A post-synthetic modified functionalized covalent organic framework material, its preparation method and application

Abstract

The application discloses a post-synthesis modified functionalized covalent organic framework material and a preparation method and application thereof; on the basis of an alkyne functionalized covalent organic framework material, the alkyne is post-synthesis modified to form a stable free radical framework and a COF two-dimensional layered structure, so that the post-synthesis modified functionalized covalent organic framework material has a relatively wide absorption spectrum and is favorable to absorption of sunlight. After simulation sunlight irradiation, the temperature can reach 67-68 DEG C, and the post-synthesis modified functionalized covalent organic framework material has a good application prospect as a light-heat conversion material. The preparation method for post-synthesis modification of the alkyne has a high yield and can be prepared on a large scale.

Description

Technical Field

[0001] This invention belongs to the field of organic framework functional materials technology, and relates to a post-synthetic modified functionalized covalent organic framework material, its preparation method and application. Background Technology

[0002] Covalent organic frameworks (COFs) are an emerging class of crystalline and porous polymers that allow π-conjugated organic building blocks to covalently assemble into ordered structures. A key characteristic of COFs is their designability, where different functional units can be directly introduced through de novo or post-synthetic strategies. COFs are ideal candidates for photothermal materials because the face-to-face stacking of COF layers significantly reduces radiative attenuation and increases non-radiative attenuation. Different organic units and chemical doping methods can participate in the COF platform, encoding radicals, charge transfer (CT), and ionic substances into the COF framework. These substances exhibit broad absorption extending into the near-infrared (NIR) region but are forbidden from emission. However, to date, these strategies have encountered several key obstacles, including complex framework design, cumbersome synthesis, low crystallinity, and unstable doped states.

[0003] Post-synthetic modification is a strategy for synthesizing porous framework materials. In crystalline porous framework materials, organic linking units allow for convenient variation in the size and function of open channels. Typically, functional branches are attached to the backbone of ligand molecules to facilitate reaction with incoming guest reagents within the assembled framework. For example, crosslinking agents can covalently bridge individual linkers, transforming the coordination framework into a stronger, more stable covalent network. By selecting different branches and guests, even conjugated bridges (e.g., alkenes, oligothiophenes, and metal thiols) can be constructed to promote electronic interactions between organic linking molecules, thereby achieving better electrical conductivity and catalytic performance. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the first objective of this invention is to provide a post-synthetic modified functionalized covalent organic framework material with a wide light absorption range and stable free radical photothermal conversion performance.

[0005] The second objective of this invention is to provide a method for preparing post-synthetic modified functionalized covalent organic framework materials, which can be prepared in high yield and on a large scale through a post-synthetic modification process.

[0006] The third objective of this invention is to provide an application of post-synthesized modified functionalized covalent organic framework materials.

[0007] The first objective of this invention can be achieved by adopting the following technical solution:

[0008] A post-synthetic modified functionalized covalent organic framework material is obtained by modifying the alkynyl group in the covalent organic framework of the structural unit shown in Formula I with a compound of the structure shown in Formula II or Formula III through a CA-RE reaction.

[0009] The structural unit shown in Equation I is:

[0010]

[0011] The compound with the structure shown in Formula II is:

[0012]

[0013] The compound with the structure shown in Formula III is:

[0014]

[0015] Furthermore, it has the structural unit shown in Equation IV or Equation V:

[0016]

[0017] Furthermore, the post-synthesized functionalized covalent organic framework material has an absorption spectrum in the visible and near-infrared light range.

[0018] Furthermore, the post-synthesized functionalized covalent organic framework material has an absorption spectrum in the range of 220-1800 nm.

[0019] The second objective of this invention can be achieved by adopting the following technical solution:

[0020] A method for preparing a post-synthetic modified functionalized covalent organic framework material includes the following steps:

[0021] The covalent organic framework of the structural unit shown in Formula I is heated and reacted with the structural compound shown in Formula II and / or Formula III under vacuum. After the reaction is completed, the post-synthesized and modified functionalized covalent organic framework material is obtained.

[0022] The structural unit shown in Equation I is:

[0023]

[0024] The compound with the structure shown in Formula II is:

[0025]

[0026]

[0027] The compound with the structure shown in Formula III is:

[0028]

[0029] Furthermore, the heating reaction conditions are 140-190℃; the reaction time is 6-72h.

[0030] Furthermore, the mass ratio of the covalent organic framework of the structural unit shown in Formula I to the structural compound shown in Formula II or Formula III is (0.7-1):1.

[0031] Furthermore, after the reaction is completed, post-processing is carried out, which includes purifying the reaction product with organic reagents and then vacuum drying it.

[0032] Furthermore, the organic reagent is one or more of acetonitrile, ethyl acetate, or tetrahydrofuran.

[0033] Further purification includes using Soxhlet extraction methods.

[0034] Furthermore, the covalent organic framework of the structural unit shown in Formula I is spatially separated from the structural compound shown in Formula II and does not come into direct contact.

[0035] The COF of the structural unit shown in Formula I is fully mixed with the structural compound shown in Formula III.

[0036] Furthermore, a method for preparing a covalent organic framework comprising the structural unit shown in Formula I is as follows: 1,3,6,8-tetra(formaldehyde-phenyl)-pyrene and 4,4',4”,4”'-[pyrene-1,3,6,8-tetramethyltetra(acetylene-2,1-diyl)]tetraphenylamine are reacted under solvothermal conditions via an ammonia-aldehyde condensation reaction to obtain the covalent organic framework comprising the structural unit shown in Formula I.

[0037] The third objective of this invention can be achieved by adopting the following technical solution:

[0038] The application of a post-synthetic modified functionalized covalent organic framework material prepared by any of the above-described methods as a photothermal conversion material.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] 1. The present invention discloses a post-synthetic modified functionalized covalent organic framework material, which is based on an alkynyl functionalized covalent organic framework material, and the alkynyl group is post-synthetic modified to form a stable free radical framework and a two-dimensional layered COF structure. The two-dimensional layered stacking structure has a highly conjugated rigid planar skeleton, resulting in strong π-π stacking between molecules, which further enhances the stability of free radicals. Therefore, the post-synthetic modified functionalized covalent organic framework material has a broad absorption spectrum, which is beneficial for the absorption of sunlight.

[0041] 2. The present invention provides a post-synthetic modified functionalized covalent organic framework material, which is based on an alkynyl functionalized covalent organic framework material, and the alkynyl group is post-synthetic modified. This preparation through the post-synthetic modification process has a high yield and can be prepared on a large scale.

[0042] 3. An application of a post-synthesized functionalized covalent organic framework material of the present invention. The post-synthesized functionalized covalent organic framework material possesses a functionalized free radical covalent organic framework. It exhibits a broad absorption spectrum and high photothermal conversion performance. After simulated sunlight irradiation, the temperature can reach 67-68℃, showing great application prospects as a photothermal conversion material. Attached Figure Description

[0043] Figure 1 X-ray powder diffraction patterns of TAEPy-COF prepared in Example 1, TAEPy-COF-T1 prepared in Example 2, and TAEPy-COF-T2 prepared in Example 5;

[0044] Figure 2 Fourier transform-infrared spectra of TAEPy-COF prepared in Example 1, TAEPy-COF-T1 prepared in Example 2, and TAEPy-COF-T2 prepared in Example 5;

[0045] Figure 3 The UV-Vis-NIR absorption spectra of TAEPy-COF prepared in Example 1, TAEPy-COF-T1 prepared in Example 2, and TAEPy-COF-T2 prepared in Example 5 at room temperature are shown.

[0046] Figure 4 The graph shows the solid EPR test results of TAEPy-COF prepared in Example 1, TAEPy-COF-T1 prepared in Example 2, and TAEPy-COF-T2 prepared in Example 5.

[0047] Figure 5The graph shows the temperature change over time under simulated sunlight irradiation for TAEPy-COF prepared in Example 1, TAEPy-COF-T1 prepared in Example 2, and TAEPy-COF-T2 prepared in Example 5. Detailed Implementation

[0048] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0049] Most existing photothermal materials used in solar water evaporation systems are complex to prepare and cannot be mass-produced. These include composite materials such as membranes, porous aerogels and foams, three-dimensional (3D) wood supports, and hydrogels. They also suffer from problems such as limited light absorption range, poor water transport capacity, low photothermal conversion efficiency, or short service life.

[0050] The one-dimensional porous structure of carbon-based organic frameworks (COFs) provides numerous channels for water transport, thus ensuring sufficient water transport capacity for water vapor generation. However, due to the inherent hydrophobicity and limited light absorption of COFs, most current COF-based solar water evaporation systems require the addition of additional hybrid materials, such as composite carbon-based materials (e.g., graphene or carbon nanotubes), to achieve good light absorption and tunable water transport pathways, which limits the application of COF materials. Therefore, this invention provides a post-synthetic modified functionalized covalent organic framework material, its preparation method, and its applications.

[0051] A post-synthetic modified functionalized covalent organic framework material is obtained by modifying the alkynyl group in the covalent organic framework of the structural unit shown in Formula I with a compound of the structure shown in Formula II or Formula III through a CA-RE reaction.

[0052] The structural unit shown in Equation I is:

[0053]

[0054] The compound with the structure shown in Formula II is:

[0055]

[0056] The compound with the structure shown in Formula III is:

[0057]

[0058] The covalent organic framework of the structural unit shown in Formula I is an alkyne-functionalized covalent organic framework material with a unique two-dimensional layered stacking structure and a one-dimensional channel structure. The alkyne groups within it can react with various groups, thus enabling post-synthetic modification of the covalent organic framework of the structural unit shown in Formula I. This invention performs a [2+2]CA-RE reaction on the alkyne groups in the covalent organic framework of the structural unit shown in Formula I. The pyrene groups are strong electron donors, which can increase the electron density of the alkyne units in the COF grid and promote the CA-RE reaction with the electrophilic compound TCNE (Structure II) and compound TCNQ (Structure III) as guests.

[0059] The post-synthesized modified product maintains the covalent organic framework structure while forming a framework with stable free radicals. The unique two-dimensional layered stacking structure of COF has a highly conjugated rigid planar skeleton, resulting in strong π-π stacking between molecules, which enhances the stability of free radicals. This not only increases the hydrophilicity of the material but also gives it a wide light absorption range and good photothermal conversion performance.

[0060] As one implementation, it has the structural unit shown in Formula IV or Formula V:

[0061]

[0062] The alkynyl group in the covalent organic framework of the structural unit shown in Formula I reacts with tetracyanoethylene to obtain a post-synthetic modified functionalized covalent organic framework material with the structural unit shown in Formula IV; and reacts with 7,7,8,8-tetracyanobenzoquinone dimethane to obtain a post-synthetic modified functionalized covalent organic framework material with the structural unit shown in Formula V. Photothermal materials with a wide light absorption range and stable free radicals are obtained through post-synthetic modification.

[0063] As one embodiment, the post-synthesized functionalized covalent organic framework material has an absorption spectrum in the visible and near-infrared light range. In this embodiment, the post-synthesized functionalized covalent organic framework material has an absorption spectrum in the range of 200-1800 nm; preferably, the post-synthesized functionalized covalent organic framework material has an absorption spectrum in the range of 220-1800 nm.

[0064] A method for preparing a post-synthetic modified functionalized covalent organic framework material includes the following steps:

[0065] The covalent organic framework of the structural unit shown in Formula I is heated and reacted with the structural compound shown in Formula II and / or Formula III under vacuum. After the reaction is completed, the post-synthesized and modified functionalized covalent organic framework material is obtained.

[0066] The structural unit shown in Equation I is:

[0067]

[0068] The compound with the structure shown in Formula II is:

[0069]

[0070] The compound with the structure shown in Formula III is:

[0071]

[0072] The covalent organic framework (COF) of the structural unit shown in Formula I has a two-dimensional layered stacking structure and a one-dimensional pore structure. The alkynyl group provides sites for post-synthetic modification. Therefore, this invention uses the covalent organic framework of the structural unit shown in Formula I as a raw material for post-synthetic modification, performing a [2+2]CA-RE reaction on the alkynyl group. Specifically, the alkynyl group in the covalent organic framework of the structural unit shown in Formula I reacts with tetracyanoethylene or 7,7,8,8-tetracyanobenzoquinone dimethane to obtain the corresponding post-synthetic modified functionalized covalent organic framework material. Based on the structure and properties of COF, a framework with stable free radicals is formed. The unique two-dimensional layered stacking structure of COF, with its highly conjugated rigid planar skeleton, leads to strong intermolecular π-π stacking, enhancing the stability of free radicals. Based on the alkynyl functionalized covalent organic framework material, the alkynyl group is post-synthetically modified. This preparation process via post-synthetic modification has high yield and can be prepared on a large scale.

[0073] In one embodiment, the heating reaction conditions are 140-190°C; the reaction time is 6-72 h. The heating reaction temperature is required to allow tetracyanoethylene or 7,7,8,8-tetracyanobenzoquinone dimethane to vaporize in a vacuum, and the vaporized gas reacts fully with the covalent organic framework of the structural unit shown in Formula I; in this embodiment, the vacuum condition is a vacuum degree of 0.1 MPa.

[0074] As one implementation, the covalent organic framework of the structural unit shown in Formula I is spatially separated from the structural compound shown in Formula II and does not come into direct contact.

[0075] A covalent organic framework having the structural unit shown in Formula I is placed in a reactor without contact with tetracyanoethylene; after the reactor is evacuated, it is heated. In this embodiment, the covalent organic framework having the structural unit shown in Formula I is placed in a Schlenk tube, while tetracyanoethylene is placed in a smaller tube, and the smaller tube containing tetracyanoethylene is placed in a Schlenk tube.

[0076] The COF of the structural unit shown in Formula I is thoroughly mixed with the structural compound shown in Formula III. Alternatively, the covalent organic framework of the structural unit shown in Formula I can be directly and thoroughly mixed with the structural compound shown in Formula III.

[0077] In one embodiment, the mass ratio of the covalent organic framework of the structural unit shown in Formula I to the structural compound shown in Formula II or Formula III is (0.7-1):1.

[0078] As one implementation method, a post-processing is performed after the reaction is completed. The post-processing includes purifying the reaction product using organic reagents and then vacuum drying it.

[0079] In this embodiment, the purification process involves first washing the reaction product with an organic reagent. Washing methods include dissolution, solid-liquid separation, and Soxhlet extraction. Preferably, the washing process involves first dissolving the reaction product in an organic solvent, followed by solid-liquid separation, and then processing the solid material using Soxhlet extraction.

[0080] As one embodiment, the organic reagent is one or more of acetonitrile, ethyl acetate, or tetrahydrofuran.

[0081] As one embodiment, a method for preparing a covalent organic framework comprising the structural unit shown in Formula I is provided: 1,3,6,8-tetra(formaldehyde-phenyl)-pyrene and 4,4',4”,4”'-[pyrene-1,3,6,8-tetramethyltetra(acetylene-2,1-diyl)]tetraphenylamine are subjected to an ammonia-aldehyde condensation reaction under solvothermal conditions to obtain the covalent organic framework comprising the structural unit shown in Formula I.

[0082] In one embodiment, the molar ratio of 1,3,6,8-tetra(formaldehyde-phenyl)-pyrene and 4,4',4”,4”'-[pyrene-1,3,6,8-tetramethyltetra(acetylene-2,1-diyl)]tetraphenylamine is (0.8-1.2):1.

[0083] As one implementation method, the solvothermal reaction conditions are 100-150°C for 24-96 hours.

[0084] In one embodiment, the solvent for the reaction is 1,4-dioxane.

[0085] In one implementation method, the catalyst for the reaction is acetic acid; the concentration of acetic acid is 3-8 mol / L.

[0086] In one embodiment, the volume ratio of acetic acid to 1,4-dioxane is (0.1-2):1.

[0087] The following is a further explanation using specific embodiments.

[0088] Example 1

[0089] Preparation of TAEPy-COF:

[0090] Weigh 0.05 mmol of 4,4',4”,4”'-[pyrene-1,3,6,8-tetramethyltetra(ethynyl-2,1-diyl)]tetraphenylamine (TAEPy) and 0.05 mmol of 1,3,6,8-tetra(formaldehyde-phenyl)-pyrene (Py4CHO) into an 8×150 mm glass tube, add 1.0 mL of 1,4-dioxane and 0.1 mL of 6 M acetic acid aqueous solution, and then sonicate for 10 min. Seal the glass tube with an oxyhydrogen flame and heat it in an oven at 120 °C for 72 h, then let it cool naturally to room temperature. Collect the solid by filtration, wash the powder sample with DMF (5 mL×5) and EA (5 mL×5), then Soxhlet extract it in THF solution for 3 days, and dry it in vacuum to obtain the covalent organic framework powder with the structural unit shown in Formula I, named TAEPy-COF.

[0091] Example 2

[0092] Preparation of TAEPy-COF-T1:

[0093] 60 mg of TAEPy-COF from Example 1 was weighed and placed in a 25 mL Schlenk tube. 51 mg of tetracyanoethylene (TCNE) was weighed and placed in a smaller tube. The smaller tube was placed inside the Schlenk tube to keep TAEPy-COF and tetracyanoethylene spatially separated to prevent direct contact. Air was evacuated from the Schlenk tube and it was placed in an oven preheated to 140 °C to promote the sublimation and vapor transport of tetracyanoethylene. After reacting for 24 h, the tube was removed from the oven and cooled to room temperature. The resulting powder was washed with MeCN and EA, subjected to Soxhlet extraction with THF for 3 days, and dried under vacuum at 100 °C for 5 h to obtain a post-synthesized modified functionalized covalent organic framework material of the structural unit shown in IV, named TAEPy-COF-T1.

[0094] Example 3

[0095] Preparation of TAEPy-COF-T1:

[0096] 60 mg of TAEPy-COF from Example 1 was weighed and placed in a 25 mL Schlenk tube. 60 mg of tetracyanoethylene (TCNE) was weighed and placed in a smaller tube. The smaller tube was placed inside the Schlenk tube to keep TAEPy-COF and tetracyanoethylene spatially separated to prevent direct contact. Air was evacuated from the Schlenk tube and it was placed in an oven preheated to 150 °C to promote the sublimation and vapor transport of tetracyanoethylene. After reacting for 36 h, the tube was removed from the oven and cooled to room temperature. The resulting powder was washed with MeCN and EA, subjected to Soxhlet extraction with THF for 3 days, and dried under vacuum at 100 °C for 5 h to obtain a post-synthesized modified functionalized covalent organic framework material of the structural unit shown in IV, named TAEPy-COF-T1.

[0097] Example 4

[0098] Preparation of TAEPy-COF-T1:

[0099] 60 mg of TAEPy-COF from Example 1 was weighed and placed in a 25 mL Schlenk tube. 80 mg of tetracyanoethylene (TCNE) was weighed and placed in a smaller tube. The smaller tube was placed inside the Schlenk tube to keep TAEPy-COF and tetracyanoethylene spatially separated to prevent direct contact. Air was evacuated from the Schlenk tube and it was placed in an oven preheated to 160 °C to promote the sublimation and vapor transport of tetracyanoethylene. After reacting for 48 h, the tube was removed from the oven and cooled to room temperature. The resulting powder was washed with MeCN and EA, subjected to Soxhlet extraction with THF for 3 days, and dried under vacuum at 100 °C for 5 h to obtain a post-synthesized modified functionalized covalent organic framework material of the structural unit shown in IV, named TAEPy-COF-T1.

[0100] Example 5

[0101] Preparation of TAEPy-COF-T2:

[0102] 60 mg of TAEPy-COF from Example 1 and 52 mg of 7,7,8,8-tetracyanobenzoquinone dimethyl ether (TCNQ) were weighed and placed in an 8×150 mm glass tube to ensure full contact between the two. The air in the glass tube was evacuated and kept under vacuum. The tube was then placed in an oven preheated to 180 °C to promote the sublimation of 7,7,8,8-tetracyanobenzoquinone dimethyl ether. After reacting for 24 h, the tube was removed from the oven and cooled to room temperature. The resulting powder was washed with MeCN and EA, subjected to Soxhlet extraction with THF for 3 days, and dried under vacuum at 100 °C for 5 h to obtain a post-synthesized modified functionalized covalent organic framework material of the structural unit shown in V, named TAEPy-COF-T2.

[0103] Example 6

[0104] Preparation of TAEPy-COF-T2:

[0105] 60 mg of TAEPy-COF from Example 1 and 85.7 mg of 7,7,8,8-tetracyanobenzoquinone dimethane were weighed and placed in an 8×150 mm glass tube to ensure full contact. The air in the glass tube was evacuated and kept under vacuum. The tube was then placed in an oven preheated to 185°C to promote the sublimation of 7,7,8,8-tetracyanobenzoquinone dimethane. After reacting for 12 h, the tube was removed from the oven and cooled to room temperature. The resulting powder was washed with MeCN and EA, subjected to Soxhlet extraction with THF for 3 days, and dried under vacuum at 100°C for 5 h to obtain a post-synthesized modified functionalized covalent organic framework material of the structural unit shown in V, named TAEPy-COF-T2.

[0106] Example 7

[0107] Preparation of TAEPy-COF-T2:

[0108] 60 mg of TAEPy-COF and 75 mg of 7,7,8,8-tetracyanobenzoquinone dimethane from Example 1 were weighed and placed in an 8×150 mm glass tube to ensure full contact. The air in the glass tube was evacuated and kept under vacuum. The tube was then placed in an oven preheated to 190 °C to promote the sublimation of 7,7,8,8-tetracyanobenzoquinone dimethane. After reacting for 12 h, the tube was removed from the oven and cooled to room temperature. The resulting powder was washed with MeCN and EA, subjected to Soxhlet extraction with THF for 3 days, and dried under vacuum at 100 °C for 5 h to obtain a post-synthesized modified functionalized covalent organic framework material of the structural unit shown in V, named TAEPy-COF-T2.

[0109] Test example:

[0110] (1) X-ray powder diffraction tests were performed on TAEPy-COF prepared in Example 1, TAEPy-COF-T1 prepared in Example 2, and TAEPy-COF-T2 prepared in Example 5. The X-ray powder diffraction results are as follows: Figure 1 As shown; where a is the simulated AA stacking structure, b is the X-ray powder diffraction pattern of TAEPy-COF prepared in Example 1, c is the X-ray powder diffraction pattern of TAEPy-COF-T1 prepared in Example 2, and d is the X-ray powder diffraction pattern of TAEPy-COF-T2 prepared in Example 5.

[0111] from Figure 1The X-ray powder diffraction results show that the diffraction pattern of TAEPy-COF synthesized in Example 1 is highly consistent with the X-ray powder diffraction of the AA-packed structure simulated by Materials Studio software in terms of peak position, indicating that the TAEPy-COF synthesized in Example 1 is a two-dimensional layered structure of AA packing. Furthermore, the diffraction patterns also show that the diffraction peaks of TAEPy-COF are very strong and sharp, indicating that the synthesized covalent organic framework TAEPy-COF has high crystallinity. After post-functionalization modification, the X-ray powder diffraction patterns of TAEPy-COF-T1 prepared in Example 2 and TAEPy-COF-T2 prepared in Example 5 still maintain crystallinity, and the peak positions are consistent with those of the TAEPy-COF prepared in Example 1, indicating that the COF material maintains good crystallinity during the post-functionalization modification process.

[0112] (2) Fourier transform-infrared spectroscopy was performed on TAEPy-COF prepared in Example 1, TAEPy-COF-T1 prepared in Example 2, and TAEPy-COF-T2 prepared in Example 5. The infrared spectra are shown below. Figure 2 As shown; where a is the infrared spectrum of 4,4',4”,4”'-[pyrene-1,3,6,8-tetramethyltetra(acetylene-2,1-dimethyl)]tetraphenylamine (TAEPy); b is the infrared spectrum of TAEPy-COF prepared in Example 1; c is the infrared spectrum of TAEPy-COF-T1 prepared in Example 2; and d is the infrared spectrum of TAEPy-COF-T2 prepared in Example 5.

[0113] from Figure 2 It can be seen that in the Fourier transform infrared spectrum of the TAEPy-COF prepared in Example 1, approximately 3200-3400 cm⁻¹ of the original amino monomer TAEPy was observed. -1 The NH stretching vibration absorption peak disappears at 2189 cm⁻¹, while the absorption peak at 218 -1 The C≡C stretching vibration at this point remains intact. Additionally, it was observed at 1694 cm⁻¹. -1 The absorption peak of the C=O stretching vibration disappears, and at 1618 cm⁻¹... -1 The presence of a C=N stretching vibration absorption peak at 2212 cm⁻¹ indicates that the monomer successfully underwent an ammonia-aldehyde condensation polymerization to form TAEPy-COF. The TAEPy-COF-T1 powder obtained after TCNE treatment showed an absorption peak at 2212 cm⁻¹. -1 The C≡N stretching vibration peak is observed at 2215 cm⁻¹, while the C≡C stretching vibration peak disappears. The TAEPy-COF-T2 powder obtained after TCNQ treatment shows a peak at 2215 cm⁻¹. -1The presence of a C≡N stretching vibration peak and the disappearance of the C≡C stretching vibration peak indicate that the alkynyl functional group successfully reacted with the TCNE and TCNQ guest molecules, achieving post-synthetic modification.

[0114] (3) The TAEPy-COF prepared in Example 1, the TAEPy-COF-T1 prepared in Example 2, and the TAEPy-COF-T2 prepared in Example 5 were subjected to UV-Vis-NIR absorption spectroscopy tests, and the results are as follows: Figure 3 As shown, a is the absorption spectrum of TAEPy-COF prepared in Example 1; b is the absorption spectrum of TAEPy-COF-T1 prepared in Example 2; and c is the absorption spectrum of TAEPy-COF-T2 prepared in Example 5.

[0115] from Figure 3 Compared to the original TAEPy-COF, the post-synthesized and modified TAEPy-COF-T1 and TAEPy-COF-T2 powders showed significant differences in their UV-Vis-NIR absorption spectra measured at room temperature. Both TAEPy-COF-T1 and TAEPy-COF-T2 powders exhibited a broad absorption spectrum of 220-1800 nm, covering the visible and near-infrared light range, which is beneficial for the absorption of sunlight. This is because the introduction of the Donor-Acceptor (DA) structure into the TAEPy-COF-T1 and TAEPy-COF-T2 framework generates strong intramolecular charge transfer and a low band gap, greatly improving non-radiative decay. Therefore, TAEPy-COF-T1 and TAEPy-COF-T2 powders have great potential for applications in solar-thermal conversion and thermoelectric conversion.

[0116] (4) The TAEPy-COF prepared in Example 1, the TAEPy-COF-T1 prepared in Example 2, and the TAEPy-COF-T2 prepared in Example 5 were subjected to electron paramagnetic resonance (EPR) activity tests, and the results are as follows: Figure 4 As shown, the black image represents the EPR signal of TAEPy-COF prepared in Example 1; the red image represents the EPR signal of TAEPy-COF-T1 prepared in Example 2; and the blue image represents the EPR signal of TAEPy-COF-T2 prepared in Example 5.

[0117] Electron paramagnetic resonance (EPR) activity tests were performed on the TAEPy-COF solids prepared in Example 1, TAEPy-COF-T1 prepared in Example 2, and TAEPy-COF-T2 prepared in Example 5. Each sample was 2.0 mg. Figure 4The solids TAEPy-COF-T1 and TAEPy-COF-T2 shown in the figure exhibit a significant EPR signal, while the solid TAEPy-COF shows a negligible EPR signal, indicating that TAEPy-COF-T1 and TAEPy-COF-T2 are rich in stable free radicals.

[0118] Experimental example:

[0119] Under simulated sunlight irradiation (420–2500 nm) using a xenon lamp, the light intensity was 0.1 W / cm². -2 30 mg of TAEPy-COF prepared in Example 1, TAEPy-COF-T1 prepared in Example 2, and TAEPy-COF-T2 prepared in Example 5 were irradiated at room temperature for 5 minutes, after which the light was removed. The changes in TAEPy-COF, TAEPy-COF-T1, and TAEPy-COF-T2 with light exposure time and temperature are shown below. Figure 5 As shown.

[0120] from Figure 5 As can be seen, TAEPy-COF-T1 and TAEPy-COF-T2 powders exhibit highly efficient photothermal conversion. After 5 minutes of light irradiation, the highest temperature of TAEPy-COF-T1 was 67.1℃, and the highest temperature of TAEPy-COF-T2 was 68.0℃, while the original TAEPy-COF did not exceed 55.0℃ under the same conditions. After 5 minutes, the powder surface temperature dropped rapidly upon removal of light irradiation. Therefore, the TAEPy-COF-T1 and TAEPy-COF-T2 obtained after post-synthesis modification demonstrate superior photothermal conversion performance.

[0121] In summary, the post-synthetic modified functionalized covalent organic framework material of this invention, through post-synthetic modification of the alkynyl groups in the alkynyl-functionalized covalent organic framework, forms a covalent organic framework material rich in stable free radicals; it exhibits a broad absorption spectrum of 200-1800 nm, and after simulated sunlight irradiation, the temperature can reach 68℃, demonstrating excellent photothermal conversion performance and promising application prospects as a photothermal conversion material. This method employs a green and efficient post-synthetic modification approach, achieving high yield and enabling large-scale preparation.

[0122] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A post-synthetically modified functionalized covalent organic framework material, characterized in that, The alkyne group in the covalent organic framework of the structural unit shown in formula I is modified by a CA-RE reaction with the compound of the structure shown in formula III to obtain the post-synthetically modified functionalized covalent organic framework material; The structural unit shown in formula I is: Formula I; The compound of the structure shown in formula III is: Formula III; The post-synthetically modified functionalized covalent organic framework material has the structural unit shown in formula V: Formula V.

2. The post-synthetically modified functionalized covalent organic framework material according to claim 1, characterized in that, The post-synthetically modified functionalized covalent organic framework material has an absorption spectrum in the visible and near-infrared light range; the absorption spectrum range is 220-1800 nm.

3. A method of preparing a post-synthetically modified functionalized covalent organic framework material according to claim 1 or 2, characterized in that, The method comprises the following steps: The covalent organic framework of the structural unit shown in formula I is heated and reacted with the compound of the structure shown in formula III under vacuum conditions, and the post-synthetically modified functionalized covalent organic framework material is obtained after the reaction is completed; The structural unit shown in formula I is: Formula I; The compound of the structure shown in formula III is: Formula III.

4. The preparation method of the post-synthetically modified functionalized covalent organic framework material according to claim 3, characterized in that, The heating reaction condition is at 140-190 DEG C; and the reaction time is 6-72 h.

5. The preparation method of the post-synthetically modified functionalized covalent organic framework material according to claim 3, characterized in that, The mass ratio of the covalent organic framework of the structural unit shown in formula I to the compound of the structure shown in formula III is (0.7-1):

1.

6. The preparation method of the post-synthetically modified functionalized covalent organic framework material according to claim 3, characterized in that, After the reaction is completed, post-treatment is further performed, and the post-treatment process comprises purifying the reaction product by using an organic reagent, and vacuum drying after the purification; The organic reagent is one or two or more of acetonitrile, ethyl acetate or tetrahydrofuran; and the purification comprises a Soxhlet extraction method.

7. The preparation method of the post-synthetically modified functionalized covalent organic framework material according to claim 3, characterized in that, The COF of the structural unit shown in formula I is fully mixed with the compound of the structure shown in formula III.

8. The preparation method of the post-synthetically modified functionalized covalent organic framework material according to claim 3, characterized in that, The preparation method of the covalent organic framework comprising the structural unit shown in formula I: 1,3,6,8-tetra (formaldehyde phenyl) -pyrene and 4,4',4'', 4'''-[pyrene-1,3,6,8-tetrakisyl tetra (acetylene-2,1-diyl) ] tetraphenylamine are subjected to an aminoaldehyde condensation reaction under a solvent thermal reaction condition to obtain the covalent organic framework of the structural unit shown in formula I.

9. Application of the post-synthetically modified functionalized covalent organic framework material according to any one of claims 1-2 or the post-synthetically modified functionalized covalent organic framework material prepared by the preparation method of the post-synthetically modified functionalized covalent organic framework material according to any one of claims 3-8 as a light-heat conversion material.

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