Stimuli-responsive luminescent three-dimensional covalent organic framework material and preparation method and application thereof

Abstract

The application discloses a stimulus-responsive luminescent three-dimensional covalent organic framework material and a preparation method and application thereof, and belongs to the technical field of organic photoelectric materials. The material is prepared by condensation reaction of a DPAC aldehyde group containing vibration-induced emission active building unit and a tetrahedral amino monomer, and has an ordered three-dimensional crystal structure. While the material maintains the framework crystallinity and stability, the conformational adjustment ability of the DPAC unit is retained, so that the luminescence behavior of the material can change with the change of a solvent environment, a viscosity and external pressure, and the change is represented as adjustable response of emission intensity, emission wavelength and / or luminescence color. Therefore, the material can be used as a stimulus-responsive fluorescent material for environment identification, viscosity monitoring and pressure detection.

Description

Technical Field

[0001] This invention belongs to the field of organic optoelectronic materials technology, specifically relating to stimulus-responsive luminescent three-dimensional covalent organic framework materials, their preparation methods, and applications. Background Technology

[0002] Covalent organic frameworks (COFs) are a class of crystalline porous materials formed by organic structural units linked by covalent bonds. They possess characteristics such as designable structure, tunable pore environment, modifiable framework composition, and periodic arrangement of functional units. In recent years, COFs have shown broad application prospects in fields such as gas adsorption and separation, chemical sensing, optoelectronic functional materials, catalysis, energy storage, and smart response materials. Since the structure and performance of COFs are highly dependent on their building blocks, designing and introducing functional units with specific photophysical properties and dynamic response capabilities is a key approach to expanding the application of COFs in stimulus-responsive luminescence.

[0003] Stimulus-responsive fluorescent materials can achieve visual response detection by changes in emission intensity, emission wavelength, or emission color under external stimuli. Factors such as solvent environment, viscosity changes, and external pressure can all affect the conformation of luminescent molecules, intermolecular interactions, and non-radiative decay processes, thus leading to changes in the fluorescence signal. Therefore, developing luminescent materials that can sensitively respond to a variety of stimuli is of great significance for constructing intelligent sensing materials and studying structure-luminescence relationships.

[0004] On the other hand, vibrational induced emission (VIE) provides a new approach for constructing dynamically tunable luminescent materials. Typical VIE-active molecules, such as dihydrodibenzo[a,c]phenazine (DPAC) and its derivatives, typically exhibit a bent conformation in the ground state. In the excited state, they undergo a conformational transition from bent to planar, resulting in significant Stokes shifts, dual emission, and tunable emission colors. Because the excited-state conformational evolution of these molecules is highly sensitive to the surrounding microenvironment, their luminescence behavior can be modulated by factors such as solvent polarity, aggregation state, viscosity, and pressure. Therefore, introducing VIE active units into an ordered COF framework holds promise for combining dynamic conformational changes with a crystalline porous framework, enabling the construction of tunable luminescent materials with solvent, viscosity, and pressure responsiveness.

[0005] Currently, there are some reports on stimulus-responsive luminescent materials based on carbon-free polymer (COF). For example, dynamic response units such as spiropyran, azobenzene, and molecular motors have been introduced into the COF framework, and photoresponse modulation is achieved through photoisomerization, ring-opening / ring-closing reactions, or intramolecular rotation. These studies show that introducing dynamic molecular motion or structural transformation into an ordered framework is an effective strategy for constructing stimulus-responsive COFs. However, existing stimulus-responsive COFs are mostly concentrated in photoresponsive or single-stimulus-responsive systems, and COF materials that can achieve multi-mode tunable luminescence responses in terms of solvent, viscosity, and pressure through excited-state conformational changes are still relatively few.

[0006] The existing technology has the following characteristics:

[0007] (1) Most of the reported luminescent COFs are constructed using traditional rigid luminescent units or AIE active groups. Their luminescence regulation mainly depends on intramolecular rotation restriction, aggregation-induced luminescence, or changes in electronic structure. However, there is still a lack of COF materials based on the VIE mechanism, especially those that utilize the conformational transition from excited state to "bending to planarization" to achieve tunable luminescence response.

[0008] (2) Although traditional rigid planar light-emitting units have good structural stability and electronic structure tunability, their conformational adaptability is insufficient. They are difficult to produce obvious dynamic conformational changes under external stimuli such as solvent, viscosity and pressure, thus limiting their light-emitting response range and sensitive control capability.

[0009] (3) Although VIE active molecules have been used in small molecules, supramolecular systems, gels, polymers and host-guest systems, it remains an important challenge to retain sufficient conformational freedom of VIE units while maintaining the crystallinity and structural stability of the framework after introducing them into the ordered crystalline COF framework.

[0010] (4) Existing stimulus-responsive luminescent COFs still need further development in multi-mode detection. In particular, there are still few three-dimensional COF materials that can simultaneously produce tunable fluorescence responses to solvent environment, viscosity changes and external pressure, and exhibit changes in emission intensity, emission wavelength or luminescence color.

[0011] (5) In the existing system, the relationship between external stimuli and changes in framework structure, conformational evolution of light-emitting units and photophysical response is still not clear enough, making it difficult to reveal the regulatory mechanism of the crystalline framework environment on dynamic light-emitting units at the molecular level.

[0012] Therefore, developing a stimulus-responsive luminescent three-dimensional covalent organic framework material containing VIE active units, which can maintain good crystallinity and structural stability while retaining the conformational adjustment capability of dynamic luminescent units and generate tunable fluorescence responses to external stimuli such as solvents, viscosity and pressure, is of great significance for expanding the application of COF in intelligent luminescence detection and stimulus-responsive materials. Summary of the Invention

[0013] To address the aforementioned deficiencies in existing technologies, this invention provides a stimulus-responsive luminescent three-dimensional covalent organic framework material, its preparation method, and its applications. Specifically, it provides a luminescent material incorporating vibration-induced emission (VIE) active units into a three-dimensional covalent organic framework, and uses it for fluorescence response detection to external stimuli such as solvent, viscosity, and pressure. This invention constructs a covalent organic framework material with an ordered three-dimensional structure by designing aldehyde building blocks containing DPAC structures and reacting them with tetrahedral amino monomers via condensation. This material maintains the framework's crystallinity and structural stability while retaining the conformational adjustment capability of the DPAC units, allowing its luminescence behavior to change with solvent environment, viscosity variations, and external pressure, exhibiting tunable responses in emission intensity, emission wavelength, and / or emission color. Therefore, this material can serve as a stimulus-responsive fluorescent material for environmental identification, viscosity monitoring, and pressure detection.

[0014] This invention is achieved through the following technical solution:

[0015] In a first aspect, the present invention provides a stimulus-responsive luminescent three-dimensional covalent organic framework material, wherein the material is a three-dimensional covalent organic framework material constructed by dynamic covalent condensation reaction of the following structural units, and has vibration-induced emission characteristics:

[0016] .

[0017] Secondly, this invention provides a method for preparing a stimulus-responsive luminescent three-dimensional covalent organic framework material, comprising the following steps:

[0018] (1) Weigh 2,7-dibromophenanthrene-9,10-dione and aniline, add anhydrous toluene to dissolve, add titanium tetrachloride under low temperature conditions, stir the reaction, and remove the solvent after the reaction is completed; then dissolve the obtained product in a mixed solvent of THF and ethanol, add NaBH4 to carry out the reduction reaction, evaporate and concentrate after the reaction is completed, and wash the residue with ethanol to obtain compound one.

[0019] (2) Take compound one and iodobenzene, add 1,2,4-trichlorobenzene to dissolve, then add K2CO3 and Cu(OTf)2, heat and stir to react; after the reaction is completed, remove the 1,2,4-trichlorobenzene solvent, dilute the residue with water, extract with dichloromethane, combine the organic phases, dry, filter, concentrate, and then purify by column chromatography to obtain compound two;

[0020] (3) Take compound bis, 4-formylphenylboronic acid, K2CO3 and Pd(PPh3)4, add a mixed solvent of THF and water, and react under nitrogen protection. After the reaction is completed, cool to room temperature, dilute with water, and extract with dichloromethane. Combine the organic phases, dry and concentrate, and then purify by column chromatography to obtain compound DPAC-CHO.

[0021] (4) Weigh out compound DPAC-CHO and 1,3,5,7-tetra(4-aminophenyl)adamantane, place them in a Pyrex glass tube, add anhydrous n-butanol and anhydrous o-dichlorobenzene as mixed solvents, and add aqueous acetic acid as catalyst. Freeze, vacuum seal, and then heat to react. After filtering and washing the product, immerse it in anhydrous acetone for solvent replacement. Finally, remove the solvent under vacuum conditions. This is the stimulus-responsive luminescent three-dimensional covalent organic framework material JUC-736.

[0022] Further, in step (1), the ratio of the amount of 2,7-dibromophenanthrene-9,10-dione, aniline, titanium tetrachloride and NaBH4 added is 15.0 mmol: 274 mmol: 36.4 mmol: 52.8 mmol; the reaction temperature for adding titanium tetrachloride is 0 °C, and the stirring reaction time is 24 h; the volume ratio of THF to ethanol in the reduction reaction is 1:1, and the reflux time is 2 h.

[0023] Furthermore, in step (2), the molar ratio of compound 1, iodobenzene, K2CO3 and Cu(OTf)2 is 1.93:3.18:4.3:5.7.

[0024] Furthermore, in step (2), the process conditions for the heating reaction are: reacting at 210℃ for 5h; column chromatography purification uses neutral alumina as the stationary phase and a mixed solvent of petroleum ether and dichloromethane as the eluent, with a volume ratio of 10:1.

[0025] Further, in step (3), the molar ratio of compounds di-, 4-formylphenylboronic acid, Pd(PPh3)4 and K2CO3 is 1.0: 4.5: 0.2: 10.0; the volume ratio of THF and water in the mixed solvent is 30.0: 12.0; the process conditions for the heating reaction are: under nitrogen protection, the reaction is carried out at 80℃ for 3 days; the column chromatography purification uses silica gel as the stationary phase and a mixed solvent of petroleum ether and dichloromethane as the eluent, with a volume ratio of 5:1.

[0026] Further, in step (4), the ratio of the amount of compound DPAC-CHO, 1,3,5,7-tetra(4-aminophenyl)adamantane, anhydrous n-butanol, anhydrous o-dichlorobenzene and 9M acetic acid aqueous solution added is 0.05mmol:0.03mmol:5.46mmol:4.44mmol:0.90mmol; the process conditions for heating reaction are: reaction at 120℃ for 72h; the solvent replacement process is immersion in anhydrous acetone for 8h, and replacement of anhydrous acetone solvent every two hours; finally, drying under vacuum at 60℃.

[0027] Furthermore, in step (4), the Pyrex glass tube has an outer diameter of 10 mm and an inner diameter of 8 mm; the freezing conditions are freezing in a liquid nitrogen bath at 77 K, evacuating to a pressure of 0.15 mmHg inside the tube, and then flame sealing the tube.

[0028] The preparation process of this invention is as follows:

[0029] .

[0030] Thirdly, the present invention also provides the application of stimulus-responsive luminescent three-dimensional covalent organic framework materials, which are used as fluorescent response materials to detect fluorescence response to solvent environment, viscosity changes and external pressure. By monitoring the changes in emission intensity, emission wavelength and / or emission color of the material under different external stimuli, solvent identification, viscosity monitoring and pressure response detection are achieved, as well as for anti-counterfeiting display or optical information storage.

[0031] Compared with the prior art, the advantages of the present invention are as follows:

[0032] (1) Existing stimulus-responsive luminescent COFs mostly rely on traditional mechanisms such as intramolecular charge transfer (ICT), excited-state intramolecular proton transfer (ESIPT), Foster resonance energy transfer (FRET), excimer / exciplex emission, and aggregation-induced emission (AIE) for luminescence regulation. However, this invention introduces DPAC units with vibration-induced emission (VIE) characteristics into the three-dimensional COF framework, which are periodically arranged in an ordered crystalline state and retain the ability to regulate the excited-state conformation, thereby realizing a tunable luminescence response based on the change of excited-state conformation and opening up a new mechanism for COF fluorescence regulation.

[0033] (2) VIE active molecules exhibit a bent conformation in the ground state and can undergo a conformational transition from bent to planar in the excited state. Their luminescence behavior is highly sensitive to external factors such as solvent environment, viscosity, aggregation state, and pressure. However, there are few reports on introducing such dynamic luminescent units into an ordered crystalline COF framework while maintaining the crystallinity and structural stability of the framework. This invention successfully prepared a stimulus-responsive luminescent three-dimensional COF by rationally designing DPAC aldehyde-based building blocks, realizing the combination of dynamic luminescent units and an ordered porous framework.

[0034] (3) The three-dimensional COF obtained in this invention can produce significant fluorescence responses to various external stimuli such as solvent, viscosity and pressure, specifically manifested as changes in emission intensity, emission wavelength and / or emission color. The reason is that the ordered three-dimensional framework provides a specific local microenvironment and conformational constraint for the DPAC unit, so that its excited state conformational evolution process can be regulated by external stimuli, thereby realizing visualized and adjustable fluorescence detection.

[0035] (4) This invention can be used not only for solvent identification, viscosity monitoring and pressure detection, but also provides an effective platform for studying the conformational changes of dynamic light-emitting units in crystalline porous frameworks, framework environment regulation and structure-luminescence relationship, and expands the application of COF in stimulus-responsive light-emitting materials and smart sensing materials. Attached Figure Description

[0036] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0037] Figure 1 Compound 1 prepared in Example 1 1 H NMR spectrum;

[0038] Figure 2 Compound II prepared in Example 1 1 H NMR spectrum;

[0039] Figure 3 DPAC-CHO prepared in Example 1 1 H NMR spectrum;

[0040] Figure 4 Fourier transform infrared spectra of JUC-736 and its monomers prepared in Example 1;

[0041] Figure 5 Powder X-ray diffraction pattern of JUC-736 prepared in Example 1;

[0042] Figure 6 JUC-736 prepared in Example 1 13 C NMR spectrum;

[0043] Figure 7 Thermogravimetric analysis spectrum of JUC-736 prepared in Example 1;

[0044] Figure 8 The nitrogen adsorption-desorption isotherm of JUC-736 prepared in Example 1;

[0045] Figure 9 The pore size distribution diagram of JUC-736 prepared in Example 1;

[0046] Figure 10 A scanning electron microscope image of JUC-736 prepared in Example 1;

[0047] Figure 11 Transmission electron microscopy image of JUC-736 prepared in Example 1;

[0048] Figure 12 The UV-Vis absorption and emission spectra of compounds DPAC-CHO and JUC-736 prepared in Example 1 are shown.

[0049] Figure 13 The emission spectra of JUC-736 prepared in Example 1 in different solvents, with an excitation wavelength of 365 nm;

[0050] Figure 14 Emission spectra of JUC-736 prepared in Example 1 dispersed in THF / water mixed solvents with different water contents;

[0051] Figure 15 The graph shows the CIE variation of JUC-736 prepared in Example 1 dispersed in THF / water mixed solvents with different water contents.

[0052] Figure 16 The viscosity variation of JUC-736 prepared in Example 1 dispersed in different ratios of toluene and polytetrahydrofuran is shown in the graph.

[0053] Figure 17 Emission spectra of JUC-736 prepared in Example 1 under different pressures;

[0054] Figure 18 CIE images and fluorescence images of JUC-736 prepared in Example 1 under different pressures;

[0055] Figure 19 The image shows the spectral changes of JUC-736 prepared in Example 1 during the decompression process. Detailed Implementation

[0056] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0057] In the following embodiments, the specific source of each raw material and reagent is Bailingwei Company;

[0058] Unless otherwise specified, all other raw materials, reagents, or processing techniques are conventional commercially available products or conventional processing techniques in this field.

[0059] Example 1:

[0060] This embodiment provides a stimulus-responsive luminescent three-dimensional covalent organic framework material. The material is a three-dimensional covalent organic framework material constructed from the following structural units through a dynamic covalent condensation reaction, and possesses vibration-induced emission properties:

[0061] .

[0062] This embodiment designs an aldehyde-based COF monomer molecule containing vibrationally induced emission (VIE) active DPAC units, and successfully prepares a highly crystalline, stimulus-responsive three-dimensional covalent organic framework material, named JUC-736, through condensation polymerization with a tetrahedral amino monomer. This three-dimensional COF achieves the periodic arrangement of DPAC luminescent units within an ordered framework, maintaining the framework's crystallinity and structural stability while retaining a certain degree of conformational adjustment capability of the DPAC units. Since DPAC units can undergo a transition from a bent conformation to a planar conformation in the excited state, their luminescence behavior is highly sensitive to the external microenvironment. Therefore, the obtained JUC-736 exhibits significant fluorescence responses under different solvent environments, viscosity changes, and external pressure, specifically manifested as changes in emission intensity, emission wavelength, and / or emission color. This material provides a novel crystalline porous fluorescent response platform for solvent identification, viscosity monitoring, and pressure detection.

[0063] The preparation method of the above-mentioned stimulus-responsive luminescent three-dimensional covalent organic framework material includes the following steps:

[0064] (1) Under stirring, 2,7-dibromophenanthrene-9,10-dione (5.49 g, 15.0 mmol) and aniline (25 mL) were dissolved in anhydrous toluene (170 mL), and titanium tetrachloride (4 mL) was added at 0 °C. After stirring for 24 hours, the original orange solution gradually turned red. The reaction solution was concentrated under reduced pressure, and the result was dissolved in THF / ethanol (1:1, v / v, 100 mL). NaBH4 (2.0 g, 52.8 mmol) was added in portions, and the mixture was refluxed at room temperature for 2 hours. After the reaction was completed, the mixture was concentrated under reduced pressure, and the residue was washed with ethanol (500 mL) to give a white solid of the compound (5.44 g, yield 70%). 1 H NMR (600MHz, CDCl3) δ8.44(d,J=8.8Hz,2H),8.12(d,J=2.0Hz,2H),7.66(dd,J=8. 8,2.0Hz,2H),7.08(dd,J=8.5,7.3Hz,4H),6.82–6.74(m,2H),6.51–6.46(m,4H).

[0065] (2) Compound I (1 g, 1.93 mmol) and iodobenzene (0.65 g, 3.18 mmol) were dissolved in 1,2,4-trichlorobenzene (5 mL), and K2CO3 (0.6 g, 4.3 mmol) and Cu(OTf)2 (0.26 g, 5.7 mmol) were added. The mixture was stirred at 210 °C for 5 hours. Most of the trichlorobenzene was removed by vacuum distillation, giving a black residue. The residue was poured into water (50 mL) and extracted with dichloromethane (3 × 50 mL). The organic phases were combined, dried over anhydrous sodium sulfate, filtered and concentrated, and then purified by column chromatography (neutral alumina, petroleum ether / dichloromethane 10:1) to give compound II as a pale yellow solid (0.78 g, yield 68%). 1 H NMR(600MHz, CDCl3)δ8.42(d,J=8.8Hz,2H),8.17(d,J=2.2Hz,2H),7.73–7.57(m,4H), 7.28(dt,J=7.6,3.8Hz,2H),7.01–6.92(m,4H),6.89–6.80(m,4H),6.81–6.71(m,2H).

[0066] (3) Compound 2 (0.64 g, 1.0 mmol), 4-formylphenylboronic acid (0.68 g, 4.5 mmol), Pd(PPh3)4 (0.23 g, 0.2 mmol), and K2CO3 (1.38 g, 10.0 mmol) were dissolved in THF / H2O (30.0 mL / 12.0 mL). The mixture was heated at 80 °C for 3 days under nitrogen protection. After the reaction was completed, the mixture was cooled to room temperature, diluted with water, and extracted with DCM (300 mL). The organic phases were combined, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crude product was first subjected to rapid column chromatography, and then purified by column chromatography (silica gel, petroleum ether / dichloromethane 5:1) to give DPAC-CHO yellow solid (0.45 g, yield 70%). 1 H NMR (400MHz, CDCl3) δ10.14(s,1H),10.08(s,1H),8.71–8.68(m,2H),8.02–8.00(m,2H),7.70(dd,J=5.8,3.6Hz,2H) ,7.60–7.55(m,6H),7.50–7.47(m,2H),7.31–7.28(m,2H),7.15–7.12(m,4H),6.94–6.88(m,6H),6.75–6.70(m,2H).

[0067] (4) DPAC-CHO (32.2 mg, 0.05 mmol) and 1,3,5,7-tetratetra(4-aminophenyl)adamantane (TAPA, 13 mg, 0.03 mmol) were placed in a 10×8 mm Pyrex tube, and anhydrous n-butanol (0.5 mL), anhydrous o-dichlorobenzene (0.5 mL), and 9M water-soluble acetic acid (0.1 mL) were added. The tube was rapidly frozen to 77 K (liquid nitrogen bath), evacuated to an internal pressure of 0.15 mmHg, and flame-sealed to reduce the tube length to 13 cm. After sealing, the tube was heated at 120 °C for 72 hours to obtain a yellow precipitate. The precipitate was separated by filtration and washed with anhydrous acetone (20 mL). The product was immersed in 20 mL of anhydrous acetone for 8 hours, with the solvent replaced every 2 hours. Then, the product was dried under reduced pressure at 60 °C to obtain a yellow crystalline solid JUC-736 (38.4 mg, 70% yield). Analysis: Cald: C 88.59%; H 5.92%; N 5.49%. Found: C 87.97%; H 6.05%; N 5.42%.

[0068] Figures 1-3 The figures show the 1H NMR spectra of compounds 1, 2, and DPAC-CHO obtained from the above steps. As can be seen from the figures, the characteristic peaks of each product are basically consistent with the corresponding target structures, indicating that the structures of the reaction products in each step are clear, and the target compound DPAC-CHO was successfully obtained.

[0069] Figure 4 The Fourier transform infrared (FT-IR) spectra of compound JUC-736 and its monomers are shown. The blue curve represents the spectrum of the tetrahedral amine monomer TAPA, where the -NH2 stretching vibration peak is located at 3310–3400 cm⁻¹. -1 The gray curve represents the spectrum of the DPAC-CHO monomer, with its aldehyde stretching vibration peak located at 1692 cm⁻¹. -1 The red curve represents the spectrum of the final product JUC-736, at 1624 cm⁻¹. -1 The stretching vibration peak of the imine bond (C=N) can be observed at the point, while the -NH2 peak of TAPA and the aldehyde peak of DPAC-CHO disappear significantly, indicating that the condensation reaction proceeded smoothly and was completed, and the JUC-736 framework structure was successfully constructed.

[0070] Figure 5 The powder X-ray diffraction pattern of the prepared compound JUC-736 is shown. The experimental PXRD pattern of this sample shows characteristic diffraction peaks at 4.11°, 5.83° and 9.21°, indicating that the material has a good ordered pore structure and crystalline characteristics.

[0071] Figure 6 To prepare the compound JUC-736 13 The 1000 C NMR spectrum shows that the NMR peak at 156 ppm confirms the formation of imine bonds.

[0072] Figure 7 The thermogravimetric analysis (TGA) spectra of the synthesized JUC-736 are shown above. The TGA curves under argon atmosphere reveal only a slight mass loss (approximately 3%) below 434 °C, which can be attributed to the evaporation of residual solvent. Significant decomposition begins above 434 °C, resulting in a mass loss of approximately 34%, with the total mass loss reaching approximately 40% by 800 °C. This demonstrates the high thermal stability of the formed JUC-736.

[0073] Figure 8 The figure shows the nitrogen adsorption-desorption curve of the synthesized JUC-736, indicating a good BET of 820m. 2 / g.

[0074] Figure 9 The pore size distribution diagram of the synthesized JUC-736 shows that the covalent organic framework has a uniform pore size of 1.5 nm.

[0075] Figure 10The above-synthesized JUC-736 is shown in a scanning electron microscope image, exhibiting a distinct aggregated micron-sized particle morphology. Overall, the particle surface is not smooth, but rather composed of a large number of densely packed, fine, short rod-shaped nanocrystals, forming a rough surface structure resembling "burrs" or "flower clusters".

[0076] Figure 11 The image above is a transmission electron microscope (TEM) image of the synthesized JUC-736, which, consistent with the SEM image, shows a rod-shaped morphology.

[0077] Figure 12 The images show the UV absorption and photoluminescence spectra of compounds DPAC-CHO and JUC-736. It can be seen that the maximum absorption peaks of both compounds DPAC-CHO and JUC-736 are at 389 nm; the maximum emission wavelengths of compounds DPAC-CHO and JUC-736 are 494 nm and 605 nm, respectively.

[0078] Figure 13 The images show the spectra of JUC-736 in cyclohexane, toluene, and ethyl acetate, with an excitation wavelength of 365 nm. In cyclohexane and toluene, JUC-736 exhibits only long-wavelength emission bands located at approximately 639–653 nm, indicating that planar emission states dominate in these frameworks. However, in ethyl acetate, JUC-736 shows dual emission bands at 450 and 623 nm, indicating the coexistence of curved and planar emission states.

[0079] Figure 14 The aggregated state characteristics of JUC-736 in a mixture of THF and water are shown. When dispersed in THF, JUC-736 mainly exhibits an orange-red emission peak at approximately 618 nm, while the blue emission at approximately 462 nm is almost negligible. As the water content increases from 0% to 40%, the long-wavelength emission intensity of JUC-736 slightly increases, which can be attributed to a reduction in non-radiative transitions and is related to the VIE mechanism. In contrast, the short-wavelength emission of JUC-736 at 463 nm is significantly enhanced. When the water content exceeds 40%, the short-wavelength emission of JUC-736 changes only slightly, while the orange-red emission is significantly enhanced.

[0080] Figure 15 The graph shows the CIE variation of JUC-736 dispersed in different proportions of tetrahydrofuran-water; due to the rapid increase in emission intensity at longer wavelengths, I... blue / I red The ratio gradually decreases and approaches 1, indicating that the emission of blue and red light gradually reaches a balance, thus causing the emission color to evolve towards the near-white light region, with CIE coordinates of (0.33, 0.35).

[0081] Figure 16The photoluminescence spectra of JUC-736 dispersed in toluene and mixed solutions of polytetrahydrofuran (polyTHF) with varying concentrations are presented. As the polyTHF content increases from 0% to 30%, the fluorescence intensity significantly increases; when the polyTHF content is 40–60%, the fluorescence intensity begins to decrease, and the peak position shifts slightly; in the high concentration range (70–90%), the fluorescence intensity continues to weaken, and the peak position remains around 600 nm.

[0082] Figure 17 The photoluminescence (PL) spectrum of JUC-736 under different pressures is shown to be a law of change with pressure. In the low pressure region (0–1 GPa), the emission intensity and peak position of JUC-736 change little. As the pressure increases to about 3 GPa, the emission intensity gradually decreases. Under high pressure, the emission peak redshifts significantly and the intensity weakens, with the maximum wavelength redshift being about 75 nm (8.2 GPa).

[0083] Figure 18 The images show the fluorescence of JUC-736 under different pressures and its CIE chromaticity coordinates. As the pressure increases, the fluorescence of JUC-736 gradually changes from yellow to orange and then to red, exhibiting a multi-color tunable pressure-induced fluorescence response.

[0084] Figure 19 The image shows the spectral changes of JUC-736 during the depressurization process. When JUC-736 is depressurized to 0 GPa, both the emission wavelength and intensity return to their initial state, demonstrating excellent reversibility.

[0085] Comparative Example 1:

[0086] It is basically the same as Example 1, except that in step (4), 9M acetic acid is replaced with 6M acetic acid.

[0087] Comparative Example 2:

[0088] Compared with Example 1, it is basically the same, except that in step (4), the mixed solvent of n-butanol and anhydrous o-dichlorobenzene is replaced with mesitylene and 1,4-dioxane.

[0089] Comparative Example 3:

[0090] Compared with Example 1, it is basically the same, except that the freezing and vacuuming process is omitted in step (4).

[0091] Comparative Example 4:

[0092] It is basically the same as Example 1, except that in step (4), the temperature of the heating reaction is changed to 110°C.

[0093] Comparative Examples 1-4 modified the acid concentration, solvent system, degassing treatment, and reaction temperature in step (4). Compared with Example 1, the changes in the above conditions all affected the nucleation and crystal growth process of JUC-736, reducing the crystallinity and structural order of the resulting product. This indicates that the acid concentration, mixed solvent, freezing and vacuum treatment, and reaction temperature used in Example 1 are more conducive to the formation of the target JUC-736 framework.

[0094] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0095] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0096] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A stimulus-responsive luminescent three-dimensional covalent organic framework material, characterized in that, The material is a three-dimensional covalent organic framework material constructed from the following structural units through a dynamic covalent condensation reaction, and it possesses vibration-induced emission properties: ； The stimulus-responsive luminescent three-dimensional covalent organic framework material is prepared by the following method, including the following steps: (1) Weigh 2,7-dibromophenanthrene-9,10-dione and aniline, add anhydrous toluene to dissolve, add titanium tetrachloride under low temperature conditions, stir to react, remove the solvent after the reaction is completed, the reaction temperature of adding titanium tetrachloride is 0℃; then dissolve the obtained product in a mixed solvent of THF and ethanol, add NaBH4 to carry out reduction reaction, evaporate and concentrate after the reaction is completed, wash the residue with ethanol to obtain compound one; (2) Take compound one and iodobenzene, add 1,2,4-trichlorobenzene to dissolve, then add K2CO3 and Cu(OTf)2, heat and stir to react; after the reaction is completed, remove the 1,2,4-trichlorobenzene solvent, dilute the residue with water, extract with dichloromethane, combine the organic phases, dry, filter, concentrate, and then purify by column chromatography to obtain compound two; (3) Take compound II, 4-formylphenylboronic acid, K2CO3 and Pd(PPh3)4, add a mixed solvent of THF and water, and react under nitrogen protection. After the reaction is completed, cool to room temperature, dilute with water, and extract with dichloromethane. Combine the organic phases, dry and concentrate, and then purify by column chromatography to obtain compound III, namely DPAC-CHO. (4) Weigh out compounds tris and 1,3,5,7-tetra(4-aminophenyl)adamantane, place them in a Pyrex glass tube, add anhydrous n-butanol and anhydrous o-dichlorobenzene as mixed solvents, and add 9M acetic acid aqueous solution as catalyst. Freeze, vacuum seal, and then heat to 120°C to react. After filtering and washing the product, immerse it in anhydrous acetone for solvent replacement. Finally, remove the solvent under vacuum conditions, which is the stimulus-responsive luminescent three-dimensional covalent organic framework material JUC-736.

2. The method for preparing the stimulus-responsive luminescent three-dimensional covalent organic framework material as described in claim 1, characterized in that, Includes the following steps: (1) Weigh 2,7-dibromophenanthrene-9,10-dione and aniline, add anhydrous toluene to dissolve, add titanium tetrachloride under low temperature conditions, stir the reaction, remove the solvent after the reaction is completed, the reaction temperature of adding titanium tetrachloride is 0℃; then dissolve the obtained product in a mixed solvent of THF and ethanol, add NaBH4 to carry out the reduction reaction, evaporate and concentrate after the reaction is completed, wash the residue with ethanol to obtain compound one; (2) Take compound one and iodobenzene, add 1,2,4-trichlorobenzene to dissolve, then add K2CO3 and Cu(OTf)2, heat and stir to react; after the reaction is completed, remove the 1,2,4-trichlorobenzene solvent, dilute the residue with water, extract with dichloromethane, combine the organic phases, dry, filter, concentrate, and then purify by column chromatography to obtain compound two; (3) Take compound bis, 4-formylphenylboronic acid, K2CO3 and Pd(PPh3)4, add a mixed solvent of THF and water, and react under nitrogen protection. After the reaction is completed, cool to room temperature, dilute with water, and extract with dichloromethane. Combine the organic phases, dry and concentrate, and then purify by column chromatography to obtain compound DPAC-CHO. (4) Weigh out compound DPAC-CHO and 1,3,5,7-tetra(4-aminophenyl)adamantane, place them in a Pyrex glass tube, add anhydrous n-butanol and anhydrous o-dichlorobenzene as mixed solvents, and add 9M acetic acid aqueous solution as catalyst. Freeze, vacuum seal, and then heat to 120°C to react. After filtering and washing the product, immerse it in anhydrous acetone for solvent replacement. Finally, remove the solvent under vacuum conditions, which is the stimulus-responsive luminescent three-dimensional covalent organic framework material JUC-736.

3. The method for preparing the stimulus-responsive luminescent three-dimensional covalent organic framework material as described in claim 2, characterized in that, In step (1), the ratio of the amount of 2,7-dibromophenanthrene-9,10-dione, aniline, titanium tetrachloride and NaBH4 added is 15.0 mmol: 274 mmol: 36.4 mmol: 52.8 mmol; the stirring reaction time is 24 h; the volume ratio of THF and ethanol in the reduction reaction is 1:1, and the reflux time is 2 h.

4. The method for preparing the stimulus-responsive luminescent three-dimensional covalent organic framework material as described in claim 2, characterized in that, In step (2), the molar ratio of compound 1, iodobenzene, K2CO3 and Cu(OTf)2 is 1.93:3.18:4.3:5.

7.

5. The method for preparing the stimulus-responsive luminescent three-dimensional covalent organic framework material as described in claim 2, characterized in that, In step (2), the process conditions for the heating reaction are: reacting at 210℃ for 5h; column chromatography purification uses neutral alumina as the stationary phase and a mixed solvent of petroleum ether and dichloromethane as the eluent, with a volume ratio of 10:

1.

6. The method for preparing the stimulus-responsive luminescent three-dimensional covalent organic framework material as described in claim 2, characterized in that, In step (3), the molar ratio of compound di, 4-formylphenylboronic acid, Pd(PPh3)4 and K2CO3 is 1.0:4.5:0.2:10.0; the volume ratio of THF and water in the mixed solvent is 30.0:12.0; the process conditions for the heating reaction are: under nitrogen protection, the reaction is carried out at 80℃ for 3 days; the column chromatography purification uses silica gel as the stationary phase and a mixed solvent of petroleum ether and dichloromethane as the eluent, with a volume ratio of 5:

1.

7. The method for preparing the stimulus-responsive luminescent three-dimensional covalent organic framework material as described in claim 2, characterized in that, In step (4), the ratio of the amount of compound DPAC-CHO, 1,3,5,7-tetra(4-aminophenyl)adamantane, anhydrous n-butanol, anhydrous o-dichlorobenzene and 9M acetic acid aqueous solution added is 0.05mmol:0.03mmol:5.46mmol:4.44mmol:0.90mmol; the process conditions for heating reaction are: reaction at 120℃ for 72h; the solvent replacement process is immersion in anhydrous acetone for 8h, and replacement of anhydrous acetone solvent every two hours; finally, drying under vacuum at 60℃.

8. The method for preparing the stimulus-responsive luminescent three-dimensional covalent organic framework material as described in claim 2, characterized in that, In step (4), the Pyrex glass tube has an outer diameter of 10 mm and an inner diameter of 8 mm. The freezing conditions are freezing in a liquid nitrogen bath at 77 K, evacuating the tube to a pressure of 0.15 mmHg, and then sealing the tube with a flame.

9. The application of the stimulus-responsive luminescent three-dimensional covalent organic framework material as described in claim 1, characterized in that, Specifically, the stimulus-responsive luminescent three-dimensional covalent organic framework material is used as a fluorescent response material to detect fluorescence response to solvent environment, viscosity changes and external pressure. By monitoring the changes in emission intensity, emission wavelength and / or emission color of the material under different external stimuli, solvent identification, viscosity monitoring and pressure response detection can be achieved, as well as for anti-counterfeiting display or optical information storage.

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