A pickering emulsion stabilized by a dopamine ligand-doped metal-organic framework uiO-66-nh2@da and application thereof
Patent Information
- Application Number
- CN202611088574.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-22
- Publication Date
- 2026-10-27
Smart Images
Figure CN122974367A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalytic synthesis technology, specifically relating to a dopamine ligand-doped metal-organic framework UiO-66-NH2@DA-stabilized Pickering emulsion and its application. Background Technology
[0002] Metal-organic frameworks (MOFs) are promising crystalline porous materials composed of metal clusters and organic linkers connected by coordination bonds. MOFs possess advantages such as good thermal stability, large specific surface area, and diverse and modifiable structures. Therefore, MOFs show great potential in organic catalysis and gas adsorption. UiO-66-NH2, a typical representative of MOFs, possesses a regular porous structure when constructed with a single ligand, but suffers from limitations in the type and number of catalytic active sites, significantly restricting its adaptability to catalytic reactions and catalytic efficiency. Therefore, synthesizing UiO-66-NH2@DA by doping with dopamine ligands can increase the variety and number of acid-base active sites while retaining the original porous crystalline structure, representing an important technical approach to improve the catalytic performance and applicability of MOF-based catalysts.
[0003] Benzylmalonium derivatives (BMDs) possess excellent chemical and biological activities, making them highly valuable in the pharmaceutical, dye, and pesticide fields. Therefore, finding green, energy-saving, and economical methods for BMD synthesis is crucial. Serial reaction synthesis processes can achieve continuous substrate transformation within a single reaction system, eliminating intermediate product separation and purification steps, significantly reducing synthesis costs and environmental pollution, making them a highly promising technological path in the field of fine organic synthesis. The deacetalization-Knoevenagel reaction, as a typical Serial reaction, is a highly efficient one-pot transformation route for BMD preparation. Developing novel catalytic systems suitable for this reaction has practical research significance.
[0004] Pickering emulsions are formed by the self-assembly of solid microparticles at the interface of two immiscible liquid phases, effectively inhibiting emulsion droplet aggregation and constructing a large number of microscale reaction units. Compared with traditional emulsions, Pickering emulsions have advantages such as low toxicity and high stability, providing a good interfacial dispersion environment for MOFs, fully exposing catalytic active sites, and carrying out catalytic reactions by loading active centers at the liquid-liquid interface, thus possessing the dual advantages of multiphase tandem catalysis and interfacial catalysis. Summary of the Invention
[0005] The purpose of this invention is to provide a dopamine ligand-doped metal-organic framework UiO-66-NH2@DA stabilized Pickering emulsion and its application. The UiO-66-NH2@DA composite material not only effectively solves the problems of low catalytic activity and poor cycling effect of single UiO-66-NH2, but also enhances the catalytic performance of the composite material with the prepared Pickering emulsion, bringing a new technical method for the efficient catalytic deacetalization-Knoevenagel tandem reaction.
[0006] The technical solution adopted in this invention is:
[0007] A metal-organic framework UiO-66-NH2@DA doped with dopamine ligands, the preparation method of which includes the following steps:
[0008] 1) Dissolve dopamine hydrochloride (DA) and ZrCl4 in N,N-dimethylformamide and stir at room temperature for 6 h to obtain a precursor solution;
[0009] 2) Subsequently, 2-amino-terephthalic acid was added to the precursor solution, along with concentrated HCl and deionized water. After stirring at room temperature for 20 min, the mixture was transferred to a polytetrafluoroethylene-lined stainless steel autoclave for heating and reaction. After the reaction was completed, the mixture was naturally cooled to room temperature, centrifuged, and washed three times sequentially with N,N-dimethylformamide and ethanol. The washed product was then transferred to ethanol, soaked overnight, and centrifuged to collect the precipitate powder. Subsequently, the powder was vacuum dried and activated to obtain UiO-66-NH2@DA.
[0010] Furthermore, in the above-mentioned method for preparing a metal-organic framework UiO-66-NH2@DA doped with dopamine ligand, in step 1), DA:ZrCl4:N,N-dimethylformamide = 61 mg:300 mg:60 mL.
[0011] Furthermore, in the above-mentioned method for preparing a metal-organic framework UiO-66-NH2@DA doped with dopamine ligand, in step 2), 2-amino-terephthalic acid: precursor solution: concentrated HCl: deionized water = 232 mg: 60 mL: 4 mL: 75 μL.
[0012] Furthermore, in the above-mentioned method for preparing a metal-organic framework UiO-66-NH2@DA doped with a dopamine ligand, in step 2), the heating reaction is carried out at 393 K for 24 h.
[0013] Furthermore, in the above-mentioned method for preparing a metal-organic framework UiO-66-NH2@DA doped with dopamine ligands, in step 2), the vacuum drying and activation is first performed by vacuum drying and activation at 353 K for 6 h, and then by vacuum drying and activation at 383 K for 12-18 h.
[0014] A dopamine ligand-doped metal-organic framework UiO-66-NH2@DA-stabilized picklator emulsion is prepared as follows: Toluene and water are added to the above-mentioned dopamine ligand-doped metal-organic framework UiO-66-NH2@DA, and the mixture is sonicated and shaken vigorously to obtain the UiO-66-NH2@DA-stabilized picklator emulsion.
[0015] Furthermore, the preparation method of the above-mentioned metal-organic framework UiO-66-NH2@DA stabilized with dopamine ligand, wherein UiO-66-NH2@DA:toluene:water = 30 mg:2 mL:3 mL.
[0016] The application of the above-mentioned dopamine ligand-doped metal-organic framework UiO-66-NH2@DA-stabilized Pickering emulsion in the catalytic deacetalization-Knoevenagel tandem reaction is as follows: benzaldehyde dimethyl acetal, malononitrile, and the above-mentioned dopamine ligand-doped metal-organic framework UiO-66-NH2@DA-stabilized Pickering emulsion are reacted in a reaction vessel.
[0017] Furthermore, in the above application, benzaldehyde dimethyl acetal: malononitrile: pickering emulsion = 1 mmol: 1.5 mmol: 5 mL.
[0018] Furthermore, in the above application, the reaction temperature was 353 K and the reaction time was 2.5 h.
[0019] In the UiO-66-NH2@DA-stabilized Pickering emulsion system provided by this invention, the Zr cluster provides abundant Lewis acidic sites, and the phenolic hydroxyl groups in DA provide Brönsted acidic sites. Both catalyze the first step of the deacetalization reaction. The amino groups in the two organic ligands provide Brönsted basic sites to catalyze the second step of the Knoevenagel reaction. The reaction formulas are as follows:
[0020]
[0021] The beneficial effects of this invention are as follows: The UiO-66-NH2@DA composite material provided by this invention, as a catalyst, allows Zr clusters to act as Lewis acidic sites to catalyze the first step of the deacetalization reaction, and amino groups to act as Brönsted basic catalytic sites to catalyze the second step of the tandem reaction, the Knoevenagel reaction. However, the single UiO-66-NH2 material suffers from limited acid-base catalytic sites and poor catalytic efficiency. This invention incorporates dopamine ligands into the Zr metal cluster coordination system, allowing dopamine to coordinate sequentially with the original ligands and become fixed on the Zr active clusters. Introducing dopamine as a ligand increases the variety and number of catalytic sites, thereby improving the variety and number of acid-base bifunctional catalytic sites and significantly enhancing the reaction efficiency of the deacetalization-Knoevenagel reaction. Simultaneously, the dispersion of UiO-66-NH2@DA in an emulsion system forms a stable Pickering emulsion, which greatly increases the contact area between the substrate and the catalyst, further improving catalytic efficiency. Attached Figure Description
[0022] Figure 1 This is an optical microscope image of the UiO-66-NH2@DA stabilized Pickering emulsion prepared according to the present invention.
[0023] Figure 2 This is the X-ray diffraction (PXRD) pattern of UiO-66-NH2 and UiO-66-NH2@DA prepared in this invention.
[0024] Figure 3 These are the infrared spectra (FT-IR) of DA, UiO-66-NH2, and UiO-66-NH2@DA materials.
[0025] Figure 4 These are scanning electron microscope (SEM) images of UiO-66-NH2 (a) and UiO-66-NH2@DA (b) prepared in this invention.
[0026] Figure 5 This is a catalytic activity diagram of the UiO-66-NH2@DA-stabilized Pickering emulsion prepared in this invention after five catalytic cycles. Detailed Implementation
[0027] Example 1: A dopamine ligand-doped metal-organic framework UiO-66-NH2@DA-stabilized Pickering emulsion
[0028] (I) Preparation method
[0029] 1. Preparation of UiO-66-NH2@DA
[0030] 1) Dissolve 61 mg of dopamine hydrochloride (DA) and 300 mg of ZrCl4 in 60 mL of N,N-dimethylformamide and stir at room temperature for 6 h to obtain the precursor solution.
[0031] 2) Subsequently, 232 mg of 2-amino-terephthalic acid was added to 60 mL of precursor solution, along with 4 mL of concentrated HCl and 75 μL of deionized water. After stirring at room temperature for 20 min, the mixture was transferred to a polytetrafluoroethylene-lined stainless steel autoclave and heated at 393 K for 24 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature, centrifuged, and washed three times sequentially with N,N-dimethylformamide and ethanol. The washed product was then transferred to ethanol, soaked overnight, and centrifuged to collect the precipitate powder. Subsequently, the powder was vacuum dried at 353 K and activated for 6 h, and then vacuum dried at 383 K and activated for 15 h to obtain UiO-66-NH2@DA.
[0032] 2. Preparation of UiO-66-NH2@DA stabilized picklion emulsion
[0033] 30 mg of UiO-66-NH2@DA was placed in a vial, and 3 mL of water and 2 mL of toluene were added. The mixture was sonicated for 5 min and then shaken vigorously for 5 min to obtain a stable UiO-66-NH2@DA Pickleriane emulsion.
[0034] (ii) Characterization
[0035] Figure 1 These are optical microscope images of the UiO-66-NH2@DA-stabilized Pickering emulsion prepared according to this invention. Figure 1 It is evident that the stable UiO-66-NH2@DA Picklerin emulsion droplets are uniformly dispersed and of uniform size.
[0036] Figure 2 This is the X-ray diffraction (PXRD) pattern of UiO-66-NH2 and UiO-66-NH2@DA prepared in this invention. Figure 2 It is evident that the diffraction pattern of the material after doping with dopamine ligands is similar to that before doping, indicating that the main framework of UiO-66-NH2 in the synthesized composite material was not destroyed.
[0037] Figure 3 The images show the Fourier Transform Infrared (FT-IR) spectra of DA, UiO-66-NH2, and UiO-66-NH2@DA materials, indicating that UiO-66-NH2@DA material was successfully synthesized.
[0038] Figure 4These are scanning electron microscope (SEM) images of the UiO-66-NH2 (a) and UiO-66-NH2@DA composite materials (b) prepared in this invention. Figure 4 It is evident that the morphology of the UiO-66-NH2@DA composite material is not significantly different from that of UiO-66-NH2, indicating that the material's appearance was not damaged during the modification process.
[0039] Example 2: Application of a dopamine-doped metal-organic framework UiO-66-NH2@DA-stabilized pickering emulsion in catalytic deacetalization-Knoevenagel tandem reaction
[0040] (a) Application Method
[0041] Five mL of UiO-66-NH2@DA-stabilized Pickering emulsion was added to a 10 mL three-necked reaction vessel, followed by the sequential addition of 1.0 mmol benzaldehyde dimethyl acetal and 1.5 mmol malononitrile. The reaction was carried out at 353 K to generate a benzylmalononitrile derivative. The yield of the product was monitored in real time by gas chromatography (GC).
[0042] GC analysis showed that the yield of the reaction gradually increased as the reaction proceeded, reaching 92% after 2.5 hours.
[0043] (II) Recycling of UiO-66-NH2@DA-stabilized Pickering emulsion
[0044] After the reaction was completed, the reaction mixture was centrifuged and filtered to separate it from UiO-66-NH2@DA. The mixture was then washed with ethanol, filtered, and dried. The UiO-66-NH2@DA material was recovered.
[0045] The specific operation of the cyclic experiment: Pickering emulsion was prepared again using the recovered UiO-66-NH2@DA material to catalyze the Deacetalization-Knoevenagel tandem reaction, and the reaction was carried out at 353 K for 2.5 h.
[0046] Experimental results are as follows Figure 5 As shown, Figure 5 The results show that after five cycles of the experiment, the activity of the catalyst UiO-66-NH2@DA did not decrease significantly, and the conversion rate and yield both reached over 90%. This indicates that UiO-66-NH2@DA can be recycled as a catalyst for the Deacetalization-Knoevenagel tandem reaction in the stable Pickleriane emulsion.
Claims
1. A metal-organic framework UiO-66-NH2@DA doped with dopamine ligands, characterized in that, Its preparation method includes the following steps: 1) Dissolve dopamine hydrochloride (DA) and ZrCl4 in N,N-dimethylformamide and stir at room temperature for 6 h to obtain a precursor solution; 2) Subsequently, 2-amino-terephthalic acid was added to the precursor solution, along with concentrated HCl and deionized water. After stirring at room temperature for 20 min, the mixture was transferred to a polytetrafluoroethylene-lined stainless steel autoclave for heating and reaction. After the reaction was completed, the mixture was naturally cooled to room temperature, centrifuged, and washed three times sequentially with N,N-dimethylformamide and ethanol. The washed product was then transferred to ethanol, soaked overnight, and centrifuged to collect the precipitate powder. Subsequently, the powder was vacuum dried and activated to obtain UiO-66-NH2@DA.
2. The metal-organic framework UiO-66-NH2@DA doped with dopamine ligand according to claim 1, characterized in that, In step 1), DA:ZrCl4:N,N-dimethylformamide = 61 mg:300 mg:60 mL.
3. The metal-organic framework UiO-66-NH2@DA doped with dopamine ligand according to claim 1, characterized in that, In step 2), the ratio of 2-amino-terephthalic acid: precursor solution: concentrated HCl: deionized water is 232 mg: 60 mL: 4 mL: 75 μL.
4. The metal-organic framework UiO-66-NH2@DA doped with dopamine ligand according to claim 1, characterized in that, In step 2), the heating reaction is carried out at 393 K for 24 h.
5. The metal-organic framework UiO-66-NH2@DA doped with dopamine ligand according to claim 1, characterized in that, In step 2), the vacuum drying and activation process involves first vacuum drying and activation at 353 K for 6 h, and then vacuum drying and activation at 383 K for 12-18 h.
6. A metal-organic framework UiO-66-NH2@DA stabilized pickering emulsion doped with dopamine ligand, characterized in that, The preparation method is as follows: Toluene and water are added to the metal-organic framework UiO-66-NH2@DA doped with dopamine ligand as described in claim 1, and the mixture is subjected to ultrasonication and vigorous shaking to obtain a UiO-66-NH2@DA-stable Pickering emulsion.
7. A dopamine-doped metal-organic framework UiO-66-NH2@DA stabilized Pickering emulsion according to claim 6, characterized in that, UiO-66-NH2@DA: Toluene: Water = 30 mg: 2 mL: 3 mL.
8. The application of a dopamine-doped metal-organic framework UiO-66-NH2@DA-stabilized pickering emulsion in the catalytic deacetalization-Knoevenagel tandem reaction, characterized in that, The method is as follows: Benzaldehyde dimethyl acetal, malononitrile, and a pickering emulsion stabilized by a metal-organic framework UiO-66-NH2@DA doped with dopamine ligand as described in claim 7 are taken and reacted in a reaction vessel.
9. The application according to claim 8, characterized in that, Benzaldehyde dimethyl acetal: malononitrile: pickering emulsion = 1 mmol: 1.5 mmol: 5 mL.
10. The application according to claim 8, characterized in that, The reaction temperature was 353 K and the reaction time was 2.5 h.