Preparation method and application of donor-receptor type two-dimensional imino CTF photocatalyst

Abstract

The invention provides a preparation method and application of a donor-receptor type two-dimensional imino CTF photocatalyst, and belongs to the technical field of photocatalyst preparation.The preparation method of the CTF photocatalyst comprises the following steps that 2, 4, 6-tris (4-aminophenyl)-1, 3, 5-triazine, terephthalaldehyde and 2, 4, 6-tris (4-aminophenyl)-1, 3, 5-triazine are mixed according to a certain proportion, and the donor-receptor type two-dimensional imino CTF photocatalyst is obtained. The preparation method comprises the following steps: by taking 2, 5-dimethoxy terephthalaldehyde or 2, 5-dihydroxy terephthalaldehyde as a raw material, reacting in a mixed solution of mesitylene / dioxane / acetic acid in a certain proportion for 3 days by adopting an inert gas sealing-solvothermal method, centrifuging the obtained product, sequentially washing with tetrahydrofuran and acetone for multiple times, and carrying out vacuum drying, thereby obtaining the 2, 5-dimethoxy terephthalaldehyde / 2, 5-dihydroxy terephthalaldehyde. The two-dimensional triazine CTF photocatalysts with different donor-receptor types are obtained. The preparation method comprises the following steps: by taking acetonitrile as a solvent, dispersing a photocatalyst into an arylamine solution with a certain concentration, stirring for 0.5 hour in a dark place, and carrying out catalytic reaction under visible light (lambda is greater than or equal to 420 nm), so that the preparation of the high-efficiency catalytic arylamine oxidative coupling reaction under the visible light is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of photocatalyst preparation, and specifically relates to a preparation method of a donor-acceptor type two-dimensional imine-based CTF photocatalyst and its application in a photocatalytic aromatic amine oxidative coupling reaction. Background of the Invention

[0003] Imines and their derivatives are important intermediates of nitrogen-containing heterocyclic compounds in the fine chemicals and pharmaceutical industries. It is well known that the C=N double bond in imines has high reactivity and can undergo a series of reactions such as reduction, addition, condensation and cyclization. It is an important active structural unit for many bactericides, anti-tumor and antiviral drugs. However, the traditional preparation process faces problems such as large environmental pollution and limited catalytic activity. Therefore, the use of photocatalytic technology to convert solar energy into chemical energy and realize the conversion of organic reactions provides a good solution to the traditional energy crisis and environmental pollution problems faced today. How to design an efficient and stable photocatalytic system and efficiently photocatalyze the oxidative coupling reaction of aromatic amines is crucial to promoting the technological development of such reactions.

[0004] At present, a variety of amorphous porous organic materials such as HCPs and CMPs have been reported and used to study the catalytic performance of such self-coupling reactions. For example, the Su group obtained carbazole-based conjugated microporous polymers through the oxidative coupling polymerization of carbazole; the polymer has porosity, high specific surface area, molecular tunability and high stability, and can be used as an efficient heterogeneous photocatalyst for photocatalytic oxidative coupling of primary amines and selective oxidation of sulfides and other aerobic reactions. This work highlights the great advantages of developing efficient, metal-free photocatalysts. Zhi Yongfeng's group at Jilin University synthesized a porous organic hypercrosslinked polymer based on carbazole-fluorenone in one step through the Friedel-Craft alkylation method. This polymer can be used as a low-cost, metal-free heterogeneous photocatalyst and used to efficiently catalyze the oxidative coupling reaction of primary amines and other aerobic reactions. These research works not only provide new ideas for the synthetic application of green chemistry, but also open up new ways to design and construct excellent heterogeneous photocatalysts at the molecular level.

[0005] Covalent organic framework (COFs) materials are a new generation of crystalline porous polymer materials with a periodic structure of permanent porosity. Unlike amorphous porous organic materials generated under kinetically controlled irreversible reactions, COFs materials are generated by thermodynamically controlled reversible reactions and have a regular crystal structure. In addition, the large π-conjugated system in the framework structure has potential multifunctional photophysical and electronic properties, which provides advantages for light harvesting and photocatalytic applications. In addition, the large specific surface area and adjustable porosity of COFs materials provide space for substrate transport and conversion; its ability to accept and transmit light energy in the non-localized main chain helps to promote light harvesting and energy transfer to adsorbed substrate molecules, thereby causing physical and chemical changes toward the product. In addition, the regular crystal structure can produce electronic coupling and improve the transmission capacity of photogenerated electrons. By designing different microstructural units of COF materials, such as adjusting their degree of conjugation and the density of active sites, the absorbance, band gap and band structure properties can be adjusted to optimize energy transfer and photocatalytic performance. More importantly, the skeleton structure of the two-dimensional COFs material is limited to the plane, so it can present a layered stacking structure and form a periodic columnar π-array. The ordered columnar π-array is an ideal channel for exciton diffusion, charge migration and separation, which makes the two-dimensional COFs material show excellent effects in the optoelectronic field. Therefore, it is of great significance to design and prepare two-dimensional triazine COF (CTF) materials with different donor-acceptor types by adjusting the microstructure unit, and study their catalytic performance in the photocatalytic oxidative coupling reaction of aromatic amines. Summary of the invention

[0006] The purpose of the present invention is to provide a donor-acceptor type two-dimensional CTF photocatalyst and a preparation method thereof, and to study the catalytic application of the photocatalyst to the oxidative coupling reaction of aromatic amines. The photocatalyst prepared by the present invention has a large specific surface area, high photocatalytic efficiency, and broad application prospects.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing a donor-acceptor type two-dimensional imine-based CTF photocatalyst comprises the following steps:

[0009] 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, aromatic aldehyde compounds, mixed solvents and a certain concentration of acetic acid aqueous solution are mixed, sealed with an inert gas, heated to not less than 100°C and reacted. After reacting for not less than 48 hours, the mixture is centrifuged, washed and dried to obtain a donor-acceptor type two-dimensional imine-based CTF photocatalyst.

[0010] The aromatic aldehyde compound is one or two of terephthalaldehyde, 2,5-dimethoxyterephthalaldehyde or 2,5-dihydroxyterephthalaldehyde.

[0011] The mixed solvent is a mixed solution of mesitylene and dioxane;

[0012] The molar ratio of the mixed solvent is 1:1;

[0013] Preferably, in the step, the molar ratio of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine to the aromatic aldehyde compound is 1:3-1:1, the molar ratio of terephthalaldehyde to 2,5-dimethoxyterephthalaldehyde, terephthalaldehyde to 2,5-dihydroxyterephthalaldehyde or 2,5-dimethoxyterephthalaldehyde to 2,5-dihydroxyterephthalaldehyde in the aromatic aldehyde compound is 1:4-3:4, the molar ratio of the mixed solvent to the acetic acid aqueous solution is 10:1-2:1, and the concentration of the acetic acid aqueous solution is 1 mol / L-10 mol / L.

[0014] Preferably, the reaction temperature in the step is 100° C.-140° C., the reaction time is 48 h-72 h, and after the reaction is completed, the mixture is centrifuged, washed three times with tetrahydrofuran and acetone in sequence, and dried at 60° C. overnight.

[0015] The application of the donor-acceptor type two-dimensional imine-based CTF photocatalyst in the photocatalytic oxidative coupling reaction of aromatic amines is as follows:

[0016] The photocatalyst was dispersed in a certain concentration of aromatic amine solution using acetonitrile as solvent, stirred for 0.5 h in the dark, and then the catalytic reaction was carried out under visible light (λ≥420 nm).

[0017] Preferably, the aromatic amine compound in the method is one of benzylamine, p-methylbenzylamine, p-methoxybenzylamine, p-chlorobenzylamine and p-nitrobenzylamine.

[0018] Preferably, in the method, the mass ratio of the photocatalyst to the aromatic amine compound is 1:20-1:2.

[0019] Preferably, the molar number of aromatic amine in the method is 0.2 mmol, the volume of acetonitrile is 2 mL, and the reaction time is 5 h-10 h.

[0020] The present invention designs and prepares a two-dimensional CTF photocatalyst containing different supply-receiver microscopic units, which effectively improves the migration rate of photogenerated carriers of the photocatalyst, regulates the appropriate valence band position of the photocatalyst, and improves the catalytic performance of the photocatalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 1 is the XRD pattern of X%CTF prepared by solvothermal method in Example 4, Example 6 and Example 7.

[0022] Figure 2 This is the infrared spectrum of 100% CH3O-CTF and CTF photocatalyst in Example 4.

[0023] Figure 3 Infrared spectra of 100% HO-CTF synthesized by different synthesis methods. Specific implementation method:

[0024] The present invention is further described below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0025] Embodiment 1:

[0026] A preparation method of 25% CH3O-CTF photocatalyst comprises the following steps: placing a certain proportion of terephthalaldehyde, 2,5-dimethoxyterephthalaldehyde and 1,3,5-tris(4-aminophenyl)triazine (molar ratio of 9:3:8) in a Schlenk tube in sequence, adding 2 mL of a mixed solvent (dioxane / mesitylene, 0.4 mL / 1.6 mL), adding 0.2 mL of an acetic acid aqueous solution (6 M) after ultrasonication, degassing three times and then heating at 120° C. for 3 days, cooling, centrifuging, washing with tetrahydrofuran and acetone in sequence, and drying at 60° C. overnight.

[0027] Embodiment 2:

[0028] The preparation method in this embodiment refers to Example 1, the only difference is that the molar ratio of terephthalaldehyde, 2,5-dimethoxyterephthalaldehyde and 1,3,5-tris(4-aminophenyl)triazine in this embodiment is 3:3:4, and the other conditions remain unchanged to obtain 50% CH3O-CTF photocatalyst.

[0029] Embodiment 3:

[0030] The preparation method in this embodiment refers to Example 1, the only difference is that the molar ratio of terephthalaldehyde, 2,5-dimethoxyterephthalaldehyde and 1,3,5-tris(4-aminophenyl)triazine in this embodiment is 3:9:8, and the other conditions remain unchanged to obtain 75% CH3O-CTF photocatalyst.

[0031] Embodiment 4:

[0032] The preparation method in this embodiment refers to that in Embodiment 1, except that the molar ratio of 2,5-dimethoxyterephthalaldehyde to 1,3,5-tris(4-aminophenyl)triazine in this embodiment is 3:2, and the other conditions remain unchanged to obtain 100% CH3O-CTF photocatalyst.

[0033] Embodiment 5:

[0034] A preparation method of 25% OH-CTF photocatalyst comprises the following steps: placing a certain proportion of terephthalaldehyde, 2,5-dihydroxyterephthalaldehyde and 1,3,5-tris(4-aminophenyl)triazine (molar ratio of 9:3:8) in a Schlenk tube in sequence, adding 2 mL of a mixed solvent (dioxane / mesitylene, 0.4 mL / 1.6 mL), adding 0.2 mL of an acetic acid aqueous solution (6 M) after ultrasonication, degassing three times and then heating at 120° C. for 3 days, cooling, centrifuging, washing with tetrahydrofuran and acetone in sequence, and drying at 60° C. overnight.

[0035] Embodiment 6:

[0036] The preparation method in this embodiment refers to Example 5, the only difference is that the molar ratio of terephthalaldehyde, 2,5-dihydroxyterephthalaldehyde and 1,3,5-tris(4-aminophenyl)triazine in this embodiment is 3:3:4, and the other conditions remain unchanged to obtain 50% OH-CTF photocatalyst.

[0037] Embodiment 7:

[0038] The preparation method in this embodiment refers to Example 5, the only difference is that the molar ratio of terephthalaldehyde, 2,5-dihydroxyterephthalaldehyde and 1,3,5-tris(4-aminophenyl)triazine in this embodiment is 3:9:8, and the other conditions remain unchanged to obtain 75% OH-CTF photocatalyst.

[0039] Embodiment 8:

[0040] The preparation method in this embodiment refers to that in Embodiment 5, except that the molar ratio of 2,5-dihydroxyterephthalaldehyde to 1,3,5-tris(4-aminophenyl)triazine in this embodiment is 3:2, and the other conditions remain unchanged to obtain 100% OH-CTF photocatalyst.

[0041] Embodiment 9:

[0042] CTF photocatalyst catalyzes the oxidative coupling reaction of benzylamine. The specific experimental process is as follows: 20 mg of the 100% CH3O-CTF photocatalyst prepared in Example 4 is dispersed in 0.2 mmol of acetonitrile solution (2 mL) of aromatic amine, stirred for 0.5 h in the dark, and then reacted under 300 W xenon lamp (with filter, λ≥420 nm) for 5 h. After filtering out the catalyst, the filtrate is analyzed by gas chromatography for yield, which is 19%.

[0043] Embodiment 10:

[0044] The photocatalytic performance measurement in this example refers to Example 9, the only difference being that the photocatalyst used in this example is the 100% OH-CTF photocatalyst prepared in Example 8, with a yield of 51%.

[0045] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A donor-acceptor type two-dimensional imine-based CTF photocatalyst, characterized in that: The preparation method comprises the following steps: 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, aromatic aldehyde compounds, mixed solvents, and acetic acid aqueous solution of a certain concentration are mixed, sealed with an inert gas, heated to not less than 100°C, reacted, centrifuged, washed, and dried after reacting for not less than 48 hours, to obtain a donor-acceptor type two-dimensional imine-based CTF photocatalyst; The aromatic aldehyde compound is one or two of terephthalaldehyde, 2,5-dimethoxyterephthalaldehyde or 2,5-dihydroxyterephthalaldehyde; The mixed solvent is mesitylene and dioxane; The molar ratio of the mixed solvent is 1:

1.

2. The method for preparing the CTF photocatalyst according to claim 1, characterized in that: The molar ratio of the 2,4,6-tris(4-aminophenyl)-1,3,5-triazine to the aromatic aldehyde compound is 1:3-1:

1.

3. The method for preparing the CTF photocatalyst according to claim 1, characterized in that: The molar ratio of terephthalaldehyde to 2,5-dimethoxyterephthalaldehyde, terephthalaldehyde to 2,5-dihydroxyterephthalaldehyde or 2,5-dimethoxyterephthalaldehyde to 2,5-dihydroxyterephthalaldehyde is 1:4-3:

4.

4. The method for preparing the CTF photocatalyst according to claim 1, characterized in that: The molar ratio of the mixed solvent to the acetic acid aqueous solution is 10:1-2:

1.

5. The method for preparing the CTF photocatalyst according to claim 1, characterized in that: The concentration of the acetic acid aqueous solution is 1 mol / L-10 mol / L.

6. The method for preparing a CTF photocatalyst according to any one of claims 2 to 5, characterized in that: The reaction temperature is 100-140°C; the reaction time is 48h-72h; after the reaction is completed, centrifuge, wash with tetrahydrofuran and acetone in turn, wash with each solvent 3 times; dry at 60°C overnight.

7. Use of the donor-acceptor type two-dimensional imine-based CTF photocatalyst according to claim 1 in the preparation of photocatalytic oxidative coupling reaction of aromatic amines.

8. The use according to claim 7, characterized in that: The method is as follows: using acetonitrile as solvent, dispersing the photocatalyst in a certain concentration of aromatic amine solution, stirring for 0.5 h in a dark environment, and then carrying out a catalytic reaction under visible light (λ≥420 nm).

9. The use according to claim 8, characterized in that: The aromatic amine is one of benzylamine, p-methylbenzylamine, p-methoxybenzylamine, p-chlorobenzylamine and p-nitrobenzylamine.

10. The use according to claim 8, characterized in that: The mass ratio of the photocatalyst to the aromatic amine is 1:20-1:

2.

11. The use according to claim 8, characterized in that: The molar number of aromatic amine is 0.2 mmol, the volume of acetonitrile is 2 mL, and the reaction time is 5 h-10 h.

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