A method of synthesizing a trivalent rhodium covalent organic framework catalyst
By preparing trivalent rhodium covalent organic framework catalysts, the problems of Rh(III) catalyst recovery and insufficient stability of COF catalysts were solved, realizing efficient and multifunctional C(sp2)-H bond functionalization reactions with excellent stability and recyclability.
Patent Information
- Application Number
- CN202411468115.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-21
- Publication Date
- 2025-12-09
- Estimated Expiration
- 2044-10-21
AI Technical Summary
Existing Rh(III) catalysts have heavy metal residues in homogeneous reactions that are difficult to recover, their catalytic activity depends on complex and costly ligands, and the C=N bond of COF catalysts is unstable in strong acid environments. Most COF catalysts have a single reaction type and lack universality and tolerance.
A trivalent rhodium covalent organic framework catalyst was prepared by Schiff base condensation of 1,3,6,8-tetra-(p-aminophenyl)-pyrene with 2,2'-bipyridine-5,5'-dicarboxaldehyde, followed by oxidative cyclization and metallization with [Cp*RhCl2]2. This catalyst possesses an extended π-conjugated system and atomically dispersed trivalent rhodium active centers.
It achieves efficient recycling of trivalent rhodium catalysts, catalyzes regioselective C(sp2)-H bond functionalization reactions, and has excellent stability and multifunctionality, suitable for thermally driven or visible light driven reactions.
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Abstract
Description
TECHNICAL FIELD
[0001] The present disclosure relates to the technical field of organic functional material synthesis, and particularly relates to a synthesis method of a trivalent rhodium covalent organic framework catalyst. BACKGROUND
[0002] Over the past few decades, Rh(III)-catalyzed C(sp 2 )-H bond functionalization has made remarkable progress in the field of organic synthetic chemistry. This reaction can efficiently construct complex organic molecules, while having excellent atom economy and step economy (J.C. Lewis, R.G. Bergman and J.A. Ellman, Acc. Chem. Res., 2008, 41, 1013-1025). However, the use of Rh(III) catalysts under homogeneous reaction conditions usually leads to heavy metal residues, and these catalysts are difficult to recover by simple post-treatment (J.B. Zimmerman, P.T. Anastas, H.C. Erythropel and W. Leitner, Science, 2020, 367, 397-400). In addition, the catalytic activity of Rh(III) catalysts is highly dependent on the coordination ligand, but the synthesis of these ligands is usually complex and costly (B. Ye and N. Cramer, Acc. Chem. Res., 2015, 48, 1308-1318).
[0003] Covalent organic frameworks (COFs) have emerged as a new class of porous organic polymers with high crystallinity, periodic structure, tunability, and excellent stability (C. S. Diercks and O. M. Yaghi, Science, 2017, 355, eaal1585). Up to now, COFs have been widely applied in various chemical-related fields, especially in heterogeneous catalysis of organic transformations (J. Wang and S. Zhuang, Coord. Chem. Rev., 2019, 400, 213046). According to their working modes, the main roles of COFs in heterogeneous catalysis of organic transformations can be classified into the following types: (1) utilizing the acidity or basicity of preinstalled functional groups, COFs can act as heterogeneous Lewis acid or Lewis base catalysts to catalyze reactions (Q. Fang, S. Gu, J. Zheng, Z. Zhuang, S. Qiu and Y. Yan, Angew. Chem. Int. Ed., 2014, 53, 2878-2882); (2) through physical or chemical interactions, COFs can act as heterogeneous supports to highly disperse metal or other catalytic sites in the reaction system (S.-Y. Ding, J. Gao, Q. Wang, Y. Zhang, W.-G. Song, C.-Y. Su and W. Wang, J. Am. Chem. Soc., 2011, 133, 19816-19822), and then catalyze reactions; (3) utilizing the extended π-conjugated system to absorb visible light, COFs can drive reactions through energy transfer (ET) or single electron transfer (SET) (H. Wang, H. Wang, Z. Wang, L. Tang, G. Zeng, P. Xu, M. Chen, T. Xiong, C. Zhou, X. Li, D. Huang, Y. Zhu, Z. Wang and J. Tang, Chem. Soc. Rev., 2020, 49, 4135-4165); (4) by introducing chiral organic units, COFs can form asymmetric catalytically active sites to drive stereoselective reactions (X. Wang, X. Han, J. Zhang, X. Wu, Y. Liu and Y. Cui, J. Am. Chem. Soc., 2016, 138, 12332-12335). These modes of action demonstrate four different application strategies of COFs in heterogeneous catalysis of organic reactions. Based on these strategies, the participation of COFs can enable various organic transformations that are usually carried out under homogeneous conditions to be achieved under heterogeneous conditions, and the reaction efficiency can be maintained. More importantly, COFs are almost insoluble in any organic solvent and can be easily separated by simple filtration or centrifugation to achieve excellent recyclability and reaction sustainability.
[0004] In summary, the application of COF catalysts in organic transformations is likely to be the most ideal path to achieve green chemistry. However, COF catalysts still face the following challenges in practical applications. First, imine-linked COFs are often used to catalyze organic transformations, but the stability of the C=N bond is poor in a strong acid environment, which is difficult to meet the actual demand. Second, for metal covalent organic frameworks (MCOF), the main method to fix the metal center is through the coordination of the metal with the organic monomer. Although replacing the coordination bond with a covalent bond can significantly enhance the stability of the material, in some reactions that rely on precise coordination, such as transition metal-catalyzed selective C-H bond functionalization, the excessive stability may limit the tunability of the catalytic center, affect the effective interaction with the substrate, and thus reduce the reaction efficiency. In addition, in existing studies, most COF catalysts are only used for a single type of reaction, and their universality and resistance in different types of reactions have not been fully explored.
[0005] Therefore, the development of a trivalent rhodium covalent organic framework catalyst with excellent thermal stability, chemical stability and multifunctionality can realize the sustainable thermal-driven or visible light-driven Rh(III) catalyzed C(sp 2 )-H bond functionalization, which is of great significance to promote the development of materials chemistry and organic synthesis chemistry. SUMMARY
[0006] The application discloses a synthesis method of a trivalent rhodium covalent organic framework (RhCOF-SYNU-1), so as to obtain a covalent organic framework with an extended pi-conjugated system, excellent stability and an atomically dispersed trivalent rhodium active center.
[0007] The application is realized through the following technical scheme:
[0008] The application discloses a synthesis method of a trivalent rhodium covalent organic framework catalyst, which comprises the following steps:
[0009] The Schiff base condensation reaction is performed on 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 2,2'-bipyridine-5,5'-diformaldehyde;
[0010] The product obtained through the Schiff base condensation reaction is subjected to an oxidative cyclization reaction with p-trifluoromethyl phenylacetylene;
[0011] The product obtained through the oxidative cyclization reaction is subjected to metallization with [Cp*RhCl2]2, and finally the trivalent rhodium covalent organic framework catalyst is obtained;
[0012]
[0013] In the formula, R is a p-trifluoromethyl phenyl group.
[0014] Preferably, the trivalent rhodium covalent organic framework catalyst is prepared through the following steps:
[0015] Step 1: In a 10 mL ampoule, 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 2,2'-bipyridine-5,5'-dicarboxaldehyde were mixed uniformly in an organic solvent; the mixture in the ampoule was ultrasonically treated, and then acetic acid was added; the reaction was catalyzed by acetic acid, and the reaction mixture was degassed; the ampoule was sealed and placed in a 120°C oven for 72 hours; the solid obtained by the reaction was washed with tetrahydrofuran and acetone respectively, and then vacuum dried at 80°C to obtain orange powder Bpy-COF;
[0016] Step 2: In a 25 mL Schlenk tube, Bpy-COF, tetrachlorobenzoquinone, p-trifluoromethyl phenylacetylene, boron trifluoride ether and toluene were added; the Schlenk tube was sealed and reacted in an argon environment; after the reaction was completed, saturated NaHCO3 solution was added to quench the reaction, and the solid residue was separated by filtration and washed with N,N-dimethylformamide, water and methanol respectively; the obtained solid was vacuum dried at 80°C to obtain brown powder Q-COF;
[0017] Step 3: In a 25 mL Schlenk tube, Q-COF, [Cp*RhCl2]2 and methanol were added; the Schlenk tube was sealed and reacted in an argon environment; after the reaction was completed, the precipitate was separated by filtration and washed with methanol and dichloromethane respectively, and then the obtained solid was vacuum dried at 60°C to obtain deep red powder RhCOF-SYNU-1.
[0018] Preferably, the molar ratio of 1,3,6,8-tetra-(p-aminophenyl)-pyrene to 2,2'-bipyridine-5,5'-dicarboxaldehyde is 1:(0.5-2).
[0019] Preferably, the organic solvent in step 1 is 1,4-dioxane and mesitylene, and the volume ratio is 1:(0.5-1).
[0020] Preferably, the amount of acetic acid used in step 1 is 3-10 times the molar amount of 2,2'-bipyridine-5,5'-dicarboxaldehyde.
[0021] Preferably, the molar ratio of the theoretical imine bond of Bpy-COF to p-trifluoromethyl phenylacetylene, tetrachlorobenzoquinone and boron trifluoride ether is 1:(1-1.5):1.2:(0.5-1).
[0022] Preferably, the molar ratio of the theoretical bipyridine of Q-COF to [Cp*RhCl2]2 is 1:(0.5-1).
[0023] Preferably, the reaction temperature involved in steps 1-3 is 70-120°C.
[0024] Compared with the prior art, the present application has the following advantages:
[0025] The method is based on reasonable molecular design, and a covalent organic framework with an extended pi-conjugated system, excellent stability and an atomic-level dispersed trivalent rhodium active center is successfully prepared through acetic acid catalyzed Schiff base condensation reaction, oxidative cyclization reaction and trivalent rhodium metallization process of organic small molecule monomers in sequence. The covalent organic framework can be applied to the trivalent rhodium catalyzed region-selective C(sp 2 )-H bond functionalization reaction driven by heat or light, so that the trivalent rhodium is used in the region-selective C(sp 2 )-H bond functionalization with efficient recycling.
[0026] The synthesized trivalent rhodium covalent organic framework catalyst has high crystallinity and good stability, has an extended pi-conjugated system and an atomic-level dispersed trivalent rhodium active center, and can be used for catalyzing the region-selective C(sp 2 )-H bond functionalization reaction, so that the trivalent rhodium can be recycled and reused quickly.
[0027] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the disclosure of the present application. BRIEF DESCRIPTION OF DRAWINGS
[0028] The drawings incorporated into the specification and forming a part thereof show embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application.
[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.
[0030] Figure 1 The powder X-ray (PXRD) pattern of RhCOF-SYNU-1 synthesized in the present application;
[0031] Figure 2 The Fourier infrared spectrum (FT-IR) pattern of RhCOF-SYNU-1 synthesized in the present application;
[0032] Figure 3 The thermogravimetric analysis (TGA) curve of RhCOF-SYNU-1 synthesized in the present application;
[0033] Figure 4 The solid-state nuclear magnetic resonance spectrum (ssNMR) pattern of RhCOF-SYNU-1 synthesized in the present application;
[0034] Figure 5 Scanning transmission electron microscopy (STEM) image of RhCOF-SYNU-1 synthesized in the present application;
[0035] Figure 6 Ultraviolet-visible diffuse reflectance spectrum (UV-Vis) of RhCOF-SYNU-1 synthesized in the present application. DETAILED DESCRIPTION
[0036] The exemplary embodiments will be described in detail herein with reference to the attached drawings. The following description is made with reference to the accompanying drawings in which like reference numerals refer to like elements throughout the several views. The following description of exemplary embodiments is not representative of all possible embodiments consistent with the present application. Rather, they are merely examples of methodologies consistent with some aspects of the present application as detailed in the appended claims.
[0037] Example 1: Preparation of trivalent rhodium covalent organic framework catalyst
[0038] The preparation method of trivalent rhodium covalent organic framework catalyst is as follows:
[0039] (1) A 10 mL glass ampoule was charged with 1,3,6,8-tetra-(p-aminophenyl)-pyrene (85 mg, 0.15 mmol) and 2,2'-bipyridine-5,5'-diformyl (64 mg, 0.3 mmol) mixed uniformly in organic solvents 1,4-dioxane (1.5 mL) and mesitylene (1.5 mL). After the mixture in the ampoule was ultrasonically treated for 30 minutes, 0.5 mL of 3M aqueous acetic acid was added, and the reaction mixture was degassed. After the ampoule was sealed, it was placed in a 120°C oven for 72 hours. After the reaction was completed, the precipitate was separated by filtration and washed with tetrahydrofuran (3 x 20 mL) and acetone (3 x 20 mL). The resulting powder was dried under vacuum at 80°C for 12 h to obtain an orange powder Bpy-COF (135 mg).
[0040] (2) In a 25 mL Schlenk tube, add 24 mg of Bpy-COF and 0.05 mmol (12 mg) of tetrachlorobenzoquinone prepared in step (1), followed by 0.12 mmol (20 mg) of p-trifluoromethylphenylacetylene, 0.1 mmol (14 mg) of boron trifluoride ether, and 5 mL of toluene. Seal the Schlenk tube and react at 110 °C for 72 h in an argon atmosphere. After cooling to room temperature, quench the reaction with saturated NaHCO3. Filter to separate the solid residue and wash with N,N-dimethylformamide (3 × 10 mL), water (3 × 10 mL), and methanol (3 × 10 mL), respectively. Then, dry the resulting solid under vacuum at 80 °C for 12 h to obtain a brown powder Q-COF (39 mg).
[0041] (3) Add the Q-COF (41 mg) prepared in step (2) and [Cp*RhCl2]2 (0.2 mmol, 12 mg) to a 25 mL Schlenk tube, followed by methanol (5 mL). The mixture was stirred at 70 °C for 24 h under argon atmosphere. After the reaction was complete, the precipitate was separated by filtration and washed with methanol (3 × 10 mL) and dichloromethane (3 × 10 mL), respectively. The resulting solid was then dried under vacuum at 60 °C for 12 h to obtain a dark red powder RhCOF-SYNU-1 (43 mg).
[0042] Example 2: Structural characterization of the covalent organic framework material RhCOF-SYNU-1
[0043] 1. PXRD spectrum
[0044] like Figure 1 The powder X-ray diffraction (PXRD) patterns of the covalent organic framework material RhCOF-SYNU-1 were obtained using a powder X-ray diffractometer (Cu Kα radiation source, Ultima IV, Rigaku, Japan). The scanning range was 1.5° to 40°, and the scanning speed was 4° / min. The sharp diffraction peaks at 3.16°, 4.58°, 6.38°, 9.74°, 12.98°, and 23.86° were assigned to the (110), (020), (220), (330), (440), and (001) crystal planes, respectively. These PXRD results indicate that this covalent organic framework possesses high crystallinity.
[0045] 2. FT-IR spectrum
[0046] like Figure 2The Fourier transform infrared (FT-IR) spectrum of the covalent organic framework material RhCOF-SYNU-1 was collected on a Fourier transform infrared spectrometer (Bruker IFS). The spectrum was scanned in the range of 4000 cm -1 - 400 cm -1 -1 at 1524 cm -1 -1, while the stretching vibration peak of -CF3 appeared at 1325 cm -1 -1. The above spectrum results confirmed the successful synthesis of the covalent organic framework.
[0047] 3. TGA spectrum
[0048] As Figure 3 The thermogravimetric analysis (TGA) spectrum of the covalent organic framework material RhCOF-SYNU-1 was collected on a thermogravimetric analyzer (STA449 F5 / QMS 403D). The spectrum was scanned in the range of 30℃-800℃ at a scanning rate of 10℃ / min. The spectrum showed that the thermal decomposition temperature of the material was higher than 350℃, which proved that the covalent organic framework had excellent thermal stability.
[0049] 4. 13 C CP / MAS NMR spectrum
[0050] As Figure 4 The solid-state 13 C CP / MAS NMR) spectrum of the covalent organic framework RhCOF-SYNU-1 was collected on a solid-state NMR spectrometer (Bruker Avance III 400MHz). The spectrum showed that the carbon signal attributed to C=N clearly disappeared at δ = 156.9 ppm, which proved the successful conversion of the imine bond. Two signals produced in RhCOF-SYNU-1 at δ = 98.1 ppm and δ = 9.2 ppm were attributed to C directly connected to Rh and methyl C on the Cp* ring, respectively. The above results showed the successful synthesis of the covalent organic framework and the successful loading of Rh(III).
[0051] 5. STEM image
[0052] As Figure 5 The scanning transmission electron microscope (STEM) image of the covalent organic framework RhCOF-SYNU-1 was a scanning transmission electron microscope (STEM) image captured on a microscope (JEOL 2100FCS) at an acceleration voltage of 200kV. In the image, the trivalent rhodium active center can be clearly observed to be uniformly dispersed in the covalent organic framework at the atomic scale.
[0053] 6. UV-Vis spectra
[0054] As Figure 6 The UV-Vis diffuse reflectance spectrum of the covalent organic framework RhCOF-SYNU-1 was obtained using a Hitachi (UH4150) spectrophotometer. The scan range was 200-800 nm and the scan speed was v = 200 nm / min. The spectrum shows that the material has a high absorbance in the visible region of the spectrum between 400-600 nm.
[0055] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.
[0056] It is to be understood that the application is not limited to the embodiments described above, and various modifications and changes can be made without departing from the scope of the present application. The scope of the application is limited only by the claims that follow.
Claims
1. A method for synthesizing a trivalent rhodium covalent organic framework catalyst, characterized in that, include: Schiff base condensation reaction was carried out via 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 2,2'-bipyridine-5,5'-dicarboxaldehyde; The product obtained from the Schiff base condensation reaction was subjected to an oxidative cyclization reaction with p-trifluoromethylphenylacetylene. The product obtained from the oxidative cyclization reaction is then metallized with [Cp*RhCl2]2 to finally obtain a trivalent rhodium covalent organic framework catalyst; ， Wherein, R is p-trifluoromethylphenyl.
2. The method for synthesizing a trivalent rhodium covalent organic framework catalyst according to claim 1, characterized in that, It is prepared through the following steps: Step 1: In a 10 mL ampoule, 1,3,6,8-tetra-(p-aminophenyl)-pyrene (Formula I) and 2,2'-bipyridine-5,5'-dicarboxaldehyde (Formula II) were mixed evenly in an organic solvent; the mixture in the ampoule was then sonicated and acetic acid was added; the reaction was carried out under the catalysis of acetic acid, and the reaction mixture was degassed; after sealing the ampoule, it was allowed to stand in an oven at 120°C for 72 hours; the solid obtained from the reaction was washed with tetrahydrofuran and acetone, and then dried under vacuum at 80°C to obtain an orange powder, Bpy-COF. Step 2: Add Bpy-COF, tetrachlorobenzoquinone, p-trifluoromethylphenylacetylene, boron trifluoride diethyl ether, and toluene to a 25 mL Schlenk tube; seal the Schlenk tube and react in an argon atmosphere. After the reaction is complete, quench the reaction with saturated NaHCO3 solution, filter to separate the solid residue, and then use... N , N The solid was washed with dimethylformamide, water, and methanol; the resulting solid was then vacuum dried at 80°C to obtain a brown powder, Q-COF. Step 3: Add Q-COF, [Cp*RhCl2]2 and methanol to a 25 mL Schlenk tube; seal the Schlenk tube and react in an argon atmosphere. After the reaction is complete, filter to separate the precipitate, and wash with methanol and dichloromethane respectively. Then dry the obtained solid under vacuum at 60 °C to obtain a dark red powder RhCOF-SYNU-1.
3. The method for synthesizing a trivalent rhodium covalent organic framework catalyst according to claim 2, characterized in that: The molar ratio of 1,3,6,8-tetra-(p-aminophenyl)-pyrene to 2,2'-bipyridine-5,5'-dicarboxaldehyde is 1:(0.5~2).
4. The method for synthesizing a trivalent rhodium covalent organic framework catalyst according to claim 2, characterized in that: The organic solvent mentioned in step 1 is 1,4-dioxane and mesitylene, with a volume ratio of 1:(0.5~1).
5. The method for synthesizing a trivalent rhodium covalent organic framework catalyst according to claim 2, characterized in that: The amount of acetic acid used in step 1 is 3 to 10 times the molar amount of 2,2'-bipyridine-5,5'-dicarboxaldehyde.
6. The method for synthesizing a trivalent rhodium covalent organic framework catalyst according to claim 2, characterized in that: The theoretical imine bond of Bpy-COF has a molar ratio of 1 : (1~1.5) : 1.2 : (0.5~1) to p-trifluoromethylphenylacetylene, tetrachlorobenzoquinone, and boron trifluoride ether.
7. The method for synthesizing a trivalent rhodium covalent organic framework catalyst according to claim 2, characterized in that: The theoretical molar ratio of bipyridine to [Cp*RhCl2]2 in Q-COF is 1:(0.5~1).
8. The method for synthesizing a trivalent rhodium covalent organic framework catalyst according to claim 2, characterized in that: The reaction temperature involved in steps 1-3 is 70~120℃.