A long-wavelength covalent organic framework material with AIE characteristics, and a preparation method and application thereof

Abstract

This invention relates to the field of information encryption technology, specifically to a long-wavelength covalent organic framework material with AIE characteristics, its preparation method, and its applications. The preparation method provided by this invention involves placing 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 2-hydroxy-1,3,5-benzenetriformaldehyde, and an aqueous solution of acetic acid in a Pyrex tube containing solvent, followed by ultrasonication and then freeze-circuiting to obtain a covalent organic framework material containing a Schiff base structure. Using the covalent organic framework material as a starting material, it is mixed with styrene in a solvent, and an oxidant and catalyst are added. Similarly, after ultrasonic dispersion and freeze-circuiting, a long-wavelength covalent organic framework material with AIE characteristics, PM-MT-HBTA-COF, is obtained. The prepared material achieves a fluorescence quantum yield of 6.58% in the aggregated state, with the maximum emission wavelength redshifted from 657 nm before modification to 724 nm. Under 365 nm ultraviolet light excitation, the pattern instantly exhibits deep red fluorescence, demonstrating rapid decryption response and significant contrast.

Description

Technical Field

[0001] This invention relates to the field of information encryption technology, specifically to a long-wavelength covalent organic framework material with AIE properties, its preparation method, and its applications. Background Technology

[0002] Information encryption and anti-counterfeiting technologies are in increasing demand in modern information security, product traceability, and high-end packaging. Traditional encryption technologies, such as QR codes and microtext, are no longer sufficient to meet the requirements of high security, convenient visualization, and user-friendly encryption due to their ease of copying, fragility, or reliance on complex instruments for identification.

[0003] Optical encryption materials, especially fluorescent materials, have become a research hotspot due to their rapid response, diverse modes, and ability to be identified by the naked eye or simple devices. Among them, materials that can emit visible light (especially red light or near-infrared light that the human eye is sensitive to) under specific wavelength excitation have the advantages of low background interference and good penetration, making them more suitable for information reading in complex environments.

[0004] Covalent organic frameworks (COFs), as an emerging class of porous crystalline materials with regular pore structures and high designability, have shown broad application potential in fluorescence sensing, optoelectronic devices, catalysis, and other fields in recent years. Porous crystalline materials possess strong structural designability, high specific surface area, and good chemical stability, making them novel fluorescent densification materials.

[0005] However, most traditional COFs emit fluorescence in short wavelength regions (such as blue and green), which are easily affected by ambient light scattering and substrate autofluorescence. Furthermore, their luminescent groups often cause fluorescence quenching due to π-π* accumulation in the aggregated state (i.e., fluorescence quenching, ACQ effect, easily occurs in the aggregated state). This severely restricts their practical application in high-concentration, aggregated states such as solid-state optical devices, thin films, or printed functional materials (inks). For example, patent CN 116082590 B discloses a COF material and its preparation method and application. It uses 4,4',4'',4'''-(ethylene-1,1,2,2-tetramethyl)tetrabenzaldehyde (ETBA) and 4,4'-diaminodiphenyl ether (ODA), a flexible organic monomer with chelating sites, as raw materials. Methanol and acetic acid are added and the mixture is shaken and dispersed. The mixture is then frozen with liquid nitrogen, and the reaction is carried out in a constant temperature oven under vacuum. The product is collected by filtration, washed with anhydrous N,N-dimethylformamide and tetrahydrofuran, and then washed with anhydrous acetone by centrifugation. The solid product is collected and dried in an oven to obtain yellow ETBA-ODA-COF powder. This invention modulates the π-π interactions in the COF structure to synthesize an ETBA-ODA-COF material with yellow-green fluorescence. Located in the short-wavelength yellow-green region, it is easily affected by ambient light scattering and substrate autofluorescence. Meanwhile, common printing substrates such as paper often exhibit autofluorescence in the blue-green to yellow-green region under excitation light. These two interfering factors severely overlap with the emission band of ETBA-ODA-COF, leading to a significant increase in background noise of the printed pattern, decreased color purity and anti-counterfeiting feature recognition, and difficulty in achieving high signal-to-noise ratio optical reading under complex lighting conditions.

[0006] The emergence of aggregation-induced emission (AIE) materials offers a revolutionary approach to solving the ACQ problem. AIE properties result in weak luminescence in the dispersed state, but significantly enhanced luminescence in the aggregated or solid state, making them highly suitable for printing ink systems requiring high concentration loading, and applicable to scenarios requiring solid-state, high-concentration, or thin-film states.

[0007] Although COFs with AIE properties (AIE-COF) have gradually attracted attention and made some progress in recent years, their synthesis usually relies on complex one-step polymerization, which places extremely stringent requirements on monomer structural design and reaction conditions. Currently, most materials still face problems such as emission wavelengths concentrated in the short-wavelength band, limited solid-state luminescence efficiency, and insufficient processing performance, making it difficult to flexibly control the emission wavelength to the long-wavelength band (such as orange-red to near-infrared). In addition, most reported AIE-COF materials exist in powder form, lacking a functional material system that can be directly adapted to conventional printing processes (such as screen printing) and has both long-wavelength emission and high solid-state fluorescence efficiency. How to process them into stable functional inks suitable for large-scale, low-cost patterned preparation and achieve compatibility with ordinary printing processes (such as screen printing) remains a technical bottleneck. Long-wavelength emission (such as red to near-infrared light) has advantages such as low background interference, strong penetration, and visual recognition friendliness, making it more practical in optical applications such as information encryption and anti-counterfeiting labels.

[0008] Therefore, developing COFs materials that combine long-wavelength AIE characteristics, good processability, and high stability, and realizing their efficient application in screen printing inks, is of great significance for promoting the practical application of COFs in high-end anti-counterfeiting, information security, and smart packaging. Summary of the Invention

[0009] In view of this, in order to solve the problems of insufficient concealment, low visual contrast or the need for complex excitation conditions in existing information encryption materials, the present invention provides a long-wavelength covalent organic framework material with AIE characteristics, its preparation method and application. By post-synthesizing and modifying a COF with a preset structure, a long-wavelength AIE-COF material is efficiently constructed, and it is further prepared into a screen printing functional ink for application in the field of high-security and high-concealment visual information encryption.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A long-wavelength covalent organic framework material with AIE properties has the following structural formula:

[0012] .

[0013] A method for preparing a long-wavelength covalent organic framework material with AIE properties, the synthetic route of which is as follows:

[0014] .

[0015] The steps of a method for preparing a long-wavelength covalent organic framework material with AIE properties are as follows:

[0016] S1. 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 2-hydroxy-1,3,5-benzyltricarboxaldehyde, and an aqueous solution of acetic acid were placed in a Pyrex tube containing solvent and subjected to sonication; then, the mixture was refrigerated and evacuated to obtain MT-HBTA-COF, a covalent organic framework material containing a Schiff base structure.

[0017] S2. The covalent organic framework material MT-HBTA-COF is mixed with styrene in a solvent, and an oxidant and a catalyst are added. After ultrasonic dispersion and freeze-circulation degassing, a long-wavelength covalent organic framework material PM-MT-HBTA-COF with AIE characteristics is obtained.

[0018] Further, step S1 uses 0.2-0.5 mmol of 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 0.1-0.3 mmol of 2-hydroxy-1,3,5-benzenetrialdehyde, 0.1-0.5 mL of aqueous acetic acid solution and 1-5 mL of solvent.

[0019] Furthermore, step S2 uses 30-70 mg of covalent organic framework material MT-BTA-COF, 1-5 mL of styrene, 0.1-0.5 mmol of oxidant 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, 0.01-0.1 mL of catalyst boron trifluoride diethyl ether, and 1-5 mL of solvent.

[0020] Furthermore, the solvent in steps S1 and S2 is any one or a combination of two or more of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, dioxane, mesitylene, n-butanol, o-dichlorobenzene, and toluene.

[0021] Furthermore, in steps S1 and S2, the patient is sonicated for 10-30 minutes, subjected to cryogenic cycles and evacuation 3-9 times, and reacted at 50-150℃ for 3-8 days.

[0022] The above method produces long-wavelength covalent organic framework materials with AIE properties.

[0023] The aforementioned long-wavelength covalent organic framework materials with AIE properties are used as functional inks in screen printing.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. This invention employs a two-step synthesis method and a post-synthetic modification strategy. First, MT-HBTA-COF, a covalent organic framework material with an ordered porous structure, is constructed via a Schiff base reaction using 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl and 2-hydroxy-1,3,5-benzenetriformaldehyde in an aqueous acetic acid solution as a catalyst. The synthetic route is well-defined, the reaction conditions are mild, and the material exhibits good crystallinity and stability. Further, using MT-HBTA-COF as a precursor, styrene is used for post-synthetic modification with styrene under the action of an oxidant and catalyst, successfully introducing styrene groups into the framework structure to obtain PM-MT-HBTA-COF, a covalent organic framework material with long-wavelength AIE characteristics.

[0026] 2. This invention successfully introduces styrene groups into the COF framework through a post-synthetic modification strategy, effectively controlling the photophysical properties of the material and inducing long-wavelength aggregation-induced emission. The material exhibits strong fluorescence emission in the solid state, with a significant redshift in emission wavelength. The fluorescence quantum yield of this material in the aggregated state can reach 6.58%, and the maximum emission wavelength redshifts from 657 nm before modification to 724 nm, demonstrating excellent solid-state luminescence performance and long-wavelength emission characteristics.

[0027] 3. The long-wavelength AIE-COF material prepared by this invention is highly compatible with aqueous media. It can be easily formulated into high-performance screen printing ink. The printed pattern has a high degree of visual integration with common dark substrates under natural light, achieving perfect information concealment. Under 365nm ultraviolet light excitation, the pattern instantly presents deep red fluorescence, with rapid decryption response and significant contrast, making it suitable for information encryption and anti-counterfeiting fields. Attached Figure Description

[0028] Figure 1 The structure and characterization diagram of the COFs material prepared in Example 1 of this invention are shown below;

[0029] Among them, (a) is the structural diagram of MT-HBTA-COF;

[0030] (b) Comparison of simulated PXRD plots and experimental data for different stacking modes of MT-HBTA-COF;

[0031] (c) Pawley refinement of the PXRD plot of MT-HBTA-COF;

[0032] (d) is the structure diagram of PM-MT-HBTA-COF;

[0033] (e) Comparison between simulated PXRD plots and experimental data for different stacking modes of PM-MT-HBTA-COF;

[0034] (f) Pawley refinement of the PXRD plot of PM-MT-HBTA-COF;

[0035] (g) is a comparison of PXRD patterns of PM-MT-HBTA-COF and MT-HBTA-COF;

[0036] (h) shows the FT-IR plots of PM-MT-HBTA-COF and MT-HBTA-COF;

[0037] (i) shows the thermogravimetric curves of PM-MT-HBTA-COF and MT-HBTA-COF.

[0038] Figure 2 The fluorescence performance diagram of the COFs material prepared in Example 1 of this invention is shown.

[0039] Among them, (a) is the excitation emission spectrum of MT-HBTA-COF;

[0040] (b) The fluorescence spectra of PM-MT-HBTA-COF in DCM / THF mixed solvents with different ratios;

[0041] Figure 2 (c) shows the fluorescence lifetime curve of MT-HBTA-COF;

[0042] (d) shows the excitation emission spectrum of PM-MT-HBTA-COF;

[0043] (e) shows the fluorescence spectra of PM-MT-HBTA-COF in DCM / THF mixed solvents with different ratios;

[0044] (f) shows the fluorescence lifetime curve of MT-HBTA-COF.

[0045] Figure 3 The images show the preparation and anti-counterfeiting encryption of PM-MT-HBTA-COF, a long-wavelength covalent organic framework material with AIE properties prepared in Example 1 of this invention, as a functional ink in screen printing. Detailed Implementation

[0046] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0047] The present invention relates to a long-wavelength covalent organic framework material with AIE properties, the structural formula of which is:

[0048] .

[0049] Its synthetic route is as follows:

[0050] .

[0051] Example 1

[0052] A method for preparing a long-wavelength covalent organic framework material with AIE properties includes the following steps:

[0053] S1. Place 0.3 mmol of 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 0.2 mmol of 2-hydroxy-1,3,5-benzenetrialdehyde, and 0.3 mL of aqueous acetic acid in a 10 mL Pyrex tube containing 3 mL of solvent (N,N-dimethylformamide) and sonicate for 10 min to disperse the system; then evacuate the system three times by freezing and evacuating, and react at 120 °C for 3 days.

[0054] The mixture of products from the first step was washed three times each with 1,4-dioxane, acetone, and tetrahydrofuran, and then dried in a vacuum oven for 12 hours to obtain the covalent organic framework material MT-BTA-COF, with a yield of approximately 90%.

[0055] S2. Using 50 mg of MT-HBTA-COF as the starting material, it was mixed with 2 mL of styrene in 3 mL of N,N-dimethylformamide, and 0.12 mmol of oxidant 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and 0.042 mL of catalyst boron trifluoride diethyl ether were added. The mixture was also ultrasonically dispersed for 10 min, evacuated by freezing cycle 3 times, and sealed and reacted at 80 °C for 3 days.

[0056] The product mixture from the second step was washed three times each with tetrahydrofuran, deionized water, and ethanol, and then dried in a vacuum oven for 12 hours to obtain PM-MT-HBTA-COF, an organic framework structure material with long wavelength AIE characteristics, with a yield of approximately 56%.

[0057] Figure 1 The diagram shows the structure and characterization of the COFs material prepared in Example 1 of this invention. The structures of MT-HBTA-COF and PM-MT-HBTA-COF are shown below. Figure 1 As shown in (a) and (d), the COF structure was simulated using Materials Studio. XRD patterns were simulated for the theoretical crystal models under different possible stacking modes. The results are shown in [Figure 1]. Figure 1 (b) Comparison between simulated PXRD patterns and experimental data of different stacking modes of MT-HBTA-COF; (e) Comparison between simulated PXRD patterns and experimental data of different stacking modes of PM-MT-HBTA-COF. The micro-geometric configuration of modified COFs materials was explored in depth, and the PXRD patterns of the simulated structures were obtained. The comparison with the experimental PXRD patterns showed that the PXRD patterns of the AA stacked structure were basically consistent with those of the experimental structure.

[0058] Based on the Bragg theory and AA stacked crystal structure of the synthesized COFs, Pawley refinement was performed on the XRD data of the COFs using MS software. The results are shown in [Figure number missing]. Figure 1 (c) Pawley refinement of the PXRD plot of MT-HBTA-COF; (f) Pawley refinement of the PXRD plot of MT-HBTA-COF. The refined simulated XRD curves are in good agreement with the experimentally measured PXRD curves, with only minor deviations, indicating that this method can synthesize AA-stacked COF models.

[0059] The PXRD pattern of PM-MT-HBTA-COF obtained after post-synthetic modification was compared with that of the original imine-linked precursor COFs. The results are shown in [Figure number missing]. Figure 1 (g) PXRD comparison of PM-MT-HBTA-COF and MT-HBTA-COF: the diffraction peak positions remain unchanged, but the intensity is significantly enhanced, the full width at half maximum (FWHM) of the peaks is correspondingly narrowed, and the peak shape is sharper. The crystallinity and long-range order of the material are improved after modification.

[0060] The bonding structure of COF materials was studied using Fourier transform infrared spectroscopy (FT-IR), and the results are shown in [Figure number missing]. Figure 1 (h) The FT-IR spectra of PM-MT-HBTA-COF and MT-HBTA-COF show a characteristic absorption peak at 1615 cm⁻¹, attributed to the C=N stretching vibration in quinoline. This signal confirms the formation of the quinoline structure during the reaction. Simultaneously, the intensity of the C=N stretching vibration peak in the original imine bond characteristic region (1628 cm⁻¹) is significantly reduced, indicating that the original imine bond was effectively reduced or transformed during the reaction, demonstrating the successful conversion of the imine to quinoline bond during the post-modification process.

[0061] Thermogravimetric analysis was performed on the sample by heating it from room temperature to 800℃ at a heating rate of 10℃ / min under an argon atmosphere. The results are shown in [Figure number missing]. Figure 1 (i) Thermogravimetric curves of PM-MT-HBTA-COF and MT-HBTA-COF. After post-synthetic modification, PM-MT-HBTA-COF exhibits a similar thermal decomposition initiation temperature to its precursor COF material MT-HBTA-COF, indicating that the basic framework structure of the material maintains high stability after chemical modification. Furthermore, at the high-temperature stage (800℃), the final residual mass of PM-MT-HBTA-COF is higher than that of the corresponding precursor COF material MT-HBTA-COF, further confirming the introduction of the quinoline structural unit and indicating that the formation of the quinoline structure further enhances the thermal stability of the covalent organic framework.

[0062] Figure 2The fluorescence performance of the COFs material prepared in Example 1 of this invention is shown in the figure. The fluorescence spectrum results in the room temperature solid powder state are shown below. Figure 2 (a) Excitation and emission spectrum of MT-HBTA-COF; (d) Excitation and emission spectrum of PM-MT-HBTA-COF. The precursor COF material MT-HBTA-COF exhibits the best fluorescence response under excitation at a wavelength of 469 nm, with its maximum emission peak located at 656 nm. Material 2, obtained after post-synthesis modification, shows significant changes in optical properties. Its optimal excitation wavelength is red-shifted to 470 nm, and its maximum emission wavelength is further red-shifted to 724 nm, exhibiting typical long-wavelength luminescence characteristics.

[0063] Strong red emission was observed in MT-HBTA-COF and PM-MT-HBTA-COF in THF or DCM / THF mixed solvents, as shown in the figure. Figure 2 (b) Fluorescence spectra of MT-HBTA-COF in DCM / THF mixed solvents with different proportions; (e) Fluorescence spectra of PM-MT-HBTA-COF in DCM / THF mixed solvents with different proportions. As the volume fraction of the undesirable solvent DCM increases, the system gradually changes from a molecularly dispersed state to an aggregated state. It is observed that the PL intensity increases sharply and the emission wavelength is slightly red-shifted, indicating that the synthesized COFs material exhibits AIE characteristics.

[0064] Fluorescence lifetime analysis was performed using a second-order exponential fitting method at the optimal excitation wavelength. The results are shown in [Figure number missing]. Figure 2 (c) Fluorescence lifetime curves of MT-BTA-COF; (f) Fluorescence lifetime curves of PM-MT-HBTA-COF. The calculated fluorescence lifetimes of MT-HBTA-COF and PM-MT-HBTA-COF are 1.03 ns and 0.42 ns, respectively. This indicates that the introduction of the quinoline structure not only effectively modulates the excited-state relaxation process of the material and significantly improves its radiative transition efficiency, but also enhances fluorescence emission.

[0065] like Figure 3 As shown, the long-wavelength covalent organic framework material PM-MT-HBTA-COF with AIE properties prepared in Example 1 of this invention is used as a functional ink for screen printing.

[0066] Example 2

[0067] A method for preparing a long-wavelength covalent organic framework material with AIE properties includes the following steps:

[0068] S1. Place 0.5 mmol of 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 0.3 mmol of 2-hydroxy-1,3,5-benzyltricarboxaldehyde, and 0.5 mL of aqueous acetic acid in a 10 mL Pyrex tube containing 5 mL of solvent (dioxane) and sonicate for 20 min; then evacuate the tube six times by freezing and react at 120 °C for 5 days.

[0069] The mixture of products from the first step was washed three times each with acetone, tetrahydrofuran, and methanol, and then dried in a vacuum oven for 12 hours to obtain the covalent organic framework material MT-BTA-COF, with a yield of approximately 80%.

[0070] S2. Using 70 mg of MT-HBTA-COF as the starting material, it was mixed with 5 mL of styrene in 5 mL of dioxane, and 0.5 mmol of oxidant 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and 0.1 mL of catalyst boron trifluoride diethyl ether were added. The mixture was also ultrasonically dispersed for 20 min, evacuated 6 times by freezing, and reacted at 120 °C for 5 days.

[0071] The product mixture from the second step was washed three times each with acetone, toluene, and ethanol, and then dried in a vacuum oven for 12 hours to obtain PM-MT-HBTA-COF, an organic framework structure material with long wavelength AIE characteristics, with a yield of approximately 43%.

[0072] Example 3

[0073] A method for preparing a long-wavelength covalent organic framework material with AIE properties includes the following steps:

[0074] S1. Place 0.2 mmol of 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 0.3 mmol of 2-hydroxy-1,3,5-benzenetrialdehyde, and 0.2 mL of aqueous acetic acid in a 10 mL Plyrex tube containing 2 mL of solvent (o-dichlorobenzene) and sonicate for 30 min; then evacuate the tube three times by freezing and react at 150 °C for 6 days.

[0075] The mixture of products from the first step was washed three times each with 1,4-dioxane, acetone, and tetrahydrofuran, and then dried in a vacuum oven for 12 hours to covalently obtain the organic framework structure material MT-BTA-COF, with a yield of approximately 77%.

[0076] S2. Using 30-70 mg of MT-HBTA-COF as the starting material, it was mixed with 2 mL of styrene in 2 mL of o-dichlorobenzene, and 0.3 mmol of oxidant 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and 0.05 mL of catalyst boron trifluoride diethyl ether were added. The mixture was also ultrasonically dispersed for 30 min, evacuated by freezing 3 times, and reacted at 150 °C for 6 days.

[0077] The product mixture from the second step was washed three times each with tetrahydrofuran, deionized water, and ethanol, and then dried in a vacuum oven for 12 hours to obtain PM-MT-HBTA-COF, an organic framework structure material with long wavelength AIE characteristics, with a yield of approximately 50%.

[0078] Example 4

[0079] A method for preparing a long-wavelength covalent organic framework material with AIE properties includes the following steps:

[0080] S1. Place 0.2 mmol of 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 0.1 mmol of 2-hydroxy-1,3,5-benzenetrialdehyde, and 0.1 mL of aqueous acetic acid into a 10 mL Pyrex tube containing 1 mL of acetonitrile, and sonicate for 20 min; then evacuate the tube five times by freezing and react at 50 °C for 3 days.

[0081] The mixture of products from the first step was washed three times each with acetone, tetrahydrofuran, and methanol, and then dried in a vacuum oven for 12 hours to obtain the covalent organic framework material MT-BTA-COF, with a yield of approximately 70%.

[0082] S2. Using 30 mg of MT-HBTA-COF as the starting material, it was mixed with 1 mL of styrene in 1 mL of acetonitrile, and 0.1 mmol of oxidant 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and 0.01 mL of catalyst boron trifluoride diethyl ether were added. The mixture was also ultrasonically dispersed for 10-30 min, evacuated 5 times by freezing cycle, and reacted at 50 °C for 3 days.

[0083] The product mixture from the second step was washed three times each with acetone, toluene, and ethanol, and then dried in a vacuum oven for 12 hours to obtain PM-MT-HBTA-COF, an organic framework structure material with long wavelength AIE characteristics, with a yield of approximately 40%.

[0084] Example 5

[0085] A method for preparing a long-wavelength covalent organic framework material with AIE properties includes the following steps:

[0086] S1. Place 0.5 mmol of 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 0.3 mmol of 2-hydroxy-1,3,5-benzenetrialdehyde, and 0.5 mL of aqueous acetic acid into a 10 mL Plyrex tube containing 5 mL of solvent (n-butanol and o-dichlorobenzene) and sonicate for 30 min; then evacuate the tube nine times by freezing and react at 130 °C for 7 days.

[0087] The mixture of products from the first step was washed three times each with acetone, tetrahydrofuran, and methanol, and then dried in a vacuum oven for 12 hours to obtain the covalent organic framework material MT-BTA-COF, with a yield of approximately 65%.

[0088] S2. Using 70 mg of MT-HBTA-COF as the starting material, it was mixed with 5 mL of styrene in 5 mL of solvent (n-butanol, o-dichlorobenzene), and 0.5 mmol of oxidant 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and 0.1 mL of catalyst boron trifluoride diethyl ether were added. The mixture was also ultrasonically dispersed for 30 min, evacuated 9 times by freezing cycle, and reacted at 130 °C for 7 days.

[0089] The product mixture from the second step was washed three times each with acetone, toluene, and ethanol, and then dried in a vacuum oven for 12 hours to obtain PM-MT-HBTA-COF, an organic framework structure material with long wavelength AIE characteristics, with a yield of approximately 35%.

[0090] Example 6

[0091] A method for preparing a long-wavelength covalent organic framework material with AIE properties includes the following steps:

[0092] S1. Place 0.3 mmol of 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 0.2 mmol of 2-hydroxy-1,3,5-benzyltricarboxaldehyde, and 0.4 mL of aqueous acetic acid solution into a 10 mL Pyrex tube containing 4 mL of toluene and sonicate for 20 min; then evacuate the tube four times by freezing and react at 70 °C for four days.

[0093] The mixture of products from the first step was washed three times each with acetone, tetrahydrofuran, and methanol, and then dried in a vacuum oven for 12 hours to obtain the covalent organic framework material MT-BTA-COF, with a yield of approximately 60%.

[0094] S2. Using 60 mg of MT-HBTA-COF as the starting material, it was mixed with 3 mL of styrene in 3 mL of toluene, and 0.2 mmol of oxidant 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and 0.06 mL of catalyst boron trifluoride diethyl ether were added. The mixture was also ultrasonically dispersed for 20 min, evacuated by freezing cycle 4 times, and reacted at 70 °C for 4 days.

[0095] The product mixture from the second step was washed three times each with acetone, toluene, and ethanol, and then dried in a vacuum oven for 12 hours to obtain PM-MT-HBTA-COF, an organic framework structure material with long wavelength AIE characteristics, with a yield of approximately 30%.

[0096] The above-described embodiment 1 is the preferred embodiment of the present invention.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A covalent organic framework material with long-wavelength AIE properties, characterized in that, The structural formula is: 。 2. The method for preparing a long-wavelength covalent organic framework material with AIE characteristics according to claim 1, characterized in that, Its synthetic route is as follows: 。 3. The method for preparing a long-wavelength covalent organic framework material with AIE characteristics according to claim 2, characterized in that, The steps are as follows: S1. 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 2-hydroxy-1,3,5-benzyltricarboxaldehyde, and an aqueous solution of acetic acid were placed in a Pyrex tube containing solvent and subjected to sonication; then, the mixture was refrigerated and evacuated to obtain MT-HBTA-COF, a covalent organic framework material containing a Schiff base structure. S2. The covalent organic framework material MT-HBTA-COF is mixed with styrene in a solvent, and an oxidant and a catalyst are added. After ultrasonic dispersion and freeze-circulation degassing, a long-wavelength covalent organic framework material PM-MT-HBTA-COF with AIE characteristics is obtained.

4. The method for preparing a long-wavelength covalent organic framework material with AIE characteristics according to claim 3, characterized in that, Step S1 uses 0.2-0.5 mmol of 4,4'-diamino-2,2'-dimethyl-1,1'-biphenyl, 0.1-0.3 mmol of 2-hydroxy-1,3,5-benzenetrialdehyde, 0.1-0.5 mL of aqueous acetic acid solution, and 1-5 mL of solvent.

5. The method for preparing a long-wavelength covalent organic framework material with AIE characteristics according to claim 3, characterized in that, Step S2 uses 30-70 mg of covalent organic framework material MT-BTA-COF, 1-5 mL of styrene, 0.1-0.5 mmol of oxidant 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, 0.01-0.1 mL of catalyst boron trifluoride diethyl ether, and 1-5 mL of solvent.

6. A method for preparing a long-wavelength covalent organic framework material with AIE characteristics according to claim 4 or 5, characterized in that, The solvents in steps S1 and S2 are any one or a combination of two or more of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, dioxane, mesitylene, n-butanol, o-dichlorobenzene, and toluene.

7. The method for preparing a long-wavelength covalent organic framework material with AIE characteristics according to claim 6, characterized in that, In steps S1 and S2, the patient is sonicated for 10-30 minutes, subjected to 3-9 cycles of cryogenic evacuation, and reacted at 50-150°C for 3-8 days.

8. A long-wavelength covalent organic framework material with AIE properties prepared by the method according to claim 3.

9. The application of the long-wavelength covalent organic framework material with AIE properties as described in claim 8 as a functional ink in screen printing.

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