Acylhydrazone covalent organic framework material with pentadentate coordination environment as well as preparation method and application of acylhydrazone covalent organic framework material

Abstract

The invention belongs to the technical field of covalent organic framework functional materials, and particularly relates to an acylhydrazone covalent organic framework material with a pentadentate coordination environment as well as a preparation method and application of the acylhydrazone covalent organic framework material. The invention discloses an acylhydrazone covalent organic framework (COFs) with a pentadentate coordination center. The COFs are cooperatively driven and constructed by covalent bonds and coordination bonds, covalent assembly and metal coordination processes are synchronously realized, and unification of multiple structures, high crystallinity and excellent chemical stability is realized. Wherein a unique 'U-shaped' five-tooth coordination center generated by induction of a metal template can realize conversion of 'U-shaped' and 'W-shaped' structures along with reversible deintercalation of metal ions, metal ions such as Cu < 2 + > are introduced through a re-metallization strategy, and the coordination center can be converted into a 'J-shaped' structure, so that dynamic reversible conversion of 'UWJ' three configurations is realized in the same COFs framework, and the COFs can be used for preparing the COFs. The application potential in the fields of photocatalytic coenzyme NAD < + > regeneration and the like is endowed.

Description

Technical Field

[0001] This invention belongs to the technical field of covalent organic framework functional materials. More specifically, it relates to an acylhydrazone covalent organic framework material with a pentadentate coordination environment, its preparation method, and its applications. Background Technology

[0002] Covalent organic frameworks (COFs) are crystalline porous materials formed by covalently connecting organic structural units. Their structure and function are highly dependent on the diversity of linking chemistry. Theoretically, the targeted design and functional customization of COFs can be achieved by selecting building blocks and controlling the connection methods. Since the first report of COFs in 2005, researchers have successively developed various linking chemistry such as imines, borate esters, and acylhydrazones, and successfully constructed numerous COF structures. However, due to the inherent limitations of carbon atom hybridization in organic building blocks, the types of reported COF structures remain relatively limited, especially for two-dimensional COFs, which exhibit only about a dozen topological networks. This bottleneck severely restricts their potential for functional-oriented material customization and practical applications.

[0003] Against this backdrop, research on the synthesis of COFs is gradually shifting from static structures to dynamic system design. Inspired by the functional conversion achieved through conformational changes in biomolecular machines, introducing controllable structural responsiveness and conversion capabilities into COFs is considered an important approach to overcome their structural limitations and enrich their functional performance. External stimuli such as light, heat, pH, or guest molecules can induce reversible changes in pore size, surface chemistry, or interlayer distance in COFs, thereby dynamically regulating their behavior in catalysis, adsorption, and recognition. Although this dynamic design concept shows great potential, its development still faces significant challenges: on the one hand, the precise construction of complex topological COF frameworks presents synthetic difficulties; on the other hand, how to achieve efficient and reversible switching between different configurations while maintaining structural integrity and cycling stability remains a key scientific problem that has not yet been fully solved.

[0004] Therefore, promoting the development of novel linker chemistry and the innovation of dynamic construction strategies, and thereby realizing controllable configurational transformation and functional regulation in complex topological COFs, is of great significance for expanding the structural types and application prospects of COF systems. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of traditional COFs, which are limited in structural types and difficult to achieve dynamic configuration transformation, thus restricting their application expansion, and to provide an acylhydrazone covalent organic framework material with dynamic transformation characteristics.

[0006] Another object of the present invention is to provide a method for preparing acylhydrazone covalent organic framework materials.

[0007] Another object of the present invention is to provide an acylhydrazone covalent organic framework material obtained by the preparation method described above.

[0008] Another object of the present invention is to provide applications of the above-mentioned acylhydrazone covalent organic framework materials.

[0009] The above-mentioned objective of this invention is achieved through the following technical solution: This invention protects an acylhydrazone covalent organic framework material, wherein the acylhydrazone covalent organic framework material has any one of the following structures: ; Wherein, the R 1 R 2 Each is independently selected from hydrogen and C. 1~10 Alkyl or C 1~10 alkoxy group; the R 3 R 4 R 5 R 6 Each is independently selected from hydrogen and C. 1~10 Alkyl or C 1~10 Alkyl group.

[0010] This invention discloses for the first time the aforementioned acylhydrazone covalent organic frameworks (COFs) with pentadentate coordination centers. These COFs are constructed through a synergistic drive of covalent and coordination bonds, simultaneously achieving covalent assembly and metal coordination processes, thus unifying structural diversity with high crystallinity and excellent chemical stability. The unique "U-shaped" pentadentate coordination centers induced by the metal template can transform from "U-shaped" to "W-shaped" structures through reversible insertion / extraction of metal ions. This can be achieved by introducing metals such as Cu through a remetallization strategy. 2+ Metal ions can transform the coordination center into a "J-type" structure, thereby achieving a "U" structure within the same COF framework. W The dynamic reversibility of the three J” configurations, and endowing it with the ability to photocatalyze the coenzyme NAD. + Its application potential in fields such as recycling.

[0011] Furthermore, the R 1 R 2 Each is independently selected from hydrogen or C. 1~6 Alkyl group.

[0012] Preferably, the R 1 R 2 Each is independently selected from hydrogen or C. 1~3 Alkyl group.

[0013] Specifically, the C 1~3The alkoxy group can be methoxy, ethoxy, or propoxy.

[0014] More preferably, the R 1 R 2 Each is independently selected from hydrogen, methoxy, or ethoxy.

[0015] Preferably, the R 3 R 4 R 5 R 6 Each is independently selected from C 5~7 Alkyl group, more preferably -OC6H 13 .

[0016] This invention protects a method for preparing an acylhydrazone covalent organic framework material, comprising the following steps: S1. The acetal monomer, hydrazide monomer, metal salt, organic solvent and water are mixed evenly, degassed by freezing and then heated until the reaction is complete. After post-treatment, the hydrazone covalent organic framework material COF-LIFM-13 is obtained. S2. The COF-LIFM-13 obtained in step S1 is subjected to demetallization treatment to obtain the demetallized acylhydrazone covalent organic framework material COF-LIFM-13-De; S3. The COF-LIFM-13-De obtained in step S2 is mixed with a metal salt solution and subjected to post-metallization treatment to obtain the remetallized acylhydrazone covalent organic framework material COF-LIFM-13-M; When the metal ion species of the metal salt described in step S3 are the same as those described in step S1, COF-LIFM-13-M and COF-LIFM-13 are the same. When the types of metal ions in the metal salt described in step S3 are different from those in step S1, COF-LIFM-13-M and COF-LIFM-13 are not the same. The COF-LIFM-13, COF-LIFM-13-De, or COF-LIFM-13-M are the acylhydrazone covalent organic framework materials. The structural formula of the acetal monomer is as follows: The R 3 R 4 R 5 R 6 Each is independently selected from hydrogen and C. 1~10 Alkyl or C 1~10 Alkoxy; The structural formula of the hydrazide monomer is: The R 1 R 2 Each is independently selected from hydrogen and C. 1~10 Alkyl or C 1~10Alkoxy; The metal ions of the metal salts described in steps S1 and S3 are each independently selected from Zn. 2+ Fe 2+ Co 2+ Ni 2+ Cu 2+ Mn 2+ Cd 2+ Ag + At least one of them.

[0017] The aforementioned COF-LIFM-13, COF-LIFM-13-De, and COF-LIFM-13-M are merely formal designations and have no technical limitations.

[0018] Preferably, the R 3 R 4 R 5 R 6 Each is independently selected from C 5~7 Alkyl group.

[0019] Further, the demetallization process includes the following steps: mixing the material with a strong acid or strong alkali solution, allowing it to stand for a while, and then performing post-treatment to obtain the demetallized acylhydrazone covalent organic framework material COF-LIFM-13-De.

[0020] Preferably, the concentration of the strong acid or strong alkali solution is 3~12 M. Metal removal can be achieved within this range.

[0021] Preferably, the strong acid includes hydrochloric acid.

[0022] Preferably, the strong base includes sodium hydroxide.

[0023] In the above-mentioned demetallization process, the post-processing includes washing and drying.

[0024] Furthermore, the washing process involves washing with water and ethanol sequentially.

[0025] Furthermore, the drying conditions are: vacuum drying at 60~100 ℃ (preferably 80 ℃) for 6~18 h (preferably 12 h).

[0026] Preferably, the mixing method is ultrasonic treatment.

[0027] Preferably, the sufficient settling time is 2 to 48 hours at room temperature, more preferably 20 to 28 hours.

[0028] Furthermore, the metal salt includes its hydrate.

[0029] Preferably, the metal ion of the metal salt is Zn. 2+and Cu 2+ Zn is preferred. 2+ .

[0030] Preferably, the anion of the metal salt is selected from SO3CF3. - (CF3SO2)2N - NO3 - C5H7O2 - CH3COO - One of them, more preferably SO3CF3 - (CF3SO2)2N - NO3 - .

[0031] Furthermore, the R 3 R 4 R 5 R 6 Each is independently selected from C 5~8 Alkyl group.

[0032] Preferably, the acetal monomer is .

[0033] Furthermore, the R 1 R 2 Each is independently selected from hydrogen or C. 1~6 Alkyl group.

[0034] Preferably, the R 1 R 2 Each is independently selected from hydrogen or C. 1~3 Alkyl group.

[0035] Specifically, the C 1~3 The alkoxy group can be methoxy, ethoxy, or propoxy.

[0036] More preferably, the hydrazide monomer is 2,5-diethoxybenzene-1,4-bis(formylhydrazide).

[0037] Preferably, the molar ratio of the acetal monomer to the hydrazide monomer is 1:(1~4), more preferably 1:(2~3), and most preferably 1:2.5.

[0038] Preferably, the molar ratio of the acetal monomer to the metal salt can be 1:(1~8), more preferably 1:(3~5), and most preferably 1:4.

[0039] Preferably, the organic solvent is selected from one or more of acetonitrile, mesitylene, benzyl alcohol, methanol, n-butanol, o-dichlorobenzene, and 1,4-dioxane.

[0040] Furthermore, the organic solvent is preferably a combination of a first organic solvent and a second organic solvent, wherein the first organic solvent and the second organic solvent are different.

[0041] Furthermore, the first organic solvent and the second organic solvent are each independently selected from acetonitrile, mesitylene, benzyl alcohol, methanol, n-butanol, o-dichlorobenzene, or 1,4-dioxane.

[0042] Preferably, the volume ratio of the first organic solvent to the second organic solvent is (1~9):1, more preferably (2.3~9):1.

[0043] In a preferred embodiment, the organic solvent is preferably any combination of the following: a combination of acetonitrile and methanol, a combination of acetonitrile and 1,4-dioxane, or a combination of 1,4-dioxane and methanol.

[0044] Preferably, the volume ratio of water to organic solvent is 1:(2~5), more preferably 1:(3~4).

[0045] Preferably, the temperature at which the reaction is completed is 100~150 ℃, more preferably 120 ℃.

[0046] Preferably, the reaction takes 12 to 120 hours to complete, and more preferably 48 hours.

[0047] Furthermore, the temperature for the cryogenic degassing process is 77 K.

[0048] Furthermore, the cryogenic degassing process involves degassing until the system pressure reaches 0 bar.

[0049] Furthermore, the cryogenic degassing process also includes a thawing process, wherein thawing is the process of restoring the temperature to room temperature.

[0050] Furthermore, in step S1, the post-processing includes washing and drying.

[0051] Furthermore, the washing process involves sequentially washing with dimethyl sulfoxide, acetonitrile, tetrahydrofuran, and diethyl ether.

[0052] Furthermore, the drying conditions are: vacuum drying at 60~100 ℃ (preferably 80 ℃) for 6~18 h (preferably 12 h).

[0053] Furthermore, in step S3, the mixing method in the above metallization process is ultrasonic treatment.

[0054] Furthermore, the ultrasonic treatment also includes allowing the device to stand for a sufficient period of time.

[0055] Preferably, the sufficient settling time is 4 to 24 hours at room temperature, more preferably 11 to 13 hours.

[0056] The post-processing includes washing and drying.

[0057] Furthermore, the washing process involves sequential washing with acetonitrile and ether.

[0058] Furthermore, the drying conditions are: vacuum drying at 60~100 ℃ (preferably 80 ℃) for 6~18 h (preferably 12 h).

[0059] This invention also protects the acylhydrazone covalent organic framework material prepared by the aforementioned preparation method.

[0060] This invention also protects the acylhydrazone covalent organic framework material in the photocatalytic conversion of NADH to NAD. + Applications in [the field].

[0061] Compared with the prior art, the present invention has the following beneficial effects: (1) The acylhydrazone covalent organic framework prepared by the present invention is assembled by covalent bonds and coordination bonds, which effectively enhances the reversibility and fault tolerance of the reaction process, which is conducive to improving the quality of the material and obtaining long-range ordered crystalline materials with high crystallinity. (2) The acylhydrazone covalent organic framework prepared by this invention has excellent chemical and thermal stability; (3) The acylhydrazone covalent organic framework prepared by this invention has a unique "U-shaped" pentadecanodentate coordination center, which is induced by a metal template. Furthermore, with the reversible removal and insertion of the metal template, the transformation between the "U-shaped" and "W-shaped" structures can be achieved. In addition, based on the remetallization method, other metal ions such as Cu... 2+ It can also be easily fitted onto the COF framework, thereby turning into a "J-shaped" structure. Attached Figure Description

[0062] Figure 1 COF-LIFM-13 of Example 1 achieves "U" under metal induction. W A schematic diagram of the reversible configuration transformation of "J".

[0063] Figure 2 The experimental and refined PXRD spectra of COF-LIFM-13 in Example 1 are shown.

[0064] Figure 3 The infrared spectra of COF-LIFM-13 and monomers A and B in Example 1 are shown.

[0065] Figure 4 N2 adsorption of COF-LIFM-13 in Example 1 Desorption curve.

[0066] Figure 5 The TEM spectrum of COF-LIFM-13 in Example 1 is shown.

[0067] Figure 6 The image shows the EDS spectrum of COF-LIFM-13 from Example 1.

[0068] Figure 7 The TGA spectrum of COF-LIFM-13 in Example 1 is shown.

[0069] Figure 8 The image shows the PXRD pattern of COF-LIFM-13 from Example 1 after immersion in a common organic solvent for one day.

[0070] Figure 9 The PXRD spectra of COF-LIFM-13 from Example 1 after soaking in 12 M HCl (red) and 12 M NaOH (green) for one day, and after remetallization with zinc nitrate (blue and purple), respectively.

[0071] Figure 10 The experimental and refined PXRD spectra of COF-LIFM-13-De in Example 6 are shown.

[0072] Figure 11 N2 adsorption of COF-LIFM-13-De in Example 6 Desorption curve.

[0073] Figure 12 The TEM spectrum of COF-LIFM-13-De in Example 6 is shown.

[0074] Figure 13 The PXRD spectra of COF-LIFM-13 from Example 1 and COF-LIFM-13-De from Example 6 after three cycles of transformation are shown.

[0075] Figure 14 The experimental and refined PXRD spectra of COF-LIFM-13-Cu in Example 7 are shown.

[0076] Figure 15 N2 adsorption of COF-LIFM-13-Cu in Example 7 Desorption curve.

[0077] Figure 16 The TEM spectrum of COF-LIFM-13-Cu in Example 7 is shown.

[0078] Figure 17 The image shows the EDS spectrum of COF-LIFM-13-Cu from Example 7.

[0079] Figure 18The solid-state UV-Vis absorption spectra of COF-LIFM-13 in Example 1, COF-LIFM-13-De in Example 6, and COF-LIFM-13-Cu in Example 7 are shown.

[0080] Figure 19 The Tauc diagrams are for COF-LIFM-13 of Example 1, COF-LIFM-13-De of Example 6, and COF-LIFM-13-Cu of Example 7.

[0081] Figure 20 The chart shows the NADH consumption data of COF-LIFM-13 as a photocatalyst in Example 1 at different time periods.

[0082] Figure 21 The chart shows the NADH consumption data of COF-LIFM-13-De as a photocatalyst in Example 6 at different time periods.

[0083] Figure 22 The graph shows the NADH consumption data of COF-LIFM-13-Cu as a photocatalyst in Example 7 at different time periods.

[0084] Figure 23 The graph shows the conversion rate of NADH photocatalyzed by COF-LIFM-13 in Example 1, COF-LIFM-13-De in Example 6, and COF-LIFM-13-Cu in Example 7.

[0085] Figure 24 COF-LIFM-13 in Example 1 in the photocatalytic NAD + FT-IR spectra before and after the regeneration experiment. Detailed Implementation

[0086] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0087] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0088] The following monomer A is referenced in a previously reported article (Xu, H.-S.; Luo, Y.; Li, R.; Jiao, W.-N.; Huang, S.; Zhu, W.-D.; Wang, H.; Chen, T.; Nero, M.; Chen, F.; et al. Hierarchical assembly of tubular frameworks driven by covalent and coordinatebonding). Nat. Synth Prepared by .2024, 3 (12), 1498-1506. DOI:10.1038 / S44160-024-00632-3).

[0089] Example 1: Preparation of COF-LIFM-13 Take a 10mL pressure-resistant tube and add monomer A into it: The following monomers were added: (17.3 mg, 0.016 mmol), monomer B: 2,5-diethoxybenzene-1,4-bis(formylhydrazine) (11.3 mg, 0.040 mmol), Zn(NO3)2·6H2O (19.0 mg, 0.064 mmol), followed by 0.9 mL acetonitrile, 0.1 mL methanol, and 0.3 mL deionized water. The pressure tube was then degassed at 77 K until the system pressure reached 0 bar. After the pressure tube returned to room temperature, it was placed in an oven at 120 °C for 2 days. After the reaction, the solid was transferred to a centrifuge tube and washed sequentially with dimethyl sulfoxide, acetonitrile, tetrahydrofuran, and diethyl ether. After vacuum drying at 80 °C for 12 hours, an orange powder was obtained, which was named COF-LIFM-13.

[0090] Example 2 Preparation of COF-LIFM-13-2 Take a 10mL pressure-resistant tube and add monomer A into it: The following monomers were added sequentially: (17.3 mg, 0.016 mmol), monomer B: 2,5-diethoxybenzene-1,4-bis(formylhydrazine) (11.3 mg, 0.040 mmol), Zn(SO3CF3)2·6H2O (23.3 mg, 0.064 mmol), followed by 0.7 mL of 1,4-dioxane, 0.3 mL of methanol, and 0.3 mL of deionized water. The pressure-resistant tube was then degassed at 77 K until the system pressure reached 0 bar. After the pressure-resistant tube returned to room temperature, it was placed in an oven at 120 °C for 2 days. After the reaction, the solid was transferred to a centrifuge tube and washed sequentially with dimethyl sulfoxide, acetonitrile, tetrahydrofuran, and diethyl ether. After vacuum drying at 80 °C for 12 hours, an orange powder was obtained, and the material was named COF-LIFM-13-2.

[0091] Example 3 Preparation of COF-LIFM-13-3 Take a 10mL pressure-resistant tube and add monomer A into it: The following monomers were added sequentially: (17.3 mg, 0.016 mmol), monomer B: 2,5-diethoxybenzene-1,4-bis(formylhydrazine) (11.3 mg, 0.040 mmol), zinc bis(trifluoromethanesulfonyl)imide (40.0 mg, 0.064 mmol), followed by 0.9 mL acetonitrile, 0.1 mL 1,4-dioxane, and 0.3 mL deionized water. The pressure tube was then degassed at 77 K until the system pressure reached 0 bar. After the pressure tube returned to room temperature, it was placed in an oven at 120 °C for 2 days. After the reaction, the solid was transferred to a centrifuge tube and washed sequentially with dimethyl sulfoxide, acetonitrile, tetrahydrofuran, and diethyl ether. After vacuum drying at 80 °C for 12 hours, an orange powder was obtained, and the material was named COF-LIFM-13-3.

[0092] Example 4: Preparation of COF-LIFM-13-4 Take a 10mL pressure-resistant tube and add monomer A into it: The reaction mixture consisted of monomer B: terephthalohydrazide (7.76 mg, 0.040 mmol), Zn(NO3)2·6H2O (19.0 mg, 0.064 mmol), followed by 0.9 mL acetonitrile, 0.1 mL 1,4-dioxane, and 0.3 mL deionized water. The pressure-resistant tube was then degassed at 77 K until the system pressure reached 0 bar. After the pressure-resistant tube returned to room temperature, it was placed in an oven at 120 °C for 2 days. After the reaction, the solid was transferred to a centrifuge tube and washed sequentially with dimethyl sulfoxide, acetonitrile, tetrahydrofuran, and diethyl ether. After vacuum drying at 80 °C for 12 hours, an orange powder was obtained, which was named COF-LIFM-13-4.

[0093] Example 5 Preparation of COF-LIFM-13-5 Take a 10mL pressure-resistant tube and add monomer A into it: The following monomers were added sequentially: (17.3 mg, 0.016 mmol), monomer B: 2,5-dimethoxyphenyl-1,4-bis(formylhydrazine) (12.54 mg, 0.040 mmol), Zn(NO3)2·6H2O (19.0 mg, 0.064 mmol), followed by 0.9 mL of 1,4-dioxane, 0.1 mL of methanol, and 0.3 mL of deionized water. The pressure-resistant tube was then degassed at 77 K until the system pressure reached 0 bar. After the pressure-resistant tube returned to room temperature, it was placed in an oven at 120 °C for 2 days. After the reaction, the solid was transferred to a centrifuge tube and washed sequentially with dimethyl sulfoxide, acetonitrile, tetrahydrofuran, and diethyl ether. After vacuum drying at 80 °C for 12 hours, an orange powder was obtained, and the material was named COF-LIFM-13-5.

[0094] Example 6 Preparation of COF-LIFM-13-De The COF-LIFM-13 (20 mg) obtained in Example 1 was mixed with 5.0 mL of HCl or NaOH solution (3, 6, or 12 M) in a 10 mL centrifuge tube, sonicated, and then allowed to stand at room temperature for 24 hours to ensure Zn²⁺ content. + Complete removal of ions. The resulting solid was thoroughly washed with deionized water and ethanol in sequence, and dried under vacuum at 80°C for 12 hours. The resulting material was named COF-LIFM-13-De.

[0095] Example 7 Preparation of COF-LIFM-13-Cu The demetallizing material COF-LIFM-13-De (10 mg) was mixed with Cu(NO3)2·3H2O solution (100 mg dissolved in 5.0 mL acetonitrile solution), sonicated, and then allowed to stand at room temperature for 12 hours. The solid was then collected by centrifugation, washed thoroughly with acetonitrile and diethyl ether in sequence, and dried under vacuum at 80 °C for 12 hours. The resulting material was named COF-LIFM-13-Cu.

[0096] Experimental Example like Figure 1 As shown, the COF-LIFM-13 material obtained in Example 1 has a unique "U-shaped" ( U -shape) five-tooth coordination centers, and after acid or alkali treatment, Zn² can be achieved + The removal of the material yields a "W-shaped" product. W COF-LIFM-13-De (i.e., the material prepared in Example 6) with a J-shaped structure was obtained by remetallization using an acetonitrile solution of Cu(NO3)2•3H2O to obtain a J-shaped structure. J The COF-LIFM-13-Cu (i.e., the material prepared in Example 7) with a shape of -shape is shown. It can be seen that this invention designs and synthesizes a series of novel acylhydrazone covalent organic frameworks (COFs) with metal-induced reversible structural transformation characteristics, enabling the realization of "U" within the same COF framework. W Dynamic reversibility of the three J configurations.

[0097] The PXRD of the material COF-LIFM-13 prepared in Example 1 is as follows: Figure 2 As shown, its good crystallinity is confirmed. The main difference between Examples 2-3 and Example 1 is the use of different zinc salts. Using different zinc salts, the acylhydrazone covalent organic framework materials with the above-mentioned specific structures can all be synthesized, and their PXRD is almost identical to that of Example 1. The main difference between Examples 4-5 and Example 1 is the different substituents on the acylhydrazide monomers used; they can also synthesize... Figure 1 The PXRD pattern of the COF material with the "U-shaped" structure shown is almost identical to that of Example 1. The COF-LIFM-13 prepared in Example 1 will be used as a representative COF material for subsequent tests.

[0098] The Fourier transform infrared (FT-IR) spectrum of COF-LIFM-13 prepared in Example 1 is as follows: Figure 3 The display shows that at 1113cm -1 (corresponding to the acetal group in monomer A) and 3321 cm -1 1615 cm -1The peaks at (corresponding to the NH and C=O groups in monomer B, respectively) disappear, while the peak at 1630 cm⁻¹ disappears. -1 1602 cm -1 Characteristic signals corresponding to C=O and C=N bonds can be observed at 1384 cm⁻¹, respectively. -1 NO3 appeared at the location - The characteristic peaks confirmed the successful synthesis of acylhydrazone COFs.

[0099] Example 1: 77 K nitrogen adsorption test results of COF-LIFM-13 are as follows: Figure 4 As shown, a type I adsorption isotherm is presented, with a BET specific surface area of ​​330 m². 2 / g, with a pore size distribution of 1.01 nm, indicating the formation of a microporous structure.

[0100] Figure 5 High-resolution TEM spectra of COF-LIFM-13 prepared in Example 1 are shown, demonstrating its long-range structural order, and the magnified region matches the structure model simulated by superimposed MS.

[0101] EDS results are as follows Figure 6 As shown, the uniform distribution of C, N, O, and Zn elements in the COF-LIFM-13 prepared in Example 1 is confirmed.

[0102] Thermogravimetric analysis (TGA) of the COF-LIFM-13 prepared in Example 1 showed that it had excellent thermal stability, losing some stability at 250°C due to the removal of nitrate ions, and only experiencing framework collapse at around 340°C. Figure 7 It retains its crystallinity even after being soaked in common chemical reagents for 24 hours. Figure 8 Further, the samples were immersed in 12 M HCl and NaOH aqueous solutions for 24 hours, respectively. Figure 9 As shown, although its crystallinity is somewhat affected (12 M HCl: red line, 12 M NaOH: green line), it can be restored by subsequent remetallization treatment with acetonitrile solution of Zn(NO3)2•6H2O (blue and purple lines). These results collectively demonstrate that COF-LIFM-13 has excellent structural stability and can maintain crystallinity and chemical integrity under stringent conditions.

[0103] After acid or alkali treatment, COF-LIFM-13 from Example 1 can achieve Zn²⁺. + The removal of metals resulted in the material being named COF-LIFM-13-De (i.e., the material obtained in Example 6), and its PXRD was as follows: Figure 10 As shown, with the removal of metal, the structure of COF-LIFM-13-De changes, and the pore size increases to 2.05 nm (as shown). Figure 11 TEM images show that the lattice spacing of COF-LIFM-13-De is 2.7 nm. Figure 12 The reversible structural transformation between COF-LIFM-13 and COF-LIFM-13-De remains intact even after three cycles. Figure 13 ).

[0104] Based on the remetallization strategy, the COF-LIFM-13-De obtained in Example 6 was remetallized using an acetonitrile solution of Cu(NO3)2•3H2O to obtain COF-LIFM-13-Cu (i.e., the material obtained in Example 7). Crystallinity was assessed by PXRD, and the experimental results matched the simulation results from Materials Studio. Figure 14 ), because Cu at this time 2+ The unsaturated coordination mode of planar four-coordination is adopted, which transforms the coordination center into a J-type structure. The nitrogen adsorption test results at 77 K are as follows: Figure 15 As shown in the TEM image, the lattice spacing of COF-LIFM-13-Cu is 2.9 nm. Figure 16 EDS results confirm the uniform distribution of C, N, O, and Cu elements. Figure 17 The UV-Vis spectra show the metal-dependent light absorption characteristics of COF-LIFM-13, COF-LIFM-13-De, and COF-LIFM-13-Cu, indicating that the light absorption performance of the metal-controlled materials (…). Figure 18 , 19 ).

[0105] NAD + As a key coenzyme in the biological field, NAD plays an important role in biosynthesis and has wide applications, but its high cost constitutes a major challenge in practical applications. Therefore, developing efficient NAD... + Regeneration strategies are crucial for advancing the field of biosynthesis. Visible light-driven photochemical oxidation is particularly important for converting NADH to NAD+. + This method shows promising promise in terms of transformation, as it operates under mild conditions, mimics the mechanism of action of NADH oxidase in nature, and avoids the use of expensive enzymes.

[0106] The photocatalytic oxidation of NADH was carried out in Tris-HCl buffer solution. Photocatalysts with different electronic transition characteristics—COF-LIFM-13, COF-LIFM-13-De, and COF-LIFM-13-Cu—were selected to evaluate their photocatalytic oxidation performance for NADH under visible light (λ ≥ 400 nm) irradiation and ambient air. The specific procedure was as follows: 3.0 mg of the material, 2.0 mg of NADH, and 3.0 mL of Tris-HCl buffer (pH 7.5) were added to a 5 mL transparent glass vial. The suspension was equilibrated in the dark for 10 minutes. Subsequently, the vial was exposed to air under a xenon lamp with a filter (λ ≥ 400 nm). Samples were taken periodically, diluted 16-fold with Tris-HCl buffer (pH 7.5), and the change in NADH concentration at 340 nm was measured by UV-Vis spectroscopy.

[0107] The results showed that COF-LIFM-13 exhibited excellent catalytic activity, achieving a NADH conversion rate of >98% in just 8 minutes. Figure 20 In comparison, COF-LIFM-13-De has a lower conversion efficiency (). Figure 21 This is mainly due to its insufficient absorption of long-wavelength light in the visible light region. In contrast, COF-LIFM-13-Cu has the lowest photocatalytic activity ( Figure 22 , 23 This may be due to nonradiative deactivation caused by dd transitions. After photocatalytic testing, the material still maintains good structural stability. Figure 24 This demonstrates that the unique pentadentate coordination center in COF-LIFM-13 provides a simple strategy for immobilizing metal ions, thereby achieving efficient photochemical NAD under green and mild biomimetic conditions. + regeneration.

[0108] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An acylhydrazone covalent organic framework material, characterized in that, The acylhydrazone covalent organic framework material has any one of the following repeating unit structures: Wherein, the R 1 R 2 Each is independently selected from hydrogen and C. 1~10 Alkyl or C 1~10 alkoxy group; the R 3 R 4 R 5 R 6 Each is independently selected from hydrogen and C. 1~10 Alkyl or C 1~10 Alkyl group.

2. A method for preparing an acylhydrazone covalent organic framework material, characterized in that, Includes the following steps: S1. The acetal monomer, hydrazide monomer, metal salt, organic solvent and water are mixed evenly, degassed by freezing and then heated until the reaction is complete. After post-treatment, the hydrazone covalent organic framework material COF-LIFM-13 is obtained. S2. The COF-LIFM-13 obtained in step S1 is subjected to demetallization treatment to obtain the demetallized acylhydrazone covalent organic framework material COF-LIFM-13-De; S3. The COF-LIFM-13-De obtained in step S2 is mixed with a metal salt solution and subjected to post-metallization treatment to obtain the remetallized acylhydrazone covalent organic framework material COF-LIFM-13-M; When the metal ion species of the metal salt described in step S3 are the same as those described in step S1, COF-LIFM-13-M and COF-LIFM-13 are the same. When the types of metal ions in the metal salt described in step S3 are different from those in step S1, COF-LIFM-13-M and COF-LIFM-13 are not the same. The COF-LIFM-13, COF-LIFM-13-De, or COF-LIFM-13-M are the acylhydrazone covalent organic framework materials. The structural formula of the acetal monomer is as follows: The R 3 R 4 R 5 R 6 Each is independently selected from hydrogen and C. 1~10 Alkyl or C 1~10 Alkoxy; The structural formula of the hydrazide monomer is: The R 1 R 2 Each is independently selected from hydrogen and C. 1~10 Alkyl or C 1~10 Alkoxy; The metal ions of the metal salts described in steps S1 and S3 are each independently selected from Zn. 2+ Fe 2+ Co 2+ Ni 2+ Cu 2+ Mn 2+ Cd 2+ Ag + At least one of them.

3. The preparation method according to claim 2, characterized in that, The R 3 R 4 R 5 R 6 Each was independently selected from C 5~8 Alkyl group.

4. The preparation method according to claim 2, characterized in that, The R 1 R 2 Each is independently selected from hydrogen or C. 1~6 Alkyl group.

5. The preparation method according to any one of claims 2 to 4, characterized in that, The molar ratio of the acetal monomer to the hydrazide monomer is 1:(1~4).

6. The preparation method according to any one of claims 2 to 4, characterized in that, The molar ratio of the acetal monomer to the metal salt can be 1:(1~8).

7. The preparation method according to any one of claims 2 to 4, characterized in that, The organic solvent is selected from one or more of acetonitrile, mesitylene, benzyl alcohol, methanol, n-butanol, o-dichlorobenzene, and 1,4-dioxane.

8. The preparation method according to any one of claims 2 to 4, characterized in that, The volume ratio of water to organic solvent is 1:(2~5).

9. The acylhydrazone covalent organic framework material prepared by the preparation method according to any one of claims 2 to 8.

10. The acylhydrazone covalent organic framework material of claim 1 or the acylhydrazone covalent organic framework material of claim 9 in the photocatalytic conversion of NADH to NAD. + Applications in [the field].

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