Metal organic framework for synergistic activation conversion of C-H bond and oxygen and preparation method thereof

Abstract

The invention discloses a preparation method of a metal organic framework for synergistic activation conversion of C-H bonds and oxygen, and belongs to the technical field of photocatalytic materials. Ce < 3 + > is used as a metal node, organic dye 9, 10-diphenyl anthracene (DPA) is used as a functional unit, and the Ce-based metal organic framework material Ce-DPA is prepared by coordination of the Ce < 3 + > and the organic dye 9, 10-diphenyl anthracene (DPA). The Ce-based metal organic framework material Ce-DPA has pore channels with moderate sizes and abundant active sites, provides a way for improving reaction activity, and effectively avoids aggregation self-quenching of DPA. Ce-DPA is suitable for catalytic oxidation of various aromatic hydrocarbons, and corresponding ketone products are obtained with selectivity greater than 99%. In addition, Ce-DPA can be recycled five times, the catalytic activity is not reduced, and the stability of the catalyst is good.

Description

Technical Field

[0001] This invention relates to a method for preparing a metal-organic framework for the synergistic activation and transformation of CH bonds and oxygen, belonging to the field of photocatalytic materials technology. Background Technology

[0002] Petroleum contains abundant alkanes, cycloalkanes, and aromatics. Activating their CH bonds involves relatively short reaction steps, thus the conversion of petroleum raw materials into high-value-added organic compounds has attracted great interest from researchers. However, due to the high bond dissociation energy of inert CH bonds, their activation remains a research challenge. Currently, CH bond activation methods mainly include metal catalysis, metal carbene catalysis, and hydrogen atom transfer. Metal catalysis is the most important method for CH bond activation, but its reaction process involves precious metals and toxic reagents. Metal carbene catalysis mainly achieves activation through intermolecular reactions, which inevitably leads to unnecessary electron and energy losses. Therefore, there is an urgent need to develop highly selective and environmentally friendly photocatalytic systems to provide an effective solution for the oxidation of alkanes, cycloalkanes, and aromatics.

[0003] Hydrogen atom transfer (HAT) is an elementary reaction in which hydrogen atoms are extracted from a substrate via a free radical intermediate. This removes the limitation imposed by redox potential and is a relatively simple and direct method for activating CH bonds. Utilizing oxygen as a green terminal oxidant, it provides an opportunity to oxidize CH bonds under mild conditions. As an inexpensive and readily available anthracene dye, 9,10-diphenylanthracene (DPA) has been successfully used to oxidize Ce(III) to Ce(IV). However, its application is greatly limited by its susceptibility to aggregation-induced quenching and photobleaching in homogeneous systems. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, the present invention aims to provide a method for preparing Ce-based metal-organic framework materials for the synergistic activation and transformation of CH bonds and oxygen. This invention successfully synthesizes Ce-based metal-organic frameworks using a solvothermal synthesis method. 3+ The introduction of DPA into MOFs is noteworthy. Importantly, the high oxidation potential of excited-state DPA ensures the high efficiency of the HAT process in activating CH bonds. Under optimized conditions, various aromatic hydrocarbons were used as substrates, and corresponding ketones were obtained under Ce-DPA catalysis with selectivity greater than 99%, successfully expanding the substrate range. Furthermore, Ce-DPA can be recycled five times without loss of selectivity, preventing the release of toxic dyes into the environment. This method represents a promising new approach for uniquely economical and highly selective MOF photocatalysts.

[0005] To achieve the above-mentioned objectives and solve the problems existing in the prior art, the technical solution adopted by the present invention is: a method for preparing Ce-based metal-organic framework materials for the synergistic activation and transformation of CH bonds and oxygen, comprising the following steps: Ce-DPA, a metal-organic framework material, was prepared by coordination of Ce salt with organic linker H4ADIP via a solvothermal method. The structure of H4ADIP is as follows:

[0006] The molar ratio of Ce salt to organic linker H4ADIP is 1:5~15.

[0007] Furthermore, the Ce salt is cerium chloride or cerium nitrate.

[0008] Furthermore, the solvent used in the reaction is selected from... N,N - Dimethylformamide, acetonitrile, N,N The reaction is carried out at least one of dimethylacetamides at a temperature of 80-120°C for 15-60 hours.

[0009] Further, Ce salt and DPA are added to a solvent and sonicated until a suspension is formed. Then, the suspension is transferred to a high-pressure reactor and heated at 80-120°C for 15-60 hours. After centrifugation or filtration, washing, and vacuum drying, Ce-based metal-organic framework material Ce-DPA is obtained.

[0010] Ce-based metal-organic framework materials were prepared using the method described above.

[0011] The Ce-based metal-organic framework material is used in the catalytic activation of indanone to prepare 1-indanone.

[0012] The Ce-based metal-organic framework material is used to catalytically activate indane to prepare 1-indanone under light irradiation, with the light wavelength range being 390~520 nm.

[0013] The beneficial effects of this invention are: a method for preparing Ce-based metal-organic framework materials for the catalytic oxidation of indanthium to 1-indanone and its application, using metallic Ce as the metal node and DPA as the functional unit, the two are coordinated via a solvothermal method to obtain the metal-organic framework material. Compared with existing technologies, this method is milder and easier to synthesize. On the one hand, the introduction of H4ADIP successfully expands the light absorption properties of the parent framework; on the other hand, H4ADIP can oxidize Ce(III) to Ce(IV), thereby generating HAT reagents through the LMCT process. The excellent CH bond activation and oxygen activation properties of Ce-DPA make the oxidation reaction of indanthium possible. This Ce-based metal-organic framework material Ce-DPA has appropriately sized channels and abundant active sites, providing a way to improve reactivity and effectively avoiding the aggregation and self-quenching of DPA. After optimization of reaction conditions, under blue light irradiation, Ce-DPA catalyzed the oxidation of indene to 1-indanone with a selectivity of over 99%, and the catalyst can be stably recycled more than five times, demonstrating good stability and recyclability.

[0014] Metal-organic frameworks (MOFs), composed of ordered connections between organic ligands and inorganic metal ions / cluster nodes, serve as heterogeneous catalysts for various organic transformations. MOFs constructed from polynuclear metal clusters possess abundant active sites and channels, providing a promising approach to enhancing reaction activity. Introducing photosensitive units into MOFs is an effective way to improve photocatalytic activity. This Ce-based metal-organic framework material and method offer new insights for expanding green organic catalysis strategies. Attached Figure Description

[0015] Figure 1 This is the powder X-ray diffraction (PXRD) of Ce-DPA, the target compound in Example 1.

[0016] Figure 2 The image shows the X-ray photoelectron spectroscopy (XPS) of Ce-DPA, the target compound in Example 1, after irradiation.

[0017] Figure 3 This is the X-ray photoelectron spectroscopy (XPS) of the compound Ce-DPA prepared in Example 1 before irradiation.

[0018] Figure 4 The graph shows the yield of the compound Ce-DPA prepared in Example 1 for the catalytic oxidation of indanthium to 1-indanone under light conditions, as a function of time, and the filtration experiment diagram.

[0019] Figure 5 This is a bar chart showing the cyclic yield of the preparation of 1-indanone by the catalytic oxidation of indanthium with compound Ce-DPA prepared in Example 1.

[0020] Figure 6 This is a coordination structure diagram of the compound Ce-DPA prepared in Example 1. Detailed Implementation

[0021] Specifically, a method for preparing cerium-based metal-organic framework materials with highly selective catalytic activation of light alkanes, using Ce... 3+ H4ADIP was used as a metal node and H4ADIP as an organic linker. The two were coordinated via a solvothermal method to prepare Ce-based metal-organic framework material Ce-DPA. The synthetic route is as follows: Ce(NO3)3 + H4ADIP → Ce-DPA The structure of H4ADIP is as follows:

[0022] The structure of Ce-DPA is as follows:

[0023] Some specific steps in the preparation of the Ce-based metal-organic framework materials include: the molar ratio of Ce salt (Ce(NO3)3 or CeCl3) to H4ADIP is selected from 5 to 1:1; and the reaction solvent is selected from... N,N - Dimethylformamide, acetonitrile, N,N The reaction is carried out at least one of dimethylacetamides at a temperature of 80-120°C for 15-60 hours.

[0024] Some specific steps for preparing the Ce-based metal-organic framework material include adding Ce salt (Ce(NO3)3 or CeCl3) and H4ADIP to a solvent and sonicating until a uniform suspension is formed. Then, the suspension is transferred to a high-pressure reactor and heated at 80-120°C for 15-60 hours. After centrifugation or filtration, washing, and vacuum drying, the Ce-based metal-organic framework material Ce-DPA is obtained.

[0025] Some specific steps for preparing the Ce-based metal-organic framework material include adding Ce salt (Ce(NO3)3 or CeCl3) and H4ADIP to DMF and sonicating until a uniform suspension is formed. Then, the suspension is transferred to a high-pressure reactor and heated at 120°C for 54 hours. After centrifugation or filtration, washing, and vacuum drying, the Ce-based metal-organic framework material Ce-DPA is obtained.

[0026] A specific method for preparing Ce-based metal-organic framework materials comprises the following steps: Ce(NO3)3·6H2O (8 mg, 18 μmol) and H4ADIP (4 mg, 5 μmol) were sonicated in DMF (1.5 mL), H2O (0.5 mL), and CH3CN (0.5 mL) until a homogeneous suspension was formed. The suspension was then transferred to a high-pressure reactor lined with polytetrafluoroethylene and heated at 120 °C for 36 hours. After cooling to room temperature, the yellow powder was collected by centrifugation and filtered successively with DMF and ethanol, and washed several times until the supernatant was clear and transparent, with no H4ADIP dye adsorption residue. Finally, the yellow powder was vacuum dried overnight at 100 °C to obtain Ce-based metal-organic framework Ce-DPA.

[0027] The application of the Ce-based metal-organic framework material Ce-DPA in the selective catalytic oxidation of indanone to prepare 1-indanone.

[0028] The Ce-based metal-organic framework material is used to catalytically oxidize indane to prepare 1-indanone under light irradiation, with the light wavelength selected from 390~520 nm.

[0029] The present invention will be further described below with reference to the embodiments. Example 1

[0030] H4ADIP (4 mg, 5 μmol) and Ce(NO3)3·6H2O (8 mg, 18 μmol) were dissolved in a solution containing 1.5 mL DMF, 0.5 mL CH3OH, and 0.5 mL H2O. The solution was sonicated until completely dissolved, then transferred to a high-pressure reactor lined with polytetrafluoroethylene (PTFE) and heated at 120 °C for 54 hours. After cooling to room temperature, the yellow powder was collected by centrifugation and filtered sequentially with DMF and ethanol, washing several times until the supernatant was clear and transparent with no dye adsorption residue. Finally, the yellow powder was vacuum dried overnight at 100 °C to obtain Ce-based metal-organic framework material Ce-DPA (e.g., ...). Figure 6 The X-ray diffraction of this material is as follows: Figure 1 The PXRD pattern, shown in the figure, is from a Rigaku Smart Lab X-ray diffractometer, demonstrating the successful synthesis of Ce-DPA. The X-ray photoelectron spectrum of Ce-DPA after illumination is shown below. Figure 2 As shown in the XPS Ce 3d, the X-ray photoelectron spectrum of Ce-DPA before illumination is as follows: Figure 2 As shown in the XPS Ce 3d, the experimental instrument used was a Thermo ESCALAB Xi+ X-ray photoelectron spectrometer. In Ce-DPA, after illumination, the excited state of DPA will generate Ce. 3+ Oxidized to Ce 4+ Therefore, in Figure 2 Ce appeared in4+ The signal peak. Example 2

[0031] A mixed solution of 3 mL acetonitrile and 0.5 mL dichloromethane was added to a 20 mL photocatalytic reaction tube, followed by Ce-DPA (5.0 μmol) and indane (0.1 mmol) prepared in Example 1. The tube was sealed with a stopper, and Ar gas was introduced to eliminate interference from other gases. The reaction was carried out under a 395 nm light source at 40 °C with continuous stirring for 8 hours. After the reaction was completed, the internal standard 1,3,5-trimethoxybenzene (0.1 mmol) was added. The Ce-DPA catalyst was removed by centrifugation, and the supernatant was concentrated by vacuum distillation. The yield was determined by gas chromatography. The yield curve of Ce-DPA catalyzing the oxidation of indane to 1-indanone under photocatalytic conditions as a function of time is shown below. Figure 4 As shown, the yield of 1-indanone increased linearly with time and stabilized within 10 h. Furthermore, the yield did not increase further after 8 hours of Ce-DPA removal, indicating that Ce-DPA is a true heterogeneous photocatalyst with a stable structure that did not collapse. Example 3

[0032] A mixed solution of 3 mL acetonitrile and 0.5 mL dichloromethane was added to a 20 mL photocatalytic reaction tube. Then, Ce-DPA (5.0 μmol) prepared in Example 1 and various aromatic hydrocarbons such as indane and ethylbenzene (0.1 mmol) were added. The tube was sealed with a stopper, and Ar gas was introduced to eliminate interference from other gases. The reaction was carried out under a 395 nm light source at 40 °C with continuous stirring for 8 hours. After the reaction was complete, the Ce-DPA precipitate was obtained by centrifugation and washed with dichloromethane until no product residue remained in the supernatant. The washed precipitate was vacuum dried to remove solvent molecules. The dried catalyst was then reintroduced into the reaction system of Example 2, and this process was repeated five times. The cyclic yield and selectivity of Ce-DPA catalyzing the oxidation of indane to 1-indanone were as follows: Figure 5 As shown, the selectivity for the product 1-indanone did not decrease over five cycles. Example 4

[0033] A mixed solution of 3 mL acetonitrile and 0.5 mL dichloromethane was added to a 20 mL photocatalytic reaction tube. Then, Ce-DPA (5.0 μmol) prepared in Example 1 and various aromatic hydrocarbons such as indene and ethylbenzene (0.1 mmol) were added. The tube was sealed with a stopper, and Ar gas was introduced to eliminate interference from other gases. The reaction was carried out under a 395 nm light source at 40 °C with continuous stirring for 8 hours. After the reaction was complete, the internal standard 1,3,5-trimethoxybenzene (0.1 mmol) was added, and the Ce-DPA catalyst was removed by centrifugation. The yield was determined by gas chromatography. Ce-DPA showed moderate yields and selectivity greater than 99% in catalyzing the oxidation of various aromatic hydrocarbons to their corresponding ketones under photocatalytic conditions, successfully expanding the substrate range, as shown in the table below.

[0034]

[0035] The Ce-based metal-organic framework material prepared by this method retains the high oxidation potential of excited-state DPA and can activate oxygen. Its excited-state DPA can oxidize Ce(III) to Ce(IV), thereby generating chlorine radicals through the LMCT process. It effectively avoids the aggregation and self-quenching of DPA, thus realizing the catalytic oxidation of various aromatic hydrocarbons to generate the corresponding ketones without the generation of by-products, and exhibits good stability in cyclic catalysis.

[0036] The above embodiments are only used to illustrate the present invention. Any equivalent transformations and improvements made on the basis of the technical solutions of the present invention should not be excluded from the protection scope of the present invention.

Claims

1. A method for preparing Ce-based metal-organic framework materials through the synergistic activation and transformation of CH bonds and oxygen, characterized in that, Includes the following steps: Ce-DPA, a metal-organic framework material, was prepared by coordination of Ce salt with organic linker H4ADIP via a solvothermal method. The structure of H4ADIP is as follows: ； The molar ratio of Ce salt to organic linker H4ADIP is 5~1:

1.

2. The preparation method according to claim 1, characterized in that, The Ce salt is cerium chloride or cerium nitrate.

3. The preparation method according to claim 1, characterized in that, The solvent used in the reaction is selected from N,N - Dimethylformamide, acetonitrile, N,N The reaction is carried out at least one of dimethylacetamides at a temperature of 80-120°C for 15-60 hours.

4. The preparation method according to claim 1, characterized in that, Ce salt and DPA are added to a solvent and sonicated until a suspension is formed. Then, the suspension is transferred to a high-pressure reactor and heated at 80-120°C for 15-60 hours. After centrifugation or filtration, washing, and vacuum drying, Ce-based metal-organic framework material Ce-DPA is obtained.

5. A method for the synergistic activation and transformation of Ce-based metal-organic frameworks by CH bonds and oxygen, characterized in that: It is prepared by the method described in any one of claims 1-4.

6. The application of the Ce-based metal-organic framework material according to claim 5, characterized in that: The Ce-based metal-organic framework material is used in the catalytic activation of indanone to prepare 1-indanone.

7. The application according to claim 6, characterized in that, The Ce-based metal-organic framework material is used to catalytically activate indane to prepare 1-indanone under light irradiation, with the light wavelength range being 390~520 nm.

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