CN114621407B

CN114621407B - Preparation and application of azine-based COFs covalent organic framework material

Info

Publication number: CN114621407B
Application number: CN202011454237.9A
Authority: CN
Inventors: 欧俊杰; 徐俊文; 马淑娟; 叶明亮
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2020-12-10
Filing date: 2020-12-10
Publication date: 2023-03-28
Anticipated expiration: 2040-12-10
Also published as: CN114621407A

Abstract

The invention develops a new strategy for synthesizing azine-based COFs, and the azine-based COFs are synthesized by replacing hydrazine hydrate with an aliphatic hydrazide compound, so that the use of hydrazine hydrate with high volatility and high toxicity is avoided, and the development trend of green chemistry is met. In the synthesis, two hydrazide compounds (mono-substituted acethydrazide and di-substituted tartaric acid dihydrazide) are considered as substitutes of hydrazine hydrate and polymerized with trimesic aldehyde to obtain azine-based COFs (ACOF-31 and ACOF-32) with good crystal forms. ACOF-31 and ACOF-32 respectively present a nanotube shape and a two-dimensional film shape, have fluorescence properties, can generate fluorescence enhancement phenomenon when meeting phenolic compounds, and can be used for fluorescence induction of the phenolic compounds.

Description

Preparation and application of azine-based COFs covalent organic framework material

Technical Field

The invention relates to the preparation of three different azine-based covalent organic frameworks and their use in the fluorescence sensing of phenolic compounds.

Background

Covalent Organic Frameworks (COFs) are a class of porous organic polymers with crystal structures, and the arrangement heights of the framework structures are orderly, so that the formed pore channel structures are very regular. Due to the unique synthetic strategy, COFs typically have a low framework density, a high specific surface area, and a highly uniform pore size distribution. In addition, the monomers used in the synthesis of COFs are usually aromatic compounds with rigid structures, and the skeletal structures involved in the construction generally have a large conjugated system, so that some of the COFs also have fluorescent or optoelectronic properties (1, geng et al, "valuable organic frameworks: designs, syntheses, and functions", "Chemical Reviews", 2020, 120, 8814-8933). COFs have received much attention since their report by Yaghi et al (document 2, yaghi et al, "ports, crystaline, equivalent organic frames", science, 2005, 210, 1166) due to their unique structure and excellent properties. With the progress of research, more and more reactions are beginning to be applied to the synthesis of COFs, the range of monomers used is wider and wider, and the COFs are gradually developed into a material family with abundant varieties. Azine-based COFs (ACOFs) are small branches of COFs and are polymerized by amine-aldehyde condensation reaction, amine monomers are generally fixed as hydrazine, and aldehyde monomers are relatively selected. In 2013, vyas et al (reference 3, vyas et al, "A tunable azo synergistic organic frame platform for visible light-induced hydrogen generation", nature Communications, 2015,6, 8508) reported the first example of ACOFs, and the reaction of aldehyde derivatives of pyrene with hydrazine hydrate resulted in COFs with strong fluorescence characteristics and applied to the detection of nitro explosives. More aldehydes were subsequently used in the synthesis of ACOFs, including 1,3,5-trimethylacylbenzene, trialdehyde phloroglucinol, and 1,3,5-tris (p-formylphenyl) benzene, among others. With the abundance of ACOFs, the application fields of the ACOFs are wider and wider, including the adsorption and separation of gases, catalysis, heavy metal adsorption and the like.

Fluorescent materials have been receiving wide attention, and are widely used in the fields of sensing, biological probes, photoelectricity, photovoltaics, and the like. Compared with fluorescent high molecular polymers, fluorescent small molecules have the advantages of easy availability and low cost, but have the problems of low sensitivity, poor stability and difficulty in recycling. Compared with the conventional one-dimensional or three-dimensional polymerization system, the space structure of the COFs can be preset and regulated, and the pi conjugated fluorescent building block can be accurately introduced into the polymerization system to obtain the COFs with excellent fluorescence performance. Fluorescent COFs have a certain research basis (refer to 4, xue et al, "Fluorescence properties and Analytical applications of quantitative organic structures", analytical Methods, 9, 3737-3750), and are also widely used in sensing aspects based on their fluorescent properties, and the detection targets relate to explosives, volatile organic compounds, heavy metal ions, anions, biomolecules, and the like. In this chapter of work, we find that azine-based COFs have a fluorescence enhancement phenomenon when encountering a phenolic compound, and can be used for sensing phenolic pollutants (such as bi-2-naphthol), thereby further expanding the sensing application range of fluorescent COFs.

In the reported synthesis of azine-based COFs, all amine-based monomers used were hydrazine hydrate. However, hydrazine hydrate is volatile and highly toxic, and does not meet the trend of green chemistry. We have found that aliphatic hydrazide compounds decompose to form hydrazine when heated, and therefore have attempted to synthesize azinyl COFs using them as substitutes for hydrazine hydrate, resulting in the successful preparation of ACOFs (designated ACOF-31) by polycondensation using acetohydrazide and trimesic aldehyde. As a control, we also synthesized the original ACOF-3 using hydrazine hydrate as a monomer, which was proved to be substantially identical in chemical composition and structure to the ACOFs synthesized by the new method by various characterization means, but the ACOF-31 synthesized using acethydrazide as a monomer and the original ACOF-3 have significant difference in micro-morphology, the former being in the form of nanotubes and the latter being in the form of irregular vesicles. In addition to acetohydrazide, we also examined the polyhydrazide compound, tartaric acid dihydrazide, and as a result, obtained another ACOFs in a two-dimensional film form (denoted as ACOF-32). The three ACOFs with different morphologies have fluorescence characteristics, and can generate fluorescence enhancement display phenomenon when encountering phenol, and can be used for detecting phenol pollutants.

Disclosure of Invention

The invention aims to provide a novel synthesis method of azine-based COFs, which adopts a hydrazide monomer with low toxicity and low volatility to replace the traditional hydrazine hydrate with high toxicity and high volatility to polymerize with trimesic aldehyde to obtain three COFs with completely different shapes.

In order to avoid the use of highly toxic and highly volatile hydrazine hydrate monomers, acethydrazide is used as an alternative. Various characteristics prove that acethydrazide is decomposed to generate hydrazine in the polymerization process, and finally the acethydrazide reacts with aldehyde monomer trimesic aldehyde in the form of hydrazine to be polymerized into azine-based ACOF-31 in the form of a nano tube.

Using another hydrazide compound of tartaric acid diacid as a hydrazine source to react with an aldehyde monomer of trimesic aldehyde to polymerize into ACOF-32 presenting a planar membranous azine group.

It was confirmed by characterization that ACOF-3, ACOF-31 and COF-32 synthesized using hydrazine hydrate, acetohydrazide and tartaric acid dihydrazide were substantially identical in chemical composition and structure.

ACOF-3, ACOF-31 and COF-32 are in the shape of irregular vesicles, nanotubes and films in the shape of planes respectively in the micro-topography. When the azine-based COFs meet phenolic compounds, fluorescence enhancement phenomenon occurs, and the azine-based COFs can be used for fluorescence induction. In order to achieve the purpose, the invention adopts the following specific technical scheme:

(1) Preparation of ACOF-31

0.050 to 0.055g of acethydrazide and 0.075 to 0.080g of trimesic aldehyde are weighed into a 20mL headspace bottle, and then 2.5 to 3.5mL of 1, 4-dioxane, 5.5 to 6.5mL of mesitylene and 0.6 to 1.8mL of 3 to 6M acetic acid solution are added. And (3) after the reaction system is subjected to ultrasonic treatment for 5-15 min, introducing argon into the bottle for 3-10 min, and then sealing the headspace bottle. And (3) putting the sealed headspace bottle into an oven at 110-130 ℃ to heat for 72-96 h for polymerization reaction. After the reaction was completed and cooled to room temperature, the reaction system was poured into a 50mL centrifuge tube, and a yellow solid was collected by centrifugation. Firstly, the yellow solid is respectively washed three times by DMF and THF, then THF is used for washing for 12-36 h by a Soxhlet extraction method, and finally vacuum drying is carried out for 12-36 h at 60-100 ℃ to obtain yellow powdery ACOF-31.

(2) Preparation of ACOF-3

0.075 to 0.080g of trimesic aldehyde is weighed into a 20mL headspace bottle, and then 2.5 to 3.5mL of 1, 4-dioxane, 5.5 to 6.5mL of mesitylene, 30 to 40 MuL of 98 percent hydrazine hydrate and 0.6 to 1.8mL of 3 to 6M acetic acid solution are added. And (3) carrying out ultrasonic treatment on the reaction system for 5-15 min, introducing argon into the bottle for 3-10 min, and sealing the headspace bottle. And (3) putting the sealed headspace bottle into an oven at 110-130 ℃ to heat for 72-96 h for polymerization reaction. After the reaction was completed and cooled to room temperature, the reaction system was poured into a 50mL centrifuge tube, and a yellow solid was collected by centrifugation. Firstly, the yellow solid is respectively washed three times by DMF and THF, then THF is used for washing for 12-36 h by a Soxhlet extraction method, and finally vacuum drying is carried out for 12-36 h at 60-100 ℃ to obtain yellow powdery ACOF-31.

(3) Preparation of ACOF-32

Firstly, 0.030-0.035-g D-tartaric acid dihydrazide and 0.015-0.025 g trimesic aldehyde are weighed into an ampoule bottle, and then 2.5-3.5 mL of 1, 4-dioxane and 0.25-0.35mL of 3-6M acetic acid solution are added. After the ampoule bottle is subjected to ultrasonic treatment, the ampoule bottle is frozen by liquid nitrogen until the solution is completely solidified, then a hose is connected to the ampoule bottle through a bottle neck for vacuumizing, and finally the ampoule bottle is fused and sealed at the bottle neck. After the ampoule bottle is warmed up to the room temperature, the ampoule bottle is put into an oven at 110-130 ℃ to be heated for 72-96 h. After the reaction was completed, the ampoule was opened from the neck of the bottle, and then the reaction system was transferred to a 50mL centrifuge tube and a yellow solid was collected by centrifugation. Washing the yellow solid product with THF for 3 times, putting the product into a vacuum drying oven at 60-100 ℃ for vacuum drying for 12-36 h to finally obtain yellow powdery ACOF-32,

the invention has the advantages of

1. The invention provides a novel synthesis method of azine-based COFs, which adopts hydrazide monomers which are more environment-friendly and beneficial to human health to replace hydrazine hydrate with high toxicity and high volatility used in the traditional method.

2. The invention also adopts hydrazine hydrate monomer to synthesize azinyl COFs as a contrast, and compared with the traditional method, the method has higher usage of mesitylene in the reaction system. The obtained azinyl ACOF-3 has irregular vesicle morphology and is greatly different from amorphous azinyl COFs synthesized by a traditional method.

3. The synthetic ACOF-31 and ACOF-32 of the invention have more particular micro-topography, respectively presenting a nanotube shape and a two-dimensional film shape.

4. The three azine-based COFs synthesized by the method have fluorescence properties, and can be applied to fluorescence induction of phenolic substances.

Drawings

FIG. 1 Synthesis of ACOF-31 and ACOF-32.

FIG. 2 is an infrared spectrum of ACOF-3 (a) synthesized from hydrazine hydrate monomer, ACOF-31 (b) synthesized from acetohydrazide and ACOF-32 (c) synthesized from tartaric acid dihydrazide. . Observing the original ACOF-3 infrared spectrum, the result can be found in 1500-1700cm ^-1 The region has only C = N stretching and C-H bending vibration absorption peaks which are respectively positioned at 1632 cm and 1594cm ^-1 . However, in the infrared spectrum of ACOF-31, not only the above two characteristic peaks but also a peak at 1663cm were present in the same region ^-1 Of carbonyl groupsC = O stretching vibration absorption peak. The appearance of the characteristic carbonyl peak indicates that the decomposition of acetohydrazide is not complete, but a small amount of residue is left during the polymerization. In ACOF-32 synthesized by using tartaric acid dihydrazide, 1500-1700cm ^-1 Four characteristic peaks appear in the region, and compared with ACOF-31, three peaks are basically the same, and are more positioned at 1656cm ^-1 Also belonging to C = N stretching vibration, but this characteristic peak is not from an azine structure but from a hydrazone structure. The above results show that the polymerization process of ACOF-32 is more complicated than that of ACOF-31, the decomposition degree of the tartaric acid dihydrazide monomer is less complete, and even a part of the non-decomposed hydrazide monomer reacts with aldehyde to form hydrazone bond.

FIG. 3 of ACOF-3 (a) synthesized from hydrazine hydrate and ACOF-31 (b) synthesized from acethydrazide ¹³ C cross polarization magic angle rotating solid nuclear magnetic resonance spectrogram. The solid nuclear magnetic carbon spectrum spectrograms of ACOF-3 synthesized by hydrazine hydrate monomers and ACOF-31 synthesized by acethydrazide monomers are basically the same, and the same shows that in the synthesis of ACOF-31, acethydrazide is decomposed to generate hydrazine, and finally the reaction of hydrazine and aldehyde is equivalent to the generation of COFs. In the framework structures of ACOF-3 and ACOF-31, three carbon atoms with different chemical environments coexist, namely, the carbon atom on the imino group, the carbon atom on the benzene ring connected with the imino group and the carbon atom on the benzene ring not connected with the imino group, and the chemical shifts of the three are 162, 135 and 129ppm respectively. In addition, a carbon signal at a chemical shift of 201ppm was detected, and the signal intensity was very high. The carbon signal peak belongs to aldehyde group, which indicates that a large amount of aldehyde group residues exist in the reaction process, and the abnormality of the content of COFs oxygen element in the organic element analysis is also explained. Above 201ppm, there are two small carbon signal peaks belonging to hydrazide group and carboxylic acid group, which not only indicates that there is some acethydrazide not completely decomposed in the reaction, but also indicates that there is some aldehyde group oxidized into carboxyl group because the reaction system is not strictly deoxygenated. Other hetero-peaks are from residual organic solvent.

FIG. 4 Synthesis of ACOF-32 from tartaric acid dihydrazide ¹³ C cross polarization magic angle rotating solid nuclear magnetic resonance spectrogram. In addition to the carbon signal peak in FIG. 3, the spectrum of ACOF-32 synthesized from tartaric acid dihydrazide can be observedVery distinct peaks were observed for the tartaric acid monomer-related carbon signal as well as for the hydrazone-based carbon signal. The above-mentioned phenomenon indicates that the degree of decomposition of tartaric acid dihydrazide monomer is lower in the synthesis of ACOF-32, and that a considerable amount of non-decomposed hydrazide monomer reacts with aldehyde to form hydrazone oligomer impurities.

FIG. 5ACOF-31 (a) experimental and theoretical PXRD pattern comparisons for different stack models; PXRD patterns of ACOF-3 (b) and ACOF-32 (c); AA (e), AB (f), and ABC (g) stacked mode spatial stick ball models of ACOF-3. In PXRD spectrograms of ACOF-3, ACOF-31 and ACOF-32, a strong diffraction peak exists at about 7 degrees 2 theta and is located at substantially the same position. The diffraction peak belongs to a 100-plane reflection signal of a single crystal cell of a crystal material, reflects the size of the cell, and indicates that three COFs have the same cell size. The unit cell size is closely related to the size of a closed ring structure in the COFs structure, and data show that three COFs have the same closed ring structure, and indirectly prove that the acetohydrazide is decomposed into hydrazine in the polymerization process. ACOF-3 and ACOF-31 have highly similar PXRD spectra, indicating that both have substantially the same crystal structure. In addition to the strongest 100 diffraction peaks, the PXRD spectra of the two crystals also have signal peaks located at about 12 °, 21 ° and 27 °, which correspond to the 110-, 120-and 001-plane diffraction signals of the crystals, respectively. Planar polymer networks of two-dimensional COFs are vertically stacked by pi-pi interaction force, with certain gaps between layers. This gap is calculated to be about

Matched with the 100 plane 27 DEG diffraction peak. The spectrum of ACOF-32 has a strong diffraction peak at about 20 degrees besides the 4 diffraction peaks, which corresponds to the 20-degree diffraction peak in the ABC stack mode simulation spectrum. It is shown that in the ACOF-32 structure, the ratio of stacking between layers by means of ABC stack is large.

FIG. 6 shows the nitrogen adsorption/desorption curves and NLDFT pore size distribution of ACOF-3 (a, d), ACOF-31 (b, e) and ACOF-32 (c, f). Among the three COFs, the specific surface area of ACOF-3 synthesized by hydrazine hydrate monomer is highest and reaches 924m ² g ^-1 835m of ACOF-31 synthesized from acethydrazide monomer ² g ^-1 Secondly, the tartaric acid dihydrazide synthesized ACOF-32 is the lowest, only 362m ² g ^-1 . ACOF-3 and ACOF-31 have comparable specific surface areas, while ACOF-32 differs greatly from both, because the decomposition of monomeric tartaric acid dihydrazide is the least complete in the synthesis of ACOF-32, and a considerable portion reacts with aldehydes to form hydrazone oligomer impurities without pore structures, thereby resulting in a decrease in specific surface area. This has been demonstrated in the IR characterization that there is no C = N characteristic peak of hydrazone imine bond in the IR spectra of ACOF-3 and ACOF-31, but it is very clear in the spectrum of ACOF-32, indicating the presence of more hydrazone impurities. The closed-loop structure of ACOF-3 forms pores with a diameter of about 1.5nm as theoretically calculated, but the presence of this pore size is not found at all in the pore size distribution maps of the three COFs. There is a pore diameter of about 0.75nm, which is about half the theoretical value, in the pore diameter distribution of ACOF-3 and ACOF-31. This phenomenon indicates that in the layer-by-layer stacking of ACOF-3 and ACOF-31, the main stacking mode is not the AA stacking mode of the flow-through type, and if this mode is the mode, a pore diameter of about 1.5nm should exist. The pore diameter is half of the theoretical value because ACOF-3 and ACOF-31 are stacked layer by layer in the staggered AB stacking mode, thus showing the half structure of the theoretical closed ring, which is consistent with the experimental results of about 0.75 nm. Besides, the measured values of the apertures of ACOF-3 and ACOF-31 are 0.58nm, which shows that the layer-by-layer stacking of ACOF-3 and ACOF-31 not only has AB mode, but also has ABC mode with higher interleaving degree. This mode reveals that the actual pore structure is a one-third closed-loop structure, so the measured value of the pore diameter is also about one-third of the theoretical value. For ACOF-32, the pore size distribution range is substantially centered at 0.54nm, which indicates that the layer-by-layer stacking mode is dominated by the ABC mode. This phenomenon is also shown in the PXRD spectrum of ACOF-32, wherein there is a diffraction peak around 20 degrees which is relatively consistent with the PXRD simulation spectrum of ABC stacked mode, and the peak is not obvious in the other two ACOFs.

FIG. 7 is a scanning electron microscope and a transmission electron microscope image of ACOF-3 (a, d) synthesized from hydrazine hydrate, ACOF-31 (b, e) synthesized from acetohydrazide and ACOF-32 (c, f) synthesized from tartaric acid dihydrazide. ACOFs synthesized with different monomers, although very close in chemical structure and composition, differ greatly in microscopic morphology. ACOF-3 synthesized by hydrazine hydrate monomer is in irregular hollow vesicle shape in microscopic morphology, ACOF-31 synthesized by acethydrazide monomer is in hollow nanotube shape, and ACOF-32 synthesized by tartaric acid dihydrazide is in two-dimensional membrane structure. It is shown that in the polymerization reaction of ACOFs, the phase separation processes of polymers synthesized in different ways during precipitation in the reaction system are greatly different, and finally, great differences in the microscopic appearances of products are caused.

FIG. 8 fluorescence excitation (dotted line) and emission (solid line) spectra of an ACOF-32 acetonitrile suspension. COF-32 has the fluorescent characteristic, and the fluorescence excitation spectrum thereof shows that the maximum excitation wavelength of ACOF-32 is 390nm; the emission spectrum showed two maximum emission wavelengths of ACOF-32, 402 and 426nm, respectively.

FIG. 9 shows fluorescence spectra of a bis-2-naphthol acetonitrile solution (short line), an ACOF-32 acetonitrile suspension (dotted line), and an ACOF-32 suspension with added bis-2-naphthol acetonitrile (solid line). ACOF-32 exhibits fluorescence enhancement in the presence of phenolic compounds. The dotted line curve is the fluorescence emission spectrum of the experiment of the blank control group of ACOF-32, while the solid line part is the fluorescence emission spectrum of the experiment group (added with the target Iodobinaphthol), so that the fluorescence intensity of the experiment group is obviously stronger than that of the control group, and the result shows that the ACOF-32 suspension system has a fluorescence enhancement effect after the target Iodobinaphthol is added. In order to confirm the fluorescence enhancement phenomenon and eliminate interference of other factors, an ACOF-32 suspension background is independently subjected to a fluorescence test, and a bis-2-naphthol acetonitrile solution is excited by using the same excitation light, so that the emission light can be detected, but the light intensity is very weak compared with that of an ACOF-32 suspension system, the maximum emission wavelength is completely different from that of the suspension system, the possibility of generating fluorescence by acetonitrile or bis-2-naphthol is eliminated, and the influence of the experimental background on the expressed fluorescence enhancement phenomenon is very limited.

FIG. 10 (a) Effect of concentration of bis-2-naphthol on fluorescence emission intensity of ACOF-32 acetonitrile suspension (from bottom to top, bis-2-naphthol concentrations are 0, 200, 400, 600, and 800, respectively1000 ppm); (b) Linear relationship between concentration of bi-2-naphthol and fluorescence emission intensity of ACOF-32 suspension system, I and I ₀ Representing the intensity of fluorescence emission with and without added bi-2-naphthol, respectively. To further investigate the effect of bi-2-naphthol on the fluorescence emission intensity of ACOF-32, we investigated the effect of bi-2-naphthol concentration on the fluorescence intensity. In the experiment, a series of bis-2-naphthol acetonitrile solutions with the concentrations of 400 ppm, 800 ppm, 1200 ppm, 1600 ppm and 2000ppm are prepared and then mixed with an ACOF-32 suspension in equal volume. After an ACOF-32 suspension system mixed with different concentrations of the bi-2-naphthol is excited by 370nm light, the detected emission light intensity is increased along with the increase of the concentration of the bi-2-naphthol, and further analysis of relevant data can find that the concentration of the bi-2-naphthol and the emission light intensity have a good linear relation, and the linear correlation coefficient is 0.986.

FIG. 11 shows the effect of various compounds (benzalkonium chloride, a; ethanolamine, b; bisphenol A, c; camphorquinone, d) on the fluorescence emission spectrum of ACOF-32, the solid line curve representing the test group with the test substance added thereto, and the dotted line curve representing the blank control group without the test substance added thereto. In addition to bi-2-naphthol, other compounds were used to test the fluorescence response characteristics of ACOF-32, including benzalkonium, ethanolamine, bisphenol a (fig. 4.15 c), and camphorquinone. By analyzing fluorescence data, the fluorescence enhancement phenomenon can be shown in that the emission light intensity of an experimental group is stronger than that of a blank control group in an ACOF-32 suspension system added with benzyl carbinolamine, ethanolamine and bisphenol A; in the suspension system added with camphorquinone, the emission intensity of the experimental group is weaker than that of the blank control group, and the fluorescence quenching phenomenon is shown. The above phenomena show that in the fluorescence response test suspension system of ACOF-32, not all compounds can generate fluorescence enhancement phenomenon, and the influence of compounds with different properties on the fluorescence property of ACOF-32 is different. Target compounds capable of enabling ACOF-32 to generate fluorescence enhancement phenomenon include bi-2-naphthol, ethanolamine, benzyl carbinolamine and bisphenol A, and through analysis, the compounds are all electron-rich compounds, and when the compounds interact with ACOF-32 polymer skeletons, a part of self electrons can be transferred to COFs, so that the electron cloud density of the polymer skeletons of the COFs is increased, and further the emission light intensity is enhanced. Camphorquinone, which is different from the above four compounds in properties, contains a strongly polar carbonyl group, is an electron-withdrawing compound, and when interacting with the ACOF-32 polymer skeleton, will draw electrons from COFs, reducing the electron cloud density, and thus reducing the intensity of emitted light.

Detailed description of the preferred embodiments

Example 1

1. A20 mL headspace bottle was charged with acetohydrazide (0.053g, 0.72mmol) and trimesic aldehyde (0.078g, 0.48mmol).

2. To the above headspace bottle was added 1,4-dioxane (3.0 mL), mesitylene (6.0 mL), and 6M acetic acid solution (1.8 mL).

3. Mixing the above system with ultrasound for 15min.

4. And introducing argon into the system for 3min, and sealing the headspace bottle.

5. The sealed headspace bottle was reacted at 120 ℃ for 72h.

6. After the reaction was completed and cooled to room temperature, the reaction system was transferred to a 50mL centrifuge tube, and the supernatant was discarded by centrifugation to obtain a yellow solid.

7. The yellow solid obtained in step 7 was washed three times with each of DMF and THF.

8. The yellow solid was washed with THF by soxhlet extraction for 24h.

9. And (3) drying the washed yellow solid at 80 ℃ for 24h in vacuum to obtain the ACOF-31 product.

Example 2

1. To a 20mL headspace bottle was added trimesic aldehyde (0.078g, 0.48mmol).

2. To the headspace bottle, 1,4-dioxane (3.0 mL) and mesitylene (6.0 mL) were added

mL), 98 hydrazine hydrate (36. Mu.L) and 6M acetic acid solution (1.8 mL).

3. Mixing the above system with ultrasound for 15min.

5. The sealed headspace bottle was reacted at 120 ℃ for 72h.

8. The yellow solid was washed with THF by soxhlet extraction for 24h.

9. And (3) drying the washed yellow solid at 80 ℃ for 24h in vacuum to obtain the ACOF-3 product.

Example 3

1. D-tartaric acid dihydrazide (0.032g, 0.18mmol) and trimesic aldehyde (0.019g, 0.12mmol) were weighed into an ampoule.

2. To the ampoule was added 1,4-dioxane (3 mL) and 6M acetic acid solution (0.3 mL).

3. Mixing the above system with ultrasound for 15min.

4. The above system was frozen with liquid nitrogen.

5. The system was evacuated.

6. The ampoule is fused to seal the tube at the neck of the bottle.

7. The capped headspace vials were reacted for 72h at 120 ℃.

8. After the reaction was completed and cooled to room temperature, the reaction system was transferred to a 50mL centrifuge tube, and the supernatant was discarded by centrifugation to obtain a yellow solid.

9. The yellow solid obtained in step 7 was washed three times with THF.

10. And (3) drying the washed yellow solid at 80 ℃ for 24h in vacuum to obtain the ACOF-32 product.

11. ACOF-32 was thoroughly and uniformly ground.

12. 1mg of ACOF-32 powder was put into a 20mL headspace bottle, and 10mL of acetonitrile was added to prepare a 100mg/L suspension.

13. The suspension was then sonicated for 1h and magnetically stirred for 24h until ready for use.

14. 2mL of 100mg/L ACOF-32 suspension is taken, diluted to 100mL by acetonitrile, and then ultrasonic treatment is carried out for 1h, so as to obtain 2mg/L ACOF-32 detection solution.

15. ACOF-32 detection solution 1mL and acetonitrile 1mL are mixed uniformly and poured into a quartz cuvette for fluorescence detection, and ACOF-32 is found to have fluorescence characteristics (as shown in FIG. 8).

16. 1mL of ACOF-32 detection solution and 1mL of 1000ppm bi-2-naphthol acetonitrile solution are uniformly mixed, poured into a quartz cuvette for fluorescence detection, and the phenomenon of fluorescence enhancement after the addition of the bi-2-naphthol can be determined (as shown in figure 9).

17. 1mL of ACOF-32 detection solution and 1mL of a series of 2-naphthol acetonitrile solutions (the concentrations are respectively 400, 800, 1200, 1600 and 2000 ppm) are uniformly mixed, and the mixture is poured into a quartz cuvette for fluorescence detection, so that the fluorescence enhancement amplitude is enhanced along with the increase of the concentration of the 2-naphthol and is in a linear relationship (as shown in figure 10).

18. 1mL of ACOF-32 detection solution and 1mL of other acetonitrile solution to be detected are uniformly poured into a quartz cuvette for fluorescence detection, and the influence of different compounds on the fluorescence intensity of ACOF-32 is researched (as shown in FIG. 11).

Claims

1. A method for synthesizing azinyl COFs covalent organic framework materials is characterized in that:

adding polymeric monomers of acethydrazide and mesitylene triformol into a reaction container, and then adding a reaction solvent of 1,4-dioxane, mesitylene and a catalyst of 3-6M acetic acid solution, wherein the volume ratio of the acetyl hydrazide to the mesitylene triformol is 10:20:1~3; carrying out ultrasonic treatment on the reaction system for 5 to 15min, and then introducing argon; sealing the reaction container, and then heating at 110-130 ℃ for 72-96 h for polymerization reaction to obtain ACOF-31 in a nano-tube shape;

or adding polymerization monomers of D-tartaric acid dihydrazide and trimesic aldehyde into a reaction vessel, and then adding 1,4-dioxane and 3 to 6M acetic acid solution, wherein the volume ratio of the monomers is 10/1~3; freezing with liquid nitrogen until the solution is completely solidified, then vacuumizing the reaction container, and finally sealing the reaction container; after the reaction vessel is warmed up to room temperature, the reaction vessel is heated at 110 to 130 ℃ for 72 to 96 hours for polymerization reaction to obtain planar film-shaped ACOF-32.

2. The method of synthesis according to claim 1, characterized in that:

the mol ratio of the trimesic aldehyde to the acethydrazide is 1:0.8 to 1.2, wherein the molar ratio of the trimesic aldehyde to the D-tartaric acid dihydrazide is 1:0.8 to 1.2.

3. Azine-based COFs material obtainable by a process as claimed in claim 1 or 2 comprising nanotubular ACOF-31 or planar film ACOF-32.

4. An azine-based COFs material characterized by: comprising a nanotubular ACOF-31 or a planar film ACOF-32 according to claim 1;

wherein the polymer molecular structure of the covalent organic framework material is

。

5. Use of azine-based COFs material according to claim 3 or 4 as a fluorescent material.

6. Use according to claim 5, wherein the azine-based COFs are fluorescence sensitive to phenolic compounds, wherein the fluorescence enhancement occurs when the phenolic compounds are encountered.