A pyridine / pyranyl-linked COFs and its preparation and application

Abstract

The present invention relates to the field of chemical synthesis technology, and in particular to a pyridine / pyranyl-linked COFs and its preparation and application. The present invention first dissolves a precursor in a solvent to obtain a precursor solution; then heats the precursor solution to undergo a polymerization reaction, and post-treats the precursor solution to obtain the desired product: pyridine-linked COFs or pyranyl-linked COFs. The present invention is the first to utilize an Aldol condensation reaction and a Michael addition cyclization tandem reaction in a one-pot method to prepare novel pyridine / pyranyl-linked COFs. In the field of covalent organic porous material research, it provides a COFs bonding mode and synthesis method that is easier to synthesize, more stable, and easier to modify.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and in particular to pyridine / pyranyl-linked COFs and preparation and application thereof. Background Art

[0002] Covalent organic frameworks (COFs) are novel porous materials composed of organic building blocks self-assembled through covalent bonds. They have attracted widespread attention due to their well-ordered structure, easily tunable frameworks, diverse covalent bonding methods, and permanent porosity. They have been widely used in fields such as adsorption and separation, catalysis, sensing, energy storage, optoelectronics, and biomedicine. To date, the most commonly used bonding mechanisms for constructing COFs are limited to BO, BN, Si-O, and C=N bonds. The self-healing properties of these reversible covalent bonds facilitate the design and synthesis of highly ordered structures. However, the poor chemical stability and weak electron delocalization of these bonds limit the practical application of COFs.

[0003] In the field of covalent organic frameworks (COFs), diverse bonding modes are crucial for creating robust structures with high crystallinity and diverse functionalities. To construct highly stable and electron-delocalized COFs, various novel bonding modes (oxazole / thiazole / C=C bond / pyrazine / dioxin / imidazole, etc.) have been used to prepare ultrastable COFs, expanding the application of COFs to organic electronics, supercapacitors, photocatalysis, lithium-ion battery cathodes, ferromagnetic materials, etc. However, the poor reversibility of conjugated bonds in the formation of COFs with novel bonding modes is not conducive to self-regulation to obtain highly crystalline materials. Furthermore, the limited number of novel bonding-type functional building blocks and the high cost have largely hindered the development of diversified bonding modes in COFs.

[0004] Therefore, it is crucial to use cheap and readily available organic building blocks to controllably synthesize functionalized highly stable COFs through a one-pot complex reaction. Summary of the Invention

[0005] In order to solve the above problems, the purpose of the present invention is to provide a pyridine / pyranyl-linked COFs and its preparation and application. The present invention first dissolves the precursor in a solvent to obtain a precursor solution; then heats the precursor solution and polymerizes it, and post-treats it to obtain the target product: pyridine-linked COFs or pyranyl-linked COFs. The present invention is the first to utilize an Aldol condensation reaction and a Michael addition cyclization tandem reaction in a one-pot method to prepare new pyridine / pyranyl-linked COFs. In the field of covalent organic porous material research, it provides a COFs bonding mode and synthesis method that is easier to synthesize, more stable, and easier to modify.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The first object of the present invention is to provide a pyridine / pyranyl-linked COFs, including pyridine-linked COFs (NCOF) and pyranyl-linked COFs (OCOF),

[0008] The pyridyl-linked COFs have a backbone structure as shown in formula (I), where the dotted structure in formula (I) represents that the dotted structure shown in formula (I) is specifically connected with the topological structure to extend infinitely;

[0009]

[0010] The pyranyl-linked COFs have a skeleton structure as shown in formula (II), where the dotted structure in formula (II) represents that the dotted structure shown in formula (II) is specifically connected with the topological structure to extend infinitely;

[0011]

[0012] A second object of the present invention is to provide a method for preparing pyridine / pyranyl-linked COFs, comprising the following steps:

[0013] (S1) dissolving a precursor in a solvent to obtain a precursor solution;

[0014] (S2) The precursor solution is heated to undergo polymerization (a tandem reaction of Aldol condensation and Michael addition cyclization), followed by post-treatment to obtain the desired product: pyridyl-linked COFs or pyranyl-linked COFs.

[0015] In one embodiment of the present invention, in step (S1), when the target product is pyridyl-linked COFs, the precursors are terephthalaldehyde, 4,4'-diacetylbiphenyl and ammonium acetate, and the solvent is a mixed solution of tert-butanol and 1,4-dioxane.

[0016] In one embodiment of the present invention, the molar ratio of terephthalaldehyde, 4,4'-diacetylbiphenyl and ammonium acetate is 7.5-15.0:14.9-29.8:44.7-89.5;

[0017] Preferably, the molar ratio of terephthalaldehyde, 4,4'-diacetylbiphenyl and ammonium acetate is 1:2:6-1:3:9;

[0018] The volume ratio of tert-butanol and 1,4-dioxane is 1:1.

[0019] In one embodiment of the present invention, when the target product is pyridyl-linked COFs, acetic acid is required as a catalyst.

[0020] In one embodiment of the present invention, in step (S1), when the target product is pyranyl-linked COFs, the precursors are terephthalaldehyde, 4,4'-diacetylbiphenyl and boron trifluoride etherate, and the solvent is a mixed solution of n-propanol and mesitylene.

[0021] In one embodiment of the present invention, the usage ratio of terephthalaldehyde, 4,4'-diacetylbiphenyl and boron trifluoride etherate is 29.8-37.2 mmol: 59.6-74.5 mmol: 16 -20 mL;

[0022] Preferably, the molar ratio of terephthalaldehyde, 4,4'-diacetylbiphenyl and boron trifluoride etherate is 1:2:4-1:3:6.

[0023] The volume ratio of n-propanol to mesitylene is 1:1.

[0024] In one embodiment of the present invention, in step (S2), when the target product is pyridyl-linked COFs, the polymerization reaction temperature is 110° C.-130° C. and the polymerization time is 70 h-80 h.

[0025] In one embodiment of the present invention, in step (S2), when the target product is pyranyl-linked COFs, the polymerization reaction temperature is 80° C.-100° C. and the polymerization time is 70 h-80 h.

[0026] In one embodiment of the present invention, in step (S2), the post-treatment is vacuum drying after washing.

[0027] In one embodiment of the present invention, when the target product is pyridyl-linked COFs, it is washed with N,N-dimethylformamide, water, and tetrahydrofuran in sequence, and then dried in a vacuum drying oven at 50° C.-80° C. for 12 h-24 h.

[0028] In one embodiment of the present invention, when the target product is pyranyl-linked COFs, it is washed with N,N-dimethylformamide, water, and tetrahydrofuran in sequence, and then dried in a vacuum drying oven at 50° C.-80° C. for 12 h-24 h.

[0029] The third object of the present invention is to provide a pyridine / pyranyl-linked COFs for use in the fields of photoelectrocatalysis and adsorption separation.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention is the first to utilize an Aldol condensation reaction and a Michael addition cyclization tandem reaction in a one-pot method to prepare pyridine / pyranyl-linked COFs; in the field of organic porous polymer material research, it provides a COFs bonding mode and synthesis method that is easier to prepare, has high crystallinity, and high stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the powder X-ray diffraction pattern of NCOF prepared in Example 1;

[0033] Figure 2 Comparative Fourier transform infrared spectra of the NCOF prepared in Example 1 and its raw materials;

[0034] Figure 3 This is the solid-state NMR spectrum of NCOF prepared in Example 1;

[0035] Figure 4 This is the powder X-ray diffraction pattern of the OCOF prepared in Example 2;

[0036] Figure 5 Comparative Fourier transform infrared spectra of the OCOF prepared in Example 2 and its raw materials;

[0037] Figure 6 This is the solid-state NMR spectrum of OCOF prepared in Example 2. DETAILED DESCRIPTION

[0038] The present invention provides a pyridine / pyranyl-linked COFs, including pyridine-linked COFs and pyranyl-linked COFs.

[0039] The pyridyl-linked COFs have a backbone structure as shown in formula (I), where the dotted structure in formula (I) represents that the dotted structure shown in formula (I) is specifically connected with the topological structure to extend infinitely;

[0040]

[0041] The pyranyl-linked COFs have a skeleton structure as shown in formula (II), where the dotted structure in formula (II) represents that the dotted structure shown in formula (II) is specifically connected with the topological structure to extend infinitely;

[0042]

[0043] The present invention provides a method for preparing pyridine / pyranyl-linked COFs, comprising the following steps:

[0044] (S1) dissolving a precursor in a solvent to obtain a precursor solution;

[0045] (S2) The precursor solution is heated to undergo polymerization reaction, and then post-treated to obtain the target product: pyridyl-linked COFs or pyranyl-linked COFs.

[0046] In one embodiment of the present invention, in step (S1), when the target product is pyridyl-linked COFs, the precursors are terephthalaldehyde, 4,4'-diacetylbiphenyl and ammonium acetate, and the solvent is a mixed solution of tert-butanol and 1,4-dioxane.

[0047] In one embodiment of the present invention, the molar ratio of terephthalaldehyde, 4,4'-diacetylbiphenyl and ammonium acetate is 7.5-15.0:14.9-29.8:44.7-89.5;

[0048] Preferably, the molar ratio of terephthalaldehyde, 4,4'-diacetylbiphenyl and ammonium acetate is 1:2:6-1:3:9;

[0049] The volume ratio of tert-butanol and 1,4-dioxane is 1:1.

[0050] In one embodiment of the present invention, when the target product is pyridyl-linked COFs, acetic acid is required as a catalyst.

[0051] In one embodiment of the present invention, in step (S1), when the target product is pyranyl-linked COFs, the precursors are terephthalaldehyde, 4,4'-diacetylbiphenyl and boron trifluoride etherate, and the solvent is a mixed solution of n-propanol and mesitylene.

[0052] In one embodiment of the present invention, the usage ratio of terephthalaldehyde, 4,4'-diacetylbiphenyl and boron trifluoride etherate is 29.8-37.2 mmol: 59.6-74.5 mmol: 16 -20 mL;

[0053] Preferably, the molar ratio of terephthalaldehyde, 4,4'-diacetylbiphenyl and boron trifluoride etherate is 1:2:4-1:3:6.

[0054] The volume ratio of n-propanol to mesitylene is 1:1.

[0055] In one embodiment of the present invention, in step (S2), when the target product is pyridyl-linked COFs, the polymerization reaction temperature is 110° C.-130° C. and the polymerization time is 70 h-80 h.

[0056] In one embodiment of the present invention, in step (S2), when the target product is pyranyl-linked COFs, the polymerization reaction temperature is 80° C.-100° C. and the polymerization time is 70 h-80 h.

[0057] In one embodiment of the present invention, in step (S2), the post-treatment is vacuum drying after washing.

[0058] In one embodiment of the present invention, when the target product is pyridyl-linked COFs, it is washed with N,N-dimethylformamide, water, and tetrahydrofuran in sequence, and then dried in a vacuum drying oven at 50° C.-80° C. for 12 h-24 h.

[0059] In one embodiment of the present invention, when the target product is pyranyl-linked COFs, it is washed with N,N-dimethylformamide, water, and tetrahydrofuran in sequence, and then dried in a vacuum drying oven at 50° C.-80° C. for 12 h-24 h.

[0060] The present invention provides applications of pyridine / pyranyl-linked COFs in the fields of photoelectrocatalysis and adsorption separation.

[0061] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0062] In the following examples, unless otherwise specified, all reagents used are commercially available reagents, and all detection means and methods used are conventional detection means and methods in the art.

[0063] Example 1

[0064] This embodiment provides a pyridyl-linked COFs and a preparation method thereof.

[0065] Terephthalaldehyde (1 g, 7.5 mmol), 4,4'-diacetylbiphenyl (3.6 g, 7.5 mmol), and ammonium acetate (3.4 g, 44.7 mmol) were added to a Schlenk flask. A mixed solvent of tert-butyl alcohol (50 mL) and 1,4-dioxane (50 mL) was then added. Acetic acid solution (9 M, 20 mL) was then added as a catalyst and ultrasonically dispersed. The Schlenk flask was then placed in liquid nitrogen and frozen under vacuum. This process was repeated three times and then allowed to react in a 120°C oven for 72 hours. The resulting yellow powder was washed sequentially with N,N-dimethylformamide, water, and tetrahydrofuran, and then dried in a 50°C vacuum oven for 12 hours to obtain NCOF.

[0066] The powder X-ray diffraction spectrum of the above NCOF is as follows: Figure 1 As shown in the figure, it can be seen that the crystal diffraction peaks of the obtained material are distributed in 2θ=2~35°, and the peak intensity is relatively strong, indicating that the material is a crystalline material with uniform distribution of pore size and crystal plane distance.

[0067] Comparison of the Fourier transform infrared spectra of the above NCOF and synthetic raw materials Figure 2 As shown: the raw materials are terephthalaldehyde and 4,4'-diacetylbiphenyl with a small amount of residue. In the infrared spectrum of NCOF, pyridine (C=N) is at 1657cm-1 There are obvious stretching vibration peaks.

[0068] The solid carbon spectrum of the above NCOF is as follows Figure 3 shown.

[0069] After the above-mentioned test, the NCOF synthesized by the obtained product has a skeleton structure as shown in formula (I), and the dotted structure in formula (I) represents that it continues to be specifically connected with the dotted structure shown in formula (I) in a topological structure to extend infinitely;

[0070]

[0071] The NCOF prepared in this example can be further applied in the fields of photoelectrocatalysis and adsorption separation.

[0072] Example 2

[0073] This embodiment provides a pyranyl-linked COFs and a preparation method thereof.

[0074] Terephthalaldehyde (4 g, 29.8 mmol), 4,4'-diacetylbiphenyl (14.2 g, 59.6 mmol), and boron trifluoride etherate (16 mL) were added to a Schlenk flask. A mixed solvent of n-propanol (120 mL) and mesitylene (120 mL) was added. After ultrasonic dispersion, the Schlenk flask was placed in liquid nitrogen and frozen and vacuumed three times. After that, the reaction was continued in an 80°C oven for 72 hours. After the reaction, the resulting yellow powder was washed sequentially with N,N-dimethylformamide, water, and tetrahydrofuran, and then dried in a 50°C vacuum oven for 12 hours to obtain OCOF.

[0075] The powder X-ray diffraction spectrum of the above OCOF is as follows: Figure 4 As shown in the figure, it can be seen that the crystal diffraction peaks of the obtained material are distributed in 2θ=2~35°, and the peak intensity is relatively strong, indicating that the material is a crystalline material with uniform distribution of pore size and crystal plane distance.

[0076] Comparison of the Fourier transform infrared spectra of the above OCOF and synthetic raw materials Figure 5 As shown: the raw material is terephthalaldehyde, and there is a small amount of 4,4'-diacetylbiphenyl remaining. In the infrared spectrum of OCOF, pyran (C=O) is at 1658cm -1 There are obvious stretching vibration peaks. The solid carbon spectrum of the above OCOF is as follows Figure 6 shown.

[0077] After the above-mentioned test, the synthesized OCOF obtained by the product has a skeleton structure as shown in formula (II), and the dotted structure in formula (II) represents that it continues to be specifically connected with the dotted structure shown in formula (II) in a topological structure to extend infinitely;

[0078]

[0079] The OCOF prepared in this example can be further applied in the fields of photoelectrocatalysis and adsorption separation.

[0080] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the explanations of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing pyranyl-linked COFs, characterized in that: The following steps are involved: (S1) dissolving a precursor in a solvent to obtain a precursor solution; (S2) The precursor solution is heated to undergo polymerization reaction, and post-processing is performed to obtain the target product: pyranyl-linked COFs; In step (S1), the precursors are terephthalaldehyde, 4,4'-diacetylbiphenyl and boron trifluoride etherate, and the solvent is a mixed solution of n-propanol and mesitylene; The dosage ratio of terephthalaldehyde, 4,4'-diacetylbiphenyl and boron trifluoride ether is 29.8-37.2 mmol: 59.6-74.5 mmol: 16-20 mL; the volume ratio of n-propanol and mesitylene is 1:

1.

2. The method for preparing pyranyl-linked COFs according to claim 1, wherein: In step (S2), during the polymerization reaction, the temperature is 80°C-100°C and the time is 70h-80h.

3. The method for preparing pyranyl-linked COFs according to claim 1, wherein: In step (S2), the post-treatment is vacuum drying after washing.

4. Application of pyranyl-linked COFs in the field of photoelectrocatalysis and adsorption separation, characterized in that: The pyranyl-linked COFs are pyranyl-linked COFs prepared by the method according to any one of claims 1 to 3.

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