COF photocatalyst, preparation method thereof and application of COF photocatalyst in photocatalytic regeneration of NADH

Abstract

The invention discloses a COF photocatalyst, a preparation method thereof and application of the COF photocatalyst in photocatalytic regeneration of NADH, the preparation method of the COF photocatalyst comprises the following steps: an aldehyde monomer and an amino monomer are subjected to a Schiff base condensation reaction, at least one of the aldehyde monomer and the amino monomer contains hydroxyl, and a covalent organic framework COF with a hydroxyl group is obtained; and carrying out a Williamson synthesis reaction on the covalent organic framework (COF) and a brominated alkyl ammonium salt, so as to obtain the COF photocatalyst. The COF photocatalyst is substantially quaternary ammonium salt modified COF, high positive charge density and specific configuration are given to the COF, the preparation method is simple, and the COF photocatalyst has the advantages of being high in enzyme regeneration efficiency, rapid in reaction, high in selectivity, easy and convenient to operate and the like after being used for photocatalytic regeneration of NADH.

Description

Technical Field

[0001] This invention belongs to the field of biochemical catalysis technology, and particularly relates to a COF photocatalyst, its preparation method, and its application in photocatalytic regeneration of NADH. Background Technology

[0002] Catalytic synthesis of high-value-added organic compounds using naturally derived enzymes is a highly efficient synthetic method. This process generally requires the participation of coenzymes (reduced form, i.e., NADH or NADPH), while the oxidized form of the coenzyme (NADPH)... + or NADP + The cycle between the reduced form and the original form determines the efficiency of enzyme-catalyzed reactions to a certain extent. Therefore, it is necessary to design a highly efficient photocatalyst for the in-situ regeneration of reduced coenzymes (hereinafter referred to as coenzymes).

[0003] Covalent organic frameworks (COFs) are crystalline porous materials formed by covalent bonds. They have good conjugated ductility and strong structural tunability. After photocatalysis, their electronic states, pore size, and pore charge can be regulated, giving them broad application potential in coenzyme regeneration reactions. Summary of the Invention

[0004] Based on the above-mentioned technical problems, the present invention provides a COF photocatalyst, its preparation method and its application in photocatalytic regeneration of NADH. The COF photocatalyst is essentially a quaternized ammonium salt modified COF, which endows the COF with high positive charge density and specific configuration. Its preparation method is simple. When used for photocatalytic regeneration of NADH, it has the advantages of high enzyme regeneration efficiency, fast reaction, high selectivity and simple operation.

[0005] The present invention proposes a method for preparing a COF photocatalyst, comprising the following steps: S1. An aldehyde monomer and an amino monomer are subjected to a Schiff base condensation reaction, wherein at least one of the aldehyde monomer and the amino monomer contains a hydroxyl group, to obtain a covalent organic framework (COF) with a hydroxyl group. S2. The covalent organic framework (COF) and the bromoalkylammonium salt are subjected to a Williamson synthesis reaction to obtain the COF photocatalyst.

[0006] Preferably, the aldehyde monomer includes aldehydes containing hydroxyl groups and aldehydes without hydroxyl groups. The aldehyde containing hydroxyl groups is at least one of 2,5-dihydroxyterephthalaldehyde, 1,5-dihydroxynaphthalene-2,6-dicarboxaldehyde, or 1,8-dihydroxy-2,7-naphthalenedicarboxylaldehyde, preferably 2,5-dihydroxyterephthalaldehyde. The aldehyde without hydroxyl groups is at least one of terephthalaldehyde, 2,5-dimethoxyterephthalaldehyde, or 2,2'-bipyridine-5,5'-dicarboxaldehyde, preferably 2,2'-bipyridine-5,5'-dicarboxaldehyde. Preferably, the molar ratio of the aldehyde containing a hydroxyl group to the aldehyde without a hydroxyl group is 1:1-3.

[0007] Preferably, the amino monomer is at least one of 1,3,5-triaminobenzene, 1,3,5-tris(4-aminophenyl)benzene or 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, preferably 2,4,6-tris(4-aminophenyl)-1,3,5-triazine; Preferably, the molar ratio of the amino monomer to the aldehyde monomer is 1:1-2.

[0008] Preferably, in step S1, the Schiff base condensation reaction is carried out at a temperature of 100-150 °C for 60-84 h. Preferably, the Schiff base condensation reaction is carried out under an acidic reagent, and the reaction solvent is at least one of mesitylene, 1,4-dioxane, n-butanol, or o-dichlorobenzene.

[0009] Preferably, the brominated alkylammonium salt is at least one selected from (2-bromoethyl)trimethylammonium bromide, (3-bromopropyl)trimethylammonium bromide, or (4-bromobutyl)trimethylammonium bromide; Preferably, the mass ratio of the covalent organic framework (COF) to the brominated alkylammonium salt is 1:1-2.

[0010] Preferably, in step S2, the Williamson synthesis reaction is carried out at a temperature of 100-150 °C for 24-48 h. Preferably, the Williamson synthesis reaction is carried out under an alkaline reagent, which is at least one of K2CO3, Na2CO3, or NaOH.

[0011] This invention also proposes a COF photocatalyst, which is prepared by the above-mentioned preparation method.

[0012] The present invention also proposes an application of the above-mentioned COF photocatalyst in the photocatalytic regeneration of NADH.

[0013] Preferably, the application involves using oxidized coenzyme NAD.+ The reduced coenzyme NADH was obtained by reduction under the action of the COF photocatalyst.

[0014] Preferably, the application specifically includes: oxidized coenzyme NAD+ + The COF photocatalyst and the rhodium complex are mixed in a buffer solution and then reacted under light to obtain reduced coenzyme NADH.

[0015] In this invention, the application is essentially an oxidized nicotinamide adenine dinucleotide (oxidized coenzyme I, NAD). + The application of generating reduced nicotinamide adenine dinucleotide (reduced coenzyme I, NADH) belongs to the fields of COF synthesis, photocatalysis, and coenzyme regeneration.

[0016] In this invention, a COF is synthesized by a solvothermal method using at least one aldehyde monomer containing a hydroxyl group and an amino monomer. The COF structure contains a large number of hydroxyl groups. Using the Williamson reaction, these hydroxyl groups react with an alkyl bromide containing a quaternary ammonium salt, resulting in the removal of hydrogen bromide and the introduction of a quaternary ammonium salt onto the COF. The introduction of the quaternary ammonium salt allows the COF to react with NAD+. + Enhanced interactions between COF and NAD2 lead to electron and hole separation under visible light excitation. Electrons are then transferred to the substrate NAD2 via the intermediate rhodium complex. + The speed is faster, thus accelerating the overall reaction and achieving efficient catalytic conversion. Attached Figure Description

[0017] Figure 1 The X-ray powder diffraction pattern of the covalent organic framework (COF) described in Example 1 of this invention is shown below. Figure 2 Solid-state NMR of the covalent organic framework (COF) described in Example 1 of this invention 13 C spectrum; Figure 3 The X-ray powder diffraction pattern of the COF photocatalyst described in Example 1 of this invention is shown below. Figure 4 The image shows the UV-Vis absorption spectrum of the COF photocatalyst described in Example 1 of this invention. Figure 5 This is a transmission electron microscope image of the COF photocatalyst described in Example 1 of the present invention; Figure 6 This is a scanning electron microscope image of the COF photocatalyst described in Example 1 of the present invention; Figure 7 The graph shows the performance of the COF photocatalyst described in Example 1 of this invention for photocatalytic regeneration of NADH. Figure 8This is a cycle performance diagram of the COF photocatalyst described in Example 1 of the present invention for photocatalytic regeneration of NADH; Figure 9 This is a comparison chart showing the effect of the COF photocatalyst described in the embodiments and comparative examples of the present invention on the photocatalytic regeneration of NADH. Detailed Implementation

[0018] The present invention will now be described in detail through specific embodiments. However, these examples are clearly provided for illustrative purposes and are not intended to limit the scope of the invention.

[0019] Example 1 This embodiment proposes a method for preparing a COF photocatalyst, which is prepared by the following method: (1) Add 20 mg (0.056 mmol) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, 11.9 mg (0.056 mmol) of 2,2'-bipyridine-5,5'-dicarboxaldehyde and 4.7 mg (0.028 mmol) of 2,5-dihydroxy-terephthalaldehyde to a glass tube. Inject 0.9 mL of 1,3,5-trimethylbenzene and 0.1 mL of 1,4-dioxane into the glass tube using a syringe. After sonication for 10 min, the three solids are uniformly dispersed in the solvent. Then add 40 μL of glacial acetic acid. Subsequently, place the glass tube in a Dewar flask containing liquid nitrogen for freezing. Under vacuum, melt and seal the tube opening with a flame. Place the tube in an oven at 120 °C for 72 minutes. h, after being taken out and cooled to room temperature, the solid was taken out and washed several times with tetrahydrofuran until the supernatant was colorless, then washed twice with ethanol, centrifuged, and the supernatant was removed to obtain an orange-red solid. It was then dried in a vacuum drying oven at 60 °C to obtain a covalent organic framework (COF), denoted as TBD-COF. (2) Add 100 mg of TBD-COF, 100 mg of (2-bromoethyl)trimethylammonium bromide, and 100 mg of K2CO3 to a round-bottom flask, then add 20 mL of DMF. Purge with nitrogen for 15 min, then stir the reaction at 120 °C for 36 h. After the reaction is complete, cool to room temperature, centrifuge, remove the supernatant, wash the obtained solid twice with water and DMF, and finally wash three times with ethanol. Dry in a vacuum drying oven at 60 °C to obtain the COF photocatalyst, denoted as TBD-COF-N. + .

[0020] Example 2 This embodiment proposes a method for preparing a COF photocatalyst, which is prepared by the method described in Example 1, except that in step (2), (3-bromopropyl)trimethylammonium bromide is added instead of (2-bromoethyl)trimethylammonium bromide.

[0021] Comparative Example 1 This comparative example presents a method for preparing a COF photocatalyst, which is prepared by the method described in Example 1, except that step (2) is omitted and TBD-COF is used directly as the photocatalyst.

[0022] Comparative Example 2 This comparative example presents a method for preparing a COF photocatalyst, which is prepared by the method described in Example 1, except that sodium (2-bromoethyl)sulfonate is added in step (2) instead of (2-bromoethyl)trimethylammonium bromide.

[0023] Figure 1 The X-ray powder diffraction pattern of the covalent organic framework (COF) described in Example 1 of this invention is shown below. Figure 1 It can be seen that the main diffraction peak of the covalent organic framework (COF) is at 2θ = 2.53. o 4.20 o 5.14 o 6.47 o .

[0024] Figure 2 Solid-state NMR of the covalent organic framework (COF) described in Example 1 of this invention 13 C spectrum, refer to Figure 2 It can be seen that there are multiple sets of strong peaks in the 120-180 ppm range. This is the characteristic chemical shift region of aromatic ring carbons (such as benzene rings, triazine rings and other conjugated structural carbons) in COF, reflecting the presence of aromatic units in the COF skeleton.

[0025] Figure 3 The X-ray powder diffraction pattern of the COF photocatalyst described in Example 1 of this invention is shown below. Figure 3 It can be seen that the main diffraction peak of the COF photocatalyst is 2θ = 2.38. o .

[0026] Figure 4 The UV-Vis absorption spectrum of the COF photocatalyst described in Example 1 of this invention is shown below. Figure 4 It can be seen that COF photocatalysts have strong absorption in both the ultraviolet and visible regions.

[0027] Figure 5 The image shown is a transmission electron microscope (TEM) image of the COF photocatalyst described in Example 1 of this invention, with reference to... Figure 5 It can be seen that the COF photocatalyst exhibits a layered stacked morphology.

[0028] Figure 6 This is a scanning electron microscope image of the COF photocatalyst described in Example 1 of the present invention, with reference to... Figure 6It can be seen that the COF photocatalyst has an aggregated structure, a rough surface, obvious wrinkles, and a large specific surface area.

[0029] In this invention, to demonstrate the application of COF photocatalysts in the photocatalytic regeneration of NADH, the COF photocatalysts described in the examples and comparative examples are used as additives to regenerate oxidized coenzyme NAD. + To obtain reduced coenzyme NADH: Configure 10 mM NAD + Aqueous mother liquor, 10 mM rhodium complex The aqueous stock solution was used; during testing, the temperature was room temperature, and the reaction system was PBS 1X buffer at pH 7.2; specific applications included adding 200 μL of NAD+ to a transparent glass bottle. + The following were added: mother liquor, 6 mg of the COF photocatalyst described in the examples or comparative examples, 100 μL of an aqueous solution of the rhodium complex mother liquor, 150 μL of TEOA, and a certain amount of PBS to make the total solution volume 2 mL. A xenon lamp with a wavelength of 420 nm was used as the light source. After irradiation for a period of time, the reaction solution was diluted tenfold, filtered, and the absorbance of the system at 340 nm was measured using a UV-Vis spectrophotometer. The yield of NADH was calculated according to the formula, and the results are as follows: Figure 7 , 8 As shown in Figures 9 and 9.

[0030] Figure 7 The performance diagram of the COF photocatalyst described in Example 1 of this invention for photocatalytic regeneration of NADH is shown below. Figure 7 It can be seen that at the beginning of illumination, the reaction system did not have an obvious absorption peak at 340 nm (the characteristic absorption peak position of NADH). After 0.5 h of illumination, the absorption peak of the reaction system at 340 nm increased, indicating that NADH was generated. After 1 h of illumination, the absorbance at this point increased further.

[0031] Figure 8 The diagram shows the cycle performance of the COF photocatalyst described in Example 1 of this invention for photocatalytic regeneration of NADH. (Refer to...) Figure 8 It can be seen that the COF photocatalyst maintains high activity after three cycles, and the yield remains at around 90%.

[0032] Figure 9 This is a comparison chart showing the effects of the COF photocatalyst described in the embodiments and comparative examples of the present invention on the photocatalytic regeneration of NADH. (Refer to...) Figure 9 It can be seen that Example 1 has the best catalytic performance, with a yield of 92%, followed by Example 2 with a yield of 45%. Comparative Examples 1 and 2 have poor performance, with yields of 20% and 15%, respectively.

[0033] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a COF photocatalyst, characterized in that, Includes the following steps: S1. An aldehyde monomer and an amino monomer are subjected to a Schiff base condensation reaction, wherein at least one of the aldehyde monomer and the amino monomer contains a hydroxyl group, to obtain a covalent organic framework (COF) with a hydroxyl group. S2. The covalent organic framework (COF) and the bromoalkylammonium salt are subjected to a Williamson synthesis reaction to obtain the COF photocatalyst.

2. The method for preparing the COF photocatalyst according to claim 1, characterized in that, The aldehyde monomer includes aldehydes containing hydroxyl groups and aldehydes without hydroxyl groups. The aldehyde containing hydroxyl groups is at least one of 2,5-dihydroxyterephthalaldehyde, 1,5-dihydroxynaphthalene-2,6-dicarboxaldehyde, or 1,8-dihydroxy-2,7-naphthalenedicarboxylaldehyde, preferably 2,5-dihydroxyterephthalaldehyde. The aldehyde without hydroxyl groups is at least one of terephthalaldehyde, 2,5-dimethoxyterephthalaldehyde, or 2,2'-bipyridine-5,5'-dicarboxaldehyde, preferably 2,2'-bipyridine-5,5'-dicarboxaldehyde. Preferably, the molar ratio of the aldehyde containing a hydroxyl group to the aldehyde without a hydroxyl group is 1:1-3.

3. The method for preparing the COF photocatalyst according to claim 1 or 2, characterized in that, The amino monomer is at least one of 1,3,5-triaminobenzene, 1,3,5-tris(4-aminophenyl)benzene or 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, preferably 2,4,6-tris(4-aminophenyl)-1,3,5-triazine; Preferably, the molar ratio of the amino monomer to the aldehyde monomer is 1:1-2.

4. The method for preparing the COF photocatalyst according to any one of claims 1-3, characterized in that, In step S1, the Schiff base condensation reaction is carried out at a temperature of 100-150 °C for 60-84 h. Preferably, the Schiff base condensation reaction is carried out under an acidic reagent, and the reaction solvent is at least one of mesitylene, 1,4-dioxane, n-butanol, or o-dichlorobenzene.

5. The method for preparing the COF photocatalyst according to any one of claims 1-4, characterized in that, The bromoalkylammonium salt is at least one of (2-bromoethyl)trimethylammonium bromide, (3-bromopropyl)trimethylammonium bromide, or (4-bromobutyl)trimethylammonium bromide; Preferably, the mass ratio of the covalent organic framework (COF) to the brominated alkylammonium salt is 1:1-2.

6. The method for preparing the COF photocatalyst according to any one of claims 1-5, characterized in that, In step S2, the Williamson synthesis reaction is carried out at a temperature of 100-150 °C for 24-48 h. Preferably, the Williamson synthesis reaction is carried out under an alkaline reagent, which is at least one of K2CO3, Na2CO3, or NaOH.

7. A COF photocatalyst, characterized in that, It is prepared by the preparation method described in any one of claims 1-6.

8. The application of the COF photocatalyst according to claim 7 in the photocatalytic regeneration of NADH.

9. The application of the COF photocatalyst according to claim 8 in the photocatalytic regeneration of NADH, characterized in that, The application involves using oxidized coenzyme NAD. + The reduced coenzyme NADH was obtained by reduction under the action of the COF photocatalyst.

10. The application of the COF photocatalyst according to claim 9 in the photocatalytic regeneration of NADH, characterized in that, The specific application includes: using oxidized coenzyme NAD. + The COF photocatalyst and the rhodium complex are mixed in a buffer solution and then reacted under light to obtain reduced coenzyme NADH.

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