Carbon-carbon double bond bridged heteroporous covalent organic framework materials, preparation and application

Abstract

The invention discloses a carbon-carbon double bond bridged heteroporous covalent organic framework material, preparation and application, and relates to the technical field of covalent organic framework materials. The preparation method includes: in an inert atmosphere glove box, 1,3,5-tris (2,6-dimethylpyridine-4-yl) benzene, phthalaldehyde derivatives, benzoic acid and benzoic anhydride are added to an ampoule; vacuum flame seals the ampoule in a liquid nitrogen bath by freezing vacuum pumping and supplementing an inert atmosphere, and transfers the ampoule to a muffle furnace for heating reaction; after the heating reaction is completed, it is naturally cooled to room temperature, the filter residue is collected, the filter residue is rinsed with different organic solvents respectively, and a mixed solvent Soxhlet extraction is performed, vacuum drying is performed, and finally a covalent organic framework material is obtained. The covalent organic framework material of the present invention has high chemical stability, high crystallinity, high specific surface area, and good thermal stability, which provides favorable conditions for the development and utilization of heteroporous covalent organic frameworks (COFs) in the field of catalysis.

Description

Technical Field

[0001] The present invention relates to the technical field of covalent organic framework materials, and specifically to a carbon-carbon double bond bridged heteroporous structure covalent organic framework material, a preparation method and application thereof, and in particular to a carbon-carbon double bond bridged heteroporous structure covalent organic framework material based on 1,3,5-tris(2,6-dimethylpyridin-4-yl)benzene, a preparation method and application thereof. Background Art

[0002] Covalent organic frameworks (COFs) are a type of porous material with long-range ordered structure and regular pore structure formed by organic small molecule monomers connected by covalent bonds in two-dimensional or three-dimensional space. Since the first two-dimensional COF based on boronate bond connection was reported in 2005 (Science, 2005, 310, 1166-1170), this type of material has shown broad application prospects in gas separation, heterogeneous catalysis, sensing, energy storage and conversion, and semiconductors due to its high specific surface area, regular pore structure, rich and designable structure and function. Generally speaking, the formation of crystalline COFs requires a self-healing process crystallization based on a reversible reaction to thermodynamically control the pre-formed amorphous framework. The dynamic covalent bonds that have been developed for COFs synthesis mainly include boronate bonds, imide bonds, acylhydrazone bonds, imide bonds, phenazine bonds, aromatic ether bonds, etc. This type of chemical bond has good reversibility, but there are still major deficiencies in stability, conjugation, and semiconductor activity. Among them, although the stability of the framework material is enhanced based on phenazine bonds and aromatic ether bonds, it is slightly insufficient in increasing the π-electron conjugation of the framework.

[0003] Based on this, in 2016, Zhang et al. reported a cyano-substituted carbon-carbon double bond bridged all-sp 2 Carbon-conjugated COFs (Polym.Chem.2016,7,4176-4181). Due to the introduction of stable carbon-carbon double bonds, this new type of COFs material exhibits ultra-high stability that is different from the past, and has the conjugated properties of the full carbon skeleton. In 2016, Zhao et al. reported a double-pore COFs bridged by an imine bond (Chem.Eur.J.2016,22,17784–17789), thus expanding the topological structure in the field of COFs. In 2017, Zhao et al. reported an imine-bridged three-pore COFs and realized the conversion between different pore sizes of COFs (J.Am.Chem.Soc.2017,139,6736-6743).

[0004] However, the synthesis of monomers required for all reported heteroporous covalent organic framework materials is relatively complex and all are connected by imine bonds, with poor chemical stability. Therefore, it is of great significance to find more simple and easily available core monomers to synthesize highly stable heteroporous covalent organic framework materials connected by carbon-carbon double bonds, expand their types, and enrich their functions.

[0005] Therefore, researchers in this field are committed to developing a covalent organic framework material with a heteroporous structure connected by carbon-carbon double bonds synthesized using a simple and readily available core monomer and a preparation method thereof. Summary of the invention

[0006] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is how to use easily available monomers without any additional modification to directly synthesize a heteroporous covalent organic framework material connected by carbon-carbon double bonds with high crystallinity, high specific surface area, high thermal stability and chemical stability, and to provide a universal synthesis and preparation method thereof.

[0007] To achieve the above object, the present invention provides a method for preparing a carbon-carbon double bond bridged heteroporous structure covalent organic framework material, comprising the following steps:

[0008] Step 1, in an inert atmosphere glove box, add 1,3,5-tris(2,6-dimethylpyridin-4-yl)benzene, a phthalaldehyde derivative, benzoic acid and benzoic anhydride into an ampoule;

[0009] Step 2, vacuum flame sealing the ampoule in a liquid nitrogen bath by freezing and vacuumizing and supplementing with an inert atmosphere, and transferring the ampoule to a muffle furnace for heating reaction;

[0010] Step 3: After the heating reaction is completed, the ampoule is cooled naturally to room temperature, the filter residue is collected, and the filter residue is washed with different organic solvents respectively, extracted with a mixed solvent Soxhlet, placed in a vacuum oven for vacuum drying, and finally the covalent organic framework material is obtained.

[0011] In a preferred embodiment of the present invention, the inert atmosphere is nitrogen.

[0012] In a preferred embodiment of the present invention, the phthalaldehyde derivative is selected from terephthalaldehyde or biphenyldicarboxaldehyde.

[0013] Furthermore, when the phthalaldehyde derivative is selected from terephthalaldehyde, the prepared covalent organic framework material is DP-COF-1; when the phthalaldehyde derivative is selected from biphenyldicarboxaldehyde, the prepared covalent organic framework material is DP-COF-2.

[0014] Further, when the phthalaldehyde derivative is selected from terephthalaldehyde, the amount of 1,3,5-tris(2,6-dimethylpyridine-4-yl)benzene is 78.71 mg, and the amount of terephthalaldehyde is 80.48 mg; when the phthalaldehyde derivative is selected from biphenyldicarboxaldehyde, the amount of 1,3,5-tris(2,6-dimethylpyridine-4-yl)benzene is 78.71 mg, and the amount of biphenyldicarboxaldehyde is 126.14 mg.

[0015] In another preferred embodiment of the present invention, the reaction temperature of the heating reaction in step 2 is 180°C, and the reaction time is 120 hours; the drying temperature of the vacuum drying in step 3 is 60°C, and the drying time is 12 hours.

[0016] The present invention also provides a carbon-carbon double bond bridged heteroporous structure covalent organic framework material, which is prepared by the preparation method as described above.

[0017] In a preferred embodiment of the present invention, the carbon-carbon double bond bridged heteroporous structure covalent organic framework material is DP-COF-1 or DP-COF-2.

[0018] In a preferred embodiment of the present invention, the specific surface areas of the DP-COF-1 and the DP-COF-2 are 551 m 2 g -1 and 939m 2 g -1 The pore size distributions of the DP-COF-1 and the DP-COF-2 are concentrated at 0.6nm-1.5nm and 0.6nm-2.0nm, respectively; the visible light absorption band edge wavelengths of the DP-COF-1 and the DP-COF-2 are 450nm and 460nm, respectively.

[0019] The present invention also provides an application of the carbon-carbon double bond bridged heteroporous structure covalent organic framework material as described above in catalyzing the bromination reaction of aromatic compounds in the presence of hydrobromic acid.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention prepares 1,3,5-tris(2,6-dimethylpyridin-4-yl)benzene for the first time and uses it as a core monomer to synthesize heteroporous covalent organic framework materials connected by carbon-carbon double bonds under the catalytic conditions of benzoic acid and benzoic anhydride, enriching the connection methods of heteroporous covalent organic frameworks and improving the chemical stability of heteroporous COFs.

[0022] The COFs material obtained by the invention has high crystallinity, high specific surface area, hexagonal pore structures of different shapes, good thermal stability and two-dimensional layered morphology.

[0023] The COFs prepared by the present invention have abundant pyridine sites and a two-dimensional layered morphology, which provides favorable conditions for the development and utilization of the heteroporous COFs in the field of catalysis.

[0024] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The synthesis and structural schematic diagram of two heteroporous organic frameworks with 1,3,5-tris(2,6-dimethylpyridin-4-yl)benzene as the core and carbon-carbon double bonds as the connection, where the two COFs are named DP-COF-1 and DP-COF-2;

[0026] Figure 2 The powder X-ray diffraction spectra and simulated X-ray diffraction spectra of the heteroporous covalent organic frameworks connected by two carbon-carbon double bonds in Example 1 and Example 2;

[0027] Figure 3 The nitrogen adsorption-desorption isotherm spectra and pore size distribution curves of the heteroporous covalent organic frameworks connected by two carbon-carbon double bonds in Example 1 and Example 2;

[0028] Figure 4 This is a scanning electron microscope photo of the heteroporous covalent organic framework connected by two carbon-carbon double bonds in Example 1 and Example 2;

[0029] Figure 5 Transmission electron microscope photos of two carbon-carbon double bonds connecting heteroporous covalent organic frameworks in Example 1 and Example 2;

[0030] Figure 6 The UV-visible diffuse reflectance spectra of the heteroporous covalent organic frameworks connected by two carbon-carbon double bonds in Example 1 and Example 2;

[0031] Figure 7 Thermogravimetric analysis spectra of two carbon-carbon double bonds connecting heteroporous covalent organic frameworks in Example 1 and Example 2 under nitrogen atmosphere;

[0032] Figure 8 The diagrams are other highly symmetrical monomer structures prepared by the method of the present invention and alternative structures of phthalaldehyde derivatives. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the embodiments are only for illustrating the present invention and are not intended to limit the scope of the invention in any form. The present invention can be embodied by many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0034] In the drawings, components with the same structure are indicated by the same numerical reference numerals, and components with similar structures or functions are indicated by similar numerical reference numerals. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, the thickness of the components is appropriately exaggerated in some places in the drawings.

[0035] Example 1

[0036] Preparation of carbon-carbon double bond bridged heteroporous covalent organic framework material DP-COF-1:

[0037] like Figure 1 As shown, in a glove box with an argon atmosphere, 78.71 mg of reaction monomer 1,3,5-tris(2,6-dimethylpyridine-4-yl)benzene, 80.48 mg of terephthalaldehyde, 7.32 mg of benzoic acid and 135.74 mg of benzoic anhydride are added to a round-bottom solvent ampoule with a volume of 5 mL; the ampoule is sealed with butane combustible gas, and the ampoule is transferred to a 180° C. constant temperature oven for reaction for 120 hours; after the heating reaction is completed, the ampoule is naturally cooled to room temperature, and the filter residue is collected by vacuum filtration, and the filter residue is washed with acetone, methanol and dichloromethane respectively, and then vacuum dried at 60° C. for 12 hours, and finally the conjugated heteroporous structure covalent organic framework DP-COF-1 connected by two carbon-carbon double bonds is obtained.

[0038] Example 2

[0039] Preparation of carbon-carbon double bond bridged heteroporous covalent organic framework material DP-COF-2:

[0040] like Figure 1As shown, in a glove box with an argon atmosphere, 78.71 mg of reaction monomer 1,3,5-tris(2,6-dimethylpyridine-4-yl)benzene, 126.14 mg of biphenyl dicarboxaldehyde, 7.32 mg of benzoic acid and 135.74 mg of benzoic anhydride are added to a round-bottom solvent ampoule with a volume of 5 mL; the ampoule is sealed with butane combustible gas, and the ampoule is transferred to a 180° C. constant temperature oven for reaction for 120 hours; after the heating reaction is completed, the ampoule is naturally cooled to room temperature, and the filter residue is collected by vacuum filtration, and the filter residue is washed with acetone, methanol and dichloromethane respectively, and then vacuum dried at 60° C. for 12 hours, and finally the conjugated heteroporous structure covalent organic framework DP-COF-2 connected by two carbon-carbon double bonds is obtained.

[0041] The covalent organic framework materials DP-COF-1 and DP-COF-1 prepared in Example 1 and Example 2 were characterized, and it was found that the organic framework material prepared by the present invention was synthesized using 1,3,5-tris(2,6-dimethylpyridin-4-yl)benzene as the core monomer. The covalent organic framework material has high crystallinity and a specific surface area of ​​up to 1019m 2 g -1 The covalent organic framework material has two different hexagonal channels and a fully conjugated skeleton structure. The highest visible light absorption is in the 460nm band. At the same time, the covalent organic framework material has high chemical stability and abundant pyridine sites. The covalent organic framework material can catalyze the bromination reaction of aromatic compounds in the presence of hydrobromic acid.

[0042] The crystal structure of the heteroporous covalent organic framework connected by two carbon-carbon double bonds in the present invention is determined by powder X-ray diffraction and analyzed by theoretical simulation.

[0043] The porous structure of the heteroporous covalent organic framework connected by two carbon-carbon double bonds in the present invention is characterized by nitrogen adsorption and desorption test: the characterization results obtained include nitrogen adsorption and desorption isotherms, BET specific surface area and pore size distribution. The results are as follows Figure 2-Figure 8 shown.

[0044] like Figure 2 As shown in the figure, the powder X-ray diffraction pattern of the obtained two-dimensional covalent organic framework connected by two carbon-carbon double bonds is consistent with the results of theoretical simulation. The results show that the prepared sample belongs to the hexagonal system and has good crystallinity.

[0045] like Figure 3 As shown, the scanning electron microscope image of the obtained two-dimensional covalent organic framework connected by two carbon-carbon double bonds is shown. The results show that the prepared two-dimensional covalent organic framework connected by two carbon-carbon double bonds has a uniform two-dimensional layered morphology.

[0046] like Figure 4 As shown, the transmission electron micrograph of the obtained two-dimensional covalent organic framework connected by two carbon-carbon double bonds. The results show that the prepared two-dimensional covalent organic framework connected by two carbon-carbon double bonds has a uniform layered morphology.

[0047] like Figure 5 As shown in the figure, the nitrogen adsorption isotherm and pore size distribution curve of the obtained two-dimensional covalent organic framework connected by two carbon-carbon double bonds. The results show that the prepared two-dimensional covalent organic framework connected by two carbon-carbon double bonds has a porous structure with a BET specific surface area of ​​551m 2 g -1 and 1019m 2 g -1 , the pore size distribution is concentrated at 0.6nm, 1.5nm, and 0.6nm, 2.0nm respectively.

[0048] like Figure 6 As shown, the UV-visible diffuse reflectance spectrum of the obtained two-dimensional covalent organic frameworks connected by two carbon-carbon double bonds. The results show that the absorption band edge wavelengths of the two prepared two-dimensional covalent organic frameworks connected by two carbon-carbon double bonds are 460nm and 450nm, respectively, covering part of the visible light band.

[0049] like Figure 7 The thermogravimetric curve of the obtained two-dimensional covalent organic framework material connected by two carbon-carbon double bonds is shown in Figure 1. The results show that the residual mass of the two prepared two-dimensional covalent organic framework materials connected by two carbon-carbon double bonds in a nitrogen atmosphere at 800°C is 68% and 70%, respectively, indicating that the prepared organic framework material has good thermal stability.

[0050] In addition, the key monomer of the 2,6-dimethylpyridine substituted derivative prepared in the present invention can also be a similar molecule with other structures, such as Figure 8 As shown in A; the phthalaldehyde derivatives may also be dialdehyde-substituted aromatic derivatives of other structures, such as Figure 8 As shown in B. According to the concept of the present invention, the specific preparation methods of these monomers are similar to those of Example 1 or Example 2 of the present invention, and no further explanation is given here.

[0051] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for preparing a carbon-carbon double bond bridged heteroporous structure covalent organic framework material, characterized in that: The steps include: Step 1, in an inert atmosphere glove box, add 1,3,5-tris(2,6-dimethylpyridin-4-yl)benzene, terephthalaldehyde or biphenyldicarboxaldehyde, benzoic acid and benzoic anhydride into an ampoule; Step 2, vacuum flame sealing the ampoule in a liquid nitrogen bath by freezing and vacuumizing and supplementing with an inert atmosphere, and transferring the ampoule to a muffle furnace for heating reaction; Step 3: After the heating reaction is completed, the ampoule is cooled naturally to room temperature, the filter residue is collected, and the filter residue is washed with different organic solvents respectively, extracted with a mixed solvent Soxhlet, placed in a vacuum oven for vacuum drying, and finally the covalent organic framework material is obtained.

2. The method for preparing the carbon-carbon double bond bridged heteroporous structure covalent organic framework material according to claim 1, characterized in that: The inert atmosphere is nitrogen.

3. The method for preparing the carbon-carbon double bond bridged heteroporous structure covalent organic framework material according to claim 1, characterized in that: When selected from terephthalaldehyde, the amount of 1,3,5-tris(2,6-dimethylpyridin-4-yl)benzene is 78.71 mg, and the amount of terephthalaldehyde is 80.48 mg; when selected from biphenyldicarboxaldehyde, the amount of 1,3,5-tris(2,6-dimethylpyridin-4-yl)benzene is 78.71 mg, and the amount of biphenyldicarboxaldehyde is 126.14 mg.

4. The method for preparing the carbon-carbon double bond bridged heteroporous covalent organic framework material according to claim 1, characterized in that: The reaction temperature of the heating reaction in step 2 is 180° C., and the reaction time is 120 hours; the drying temperature of the vacuum drying in step 3 is 60° C., and the drying time is 12 hours.

5. A carbon-carbon double bond bridged heteroporous covalent organic framework material, characterized in that: The preparation is obtained by the preparation method as claimed in claim 1.

6. The carbon-carbon double bond bridged heteroporous structure covalent organic framework material according to claim 5, characterized in that: When terephthalaldehyde is selected, the prepared covalent organic framework material is DP-COF-1; when biphenyldicarboxaldehyde is selected, the prepared covalent organic framework material is DP-COF-2; the specific surface areas of DP-COF-1 and DP-COF-2 are 551 m 2 / g and 939 m 2 / g; the pore size distributions of the DP-COF-1 and the DP-COF-2 are concentrated at 0.6 nm, 1.5 nm and 0.6 nm, 2.0 nm, respectively; the visible light absorption band edge wavelengths of the DP-COF-1 and the DP-COF-2 are 450 nm and 460 nm, respectively.

7. Use of the carbon-carbon double bond bridged heteroporous covalent organic framework material as claimed in claim 5 in catalyzing the bromination reaction of aromatic compounds in the presence of hydrobromic acid.

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