010] Furthermore, H4BDQDA- t Bu is obtained through the following method:
[0011] p-tert-butylphenylacetic acid was dissolved in anhydrous dichloromethane and reacted with a dichloromethane solution containing DCC and DMAP to give compound 5. Compound 5 was reacted with 1,2-bis(4-bromophenyl)ethane-1,2-dione under alkaline conditions to generate compound 6 with a five-membered ring central structure. Compound 6 was reacted with di(4-bromophenyl)yne under high temperature conditions with diphenyl ether as a solvent to generate compound 7 with a six-membered ring (benzene ring) central structure. Compound 7 underwent a Suzuki coupling reaction with ethyl phenylboronic acid to generate compound 8. Compound 8 was hydrolyzed under alkaline conditions to give H4BDQDA-t Bu ligand.
[0012] Furthermore, H4BDQDA-OCH3 was obtained through the following method:
[0013] p-Methoxyphenylacetic acid was dissolved in anhydrous dichloromethane and reacted with a dichloromethane solution containing DCC and DMAP to give compound 9. Compound 9 was reacted with 1,2-bis(4-bromophenyl)ethane-1,2-dione under alkaline conditions to generate compound 10 with a five-membered ring central structure. Compound 10 was reacted with di(4-bromophenyl)yne under high temperature conditions with diphenyl ether as solvent to generate compound 11 with a six-membered ring (benzene ring) central structure. Compound 11 was reacted with ethyl phenylboronic acid via a Suzuki coupling reaction to generate compound 12. Compound 12 was hydrolyzed under alkaline conditions to give the H4BDQDA-OCH3 ligand.
[0014] Furthermore, H4BDQDA-OH is obtained through the following method:
[0015] p-Methoxyphenylacetic acid was dissolved in anhydrous dichloromethane and reacted with a dichloromethane solution containing DCC and DMAP to give compound 9. Compound 9 was reacted with 1,2-bis(4-bromophenyl)ethane-1,2-dione under alkaline conditions to generate compound 10 with a five-membered ring central structure. Compound 10 was reacted with di(4-bromophenyl)yne under high temperature conditions with diphenyl ether as solvent to generate compound 11 with a six-membered ring (benzene ring) central structure. Compound 11 was reacted with ethyl phenylboronic acid via a Suzuki coupling reaction to generate compound 12. Compound 12 was dissolved in anhydrous dichloromethane and reacted with a dichloromethane solution containing BBr3 under nitrogen protection and dry ice + isopropanol conditions to give the H4BDQDA-OH ligand.
[0016] Furthermore, H4BDQDA-NO2 is obtained through the following method:
[0017] p-Nitrophenylacetic acid was dissolved in anhydrous dichloromethane and reacted with a dichloromethane solution containing DCC and DMAP to give compound 13. Compound 13 was reacted with 1,2-bis(4-bromophenyl)ethane-1,2-dione under alkaline conditions to generate compound 14 with a five-membered ring central structure. Compound 14 was reacted with di(4-bromophenyl)yne under high temperature conditions with diphenyl ether as solvent to generate compound 15 with a six-membered ring (benzene ring) central structure. Compound 15 was reacted with ethyl phenylboronic acid via a Suzuki coupling reaction to generate compound 16. Compound 16 was hydrolyzed under alkaline conditions to give the H4BDQDA-NO2 ligand.
[0018] Furthermore, H4BDQDA-NH2 is obtained through the following method:
[0019] p-Nitrophenylacetic acid was dissolved in anhydrous dichloromethane and reacted with a dichloromethane solution containing DCC and DMAP to give compound 13. Compound 13 was reacted with 1,2-bis(4-bromophenyl)ethane-1,2-dione under alkaline conditions to generate compound 14 with a five-membered ring central structure. Compound 14 was reacted with di(4-bromophenyl)yne under high temperature conditions with diphenyl ether as solvent to generate compound 15 with a six-membered ring (benzene ring) central structure. Compound 15 was reacted with anhydrous ethanol containing HCl and SnCl2 to give compound 17. Compound 17 was reacted with ethyl phenylboronic acid via a Suzuki coupling reaction to generate compound 18. Compound 18 was hydrolyzed under alkaline conditions to give the H4BDQDA-NH2 ligand.
[0020] A second aspect of this invention is to provide the application of directionally modifiable hexabenzoxyl Zr-MOFs in photocatalytic CO2 reduction.
[0021] Furthermore, the application includes the following steps: S1: transferring MOF materials to a Soxhlet extractor and extracting them using acetone as a solvent, followed by activation of the MOF materials;
[0022] S2: The activated MOFs are added to water containing TEOA and ultrasonically dispersed. Before light irradiation, N2 and CO2 gases are introduced to remove interfering gases. The temperature is maintained at a certain level, and the liquid and gaseous products in the product are quantitatively analyzed. The MOF catalyst after photocatalytic reaction is centrifuged, dried, weighed, and then put into the next photocatalytic cycle reaction.
[0023] The method for synthesizing directionally modifiable hexabenzoxyl Zr-MOFs prepared in this invention is simple and highly stable. It can be used for photocatalytic CO2 reduction reactions, and the prepared series of Zr-MOFs exhibits a wide, tunable bandgap, making it an excellent photocatalyst.
[0024] Compared with the prior art, the present invention has the following advantages:
[0025] 1. This invention, by combining pre-modification and post-synthetic cyclization, for the first time simultaneously introduces the substituents and large conjugated structures of the system into a long-range ordered framework, laying the foundation for the further application of hexabenzokeratyl MOFs in the field of photocatalysis.
[0026] 2. Among the 12 synthesized MOFs materials with the same topology and metal nodes, the adjustable bandgap value can reach 1.41 eV, which is among the top reported in the current research on adjusting the bandgap value of crystalline porous materials.
[0027] 3. The introduction of different substituents has significantly altered the generation and migration of photogenerated electrons in MOFs. Compared to the non-directionally modifiable hexabenzoxyl MOFs (PCN-136), the series of MOFs designed in this invention are of greater exploratory and practical significance. Attached Figure Description
[0028] Figure 1 is a schematic diagram of the steps for synthesizing the H4BDQDA-H(L1) ligand in this invention.
[0029] Figure 2 shows the H4BDQDA- in this invention. t A schematic diagram illustrating the steps involved in the synthesis of Bu(L2) ligands.
[0030] Figure 3 is a schematic diagram of the steps for synthesizing the H4BDQDA-OCH3(L3) ligand in this invention.
[0031] Figure 4 is a schematic diagram of the steps for synthesizing the H4BDQDA-OH(L4) ligand in this invention.
[0032] Figure 5 is a schematic diagram of the steps for synthesizing the H4BDQDA-NO2(L5) ligand in this invention.
[0033] Figure 6 is a schematic diagram of the steps for synthesizing the H4BDQDA-NH2(L6) ligand in this invention.
[0034] Figure 7 is a schematic diagram of the synthesis and topology of the directionally modifiable hexabenzoxyl MOFs synthesized in this invention.
[0035] Figure 8 is the XRD pattern of the directionally modifiable hexabenzoxyl MOFs synthesized in this invention. Detailed Implementation
[0036] The technical solution of the present invention will be further described below with reference to the accompanying drawings.
[0037] The method for preparing directionally modifiable hexabenzoxyl Zr-MOFs provided by this invention includes the following steps:
[0038] (1) The present invention first prepared H4BDQDA-R(R=(-NO2,-H,- t Bu, -OCH3, -OH and -NH2) ligands.
[0039] (2) Take 10 mg of H3BTB and 15 mg of H4BDQDA-R (R=(-NO2,-H,-) obtained in step (1) tBu, -OCH3, -OH and -NH2) ligands, 30 mg ZrCl4 and 0.6 g benzoic acid were added to a 5 mL glass bottle containing 3 mL N,N-dimethylformamide (DMF). The mixture was stirred thoroughly to dissolve the reactants. The glass bottle was placed in a 120 °C oven and reacted for 72 h to form a crystalline product. The precise structure was determined by three-dimensional microelectron diffraction (3DED).
[0040] (3) The crystalline product from step (2) is collected by centrifugation and washed three times with fresh DMF and acetone to obtain six Zr-MOFs with the same topological network.
[0041] (4) Further, 0.05 g of Zr-MOFs obtained in step (3) was added to a 2 mL mixed solution of CH3NO2 + CH2Cl2 (V / V = 1:3) containing 0.144 g FeCl3, and the solution was stirred for 2 h under nitrogen protection. The resulting black crystals were washed with methanol until the filtrate was colorless, and their precise structure was determined by three-dimensional microelectron diffraction (3DED).
[0042] The following example gives H4BDQDA-R(R=(-NO2,-H,- t Preparation method of Bu, -OCH3, -OH and -NH2) ligands.
[0043] Example 1: Synthesis of H4BDQDA-H(L1) ligand. Step 1: Weigh 2.10 g of compound 1 and 3.68 g of 1,2-bis(4-bromophenyl)ethane-1,2-dione into a 250 mL three-necked flask. Under nitrogen protection, add 120 mL of anhydrous ethanol. Stir at 80 °C for 30 min, then add 40 mL of anhydrous ethanol solution containing 0.28 g KOH. Continue stirring for 48 h. After the reaction is complete, cool the reaction solution at 0 °C for 30 min, filter and dry to obtain 3.30 g of purple-red solid product 2 (yield 61%). Step 2: Weigh 5.42 g of compound 2, 3.36 g of 1,2-bis(4-bromophenyl)ethyne, and 15.0 g of diphenyl ether into a 250 mL flask. Heat the mixture at 260 °C for 48 h. After the reaction is complete and cooled to room temperature, add 200 mL of anhydrous methanol. Filter the precipitated solid and wash the product with 200 mL of anhydrous methanol. Dry the product to obtain a light pink product 3 (yield 69%). Step 3: Weigh 4.25 g of compound 3, 5.82 g of (4-(ethoxycarbonyl)phenyl)boronicacid, 13.04 g of Cs₂CO₃, and 0.58 g of Pd(PPh₃)₄ into a 500 mL three-necked flask. Under nitrogen protection, add 300 mL of anhydrous dioxane as the reaction solvent and react at 85 °C for 72 h. After the reaction was completed and cooled to room temperature, dioxane was removed by rotary evaporation under reduced pressure. The solid was extracted with dichloromethane and water, and the organic phase was rotary evaporated to remove dichloromethane, yielding a crude product. The crude product was washed with 200 mL of anhydrous ethanol to remove excess ethyl phenylboronic acid and other byproducts. The final sample was subjected to rapid column chromatography with dichloromethane to give 4.23 g of colorless product 4 (75%). Fourth step: 3.38 g of compound 4 was weighed and dissolved in 60 mL of tetrahydrofuran. The solution was transferred to a 250 mL flask, and 80 mL of deionized water containing 2.4 g of NaOH was added. The reaction was carried out at 65 °C for 48 h. After the reaction was completed, tetrahydrofuran was removed by vacuum filtration. 6 M HCl solution was added to adjust the pH to 2. The filtered solid was washed with water to remove excess NaCl and dried under vacuum to give 2.70 g of colorless solid H4BDQDA-H (yield 89%).
[0044] Example 2: H4BDQDA- tSynthesis of Bu(L2) ligands. Step 1: 3.84 g of p-tert-butylphenylacetic acid was dissolved in anhydrous dichloromethane and transferred to a 250 mL flask. A dichloromethane solution containing 4.12 g of DCC and 0.61 g of DMAP was slowly added dropwise. The reaction was carried out at room temperature for 24 h. The dichloromethane in the filtrate was removed by rotary evaporation. The crude product was purified by column chromatography (PE:EA = 5:1) to give 4.26 g of white compound 5 (yield 66%). Step 2: Weigh 3.22 g of compound 5 and 3.68 g of 1,2-bis(4-bromophenyl)ethane-1,2-dione into a 250 mL three-necked flask. Under nitrogen protection, add 120 mL of anhydrous ethanol and stir at 80 °C for 30 min. Then add 40 mL of anhydrous ethanol solution containing 0.28 g KOH and continue stirring for 48 h. After the reaction is complete, cool the reaction solution at 0 °C for 30 min, filter and dry to obtain 3.85 g of purple-red solid product 6 (yield 59%). Step 3: Weigh 6.54 g of compound 6, 3.36 g of 1,2-bis(4-bromophenyl)ethyne, and 15.0 g of diphenyl ether into a 250 mL flask. Heat the mixture at 260 °C for 48 h. After the reaction is complete and cooled to room temperature, add 200 mL of anhydrous methanol. Filter the precipitated solid and wash the product with 200 mL of anhydrous methanol. Dry the product to obtain 7.12 g of light pink product 7 (yield 74%). Step 4: Weigh 4.81 g of compound 7, 5.82 g of (4-(ethoxycarbonyl)phenyl)boronicacid, 13.04 g of Cs₂CO₃, and 0.58 g of Pd(PPh₃)₄ into a 500 mL three-necked flask. Under nitrogen protection, add 300 mL of anhydrous dioxane as the reaction solvent and react at 85 °C for 72 h. After the reaction was completed and cooled to room temperature, dioxane was removed by rotary evaporation under reduced pressure. The solid was extracted with dichloromethane and water, and the organic phase was rotary evaporated to remove dichloromethane, yielding a crude product. The crude product was washed with 200 mL of anhydrous ethanol to remove excess ethyl phenylboronic acid and other byproducts. The final sample was subjected to rapid column chromatography with dichloromethane to give 4.34 g of colorless product 8 (70% yield). Step 5: 3.72 g of compound 8 was weighed and dissolved in 60 mL of tetrahydrofuran. The solution was transferred to a 250 mL flask, and 80 mL of deionized water containing 2.4 g of NaOH was added. The reaction was carried out at 65 °C for 48 h. After the reaction was completed, tetrahydrofuran was removed by vacuum filtration. 6 M HCl solution was added to adjust the pH to 2. The solid obtained by vacuum filtration was washed with water to remove excess NaCl, and dried under vacuum to give 2.77 g of colorless solid H4BDQDA- t Bu (yield 82%).
[0045] Example 3: Ligand synthesis of H4BDQDA-OCH3(L3). Step 1: 3.32 g of p-methoxyphenylacetic acid was dissolved in anhydrous dichloromethane and transferred to a 250 mL flask. A dichloromethane solution containing 4.12 g of DCC and 0.61 g of DMAP was slowly added dropwise. The reaction was carried out at room temperature for 24 h. The dichloromethane in the filtrate was removed by rotary evaporation. The crude product was purified by column chromatography (PE:EA = 5:1) to give 2.87 g of white compound 9 (yield 53%). Step 2: Weigh 2.70 g of compound 9 and 3.68 g of 1,2-bis(4-bromophenyl)ethane-1,2-dione into a 250 mL three-necked flask. Under nitrogen protection, add 120 mL of anhydrous ethanol and stir at 80 °C for 30 min. Then add 40 mL of anhydrous ethanol solution containing 0.28 g KOH and continue stirring for 48 h. After the reaction is complete, cool the reaction solution at 0 °C for 30 min, filter and dry to obtain 4.10 g of purple-red solid product 10 (yield 68%). Step 3: Weigh 6.03 g of compound 10, 3.36 g of 1,2-bis(4-bromophenyl)ethyne, and 15.0 g of diphenyl ether into a 250 mL flask. Heat the mixture at 260 °C for 48 h. After the reaction is complete and cooled to room temperature, add 200 mL of anhydrous methanol. Filter the precipitated solid and wash the product with 200 mL of anhydrous methanol. Dry the product to obtain 6.37 g of light pink product 11 (70% yield). Step 4: Weigh 4.55 g of compound 11, 5.82 g of (4-(ethoxycarbonyl)phenyl)boronicacid, 13.04 g of Cs₂CO₃, and 0.58 g of Pd(PPh₃)₄ into a 500 mL three-necked flask. Under nitrogen protection, add 300 mL of anhydrous dioxane as the reaction solvent and react at 85 °C for 72 h. After the reaction was completed and cooled to room temperature, dioxane was removed by rotary evaporation under reduced pressure. The solid was extracted with dichloromethane and water, and the organic phase was rotary evaporated to remove dichloromethane, yielding a crude product. The crude product was washed with 200 mL of anhydrous ethanol to remove excess ethyl phenylboronic acid and other byproducts. The final sample was subjected to rapid column chromatography with dichloromethane:ethyl acetate = 15:1 to give 4.39 g of colorless product 12 (yield 75%). Fifth step: 3.56 g of compound 12 was weighed and dissolved in 60 mL of tetrahydrofuran. The solution was transferred to a 250 mL flask, and 80 mL of deionized water containing 2.4 g of NaOH was added. The reaction was carried out at 65 °C for 48 h. After the reaction was completed, tetrahydrofuran was removed by vacuum filtration. 6 M HCl solution was added to adjust the pH to 2. The solid obtained by vacuum filtration was washed with water to remove excess NaCl, and dried under vacuum to give 2.71 g of colorless solid H4BDQDA-OCH3 (yield 84%).
[0046] Example 4: Ligand synthesis of H4BDQDA-OH(L4). The first four steps of this ligand synthesis are consistent with the first four steps of the H4BDQDA-OCH3(L3) coordination. Step 5: 3.56 g of compound 12 was weighed and dissolved in 50 mL of anhydrous dichloromethane. Then, under nitrogen protection and at a temperature of -78 °C (dry ice + isopropanol), 20 mL of BBr3 (10 molar equivalent) dichloromethane solution was added dropwise. After the reaction proceeded for 48 h, 200 mL of deionized water was added to quench the reaction. The mixture was filtered to obtain a light brown solid, which was washed with 200 mL of deionized water and dried under vacuum to obtain 2.89 g of the light brown product H4BDQDA-OH (yield 92%).
[0047] Example 5: Ligand synthesis of H4BDQDA-NO2(L5). Step 1: 3.62 g of p-nitrobenzeneacetic acid was weighed and dissolved in anhydrous dichloromethane. The solution was then transferred to a 250 mL flask, and a dichloromethane solution containing 4.12 g of DCC and 0.61 g of DMAP was slowly added dropwise. The reaction was carried out at room temperature for 24 h. Dichloromethane was removed from the filtrate by rotary evaporation. The crude product was purified by column chromatography (dichloromethane as eluent) to give 2.52 g of white compound 13 (yield 42%). Step 2: Weigh 3.00 g of compound 13 and 3.68 g of 1,2-bis(4-bromophenyl)ethane-1,2-dione into a 250 mL three-necked flask. Under nitrogen protection, add 120 mL of anhydrous ethanol and stir at 80 °C for 30 min. Then add 40 mL of anhydrous ethanol solution containing 0.28 g KOH and continue stirring for 48 h. After the reaction is complete, cool the reaction solution at 0 °C for 30 min, filter and dry to obtain 2.40 g of purple-red solid product 14 (yield 38%). Step 3: Weigh 6.32 g of compound 14, 3.36 g of 1,2-bis(4-bromophenyl)ethyne, and 15.0 g of diphenyl ether into a 250 mL flask. Heat the mixture at 260 °C for 48 h. After the reaction is complete and cooled to room temperature, add 200 mL of anhydrous methanol. Filter the precipitated solid and wash the product with 200 mL of anhydrous methanol. Dry the product to obtain 3.95 g of yellow-brown product 15 (yield 42%). Step 4: Weigh 4.70 g of compound 15, 5.82 g of (4-(ethoxycarbonyl)phenyl)boronicacid, 13.04 g of Cs₂CO₃, and 0.58 g of Pd(PPh₃)₄ into a 500 mL three-necked flask. Under nitrogen protection, add 300 mL of anhydrous dioxane as the reaction solvent and react at 85 °C for 72 h. After the reaction was completed and cooled to room temperature, dioxane was removed by rotary evaporation under reduced pressure. The solid was extracted with dichloromethane and water, and the organic phase was rotary evaporated to remove dichloromethane, yielding a crude product. The crude product was washed with 200 mL of anhydrous ethanol to remove excess ethyl phenylboronic acid and other byproducts. The final sample was subjected to column chromatography with dichloromethane:ethyl acetate (8:1 ratio) to give 4.69 g of dark brown product 16 (77% yield). Fifth step: 3.65 g of compound 16 was weighed and dissolved in 60 mL of tetrahydrofuran. The solution was transferred to a 250 mL flask, and 80 mL of deionized water containing 2.4 g of NaOH was added. The reaction was carried out at 65 °C for 48 h. After the reaction was completed, tetrahydrofuran was removed by vacuum filtration. 6 M HCl solution was added to pH 2, and the filtered solid was washed with water to remove excess NaCl. After vacuum drying, 3.05 g of brown solid H4BDQDA-NO2 (92% yield) was obtained.
[0048] Example 6: Synthesis of ligands for H4BDQDA-NH2(L6). The first three steps of this ligand synthesis are consistent with the first three steps of the synthesis of the ligand for H4BDQDA-NO2(L5). Step 4: 1.50 g of compound 15 was weighed and added to a flask, followed by 150 mL of anhydrous ethanol containing 8 mL of HCl and 1.48 g of SnCl2. The reaction was carried out under nitrogen protection and at 85 °C for 72 h. The product was extracted with EA and H2O, and the organic phase was obtained by rotary evaporation, yielding a brown compound 17 (72% yield). Step 5: 4.40 g of compound 17, 5.82 g of (4-(ethoxycarbonyl)phenyl)boronicacid, 13.04 g of Cs2CO3 and 0.58 g of Pd(PPh3)4 were weighed and added to a 500 mL three-necked flask. Under nitrogen protection, 300 mL of anhydrous dioxane was added as a reaction solvent, and the reaction was carried out at 85 °C for 72 h. After the reaction was completed and cooled to room temperature, dioxane was removed by rotary evaporation under reduced pressure. The solid was extracted with dichloromethane and water, and the organic phase was rotary evaporated to remove dichloromethane, yielding a crude product. The crude product was washed with 200 mL of anhydrous ethanol to remove excess ethyl phenylboronic acid and other byproducts. The final sample was subjected to column chromatography with dichloromethane:ethyl acetate = 6:1 to give 3.94 g of dark brown product 18 (yield 68%). Step 6: 3.47 g of compound 18 was weighed and dissolved in 60 mL of tetrahydrofuran. The solution was transferred to a 250 mL flask, and 80 mL of deionized water containing 2.4 g of NaOH was added. The reaction was carried out at 65 °C for 48 h. After the reaction was completed, tetrahydrofuran was removed by vacuum filtration. 6 M HCl solution was added to pH = 2. The solid obtained by vacuum filtration was washed with water to remove excess NaCl, and dried under vacuum to give 2.76 g of brown solid H4BDQDA-NH2 (yield 88%).
[0049] Comparative Example 1: In the literature J. Am. Chem. Soc. 2019, 141, 2054-2060, Zhou et al. reported a method for synthesizing hexabenzoctomyl MOFs with high symmetry. Due to the high symmetry of the HCHC ligand, PCN-136 performs poorly in carrier separation, which is significantly inferior to the directionally modifiable hexabenzoctomyl MOFs synthesized in this invention.
[0050] Comparative Example 2: In the literature Chem. Rev. 2022, 122, 14554-14593, Miao et al. reviewed the Scholl reaction of some compounds with different substituents. However, due to steric hindrance and solubility, these representative Scholl reactions are usually difficult to carry out in long-range ordered MOF materials. Compared with the method of combining pre-modification and post-synthetic cyclization used in this invention, it also has obvious disadvantages and shortcomings.
[0051] The provided figures illustrate the following issues or effects:
[0052] Figure 1 illustrates the specific steps for synthesizing the H4BDQDA-H(L1) ligand in this invention, and provides the specific molecular structural formulas of compounds 1, 2, 3, 4 and the H4BDQDA-H(L1) ligand mentioned in Example 1.
[0053] Figure 2 illustrates the H4BDQDA- in this invention. t The specific steps for synthesizing Bu(L2) ligands are given, and compounds 5, 6, 7, 8 and H4BDQDA- mentioned in Example 2 are also provided. t The specific molecular structure of Bu(L2).
[0054] Figure 3 illustrates the specific steps of the synthesis of H4BDQDA-OCH3(L3) ligand in this invention, and provides the specific molecular structural formulas of compounds 9, 10, 11, 12 and H4BDQDA-OCH3(L3) mentioned in Example 3.
[0055] Figure 4 illustrates the specific steps for synthesizing the H4BDQDA-OH(L4) ligand in this invention, and provides the specific molecular structure of H4BDQDA-OH(L4) mentioned in Example 4.
[0056] Figure 5 illustrates the specific steps for the synthesis of the H4BDQDA-NO2(L5) ligand in this invention, and provides the specific molecular structural formulas of compounds 13, 14, 15, 16 and H4BDQDA-NO2(L5) mentioned in Example 5.
[0057] Figure 6 illustrates the specific steps of the synthesis of the H4BDQDA-NH2(L6) ligand in this invention, and provides the specific molecular structural formulas of compounds 17, 18 and H4BDQDA-NH2(L6) mentioned in Example 6.
[0058] Figure 7 illustrates the synthesis and topology of the columnar Zr-MOFs mentioned in this invention. Figure (d) shows the precise structure resolved by 3DED testing, fully demonstrating the successful synthesis of the designed columnar Zr-MOFs.
[0059] Figure 8 illustrates the hexabenzoxyl Zr-MOFs (af, in sequence H, ...) synthesized in this invention with different substituents. t Substituents (such as Bu, OH, OCH3, NO2, and NH2) exhibit high crystallinity and phase purity.
[0060] Application example:
[0061] The hexabenzoxyl metal-organic framework obtained in this invention can be applied in the field of photocatalytic CO2 reduction. The specific steps are as follows:
[0062] S1: Transfer the freshly prepared MOF material to a Soxhlet extractor and extract with acetone as the solvent for 72 h. For MOF samples after the Scholl reaction, ICP-OES testing should also be performed to rule out the influence of Fe on the photocatalytic reaction. Then, activate the desired MOF material at 100 °C for 12 h.
[0063] S2: In the photocatalytic reaction system, a 300W Xe lamp equipped with a 420nm wavelength filter was used to simulate the generation of visible light. 8mg of activated MOFs were weighed and added to 5mL of water containing a certain volume fraction of TEOA, and ultrasonically dispersed for 10min. Before illumination, N2 and CO2 gases were passed through for 30min and 30min respectively to remove interfering gases. To ensure catalyst suspension and full participation in the photocatalytic reaction, the stirring speed of the magnetic stirrer was fixed at 400rpm. The temperature of the reaction system was maintained at 15℃ using a water-cooling device (CCA-420). Ion chromatography (EcoIC) was used to analyze the liquid product HCOO in the product. - Quantitative analysis was performed using gas chromatography (GC-2030N, 230V). In the cycle stability test, the MOF catalyst after the photocatalytic reaction was centrifuged, dried, weighed, and then added to the next photocatalytic cycle.
[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.
Claims
1. A method for preparing a directionally-modifiable hexa-benzocoronene metal-organic framework, characterized by: H3BTB, H4BDQDA-R ligand, ZrCl4 and benzoic acid were added to N,N-dimethylformamide (DMF), and the reactants were stirred thoroughly to dissolve them. After the reaction, crystalline products Zr-MOFs were obtained. The obtained crystalline products were collected by centrifugation and washed with fresh DMF and acetone to obtain Zr-MOFs with the same topological network. In H4BDQDA-R, R = -NO2, -H, - t Bu, -OCH3, -OH and -NH2, having the following structure:
2. The preparation method according to claim 1, characterized in that, H4BDQDA-H is obtained through the following method: Dibenzyl ketone was reacted with 1,2-bis(4-bromophenyl)ethane-1,2-dione under alkaline conditions to generate compound 2 with a five-membered ring central structure. Compound 2 was then reacted with di(4-bromophenyl)yne under high temperature conditions with diphenyl ether as solvent to generate compound 3 with a six-membered ring (benzene ring) central structure. Compound 3 then underwent a Suzuki coupling reaction with ethyl phenylboronic acid to generate compound 4. Finally, compound 4 was hydrolyzed under alkaline conditions to obtain the H4BDQDA-H ligand.
3. The preparation method according to claim 1, characterized in that, H4BDQDA- t Bu was obtained by the following method: Compound 5 was obtained by dissolving p-tert-butylphenylacetic acid in anhydrous dichloromethane and reacting with a dichloromethane solution containing DCC and DMAP. Compound 6 was obtained by reacting compound 5 with 1,2-bis(4-bromophenyl)ethane-1,2-dione under basic conditions. Compound 7 was obtained by reacting compound 6 with di(4-bromophenyl)acetylene under high temperature conditions with diphenyl ether as the solvent. Compound 8 was obtained by Suzuki coupling reaction of compound 7 with phenylboronic acid ethyl ester. Compound H4BDQDA was obtained by hydrolysis of compound 8 under basic conditions. t Bu ligand.
4. The method of claim 1 wherein the step of forming the first and second layers comprises the step of: H4BDQDA-OCH3 was obtained through the following method: p-Methoxyphenylacetic acid was dissolved in anhydrous dichloromethane and reacted with a dichloromethane solution containing DCC and DMAP to give compound 9. Compound 9 was reacted with 1,2-bis(4-bromophenyl)ethane-1,2-dione under alkaline conditions to generate compound 10 with a five-membered ring central structure. Compound 10 was reacted with di(4-bromophenyl)yne under high temperature conditions with diphenyl ether as solvent to generate compound 11 with a six-membered ring (benzene ring) central structure. Compound 11 was reacted with ethyl phenylboronic acid via a Suzuki coupling reaction to generate compound 12. Compound 12 was hydrolyzed under alkaline conditions to give the H4BDQDA-OCH3 ligand.
5. The method of claim 1 wherein the step of forming the first and second layers comprises the step of: H4BDQDA-OH is obtained by the following method: p-Methoxyphenylacetic acid was dissolved in anhydrous dichloromethane and reacted with a dichloromethane solution containing DCC and DMAP to give compound 9. Compound 9 was reacted with 1,2-bis(4-bromophenyl)ethane-1,2-dione under alkaline conditions to generate compound 10 with a five-membered ring central structure. Compound 10 was reacted with di(4-bromophenyl)yne under high temperature conditions with diphenyl ether as solvent to generate compound 11 with a six-membered ring (benzene ring) central structure. Compound 11 was reacted with ethyl phenylboronic acid via a Suzuki coupling reaction to generate compound 12. Compound 12 was dissolved in anhydrous dichloromethane and reacted with a dichloromethane solution containing BBr3 under nitrogen protection and dry ice + isopropanol conditions to give the H4BDQDA-OH ligand.
6. The method of claim 1 wherein the step of forming the first and second layers comprises the step of: H4BDQDA-NO2 is obtained through the following method: p-Nitrophenylacetic acid was dissolved in anhydrous dichloromethane and reacted with a dichloromethane solution containing DCC and DMAP to give compound 13. Compound 13 was reacted with 1,2-bis(4-bromophenyl)ethane-1,2-dione under alkaline conditions to generate compound 14 with a five-membered ring central structure. Compound 14 was reacted with di(4-bromophenyl)yne under high temperature conditions with diphenyl ether as solvent to generate compound 15 with a six-membered ring (benzene ring) central structure. Compound 15 was reacted with ethyl phenylboronic acid via a Suzuki coupling reaction to generate compound 16. Compound 16 was hydrolyzed under alkaline conditions to give the H4BDQDA-NO2 ligand.
7. The preparation method according to claim 1, characterized in that, H4BDQDA-NH2 is obtained through the following method: p-Nitrophenylacetic acid was dissolved in anhydrous dichloromethane and reacted with a dichloromethane solution containing DCC and DMAP to give compound 13. Compound 13 was reacted with 1,2-bis(4-bromophenyl)ethane-1,2-dione under alkaline conditions to generate compound 14 with a five-membered ring central structure. Compound 14 was reacted with di(4-bromophenyl)yne under high temperature conditions with diphenyl ether as solvent to generate compound 15 with a six-membered ring (benzene ring) central structure. Compound 15 was reacted with anhydrous ethanol containing HCl and SnCl2 to give compound 17. Compound 17 was reacted with ethyl phenylboronic acid via a Suzuki coupling reaction to generate compound 18. Compound 18 was hydrolyzed under alkaline conditions to give the H4BDQDA-NH2 ligand.
8. The application of the directionally modifiable hexabenzoxyl metal-organic framework as described in claim 1 in photocatalytic CO2 reduction.
9. The application according to claim 8, characterized in that: S1: the MOF material is transferred to a Soxhlet extractor and extracted using acetone as a solvent, and then the MOF material is activated; S2: The activated MOFs are added to water containing TEOA and ultrasonically dispersed. Before light irradiation, N2 and CO2 gases are introduced to remove interfering gases. The temperature is maintained at a certain level, and the liquid and gaseous products in the product are quantitatively analyzed. The MOF catalyst after photocatalytic reaction is centrifuged, dried, weighed, and then put into the next photocatalytic cycle reaction.