Three-dimensional molecular motor covalent organic framework material and preparation method thereof

Abstract

The invention is applicable to the technical field of covalent organic framework materials, and provides a three-dimensional molecular motor covalent organic framework material and a preparation method thereof, and the preparation method comprises the following steps: carrying out a dehydration condensation reaction on an aldehyde group monomer and an amino monomer in the presence of a catalyst and a solvent to obtain a crude product; washing, filtering and drying the crude product to obtain a three-dimensional molecular motor covalent organic framework material; wherein the aldehyde group monomer is 4, 4 '-(9-(2-methyl-2, 3-dihydro-1H-cyclopenta [a] naphthalene-1-yl-alkene)-9H-fluorene-2, 7-diyl) dibenzaldehyde, and the aldehyde group monomer is 4, 4'-(9-(2-methyl-2, 3-dihydro-1H-cyclopenta [a] naphthalene-1-yl) alkene. The amino monomer is tetra (2-fluoro-4-aminobiphenyl) methane. The embodiment of the invention realizes an example of embedding the molecular motor into a three-dimensional COF skeleton, and has clear crystallinity and a repeatable synthesis route.

Description

Technical Field

[0001] The present invention belongs to the technical field of covalent organic framework materials, and particularly relates to a three-dimensional molecular motor covalent organic framework material and a preparation method thereof. Background Art

[0002] Inspired by natural systems, significant progress has been made in the field of synthetic molecular machines, which can precisely control molecular motion through external stimuli. Different from biomolecular machines, artificial molecular machines need to be integrated into nanostructured macroscopic materials to achieve multi-scale ordered motion. Although traditional methods have successfully embedded molecular motors into supramolecular systems, the closely packed structure limits the free rotation of molecular motors and affects their applications in complex environments. In recent years, photo-responsive units have been integrated into crystalline porous materials (CPMs), and their pore spaces can be used to enhance the multi-scale motion of molecular motors. Some progress has been made in metal-organic frameworks (MOFs) in this field, but their sensitivity to solvent removal limits their application potential. In contrast, covalent organic frameworks (COFs) have better stability and higher porosity, making them an ideal platform for integrating molecular machines. Nevertheless, the functions of photo-responsive molecular motors in two-dimensional COFs are still limited by low concentration and limited rotational space.

[0003] Three-dimensional covalent organic frameworks (3D COFs) are composed of organic building units connected by strong covalent bonds to form a highly ordered three-dimensional network structure, with high porosity and stability. Compared with two-dimensional COFs, 3D COFs not only provide larger free space but also have more flexible structure regulation capabilities, and are expected to significantly alleviate the steric hindrance suffered by molecular motor motion. However, due to the complex structure, large volume, and susceptibility to steric hindrance interference of the motor units themselves, their directional embedding in three-dimensional covalent organic frameworks is extremely challenging; during the synthesis process, problems such as difficult crystallization, topological disorder, and low motor assembly efficiency are often faced, resulting in the long-term failure to achieve three-dimensional motor COFs with a clear topological structure and high crystallinity. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a three-dimensional molecular motor covalent organic framework material, aiming to solve the problems proposed in the above background art.

[0005] The embodiments of the present invention are implemented as follows. A three-dimensional molecular motor covalent organic framework material contains the following structural units:

[0006]

[0007] In the formula, the "wavy line" represents a -C=N- linking bond;

[0008] The structural units are connected three-dimensionally in space to form an infinitely extended crystal framework structure.

[0009] Preferably, the covalent organic framework material is tetragonal, space group P-4, and the unit cell parameters are as follows: α = 90.00°, β = 90.00°, γ = 90.00°, where a and b in the unit cell parameters are the side lengths of the tetragonal system, c is the short height of the tetragonal system, α is the angle between side a and side c, β is the angle between side b and side c, and γ is the angle between side a and side b.

[0010] Preferably, the average pore size of the covalent organic framework material is 1.8 - 2.1 nm, and the specific surface area is 100 - 500 m 2 / g.

[0011] Another object of the embodiments of the present invention is to provide a preparation method of a three-dimensional molecular motor covalent organic framework material, comprising the following steps:

[0012] Performing a dehydration condensation reaction on an aldehyde monomer and an amino monomer in the presence of a catalyst and a solvent to obtain a crude product;

[0013] Washing, filtering, and drying the crude product to obtain a three-dimensional molecular motor covalent organic framework material;

[0014] Among them, the aldehyde monomer is 4,4'-(9-(2-methyl-2,3-dihydro-1H-cyclopenta[a]naphthalen-1-ylidene)-9H-fluorene-2,7-diyl) dibenzaldehyde, and the structural formula is:

[0015]

[0016] The amino monomer is tetra(2-fluoro-4-aminobiphenyl)methane, and the structural formula is:

[0017]

[0018] Preferably, the molar ratio of the aldehyde monomer to the amino monomer is 1:0.2 - 0.8; more preferably 1:0.4 - 0.5; more preferably 1:0.45 - 0.55; more preferably 1:0.5.

[0019] Preferably, the catalyst is one or more of formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid; more preferably acetic acid and / or trifluoromethanesulfonic acid.

[0020] Preferably, the molar ratio of the aldehyde monomer to the catalyst is 1:5 - 50; more preferably 1:5 - 30; more preferably 1:15 - 20.

[0021] Preferably, the solvent is one or more of 1,4-dioxane, tetrahydrofuran, 1,3,5-trimethylbenzene, toluene, 1,2-dichlorobenzene, N-methylpyrrolidone, dimethylacetamide, ethanol, and deionized water; more preferably, it is one or more of 1,4-dioxane, tetrahydrofuran, 1,3,5-trimethylbenzene, and 1,2-dichlorobenzene; even more preferably, it is 1,3,5-trimethylbenzene.

[0022] Preferably, the mass ratio of the aldehyde monomer to the solvent is 1:30 to 75; more preferably, it is 1:50 to 60.

[0023] Preferably, the reaction temperature of the dehydration condensation reaction is 80 to 150 °C, and the time is 24 to 200 h; more preferably, it is 90 to 140 °C, 48 to 120 h; even more preferably, it is 100 to 130 °C, 60 to 80 h.

[0024] In the embodiments of the present invention, a novel three-dimensional molecular motor covalent organic framework material is constructed for the first time by combining two functional monomers;

[0025] The prepared three-dimensional molecular motor covalent organic framework material has a clear crystal structure and high crystallinity, and at the same time exhibits a high specific surface area, regular and ordered pore arrangement, and uniformly distributed microporous structure, providing an ideal platform for subsequent structure-activity relationship research; it has excellent light response ability, greatly expanding the application of molecular motor-based COF materials in the field of stimulus response;

[0026] The prepared three-dimensional molecular motor covalent organic framework material successfully realizes the integration of the light-responsive motor unit in the three-dimensional COF network, has excellent light response ability, and significantly expands the application boundary of motor-based COF materials in the fields of stimulus response and intelligent materials;

[0027] The preparation method provided by the embodiments of the present invention has easily available raw materials, mild conditions, simple steps, few by-products, and is suitable for large-scale preparation, having good practical application and promotion potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the PXRD result and its simulated value of the three-dimensional molecular motor covalent organic framework prepared in Example 1 of the present invention;

[0029] Figure 2 It is the nitrogen adsorption and desorption curve of the three-dimensional molecular motor covalent organic framework prepared in Example 1 of the present invention;

[0030] Figure 3 It is the solid-state nuclear magnetic carbon spectrum of the three-dimensional molecular motor covalent organic framework prepared in Example 1 of the present invention;

[0031] Figure 4IR characterization of the three-dimensional molecular motor covalent organic framework prepared in Example 1 of the present invention;

[0032] Figure 5 TG analysis curve of the three-dimensional molecular motor covalent organic framework prepared in Example 1 of the present invention;

[0033] Figure 6 SEM image of the three-dimensional molecular motor covalent organic framework prepared in Example 1 of the present invention;

[0034] Figure 7 TEM image of the three-dimensional molecular motor covalent organic framework prepared in Example 1 of the present invention;

[0035] Figure 8 Structure schematic diagram of the three-dimensional molecular motor covalent organic framework prepared in Example 1 of the present invention. Detailed implementation manners

[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] 4,4'-(9-(2-Methyl-2,3-dihydro-1H-cyclopenta[a]naphthalen-1-ylidene)-9H-fluorene-2,7-diyl)dibenzaldehyde used in the embodiments of the present invention was purchased from Guangdong Rongyan Chemical Technology Co., Ltd., and tetrakis(2-fluoro-4-aminobiphenyl)methane was purchased from Guangdong Rongyan Chemical Technology Co., Ltd. Other reagents are all commercially available chemical reagents without special restrictions.

[0038] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0039] Example 1. A three-dimensional molecular motor covalent organic framework material, and its preparation method includes the following steps:

[0040] S1. Dissolve 4,4'-(9-(2-methyl-2,3-dihydro-1H-cyclopenta[a]naphthalen-1-ylidene)-9H-fluoren-2,7-diyl)dibenzaldehyde (55.2 mg, 0.10 mmol) and tetrakis(2-fluoro-4-aminobiphenyl)methane (37.8 mg, 0.05 mmol) in a mixed solution of 1,3,5-trimethylbenzene (0.5 mL) and 9 M acetic acid aqueous solution (0.1 mL), and add it into a hard glass tube with an inner diameter of 8 mm and an outer diameter of 10 mm. Subsequently, quickly freeze the glass tube in liquid nitrogen (77 K), evacuate to 0.15 mmHg, and then seal the tube by flame. After sealing, the tube length is approximately shortened to 13.0 cm. Place the reaction tube in an oven at 120 °C and heat for 5 days. After the reaction is completed, collect the obtained brown precipitate by filtration through a medium-porosity glass filter, and wash it thoroughly with DMF (3 × 20.0 mL), THF (3 × 20.0 mL), and acetone (3 × 20.0 mL) in sequence. Then replace the solvent with anhydrous acetone and dry it under vacuum at 80 °C to finally obtain the crude product JUC-665 in the form of a yellow powder.

[0041] S2. Wash the crude product obtained in S1 five times with acetone and n-hexane respectively, filter, and place the obtained solid in a vacuum drying oven at 110 °C for 3 h to obtain the three-dimensional molecular motor COF (the structure is as shown in Figure 8 ), and the yield is 77%.

[0042] Example 2. Compared with Example 1, the only difference is that the temperature of the dehydration polycondensation reaction in step S1 is adjusted to 100 °C to prepare the three-dimensional molecular motor COF, and the yield is 47%.

[0043] Example 3. Compared with Example 1, the only difference is that the temperature of the dehydration polycondensation reaction in step S1 is adjusted to 130 °C to prepare the three-dimensional molecular motor COF, and the yield is 73%.

[0044] Example 4. Compared with Example 1, the only difference is that the amount of acetic acid in step S1 is adjusted to 0.067 mL to prepare the three-dimensional molecular motor COF, and the yield is 71%.

[0045] Example 5. Compared with Example 1, the only difference is that the 9 M acetic acid aqueous solution (0.1 mL) in step S1 is replaced with 0.1099 mg (0.9 mmol) of benzoic acid to prepare the three-dimensional molecular motor COF, and the yield is 61%.

[0046] Example 6. Compared with Example 1, the only difference is that the 1,3,5-trimethylbenzene (0.5 mL) in step S1 is replaced with 2.07 g of tetrahydrofuran to prepare an amorphous three-dimensional molecular motor COF, and the yield is 63%.

[0047] Performance test:

[0048] 1. X-ray powder diffraction spectroscopy characterization:

[0049] The product finally prepared in Example 1 was taken for PXRD analysis: It was carried out using a Malvern Panalytical Empyrean intelligent X-ray powder diffractometer. The test conditions were: Cu Kα ray (Kα = 0.154 nm), working current 40 mA, working voltage 40 kV, nickel filter, scanning range 2° - 40°; The analysis results were compared with the XRD simulation values of the software Material Studio 2020 to determine the product structure. Among them, in Material Studio 2020, the crystal data was obtained by simulating the experimentally obtained XRD data and gradually adjusting the unit cell parameters (a, b, c and α, β, γ) to make the diffraction peak positions and intensities of the simulated XRD pattern match those of the experimental data. As Figure 1 shown, these optimized unit cell parameters were used to construct the crystal model of the COF, thereby determining its framework structure. Finally, the COF crystal structure that conforms to the experimental results was built in this way. The analysis results are shown in Table 1:

[0050] Table 1

[0051]

[0052] As can be seen from Table 1, the obtained product is a three-dimensional tetragonal structure;

[0053] 2. N2 adsorption-desorption performance analysis:

[0054] The product finally prepared in Example 1 was tested for specific surface area, N2 adsorption-desorption and CO2 adsorption-desorption performance, and was measured using an ASAP 2060 specific surface area analyzer;

[0055] The N2 adsorption-desorption test method was as follows: 50 mg of COF solid was taken and pretreated at 100 °C under vacuum for 8 h. At the liquid nitrogen temperature of -196 °C, the adsorption and desorption amounts of nitrogen by the sample under different relative pressures p / p0 were measured to obtain the nitrogen adsorption-desorption isotherm curve. The obtained results are as Figure 2 shown. It can be seen from Figure 2 that the prepared product has pores, providing sufficient space for the functionalization of motor molecules;

[0056] 3. Solid-state nuclear magnetic carbon spectrum (13C CP / MAS NMR) characterization:

[0057] The product finally prepared in Example 1 was tested by 13C cross-polarization / magic angle spinning nuclear magnetic (CP / MAS NMR) using a Bruker AVANCE III 400 MHz solid-state nuclear magnetic resonance spectrometer at a spinning rate of 10 kHz. Figure 3 For the 13C CP / MAS NMR spectrum, a typical imine C=N signal appears at δ≈161 ppm, and the aromatic ring carbon signals are mainly distributed between δ≈110–145 ppm, indicating that the aldehyde group and the amino group have successfully condensed to form an imine bond during the reaction and the structure is completely assembled.

[0058] 4. Infrared spectroscopy analysis:

[0059] The product finally prepared in Example 1 was characterized by infrared spectroscopy, and the results are as Figure 4 shown. It can be seen from Figure 4 that the product contains a typical absorption peak of the C=N imine bond at 1626 cm -1 , proving the success of polycondensation.

[0060] 5. Thermogravimetric analysis:

[0061] The product finally prepared in Example 1 was tested by thermogravimetric analysis using a SHIMADZU DTG-60 thermal analyzer. The test conditions were: the temperature range was from 30 °C to 800 °C, and it was carried out in a nitrogen environment at a heating rate of 10 °C min -1 , and the nitrogen flow rate was 30 mL min -1 . The results are as Figure 5 shown. It can be seen from Figure 5 that the mass of the product hardly shows significant loss before 300 °C, indicating that the material has good thermal stability in this temperature range.

[0062] 6. Scanning electron microscope (SEM) characterization:

[0063] The surface morphology of the product finally prepared in Example 1 was characterized using a Hitachi S-4800 field emission scanning electron microscope. The product was observed at an accelerating voltage of 5.0 kV after metal spraying treatment. The results are as Figure 6 shown. It can be seen from Figure 6 that the product presents a uniform rod-like morphology with a concentrated particle size distribution, showing good crystallinity.

[0064] 7. Transmission electron microscope (TEM) characterization:

[0065] The microstructure of the product finally prepared in Example 1 was observed using a JEOL JEM-2100 transmission electron microscope at an operating voltage of 200 kV. The results are as Figure 7As shown, it can be seen that it is a uniform crystal packing.

[0066] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A three-dimensional molecular motor covalent organic framework material, characterized in that, The material contains structural units as shown below: In the formula, the "wavy line" represents a -C=N- linking bond; The structural units are connected in a three-dimensional manner in space to form an infinitely extending crystal framework structure.

2. The three-dimensional molecular motor covalent organic framework material according to claim 1, wherein The covalent organic framework material is a tetragonal crystal system, space group P-4, and the unit cell parameters are as follows: α = 90.00°, β = 90.00°, γ = 90.00°, where a and b in the unit cell parameters are the side lengths of the tetragonal crystal system, c is the short height of the tetragonal crystal system, α is the angle between side a and side c, β is the angle between side b and side c, and γ is the angle between side a and side b.

3. The three-dimensional molecular motor covalent organic framework material according to claim 1, characterized in that The average pore diameter of the covalent organic framework material is 1.8 to 2.1 nm, and the specific surface area is 100 to 500 m 2 / g.

4. A method for preparing a three-dimensional molecular motor covalent organic framework material as described in any one of claims 1-3, characterized in that, It includes the following steps: Performing a dehydration condensation reaction on an aldehyde monomer and an amino monomer in the presence of a catalyst and a solvent to obtain a crude product; Washing, filtering, and drying the crude product to obtain a three-dimensional molecular motor covalent organic framework material; Among them, the aldehyde monomer is 4,4'-(9-(2-methyl-2,3-dihydro-1H-cyclopenta[a]naphthalen-1-ylidene)-9H-fluorene-2,7-diyl) dibenzaldehyde, and the structural formula is: The amino monomer is tetrakis(2-fluoro-4-aminobiphenyl)methane, and the structural formula is:

5. The preparation method of the three-dimensional molecular motor covalent organic framework material according to claim 4, characterized in that, The molar ratio of the aldehyde monomer to the amino monomer is 1:0.2 - 0.

8.

6. The preparation method of the three-dimensional molecular motor covalent organic framework material according to claim 4, wherein The catalyst is one or more of formic acid, acetic acid, propionic acid, butyric acid, benzoic acid, trifluoromethanesulfonic acid, and p-toluenesulfonic acid.

7. The preparation method of the three-dimensional molecular motor covalent organic framework material according to claim 4, wherein The molar ratio of the aldehyde monomer to the catalyst is 1:5 - 50.

8. The preparation method of the three-dimensional molecular motor covalent organic framework material according to claim 4, wherein, The solvent is one or more of 1,4-dioxane, tetrahydrofuran, 1,3,5-trimethylbenzene, toluene, 1,2-dichlorobenzene, N-methylpyrrolidone, dimethylacetamide, ethanol, and deionized water.

9. The preparation method of the three-dimensional molecular motor covalent organic framework material according to claim 4, wherein The mass ratio of the aldehyde monomer to the solvent is 1:30 - 75.

10. The preparation method of the three-dimensional molecular motor covalent organic framework material according to claim 4, characterized in that, The reaction temperature of the dehydration condensation reaction is 80 - 150 °C, and the time is 24 - 200 h.

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